Aspects of the ecology and behaviour of the thick-tailed bushbaby Galago crassicaudatus
Date
2014-12-09
Authors
Bearder, Simon Kenneth
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Abstract
The extant prosimian primates, with the exception of some lemurs of
the Republic of Malagasy, are nocturnal arid secretive in their habits.
Several lines of evidence suggest that they have remained similar to
the basal orimate stock, but their study under natural conditions has,
until recent'y, been largely overlooked. Only eight prosimian species
remain on the Continent of Africa. Two relatively slow-moving lorises
(Perodicticus potto and Arctocebus calabarensis) and three active
galagos, or bushbabies (Euoticus elegantulus; Galago alleni and G. demidovii) are confined to the equatorial forest belt, while three other
galagos (Euoticus inustis ; G. crassicaudatus and G. senegalensis) show
adaptations for more open environments. A field study of G. crassicaudatus has been carried out in three distinct habitat types in southern Africa by means of direct observation with red light. Aspects of the ecology and behaviour of this species are presented and compared with those of other lorisoids and lemurs, particularly G. senegalensis, which is sympatric in some areas. In the absence of an adequate fossil record a consideration of species typical behaviour patterns and functional morphology leads to inferences concerning the probable behavioural and ecological condition of ancestral species, and conclusions regarding the separation and divergencies of recent forms. The morphological characteristics of G. crassicaudatus conform to the typical Galagine pattern of adaptation for active leaping progression but some features of their benaviour are reminiscent of members of the Lorisinae, with which they show a superficial similarity in their karyotype. It is concluded that the species directly ancestral to G. crassicaudatus
were smaller and more active leaping animals which underwent a secondary, behavioural, adaptation towards slower quadrupedal locomotion.
It is assumed that this was accompanied by an increase in body weight
which facilitated infant transport on the fur leading to closer contact
between mother and offspring and a better developed social group
structure. On the basis of this interpretation the behavioural similarities
with the Lorisinae are seen as the result of convergence and
not due to a close phylogenetic relationship.
Description
A Thesis Submitted to the Faculty of Science
University of the Witwatersrand, Johannesburg
for the Degree of Doctor of Philosophy
Johannesburg 1974