Foraging segregation and genetic divergence between geographically proximate colonies of a highly mobile seabird


Wiley, Anne

Welch, Andreanna

Ostrom, Peggy

James, Helen

Stricker, Craig

Fleischer, Robert

Gandhi, Hasand

Adams, Josh

Ainley, David

Duvall, Fern

Holmes, Nick

Du, Darcy

Judge, Seth

Penniman, Jay

Swindle, Keith

Journal or Book Title: Oecologia

Keywords: gene flow; niche segregation; population ecology; salt load; stable isotopes

Volume/Issue: 168(1)

Page Number(s): 119-130

Year Published: 2012


DOI: 10.1007/s00442-011-2085-y

Type of Publication: Journal Article


Foraging segregation may play an important role in the maintenance of animal diversity, and is a proposed mechanism for promoting genetic divergence within seabird species. However, little information exists regarding its presence among seabird populations. We investigated genetic and foraging divergence between two colonies of endangered Hawaiian petrels (Pterodroma sandwichensis) nesting on the islands of Hawaii and Kauai using the mitochondrial Cytochrome b gene and carbon nitrogen and hydrogen isotope values (δ13C, δ15N and δD, respectively) of feathers. Genetic analyses revealed strong differentiation between colonies on Hawaii and Kauai, with ΦST = 0.50 (p < 0.0001). Coalescent-based analyses gave estimates of <1 migration event per 1,000 generations. Hatch-year birds from Kauai had significantly lower δ13C and δ15N values than those from Hawaii. This is consistent with Kauai birds provisioning chicks with prey derived from near or north of the Hawaiian Islands, and Hawaii birds provisioning young with prey from regions of the equatorial Pacific characterized by elevated δ15N values at the food web base. δ15N values of Kauai and Hawaii adults differed significantly, indicating additional foraging segregation during molt. Feather δD varied from -69 to 53%. This variation cannot be related solely to an isotopically homogeneous ocean water source or evaporative water loss. Instead, we propose the involvement of salt gland excretion. Our data demonstrate the presence of foraging segregation between proximately nesting seabird populations, despite high species mobility. This ecological diversity may facilitate population coexistence, and its preservation should be a focus of conservation strategies.