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- Karczmarski, Leszek, et al.
(författare)
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Spinner dolphins in a remote Hawaiian atoll : social grouping and population structure
- 2005
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Ingår i: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 16:4, s. 675-685
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Tidskriftsartikel (refereegranskat)abstract
- Spinner dolphins (Stenella longirostris) commonly use inshore island and atoll habitats for daytime rest and social interactions and forage over deep waters at night. In Hawaii, they occur throughout the archipelago. We applied photoidentification mark-recapture techniques to study the population structure of spinner dolphins associated with remote Midway Atoll, far-western Hawaii. At Midway, spinner dolphins live in stable bisexually bonded societies of long-term associates, with strong geographic fidelity, no obvious fission-fusion, and limited contacts with other populations. Their large cohesive groups change little over time and are behaviorally/socially discrete from other spinner dolphin groups. This social pattern differs considerably from the fluid fission-fusion model proposed previously for spinner dolphins associated with a large island habitat in the main Hawaiian Archipelago. These differences correspond to geographic separation and habitat variation. While in the main islands there are several daytime resting places available at each island habitat; in far-western Hawaii, areas of suitable habitat are limited and separated by large stretches of open pelagic waters with potentially high risk of shark predation. We hypothesize that with deepwater food resources in close proximity and other atolls relatively far away for easy (day-to-day) access, it is energetically more beneficial in the remote Hawaiian atolls to remain “at home” than to travel to other atolls, so there is stability instead of variability; there is no fission-fusion effect. Thus, the geographic isolation and small size of remote atolls trigger a process in which the fluidity of the fission-fusion spinner dolphin society is replaced with long-term group fidelity and social stability.
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| 2. |
- Mendez, Martin, et al.
(författare)
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Integrating multiple lines of evidence to better understand the evolutionary divergence of humpback dolphins along their entire distribution range : a new dolphin species in Australian waters?
- 2013
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Ingår i: Molecular Ecology. - : Wiley. - 0962-1083 .- 1365-294X. ; 22:23, s. 5936-5948
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Tidskriftsartikel (refereegranskat)abstract
- The conservation of humpback dolphins, distributed in coastal waters of the Indo-West Pacific and eastern Atlantic Oceans, has been hindered by a lack of understanding about the number of species in the genus (Sousa) and their population structure. To address this issue, we present a combined analysis of genetic and morphologic data collected from beach-cast, remote-biopsied and museum specimens from throughout the known Sousa range. We extracted genetic sequence data from 235 samples from extant populations and explored the mitochondrial control region and four nuclear introns through phylogenetic, population-level and population aggregation frameworks. In addition, 180 cranial specimens from the same geographical regions allowed comparisons of 24 morphological characters through multivariate analyses. The genetic and morphological data showed significant and concordant patterns of geographical segregation, which are typical for the kind of demographic isolation displayed by species units, across the Sousa genus distribution range. Based on our combined genetic and morphological analyses, there is convincing evidence for at least four species within the genus (S.teuszii in the Atlantic off West Africa, S.plumbea in the central and western Indian Ocean, S.chinensis in the eastern Indian and West Pacific Oceans, and a new as-yet-unnamed species off northern Australia).
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