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A Comparison of Temperate and Tropical Cave Communities
Robert W. Mitchell
The Southwestern Naturalist
Vol. 14, No. 1 (May 16, 1969), pp. 73-88
Published by: Southwestern Association of Naturalists
Stable URL: http://www.jstor.org/stable/3669249
Page Count: 16
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World-wide troglobite (obligate cavernicole) distribution patterns are reviewed. The troglobite faunas of the Edwards Plateau of Texas and the Sierra de El Abra of Mexico are compared and related to the world-wide distributions. Striking differences exist between temperate and tropical cave communities. Temperate caves contain far more troglobites than tropical caves. Terrestrial troglobites in particular are uncommon in tropical caves; most tropical troglobites are aquatic. Several suggestions are offered in explanation of these disparities. The paucity of tropical troglobites is possibly a reflection of the higher energy input into tropical caves which lessens the selection pressures for energy-economizing troglobite adaptations. Consequently, evolutionary rates are slowed, and troglobites appear later in tropical caves than in temperate caves of lower energy input. Abundance of terrestrial troglobites in temperate caves has resulted largely from the effects of Pleistocene glaciation which removed surface faunas leaving populations in protective cave environments to evolve in geographical isolation. The absence of these effects in tropical areas and the nature of the tropical climate permit continuing gene exchange between cave and surface populations preventing speciation. Most tropical troglobites are aquatic since aquatic populations may be geograhically isolated in caves by means ineffective in the isolation of terrestrial populations.
The Southwestern Naturalist © 1969 Southwestern Association of Naturalists