Abstract Detail

Biogeography

Edwards, Robert D. [1], Crisp, Michael [2], Cook, Lyn [3].

Species limits in a widespread Australasian monsoon-tropics tree complex (Melaleuca leucadendra group - Myrtaceae) and the role of multiple biogeographic barriers in differentiation.

Broadleaved Paperbarks (Melaleuca leucadendra group) are a dominant component of Australia’s monsoon savannah with 15 morphospecies typically nominated, all overlapping for some part of their range. While it is suggested that edaphic gradients may separate species at a local scale, full morphological differentiation in many populations appears to break down, indicating either a lack of divergence, or divergence with subsequent introgression. Using nuclear and chloroplast data to test traditional species boundaries we found considerable congruence, and patterns consistent with incomplete linage sorting.
Surprising levels of geographic structure in the chloroplast markers led us to further explore the role that biogeographic barriers may play in differentiating populations and species. We identified 13 biogeographic barriers that limit the distribution of a significant proportion of all Australian tropical plant species. Across these barriers there was evidence for reduced gene flow within a number of Broadleaved Paperbark populations, including the recognition of a new species isolated by the Great Sandy Desert. However, the deepest divergence within the group appears to be associated with a barrier cryptic to contemporary species distributions. Here we hypothesize vicariance of multiple species across The Great Dividing Range and subsequent divergence with re-expansion into secondary contact. These exploratory results suggest a complex interplay between geography and environment in the history of this group.

1 - University of Rochester, Biology, Hutchinson Hall, Rochester, NY, 14627, USA
2 - The Australian National University, Daley Rd, Building 116, ANU, Canberra, N/A, 0200, Australia
3 - The University of Queensland, School of Biological Sciences, Brisbane, QLD, 4072, Australia

Keywords:
biogeography
Barriers
speciation
Myrtaceae
Australia.

Presentation Type: Oral Paper:Papers for Topics
Session: 72
Location: Salon 3/The Shaw Conference Centre
Date: Wednesday, July 29th, 2015
Time: 4:30 PM
Number: 72011
Abstract ID:1308
Candidate for Awards:None