The dispersalforaging maladaptation hypothesis

The regional elephant populations of Africa have fluctuated considerably since the seventeenth century as a result of an upsurge or abatement in ivory poaching (chapter 8). By the end of the nineteenth century, the elephant populations of West Africa, southern Africa (south of the Zambezi River), and East Africa had been largely wiped out. These regions suffered greatly because of their relative accessibility to trade routes out of the continent.

Hugo Jachmann and Richard Bell proposed that the Central African elephants, which were not affected to the same extent, dispersed into southern and eastern Africa as the populations there depleted. The moist forest-dwelling

Figure 6.6

The relationship between density of Acacia xanthophloea trees and soil salinity in Amboseli, Kenya. A sharp inflection point at about 7-8 ECe divides sparse from dense stands when plotted on a normal scale. (From Western and van Praet 1973. Reprinted by permission from Nature, 241, 104-106. Copyright 1973 Macmillan Publishers Ltd.)

Figure 6.6

The relationship between density of Acacia xanthophloea trees and soil salinity in Amboseli, Kenya. A sharp inflection point at about 7-8 ECe divides sparse from dense stands when plotted on a normal scale. (From Western and van Praet 1973. Reprinted by permission from Nature, 241, 104-106. Copyright 1973 Macmillan Publishers Ltd.)

migrants were adapted to feeding on trees. The feeding behavior of their descendants is thus maladaptive in the more arid regions of eastern and southern Africa, where grass should have been the preferred forage. There is no evidence as yet to support the view that the Central African forest-dwelling elephants dispersed to the drier parts of Africa in recent centuries. Studies on genetic relatedness among the regional populations could shed light on this issue.

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