Saturday, December 26, 2015

Parthenogenesis a.k.a. Virgin Birth

Note: This show first aired on December 26, 2015.

Late December is the dark time here in the northern hemisphere, and many world religious and spiritual traditions mark the celestial event, the winter solstice with introspection and a celebration of the return of the light. From here the days only get longer again, until June at least.

A central narrative to one of these coopted solistice worshiping holidays though, has nothing to do with darkness and light, and everything to do with an event that theoretically occurred 9 months before what has become a major American commercial holiday. I’m talking of course about virgin conception and birth, a major article of faith in the Christian tradition. But virgin birth also has biological precedents, though not in humans or any other mammals for that matter.

First lets quickly review what we consider “normal” sexual reproduction. Genetic material from one parent and genetic material from a second parent combines to make an individual with a uniquely mixed set of genes. Each parent gives half of the genes, via the gametes, the sperm and the eggs. Sperm and eggs each carry only half of the genetic material required to make up a new individual. In genetic terminology this is called being haploid, sperm and eggs are both haploid cells, they only have one set of genetic material, all of the other cells in the body have two sets of genetic material, called diploid. Yes there are many species that have MORE than two sets of genetic material in their cells, this is called polyploidy and it is very common in plants, and is most well represented in the animal kingdom by fish. We’re going to focus on typical diploid animals for the purposes of this explanation, though.

In virgin birth, more accurately called parthenogenesis, a new individual is created without the benefit of having genetic material from two different parents. There are two basic ways this can happen. One is that the genetic material in the haploid egg replicates itself changing the egg from haploid to diploid, or with two sets of genetic material. That cell then develops like any fertilized embryo, except that it only has genetic material from the mother, and only one set of genetic material from the mother at that, so it is an exact and complete clone of the mother. The other way is that there is some genetic recombination that occurs either as a result of fusion occurring during meiosis (or gamete production) or via the egg being fertilized by what is called a polar body (which is a cell left over from when the egg was produced). These second methods all lead to an individual that is not a full clone of the mother, but what is called a half clone. Half of the genetic material is exactly the mother’s, while the other half has undergone some degree of recombination depending on the exact mechanics of this type of parthenogenesis, there are actually several routes to this end.

Parthenogenesis does occur in nature, in the animal kingdom alone it is common in invertebrates, and of the vertebrates, amphibians, reptiles, birds and especially fish exhibit this behavior. There are at least 80 species of non mammalian vertebrates that are fully unisexual, meaning there are no males, and reproduction is obligate parthenogenesis. Many more vertebrates demonstrate facultative parthenogenesis, meaning they can reproduce this way, but more typically (we think) reproduce sexually.

So the Christmas story has some biological basis, though parthenogenesis is not documented in mammals, and because mammals have an XX XY sex determination system, and sex is determined by genes carried on the sperm, if mammals could do parthenogenesis, all of the offspring would be female, which certainly adds a twist to the classic Christmas story.

Happy Holidays everyone.


About Komodo dragons (who have exhibited parthenogenesis)

Vrijenhoek, R.C., R.M. Dawley, C.J. Cole, and J.P. Bogart. 1989. A list of the known unisexual vertebrates, pp. 19-23 in: Evolution and Ecology of Unisexual Vertebrates. R.M. Dawley and J.P. Bogart (eds.) Bulletin 466, New York State Museum, Albany, New York

Saturday, December 19, 2015

El Nino

Note this program first aired December 19, 2015.

The last two winters here in Maine have been long, cold and snowy thanks to persistent upper atmosphere air masses and the loopiness of the polar vortex. Many people I know are gearing up for more of the same this winter, but I am not ready to make any bets yet, and that is because of one big difference between last winter and this winter, El Nino.

Surely you have heard by now that this winter, the winter of 2015/16 is shaping up to be one of the strongest El Nino events in recent history, vying for the top spot with the winter of 1982/83 and 1997/98. El Nino is the common name for a oceanographic and atmospheric phenomenon or set of phenomena that occur in the Pacific Ocean but influence weather world wide. Meteorologists and climate scientists refer to the whole package as ENSO, short for El Nino Southern Oscillation, a name that gets us a little closer to what is actually happening in the Pacific Ocean this winter.

We take for granted that the ocean plays a huge role in our weather patterns and long term climate, we take it so much for granted that we never think about it, until something like a strong El Nino comes along. In the equatorial Pacific the typical ocean pattern runs east/west. Warm surface water is found in the western Pacific, held there by the prevailing winds, the trade winds which blow east to west. That net movement of surface water from east to west drives upwelling in the eastern Pacific, which means cool deep water comes to the surface. So, warm in the western ocean off Papua New Guinea, cool in the eastern ocean off South America. That warm water warms the atmosphere above it, creating low pressure and bringing lots of precipitation to the western Pacific region. The cold water in the eastern Pacific keeps the air mass there cool, maintaining high pressure and relatively dry conditions.

When an El Nino happens, this pattern totally reverses. It isn’t clear exactly whether the chicken or the egg comes first but several things happen that culminate in what we call El Nino. The trade winds diminish, so the wind doesn’t blow as strongly from east to west, and in some cases actually reverses and blows from west to east.  Without the wind holding it there, the warm surface water in the western Pacific moves back across the ocean towards the eastern Pacific. Because the wind drives that upwelling of cold water off Peru I mentioned, no wind means no upwelling. With warm water heading east, and no cold water to cool the eastern ocean, the Pacific ocean off south America gets warm, and that is the hallmark sign of El Nino. That warm water has profound effects locally, dramatically diminishing the productivity of the waters off Ecuador and Peru. Oceanic food chains start with phytoplankton, and with no nutrient rich deep water coming to the surface, the phytoplankton don’t survive. And if there are no phytoplankton that ripples all the way up the food chain.

As far as we are concerned, it isn’t the warm water in the eastern Pacific that changes our winters, but the warm air mass above that warm water. Warm moist air leads to low pressure, in an area where there is usually high pressure. This switch in pressure regime can drive changes in the way air masses travel across north America in the winter, strengthening the east/west flow of the jet stream, reducing the chance of the north/south loopiness of the polar vortex we’ve experienced the last couple of winters. Typical effects are increased precipitation in the southeast and west, and warmer winters across the northern tier of the US and southern Canada.

So is El Nino responsible for this extraordinarily warm December we’re having? Its hard to tell. It is staying warm because the air masses that are dominating the continental US are coming from the Pacific Ocean, rather than the Canadian Arctic, that warm Pacific air is blocking the jet stream from coming south, and it may be related to El Nino. We should remember however, that last December was pretty warm too, without an El Nino, it was 54 degrees on Christmas Day at my house last year. El Nino doesn’t mean that it will be an effortless balmy winter. If you think back to January of 1998, you might remember a little event we like to call the Ice Storm. So we will have to wait and see how this all plays out. I’m beginning to think though, it might have been the wrong winter to buy new skis. I hope I’m wrong.


NASA/Goddard Space Flight Center. "NASA studying 2015 El Nino event as never before." ScienceDaily. ScienceDaily, 19 October 2015.

Accuweather’s White Christmas prediction map
The straight talk from NOAA

Even straighter talk from the Weather Channel

There’s even an El Nino blog (it is really good, check it out)

Saturday, October 17, 2015

El Faro

Note: This program first aired October 17, 2015.

I work here in Maine, at a maritime college, a school who’s mission is to train young women and men to drive and power the thousands of ships sailing at any given moment on the ocean. Ships that transport consumer goods and bulk commodities, food and cars, oil, gas and coal, ships that carry humans from place to place, ships that ply every available waterway on the planet. It’s been a hard couple of weeks on campus, if you have been following the news, you will understand why. A ship carrying five alumni, including some very recent graduates, drove straight into the path of a major hurricane and sank. The entire crew of 33 was lost at sea.

Humans have had a relationship with the sea from the beginning of our existence. There is evidence that as we evolved in the open woodlands and grass lands of Africa, climatic shifts pushed us to spread out, and as we spread, we made it to the coast line and found the ocean. One hypothesis has it that it was the nutritional content of sea food that enabled our brains to evolve to what they are today. Evolution aside we are sea loving people. In the US over 39% of the population lives in coastal shoreline counties, over 123 million people. The numbers are similar if not higher world wide.

We have used the sea as a source of food, a medium for migration and trade, and even a spiritual well spring. Those most comfortable at sea are truly a breed apart, I see this in my students all the time. They can’t really explain it but they are happiest with the open horizon in front of them, nothing but water around them, the deck in motion under their feet. I once went to the Aran Islands on the west coast of Ireland, and it was the first place I had been where I felt in a visceral way that there was enough room for my head, enough space for my mind to wander. I suspect that is what mariners feel on the sea, that and freedom. On the sea the rules of land don’t apply, until of course, they do. The sea may make you feel free and invincible, but this, like nearly every human story, is an illusion.

I am reading Moby Dick with my students this semester, and Melville captures this essence perfectly, in the chapter called Brit he writes “…by vast odds, the most terrific of all mortal disasters have immemorially and indiscriminately befallen tens and hundreds of thousands of those who have gone upon the waters, though but a moment’s consideration will teach, that however baby man may brag of his science and skill, and however much, in a flattering future, that science and skill may augment; yet for ever and for ever, to the crack of doom, the sea will insult and murder him, and pulverize the stateliest, stiffest frigate he can make; never the less, by the continual repetition of these very impressions, man has lost that sense of the full awfulness of the sea which aboriginally belongs to it.” And a few lines later it continues “Yea, foolish mortals, Noah’s flood is not yet subsided; two thirds of the fair world it yet covers.”

We developed bipedal motion to carry these big brains around, and these big brains have gotten us out of some pretty amazing situations (Apollo 13 anyone?). But its in our hearts where humility dwells, and I think we love the ocean for that reason, she is a wilderness and we set sail on her at our peril. Science and skill could not save the well trained mariners of the El Faro. Science and skill could not help the Coast Guard rescuers find the ship or crew, flying at the outer limits of possibility in nearly impossible conditions. We’ve got the equation all wrong, it isn’t our intelligence and ingenuity that is limitless, its the power of the sea.


On humans and seafood:

UN on coastal population

Saturday, October 3, 2015

Food Transformation or the Magic that is Bacon

Note: This program first aired October 3, 2015.

My friend Wendy and I were talking about food recently, and the topic of bacon came up. In some circles, bacon makes everything better. As we talked I described what amazing animals pigs are, and how they take stuff we can’t eat and turn it into bacon. And that is the essence of the magical transformation that is a food system. Everything has to eat something whether that something is plant or animal or fungus or bacteria. As humans we are omnivores, and have a wide range of foods available to us, and by available I mean food we can access, digest and find palatable. But there are lots of things on this planet we don’t eat or more significantly, can’t eat and that is true for all organisms. The wonderful thing about an interdependent food system is that other organisms can make use of things that you can’t, and if you able to eat the organism in question, you can effectively widen the radius of your available food sphere.

This is a common practice in agriculture. Many small progressive farms practice rotational grazing, where large animals are grazed on a plot of land for a period of time and then moved to a different pasture. They leave behind manure that enriches the soil, but more than that attracts flies which lay their eggs in the manure. Chickens are then rotated into the pasture. Chickens take things most of us don’t want to eat, like maggots, and turn them into things most of us do want to eat, like eggs. Now to be fair, we could eat maggots, and in some cultures, beetle larva are a prized food source. But if I have to eat maggots, I would rather have them processed through a chicken first. For a less gross example, cows take things we can’t eat, like grass, we can’t get any nutrition out of grass, it is indigestible for us, and cows turn it into things many of us can and do eat, like beef and milk. Even pigs, they take food no longer fit for human consumption, and turn it into bacon. If you hunt, wild animals do the same thing, transforming tree bark and leaf bud, hemlock needles and twigs into nutritious edible matter.

It isn’t just animals that perform this magic. You can be a vegan and still find wonder in this process. Mushrooms are heterotrophs like us, in that they don’t make their own food, they find it in the external environment. Mushrooms take stuff that is entirely inedible to us, wood, and turn it into something we can eat. Plants are the ultimate practitioners of this ancient art, they take air and make food. Yes, plants make food out of air. The energy stored in the food comes from the sun, but the material portion of that food comes literally from thin air.

If you think about it, this should feel like magic, and you should feel incredibly lucky that all of these organisms perform this magical transformation. In reality though, it isn’t magic, it is simply biology following the rules of physics. Matter is neither created nor destroyed, it just keeps getting rearranged. Life is the ultimate upcycler.

You’ve heard of recycling, taking trash and using it as raw material for something new. There is no trash in nature. But biology doesn’t just take old plastic bottles and make plastic lawn furniture and decking out of it. Biology is actually an up-cycler. Biology takes maggots and grubs and makes eggs and chicken, takes grass and hay and makes ice cream, takes rotting wood and makes chanterelles, takes air and water and makes broccoli, takes food waste and makes bacon.

Be a link in your own food chain. See yourself as the link in the food chain that you are, and realize there are no six degrees of separation when it comes to food. Your blueberry muffin, bacon breakfast sandwich, bowl of yogurt and granola or tofu veggie scramble are but one degree separated from things inedible. And in that one degree is what separates that which is living from that which is not.

Saturday, September 26, 2015

I'm a Heterotroph

Note: This program first aired September 26, 2015

I am a heterotroph. This means that I eat food, food that comes from outside of my body. Unlike plants, which are able to make their own food within specialized cells within their bodies. I can’t do that. To live I have to eat, and what I eat is important to me.

One of the things I eat is meat, though not very much of it, and mostly meat I have looked in the eyes. In the yard behind my green house are two tidy wooden houses. One is fully of baby chickens, the other full of baby ducks. A few of these birds will join my flock of laying hens, or go to live as slug eating garden ducks for my neighbor, the majority will end up in my freezer, sustaining me and my husband over the winter. I’ve participated in this process for several years, raising or helping to raise the meat that fills my freezer, and when the day comes deconstructing the animals from which I derive my nourishment. I do this not without pause, in many ways I would prefer not to eat animals at all. Watching the ducks embody their inherent duckness, splashing in their water with apparent pleasure, watching the chickens doing what is theirs’ to do, scratching in the soil looking for invertebrates, its hard not to appreciate watching an animal do what it is designed to do.

By all measures I am a greenhorn when it comes to my small homestead. And this fall has highlighted this fact. This fall the “raise your own meat” story didn’t exactly follow the script. It started with a text from my husband that simply read “we may lose a duck”. He went out to do the morning chores and found one of the ducks on its back, waving its legs, unable to stand. He flipped it over but it was unable to stand, and it flopped back over on to its side. We isolated it from the flock by bringing it inside in its own quarantine box in the bathroom. It wouldn’t eat, could not sit upright or bend its legs and would drink only if you put its beak in the water. Its condition worsened and the duck was dead by nightfall. Two days later the process repeated, only this time the duck survived the night, flopping around in its box all night, only to die in the morning.

It wasn’t easy to watch those animals die. They suffered, and the only thing that would perhaps have made them feel better would have been to be reunited with their flock, something we couldn’t do because we suspected that what was killing them was contagious. Using the hard economics of a small homestead, we had to decide how much money to spend to save a duck that we were going to kill in 8 weeks anyway. But even though their fate is the freezer, I care about those animals, I enjoy watching them embody their duckness, and it is critically important to me that they are able to do the things most important to them-wander about in the fresh air, splash in the water, snuggle with their flock mates. Watching an animal suffer when you don’t know what is wrong and are powerless to provide comfort is a reality check indeed. Ultimately we brought the second duck to the University of Maine for a necropsy and bacterial culture to try to get some answers, and while we were waiting for the results a third duck fell ill.

This story though has a happy ending. The third duck spent the night in the house with us, and was able to eat and drink the whole time. He maintained the ability to walk, and was well enough that in the morning I put him outside in a small quarantine pen. He had recovered enough that evening that I reunited him with his flock, and when they came out of the duck house the next morning, I couldn’t tell which one had been sick the day before. Cue the happy music.

Being an active participant in your own food chain isn’t always easy but it will challenge you in all the best ways, and provide endless opportunities to examine your own values and priorities. It may change the way you eat. I’ll always be a heterotroph, but I’m not sure I’ll always be a meat eater. The ducks may have more to teach me still.

Saturday, August 29, 2015

Blackberries and Summer

Note: This program first aired August 29, 2015.

Late summer is one of my favorite times of year. The expansive energy of summer starts to wane as plants start their journey to winter dormancy. Birds cram in the as many fat and juicy insects as they can, and start making their way to warmer climes. For many of us humans the school year is starting back up and though we mourn the end of summer the structure of fall is just what we need. And most importantly, late summer is when my favorite wild fruit ripens and is there for the taking, road side and trailside.

Blackberries are a common late summer fruit here in Maine, coming after the strawberries of early summer, the blue berries and raspberries of mid to late-ish summer. Blackberries mean the end really is nigh. Some summers in recent memory, the chill of fall started before the blackberries were able to fully ripen, and we never got our end of summer treat.

When we say “blackberries” we are really talking about several species of plants in the genus Rubus. Rubus is a real head ache for botanists, as the species are difficult to tell apart and hybridize (or cross breed) in the wild readily. This cross breeding ability has made it easy to develop all kinds of interesting agricultural cultivars, but it makes sorting out the taxonomy of wild plants very difficult. Estimates for the number of Rubus species world wide range from 250 to 700 because different botanists treat the genus with differing degrees of discernment. On the one hand we have the “megaspecies” approach, lumping many disparate species together based on one common characteristic. On the other hand, similar plants can be separated into different species based on minute or inconsistent characteristics. Hence the range, the taxonomy of Rubus is still an open debate.

Regardless of exactly how many species are in the genus, Rubus includes along with blackberries and raspberries, plants with dreamy sounding names like dew berry, cloud berry and baked apple berry. All of these berries are technically aggregates of a type of fruit called a drupe. Drupes are stone fruits, consisting of a fleshy pulpy layer surrounding an inner hard seed, think a peach, plum or avacado. Blackberries and their kin are made up of lots of little drupes, called drupelets, clustered together in one delicious berry. These berries mostly share another characteristic in their growth form. They are perennial, growing from multiyear root system, but the above ground portion of the plant is a woody cane that lives as a biennial, or for two years. The first year the cane grows it is called the primocane. It has lots of leaves but no flowers or fruit. Think about all the lush green leafy blackberry brambles you have seen and wondered why there were no berries. They were primocanes, that’s why. The primocanes overwinter and produce lateral branches that flower and fruit the second year. These flowering canes are referred to as floricanes. And if you want to take on the challenge of identifying Rubus to species, knowing the difference between floricanes and primocanes is essential. In any given patch of blackberries, there should be both primocanes and floricanes, so this year’s lush fruitless bramble of primocanes should yield some fruit next year, but its root stock will also put up more primocanes next year, which may explain why some blackberry brambles I watch never seem to produce fruit. It also may be that black berry floricanes especially sensitive to cold, much more so that red raspberries for example. And after last year’s cold winter, I notice that the wild raspberry crop this summer has far surpassed what it usually is, and blackberries, sadly are harder to come by in my yard.

I grow cultivated raspberries, enjoying them from the freezer all winter long. The blackberries though, have defied my attempts at domestication. And once in a bumper crop year I froze some, only to find them disappointingly tasteless when thawed in December. For me blackberries are a fruit that demand to be appreciated on their own fleeting terms—on the side of a dirt road, ideally warmed by the sun, going directly from cane to mouth, staining fingers inky purple. Enjoy them in the present as a foraging wild animal, it’s a marvelous way to spend the last few days of summer.


GoBotany is a great place to start learning about the different Rubus species in New England

Saturday, August 22, 2015

Arctic Oil Drilling and Climate Change: Connecting the Dots

Note: This program first aired August 22, 2015.
If you haven’t noticed lately, its been kind of hot here in Maine. Hot like it hasn’t been all summer, or even in a year or two. While the rest of the world has been heating up, the Northeast has generally been running a bit cooler than most everyone else. We knew that for sure last winter, but the same has held true for the past couple of summers as well. Exactly why we’ve been cooler while everyone else has gotten hotter, as predicted by climate models, is not entirely understood. The wandering of the polar vortex that has graced our past two winters results from latitudinal changes in atmospheric pressure gradients, which change the jet stream, allowing it to run more north and south than the typical east and west. The summer coolness may just be coincidence, or may not. Rapid melting of Arctic sea ice and the Greenland Ice sheet have put large quantities of cold fresh water into the north Atlantic and changed aspects of the circulation of the Gulf Stream. Less warm water is going north, and less cold water is coming south. The resulting cold area in the north Atlantic may be having something to do with our coolness relative to the rest of the world. Or not. It just isn’t clear.
While we’ve been living in our cooler than average bubble here in Maine (present heat wave notwithstanding), temperatures on the rest of Earth have been rising. In fact the first half of this year has been the warmest on record, wiping out the “warmest year on record” status held by last year. And we know why this is, we’ve talked about it ad nauseam here on the show before. Increased levels of atmospheric green house gasses are trapping more and more heat in the Earth’s atmosphere. The primary green house gas is of course, carbon dioxide—one of the key nutrients necessary for photosynthesis and one of the products of energy liberating chemical reactions, like deconstructing glucose for metabolic energy or burning oil, coal or gas to yield mechanical energy. Anything we do that diminishes photosynthesis or increases energy liberation increases carbon dioxide production.
As has been clear from the past two winters here in the northeast, the impacts of climate change are not distributed uniformly across the surface of the Earth. We were buried under feet of snow, and when it wasn’t snowing it was well below zero, while my uncle in Alaska dealt with rain and temps in the 50’s all winter. One of the regions being hardest hit is the Arctic, a region of the world that has been an ice covered ocean for at least 700,000 years, if not more. Each summer the sea ice melts a bit, and each winter more ice forms. Lately though, due to all this carbon dioxide mediated warming, more and more ice has been melting in the summers, and less is refreezing in the winter. The ice is getting thinner, and the overall coverage is diminishing. This is problematic for many of the organisms that make the Arctic their home, as well as for the havoc that it wrecks on global weather patterns (Snowmageddon anyone?). There are some people out there though, who think this lack of Arctic ice is pretty good news. The petroleum company Royal Dutch Shell has been working for many years to secure all of the equipment and permissions required to begin exploratory well drilling in the Arctic Ocean north of Alaska. Because this is US territorial water, it required the permission of the federal government, which it just received. 
One of the things we talk about when looking at climate change is the feedback loop. Feedback is when one thing impacts another, which can then impact the original event which can then impact the secondary event, and on and on. What we have set up here in the Arctic now is a feedback loop. We burn fossil fuels and pump carbon dioxide into the atmosphere, which warms it, which melts the Arctic sea ice, which opens access to the Arctic Ocean for offshore drilling, which gets us more fossil fuel. Perfect. I feel like that character in the movie Zoolander, who, at his wits end screams out “I feel like I’m taking crazy pills!” Aren’t we worried about the impacts of climate change?  Then why are we green lighting a scheme to get even more climate change causing oil? Not to mention the potentially horrific impacts of an oil spill in the Arctic. Someone didn’t connect the dots here. As we stew in our 100% humidity here in Maine, for a few weeks we join the rest of the world in feeling the heat. I suspect that when President Obama visits the Arctic later this month, he will be feeling the heat as well.
Its official—the first half of this year is the warmest on record (world wide)
Images of temperature anomalies (variations from average) from NOAA:
Wow, words can hardly express my delight in finding this parody site: #failbetter
Arctic sea ice current conditions:
Why did Shell get a permit? Democracy Now interview:

Saturday, August 8, 2015

Tick Seasonal Patterns

Note: This program first aired on August 8, 2015.

Ticks, though nearly universally reviled for their parasitic eating strategy and disease carrying potential, have a pretty amazing life history. A little knowledge about their seasonal cycles can even help you understand why they show up when they do, why they seemingly disappear for a while and when you need to be most concerned about having them around.

Here in Maine, the ticks we are most worked up about belong to the genus Ixodes. There are several species, only one of which carries the most common tick borne illness in this area, Lyme Disease. Ixodes scapulara is the deer tick or black legged tick, and that is the one to keep track of, so it’s the one we will use as our example of tick life history.

In Maine the deer tick’s life can take upwards of 2 years to complete. It starts as an egg, hatching in August or September, essentially the end of the growing season. What emerges from the egg is called the larval stage; they are tiny, very hard to see, but because they are larval, you don’t need to fly into a panic if you some how notice you have been bitten by one. Larval tick hatch from eggs in a pure state—meaning, even if their mother was carrying the bacteria that causes Lyme disease, the bacteria does NOT carry over into the eggs. Newly hatched larval ticks don’t have the bacteria in them yet. So if you get bitten by one a. you probably won’t notice because they are so small, and b. it doesn’t matter for Lyme disease, since they can’t transmit it to you anyway. In late summer/early fall these larval ticks are primarily feeding on rodents like white footed mice, shrews and chipmunks, and it is from these animals that they first contract the Lyme causing bacteria. White footed mice are the primary reservoir for the disease, not deer like so many people think. After the larval ticks have fed in the fall, they over winter engorged in the leaf litter and eventually molt.

The next spring the ticks emerge as newly molted nymphs. The nymphs need to eat in the spring, and when everyone freaks out about the sudden flush of ticks as soon as things warm up, these are the ticks they are freaking out about. As we just learned, these nymphs could have acquired the Lyme causing bacteria from their first meal the fall before as larvae, and it is from getting bitten by these nymph stage ticks that most humans pick up the Lyme causing bacteria. After these nymphs feed in the spring, they molt into adults.

Adult females need to eat again before they can lay eggs, and it is typically fall before they do their biting. They over winter fully engorged, and emerge in the spring to lay their eggs, thus completing their life’s work. So to recap: larval ticks feed in the late summer, nymphs in the spring/early summer, adult females later in the fall. Only the nymphs and adults can transmit disease, with nymphs doing the lions share of infecting. The other commonly encountered ticks here in Maine are wood ticks, the adults of which are the ones you might find trying to bite you in late spring or early summer. Now that it is August, I hardly see any of these. Now I am just waiting for fall and the emergence of the adult deer ticks. It seems strange to mark the passage of the seasons by the different life stages of a creature so despised, but knowing the rhythm of the ticks not only empowers me but adds yet another layer of understanding, another layer of connection between myself and the rest of nature.


Comprehensive list of ticks in Maine from Maine Medical Center Research Institute:

Saturday, August 1, 2015

The Sophistication of Ticks

Note: This program first aired August 1, 2015.

Ticks seem to be everywhere this season, in the woods where I walk, on my dogs and cats, crawling up my pant legs, and this past spring, all over Facebook-everyone was posting about the spring emergence of the ticks. And I get it, Lyme (not to mention all the other tick borne diseases) is sometimes difficult to treat and can be life altering for some of sufferers. But this isn’t a program about health or disease, it’s about the natural world, and for better or worse, ticks are part of that world.
Ticks are arthropods, a group of animals that is characterized by having a chitinous exoskeleton and jointed legs. Insects and crustaceans are classes of arthropods we are all familiar with. Ticks are in the class Arachnida with spiders and mites, a sub group of arthropds that typically have 8 legs and specialized mouth appendages. In reading up on ticks I learned some things that are fascinating, and so even though they are one of the most hated groups of animals around, I want to share what I found out.
Ticks, like many insects, undergo incomplete metamorphism, which means that they hatch from an egg into a form that is similar to the adult, usually just smaller and sometimes with less well developed appendages or body parts. For example the deer ticks we worry about so much here in Maine have only 6 legs in this newly hatched stage. Typically this stage is called larval, though you shouldn’t confuse it with the larval stage of an insect like a butterfly that undergoes complete metamorphism. In those organisms “larva” means caterpillar or grub or maggot, something that looks nothing like the adult. Baby or larval ticks look like tiny ticks, and they feed on the same thing as adults; blood. Tiny larval ticks require a blood meal before they can grow into the next stage of life, once they have eaten, they molt their exoskeleton and emerge as a nymph. Nymph ticks often look just like adults, only smaller. They also need a blood meal in order to molt and grow into the last stage of life, the adult. The job of the adult tick is to mate, and only the female needs a blood meal, so that she can lay her eggs, and the cycle starts over. So, egg hatches, larvae, feeding, nymph, feeding, adult, feeding; they eat three times (and only three times) during their lives which can last over a year here in Maine.
Three times in a year and a half, that isn’t much food, for that much time. Each time they bite they have to get enough food for months. How they do it is really interesting. We all know that ticks embed themselves into the skin of their victim, staying attached for days while they suck out the blood they need to further their life cycle. Ticks have specialized mouth parts that work in tandem, one part ratchets while the other part drives deeper into the skin. These parts are lined with reversed direction barbs, so they can’t simply slide back out. Once the mouth parts are fully embedded, no energy is required for the tick to stay there and feed.
Ticks are very small animals, yet they need to get enough food to sustain them for months from just one feeding. If you have ever seen an engorged tick on your dog or cat, all shiny and gray and swollen, you know that ticks have an abdomen that can stretch to hold a large volume of blood. Even more remarkable though is the level of sophistication the ticks have when feeding. As the ingest blood from their host, it is immediately digested and separated out. Ticks keep the red blood cells, apparently the most nutritious fraction of blood. All the rest, the plasma fluid, salts, other blood cells, gets excreted back into the host’s body. So the ticks suck your blood, take only the best parts, and spit the rest back out, thus concentrating their meal. That is how they are able to feed once and live for many months on that one meal. And that is why, for animals that have a high tick burden, anemia can become a real problem.
Detested, persecuted, hated; ticks get a bad rap in the animal world. They are only doing what we all are though, living the only life they know how to lead, fulfilling their biological destiny along the way.
Tree of Life site for Arachnids
Comprehensive list of ticks in Maine from Maine Medical Center Research Institute:
A Maine based company with lots of info on their website:
Thank you Ed Yong for citing this article (though no one seems to have looked at how they detatch themselves and get those amazing barbed mouthparts out of your skin):

Saturday, July 25, 2015

The Principles of Natural Selection as they apply to Baby Birds

Note: This show first aired July 25, 2015.
Natural selection is the mechanism by which evolution takes place, and by evolution, I mean the change in genetic material in a population over time. That change over time is thought to make populations more robust, more “fit”, fitness meaning more successful reproductively; and successful reproduction is the name of the game when it comes to life on Earth.

Darwin’s theory of evolution by natural selection is based on three simple premises: that more individuals are produced than can survive, that there is variation in the traits of those individuals, and that the individuals with the traits best suited for survival and reproduction in the environment will survive. The genes that code for the successful traits get passed on. Genes that code for less successful traits get passed on far less frequently, and eventually disappear from the gene pool. That is how over time, the genetic makeup of a population changes.

We’ve been talking the last couple of weeks about an ill fated pair of baby birds, they were discovered tumbled out of a nest that was blown out of a tree, and birds and nest were replaced into said tree as best an anxious adult and curious child could do. Upon first check up, the baby birds were discovered to be out of said nest again, and replaced a second time. Upon second check up, both babies were gone, as were the parents. In some ways the experience feels like failure, but as I talked about last week, the odds for those babies were never very good even in the best circumstances, which brings us to that first tenet of Darwinian evolution: more individuals are produced each generation than can survive. So why didn’t these birds survive? 

The second tenet of natural selection states that there is variation in traits among individuals in a population. Among all of the chipping sparrows in the northeast, some make very strong well protected nests, others make flimsier ones. Some choose nest sites out of the prevailing wind, others choose more exposed shrubbery. Nest building is a very instinctual behavior in birds (though there are studies that show that as some birds practice, their nests get better, indicating that there is a significant learning component to nest construction as well). The instinctual part of nest building results from genetics, some birds have genes that code for proteins that end up directing cells to do X, other birds may have genes that code for proteins that direct cells to do Y. If X causes the nest to be built in a very secure location, and Y causes the nest to be built in a more exposed location the genes have significant implications for the fitness of the individuals. Those birds may survive, but where they locate their nests impacts the survivorship of their young, and whether or not the genes of the parents get passed on into the chipping sparrow gene pool or not. If they can’t successfully reproduce because they keep building their nest in an unsuitable place, they are a genetic dead end, which brings us to Darwin’s third tenet of natural selection. Genes that code for successful traits get passed on, genes that code for less successful traits eventually die out.

There is one more factor beyond how successful or not the traits your genes code for are, and that factor is simple bad luck. Sometimes organisms are doing all the right things, have robust traits, and high survivorship, when bad luck strikes. In the case of birds, they could be in a tree that gets cut down, or in a tree that gets damaged by lightening or a falling nearby tree, things that don’t have anything to do with their nest location and building skills. And that is the other hard truth about natural selection, there is a large and strong random component to it. Just as the mutations that give the gene pool variation are random, so are the incidents of “bad luck” that can change the distribution of genes in a population without respect to their impact on fitness. These shifts in gene frequency due to bad luck (or being in the wrong place at the wrong time) are called genetic drift, and the smaller the population size, the bigger an impact it can have. 

The mechanism of natural selection cuts a broad and unforgiving swath through populations every reproductive cycle, and while there can be bad luck, there is rarely good luck. The modern human experience of the world is so different from this that it is hard for us to remember. In nature, the default is failure. Keep this in mind as you look around you and recognize what you see for what they are-the chosen few, the rare success stories amidst nearly infinite attempts at life.


On birds, nests, instinct and learning—this well publicized study came out in 2011 and challenged the long held assumption that bird nest building is entirely instinctual

Wednesday, July 22, 2015

First Year Bird Mortality

Note: This program first aired on July 18, 2015.

Today I have an update to the story I told last week. If you missed it, my niece and I recalled the experience of finding a bird nest that had been blown out of a tree. It was on the ground, and around it were the baby birds that had been in it. We put the birds back in the nest and put the nest back in the tree the best we could, hoping the parents, who were anxiously flitting around the tree chirping, would be able to resume their parenting duties. We realized that this was the right thing to do, even though emotionally it was really hard, our nurturing drive kicked into over drive and we just wanted to take the babies home to “save” them.  And I wish I could give you a happy ending to last week’s story, but the fact is, I can’t. When I went back the next day, the nest was empty, the babies gone, and the parents, if they were around, were silent. When my niece called later for an update, I had to tell her the truth. I was anticipating some melodrama, but instead she said so matter of factly “I kind of knew that was going to happen”, and that was the end of it.

You may wonder, as I have, if putting the babies back into the nest and leaving them was indeed the “right thing to do”. After all, even though we did the right thing, we left them with their parents, it didn’t work out. The reality is that even though they had the best chance of surviving under the care of their natural parents, that doesn’t mean that chance was very high to begin with. This is another one of those dirty secrets of nature that most of us never think about. Most things that are born don’t make it out of childhood. The average mortality for first year birds can be as high as 90%. For typical passerines or perching birds, juvenile mortality in the nest is around 50%, that is before the young even fledge. Nest predation and weather related accidents account for most of this mortality. Once the young fledge and eventually learn to take care of themselves, mortality pressure doesn’t let up but it changes form some what. Young birds aren’t as successful at feeding themselves, so starvation gets added to predation as another factor in first year bird mortality. Most of us, watching our back yard bird feeders, never have any idea the odds are so poor.

But what is the alternative? If a pair of robins in your yard has two successful broods a year (Robins are thrushes and will have a second and even occasionally a third brood in a single season if time allows), and each brood consists of 4 young, at the end of the season where there were 2 robins we now have 10. An environment that easily supported 2 robins may not so easily support 10. And what of next season, if all 10 of those robins were to survive and reproduce? The world would soon be flooded with robins, the environment denuded of all appropriate robin forage. It isn’t even a realistic scenario, and we all understand that. But in order to have the realistic scenario, a relatively steady state of robin population in our back yards, young robins die. Old ones do too, but robins are adapted to have more babies hatch than old birds dying, because the young are such easy prey. If you have many offspring, hopefully one will make it to old age.

Humans used to live this way too. When child mortality was much higher than it is now, women gave birth to many more children. As health care has improved and child mortality has dropped dramatically in most parts of the world, the number of children a woman gives birth to has dropped as well. We no longer have to hedge our bets like the birds do.

Most birds will try again and renest when they experience a nest failure, like those chipping sparrows at my neighbor’s house. There’s still a chance that we will see their young flying this summer, just not the young from that ill fated nest. And when I see an adult bird, I’ll see all of its nestmates now as well, the ones who pulled nature’s short straws, enabling life as we know it, to go on.


Uncited but with interesting math:

Uncited but good ideas (personal blog of a bird researcher)

The free shelf at my local academic library yielded a 1975 copy of Wallace and Mahan’s An Introduction to Ornithology 3rd Ed, which has been a great source of foundational material!

Wednesday, July 15, 2015

What do do with a baby bird

Note: This program first aired on July 11, 2015.

This week's show featured my niece Caitlin as we described the experience of finding a bird nest on the ground one windy day, and then finding the baby birds that went with it. We talked about what we did and how it felt, and how doing the "right thing" was hard.

The internet is a great resource for leaning about what to do in that situation, if you go to a reputable site. The internet can also trip you up (as Caitlin said to me that night "the internet lies!"), so you have to be careful about who you listen to.

Some of the sites I used to figure out what to do are listed here:

There are lots of Wildlife Rehabilitators in Maine, but they don't all take birds (that requires a federal permit. If their listing says they don't have a permit, that means they can't take birds).

The most well known bird rehab facility in Maine is Avian Haven in Freedom (Waldo County).

Remember, all migratory non game birds are protected by federal law. It is against the law to possess any bird or bird part (living or dead) without a federal permit!

Dance of the Sand Worms

Note: This program first aired July 4, 2015.

A few weeks ago, I got a call from my nearly 4 year old nephew during dinner. I could hear the excitement in his voice as he shouted into the phone about seeing worms in the water at the town dock. I asked him what color they were and he said they were all colors. This brought back a memory from my own childhood, a memory until this moment I wasn’t even sure was real. I remember seeing huge iridescent blue green worms swimming at the surface of the water, and then seeing them washed up dead on the beach the next day. I saw them that one time, and never again, causing me to think I had either imagined it or witnessed something very rare. Hearing my nephew’s excitement a couple fo things became clear, what I saw was indeed real, and that now my family has an official childhood rite of passage: witnessing the spawning swim of the sand worms.

Sand worm, rag worm, clam worm, these common names all refer to various species of polychaete worms found in coastal areas throughout the north Atlantic. Polychaetes are marine segmented worms, meaning their bodies are divided up into hundreds of discrete segments. Believe it or not this body structure represented a big leap forward in terms of evolutionary complexity. Polychaete worms are an incredibly diverse and successful group of organisms, there are over 100 species listed for the Gulf of Maine alone.

The worms I saw as a child, and my nephew saw this spring are Alitta virens, sometimes known as the king rag worm, or sand worm. They live in burrows in low intertidal or sub tidal sand or mud. The burrows are U shaped, with each end of the U an opening  at the surface of the sand. The worms spend most of their lives in these burrows, pumping oxygenated water through them so they can breathe (and a neat side effect is the diffusion of oxygen into otherwise anoxic sediment. The oxygen burrowing worms draw down into the sediment fuels an entire microscopic ecosystem). They stick their fearsome heads and sharp black teeth out of the burrow to feed on various small benthic sea creatures, and are said to sometimes scavenge omnivorously. Rag worms are among the most long lived of polychaetes, some are thought to reach the ripe old age of as much as 7 years. In the end though, regardless of how old they get, their fate is the same. This group of polychaetes practices what is called “semelparity”, meaning they reproduce once, and then they die.

As I said, these worms spend their lives in their burrows, only occasionally leaving to crawl along the bottom to find better digs, otherwise they are in the sediment. Things change however, when it is time to mate. The males undergo epitoky, their bodies change shape and structure in preparation for mating. They turn shimmery blue green and learn to swim, and around the new moon, they swim to the surface at high tide and release their sperm into the water column. That sperm makes its way down to the females who have remained in their burrows. They fertilize the eggs they have spent nearly a year developing in their bodies. Once the eggs are fertilized, the female excretes them on the surface of the sediment outside her burrow, where they develop, hatch and start a new generation of sand worms. After shedding sperm, the males die. After laying the eggs, the females die. Such is the life of a sand worm.

The moon is involved because the worms, both male and female are highly sensitive to photoperiod, and the development of the eggs begins a year before mating in response to changes in day length. Something about the combination of warming water in the spring, lengthening days, and darkness at night tells the males that the females are ready, but as far as I can tell, we can’t know for sure when the magic will happen.  That is why it is such a good idea to be outside as much as you are able. You never know when you will stumble upon a certain flower blooming, a case of tiny spiders hatching, baby birds fledging, a lynx track in the snow, or hundreds of two foot long blue green worms swirling in the water doing their once in a life time dance. 


Everything you want to know about clam and blood worms:

All about Annelids, from the Tree of Life:

Actually, even more that you might want to know about polychaets, from and OLD Woods Hole guide:

 On lunar impact of breeding (but not of worms specifically)

Tuesday, June 2, 2015

Alewives and People

Note: This program first aired on June 6, 2015. 

It’s not often you find your self in the presence of something overtly holy, and by holy I mean elm seedling sprouting out of cracks in stream side rocks. I mean young royal ferns unfurling in the rain. I mean flowing water crowded with the gray and silver bodies of fish, fat with fecundity and virility. If you go way way back the word holy derives from words in Old English meaning “uninjured, sound, healthy, entire, complete….things that must be preserved intact, that should not be transgressed or violated”. And that is what I felt when I went to the outlet of Patten Stream in Surry Maine and saw the pools and eddys fill with alewives as the tide came in.

If you haven’t yet been to the outlet of Patten Stream, it is a good place to see the alewives make their migration inland in the spring. It is also a good place to see community in action. You see, the alewives that have been breeding in Patten Pond hundreds, maybe even thousands of years haven’t had an easy time of it in the last few decades. The rebuild of a large road culvert over Patten stream changed the way the water flowes over a ledge, creating a steep high energy waterfall that makes it virtually impassable for all but a few alewives. Alewives are small sea run herring and while they can swim well, they don’t have the gymnastic jumping ability of some other sea run fish like salmon, so even small ledges can stop them. The Department of Marine Resources noticed a decline in the number of alewives in Patten Stream and Pond and tried to solve it by stocking the pond with hatchery raised baby alewives. A group of citizens took a different approach, understanding that the issue wasn’t population, but barriers to reproduction. And the barrier was the road culvert. So what do you do if you are a small group of concerned citizens that sees a problem that will take a huge amount of money and infrastructure and beurocracy to fix, money that will take years to secure, plans that will take years to develop? You purse all of that, but in the mean time you do what you can with your own two hands. At Patten Stream not only did I see the pools and eddys full of plump alewives, but I also watched as a group of volunteers stood in the stream on a cool rainy day and transfered fish up and over the offending ledge by hand. In a team of 4 to 5 people they would pass a long handled dip net containing 10 to 20 fish fire brigade style, over and over again, as the crowd of fish in the pool below thickened and waited patiently. It was inspiration and heart break in equal measure. The fish way that has been years in the making should be built later this summer, so hopefully next spring those volunteers will be out of a job.

What I learned that day, was that I am not the only one who sees those fish and that stream, as holy. The community members who saw the problem and put their hands to work solving it, the crowd of people like myself who came to watch, the loon swimming in the harbor just off shore, the seals lolling about patiently at the surface just behind her, the osprey and eagles that fly above the harbor and wait in the trees above the stream, the bears and raccoons and other forest animals that feed on the fat fish on their way up stream or the spent ones on the way back down, the cod and haddock that eat the young alewives at sea, we are all connected by something “that must be preserved intact, that should not be transgressed or violated”, something holy. Those fish are a unifying force, you can feel it when you stand there and watch them. It is a force that is feeling more and more unstoppable.

Margaret Mead said “Never doubt that a small group of thoughtful committed citizens can change the world; indeed it’s the only thing that ever has.” Sometimes all that group of citizens has to do is give nature a little help, and she’ll do the rest. Those alewives know what do to. And if you’re not sure what to do, go watch them; they’ll tell you.

You can find a transcript of this program, as well as contact information and references on our website, look for the Show Notes link at, where you can also download the show as a podcast or listen to it on demand. Our music is from Stanley Watson’s Portrait of Don Potter, performed by MDI guitarist Kevin Morse. Thanks for listening, and as always, join us next week for another look at the world around us.


Here’s what the internet told me about the etymology of holy:

From the Ellsworth American:

Iceland Biology

Note: This program first aired on May 30, 2015. 
Today we hear more about Iceland, that mysterious high latitude island formed from volcanos, covered in sheep, and home to elves and other hardy folk. It takes a while to sink in while you are driving around, that you aren’t going to see any animals in the road, unless they are domestic sheep. Iceland has only one native terrestrial mammal, the arctic fox, and while the population is considered viable, they aren’t especially common.

So why no other native mammals? Reindeer were introduced on purpose, and mink accidentally, escaping from fur farms. Mice and rats accompany people wherever they migrate, but only the arctic fox, and humans, got to Iceland on their own. Why, for that matter, such low terrestrial biological diversity overall? Iceland has the distinction of having no amphibians or reptiles. Of the 1100 species of insect, the flies are the most numerous, followed by beetles and bees, while there are no ants or butterflies.

In the plant kingdom things are similar, there is relatively low diversity in vascular plants and bryophytes. The only native trees are a birch, a willow and the rowan tree, a species in the same genus as mountain ash. Only 10 species of passerines, perching birds, nest in Iceland. Even if you know very little about birds you could probably name 10 passerines without much trouble. The freshwater systems on the island host only 5 species of fish.

The answer of course is that Iceland is very isolated, and only recently unglaciated. The same ice age that covered much of North America, including Maine, covered Iceland as well. The difference is that once the glaciers retreated from Maine, Maine was connected to an entire continent populated by organisms ready to move in as climate allowed. Iceland found itself in the middle of the high latitude North Atlantic Ocean, and while the ice that connected it to Greenland and northern Europe allowed the hardy little Arctic Fox to tip toe its way across the ocean, nothing else made the icy crossing.

Only things that can travel by air, water, or animal can get to Iceland. Spores and very light seeds can be blown there if they get carried very high into the atmosphere. Other seeds can float and survive the ocean crossing if they are tough enough. The only animals seen on land that are found in relative abundance in Iceland are birds, and mostly sea birds at that. Which should be no surprise, as these animals routinely migrate thousands of miles, and are not stopped by air or water. The very lack of a land bridge for terrestrial migration is the reason they fly to Iceland. Essentially no land mammals means no predators; Iceland is an excellent place to lay some eggs right on the ground and call it a nest.
What Iceland does have in spades is marine biodiversity, hundreds of species of fish are found on its continental shelf, and over 100 species of algae grace its coastline. 15 or more species of marine mammals are found in its waters. What makes Iceland such a hard place to colonize, its location and latitude, make it a perfect spot for marine productivity. It lies right on the boundary between the polar and subpolar ocean currents, warmer water from the Gulf Stream and North Atlantic current especially warm the southern coast, while colder arctic water cools the north east.
The interplay between these two, combined with the large continental shelf extending out away from Iceland, mix the ocean and distribute the nutrients that drive productivity.

Humans have been exploiting this productivity for over 1100 years, Iceland was first settled by Vikings in 870 AD. Humans have been impacting the landscape ever since. The most significant environmental impact during Iceland’s 1100 year history has been soil erosion, primarily due to changes in vegetation that result from grazing. The shrubby forests found on the island retreated, and currently the vast majority of the island is used as open range land for the thousands of sheep that are raised there. The erosion impedes recovery of native vegetation, and the mild climate and short growing season don’t help either.

All of this dawns on you as you drive around the island, seeing birds everywhere, sheep and fences, but nothing else. There are vast stretches of land inhabited only by moss. After several days of just grass and stone I felt an explosion of sweet relief when we drove through some trees. Iceland is surrounded by hundreds of kilometers of water, and just kisses the Arctic circle. Biology has cobbled together an entirely respectable community of organisms to live on this chunk of rock in the middle of nowhere. I encourage you to check it out.


The biological diversity of Iceland