Original Research

Behavior Genetics

, Volume 42, Issue 2, pp 332-343

First online:

Can Genetic Differences Explain Vocal Dialect Variation in Sperm Whales, Physeter macrocephalus?

  • Luke RendellAffiliated withCentre for Social Learning and Cognitive Evolution, School of Biology, University of St Andrews Email author 
  • , Sarah L. MesnickAffiliated withSouthwest Fisheries Science Center, National Marine Fisheries Service, NOAACenter for Marine Biodiversity and Conservation, Scripps Institution of Oceanography University of California
  • , Merel L. DaleboutAffiliated withDepartment of Biology, Dalhousie UniversitySchool of Biological, Earth and Environmental Sciences, University of New South Wales
  • , Jessica BurtenshawAffiliated withSouthwest Fisheries Science Center, National Marine Fisheries Service, NOAACenter for Marine Biodiversity and Conservation, Scripps Institution of Oceanography University of California
  • , Hal WhiteheadAffiliated withDepartment of Biology, Dalhousie University

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Abstract

Sperm whale social groups can be assigned to vocal clans based on their production of codas, short stereotyped patterns of clicks. It is currently unclear whether genetic variation could account for these behavioural differences. We studied mitochondrial DNA (mtDNA) variation among sympatric vocal clans in the Pacific Ocean, using sequences extracted from sloughed skin samples. We sampled 194 individuals from 30 social groups belonging to one of three vocal clans. As in previous studies of sperm whales, mtDNA control region diversity was low (π = 0.003), with just 14 haplotypes present in our sample. Both hierarchical AMOVAs and partial Mantel tests showed that vocal clan was a more important factor in matrilineal population genetic structure than geography, even though our sampling spanned thousands of kilometres. The variance component attributed to vocal dialects (7.7%) was an order of magnitude higher than those previously reported in birds, while the variance component attributed to geographic area was negligible. Despite this, the two most common haplotypes were present in significant quantities in each clan, meaning that variation in the control region cannot account for behavioural variation between clans, and instead parallels the situation in humans where parent-offspring transmission of language variation has resulted in correlations with neutral genes. Our results also raise questions for the management of sperm whale populations, which has traditionally been based on dividing populations into geographic ‘stocks’, suggesting that culturally-defined vocal clans may be more appropriate management units.

Keywords

Sperm whale Vocal dialect Cultural transmission Genetic population structure