Genetic rescue of an inbred captive population of the critically endangered Puerto Rican crested toad (Peltophryne lemur) by mixing lineages

Abstract

The Puerto Rican crested toad (Peltophryne lemur) is currently composed of a single wild population on the south coast of Puerto Rico and two captive populations founded by animals from the northern and southern coasts. The main factors contributing to its decline are habitat loss, inundation of breeding ponds during storms, and impacts of invasive species. Recovery efforts have been extensive, involving captive breeding and reintroductions, habitat restoration, construction of breeding ponds, and public education. To guide future conservation efforts, genetic variation and differentiation were assessed for the two captive colonies and the remaining wild population using the mitochondrial control region and six novel microsatellite loci. Only two moderately divergent mitochondrial haplotypes were found, with one fixed in each of the southern and northern lineages. Moderate genetic variation exists for microsatellite loci in all three groups. The captive southern population has not diverged substantially from the wild population at microsatellite loci (F ST = 0.03), whereas there is little allelic overlap between the northern and southern lineages at five of six loci (F ST [ 0.3). Despite this differentiation, they are no more divergent than many populations of other amphibian species. As the northern breeding colony may not remain viable due to its small size and inbred nature, it is recommended that a third breeding colony be established in which northern and southern individuals are combined. This will preserve any northern adaptive traits that may exist, and provide animals for release in the event that the pure northern lineage becomes extirpated.

Ex situ conservation genetics: a review of molecular studies on the genetic consequences of captive breeding programmes for endangered animal species

“…Studies on small mammals, marsupials and fish species were scarce (2, 6 and 2%, respectively). There were only two studies on endangered amphibian species (Kraaijeveld-Smit et al 2006;Beauclerc et al 2010) and none at all on endangered invertebrates. These results mirror the well-known bias towards charismatic vertebrates in conservation, research and publication policy (Artacho 2006;Maslin 2006;Gippoliti and Amori 2007).…”

Global Amphibian Declines, Loss of Genetic Diversity and Fitness: A Review

“…It is tempting to propose the relatively simple solution of establishing links between isolated breeding assemblages to counteract the negative effects of genetic drift. For example, a management strategy involving artificial mixing of lineages was successfully utilised to address inbreeding in captive populations of the Puerto Rican crested toad Peltophyrne lemur [150]. However, caution must be exercised before considering such artificial gene flow [151].…”

Conserving small and fragmented populations of large mammals: Non-invasive genetic sampling in an isolated population of Asian elephants in Nepal

“…Such a mating system will produce a pattern of heterozygosity excess. More important is the evidence for male immigration and its potential to counteract genetic erosion, which in turn reduces the risk of inbreeding depression (Beauclerc et al 2010;Bijlsma et al 2010;Couvet 2002;Ingvarsson 2001;Keller & Waller 2002;Schwartz & Mills 2005). Since the re-establishment in 1994, the population has been increasing due to local recruitment, as also evident from the large proportion of young animals (70% calves, juveniles and sub-adults).…”