Idaho Ground Squirrel Research Articles

Development and validation of a GT-seq panel for genetic monitoring in a threatened species using minimally invasive sampling.

Minimally invasive samples are often the best option for collecting genetic material from species of conservation concern, but they perform poorly in many genomic sequencing methods due to their tendency to yield low DNA quality and quantity. Genotyping-in-thousands by sequencing (GT-seq) is a powerful amplicon sequencing method that can genotype large numbers of variable-quality samples at a standardized set of single nucleotide polymorphism (SNP) loci. Here, we develop, optimize, and validate a GT-seq panel for the federally threatened northern Idaho ground squirrel (Urocitellus brunneus) to provide a standardized approach for future genetic monitoring and assessment of recovery goals using minimally invasive samples. The optimized panel consists of 224 neutral and 81 putatively adaptive SNPs. DNA collected from buccal swabs from 2016 to 2020 had 73% genotyping success, while samples collected from hair from 2002 to 2006 had little to no DNA remaining and did not genotype successfully. We evaluated our GT-seq panel by measuring genotype discordance rates compared to RADseq and whole-genome sequencing. GT-seq and other sequencing methods had similar population diversity and F ST estimates, but GT-seq consistently called more heterozygotes than expected, resulting in negative F IS values at the population level. Genetic ancestry assignment was consistent when estimated with different sequencing methods and numbers of loci. Our GT-seq panel is an effective and efficient genotyping tool that will aid in the monitoring and recovery of this threatened species, and our results provide insights for applying GT-seq for minimally invasive DNA sampling techniques in other rare animals.

Hit Snooze: An Imperiled Hibernator Assesses Spring Snow Conditions to Decide Whether to Terminate Hibernation or Reenter Torpor.

AbstractMany animals follow annual cycles wherein physiology and behavior change seasonally. Hibernating mammals undergo one of the most drastic seasonal alterations of physiology and behavior, the timing of which can have significant fitness consequences. The environmental cues regulating these profound phenotypic changes will heavily influence whether hibernators acclimate and ultimately adapt to climate change. Hence, identifying the cues and proximate mechanisms responsible for hibernation termination timing is critical. Northern Idaho ground squirrels (Urocitellus brunneus)-a rare, endemic species threatened with extinction-exhibit substantial variation in hibernation termination phenology, but it is unclear what causes this variation. We attached geolocators to free-ranging squirrels to test the hypothesis that squirrels assess surface conditions in spring before deciding whether to terminate seasonal heterothermy or reenter torpor. Northern Idaho ground squirrels frequently reentered torpor following a brief initial emergence from hibernacula and were more likely to do so earlier in spring or when challenged by residual snowpack. Female squirrels reentered torpor when confronted with relatively shallow snowpack upon emergence, whereas male squirrels reentered torpor in response to deeper spring snowpack. This novel behavior was previously assumed to be physiologically constrained in male ground squirrels by testosterone production required for spermatogenesis and activated by the circannual clock. Assessing surface conditions to decide when to terminate hibernation may help buffer these threatened squirrels against climate change. Documenting the extent to which other hibernators can facultatively alter emergence timing by reentering torpor after emergence will help identify which species are most likely to persist under climate change.

Weather influences survival probability in two coexisting mammals directly and indirectly via competitive asymmetry.

Ecologists have studied the role of interspecific competition in structuring ecological communities for decades. Differential weather effects on animal competitors may be a particularly important factor contributing to the outcome of competitive interactions, though few studies have tested this hypothesis in free-ranging animals. Specifically, weather might influence competitive dynamics by altering competitor densities and/or per-capita competitive effects on demographic vital rates. We used a 9-year data set of marked individuals to test for direct and interactive effects of weather and competitor density on survival probability in two coexisting mammalian congeners: Columbian ground squirrels (Urocitellus columbianus) and northern Idaho ground squirrels (Urocitellus brunneus). Ambient temperature and precipitation influenced survival probability in both species, but the effects of weather differed between the two species. Moreover, density of the larger Columbian ground squirrel negatively impacted survival probability in the smaller northern Idaho ground squirrel (but not vice versa), and the strength of the negative effect was exacerbated by precipitation. That is, cooler, wetter conditions benefited the larger competitor to the detriment of the smaller species. Our results suggest weather-driven environmental variation influences the competitive equilibrium between ecologically similar mammals of differential body size. Whether future climate change leads to the competitive exclusion of either species will likely depend on the mechanism(s) explaining the coexistence of these competing species. Divergent body size and, hence, differences in thermal tolerance and giving up densities offer potential explanations for the weather-dependent competitive asymmetry we documented, especially if the larger species competitively excludes the smaller species from habitat patches of shared preference via interference.

Why hibernate? Tests of four hypotheses to explain intraspecific variation in hibernation phenology

Abstract Hibernation is a remarkable behaviour deployed by a diverse array of endotherms within many clades that greatly reduces metabolic need, but also has somatic costs. Hibernation in modern endotherms is often assumed to be an adaptation allowing animals to avoid extreme thermal conditions or food shortages in seasonal environments. However, many animals hibernate when foraging conditions are energetically profitable, suggesting other causal factors influence hibernation behaviour. Understanding the selection pressures responsible for intraspecific variation in the timing and duration of hibernation can help elucidate the relative evolutionary influences of the ultimate ecological causes of hibernation. We tested four previously proposed mechanistic hypotheses to explain intraspecific variation in hibernation phenology in the federally threatened northern Idaho ground squirrel (Urocitellus brunneus): (1) thermal tolerance, (2) food limitation, (3) predation avoidance and (4) sexual selection. The predation avoidance and sexual selection hypotheses received the most support, although we also found some support for the thermal tolerance and food limitation hypotheses. Heavy squirrels increased hibernation duration regardless of environmental conditions, as predicted solely by the predation avoidance hypothesis. Reproductive males emerged from hibernation earlier in spring than other sex–age classes, a pattern predicted by the sexual selection hypothesis. Temperature and food availability explained a much smaller amount of the variation in hibernation behaviour, only partially supporting predictions of the thermal tolerance and food limitation hypotheses. Our results indicate that animals navigate life‐history trade‐offs between energetic allocation to survival and reproduction via state‐dependent optimization of hibernation phenology. Consequently, any future environmental changes that influence body condition will have implications for population ecology and life‐history evolution of hibernating animals due to stark differences in daily survival probability between hibernation and the active season. Read the free Plain Language Summary for this article on the Journal blog.

Hibernation behavior of a federally threatened ground squirrel: climate change and habitat selection implications

Abstract Hibernation is an adaptation to survive periods of stress, from food limitation or harsh thermal conditions. A key question in contemporary ecology is whether rare, range-restricted species can change their behavior in response to climate change (i.e., through behavioral plasticity). The northern Idaho ground squirrel, Urocitellus brunneus (A. H. Howell, 1928), is a federally threatened species that hibernates for approximately 8 months per year within the bounds of its small range in central Idaho, USA. Changes in temperature, snow accumulation, and summer precipitation, all brought about as a result of climate change, may reduce survival or fecundity of northern Idaho ground squirrels if they cannot adapt to these climate changes. Hibernating species can respond to climate-change-induced thermal challenges in two ways: change their hibernation physiology and behavior (i.e., emergence date or number of torpor bouts) or alter their environment (i.e., change hibernacula depth or location). We explored a suite of intrinsic and extrinsic factors to document the extent to which they influenced hibernation behavior of northern Idaho ground squirrels. Emergence date was positively associated with snowpack and negatively associated with mean winter temperature. Mean minimum skin temperature was negatively associated with canopy closure and slope of a squirrel’s hibernaculum. Duration of the heterothermal period, number of euthermic bouts, and total time spent euthermic were positively associated with body mass. Immergence date and duration of the longest torpor bout were negatively associated with body mass. Warmer temperatures and less snow accumulation in the winter—caused by climate change—likely will cause altered emergence dates. Our results suggest that any future climate-induced changes in snowfall, ambient temperature, food availability, or habitat likely will impact survival of this rare ground squirrel, because such changes will cause changes in hibernation behavior, percent mass loss during hibernation, and duration of the active season when small mammals are more susceptible to predation.

Effects of experimental flea removal and plague vaccine treatments on survival of northern Idaho ground squirrels and two coexisting sciurids

Plague is a non-native disease in North America that reduces survival of many mammals. Previous studies have focused on epizootic plague which causes acute mortality events and dramatic declines in local abundance. We know much less about enzootic plague which causes less punctuated reductions in survival and abundance of infected populations. As a result, enzootic plague is much more difficult to detect because changes in population attributes are more subtle and Yersinia pestis prevalence is likely lower relative to epizootic plague outbreaks. The northern Idaho ground squirrel (Urocitellus brunneus) is a threatened species which coexists with Columbian ground squirrels (Urocitellus columbianus) and yellow-pine chipmunks (Neotamias amoenus) throughout their restricted distribution in central Idaho. Columbian ground squirrels and yellow-pine chipmunks are more abundant and widespread than northern Idaho ground squirrels and both are known hosts for plague. Hence, enzootic plague may be one cause of rarity for northern Idaho ground squirrels but its effect on this threatened species has not been evaluated. We conducted three controlled and randomized field experiments to examine the effects of plague in northern Idaho ground squirrels and the two coexisting species: 1) a plague vaccine experiment, 2) a paired flea-reduction experiment, and 3) a non-paired flea-reduction experiment. For Experiment 1, we hypothesized that if enzootic plague is present, vaccinated animals would have higher survival. Furthermore, Experiments 2 and 3 tested the prediction that untreated, control animals should have lower survival than those in areas where fleas are experimentally removed or reduced because fleas are the main vector for plague. In the plague vaccine experiment, vaccinated chipmunks had 4.65% higher apparent survival compared to chipmunks that received a placebo for intervals when the vaccine is believed to be effective. Apparent annual survival increased for all three species on experimental flea-reduction plots compared to non-treated plots for the paired experiment but results were mixed for the non-paired experiment. Taken together, our results suggest that enzootic plague is present and negatively impacting survival of northern Idaho ground squirrels and two coexisting species.

Winter Versus Summer Habitat Selection in a Threatened Ground Squirrel

ABSTRACTHibernation is a strategy many species employ to survive periods of thermal stress or resource shortage (e.g., harsh thermal conditions, food limitations) and habitat requirements of hibernating species may differ between summer (the active season) and winter (during hibernation). Accounting for seasonal differences in habitat affinities will help ensure that management actions are more beneficial and land‐use policies are more appropriate. The northern Idaho ground squirrel (Urocitellus brunneus) is a federally listed threatened species that is in decline and hibernates for approximately 8 months per year. We collared northern Idaho ground squirrels in Adams County, Idaho from 2013–2017. The majority of northern Idaho ground squirrels we collared selected hibernacula outside of the areas they used during the active season. Furthermore, habitat features of hibernacula locations differed from habitat features of active‐season areas. Hibernacula locations had greater canopy closure compared to active‐season locations (36.9% and 7.0% canopy closure, respectively) and hibernaculum habitat features (particularly distance to nearest log) influenced overwinter survival. Our results suggest that recovery efforts for northern Idaho ground squirrels should include protection and management for the full range of habitat conditions used throughout summer and winter. More broadly, we emphasize the need to identify and protect habitat during all seasons because habitat requirements can differ substantially during different portions of an animal's annual cycle and effective conservation will require management of year‐round habitat needs. © 2020 The Wildlife Society.

Diet of a rare herbivore based on DNA metabarcoding of feces: Selection, seasonality, and survival.

In herbivores, survival and reproduction are influenced by quality and quantity of forage, and hence, diet and foraging behavior are the foundation of an herbivore's life history strategy. Given the importance of diet to most herbivores, it is imperative that we know the species of plants they prefer, especially for herbivorous species that are at risk for extinction. However, it is often difficult to identify the diet of small herbivores because: (a) They are difficult to observe, (b) collecting stomach contents requires sacrificing animals, and (c) microhistology requires accurately identifying taxa from partially digested plant fragments and likely overemphasizes less‐digestible taxa. The northern Idaho ground squirrel (Urocitellus brunneus) is federally threatened in the United States under the Endangered Species Act. We used DNA metabarcoding techniques to identify the diet of 188 squirrels at 11 study sites from fecal samples. We identified 42 families, 126 genera, and 120 species of plants in the squirrel's diet. Our use of three gene regions was beneficial because reliance on only one gene region (e.g., only trnL) would have caused us to miss >30% of the taxa in their diet. Northern Idaho ground squirrel diet differed between spring and summer, frequency of many plants in the diet differed from their frequency within their foraging areas (evidence of selective foraging), and several plant genera in their diet were associated with survival. Our results suggest that while these squirrels are generalists (they consume a wide variety of plant species), they are also selective and do not eat plants relative to availability. Consumption of particular genera such as Perideridia may be associated with higher overwinter survival.

Why is the Northern Idaho Ground Squirrel Rare?

Urocitellus brunneus (northern Idaho ground squirrel) has a geographic range of approximately 1,600 km2 in west-central Idaho. It was listed as Threatened under the US Endangered Species Act in 2000. To assist recovery efforts, we tested three hypotheses that might explain its rarity: 1) specialization on a now uncommon habitat; 2) competition with a larger congener, U. columbianus (Columbian ground squirrel); and 3) anthropogenic impacts. We explored the habitat specialization hypothesis by comparing attributes of sites occupied exclusively by each species with areas occupied alternately by each. Sites occupied by U. brunneus had significantly more bare ground; shallower, rockier, harder soils; higher soil temperatures during the active season; less plant cover; shorter vegetation; lower net annual aboveground productivity; and fewer shrubs than sites occupied by U. columbianus. Discriminant analysis showed U. brunneus could occupy some areas used by U. columbianus, but U. columbianus seldom occupied areas occupied by U. brunneus. U. brunneus also occurred in earlier successional communities and could occupy mesic meadows with high water tables not utilized by U. columbianus. In field observations and arena trials, U. brunneus avoided U. columbianus. In two removal experiments U. brunneus expanded into areas from which U. columbianus had been removed, but vacated when U. columbianus returned. Anthropogenic impacts included habitat conversion, conifer invasion of meadows resulting from timber management and fire suppression practices, systematic poisoning, target shooting, and invasive species; grazing appears to have mixed impacts. U. brunneus is rare due to a combination of habitat specialization, competition, and anthropogenic impacts.

Flea sharing among sympatric rodent hosts: implications for potential plague effects on a threatened sciurid

AbstractFor vector‐borne diseases, the abundance and competency of different vector species and their host preferences will impact the transfer of pathogens among hosts. Sylvatic plague is a lethal disease caused by the primarily flea‐borne bacterium Yersinia pestis. Sylvatic plague was introduced into the western United States in the early 1900s and impacts many species of rodents. Plague may be suppressing populations of the threatened northern Idaho ground squirrel (Urocitellus brunneus) if a competent flea community is allowing plague to be maintained within the few extant sites that support this rare ground squirrel. We collected fleas from four species of sympatric rodents in central Idaho: northern Idaho ground squirrels, Columbian ground squirrels (Urocitellus columbianus), yellow‐pine chipmunks (Tamias amoenus), and deer mice (Peromyscus maniculatus). We evaluated which flea species were present and whether fleas were shared among the rodent community. We documented seven species of fleas among 3356 fleas collected from the four host species of rodents, and all seven species of fleas are known vectors of plague. Three of the seven flea species were detected on all four rodent species, demonstrating potential for spillover of plague (bridge vectors) in the rodent community. We used generalized linear mixed models to evaluate which abiotic and biotic factors influence flea abundance (total number of fleas, regardless of flea species, on each individual host of the four rodent host species). Factors that impacted flea abundance varied among the four host species, but flea abundance: (1) changed over summer depending on host species, (2) was greater on males, and (3) was impacted by summer and winter precipitation depending on host species. Our results suggest this diverse flea community has the capacity to transfer Y. pestis among populations of the four rodents if Y. pestis is present. Furthermore, the disease may be more likely to persist in some locations than others, those that have higher flea abundances, more sympatric hosts, or optimal conditions for fleas, and such high‐risk sites can be identified based on their abiotic and biotic factors.

Forbs Dominate Diets of the Threatened Endemic Northern Idaho Ground Squirrel (Urocitellus brunneus)

Many ground squirrels in western USA persist in degraded grass-dominated habitats where diet choices are more limited than prior to European settlement. This study provided a rare opportunity to investigate ground squirrel diets in relatively undisturbed habitats with a wide range of native diet options. We studied the diet of the northern Idaho ground squirrel, Urocitellus brunneus, a Threatened species under the US Endangered Species Act. It currently has a small, fragmented distribution of about 20 km2 in west-central Idaho. We collected fecal pellets over three years at five study sites with high vascular plant diversity (93 to 133 species) and analyzed them using a microhistological technique. Over all sites and seasons, diets were diverse (74 diet items); 45 species of forbs contributed 86.3% of the observed diet, whereas nine species of graminoids contributed 7.8%. Forb foliage was most utilized, followed by underground parts (roots, bulbs, etc.), and then flowers, whereas seeds were a minor component. Principal components analysis showed that season and age class contributed more to diet variation than sex or site. Kernel regression tracked changes in forb utilization over the active season from foliage to underground parts, and then to flowers and seeds. These data suggest that a prudent restoration strategy for ground squirrel habitat should focus on establishing and maintaining local native forb diversity, especially species with heavily utilized underground parts, flowers, and/or seeds. Legumes and composites are especially important. However, local ecotypes of short-statured grasses such as Poa secunda may also be useful.

Complementary Network-Based Approaches for Exploring Genetic Structure and Functional Connectivity in Two Vulnerable, Endemic Ground Squirrels.

The persistence of small populations is influenced by genetic structure and functional connectivity. We used two network-based approaches to understand the persistence of the northern Idaho ground squirrel (Urocitellus brunneus) and the southern Idaho ground squirrel (U. endemicus), two congeners of conservation concern. These graph theoretic approaches are conventionally applied to social or transportation networks, but here are used to study population persistence and connectivity. Population graph analyses revealed that local extinction rapidly reduced connectivity for the southern species, while connectivity for the northern species could be maintained following local extinction. Results from gravity models complemented those of population graph analyses, and indicated that potential vegetation productivity and topography drove connectivity in the northern species. For the southern species, development (roads) and small-scale topography reduced connectivity, while greater potential vegetation productivity increased connectivity. Taken together, the results of the two network-based methods (population graph analyses and gravity models) suggest the need for increased conservation action for the southern species, and that management efforts have been effective at maintaining habitat quality throughout the current range of the northern species. To prevent further declines, we encourage the continuation of management efforts for the northern species, whereas conservation of the southern species requires active management and additional measures to curtail habitat fragmentation. Our combination of population graph analyses and gravity models can inform conservation strategies of other species exhibiting patchy distributions.

Restoring habitat for the northern Idaho ground squirrel (Urocitellus brunneus brunneus): Effects of prescribed burning on dwindling habitat

Land use and fire exclusion have contributed to an increase in ponderosa pine (Pinus ponderosa) forest extent and density in west-central Idaho. Open areas within ponderosa pine forests are decreasing, thus reducing habitat for the endemic northern Idaho ground squirrel (NIDGS; Urocitellus brunneus brunneus). In 2000, the NIDGS was listed on the Endangered Species Act as threatened in part due to habitat loss. Therefore, recovery plans encourage the use of burning to expand meadows and open corridors. We gathered data on habitat attributes altered by prescribed fall burning at three sites selected for habitat restoration. Each site was divided into two units: a CONTROL unit occupied by the NIDGS and a BURN unit not occupied by the NIDGS. We sought to assess whether the prescribed fall burning fulfilled management goals and generated habitat features similar to CONTROL conditions that are suitable for the NIDGS. Data were collected before the fall prescribed burn and one and two years post-burn. Before the prescribed burn, BURN units had higher tree densities and canopy cover than CONTROL units; however, the prescribed fall burn did not reduce tree density or canopy cover one year later. Understory height in the BURN unit decreased slightly post-burn, approaching CONTROL conditions. Majority of understory characteristics were similar between CONTROL and BURN units before, one, and two years after the burn, but understory community structure remained strongly dissimilar. This study preliminarily examines NIDGS habitat and is the first paper to evaluate the effects of prescribed burning as restoration practices to create NIDGS habitat. Key habitat attributes associated with NIDGS presence include tree canopy cover, understory height and community structure, and litter depth. Management goals were not attained within the stated timeline, one year post-burn, or even two years after prescribed burn was implemented. Based on our results, managers should consider extending the timeframe for restoration goal achievement and perhaps modifying goals to include changes in tree canopy cover, understory height and community structure, and litter depth. Future efforts should monitor beyond two years post-fire, focus on long-term effects of prescribed burning, and examine how repeat burns may help attain habitat restoration goals.

Relationship between habitat characteristics and densities of southern Idaho ground squirrels

Many wildlife species living in sagebrush-steppe habitats of the Intermountain West of the United States have experienced population declines. Effective management of such species, especially restoration efforts, is contingent on understanding relationships between habitat characteristics and population densities of the target species. Unfortunately, even such basic information is often lacking. The goal of this 2-year study was to determine the relationship between southern Idaho ground squirrel (Urocitellus endemicus) population densities and habitat variables: soils (texture), topography (slope, aspect), and vegetation (canopy cover, species diversity). We measured population density indirectly through burrow entrance counts and categorized them into high-burrow and low-burrow densities. We used logistic regression and Akaike's Information Criterion to identify a best subset of models. We employed model averaging and calculated odds ratios for averaged parameter estimates found in the best models. A high density of burrows was associated with greater percentages of silt; east-facing aspects; greater plant species diversity; and greater cover of perennial grasses, perennial grasses and forbs, and native perennial forbs. Low burrow density was associated with greater percentages of sand; south-facing aspects; greater cover of exotic annuals; and lesser plant species diversity. Management of southern Idaho ground squirrel habitat should focus on protecting areas with existing native vegetation and restoring native, perennial vegetation in areas that are infested with exotic annuals, especially in areas possessing suitable soil types and topographic features. © 2013 The Wildlife Society.

A Starting Point: An Ecosystem of Reference for Habitat Restoration of the Northern Idaho Ground Squirrel, Urocitellus brunneus brunneus

The Northern Idaho Ground Squirrel (NIDGS, Urocitellus brunneus brunneus) is threatened by habitat loss due to fire exclusion in west-central Idaho. Increases in Ponderosa Pine (Pinus ponderosa) density and extent have closed historically open meadows. Management practices for NIDGS recovery include thinning and burning to reduce tree encroachment. Baseline habitat data help create restoration goals and refine present management plans, but no pristine reference sites exist for the NIDGS, due to 100 y of land use and a lack of historical records. Therefore, we provided the first quantitative habitat descriptions of NIDGS habitat at 7 currently occupied sites that may be useful as an ecosystem of reference. We chose habitat attributes that are likely important to NIDGS, as well as attributes that are potentially altered by restoration treatments, which included overstory canopy cover, tree density, ground cover, litter depth, and soil texture. Habitat attributes were described with Bayesian 95% credibility intervals. Sites occupied by NIDGS had tree canopy cover of 10 to 15%, tree densities of 64 to 118 trees/ha, and understory height was 20 to 25 cm. Understory vegetation of occupied habitat consisted of 20 to 30 species, while across-site richness was 153 species. We also identified 15 understory species with the highest constancy and cover across the 7 sites. Litter depth was 0.7 to 0.9 cm, and the soil texture was clay loam. Our study provides valuable baseline information about NIDGS habitat. Managers may use our results to develop appropriate restoration targets when implementing habitat restoration. Information on occupied habitat may increase the efficacy of currently implemented restoration techniques and provide knowledge to be used in an adaptive management framework.

Species limits and integrated taxonomy of the Idaho ground squirrel (Urocitellus brunneus): genetic and ecological differentiation

Allocation of evolutionary divergence into species level versus subspecies ranks is critical for conservation and management. Urocitellus brunneus (Idaho ground squirrel; formerly Spermophilus brunneus) is currently apportioned into 2 subspecies, U. b. brunneus and U. b. endemicus, but recent studies have suggested elevation to distinct species based on differences in pelage, bacular morphology, genetic data, timing of life-history cycle, and behavior. Following recent movements toward integrated taxonomy, we use the cohesion species concept to test whether both genetic and ecological data support species-level classification of U. b. brunneus and U. b. endemicus. Eight microsatellite loci and mitochondrial DNA (mtDNA) sequence data were generated for 339 individuals from 14 localities for U. b. brunneus and 312 individuals from 11 localities for U. b. endemicus .T he null hypothesis of genetic interchangeability was tested with 2 independent data sets. First, we estimated an mtDNA gene tree from control region and cytochrome-b sequences via parsimony, maximum-likelihood, and Bayesian analyses. We then tested for evidence of recent migration using Bayesian clustering and coalescence analyses of microsatellite data. The 2nd null hypothesis, that of ecological exchangeability, was tested using an ecological niche-model analysis and a review of the literature based on morphology, habitat characteristics, and behavior. Although divergence of mtDNA sequences between the subspecies was modest (,1%), there are no haplotypes shared between the 2 taxa. There is strong support for monophyly of mtDNA haplotyes of U. b. endemicus (posterior probability 5 0.94), with those from U. b. brunneus forming a basal grade. No evidence of recent gene flow was detected; the Bayesian clustering algorithms of mutlilocus genotype data indicated separate ancestry for both U. b. brunneus and U. b. endemicus. The ecological-niche model showed a nonoverlapping niche for each taxon, allowing for the possibility of differential adaptation. We reject both null hypotheses based on the data, which supports elevation of U. b. brunneus and U. b. endemicus as distinct species.

Changes in Taxonomic Nomenclature and Conservation Status of Ground Squirrel Species: Implications for Pesticide Labeling and Use of Zinc Phosphide Pesticide Products

Author(s): O’Hare, Jeanette R.; Eisemann, John D.; Fagerstone, Kathleen A. | Abstract: The taxonomic classification of species and their protection status have important pesticide regulatory implications, particularly regarding product label language. Changes in nomenclature may cause confusion for both pesticide applicators and regulators. Such changes may also result in the naming of new species in need of protection, or conversely species whose protected status may no longer be warranted. Over the past several years there have been gradual taxonomic changes within the genus Spermophilus. This change has resulted in splitting Townsend’s ground squirrel (Spermophilus townsendii) into 3 distinct species. In addition to S. townsendii, the Piute ground squirrel (Spermophilus mollis) and Merriam’s ground squirrel (Spermophilus canus) are now recognized. The Townsend’s ground squirrel, as now classified, is restricted to a small region in southwestern Washington. The species with the largest distribution, that was formally included in S. townsendii, is now the Piute ground squirrel (S. mollis). Zinc phosphide pesticide products are used to control a number of ground squirrel species including Townsend’s. However, based on the revised nomenclature, populations of the 2 new species (Piute and Merriam’s ground squirrels) may not be controlled using these zinc phosphide products under existing labels, even though those same populations were previously considered Townsend’s ground squirrels and could be controlled with zinc phosphide products. Potential conflicts with state and federal laws regarding protection of certain species must also be considered. The reclassification of Townsend’s ground squirrel recognizes new species and existing subspecies that are protected or are being considered for protection. In addition, subspecies of the Idaho ground squirrel (Spermophilus brunneus) are afforded various levels of protection under federal and state laws. A discussion of temporal taxonomy changes, geographic distribution, and conservation status of the “Townsend’s ground squirrel” complex and the Idaho ground squirrel is presented here to support the decision process needed to develop appropriate label language for zinc phosphide pesticide products.

Genetic diversity and population divergence in fragmented habitats: Conservation of Idaho ground squirrels

The Idaho ground squirrel, which consists of a northern (Spermophilus brunneus brunneus) and a southern subspecies (S. b. endemicus), has suffered from habitat loss and fragmentation, resulting in a reduction in both numbers and geographic range of the species. The northern Idaho ground squirrel (NIDGS) is listed as a threatened subspecies under the Endangered Species Act, and the southern Idaho ground squirrel (SIDGS) is a candidate. Because Idaho ground squirrel populations are small and often isolated, they are susceptible to inbreeding and loss of genetic diversity through drift. This research evaluates levels of genetic diversity and patterns of population divergence in both subspecies of Idaho ground squirrels. We hypothesized that NIDGS would exhibit lower genetic diversity and greater population divergence due to a longer period of population isolation relative to most SIDGS populations. Genetic diversity and divergence were quantified using 8 microsatellite loci. Contrary to expectations, SIDGS populations exhibited consistently lower levels of microsatellite diversity. Additionally, NIDGS exhibited only modest divergence among populations, while divergence levels among SIDGS populations were highly varied. Preliminary evaluations of mitochondrial DNA diversity and structure revealed lower diversity in NIDGS and some differences in gene flow that warrant further study. Based on our results, we suggest different management strategies for the two subspecies. Habitat restoration appears to be the most desirable conservation strategy for NIDGS populations. In contrast, low genetic diversity observed in SIDGS may warrant supplementation of isolated populations through translocations or captive breeding to mitigate further loss of genetic variability.

Population Genetic Structure of the Northern Idaho Ground Squirrel (Spermophilus brunneus brunneus)

Spermophilus brunneus is one of the rarest species of North American ground squirrels. It occurs in just five counties in western Idaho. We sampled blood from 14–64 individuals in 11 populations of the northern subspecies S. b. brunneus . Analyses of allozymes at five polymorphic loci revealed significant population structure ( F st = 0.167). Four populations located within a 2-km radius in Bear Meadow (Adams Co.) were indistinguishable with respect to allelic frequencies (Nei's D = 0.002), but the remaining seven, more distant populations (also in Adams Co.) were differentiated from this group and from each other. F ST values ranged from 0.034 to 0.124 when the four populations in Bear Meadow were pooled and compared with each of the seven isolated populations. Regression of Slatkin's M against geographic distance among the 55 pairwise comparisons of populations suggested a strong effect of isolation-by-distance, consistent with a one-dimensional stepping-stone model of gene flow. Significant genetic structure in S. b. brunneus populations apparently is due to genetic drift in populations with small Ne (i.e., 20–50), reinforced by lack of gene flow following recent habitat fragmentation. Fragmentation results from the shrinking of meadows due to invasion by conifers, itself the consequence of fire suppression in the past 100 years.

Characterization of microsatellite loci in the northern Idaho ground squirrel Spermophilus brunneus brunneus.

Molecular EcologyVolume 6, Issue 4 p. 399-400 Characterization of microsatellite loci in the Northern Idaho ground squirrel Spermophilus brunneus brunneus B. May, B. May Department of Animal Science, Meyer Hall, University of California, Davis, CA 95616, USA, Department of Natural Resources, Fernow Hall, Cornell University, Ithaca, NY 14853, USA,Search for more papers by this authorT. A. Gavin, T. A. Gavin Department of Natural Resources, Fernow Hall, Cornell University, Ithaca, NY 14853, USA,Search for more papers by this authorP. W. Sherman, P. W. Sherman Section of Neurobiology and Behavior, Mudd Hall Cornell University, Ithaca, NY 14853, USASearch for more papers by this authorT. M. Korves, T. M. Korves Department of Animal Science, Meyer Hall, University of California, Davis, CA 95616, USA,Search for more papers by this author B. May, B. May Department of Animal Science, Meyer Hall, University of California, Davis, CA 95616, USA, Department of Natural Resources, Fernow Hall, Cornell University, Ithaca, NY 14853, USA,Search for more papers by this authorT. A. Gavin, T. A. Gavin Department of Natural Resources, Fernow Hall, Cornell University, Ithaca, NY 14853, USA,Search for more papers by this authorP. W. Sherman, P. W. Sherman Section of Neurobiology and Behavior, Mudd Hall Cornell University, Ithaca, NY 14853, USASearch for more papers by this authorT. M. Korves, T. M. Korves Department of Animal Science, Meyer Hall, University of California, Davis, CA 95616, USA,Search for more papers by this author First published: 31 October 2003 https://doi.org/10.1046/j.1365-294X.1997.00203.xCitations: 28 Bernie May Tel.: +1-916-754 8123, Fax: +1-916-752-0175. E-mail: [email protected] AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article.Citing Literature Volume6, Issue4April 1997Pages 399-400 RelatedInformation