ISHS Acta Horticulturae 615: IV International Conifer Conference
TOWARDS A BIOGEOGRAPHY OF THE PODOCARPACEAE |
| Author: | R.R. Mill |
| Keywords: | Acmopyle, adaptive radiation, dispersal, Dacrycarpus, Dacrydium, endozoochory, Falcatifolium, palaeogeography, Podocarpu |
| Abstract:
The biogeography of Podocarpaceae is discussed in relation to extant and fossil taxa and the palaeogeography of areas presently occupied by podocarps. The role of vertebrate dispersal is briefly outlined. Endozoochory is important for present short- and medium-distance dispersal; however, past long-distance dispersal events, leading to some present disjunct distribution patterns, are more likely to have resulted through rafting on microcontinental blocks and their subsequent accretion on to other land masses. Malesia and Australasia have the greatest diversity of living podocarps but, because podocarps only immigrated to Malesia from the south in relatively recent geological times (principally post-Miocene) and there neither are, nor have been, any endemic genera there, Malesia is regarded as a refugium in which there has been adaptive radiation in response to edaphic and insular factors. New Zealand and South America-Antarctica have the greatest diversities of fossil podocarps; the fossil podocarp flora of New Zealand is more recent than, and probably largely derived from, that of Australia, which has fewer endemic fossil or living genera. Thus it is considered that, as in Nothofagus, South America – Antarctica are possibly the cradle of much of the modern podocarp flora, and that the diverse New Zealand fossil podocarp flora is an example of secondary radiation. New Caledonia is another centre of adaptive radiation for living podocarps. It appears to be where the least derived members of Podocarpus subgenus Foliolatus are preserved; the subgenus may have radiated from there to the islands of Malesia and the rest of tropical Asia. Brief case studies concerning Acmopyle, Dacrydium, Dacrycarpus and Falcatifolium are presented. | |
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