Life cycles in major transitions, and some clueless critique

Jordi van Gestel and Corina Tarnita have published a ‘Perspective’ in PNAS, “On the origin of biological construction, with a focus on multicellularity“:

…we propose an integrative bottom-up approach for studying the dynamics underlying hierarchical evolutionary transitions, which builds on and synthesizes existing knowledge. This approach highlights the crucial role of the ecology and development of the solitary ancestor in the emergence and subsequent evolution of groups, and it stresses the paramount importance of the life cycle: only by evaluating groups in the context of their life cycle can we unravel the evolutionary trajectory of hierarchical transitions.

van Gestel 2017 Fig. 2

Figure 2 from van Gestel and Tarnita, 2017. Relationship between life stages in hypothesized life cycles of solitary ancestors and group formation in derived group life cycles. (Upper) Simplified depiction of hypothesized ancestral solitary life cycles of the green alga Volvox carteri, the cellular slime mold Dictyostelium discoideum, and the wasp Polistes metricus. Life cycles here consist of a life stage expressed under good conditions (black) and a life stage expressed under adverse conditions (green). For the latter life stage, we show an environmental signal that might trigger it and some phenotypic consequences. (Lower) Simplified depiction of group life cycles of: V. carteri, D. discoideum, and P. metricus. Developmental program underlying life stages in solitary ancestor is co-opted for group formation (shown in green): differentiation of somatic cells (V. carteri), fruiting body formation (D. discoideum), and appearance of foundress phenotype (P. metricus).

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Look what came in the mail yesterday!

Biological Individuality

A project started five years ago has finally borne fruit. In May, 2012 I joined a group of philosophers, historians, and biologists in Philadelphia for the Cain Conference “E pluribus unum: Bringing biological parts and wholes into historical and philosophical perspective.” The meeting was organized by Lynn Nyhart and Scott Lidgard, with the goal

…to pursue the question: How can historians, philosophers, and biologists help each other to understand part-whole relationships in biology, both today and in the past?

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AbSciCon 2017 day 1

AbSciCon logo

Yesterday was the first day of AbSciCon 2017 in Mesa, Arizona.

Phoenix is not my favorite town; it’s got all the brutal heat (and then some) that Tucson gets, without a tenth of Tucson’s charm. That said, it’s been fairly pleasant so far, only getting into the 80’s yesterday. The hotel restaurant is pretty lame, but there is decent food about a ten-minute walk away.

Yesterday started with a bizarre plenary talk about planetary protection. This is a big deal in the astrobiology community, the concern that sending probes to potentially habitable worlds such as Europa and Enceladus could contaminate them with Earth life. It’s also a harder problem to solve than it sounds like, partly because advanced electronics of the sort that are likely to run a probe don’t get along well with the things we typically use to sterilize equipment: bleach, extreme heat, radiation, and the like. The talk used a real-time interactive system, allowing the speaker to ask a question and display the results on the screen in real time. Multiple choice questions displayed as bar graphs, fill-in-the-blanks as word clouds, both changing from second to second as new answers came in.

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J. S. Huxley part 2: Volvox

Last time, I wrote about Julian Huxley’s 1912 book, The Individual in the Animal Kingdom, and his use of the volvocine algae as an example. I liked most of what he had to say, though I took issue with his assertion that

…all the other members of the family except Volvox…are colonies and nothing more—their members have united together because of certain benefits resulting from mere aggregation, but are not in any way interdependent, so that the wholes are scarcely more than the sum of their parts.

This is, of course, a matter of how we define a multicellular organism, but I think any definition that excludes, for example, Eudorina, is not a very useful one.

This time, I’ll look at the rest of what Huxley had to say about the volvocine algae, most of which is about Volvox:

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J. S. Huxley part 1: Gonium

Julian Huxley was one of the biologists responsible for the merging of Mendelian genetics and Darwinian evolution in the early 20th century, the modern synthesis. His most influential work was Evolution: The Modern Synthesis, published in 1942. Thirty years earlier, though, he published a book on biological individuality, The Individual in the Animal Kingdom. Thankfully, the copyright on this book has expired, so it is now part of the public domain, and a scanned version is available for free in pdf and epub versions from Google.

Huxley Cover

Any book with Volvox on the cover can’t be all bad!

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AbSciCon registration is open

abscicon2017_mesa.jpg__1240x600_q85_subsampling-2

Registration for the 2017 Astrobiology Science Conference is now open. The meeting will be in Mesa, Arizona April 24–28. You can save 50 bucks by registering before March 28th: $395 for students and $550 for everyone else. That’s a bit pricier than in the past, but there are travel grants available for students (the deadline for those has passed, though).

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What kind of individual do you mean?

One of the discussions I find most interesting in the philosophy of science is about what exactly constitutes a biological individual (or organism). The discussion would be a lot less interesting if everything were a vertebrate. Vertebrates (nearly always) develop from a single fertilized egg, so the (mostly) genetically homogeneous and (usually) genetically unique unit is the same as the spatially bounded, contiguous and physiologically integrated unit (this doesn’t even cover all the proposed criteria; see Clarke 2010 for a fairly comprehensive list with citations). But when we look outside of the vertebrates, what we often find is that some biological units have some of these properties and either groups or parts of those units have others.

Aphid on dandelion by Amoceann. Public domain image from Wikimedia Commons.

Aphid on dandelion by Amoceann. Public domain image from Wikimedia Commons.

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Volvox the art gallery

Volvox Art Gallery. Image from http://www.volvox-stnk.net/.Volvox Art Gallery. Image from www.volvox-stnk.net/.

If you’ve ever seen Volvox alive under a microscope, you probably remember it. They are beautiful, huge (relative to most things in a drop of pond water), and seemingly purposeful as they roll across the field of view. Volvox and its relatives have also played important roles in some big scientific and philosophical discussions, such as the evolution of multicellularity, the evolution of cooperation, and the nature of biological individuality. Given all that, it’s probably not too surprising that the volvocine algae, and Volvox in particular, have inspired a lot of art, including paintings,

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Graduate student position in the Nedelcu lab

If you’re a fan of Volvox and the volvocine algae and have recently received an undergraduate degree in biology or a related field, now’s your chance to get serious about studying them. Aurora Nedelcu is looking for a graduate student to join her lab at the University of New Brunswick. Professor Nedelcu is a major player in the Volvox community, having published foundational papers on diverse aspects of volvocine biology and organized the first two international Volvox meetings. This is a great opportunity to join a vibrant and growing research community:

A graduate student position is available in the laboratory of Aurora Nedelcu, in the Department of Biology at the University of New Brunswick, Fredericton, CANADA. Research in our laboratory is directed towards understanding general, fundamental issues in evolution – such as the evolution of multicellularity, development, cell differentiation, sex, programmed cell death, altruism.  Our research is rooted in the framework of transitions in individuality and evolution of complexity (at a conceptual level), and of cellular responses to stress (at a more mechanistic level).  The experimental model-system we are currently using is the green algal group, Volvocales (see our Volvocales Information Project; http://www.unbf.ca/vip). Highly motivated students with interests in either theoretical/genomics or experimental/molecular approaches, and previous research experience are encouraged to apply. Interested applicants should e-mail a CV, summary of research experience and interests, unofficial transcripts, and contact information for three referees to anedelcu@unb.ca.

Applicants should meet the minimum requirements for acceptance in the Biology Department Graduate Program (see http://www2.unb.ca/biology/Degree_Info/Graduate.html).

Relentless use of passive voice

Image from ragan.com.

Image from ragan.com.

I have had the phrase “relentless use of passive voice” in my head for years as a criticism of overly dry scientific writing. I thought I learned it from the excellent paper “How to write consistently boring scientific literature” by Kaj Sand-Jensen. Like Gould’s tennis stadium in “Muller Bros. Moving & Storage,” though, when I went back to look for it, it wasn’t where I thought it was. If anyone can tell me where the phrase actually originated, I would be grateful.

Wherever I first heard it, the phase has affected my scientific writing (or should I say ‘my scientific writing has been affected by the phrase’). I have the impression, supported by no hard data whatsoever, that the relentless use of passive voice has declined over the past few decades in scientific writing. It is now common to read about what “we” (the coauthors) did in the Methods and what “we” found in the Results. It’s not even that rare to see descriptions of what “I” did or found in a solo-authored paper (the horror!).

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