PARENT SESSION
Organized Oral Session 28: Ecological processes important in the responses of bird populations to environmental change driven by agriculture
Organizer(s): K Norris, E Chambers, and J Vickery
Wednesday, August 10, 8:00 AM - 11:30 AM, Meeting Room 511a, Level 5, Palais des congrès de Montréal

Historical change in dispersal ability and developmental stability predicts current biodiversity impact of forest fragmentation in a Kenyan agricultural landscape.

Lens, Luc ^*,1, ¹ Ghent University, Ghent, Belgium

ABSTRACT- Predicting effects of habitat changes, such as forest fragmentation and degradation due to anthropogenic activity, on species viability is a major goal in conservation biology. Yet, high between-species variability in demographic and genetic responses often hampers general conclusions. To understand which species are most affected by forest fragmentation, we combined data on historical gene flow, genetic bottlenecks and migration-drift disequilibria with current capture-recapture data of five sympatric bird species inhabiting indigenous forest remnants embedded within a Kenyan agricultural landscape. Historical (pre-fragmentation) dispersal rates were estimated from microsatellite-based F_ST-values. Current (post-fragmentation) rates were estimated from multi-strata mark-recapture models. Three species showed moderate to high levels of current as well as historical dispersal. One of the two remaining species with low levels of current dispersal showed moderate historical dispersal and thus suffered the strongest decrease in mobility. This species further showed F_ST-disequilibrium, lowest mean numbers of alleles and allelic richness, and recent bottlenecks in all remnant populations. Observed and expected levels of heterozygosity were comparable to those found in various endangered bird species. We conclude that the genetic signature of recent habitat fragmentation can differ markedly even between sympatric bird species, and is linked with differential changes in important ecological processes such as mobility. Consequently, genetic impacts of future environmental changes may not be predictable by assessing current mobility alone.

Key words: dispersal, developmental stability, fragmentation, Kenya