Spatial genetic structure in American black bears (Ursus americanus): female philopatry is variable and related to population history.

Previously, American black bears (Ursus americanus) were thought to follow the pattern of female philopatry and male-biased dispersal. However, recent studies have identified deviations from this pattern. Such flexibility in dispersal patterns can allow individuals greater ability to acclimate to changing environments. We explored dispersal and spatial genetic relatedness patterns across ten black bear populations-including long established (historic), with known reproduction >50 years ago, and newly established (recent) populations, with reproduction recorded <50 years ago-in the Interior Highlands and Southern Appalachian Mountains, United States. We used spatially explicit, individual-based genetic simulations to model gene flow under scenarios with varying levels of population density, genetic diversity, and female philopatry. Using measures of genetic distance and spatial autocorrelation, we compared metrics between sexes, between population types (historic and recent), and among simulated scenarios which varied in density, genetic diversity, and sex-biased philopatry. In empirical populations, females in recent populations exhibited stronger patterns of isolation-by-distance (IBD) than females and males in historic populations. In simulated populations, low-density populations had a stronger indication of IBD than medium- to high-density populations; however, this effect varied in empirical populations. Condition-dependent dispersal strategies may permit species to cope with novel conditions and rapidly expand populations. Pattern-process modeling can provide qualitative and quantitative means to explore variable dispersal patterns, and could be employed in other species, particularly to anticipate range shifts in response to changing climate and habitat conditions.

Trap array configuration influences estimates and precision of black bear density and abundance.

Spatial capture-recapture (SCR) models have advanced our ability to estimate population density for wide ranging animals by explicitly incorporating individual movement. Though these models are more robust to various spatial sampling designs, few studies have empirically tested different large-scale trap configurations using SCR models. We investigated how extent of trap coverage and trap spacing affects precision and accuracy of SCR parameters, implementing models using the R package secr. We tested two trapping scenarios, one spatially extensive and one intensive, using black bear (Ursus americanus) DNA data from hair snare arrays in south-central Missouri, USA. We also examined the influence that adding a second, lower barbed-wire strand to snares had on quantity and spatial distribution of detections. We simulated trapping data to test bias in density estimates of each configuration under a range of density and detection parameter values. Field data showed that using multiple arrays with intensive snare coverage produced more detections of more individuals than extensive coverage. Consequently, density and detection parameters were more precise for the intensive design. Density was estimated as 1.7 bears per 100 km2 and was 5.5 times greater than that under extensive sampling. Abundance was 279 (95% CI = 193-406) bears in the 16,812 km2 study area. Excluding detections from the lower strand resulted in the loss of 35 detections, 14 unique bears, and the largest recorded movement between snares. All simulations showed low bias for density under both configurations. Results demonstrated that in low density populations with non-uniform distribution of population density, optimizing the tradeoff among snare spacing, coverage, and sample size is of critical importance to estimating parameters with high precision and accuracy. With limited resources, allocating available traps to multiple arrays with intensive trap spacing increased the amount of information needed to inform parameters with high precision.

Influence of drift and admixture on population structure of American black bears (Ursus americanus) in the Central Interior Highlands, USA, 50 years after translocation.

Bottlenecks, founder events, and genetic drift often result in decreased genetic diversity and increased population differentiation. These events may follow abundance declines due to natural or anthropogenic perturbations, where translocations may be an effective conservation strategy to increase population size. American black bears (Ursus americanus) were nearly extirpated from the Central Interior Highlands, USA by 1920. In an effort to restore bears, 254 individuals were translocated from Minnesota, USA, and Manitoba, Canada, into the Ouachita and Ozark Mountains from 1958 to 1968. Using 15 microsatellites and mitochondrial haplotypes, we observed contemporary genetic diversity and differentiation between the source and supplemented populations. We inferred four genetic clusters: Source, Ouachitas, Ozarks, and a cluster in Missouri where no individuals were translocated. Coalescent models using approximate Bayesian computation identified an admixture model as having the highest posterior probability (0.942) over models where the translocation was unsuccessful or acted as a founder event. Nuclear genetic diversity was highest in the source (AR = 9.11) and significantly lower in the translocated populations (AR = 7.07-7.34; P = 0.004). The Missouri cluster had the lowest genetic diversity (AR = 5.48) and served as a natural experiment showing the utility of translocations to increase genetic diversity following demographic bottlenecks. Differentiation was greater between the two admixed populations than either compared to the source, suggesting that genetic drift acted strongly over the eight generations since the translocation. The Ouachitas and Missouri were previously hypothesized to be remnant lineages. We observed a pretranslocation remnant signature in Missouri but not in the Ouachitas.

Insecticidal activity of Bacillus thuringiensis Cry1Bh1 against Ostrinia nubilalis (Hubner) (Lepidoptera: Crambidae) and other lepidopteran pests.

Bacillus thuringiensis is an important source of insect resistance traits in commercial crops. In an effort to prolong B. thuringiensis trait durability, insect resistance management programs often include combinations of insecticidal proteins that are not cross resistant or have demonstrable differences in their site of action as a means to mitigate the development of resistant insect populations. In this report, we describe the activity spectrum of a novel B. thuringiensis Cry protein, Cry1Bh1, against several lepidopteran pests, including laboratory-selected B. thuringiensis-resistant strains of Ostrinia nubilalis and Heliothis virescens and progeny of field-evolved B. thuringiensis-resistant strains of Plutella xylostella and Spodoptera frugiperda. Cry1Bh1 is active against susceptible and B. thuringiensis-resistant colonies of O. nubilalis, P. xylostella, and H. virescens in laboratory diet-based assays, implying a lack of cross-resistance in these insects. However, Cry1Bh1 is not active against susceptible or Cry1F-resistant S. frugiperda. Further, Cry1Bh1 does not compete with Cry1Fa or Cry1Ab for O. nubilalis midgut brush border membrane binding sites. Cry1Bh1-expressing corn, while not completely resistant to insect damage, provided significantly better leaf protection against Cry1Fa-resistant O. nubilalis than did Cry1Fa-expressing hybrid corn. The lack of cross-resistance with Cry1Ab and Cry1Fa along with independent membrane binding sites in O. nubilalis makes Cry1Bh1 a candidate to further optimize for in-plant resistance to this pest.

Variation in the ITS-1 and ITS-2 rRNA genomic regions of Cytauxzoon felis from bobcats and pumas in the eastern United States and comparison with sequences from domestic cats.

Cytauxzoon felis, a tick-borne protozoan parasite, is the causative agent of cytauxzoonosis in domestic cats in the United States. The natural reservoir for this parasite is the bobcat (Lynx rufus), which typically does not develop clinical signs. Although not likely important reservoirs, C. felis has also been detected in pumas (Puma concolor) in Florida and Louisiana. Recent studies suggest that specific genotypes of C. felis that circulate in domestic cats may be associated with variable clinical outcomes and specific spatial locations. In the current study, we investigated the intraspecific variation of the C. felis internal transcribed spacer (ITS)-1 and ITS-2 rRNA regions from 145 wild felids (139 bobcats and six pumas) from 11 states (Florida, Georgia, Kansas, Kentucky, Louisiana, Missouri, North Carolina, North Dakota, South Carolina, Oklahoma, and Pennsylvania). Unambiguous ITS-1 and ITS-2 data were obtained for 144 and 112 samples, respectively, and both ITS-1 and ITS-2 sequences were obtained for 111 (77%) samples. For the ITS-1 region, sequences from 65 samples collected from wild felids were identical to those previously reported in domestic cats, while the other 79 sequences were unique. C. felis from 45 bobcats and one puma had ITS-1 sequences identical to the most common sequence reported from domestic cats. Within the ITS-2 region, sequences from 49 bobcats were identical to those previously reported in domestic cats and 63 sequences were unique (with some occurring in more than one bobcat). The most common ITS-2 sequence from domestic cats was also common in wild felids (31 bobcats and a puma). Samples from three pumas from Florida and two bobcats from Missouri had a 40- or 41-bp insert in the ITS-2 similar to one described previously in a domestic cat from Arkansas. Additionally, a previously undescribed 198- or 199-bp insert was detected in the ITS-2 sequence from four bobcats. Collectively, based on combined ITS-1 and ITS-2 sequences, five different genotypes were detected in the wild felids. Genotype ITSa was the most common genotype (11 bobcats and one puma) and fewer numbers of ITSb, ITSe, ITSg, and ITSi were detected in bobcats. These data indicate that, based on ITS-1 and ITS-2 sequences, numerous C. felis strains may circulate in wild felids.

Historic occurrence of the amphibian chytrid fungus Batrachochytrium dendrobatidis in hellbender Cryptobranchus alleganiensis populations from Missouri.

The pathogenic fungus Batrachochytrium dendrobatidis (Bd) was recently detected in Missouri hellbender Cryptobranchus alleganiensis populations that have declined precipitously for unclear reasons. The objective of this study was to determine whether Bd occurred historically in Missouri hellbender populations or is a relatively novel occurrence. Epidermal tissue was removed from 216 archived hellbenders collected from 7 Missouri streams between 1896 and 1994. Histological techniques and an immunoperoxidase stain were used to confirm historic occurrence of Bd infection in hellbenders from the North Fork of the White (1969, 1973, 1975), Meramec (1975, 1986), Big Piney (1986), and Current rivers (1988). Bd was not detected in hellbenders from the Niangua, Gasconade or Eleven Point rivers. The study detected no evidence for endemism of Bd in Missouri hellbender populations prior to 1969, despite the fact that nearly one third of the hellbenders sampled were collected earlier. Our findings are consistent with the hypothesis that Bd is a non-endemic pathogen in North America that was introduced in the second half of the twentieth century.

Distribution and prevalence of Cytauxzoon felis in bobcats (Lynx rufus), the natural reservoir, and other wild felids in thirteen states.

Cytauxzoon felis, a protozoan parasite of wild and domestic felids, is the causative agent of cytauxzoonosis in domestic and some exotic felids in the United States. The bobcat (Lynx rufus) is the natural reservoir for this parasite, but other felids such as Florida panthers (Puma concolor coryii) and domestic cats may maintain long-term parasitemias and serve as reservoirs. Experimentally, two tick species, Dermacentor variabilis and Amblyomma americanum, have demonstrated the ability to transmit C. felis. These two tick species have overlapping distributions throughout much of the southeastern United States. The objective of the current study was to determine the distribution and prevalence of C. felis in free-ranging bobcat populations from 13 states including California, Colorado, Florida, Georgia, Kansas, Kentucky, Missouri, North Carolina, North Dakota, Ohio, Oklahoma, South Carolina, and West Virginia. These states were selected because of differential vector presence; D. variabilis is present in each of these states except for the region of Colorado sampled and A. americanum is currently known to be present only in a subset of these states. Blood or spleen samples from 696 bobcats were tested for C. felis infection by a polymerase chain reaction (PCR) assay which targeted the first ribosomal internal transcribed spacer region (ITS-1). Significantly higher prevalences of C. felis were detected from Missouri (79%, n=39), North Carolina (63%, n=8), Oklahoma (60%, n=20), South Carolina (57%, n=7), Kentucky (55%, n=74), Florida (44%, n=45), and Kansas (27%, n=41) compared with Georgia (9%, n=159), North Dakota (2.4%, n=124), Ohio (0%, n=19), West Virginia (0%, n=37), California (0%, n=26), and Colorado (0%, n=67). In addition to bobcats, seven cougars (Puma concolor) from Georgia, Louisiana, and North Dakota and one serval (Leptailurus serval) from Louisiana were tested for C. felis. Only one cougar from Louisiana was PCR positive, which represents the first report of an infected cougar outside of the Florida panther population. These data also indicate that C. felis is present in North Dakota where infection has not been reported in domestic cats. Based on a nonparametric analysis, prevalence rates were significantly higher in states where there are established populations of A. americanum, which supports recent data on the experimental transmission of C. felis by A. americanum and the fact that domestic cat clinical cases are temporally associated with A. americanum activity. Collectively, these data confirm that bobcats are a common reservoir for C. felis and that A. americanum is likely an epidemiologically important vector.

A new 'view' of ecology and conservation through animal-borne video systems.

Over the past three decades, technological advances for monitoring wild animals have expanded the ability of ecologists to study animal behavior and space use. Currently, researchers are deploying animal-borne video and environmental data collection systems (AVEDs), which enable researchers to see what the animal sees in the field. AVEDs record fine-scale movements as well as features of the surrounding environment and thus provide essential context for understanding animal decisions and interactions with other individuals. These fine-scale data are often crucial for understanding potential conservation threats to species of concern. Here, we discuss the development and research potential offered by AVEDs. The benefits of AVEDs are greatest in hypothesis-driven studies that require a fine-scale perspective that other technologies cannot offer.