Search

Natural recolonization by large carnivores has rarely been documented. American black bears (Ursus americanus) recently (1988-present) recolonized portions of their former range in western Texas. We used mtDNA sequence data (n = 144 bears) from 7 populations of southwestern black bears in New Mexico, Texas, and northern Mexico to test predictions regarding metapopulation structure of the species in this region and the source of recolonization in western Texas. Six variable nucleotides were detected, resulting in 5 mtDNA haplotypes. Although within-site diversity of haplotypes (h) and nucleotides (π) was low, a high degree of genetic partitioning among sites was detected (&PhiST = 0.6301). Analyses pinpointed northern Mexico as the source of black bears for western Texas. Female-mediated gene flow is proceeding slowly in this system (Nfm = 0.4961 individuals/generation), but its occurrence was inferred via field observations. Nested clade analyses indicated that populations of bears in the Mexico-Texas region (area that encompasses mountain ranges within Nuevo Leon and Coahuila, Mexico, northward to smaller ranges located in the Trans-Pecos region of western Texas) were connected via restricted gene flow due to isolation by distance. Long-distance, colonization is the likely cause of extant geographical associations between New Mexican and Mexico-Texas populations. The naturally fragmented, xeric environment of the Chihuahuan Desert impedes colonization, but is not a complete barrier to this process. Conservation initiatives concerning recolonization by black bears within the Mexico-Texas mainland-island metapopulation should focus on preventing human-bear interactions and maintaining corridors for dispersal between the mainland populations in Mexico and the island populations in western Texas. [ABSTRACT FROM AUTHOR]

The upper Cahaba River in Alabama has experienced extensive urban development in its watershed in recent years. To assess the effects that these developments have had on the ichthyofauna, we compared data from samples made at 12 stations by other researchers prior to 1984 todata from samples collected by us at the same sites between 1995-97.Historical collections produced a total of 44 species, whereas recent samples produced 42. Two species, the blue shiner (Cyprinella caerulea) and the Alabama shad (Alosa alabamae), have been extirpated fromthis system. Relative abundances of the various taxa in recent samples correlated poorly with those of historical samples, indicating that the compositions of the ichthyological communities have changed. Disturbancetolerant cyprinids (minnows) have generally increased in percent relative abundance (PRA) in recent collections, whereas the disturbance-sensitive cyprinids have generally decreased. The PRA of percids (darters) has decreased in recent collections, especially the disturbance-sensitive species such as the coal darter (Percina brevicauda) and the greenbreast darter (Etheostoma jordani). The ichthyofaunaldiversity, as measured by several indices, has decreased in recent samples. These changes in the fish populations have occurred concurrently with extensive urbanization and resultant degradation of water and habitat that has taken place in the watershed over the last 20 years. [ABSTRACT FROM AUTHOR]

Feline leukemia virus (FeLV) is a gammaretrovirus with horizontally transmitted and endogenous forms. Domestic cats are the primary reservoir species, but FeLV outbreaks in endangered Florida panthers and Iberian lynxes have resulted in mortalities. To assess prevalence and interspecific/intraspecific transmission, we conducted an extensive survey and phylogenetic analysis of FeLV infection in free-ranging pumas ( n  = 641) and bobcats ( n  = 212) and shelter domestic cats ( n  = 304). Samples were collected from coincident habitats across the United States between 1985 and 2018. FeLV infection was detected in 3.12% of the puma samples, 0.47% of the bobcat samples, and 6.25% of the domestic cat samples analyzed. Puma prevalence varied by location, with Florida having the highest rate of infection. FeLV env sequences revealed variation among isolates, and we identified two distinct clades. Both progressive and regressive infections were identified in cats and pumas. Based on the time and location of sampling and phylogenetic analysis, we inferred 3 spillover events between domestic cats and pumas; 3 puma-to-puma transmissions in Florida were inferred. An additional 14 infections in pumas likely represented spillover events following contact with reservoir host domestic cat populations. Our data provide evidence that FeLV transmission from domestic cats to pumas occurs widely across the United States, and puma-to-puma transmission may occur in genetically and geographically constrained populations. IMPORTANCE Feline leukemia virus (FeLV) is a retrovirus that primarily affects domestic cats. Close interactions with domestic cats, including predation, can lead to the interspecific transmission of the virus to pumas, bobcats, or other feline species. Some infected individuals develop progressive infections, which are associated with clinical signs of disease and can result in mortality. Therefore, outbreaks of FeLV in wildlife, including the North American puma and the endangered Florida panther, are of high conservation concern. This work provides a greater understanding of the dynamics of the transmission of FeLV between domestic cats and wild felids and presents evidence of multiple spillover events and infections in all sampled populations. These findings highlight the concern for pathogen spillover from domestic animals to wildlife but also identify an opportunity to understand viral evolution following cross-species transmissions more broadly.