Wildfire effects on genetic diversity and recolonization of Longfin Dace, Agosia chrysogaster
Authors: Tyler Pilger, Keith Gido, David Propst, James Whitney, Thomas Turner
Year: 2015 (xlvii)
Abstract
Wildfires are important disturbance events for cold and warm-water stream biota of southwestern North America. Whereas wildfire effects on abundance and community composition are relatively well-documented, effects on genetic diversity and structure are not. From 2011 to 2013, the upper Gila River basin experienced a series of wildfires with associated ash flows that led to local extirpations of native and nonnative fishes. One species, longfin dace, Agosia chrysogaster, is an abundant and widespread native that exhibits a "boom-bust" ecology and a rapid colonizer, making it an ideal candidate for evaluating wildfire effects on fishes. We used genetic data collected pre-wildfire (2010), immediately following the Whitewater-Baldy Fire (2012), and 2 years post Whitewater-Baldy (2014) to evaluate changes in genetic diversity and genetic structure that resulted from extirpation/recolonization dynamics. Genetic diversity (heterozygosity and allelic richness) decreased slightly rangewide in 2012 and 2014 compared to 2010, whereas genetic differentiation (FST) increased in 2012 but 2014 values were similar to pre-fire values. Genetic effective size (Ne) decreased in 2012 but returned to pre-fire levels in 2014. Longfin dace appeared to exhibit genetic resilience to the wildfires that is likely due to recolonization from refuge sites. Disentangling the roles of dispersal and local compensatory reproduction for genetic resilience is a necessary step for managing biodiversity following large wildfires.