Ecology, genetics and conservation of partial migration in ungulates

Friday seminar by Mark Hebblewhite (NB: Note the time and venue)

Abstract

 

Partial migration is widespread in ungulates, yet few studies have tested for mechanisms responsible for its maintenance, despite recent studies showing declining migration in ungulates because of human activity. Three main hypotheses have been proposed for the maintenance of partial migration in; 1) facultative switching between strategies, 2) genetic determinism, and 3) demographic fitness balancing at the population level. These different mechanisms have different conservation implications in populations with declining migrants. Here, I review 3 case studies of partial migration in ungulates to understand partial migration mechanisms and evaluate effectiveness of conservation strategies to conserve migrants. I first test for demographic fitness balancing between migrants and residents in a partially migratory elk population. Partial migration for elk seems best explained by demographic fitness balancing at the population level because we found little evidence for switching and no genetic differences between elk. In this system, human-induced refugia increased fitness for resident elk despite foregoing benefits to migration, and would require fine-scale management actions to reverse migrant declines. In the second case study of partially migratory woodland caribou, we used a combination of demographic, behavioral and genetic methods to investigate the differential impacts of human activity on migrant and residents. We found migrant caribou experienced the lowest survival rates, and that migration itself was correlated to the mitochondrial haplotype of caribou, evidence for some genetic basis for migration. Only large-scale conservation strategies that conserved the fitness landscape of migrants would sustain migratory woodland caribou. Finally, we evaluated differences in spatial resource use for migratory and resident Serengeti wildebeest, one of the least appreciated partially migratory systems in the world. Under recent threats of road building in the Serengeti, migrant wildebeest would be expected to suffer more than residents, although the mechanisms responsible for maintenance of partial migration are unknown in this system. In conclusion, understanding the mechanisms of partial migration is necessary to counter changes or loss of migration in ungulate populations, and will vary across systems.

Mark Hebblewhite
Assistant Professor of Ungulate Habitat Ecology
Department of Ecosystem and Conservation Sciences
College of Forestry and Conservation
University of Montana
Missoula, MT 59812


 

Published Feb. 3, 2012 3:47 PM - Last modified Oct. 23, 2013 11:25 AM