Temporal genetic and demographic monitoring of pond-breeding amphibians in three contrasting population systems

Abstract

Quantifying the relationship between demographic patterns and genetic diversity are important in predicting temporal population genetic changes. To make predictions there must be an understanding of the relationship between census size, the effective number of breeders (N b ) and effective population size (N e ). We evaluate the temporal genetic variation between three populations of Ambystoma salamanders, and compare genetic and demographic estimates of N b and N e . We sampled two wetlands, RB and GB for A. opacum and sampled A. talpoideum at RB, over a 20-year period. Ambystoma opacum colonized the RB wetland in 1980 and the population has steadily expanded as A. talpoideum has declined towards local extinction; the GB population of A. opacum has remained relatively large and stable over this same time period. Genetic variation at 10 microsatellites remained stable at each population over the sampled time frame, and did not reflect changes in population size. Genetic estimates of N b also did not reflect demographic trends, and were lower than demographic estimates of N b . Genetic methods of determining N e gave similar estimates to demographic methods. Our findings indicate that sample sizes and number of markers typically used in genetic studies do not provide enough precision to monitor population size changes in amphibians, which likely violate many of the assumptions of N b and N e estimation models. These findings should be considered when using N e in conservation and management assessments of amphibian populations.

Highly Connected Populations and Temporal Stability in Allelic Frequencies of a Harvested Crab from the Southern Pacific Coast

“…Similar results also have been described for the frog Bufo calamita [83], the sturgeon Acipenser fulvescens [84] and the salamanders Ambystoma opacum and A . talpoideum [85]. …”

Amphibian molecular ecology and how it has informed conservation

“…Continued 10 microsats Inbreeding correlated with lower survival in the wild, but not the 2013), and many of these studies would benefit from paired field-based censuses to better understand the relationship between N e and census size. However, care must also be taken in the interpretation of molecular population size estimation, particularly when using small numbers of markers or individuals to estimate large populations (Nunziata et al 2015). While it is clear that no two amphibian systems are identical, several conservation-relevant conclusions have emerged in the amphibian literature.…”

Understanding variation in salamander ionomes: A nutrient balance approach

“…Site was a poor predictor of stoichiometric variation in males and metamorphs despite strong differences in genetic structure for A. opacum between these populations (Nunziata et al, 2015). Site was a poor predictor of stoichiometric variation in males and metamorphs despite strong differences in genetic structure for A. opacum between these populations (Nunziata et al, 2015).…”

“…Both species appear to have relatively similar larval growth rates (Scott, 1990;Semlitsch, 1987), although A. talpoideum typically metamorphoses later and at a larger body size than A. opacum (Pechmann, 1995). Consequently, both species had stable populations at GB over our study period (Nunziata et al, 2015), but A. opacum populations increased and A. talpoideum decreased apparently due to a shortened hydroperiod at RB (Daszak et al, 2005). the production of juveniles that metamorphose and emigrate from wetlands) of both species is tied to hydroperiod, but A. talpoideum requires a later date of pond drying and more frequently faces inadequate water at RB, which can result in catastrophic larval mortality (Daszak et al, 2005).…”