Trade-offs among life history traits and parasite intensity in the White Sands pupfish (Cyprinodon tularosa)

Authors: Justin Waraniak, David Rogowski, Craig Stockwell

Year: 2021

Abstract

The White Sands pupfish (Cyprinodon tularosa) is a threatened species historically found in four desert spring and stream systems in the Tularosa Basin, New Mexico, USA. Of these, the Salt Creek and Malpais Spring populations are native whereas the Lost River and Mound Spring populations were established in the 1970’s and are descended from the Salt Creek population. Previous work has shown evidence for local adaptation associated with high inter-system variation in flow, salinity, and trematode parasite densities. This study was designed to characterize life history traits within each of these systems to determine whether differences in environmental conditions and parasites have caused differentiation of life history strategies among C. tularosa populations. A total of 768 females were collected from the four populations during the summers of 2000 and 2001. Scale-based age estimates, body size, body composition (dry weight, lipid content), reproductive tissue mass, and parasite loads were measured for each fish. Multivariate analyses of life history traits showed high variation within systems, but little variation that could effectively discriminate among systems. These results suggest that environmental differences have not led to noticeable differentiation in life history traits among the populations of the White Sands pupfish. This contrasts with the differences in body shape observed in these same systems in previous studies. There was no clear evidence for a direct trade-off between parasite intensity and reproductive effort, but rather, this trade-off appears to be mediated by fat stores and body size. Parasite infections and reproductive investments resulted in reductions of fat stores and the consequences of parasite infections were more severe for smaller fish.