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.


References:

About Komodo dragons (who have exhibited parthenogenesis) http://www.ansci.wisc.edu/jjp1/ansci_repro/misc/project_websites_08/tues/Komodo%20Dragons/science.htm


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.

References:

NASA/Goddard Space Flight Center. "NASA studying 2015 El Nino event as never before." ScienceDaily. ScienceDaily, 19 October 2015. www.sciencedaily.com/releases/2015/10/151019182823.htm

Accuweather’s White Christmas prediction map http://www.accuweather.com/en/weather-news/white-christmas-2015-forecast-el-nino-odds-low-i95-dc-to-boston/54193099
The straight talk from NOAA http://www.elnino.noaa.gov/

Even straighter talk from the Weather Channel http://www.weather.com/forecast/national/news/winter-2015-2016-what-to-expect

There’s even an El Nino blog (it is really good, check it out) https://www.climate.gov/news-features/blogs/enso/what-expect-winter-noaa%E2%80%99s-outlook-reveals-what-conditions-are-favored



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.

References:

http://gcaptain.com/collision-course-with-a-hurricane-how-doomed-el-faro-met-its-end/#.VhzeKqJAWOU


http://gcaptain.com/we-wont-learn-anything-what-sank-el-faro-and-what-didnt/#.VhzfQ6JAWOU

On humans and seafood: https://www.psychologytoday.com/blog/lives-the-brain/201001/was-seafood-brain-food-in-human-evolution

UN on coastal population http://coastalchallenges.com/2010/01/31/un-atlas-60-of-us-live-in-the-coastal-areas/

http://stateofthecoast.noaa.gov/population/welcome.html

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.


References: 

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.
References:
Its official—the first half of this year is the warmest on record (world wide) http://www.weather.com/news/climate/news/earth-record-warmest-january-june-2015
Images of temperature anomalies (variations from average) from NOAA: https://www.ncdc.noaa.gov/sotc/global/201506
Wow, words can hardly express my delight in finding this parody site: http://arcticready.com/ #failbetter
Arctic sea ice current conditions: http://nsidc.org/arcticseaicenews/
Why did Shell get a permit? Democracy Now interview: http://www.democracynow.org/2015/8/18/obama_gives_shell_final_approval_to