Performing the Office of Fins: Henry Baker on Volvox

Figure 27 from Baker 1764.

Figure 27 from Baker 1764.

Gilbert Smith’s foundational comparative study of the then known species of Volvox cites Henry Baker’s 1753 book, Employment for the Microscope : in Two Parts. Although he was writing 50+ years after Van Leeuwenhoek first described his “great round particles” (see “…of the bignefs of a great corn of fand…”), Baker makes no mention of this earlier publication. Since Part II of Employment is titled “An account of various animalcules, never before described, and of many other microscopical discoveries,” it seems that he was unaware of Van Leeuwenhoek’s work [emphasis mine]. Read a Philosophical Transactions for once in your life.*

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Volvox in Wired

Volvox photo by Jack Challoner

Volvox photo by Jack Challoner

Wired has a short blurb featuring some photos from Jack Challoner’s new book The Cell: A Visual Tour of the Building Block of Life, including the above Volvox picture. The caption is

Algae Colonies
Each green sphere is a colony of Volvox algae with more than 50,000 cells. Scientists study these glowing, freshwater organisms as models for how living creatures develop specialized cells and tissue. Strands of cytoplasm connect neighboring cells, allowing them to communicate, and slender flagella propel the colony through the water.

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New Volvox species

Hisayoshi Nozaki and colleagues have done it again: in a new PLoS One article, they have described yet another new species of Volvox, V. reticuliferus (see also “Volvox 2015: taxonomy, phylogeny, & ecology“):

Figure 1A from Nozaki et al. 2015: Surface view of asexual Volvox reticuliferus spheroids.

Figure 1A from Nozaki et al. 2015: Surface view of asexual Volvox reticuliferus spheroids.

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Volvox ovalis

Volvox ovalis

Volvox ovalis, strain NIES-2569.Creative Commons License
Volvox ovalis by Matthew Herron is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

Volvox ovalis was described by Hisayoshi Nozaki and Annette Coleman in 2011 from a strain collected near College Station, Texas. Colonies are often distinctly egg-shaped, up to 450 µm long, with 1000-2000 somatic cells and 8-12 gonidia. A member of the section Merrillosphaera, it is closely related to V. tertius and V. spermatosphaera:

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Hexadecaflagellates!

Kirsty Wan and Ray Goldstein have posted a new paper to arXiv*: “Coordinated Beating of Algal Flagella is Mediated by Basal Coupling.” The paper examines in unprecedented detail the mechanics of intracellular flagellar coordination. That’s cool and all, but first: hexadecaflagellates!

Wan & Goldstein compared algal cells with 2, 4, 8, and, yes, 16 flagella. I never knew there was such a thing. Pyramimonas cyrtoptera has 16, and its relative P. octopus has…well, you can probably guess.

Fig. 7 from Wan and Goldstein 2015: Pyramimonas cyrtoptera.

Fig. 7 from Wan & Goldstein 2015: Pyramimonas cyrtoptera, with hella flagella.

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Why don’t we revise volvocine taxonomy?

Volvocine taxonomy is in a sorry state. Most nominal genera, and some nominal species, are almost certainly polyphyletic. More than once, I’ve been asked during a talk, “Why is Volvox scattered all over the tree?”

JPhycol2010Fig2a

Fig. 2A from Herron et al. 2010. The traits characteristic of the genus Volvox—asexual forms with >500 cells, only a few of which are reproductive, and oogamy in sexual reproduction—have arisen at least three times independently: once in the section Volvox (represented by V. globator, V. barberi, and V. rousseletii), once in V. gigas, and once or possibly twice in the remaining Volvox species. Branch shading indicates maximum-parsimony reconstruction (white = absent, black = present, dashed = ambiguous). Pie charts indicate Bayesian posterior probabilities at selected nodes. Numbers to the left of cladograms indicate log-Bayes factors at selected nodes: positive = support for trait presence, negative = support for trait absence. Interpretation of log-Bayes factors is based on Kass and Raftery’s (1995) modification of Jeffreys (1961, Theory of probability. 3rd edn. Oxford Univ. Press, Oxford, UK.): 0 to 2, barely worth mentioning; 2 to 6, positive; 6 to 10, strong; >10, very strong. Boldface numbers following species names indicate Volvox developmental programs following Desnitski (1995).

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Who are you calling lower?

Weismann Fig. 62

Fig. 62 from Weismann, A. 1904. The Evolution Theory. London: Edward Arnold. Pandorina morum; after Pringsheim. I, A young colony, consisting of 16 cells. II, Another colony, whose cells have reproduced daughter-colonies; all the cells uniformly alike. III, A young Volvox-colony; sz, somatic cells; kz, germ-cells.

I needed to cite some information from August Weismann’s 1904 book The Evolution Theory1 yesterday, so I did something I rarely do anymore: walked over to the library and checked out a physical copy. The University of Montana library has a first edition, two-volume set of the translation by Arthur Thomson. I’m always interested to see how biologists thought about Volvox before people like Richard Starr, David Kirk, and Rüdiger Schmitt came on the scene. All of the quoted text is from pages 257-261 in Volume I.
Among the lower Algae there is a family, the Volvocinæ, in which the differentiation of the many-celled body on the principle of division of labour has just set in; in some genera it has been actually effected, though in the simplest way imaginable, and in others it has not yet begun.

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