Ripon College, Biology, Ripon, WI 54971
A critical question in population biology is whether speciation is taking place in isolated populations. To examine this problem we investigated the phenology of zooplankton resting egg hatchlings from dry sediment of ephemeral pools in Big Bend National Park. To do this we re-hydrated sediments from seven dry pools and incubated a replicate of each sample at 12˚C and 25˚C. We observed significant hatching among the latter samples, which was generally manifested in spates of one species after another: first a surge of the predator, Asplanchna brightwellii, then a greater quantity of an herbivore, Epiphanes brachionus. Rotifers were preserved in 70% alcohol and sent to our colleagues at the University of Texas El Paso, where molecular analysis will be employed to determine the variation in genetic signatures among species hatched in the sites we examined and other across the Chihuahuan Desert.
[Abstract (DOC)]