Abstract Detail

Biogeography

Leslie, Andrew [1], Donoghue, Michael [2], Mathews, Sarah [3], Beaulieu, Jeremy [4], Jetz, Walter [2].

Conifer diversity hotspots along a museum-to-cradle continuum.

Regions of exceptional species richness, or hotspots, provide key insights into the factors that drive diversification and structure biogeographic patterns at large scales. Teasing apart the various processes that contribute to high species richness, such as high origination rates, low extinction rates, and/or high migration rates, is often challenging and requires detailed phylogenetic and geographic information that is missing for many groups of organisms. In this study, we focus on understanding the processes that generate species richness hotspots in one group of woody plants, the conifers, for which we have detailed phylogenetic and geographic information. We use a new time-calibrated molecular phylogeny that samples 90% of extant species, combined with geographic range data for nearly every living species, to identify hotspots of exceptional species richness and characterize their phylogenetic structure using metrics such as evolutionary distinctiveness (ED) and net relatedness index (NRI). In particular, we use these metrics to ask if conifer hotspots are generally “cradles” that have fostered diversification or “museums” that have preserved diversity. The fourteen hotspot regions that we identify, which span northern temperate to tropical environments, are highly diverse in their phylogenetic structure and many do not fall cleanly into either “cradle” or “museum” categories. In particular, Northern Hemisphere hotspots fall along a wide spectrum from regions composed of deeply branched, unrelated species to those composed of recently diverged and closely related species. These differences appear to be driven primarily by precipitation; wet hotspots preserve more deeply divergent lineages while dry hotspots are dominated by a few lineages have recently radiated in harsher environments. Hotspots in tropical and Southern Hemisphere environments, in contrast, consist of species that are both deeply branched and closely related. This phylogenetic structure, which is absent in the Northern Hemisphere, likely reflects the slower, but steady, diversification of subclades within genera such as Podocarpus and Dacrydium that are well adapted to tropical montane forests. These results highlight the differences in conifer diversification dynamics between the hemispheres, the important role of high precipitation habitats in preserving deeply branched lineages in general, and the need for a nuanced terminology to describe the many different ways in which regions of high species richness may arise.

1 - Brown University, Ecology and Evolutionary Biology, Box G-W, 80 Waterman Street, Providence, RI, 02912, USA
2 - Yale University, Department Of Ecology And Evolutionary Biology, 21 Sachem Street, PO BOX 208105, New Haven, CT, 06511, USA
3 - Australian National University, Centre for Biodiversity Analysis, Canberra, Australia
4 - University of Tennessee, Ecology and Evolutionary Biology, 569 Dabney Hall, Knoxville, TN, 37996, USA

Keywords:
hotspot
conifers
phylogeny
diversification.

Presentation Type: Oral Paper
Session: 30, Biogeography I
Location: 203/Savannah International Trade and Convention Center
Date: Tuesday, August 2nd, 2016
Time: 4:15 PM
Number: 30011
Abstract ID:272
Candidate for Awards:None