Is mahogany dysgenically selected?

Cornelius, J.P., Navarro, C.M., Wightman, K.E., and Ward, S.E. (2005) Is mahogany dysgenically selected? Environmental Conservation, 32 (2). pp. 129-139.

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One concern in the ongoing debate over the conservation status of mahogany has been the possibility that selective logging, as a form of negative phenotypic selection, might have led to deterioration in the genetic quality of populations. The incidence and degree of such ‘dysgenic’ effects is discussed, based on a consideration of mahogany logging practices, their expected genetic effects and empirical data on phenotypic selection in forest trees. Loggers have tended to avoid diseased, small, very large and poorly-formed individuals, and consequently logging has tended to increase the proportion of poor quality phenotypes relative to that before logging; in at least some conditions, selection differentials have been strongly negative. However, the upper limit for heritability of logger-selected traits in naturally-regenerated mahogany is probably no more than c. 0.1. Consequently, and assuming relatively extreme but realistic negative selection differentials of 50%, the maximum negative dysgenic response to a single logging-mediated phenotypic selection event is expected to be relatively small, i.e. [less-than-or-equal]5%. This expectation is consistent with the empirical information from mahogany and other taxa. The implications of any dysgenic effects depend very much on the use and the future of dysgenically-selected populations. In managed populations, dysgenic effects could be reversed through positive selection. In the case of exploited but currently unmanaged natural populations, dysgenic selection is primarily of importance insofar as it affects fitness. As a threat to mahogany conservation and long-term sustainable production, it is probably insignificant in comparison with other genetic and non-genetic factors.

Item ID: 10458
Item Type: Article (Research - C1)
ISSN: 1469-4387
Keywords: dysgenic selection, genetic erosion, Meliaceae, Neotropics, selective logging, Swietenia
Date Deposited: 15 Apr 2010 06:00
FoR Codes: 07 AGRICULTURAL AND VETERINARY SCIENCES > 0705 Forestry Sciences > 070504 Forestry Management and Environment @ 80%
06 BIOLOGICAL SCIENCES > 0604 Genetics > 060411 Population, Ecological and Evolutionary Genetics @ 20%
SEO Codes: 82 PLANT PRODUCTION AND PLANT PRIMARY PRODUCTS > 8201 Forestry > 820104 Native Forests @ 80%
96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960806 Forest and Woodlands Flora, Fauna and Biodiversity @ 20%
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