Patterns of genetic variation in tree species and their implications for conservation

Authors: Premoli, A.C., Newton, A.C. et al.

Pages: 120-156

ISBN: 9781845932619

Abstract:

Within-species genetic variability is essential for the maintenance of the evolutionary potential of natural populations. Information from genetic markers can help inform the development of conservation strategies, including those for endemic tree species. This chapter summarizes the results of recent research into the conservation genetics of tree species inhabiting temperate forests of southern Argentina and Chile, and montane forests of northern Argentina and Mexico. Pronounced genetic differences were recorded between populations of all species studied, reflecting their complex biogeographic and evolutionary histories. Species such as Araucaria, Fitzroya and Pilgerodendron appear to have survived in multiple refugia during Pleistocene glaciations, indicated by marked genetic differentiation over small geographical areas. Patterns of variation in the latter two species strongly support the suggestion of local refugia persisting east of the Andes during the last glacial period. Montane species inhabiting subtropical latitudes, such as Podocarpus parlatorei and Pinus chiapensis, appear to have migrated in elevation during periods of climatic change. In each case, the result is a complex pattern of local population differentiation and adaptation, differing markedly from north temperate tree taxa characterized by large-scale postglacial migrations. Some species, including Pinus chiapensis, Pilgerodendron uviferum and Nothofagus pumilio, displayed evidence of low genetic variation within populations, reflecting the possible occurrence of inbreeding and genetic drift as a result of population isolation. This is despite their possession of life history attributes (such as wind pollination) that imply gene flow over long distances. Results suggest that gene flow may often be restricted, even in wind-pollinated species, in fragmented forest landscapes. However, weak effects of fragmentation were measured in the self-incompatible Embothrium coccineum. In this species, higher pollinator activity in fragments reduces selfing, thereby buffering genetic erosion and maintaining adaptive variation. Such results highlight the difficulty of generalizing about the impacts of anthropogenic disturbance on patterns of genetic variation in tree species. These results emphasize the importance of including many populations in conservation strategies and action plans, if the full variation within a species is to be conserved. Particular priorities for conservation include areas of high genetic diversity, which may coincide with putative glacial refugia, such as the coastal mountain range of Chile. © CAB International 2007.

Source: Scopus

Patterns of Genetic Variation in Tree Species and Their Implications for Conservation

Authors: Premoli, A.C., Newton, A. et al.

Publisher: CABI

Place of Publication: Wallingford, England

Source: Manual

Preferred by: Adrian Newton