Mature female sperm whales (Physeter macrocephalus) live in socially cohesive groups of 10-30, which include immature animals of both sexes, and within which there is communal care of the young. We examined kinship in such groups using analyses of microsatellite DNA, mitochondrial DNA sequence, and sex-linked markers on samples of sloughed skin collected noninvasively from animals in three groups off the coast of Ecuador. Social groups were defined through photographic identification of individuals. Each group contained about 26 members, mostly female (79%6).Relatedness was greater within groups, as compared to between groups. Particular mitochondrial haplotypes were characteristic of groups, but all groups contained more than one haplotype. The data are generally consistent with each group being comprised of several matrilines from which males disperse at about the age of 6 years. There are indications of paternal relatedness among grouped individuals with different mitochondrial haplotypes, suggesting long-term associations between different matrilines.

No abstract

Samples of sperm whale skin, useful for modern molecular analyses of DNA, can be obtained from living animals either by collecting skin sloughed naturally by the whales, or by using biopsy darts fired from crossbows or compound bows. Sloughed skin was found frequently in warm waters, and particular samples could often be linked to photographs which enabled individuals to be identified. However, sloughed skin seemed less available at higher latitudes. Two types of darts were found to collect skin but collected samples were very small (<4 mm2) and insufficient for repeated DNA fingerprinting analyses. Sperm whales always reacted to darting by “startling” and showing changes of behavior over the next few minutes, but we found no indications of longer‐term effects. In warm water studies, collection of sloughed skin seems to be generally effective, but for samples of sperm whale tissue at high latitudes modifications could probably be made to either of the darts in order to obtain larger‐sized samples.

We sequenced a 152 base pair fragment of the sperm whale (Physeter macrocephalus) SRY gene in order to obtain species-specific primers for determination of sex by the polymerase chain reaction (PCR). Sequence identity between the sperm whale SRY fragment and the homologous motif in a variety of other mammals was high, though generally higher with ungulates (~88%) than with the human (85%), rabbit (80%), mouse (75%), or marsupial mouse (66%). When primers based on the sperm whale sequence were employed for PCR, a single product was amplified from male sperm whale DNA, whereas no product was amplified from female DNA. This SRY fragment was also amplified from other cetacean male DNA, but not from human DNA. Thus, under appropriate PCR conditions, the use of the cetacean-specific primers in an assay to determine sex eliminates the possibility of false results owing to contamination by human DNA. To confirm the results of the SRY analysis we sexed the same individual sperm whales by restriction analysis of PCR-amplified fragments from the ZFY and ZFX genes, using universal primers and methods previously reported to work for other cetacean species.

No abstract