Recent reading: 18 March 2022

“Library” (Flickr: a.canvas.of.light)

In the last fortnight, I saw one long-gestating project finally published, and got to be a small part of the publication of what’s arguably the biggest-ever study of adaptive evolution. I subjected an SUV full of students to a botany-themed playlist on the way to a walk through Joshua tree woodlands; and spent a big part of Monday afternoon guiding some of those same students through keying out some lovely spring-blooming plants. My university also formally invested a new President, so I spent a big chunk of my Monday morning dressed like I was going to preside over court. The natural world is flowering, campus is as busy as I’ve seen it in ages, and science is actually getting done in the sense that it’s “done” when it’s published. Is this … normality?

Anyway here’s some of what I’ve been reading, recently:

Henry GA and JR Stinchcombe. 2022. G matrix stability in clinally diverging populations of an annual weed. bioRxiv doi: 10.1101/2022.03.08.483458

Measures covariance of traits in Ipomoea hederacea, ivy-leaf morning glory, in greenhouse-grown samples taken from the northern edge and the center of the species range, and tests whether the major axis of genetic covariance (gmax) predicts between-population differences, as expected if divergence is along “genetic lines of least resistance”. A subset of the focal traits, to do with flowering and flower structure, have been previously shown to vary in north-south clines across the range, while growth and seed mass do not.

  • The northern-edge populations had somewhat lower trait variation and lower heritability.
  • Populations had relatively low variation in the direction of between-population clinal divergence — that is, clinal divergence doesn’t seem to reflect within-population “lines of least resistance”.
  • The most variable population is polymorphic for leaf shape, which is Mendelian — interesting possibility that variation in general is promoted by balancing selection for that trait.

Ortiz-Barbosa GS et al. 2022. No disruption of rhizobial symbiosis during early stages of cowpea domestication. Evolution doi: 10.1111/evo.14424

Cowpeas apparently represent an intermediate stage of domestication, still experiencing a bottleneck associated with selection of desirable alleles from the wild source population. The authors compare domesticated cowpeas with wild relatives to identify what alleles have been selected so far, and whether domestication has reduced reliance on (and adaptation for) management of symbiotic nitrogen-fixing rhizobia.

  • SNP data identifies two domesticated gene pools that differ in their likely geographic sources.
  • Loss of genetic variation in the process of domestication seems to be pretty minimal.
  • Experimental inoculation with N fixing and ineffective rhizobia strains shows domesticated genotypes initiate symbiosis more readily than the wild samples, but are still able to reduce nodulation with the ineffective strain — consistent with maintenance of sanctioning response against ineffective symbionts.
  • The greenhouse experiment also supports nonzero heritability for symbiosis traits in the domesticated lines, which can support further domestication selection for symbiosis efficacy.

Graves JL et al. 2022. Inequality in science and the case for a new agenda. PNAS doi: 10.1073/pnas.2117831119

  • Extensive discussion of inequities and disproportionate underrepresentation (mostly by race, but also by gender) in the scientific workforce, and their potential impacts on scientific thought and “productivity”.
  • “The objectivity and integrity (or lack thereof) of the scientific process is maintained by both individual scientists and communities of scientists. However, scientists are not persons with ideal intellects or moral virtues; they are imperfect human beings influenced by the societies in which they are raised and the social groups in which they live and work.”
  • “In short, we con- tend that there will never be science for the people until all the people are in science.”

About Jeremy Yoder

Jeremy B. Yoder is an Associate Professor of Biology at California State University Northridge, studying the evolution and coevolution of interacting species, especially mutualists. He is a collaborator with the Joshua Tree Genome Project and the Queer in STEM study of LGBTQ experiences in scientific careers. He has written for the website of Scientific American, the LA Review of Books, the Chronicle of Higher Education, The Awl, and Slate.
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