Generalist dispersal and gene flow of an endangered keystone specialist (Dipodomys ingens)

Movement ecology and dispersal capabilities inherently drive genetic structure across landscapes. Through understanding dispersal and gene flow of giant kangaroo rats (Dipodomys ingens), conservation efforts can be focused, and we can further understand how genetic structure persists in this highly endemic small mammal. Here, we genetically identify parent–offspring and sibship relationships among 239 giant kangaroo rats using 15 microsatellites in the northern part of the species range and describe the individual genetic-spatial variation using a Moran eigenvector map (MEM). We further employ two landscape genetic analyses (isolation by resistance [IBR] and least cost paths [LCPs]) and two individual-based genetic metrics (Dps and a codominant marker distance from GenAlEx) to determine landscape factors (precipitation, slope, vegetation community, and roads) that influence gene flow. We found 19 pairs of related individuals, of which 18 were less than 250 m apart, but one sibling pair was 5.52 km apart, suggesting greater dispersal capabilities than previously noted. We found hierarchal spatial genetic structure using a MEM, with 3–4 genetically similar regions and two genetically similar subregions. Finally, we found low correlative strength between landscape features and gene flow. IBR consistently outperformed LCPs, and there was evidence that regions with 250–350 mm of precipitation and slope ≤ 5° promoted connectivity. We recommend that managers focus on habitat protection rather than corridor maintenance, with the caveat that anthropogenic factors were minimally considered in this study.

DISTRIBUTION OF THE ENDANGERED GIANT KANGAROO RAT, DIPODOMYS INGENS, ON THE NAVAL PETROLEUM RESERVES, CALIFORNIA

ABSTRACTBurrows of the endangered giant kangaroorat, Dipodomys ingens, were found on the U.S. Department of Energy’s Naval Petroleum Reserves in Kern County, California. The majority of burrows (63%) were found in areas of low relief (4.3 ± 0.5°, n=32) on valley floors but 28% were unexpectedly found on low relief areas (6.4 ± 0.8°, n=39) in the uplands. Burrows were not distributed in proportion to the arealextend of the soil series, but were concentrated in deep alluvial sandy loams. Well pads were the most frequently observed (73% of 211) humandisturbance in the vicinity of burrows, but they were the most distant (150± 61m, n=150). Dirt roads were observed closer to burrows (50 ± 10 m, n=28) but less frequently (4%). Only 8 burrows were found in the vicinity of proposed petroleum developments but no projects had to me modified to avoid negatively affecting the species.RESUMEN.—Madrigueras de las ratas canguro, Dipodomys ingens, a riesgo de extinsioń, fueron localizadas en el Departmento de Energía, Reservas Navales de Petroleo en el Condado de Kern, California. La mayoria de las madrigueras (63%) se encuentran en arias de bajo relieve (4.3 ± 0.5°, n=32) en valles, pero el 28% fueron inesperadamente localizadas en arias de bajo relieve (6.4 ± 0.8°, n=39) en terrenos elevados. Las madriguera no se distribuyen en proporcion de acuerdo a la variedad de terrenos, sino concentradas en las lomas aluviales arenosas. Los disturbios humanos observados con mas frecuencia (73% of 211) en la vecindad de las madrigueras son los almohadillas de pozos petroleros pero se encontran amayor distancia (150 ± 61m, n=150). Caminos de tierra fueron encontrados cerca de las madrigueras (50 ± 10m, n=28) pero con menos frecuenciz (4%). Unicamente ocho madrigueras fueron localizadas en la vecindad de los propuestos desarroyos petroleros pero ningun proyecto se debe modificar para evitar efectos negativos que pueden afectar a la especie.