Abstract Detail



Macroevolution

Larcombe , Matthew James [1], Jordan, Gregory [2], Higgins, Steven, I [3].

Paleoendemics and the extinction conundrum: past performance is not a good predictor of future performance.

Paleoendemics are old and isolated taxa. That is, monophyletic lineages on long branches that are geographically isolated relative to their age. A classic example is Amborellaeace, which as sister to all other angiosperms, is probably between 250 and 140 Mya old, and is restricted to a single island in New Caledonia. Paleoendemics can be monotypic like Amborella or they may be phylogenetically and geographically isolated groups (clades). They are interesting because they harbor unique genetic and possibly functional diversity, and can provide a means of reconstructing paleo-climates, especially where multiple paleoendemic lineages occur in the same location or climate space. Conceptually paleoendmics poses a conundrum in terms of extinction risk. On one hand, their antiquity suggests that they are exceptionally resilient to extinction, possibly implying they possess traits that make them unusually resistant to change and extirpation. On the other hand, their restricted distribution means they are currently at high risk of extinction relative to widespread, often younger taxa. We think it is unlikely that paleoendemics have special resilience to extinction, and their long survival more reflects a coincidence between traits, geography and environmental change. Therefore, we predict that paleoendemics will be least as threatened by future climate change as non-paleoendemics. We test this hypothesis in the paleoendemic rich conifer clade. We use process-based niche modeling to predict the historic (mid-Holocene) current and future (2070) distribution of 450 extant conifer species, and determine how climate change and level of paleoendemism influence extinction risk. Shifting just 50 years in the future caused the greatest loss of known locations across all taxa. Furthermore, there was virtually no relationship between paleoendemism and extinction risk when shifting to historic climates, but a strong positive relationship when shifting to future climates. This suggests that paleoendemics have been good at surviving the types of change that occurred in the past, but that that has not equipped them to cope with future change. Thus, despite their longevity, paleoendemics are more vulnerable to extinction than other taxa in the near future. Research showing that paleoendemics (including conifers) cluster in both geographic and climate space raises hope that conservation interventions that target certain regions might benefit many of these unique lineages.   


1 - University of Otago, Department of Botany, PO Box, 56, Dunedin, New Zealand (NZL), 9054, New Zealand
2 - University Of Tasmania, SCHOOL OF BIOLOGICAL SCIENCES, Private Bag 55, Hobart, Tas, TAS, 7001, Australia
3 - University of Bayreuth, Plant Ecology, University of Bayreuth, Universitätstraße 30, Bayreuth, 95447, Germany

Keywords:
Paleoendemics 
Extinction
Conifers
climate change
ecological niche modelling.

Presentation Type: Oral Paper
Number: MACRO2006
Abstract ID:700
Candidate for Awards:None


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