Melding kin structure and demography to elucidate source and sink habitats in fragmented landscapes

Abstract

Citation: Beasley, J. C., G. Dharmarajan, and O. E. Rhodes, Jr. 2015. Melding kin structure and demography to elucidate source and sink habitats in fragmented landscapes. Ecosphere 6(4):61. http://dx.doi.org/10.1890/ES14-00274.1Abstract. The source-sink model undoubtedly is one of the most established paradigms for associating variance in population dynamics with heterogeneity in habitat quality. However, despite extensive theoretical support by the scientific community, the majority of studies seeking empirical validation for this model have lacked sufficient data to distinguish source and sink habitats, particularly for large or secretive mammals. Using relatively long-term mark-recapture and genetic data for a generalist mesopredator within a fragmented agricultural ecosystem, we show that use of a two-stage approach incorporating both genetic and demographic data can be a powerful tool for evaluating the population structure of organisms occupying complex ecological systems. We further demonstrate that a strong concordance exists between demographic attributes and underlying genetic expectations, suggesting evaluation of fine-scale genetic patterns alone may provide valuable insights into the population dynamics of species. These data have important implications for advancing our ability to quantify heterogeneity in population stability, particularly for large or imperiled species where sufficient demographic data cannot be obtained to parameterize traditional source-sink models.

Evaluating the influence of life‐history characteristics on genetic structure: a comparison of small mammals inhabiting complex agricultural landscapes

“…The UWB has been largely converted to agriculture and has been subject of extensive study to assess the ecological effects of land conversion on a variety of vertebrate species Swihart 1998, 2000;Goheen et al 2003;Swihart et al 2003; Moore and Swihart 2005;Dharmarajan et al 2009;Beatty et al 2012;Anderson et al 2015). These studies have confirmed that both landscape heterogeneity and life-history traits, particularly ecological specialization, influence patterns in occupancy and abundance (Nupp and Swihart 1998;Swihart et al 2003;Moore and Swihart 2005;Beasley et al 2015). In rodents, for example, dependence on forest largely predicted if a species was sensitive to habitat fragmentation, whereas generalist species tended to benefit from agriculture regardless of body size Swihart 1998, 2000;Swihart et al 2003).…”

“…; Moore and Swihart ; Beasley et al. ). In rodents, for example, dependence on forest largely predicted if a species was sensitive to habitat fragmentation, whereas generalist species tended to benefit from agriculture regardless of body size (Nupp and Swihart , ; Swihart et al.…”

Raccoon spatial ecology in the rural southeastern United States

“…Raccoons (Procyon lotor) are generalist mesopredators that occupy diverse native habitats including pine forests, hardwood forests, prairies, and wetlands, in addition to anthropogenic habitats such as agricultural and urban areas [7][8][9]. Across this spectrum of habitats, raccoon home range sizes may vary widely in accordance with the abundance and availability of resources such as food, free water, and denning habitat [9][10][11][12]. In urban and agricultural habitats with high resource concentrations, raccoons need to travel less widely to meet resource requirements, resulting in smaller home ranges and greater population densities [7,9,10,[13][14][15].…”

“…Raccoons likely have smaller home ranges in resource abundant habitats such as bottomland hardwoods and riparian forests, which contain ample free water and large diameter trees for denning [23][24][25]. Upland pine forests, on the other hand, tend to have less suitable trees for denning, less water, and decreased availability of soft mast, an important food for raccoons in natural areas, likely leading to lower density raccoon populations with larger home ranges [8,11,23,24]. Male raccoons usually have larger home ranges than females due to increased resource requirements and their attempts to overlap with the home ranges of multiple females to maximize mating opportunities [7,24,26].…”