Hybridization between sympatric hammerhead sharks in the western North Atlantic Ocean. (26th April 2019)

• Record Type: Journal Article
• Authors: Barker, Amanda M.; Adams, Douglas H.; Driggers, William B.; Frazier, Bryan S.; Portnoy, David S.
• Is Part Of: Biology letters. Volume 15:Number 4(2019)
• Publication Date: 2019-04-26
• Subjects: cryptic species -- elasmobranch -- endangered species -- introgression -- Sphyrnidae; Biology -- Periodicals; 570.5
• DOI: 10.1098/rsbl.2019.0004
• Languages: English
• ISSNs: 1744-9561

Abstract

Abstract : Hybridization between closely related species has been documented across a wide range of taxa but has not been well studied in elasmobranchs. Hammerhead sharks have drawn global conservation concern because they experience some of the highest mortality rates among sharks when interacting with fisheries. Here we report on the detection of hybrids between the globally distributed scalloped hammerhead ( Sphyrna lewini ) and recently described Carolina hammerhead ( S. gilberti ) which are only known from the western Atlantic Ocean. Using a genomics approach, 10 first-generation hybrids and 15–17 backcrosses were detected from 554 individuals. The identification of backcrosses demonstrates hybrids are viable, and all backcrosses but one involved a scalloped hammerhead. All hybrids but one possessed Carolina hammerhead mtDNA, indicating sex-biased gene flow between species. Repeated hybridization and backcrossing with scalloped hammerheads could lead to the loss of endemic Carolina hammerheads.