The lead author of the recent Evolution paper has posted a commentary on kudos that includes some ideas not included in the paper:
The life cycle and ecology of volvocine algae may be key to understanding the long-term persistence of self-fertilization. First, selfing in homothallic volvocine algae is facultative; in a genetically diverse population, most matings will be between genetically distinct strains. Second, volvocine algae have a haploid-dominant life cycle with a metabolically active, multicellular haploid stage and a dormant, unicellular diploid stage. Inbreeding depression may thus be less important than in species with diploid-dominant life cycles. Finally, the dormant diploid stage allows volvocine algae to overwinter, meaning that the ability to self-fertilize is crucial for the survival of colonists to new ponds. Thus facultative selfing might provide volvocine algae with the benefits of outcrossing (when other genotypes are around) without the cost of potentially being unable to find a mate.
Graduate student Jacob Boswell got the word yesterday that his Society of Systematic Biologists Graduate Student Research Award will be funded. The award will support his sequencing of cDNA from various volvocine species for multi-gene phylogenetic reconstructions.
Figures 1-9 from Nozaki et al. 2017. Pleodorina sphaerica.
Pleodorina sphaerica Iyengar was considered to be a phylogenetic link between Volvox and the type species Pleodorina californica Shaw because it has small somatic cells distributed from the anterior to posterior poles in 64- or 128-celled vegetative colonies. However, cultural studies and molecular and ultrastructural data are lacking in P. sphaerica, and this species has not been recorded since 1951. Here, we performed light and electron microscopy and molecular phylogeny of P. sphaerica based on newly established culture strains originating from Thailand. Morphological features of the present Thai species agreed well with those of the previous studies of the Indian material of P. sphaerica and with those of the current concept of the advanced members of the Volvocaceae. The present P. sphaerica strains exhibited homothallic sexuality; male and facultative female colonies developed within a single clonal culture. Chloroplast multigene phylogeny demonstrated that P. sphaerica was sister to two other species of Pleodorina (P. californica and Pleodorina japonica Nozaki) without posterior somatic cells, and these three species of Pleodorina formed a robust clade, which was positioned distally in the large monophyletic group including nine taxa of Volvox sect. Merrillosphaera and Volvox (sect. Janetosphaera) aureus Ehrenberg. Based on the present phylogenetic results, evolutionary losses of posterior somatic cells might have occurred in the ancestor of P. californica and P. japonica. Thus, P. sphaerica might represent an ancestral morphology of Pleodorina, rather than of Volvox.
Nozaki, H., W. Mahakham, S. Athibai, K. Yamamoto, M. Takusagawa, O. Misumi, M. D. Herron, F. Rosenzweig, M. Kawachi. 2017. Rediscovery of the species of “ancestral Volvox”: morphology and phylogenetic position of Pleodorina sphaerica (Volvocales, Chlorophyceae) from Thailand. Phycologia 56:469–475. doi: 10.2216/17-3.1
Teacher interns Ellen Parchen and R. L. Boyles will be heading to Los Angeles for the National Science Teachers Association National Conference on Science Education March 30-April 2. They’ll be presenting high school curricula for hands-on experimental evolution developed in collaboration with Vaughn Cooper. Ellen and R.L. worked in the lab over the last two summers learning lab techniques and developing curriculum as part of the Broader Impacts for the NSF grant.