Widespread gene flow between oceans in a pelagic seabird species complex

Area of Science:

• Conservation Biology
• Evolutionary Biology
• Ornithology

Background:

• Global gene flow impacts genetic diversity in species and populations.
• Interspecies gene flow and hybridization are understudied, especially in seabirds.
• Round Island, Indian Ocean, is a known site for mixed-species petrel hybridization.

Purpose of the Study:

• To investigate the possibility of between-species hybridization occurring outside the Indian Ocean.
• To assess global-scale gene flow and dispersal in closely related Procellariiform species.
• To understand the prevalence of interspecific hybridization in Pterodroma petrels.

Main Methods:

• Microsatellite genotyping of petrel populations.
• Analysis of migration rates using Bayesass software.
• Geolocation tracking of Round Island petrels.
• Population structure analysis using STRUCTURE software.

Main Results:

• Dispersal and gene flow spanning three oceans were demonstrated between Atlantic and Pacific petrel species.
• Unidirectional movement of petrels from the Atlantic and Pacific into the Indian Ocean was observed.
• Gene flow between Atlantic and Pacific species was detected, with potential three-way hybrids identified outside the Indian Ocean.
• Geolocation tracking revealed Round Island petrels traveling to both the Atlantic and Pacific oceans.

Conclusions:

• Interspecific hybrids in Pterodroma petrels are more common than previously assumed.
• Widespread migration and hybridization occur on a global scale in these seabirds.
• Conservation strategies for threatened seabirds must consider extensive migration and hybridization.