Biogeography of Selected Spring Endemics in Texas Interglacial-Drought Refugia with Unexpected Insights from a Spring-Dependent Nematode Parasite

The contemporary distribution of crenobiontic endemics in central Texas is enigmatic because only some springs are occupied by crenobionts despite other unoccupied having seemingly suitable habitats. In the absence complete paleo-records, a cohesive and widely accepted explanation for this biogeography has eluded researchers many years. We suggest that data on species with obligate coevolution, such as parasites multiple hosts their life cycles, can help to fill intervening gaps paleo-record parasite indicates its cohabitated without interruption since arrival parasite. To test conjecture, we studied one endemic select few springs, Huffmanela huffmani. By studying intermediate host, geologic paleo-climatic records, performing lab experiments live animals, examining archived museum specimens definitive from 1950s, were able predictions about how H. huffmani became what it today. Our results corroborate narrative suggesting several severe droughts Wisconsin glaciations responsible sculpted present-day crenobionts.