$$ Eubacteria

Well, I admit it: I am just not as interested in microscopic organisms as visible ones, and thus am as guilty as anyone of taxonomic chauvinism. I just want to be able to look at stuff and draw it; that’s my excuse. What’s yours?

Couldn’t find any MICROBES so I drew some cashews

But I am working on it. I’m learning a lot of fascinating stuff about Eubacteria and Archaea, two of the three domains of life. Particularly thought-provoking is the idea that some of them engulfed others of them to create the ancestors of the third domain, the more interesting one that includes everything from algae to avocado to fungi to fish to humans. Eukarya!, as Archimedes remarked, or something like that.

Before I bring this brief note to a close, I know what you're thinking. Why is the hybrid domain called Eukarya, when “Euchaea” would have made a superior portmanteau of the words Eubacteria and Archaea? It is too bad that we are not in charge.

Climbing around the tree of life

Quercus rubra

I’m systematically studying systematics—how all living things on Earth are related—so herewith begins a series inspired by exploring the tree of life.

Yes, I claim to be approaching this exploration with a system, but it might be useful to know that my systems rarely involve sticking to recipes. Rather than gearing up to ascend the tree in an orderly fashion, expect to backtrack and change directions, jump squirrel-like to distant branches, and frequently fall off. The real plan is to spend much more time on tangents than actual taxonomy.

But we know the tree is there; we can come back to it. It’s a guidepost, a framework. It keeps contained and organized a vast realm of biological inquiry that would otherwise be completely overwhelming. It’s a lot like my 3,400-item hierarchical to-do list, which I edit and reshuffle ad nauseam while only occasionally completing an actual task. As mighty as my Workflowy list undoubtedly is, the tree of life has it beat with something like 1.8 million species described and 10 million estimated—or maybe 3 trillion, if that makes a difference—not counting untold oodles of extinct ones.

Something I find exciting about this tree is that it’s a new way to orient oneself as a naturalist, despite the fact that the biodiversity it encapsulates is 4 billion years in the making. We may have been identifying and categorizing living things for the entirety of human existence, but we have only had the concept of an evolutionary tree since around the time of Darwin. And the tree itself has evolved dramatically as taxonomists hone the ability to compare organisms at a molecular level. Only within my lifetime has it grown into its current triadic shape, dividing life on earth into three major superkingdoms or domains or whatever you want to call them: Eubacteria, Archaea, and Eukarya. (I’ll start with Eubacteria in the next post, if I stick to the recipe, at least.)

Tamiasciurus hudsonicus

This very moment, phylogeneticists in our midst are pooling information from 4,185 studies and 148,876 species (and counting) in the effort to refine not only the branching patterns of the tree but also the timing of those splits between lineages, some of which diverged hundreds of millions of years ago. Regardless of how accurate all of that is at this point, I like having such a tree to think about. It lends an expansive dimension of time to the landscapes and living things I see spread out over global space. It gives me a sense of the family relationships that intersect with the ecological ones I can observe myself. It’s a Y axis to my X axis of wandering around outside sketching stuff. Lest we fall out of the tree prematurely, I’ll stop here.

Mismatches from climate changes

I drew this to illustrate another Forum paper for the scientific journal Oikos. Here is a summary of the study, “Why sex matters in phenological research” (by Nakazawa et al.):

As climate change shifts the timing of the seasons, it messes with different organisms in different ways—which can disrupt the way they interact. A predator might emerge before its prey does, for example, creating a trophic mismatch. Males and females of the same species can get out of whack, too, to the potential detriment of the next generation.

These Forum authors confront that idea of “sexual mismatch,” pointing out that males of many species gear up for mating before females do—or vice versa—as each sex responds differently to environmental cues. Their model shows that both sex-specific timing and trophic timing play important roles in the dynamics of a population.

But their literature reviews find that sex-specific information from the real world is scarce. Among other data limitations, studies of breeding cues tended to be male-biased for birds and mammals and female-biased for fish and insects. Notably, males had more variable timing than females for several species where the two sexes look different from each other—contrary to a conventional view that females are more likely to shift their timing.

Speculating that sexually dimorphic species may be especially vulnerable to a changing climate, the authors outline a more sex-conscious research agenda for the future (including collecting sex information during population monitoring, and using eDNA to gauge sex ratios) to better understand the ecological impacts of climate change.

Fishcasters

I wrote a story for Hakai Magazine about how US and Canadian herring fisheries are (and aren’t) paying overdue attention to warnings from seabirds.

Islands of domestication

I drew this to illustrate another Forum paper for the scientific journal Oikos. Here is a summary of the study, “Insularity and early domestication: anthropogenic ecosystems as habitat islands” (by Robert N. Spengler III):

Maybe humans take too much credit for domesticating plants and animals. This Forum paper argues that the human-friendly qualities of our pets, livestock, and crops could have arisen without selective breeding or other human-centric mechanisms that are usually assumed. Instead, it explores an ecological mechanism: the island syndrome.

Think of early farms and villages as islands. The author draws parallels between the processes of domestication and island evolution, suggesting that the same ecological forces may be responsible for both. Both island plants and cultivated crops tend to have bigger and less dispersible seeds than their ancestors. Animals on islands and in human habitats can lose flight ability, fear responses, and patches of pigmentation, among other changes.

Why such parallel patterns of evolution? It could be that when plants and animals find their way to islands or other insular habitats—ranging from early villages to modern cities—they are released from predation and competition pressures. Domestication scholars and island biogeographers would benefit from comparing notes, the author concludes.