Comparative population genetics of two congeneric duck schistosomes, Trichobilharzia querquedulae and T. physellae.

EBBS E; BRANT S. V.; FLORES V.; LOKER E. S.

San Antonio

Congreso; 92th Annual Meeting of the American Society of Parasitologists; 2017

Sociedad Parasitológica Americana

Host-parasite systems exist across complex and ecologically heterogeneous landscapes; they evolve at thepopulation level and are shaped by many co-occurring factors (immunology, evolutionary constraints,ecology). Host ecology (dispersal, distribution, life history) is thought to be important in shaping parasitemicroevolution, however identifying relevant ecological factors is challenging as it is unknown to whatextent evolutionary history has determined contemporary microevolutionary patterns. In an effort tocontrol for this, we assessed the population genetics of two congeneric trematodes (T. querquedulae and T.physellae), which are assumed to have evolved under similar evolutionary constraints. These wormsinfect ducks and freshwater snails, both T. querquedulae and T. physellae infect Physa spp. snails, whichare common snails throughout North America and one species (Physa acuta) is globally invasive. Theseworms are associated with different duck groups in distinct lineages and with different habitatpreferences and distribution. Trichobilharzia querquedulae is found globally while T. physellae isrestricted to North America. In comparing T. querquedulae (n=100) and T. physellae (n=60) from 20different localities we see strong discordance of population genetic patterns and intraspecific variation,based on CO1 & ND4 genetic markers. Trichobilharzia querquedulae maintains greater genetic diversityand effective population sizes than T. physellae. Within host diversity of T. querquedulae is equal tobetween host diversity, suggesting a well-mixed and genetically diverse metapopulation. Geographicstructuring within T. physellae is minimal and genetic diversity is low, relative to T. querquedulae. Thesedata represent populations? sampled across the range of two widely distributed congeneric trematodesand reveal strikingly different microevolutionary stories, suggesting the importance of evolutionary andecological forces in shaping their contemporary populations and consequently the evolutionary potentialof Trichobilharzia populations.