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Dusky dolphins of Kaikoura, New Zealand: behavioral effects of genetic sampling and analysis of population structure
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Seasonal differences in group size, behavior, icrographics. distribution, and coloration patterns of dusky dolphins (Lacenorhynchus obscures) in Kaikoura, New Zealand, have led researchers to question whether "winter'' and "summer'' groups are temporally and behaviorally segregated into genetically distinct populations. Exfoliated skin samples were collected in Kaikoura from July 1997 to May 1998 for genetic analysis of 40 "winter'' and 40 "summer'' individuals via skin swab. A 473 base pair section of the mitochondrion DNA control region was amplified and sequenced for the 80 samples. Nucleotide and haplotype diversity were 0.16 and 0.98, respectively. AMOVA and phylogenetie analyses indicate "winter'' and "summer'' groups are not subdivided with respect to maternal lineages. Lack of subdivision between seasonal populations is further supported by: (1) demographic patterns determined from mismatch distribution analysis suggest New Zealand dusky dolphins underwent a population expansion in the Pleistocene; (2) current levels of diversity suggest the long-term effective population size has been large', (3) preliminary analysis of photo-identification data indicate individuals are present in Kaikoura both winter and summer; (4) comparison of 80 samples from Kaikoura to eight beach-east samples from locations throughout New Zealand reveal shared haplotypes between regions. Behavioral responses to sampling were recorded for 315 contacts and 48 controls. The number of pro-and pest-contact joyriders and sample time were used as indicators of group-level response to sampling. The behavioral state of dolphins prior to sampling or time of day did not affect responses to sampling. Small groups were found to be more sensitive to sampling. Dolphin groups appeared to habituate to sampling activities after the first hour spent sampling. Responses to sampling were mild with 18% showing no response to contact. The most frequent response was to move right or left of the bow. Thirty-three percent of dolphins returned to the bow within 10.8  0.73 seconds. There was no significant difference between proportion of responses between treatment and control groups, suggesting a proportion of responses to sampling can be explained by normal behavior in the presence of a vessel.
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Includes bibliographical references (leaves 75-88).
Harlin, April Dawn (1999). Dusky dolphins of Kaikoura, New Zealand: behavioral effects of genetic sampling and analysis of population structure. Master's thesis, Texas A&M University. Available electronically from
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