BakerCScottFisheriesWildlifeStrongMaternalFidelity.pdf
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Abstract
We quantified the relative influence of maternal fidelity to feeding grounds and natal
fidelity to breeding grounds on the population structure of humpback whales Megaptera novae-angliae based on an ocean-wide survey of mitochondrial (mt) DNA diversity in the North Pacific.
For 2193 biopsy samples collected from whales in 10 feeding regions and 8 breeding regions during
the winter and summer of 2004 to 2006, we first used microsatellite genotyping (average,
9.5 loci) to identify replicate samples. From sequences of the mtDNA control region (500 bp) we
identified 28 unique haplotypes from 30 variable sites. Haplotype frequencies differed markedly
among feeding regions (overall F[subscript ST] = 0.121, Φ[subscript ST] = 0.178, p < 0.0001), supporting previous evidence
of strong maternal fidelity. Haplotype frequencies also differed markedly among breeding regions
(overall F[subscript ST] = 0.093, Φ[subscript ST] = 0.106, p < 0.0001), providing evidence of strong natal fidelity. Although
sex-biased dispersal was not evident, differentiation of microsatellite allele frequencies was weak
compared to differentiation of mtDNA haplotypes, suggesting male-biased gene flow. Feeding
and breeding regions showed significant differences in haplotype frequencies, even for regions
known to be strongly connected by patterns of individual migration. Thus, the influence of migratory
fidelity seems to operate somewhat independently on feeding and breeding grounds over an
evolutionary time scale. This results in a complex population structure and the potential to define
multiple units to conserve in either seasonal habitat.Keywords: mtDNA, Genetic management units, Microsatellite genotypes, Migratio