Search USGS⌕ Search
Home/Archive/USGS

USGS · 70194289

Effective population size and genetic structure of a Piute ground squirrel (Spermophilus mollis) population

Michael F. Antolin·Beatrice Van Horne·Michael D. Berger
View original source ↗Export metadata ↓

Abstract

Piute ground squirrels ( Spermophilus mollis ) are distributed continuously in habitat dominated by native shrubs and perennial grasses in the Snake River Birds of Prey National Conservation Area in Idaho, U.S.A. This habitat is being fragmented and replaced by exotic annual plants, changing it to a wildfire-dominated system that provides poor habitat for ground squirrels. To assess potential effects of this fragmentation on ground squirrel populations, we combined an estimate of effective population size ( N e ) based upon a demographic study with a population genetic analysis. The study area included three subpopulations separated from each other by 8–13 km. The ratio of effective population size to census number ( N e / N ) was 0.57. Combining N e / N with dispersal distances from a radio-tracking study, we calculated that neighborhood size was 62.2 ha, which included between 204 and 480 individuals. Our population genetic analysis (based on randomly amplified polymorphic DNA (RAPD) and microsatellite markers) showed relatively low levels of genetic differentiation (Q populations 0.07–0.10) between subpopulations and no inbreeding within subpopulations ( f = 0.0003). These estimates of population subdivision translate into an effective migration rate ( N e m ) of 2.3–3.3 per year, which represents a high level of gene flow. Invasion by exotics will reduce the overall productivity of the habitat, and will lead to isolation among subpopulations if favorable habitat patches become isolated.

Explore related subjects

Canadian Journal of ZoologyArticle

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Michael F. Antolin, Beatrice Van Horne, Michael D. Berger. 2001. Effective population size and genetic structure of a Piute ground squirrel (Spermophilus mollis) population. https://doi.org/10.1139/z00-170

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related USGS reports

USGS2025

Harmless tags or hazardous ads? Investigating the potential for ear tags to increase predation on neonatal ungulates

Studies involving individually marked animals provide insights predicated on the assumption marked individuals are accurate models of their unmarked counterparts. Taxa-specific and marker-specific examinations are needed to determine if marked animals are suitable models for the parameter(s) being measured. Our objective was to determine if brightly colored ear tags influenced the probability of predation for neonatal ungulates. We captured 94 neonatal pronghorn (Antilocapra americana (Ord, 1815)), fitted each neonate with a tracking collar, and attached a yellow ear tag to 49 (52.1%) of the captured neonates. We monitored the survival of each neonate during 2023–2024 in Oklahoma, USA. Predation was the leading cause of mortality during our monitoring period and accounted for 29 (82.9%) of the 35 mortalities with a known cause. Coyotes (Canis latrans Say, 1823) were the predominant predator of neonatal pronghorn in our study area. Presence of a yellow ear tag seemingly did not influence the probability of predation, even though coyotes can distinguish yellow objects from most natural backgrounds. A larger sample size may be needed to validate our results, but neonatal ungulates with an ear tag appear to be accurate models of neonatal ungulates without an ear tag when examining predation risk.

Oklahoma↗
USGS2025

Fine-scale farming features drive resource selection of a small carnivore of conservation concern

Anthropogenic factors are accelerating species extinction, with small mammalian carnivores among the most affected. These species play vital ecological roles, yet their conservation needs are often overlooked. Our study focused on the plains spotted skunk ( Spilogale interrupta (Rafinesque, 1820)), a small carnivore that has experienced population declines. We hypothesized that their resource selection was influenced by factors expected to influence prey availability, protection from predators, and human activity. We tracked 14 plains spotted skunks in east-central South Dakota, USA, over 2 years during spring and summer. Using mixed-effects logistic regression, we identified seasonal habitat associations. In spring, plains spotted skunks selected areas near farming structures and human development, avoiding high wetland density and crop cover. In summer, they continued to select areas near farming structures and low human development, but also high wetland density and pasture, while avoiding hay bales and crop cover. Our first analysis of the species’ resource use in the Great Plains indicates that plains spotted skunks select habitats with permanent small-scale agricultural features and varying levels of human development across seasons. Our findings suggest that species’ persistence in the region may depend on conservation strategies that account for seasonal planning, habitat heterogeneity, and key agricultural structures.

Canadian Journal of Zoology↗
USGS2024

Using the electron transport system as an indicator of organismal thermal tolerance and respiratory exploitation

Freshwater ecosystems are undergoing rapid thermal shifts, making it increasingly important to understand species-specific responses to these changes. Traditional techniques for determining a species’ thermal tolerance are often lethal and time consuming. Using the enzyme activity associated with the electron transport system (ETS; hereafter referred to as enzyme assay) may provide a non-lethal, rapid, and efficient alternative to traditional techniques for some species. We used largemouth bass Micropterus salmoides (Lacepede, 1802) to test the efficacy of using an enzyme assay to determine thermal tolerance and respiratory exploitation in response to variable acclimation temperatures. Three tissue types were dissected from fish acclimated to 20, 25, or 30 °C and used in ETS assays at temperatures ranging from 7.5 to 40 °C. While there were significant differences among tissue types and acclimation temperatures, maximal enzyme activity occurred from 25.23 to 31.91 °C. Fish lost equilibrium at 39–42 °C in traditional CT max trials, significantly higher than the upper optimum range determined via enzyme assays. The ratio of enzyme activity to measured whole organism respiration rate decreased with increasing water temperature, with the largest changes occurring at the upper optimum thermal range determined by enzyme assays. Our results indicate that ETS analysis may prove useful for obtaining biologically relevant thermal tolerances.

Canadian Journal of Zoology↗