9th International Deer Biology Congress

AUTHORS: Lisa I. Muller, University of Tennessee, Department of Forestry, Wildlife and Fisheries; Jennifer L. Murrow, University of Maryland, Environmental Science and Policy Program; Jason L. Lupardus, National Wild Turkey Federation; Joseph D. Clark, US Geological Survey, Southern Appalachian Research Branch, University of Tennessee; Bradley F. Miller, Tennessee Wildlife Resources Agency

ABSTRACT: Translocation of organisms from one site to another site is a commonly used tool to restore populations, species, or even ecosystem function. However, many of these reintroductions have not been successful in establishing viable populations (reviewed in [1]). Batson et al. [2] reviewed the available literature to develop 30 tactics to facilitate translocation success including maximizing genetic diversity and selection of organisms with similar genetic characteristics to the original stock (or adapted to the original range). Kelly and Phillips [3] even suggested using targeted gene flow and moving pre-adapted individuals to new locations to make sure favorable traits promote restoration success. These favorable adaptations may be for disease resistance or variations better suited to different climates. Also low genetic diversity may lead to inbreeding depression and a decrease in immunocompetence [1]. Therefore, genetic makeup may affect population growth and persistence of the reintroduced species. Given the significance of the source population for successful reintroduction, we should give high importance to genetic considerations.
Recent research has revealed the presence of so-called cryptic metapopulations (i.e., a spatially continuous distribution of organisms exhibiting metapopulation-like behaviors) in giraffes (Giraffa camelopardalis, [4]), and red deer (Cervus elaphus, [5, 6]). We have identified this phenomenon in 2 reintroduced populations of a large and highly mobile mammal, elk (Cervus elaphus) in Tennessee and North Carolina, which could have significant implications for conservation of elk but also all other reintroduced species [7].
Elk from Elk Island National Park (EINP), which is located 45 km northeast of Edmonton, Alberta, Canada have been used for restoration projects in Ontario, Canada, Kentucky at Land Between the Lakes (LBL), Cumberland Mountains, Tennessee, and Great Smoky Mountains National Park in North Carolina. What is unique about EINP elk is that there are 2 genetically distinct populations because animals from the north side have been isolated for over 100 years and the south side for over 50 years by a 2.2-m high fence. EINP (196 km2) was established in 1906 to preserve a small herd of 75 elk and has many native herbivores and few large predators [8]. EINP is bisected by a major highway (Highway 16) and fence which was first established on the north side in 1907. Therefore, about 15 elk generation times have occurred which have brought about distinct genetic structuring between the north and south sides of the park. Elk are trapped on both sides of the road and brought to a central handling facility where they are mixed together, marked and processed for shipment to restoration sites. Given the separation of the 2 populations at EINP, we are interested in how genetic structuring affects reintroduction efforts when these animals are transported to new habitats.
What We Know about Genetic Structure at EINP: At the time of capture at EINP or LBL (originally from EINP), we were able to obtain blood or hair from 220 elk that were later translocated to GSMNP and TNCM [7]. Wildlife Genetics International (WGI; http://www.wildlifegenetics.ca/) analyzed 16 microsatellite markers commonly used in game-farmed elk. We used the program STRUCTURE [9], which provides a Bayesian clustering algorithm to assign genetic structure without any prior assumption of group membership. We found 92.7% (n=220) strongly assigned to one of the 2 populations. Only 7.3% (n=16) of the population had indications of mixing between the 2 clusters. These distinct clusters are related to the road at the source site of EINP [7].
Continued Elk Population Structure after Translocation from EINP: We continue to observe population structure in LBL, TNCM and GSMNP, with few admixtures, despite overlapping ranges and potential breeding opportunities between the 2 genetic groupings 11+ years after reintroduction. This structure means the effective population sizes of these reintroduced populations are much smaller than originally thought, which could affect population persistence. The genetic consequences of smaller effective population sizes than presumed could lead to inbreeding and other deleterious genetic effects. More research needs to evaluate the effects of this genetic structure and identify possible mechanisms for continued reproductive isolation. We need to understand effects of cryptic population structuring on reintroductions or restoration of wildlife species.