The tenth episode of Planet Earth brings us to the biological communities I think of as “home” — seasonal forests. I grew up in rural Pennsylvania, with second-growth deciduous woodland literally in my back yard, went to college within sight of the Appalachian Mountains, and spent my first “real” job in field ecology surveying understory plant diversity northeast of Pittsburgh. Today, I’m working on the other side of the continent, but now studying some of the most widespread tree species in forests from the Pacific Northwest to the Yukon taiga. I could almost illustrate this entire recap with images from my personal Flickr stream.
Old-growth conifer forest (lots of Douglas fir, Pseudotsuga menziesii) around the Coquitlam Lake reservoir in British Columbia (Flickr: JBYoder)
I’ll try to resist the temptation.
We start at what is, arguably, the most seasonal of forests, taiga, where the growing season may last just a month. These snow-covered woods seems marginal, but boreal forests account for one third of the trees on the planet, Sir David Attenborough tells us. The newest comprehensive assessment of tree density worldwide, published last year, found that a median hectare of boreal forest has as many, or slightly more, trees than an average hectare of tropical forest — but it also puts the boreal share of the global tree count at closer to one quarter of all trees, and finds that “tropical moist forest” accounts for a slightly larger share.
Remember when I tried to start the twitter hashtag #pollinatorselfie last summer?
Well it’s not too late, and it turns out that snails, my beloved PhD system, can also be pollinators.
This is both promising for snails, and plants that need pollination everywhere!
Read about it over at AoBBlog.
A recent publication (B. Misof, et al. 2014. Phylogenomics resolves the timing and pattern of insect evolution. Science 346 (6210): 763-767.) takes on the herculean task of finding when insects first evolved. This is a particularly vexing question because 1) insects are squishy and don’t fossilize well, and 2) the vast majority of the species on the planet are insects. This is an insect world, we just live in it.
The paper was summarized BRILLIANTLY on WIRED (here). Including my favorite quote:
“Making sense of the diversity of insects in collections has traditionally been a task for a lone expert, usually specializing in just one subset of a group. They become so identified with their study organisms, they may be introduced as “The Ant Man” or “The Wasp Woman.” (No taxonomists I know wear spandex tights and capes to work, for which I am profoundly grateful.)”
Find out about when insects evolved, when they diversified (surprisingly, it started PRIOR to the radiation of angiosperms) and more.
Last week NPR posted an excellent article about what can only be the coolest pollinator. Ever.
“like a flip-flop that doubles as a beer bottle opener; an optical illusion; a labradoodle; a frenemy, the hummingbird moth falls into that cryptic category of transformers in life that are more than one thing” – Linton Weeks ” What Exactly is that Birdlike Thing?”
In my part of North America, spring is finally underway after a long slog of a winter. The trees lining the streets of my Minneapolis neighborhood are lacy-green with budding leaves, flowerbeds all over the University of Minnesota campus are yellow and red and pink with daffodils and tulips, and violets are popping up in the edges of lawns everywhere I look.
Of course, all of this colorful display isn’t for my benefit. Showy flowers are an adaptation to attract animal pollinators. Some flowers are quite precisely matched to a single species of pollinator, but most flowers have lots of visitors. These less specialized flowers are still adapted for their attractive function, though—and this is the origin of pollination syndromes.
One of your future colleagues in the Smith Lab, hard at work in the field.
Friend of the blog—and longtime collaborator of mine—Chris Smith recently landed an NSF CAREER grant for new research on the causes of evolutionary divergence within the Joshua tree-yucca moth mutualism—and he’s looking for a postdoc to help with it!
The proposed work will take advantage of new genomic resources for the genus Yucca—Joshua tree population genetics is about to get a lot more powerful than the 10 microsatellite loci I used for my dissertation research. And it will involve fieldwork in the Mojave Desert, which is objectively one of the most beautiful empty spaces on the map of North America. Chris is on the faculty of Willamette University, which is an undergraduate institution, so the postdoc position is also a unique opportunity to do basic research in close coordination with an undergraduate teaching program.
Moreover, I can personally recommend Chris as a mentor and collaborator—to the extent that I’ve turned out to be a pretty decent scientist, he’s one of the principal reasons why. (And to the extent that I haven’t, well, that’s a reflection on me, not him.)
The complete job description, and instructions on how to apply, are after the jump.
A Joshua tree flower, up close.
A huge diversity of flowering plants rely on animals to carry pollen from one flower to another, ensuring healthy, more genetically diverse offpsring. These animal-pollinated species are in a somewhat unique position, from an evolutionary perspective: they can become reproductively isolated, and to form new species, as a result of evolutionary or ecological change in an entirely different species.
Evolutionary biologists have had good reason to think that pollinators often play a role in the formation of new plant species since at least the middle of the 20th century, when Verne Grant observed that animal-pollinated plant species are more likely to differ in their floral characteristics than plants that move pollen around via wind. More recently, biologists have gone as far as to dissect the genetic basis of traits that determine which pollinator species are attracted to a flower—and thus, which flowers can trade pollen.
However, while it’s very well established that pollinators can maintain isolation between plant populations, we have much less evidence that interactions with pollinators help to create that isolation in the first place. One likely candidate for such pollinator-mediated speciation is Joshua tree, the iconic plant of the Mojave Desert.