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1.1. Overview
1. General Introduction
Chapter One: General Introduction
Pryor & Norris (1991) noted several misconceptions concerning dolphin research.
These misconceptions, some of which have persisted to the present day, include the
assumption that wild dolphins are so inaccessible that it is “not worthwhile” to study
them, and the assumption that the social behaviour and organisation of all dolphin
species is similar to Tursiops. However, the development of novel methods, such as
photo-identification, telemetry, biopsy sampling and molecular markers, and the
recent improvements in data analyses provide an opportunity to dismiss these
misconceptions.
It is true that a large proportion of dolphin studies have concerned bottlenose
dolphins (Genera Tursiops, composed of two species, T. truncatus and T. aduncus).
Around the world, bottlenose dolphins form small resident coastal populations
(Connor et al. 2000b), generally living in small groups, thus making them easier to
study than most other dolphin species. Tursiops is one of only two genera of
cetaceans in which some populations have been the subject of studies long enough
to gather information over more than one generation (see review by Mann et al.
2000). Only one other species of dolphin has benefited from a similar kind of
attention; the killer whale (Orcinus orca) from eastern North Pacific (e.g., Bigg et al.
1990, Baird 2000). Other long term studies on other dolphin species have been or
are currently being undertaken (e.g., Norris et al. 1994), but none have reached the
level of detail obtained on populations of bottlenose dolphins and killer whales.
Considering that more than 30 species of dolphins are currently recognised
worldwide (Rice 1998), it is evident that our knowledge on the ecology and status of
this taxonomic family remains very limited.
In this thesis, I used genetic and observational data to investigate the population
structure and social system of four species of dolphins which have not benefited from
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