EEB graduate student Jingchun Li has been awarded a National Geographic Society Young Explorers Grant from the NGS Committee for Research and Exploration.
The $5,000 award will support a field trip to southern Australia where Li and her collaborators, Dr. Lisa Kirkendale and Dr. Peter Middelfart from the Western Australian Museum, plan to conduct 30 days of extensive field sampling of a superfamily of clams, Galeommatoidea, in the Flindersian biogeographic province (southwest Australia).
This phase of Li’s clam study will test the relative importance of free-living and commensal lifestyles in driving regional galeommatoidean diversification. Using data from the Australian species, the researchers will reconstruct the phylogeographic history of the regional taxa.
Li’s research represents a first attempt to evaluate biotic vs. abiotic diversification mechanisms in an extant diverse marine lineage. The title of her project is "The role of biotic association in marine diversification processes: a regional test." Li works in the lab of her advisor, Professor Diarmaid Ó Foighil.
The marine bivalve superfamily Galeommatoidea is an apt group for addressing the topic for two reasons. First, Galeommatoidea is a megadiverse group that has arguably the highest level of species diversity among marine bivalve superfamilies. Secondly, the clams embody a clear ecological dichotomy in that many members are free-living crevice dwellers while many others have intimate commensal relationships with diverse invertebrate hosts (attached to, or living in burrows of hosts).
The researchers hypothesize that commensal species are subject to host-mediated diversification mechanisms (e.g. host shifting), in addition to geographic isolation mechanisms (e.g. vicariance) that also act on free-living taxa. And this additional diversification opportunity may contribute to the high species diversity of Galeommatoidea.
“By comparing diversification rates/patterns between commensal and free-living lineages for the entire superfamily, the effect of biotic association can be assessed,” Li explained. “However, this approach is unlikely to yield a fine grained comparison of microevolutionary processes between the two groups. To do this, I need to study taxa of both groups that have diversified across a shared biogeographic canvas, so their evolutionary histories are comparable. The temperate coast of southern Australia represents an ideal study system because of its high degree of endemism and presence of three long recognized biogeographic provinces along a contiguous coastline.”