The conservation genetics of Ash Meadows pupfish populations. I. The Warm Springs pupfish Cyprinodon nevadensis pectoralis

Abstract

The Warm Springs pupfish (Cyprinodon nevadensis pectoralis) inhabits several low flow (\0.15 cfs) springs in an otherwise dry Mojave Desert landscape. Increasing demands on groundwater coupled with predictions of decreased precipitation from global warming make this species a sentinel for biodiversity dependent on springs.Here we examine mitochondrial DNA haplotypes and nuclear microsatellite genotypes for individuals sampled in 1998 and 2007 as a means of inferring the historical demography of the subspecies. Estimates of genetic effective population size from comparison of allele frequencies over time underscores that all spring populations support small populations, typically \100 individuals. Such small population sizes suggest spring populations may have heightened probabilities of extirpation. Despite small population sizes, all springs harbor relatively high levels of genetic variation for both nuclear and mitochondrial DNA. Unexpectedly high levels of variation may be explained by recent declines in population size coupled with rare episodes of gene flow between springs suspected of occurring during flooding events. The inferences gained from the genetic data provide the basis for evaluating current and future restoration plans. The genetic data suggest there is a need to balance the predicted positive effects of restoring hydrological connectivity with the potential negative impacts of providing avenues for the spread of exotic species detrimental to pupfish populations.

Going, going, gone? Loss of genetic diversity in two critically endangered Australian freshwater fishes, Scaturiginichthys vermeilipinnis and Chlamydogobius squamigenus, from Great Artesian Basin springs at Edgbaston, Queensland, Australia

“…In contrast, one temporal study of the artesian spring snail, Fonscochlea accepta , before and after catastrophic flooding, showed that such natural events may help boost effective population sizes and allelic richness in otherwise fragmented populations (Worthington‐Wilmer et al , ). Unfortunately, the benefits of promoting gene flow among populations via flooding must be balanced with the costs of allowing the spread of invasive species, as is the case with red‐finned blue‐eye and also Warm Springs pupfish, Cyprinodon nevadensis pectoralis (Martin, ). For red‐finned blue‐eye, a fish that is perilously close to extinction, active management of naturally‐occurring and relocated populations should be continually informed by population genetics in order to maximize the survival prospects for the species.…”

“…Artesian springs are isolated habitats, intermittently connected by flooding, high rainfall and overland flow. For most of the time, spring communities evolve in isolation, and as such, high levels of genetic structure are often observed in spring biota (for example, Warm Springs pupfish; Martin, ). Using AMOVA, this study detected significant genetic structure among red‐finned blue‐eye populations, which increased in magnitude between the 1990s and 2010 sampling events.…”

“…There is overwhelming evidence demonstrating that populations of endangered species in isolated and specific habitats are at increased extinction risk (Martin, ; Fensham et al , ). Although arresting the decline of extant endangered species is a worthy goal, it is difficult, and especially so once population sizes become very low or when resources are limited (Hammer et al ., ).…”

Dramatic shifts in the gene pool of a managed population of an endangered species may be exacerbated by high genetic load

“…Cyprinodon n. pectoralis is restricted to a set of five lowflow springs and is genetically divergent from C. n. mionectes (Martin 2010). Cyprinodon n. mionectes is the most widespread and abundant pupfish in AMNWR (Soltz and Naiman 1978).…”