ISHS Acta Horticulturae 615: IV International Conifer Conference
THE EVOLUTION, BIOGEOGRAPHY AND PALAEOECOLOGY OF THE PINACEAE BASED ON FOSSIL AND EXTANT REPRESENTATIVES |
| Author: | B.A. LePage |
| Keywords: | climate, DNA, Larix, mycorrhizae, phylogeny, Picea, Pseudolarix, Tsuga |
| Abstract:
The fossil record of the family Pinaceae indicates that most genera first appeared in the high-latitude and high-altitude regions of North America during the early Tertiary. In fact, six of the eleven genera recognised currently in the Pinaceae, including the earliest known representatives of Larix Miller, Tsuga (Endlicher) Carrière, Picea A. Dietrich, and Keteleeria Carrière, are represented in the high-latitude middle Eocene deposits of the Buchanan Lake Formation at Napartulik on Axel Heiberg Island, Arctic Canada. The abundance and quality of preservation of these early pinaceous representatives enabled detailed morphological assessment of the characters thought to be diagnostic, and provided the framework in which to interpret the phylogenetic and biogeographic histories of some of these genera. The results revealed significant morphological variation of the characters thought previously to be diagnostic and demonstrated their limited utility for meaningful taxonomic circumscription, while reinforcing the notion that bract morphology, a little used character that has been shown to be reliable for species-level discrimination, is important taxonomically. In addition, consideration of the spatial and temporal distribution patterns of a number of these genera together with aspects of global climatic and environmental change, mountain-building events, and nutrient acquisition strategies provides a possible explanation for the patterns of taxonomic diversity and evolutionary history of some of the genera of the Pinaceae. | |
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