Population genetics of the endemic Large-crested toad (Incilius cristatus): a declining and critically endangered species

Abstract

Abstract The Large-crested toad is an endemic species of the mountain cloud forests of the Sierra Madre Oriental in Mexico. It is listed as endangered, and the population trend is decreasing. We used mitochondrial fragments 12S (450 bp) and cytochrome b (410 bp) from four toads’ populations from remnant fragments of mountain cloud forest in Puebla and Veracruz to estimate the genetic’ structure, gene flow, and demographic history. The 12S gene had a single haplotype and null nucleotide diversity. The cytochrome b fragment showed 4 haplotypes, intermediate nucleotide diversity (), and strong genetic structuring (). Demographic history suggests that there is a low effective population size (), possibly due to post-bottleneck expansion and contraction events in some populations. Current difficulty finding individuals at localities where they had been previously documented suggests that the population continues to decline, resulting in low diversity and gene flow. Habitat fragmentation and loss, as well as water pollution at breeding sites, increases the probability of extinction of this species. The importance of establishing conservation strategies for the habitat and genetic diversity of the remaining populations is highlighted.