Bradley J. Swanson

Central Michigan University | CMU · Department of Biology

The threat to biodiversity posed by urban expansion is well researched and supported. Since the late 1990s, the field of urban ecology has been expanding along with the developed landscapes it studies. Past reviews have shown unequal publication rates in urban ecology literature for taxonomic groups and research locations. Herein, we explore differ...

An endangered black-footed ferret female that died in 1988 with no living descendants in the current population was successfully cloned from cryopreserved cells using cross-species somatic cell nuclear transfer, producing three healthy kits. Incorporating progeny from these clones would provide an 8th founder to the breeding program and increase ge...

Small, fragmented populations are at greater risk of extirpation due to reduced genetic diversity from inbreeding and genetic drift. These processes ultimately decrease individual fitness and reduce the ability of a population to adapt. Hill's thistle (Cirsium hillii) is classified as a threatened species throughout much of its range, primarily due...

Emerging infectious diseases have recently increased in wildlife and can result in population declines and the loss of genetic diversity in susceptible populations. As populations of impacted species decline, genetic diversity can be lost, with ramifications including reduced effective population size and increased population structuring. For speci...

American martens (Martes americana) in the northern Lower Peninsula of Michigan (NLP) represent a reintroduced and isolated population that is the southern-most distributed marten population in eastern North America. During 2005–2006, we conducted a radiotelemetry and track-survey study of martens in the NLP. We estimated home-range size and patter...

Dragonflies reside in both aquatic and terrestrial environments, depending on their life stage, necessitating the conservation of drastically different habitats; however, little is understood about how nymph and adult dragonflies function as metapopulations within connected habitat. We used genetic techniques to examine nymphs and adults within a s...

Wild rice (Zizania spp.) has ecological and cultural importance in the Great Lakes region, but has been declining due to habitatloss and fragmentation. We investigated the potential impact of bed area and isolation by distance on genetic structure, repro-ductive effort, and morphometrics in populations of two wild rice species (Z. palustris and Z....

Wild rice (Zizania spp.) has ecological and cultural importance in the Great Lakes region, but has been declining due to habitat loss and fragmentation. We investigated the potential impact of bed area and isolation by distance on genetic structure, reproductive effort, and morphometrics in populations of two wild rice species (Z. palustris and Z....

Population genetic analyses of species inhabiting fragmented landscapes are essential tools for conservation. Occasionally, analyses of fragmented populations find no evidence of isolation, even though a barrier to dispersal is apparent. In some cases, not enough time may have passed to observe divergence due to genetic drift, a problem particularl...

Reintroduction programs have been pivotal in augmenting populations of fishers (Pekania pennanti (Erxleben, 1777)) and re-establishing them to their former range in North America. The majority of reintroduction efforts in fishers have been considered demographically successful, but reintroductions can alter genetic population structure and success...

Wildlife conservation and management approaches typically focus on demographic measurements to assess population viability over both short and long periods. However, genetic diversity is an important predictor of long term population vitality. We investigated the pattern of change in genetic diversity in a large and likely isolated moose (Alces alc...

Simulation code

Isle Royale moose microsatellite genotypes and mtDNA data

Structure penalized likelihood plot for all samples from all time periods Circles represent the mean likelihood and bars show the 95% confidence interval for each estimate.

Reintroductions are an important conservation and management technique used to restore extirpated populations. Negative genetic consequences (e.g., diversity loss, bottlenecks, inbreeding) are often an unintentional result of reintroductions, due to a small number of founders or suboptimal habitat at release sites. American martens (Martes american...

Population studies are widely used in conservation and management efforts, but acquiring necessary data sets can be difficult. Convenience sampling or camera monitoring may result in biased outcomes, while explicit approaches such as genetic analysis may be impractical due to cost and time. Traditional mark recapture methods are frequently intrusiv...

Small and isolated populations often exhibit low genetic diversity due to drift and inbreeding, but may simultaneously harbour adaptive variation. We investigate spatial distributions of immunogenetic variation in American badger subspecies (Taxidea taxus), as a proxy for evaluating their evolutionary potential across the northern extent of the spe...

Appendix S1. Verification of MHC Genotypes. Table S1. Characteristics of microsatellite DNA loci used to measure neutral genetic variation in the Eastern Massasauga (Gibbs et al. 1998; H. L. Gibbs, pers. comm.). Table S2. Microsatellite alleles and allele frequencies for Eastern Massasaugas in (A) Clinton County, (B) Piatt County, and (C) Cook Co...

Genetic diversity is fundamental to maintaining the long-term viability of populations, yet reduced genetic variation is often associated with small, isolated populations. To examine the relationship between demography and genetic variation, variation at hypervariable loci (e.g., microsatellite DNA loci) is often measured. However, these loci are s...

Multiple paternity is widespread among animals. Within snakes, multiple paternity has been well-documented with the exception of the family Elapidae. However, variation in the frequency of multiple paternity among populations is poorly documented and warrants further investigation. Here, we provide evidence for multiple paternity in three wild popu...

The consequences of biological invasions warrant continued research on the mechanisms underlying the spread of exotic species, yet interspecific behavioral interactions are largely overlooked as a contributing factor or consequence of introductions of exotic species. Our study evaluates how native crayfish species, Cambarus bartonii (Fabricius, 179...

Like some species of pika (Ochotona) and tree squirrel (Tamiasciurus), the banner-tailed kangaroo rat (Dipodomys spectabilis) is a solitary, philopatric larder-hoarder that practices unisexual territoriality. Seeking to understand how this unusual combination of traits might influence the mating system, we used systematic trapping at mounds (burrow...

Ringed seals (Pusa hispida) are broadly distributed in seasonally ice covered seas, and their survival and reproductive success is intricately linked to sea ice and snow. Climatic warming is diminishing Arctic snow and sea ice and threatens to endanger ringed seals in the foreseeable future. We investigated the population structure and connectednes...

A spatial gradient in the interactions between American minks (Neovison vison) and muskrats (Ondatra zibethicus) occurs in the Hudson’s Bay Company fur harvest returns of Canada. Evidence for strong dependence of minks on muskrats exists in northwestern Canada, whereas evidence for weaker interactions exists in central and eastern Canada. We tested...

Background/Question/Methods Ambystomid salamanders utilize ephemeral ponds for breeding and larval habitat. My focal species are the spotted (Ambystoma maculatum) and the blue-spotted complex (Ambystoma laterale and Ambystoma laterale-jeffersonianum) salamanders. In an initial study in June 2012, I found two ponds, one with only Ambystoma maculat...

Populations of Wood Turtles, Glyptemys insculpta, have steadily decreased over the past 30 yr because of habitat destruction and degradation. We sampled Wood Turtles from three areas in Michigan, USA, to characterize populations, quantify demographic trends, and measure the effect of declining population size on genetic diversity. Wood Turtle sampl...

The eastern massasauga Sistrurus catenatus catenatus is a declining species for which a captive breeding program was established in 2006. To effectively manage wild and captive populations, an understanding of genetic diversity within the species is necessary. We analyzed mitochondrial DNA sequences of 186 individuals: 109 wild snakes from 34 U.S....

The enactment of legal policies is often recommended to prevent anthropogenic introductions of invasive species. In this paper, we evaluated the effectiveness of proactive state legislative policies in deterring colonization by rusty crayfish (Orconectes rusticus) and the expected spread into previously uninvaded states using network-based spatial...

Population genetics has fueled a substantial growth in studies of dispersal, a life-history trait that has important applications in ecology and evolution. Mammals typically exhibit male-biased gene flow, so this pattern often serves as a null hypothesis in empirical studies. Estimation of dispersal using population genetics is not without biases,...

Background/Question/Methods Urbanization has led to habitat loss, some of which may be replaced by green roofs. We evaluated colonization rates of plants on green roofs to test two hypotheses: 1) native and invasive plants colonize green roofs at equal rates and 2) colonization rates of green roofs are independent of roof area, roof age, number o...

Background/Question/Methods Loss of genetic diversity is a major factor in extinction for small populations. Populations with high levels of genetic diversity are less likely to suffer the negative effects of inbreeding that can cause a population to decline. Translocating individuals into a critically small population mimics natural gene flow an...

Background/Question/Methods Many of the characteristics indicative of an invasive species are found in the rusty crayfish (Orconectes rusticus): high abundance, high dispersal rates, high genetic diversity, and nonspecific habitat requirements. Within the Upper Susquehanna River Basin, NY, rusty crayfish have colonized some river sections while av...

In Canada, three subspecies of American badgers (Taxidea taxus (Schreber, 1777)) traditionally are identified; two of which are listed as endangered because of their restricted geographic range and low population sizes. To verify their subspecific designations and genetic insularity, we analyzed mitochondrial control region sequences within and amo...

The black-footed ferret (Mustela nigripes) went extinct in the wild when the last 18 known ferrets were captured for a captive-breeding program. Following the success of the captive-breeding program, 146 genetically nonessential ferrets were released at the Conata Basin, South Dakota, from 1996 to 1999. We conducted a genetic analysis of the Conata...

We analyzed the hypothesized relationships of temporal, spatial, and harvest trends with frequency of red fox (Vulpes vulpes) color morphs in 57 Hudson's Bay Company posts over a 20- to 26-year period, but found none of the strong relationships postulated to exist. A meta-analysis of each data set suggested a weak inverse relationship between latit...

We investigated population structure and genetic diversity for bobcats (Lynx rufus) in Michigan, USA, which are distributed throughout the upper peninsula (UP) and the northern half of the lower peninsula (LP) of Michigan. Specifically, we assessed the influence of natural and artificial barriers to dispersal on the genetic population structure of...

Obtaining accurate estimates of fisher (Martes pennanti) population abundance is challenging to resource management agencies given the large home ranges and low densities at which fisher occur. Current methods for estimating population abundance are expensive in terms of equipment required and hours worked indicating a need for a less labor and equ...

. We found high levels of genetic variation (H=0.83; A=16) and low levels of genetic differentiation (F ST =0.006) in the system. The three areas exist as a single population and there was a low rate (11%) of misassignment across the sites. There was initial evidence of a genetic bottleneck in two of the three populations and the system as a whole....

The forage-selection hypothesis (FSH) explains sexual segregation in ungulates as a function of different dietary requirements producing different levels of habitat optimality, whereas the reproductive-strategy hypothesis (RSH) explains sexual segregation as a function of different survival strategies between the sexes. Based on observations of hab...

Rastreo de carrete y cordel es un método innovador y económico para registrar los desplazamientos de mamíferos pequeños en una variedad de hábitats, y podría tener una aplicación importante en estudios relacionados con la conservación. Sin embargo, los potenciales efectos negativos déste método no han sido investigados. Documentamos los efectos de...

Reintroduced populations face a genetic bottleneck due to the founding event of the reintroduction. Bringing in additional animals from different locations, or at different times, can restore genetic variation to a reintroduced population and offset the founder event. The reintroduced population of martens in Michigan came from 3 different location...

Sporadic reports of cougars (Puma concolor) have occurred in Michigan since its official classification as extirpated in the 1930s. We collected 297 scats from 12 areas in Michigan with heavy sighting reports of cougars. Ten scats produced DNA profiles consistent with cougars. One scat was identified as having a North American origin; the other nin...

We monitored the movements of ringed seals using radio and ultra-sonic tags during the winter – spring period when the seals were occupying shorefast ice and using satellite-linked transmitters in summer and fall when the seals ranged away from their winter sites. In the shorefast ice habitat, the home ranges of 27 breeding males ranged from < 1 km...

Reintroduced populations face a genetic bottleneck due to the founding event of the reintroduction. Bringing in additional animals from different locations, or at different times, can restore genetic variation to a reintroduced population and offset the founder event. The reintroduced population of martens in Michigan came from 3 different location...

Obtaining a sufficient number of DNA samples from ice-breeding marine phocids, in a noninvasive manner, has proven difficult and has limited the ability to use molecular genetics on these species. We evaluate the ability to genotype ringed seals using a novel source of DNA, skin cells shed by the seal as it moults on sea ice. We found that shed ski...

Reintroduced populations are generally smaller and more isolated than native populations; thus even when reintroduced populations are demographically stable, a lack of genetic variation may present a threat to long-term persistence. We examined the demographic structure and genetic variation of the marten reintroduction into the Upper Peninsula of...

The illegal harvest of natural resources (i.e., poaching) has the potential to threaten the persistence of many plant and animal species. In Michigan bobcats (Lynx rufus) are distributed throughout the Upper Peninsula (UP) and the northern half of the Lower Peninsula (LP) and are a biologically and economically important species. The popularity of...

Foxes in the Greater Yellowstone Ecosystem are reported to show high frequencies of blonde and gray coat colors. A survey of park sighting records showed that the frequency of the novel coat colors significantly increases at elevations greater than 2300 m, suggesting some form of elevational isolation. We evaluated the degree of genetic separation...

Keywords:Dipodomys;Heteromyidae;kangaroo rats;microsatellites;pocket mice

Based on partial autocorrelation analysis, 20 ermine (Mustela erminea) populations in Manitoba, Ontario, and Quebec demonstrated cyclic dynamics characterized by a latitudinal gradient of decreasing first-order feedback and increasing negativity of second-order feedback. Most of these populations exhibited three cyclic peaks and a 10-year interval...

We examined the degree and cause of intraspecific synchrony in population dynamics between 29 - 42 populations for each of seven mammalian species. Regions containing multiple populations with similar dynamics were identified using cluster ananlysis. Two explanations for the observed syncrhony were evaluated, dispersal and the "Moran effect", a spa...

I examined the prevalence of autocorrelation in mammalian, avian, and precipitation time series, how well autocorrelation in the environment translates into autocorrelation in animal populations, and length of the time series needed to accurately characterize the degree of autocorrelation. These are important questions because more‐complex populati...

We analyzed the hypothesized relationships of temporal, spatial, and harvest trends with frequency of red fox (Vulpes vulpes) color morphs in 57 Hudson's Bay Company posts over a 20-to 26-year period, but found none of the strong relationships postulated to exist. A meta-analysis of each data set suggested a weak inverse relationship between latitu...

The purpose of this study was to evaluate demographic and genetic methods of estimating the effective population size of a population. Effective population size (Ne ) describes how populations lose genetic variation due to random genetic drift. Reduced genetic variation increases inbreeding, which, increases the expression of deleterious traits, pr...