Alexey Desnitskiy, Stuart Sym, and Pierre Durand have published a new paper in Transactions of the Royal Society of South Africa recounting the contributions of South African phycologist Mary Agard Pocock to Volvox research [full disclosure: Pierre Durand and I were labmates in Rick Michod’s lab at the University of Arizona for a time, and Alexey Desnitskiy is a friend and collaborator].

Pocock, who defended her Ph.D. in 1932, made careful observations of both sexual and asexual development in several species of Volvox that she collected in southern Africa: V. africanus, V. capensis,V. rousseletii, and V. gigas (which she originally described). For some of these species, hers are still the only detailed descriptions of their ontogeny:

Pocock studied almost all aspects of asexual and sexual development in several African Volvox species, with the exception of sexual differentiation control…Pocock’s data on embryonic inversion in V. africanus, V. capensis, V. gigas and V. rousseletii retain their importance today. Her description of inversion during asexual development in V. africanus and V. capensis remains the only detailed study of this process in these two species and her observations of embryonic inversion in V. gigas and V. rousseletii were corroborated almost 40 years later. [references omitted]

Figure 2L-O from Pocock 1933. Inversion in Volvox gigas.

Among many other contributions, Dr. Pocock described zygote germination in Volvox tertius and published, with Marion Cave, comparative studies of chromosome numbers in volvocine algae. As Desnitskiy and colleagues emphasize, many of her observations remain valuable for comparative studies.

Today Mary Agard Pocock is acknowledged for her contributions to the ontogenetic aspects of Volvox biology…her impact on Volvox research continues long after her death.

Fittingly, they conclude

…it is worth remembering that the eminent phycologist [Richard] Starr (1970b, p. 234) named a species of Volvox in Dr Pocock’s honour (Volvox pocockiae Starr) and emphasised that her “contributions to our knowledge of the genus are classic”.

Figures 1-3 from Starr 1970. Volvox pocockiae. Fig. 1. Asexual spheroid showing gonidia enlarging prior to division. x85. Fig. 2. Surface view of asexual spheroid with embryos. x 85. Fig. 3. Same spheroid as that in Fig. 2 but at lower focal level, showing cluster of sperm packets formed by dwarf male at posterior of spheroid. x85.

The article is paywalled, but Professor Desnitskiy has kindly allowed me to share a link that will allow a limited number of free downloads: https://www.tandfonline.com/eprint/QMUhNJAJ9WPTVbM5WUfU/full. Please use this only if you don’t have an institutional subscription to Transactions of the Royal Society of Africa; if you do have an institutional subscription, please use the DOI: http://doi.org/10.1080/0035919X.2018.1534761.

Stable links:

Desnitskiy, A. G., S. D. Sym, and P. M. Durand. 2018. On the contribution of Mary Agard Pocock to developmental biology research of the genus Volvox L. Trans. R. Soc. South Africa, online early. DOI: 10.1080/0035919X.2018.1534761

Pocock, M. A. 1933. Volvox and associated algae from Kimberley. Ann. South African Museum 16:473–522. No DOI, available at https://www.biodiversitylibrary.org/page/1489694#page/543/mode/1up

Starr, R. C. 1970. Volvox pocockiae, a new species with dwarf males. J. Phycol. 6:234–239. DOI: 10.1111/j.1529-8817.1970.tb02387.x