Presentation Detail

Community Ecology and Evolution

Miller, Eliot [1], Westoby, Mark [2], Ricklefs, Robert [1].

Contrasting patterns of diversification across Australian climate gradients.

Due to phylogenetic niche conservatism, most extant members of a clade are thought to remain in ancestral environments because expansion into new environmental space imposes an adaptive load on a population. This hypothesis predicts that local assemblages contain increasingly phylogenetically clustered subsets of species with increasing difference from the ancestral environment of a clade. We test this prediction in two clades: Australian Meliphagidae, a continental radiation of birds that originated in wet, subtropical environments but subsequently spread to drier environments as Australia became more arid during the late Cenozoic; and the Hakeinae, a large radiation of shrubs found across Australia, particularly in open habitats. We find that Meliphagidae assemblages are increasingly phylogenetically clustered along a gradient of decreasing precipitation. Somewhat differently, the Hakeinae exhibit a more complicated pattern of clustering both with decreasing precipitation and increasing temperature. We develop a novel phyloclimatespace approach to characterize evolution through climate space of these disparate lineages. This approach illustrates in graphical form the rarity with which Meliphagidae lineages have evolved towards drier habitats. It shows Hakeinae have radiated widely in cooler regions, including arid areas, but have only occasionally moved into warm, wet areas (which are often closed canopy forests in Australia). We suggest that in Meliphagidae, this reflects the difficulty of surviving in arid areas, either because of strict physiological tolerances or an inability to find sufficient resources (“habitat filtering�). In contrast, we suggest the infrequency of Hakeinae lineages having evolved into closed forests is more directly related to the conservatism of their growth form, and its lack of competitive ability in these environments (“competitive exclusion�). Interestingly, in this case disparate ecological processes are believed to have led to similar patterns in phylogenetic community structure. Like Mayfield and Levine, we suggest that accepting phylogenetic patterns as evidence of ecological processes may be an oversimplification, but we also take a middle ground and advocate that quantification of such patterns can be part of a multi-faceted approach to understanding diversity and community assembly processes.

1 - University of Missouri, St. Louis, Biology, Saint Louis, MO, 63121, USA
2 - Macquarie University, Biology, Sydney, NSW, Australia

Keywords:
Phylogenetic niche conservatism
Phyloclimatespace
community assembly
phylogenetic comparative methods
Range size.

Presentation Type: Regular Oral Presentation
Session: 129
Location: Peruvian A/Snowbird Center
Date: Tuesday, June 25th, 2013
Time: 8:30 AM
Number: 129001
Abstract ID:549
Candidate for Awards:W.D. Hamilton Award for Outstanding Student Presentation