Using genetics to characterize native fish response to disturbance: a case study from the Upper Gila River basin

Authors: Tyler J Pilger, Keith B Gido, David L Propst, James E Whitney, Thomas F Turner

Year: 2016 (xlviii)

Abstract

Wildfires are important disturbance events for terrestrial and aquatic ecosystems throughout the Western U.S. Wildfire related ash and debris flows can strongly influence fish communities yet there is little empirical data on their influence on genetic diversity and spatial structuring. Population genetic monitoring beginning in 2010 was used to characterize genetic summary statistics for six native fish species and evaluate genetic responses to ash/debris laden floods resulting from a series of three catastroph ic wildfires (2011, 2012, and 2013) in the Upper Gila Basin of New Mexico. Three species exhibited declines in diversity (heterozygosity and/or allelic richness) and decreased numbers of breeders (linkage disequilibrium effective size) over the c ourse of the study, whereas other species were more resistant to loss of diversity. Species also exhibited substantial changes in allele frequencies over time indicated by low variance effective size estimates. In conjunction with temporal changes in genetic str ucture (FST), these data suggest substantial demographic changes occurred for several species. By comparing temporal changes in genetic diversity and structure spanning pre-disturbance through recovery phases, we developed a conceptual framework that makes explicit predictions concerning the trajectory of genetic summary statistics. Applying our framework across species revealed differences in relative roles of dispersal and local compensatory reproduction to resilience and recovery following large disturbances.