Non-geographically based population structure of south pacific sperm whales: Dialects, fluke-markings and genetics

1. This study addresses the issue of structure in sperm whale (Physeter macrocephalus Linnaeus) populations and whether it is geographically based. 2. During a survey around the South Pacific Ocean, we collected sloughed skin for genetic analyses, recorded coda vocalizations, and photographed fluke markings. 3. Groups of female and immature sperm whales had characteristic mitochondriai haplotypes, coda repertoires, and fluke-mark patterns, but there was no clear geographical structure in any of these attributes. 4. However, similarities of coda repertoire and mitochondrial haplotype distribution were significantly correlated among pairs of groups in a manner that was not geographically based. There was also a significant canonical correlation coefficient between coda repertoire and fluke-mark patterns. 5. These results suggest that attributes (such as vocal repertoire and techniques of predator defence) which are acquired matrilineally, and probably culturally, are conserved during the fission and dispersal of groups.