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Abstract Detail


Cantley, Jason [1], Jobson, Peter [2], Lacey, L. Mae [1], Frawley, Emma [1], Martine, Christopher [1].

A look into the biogeography of multiple narrowly endemic sandstone escarpment lineages of the Australian Monsoon Tropics.

The Australian Monsoon Tropics (AMT) is one of the least disturbed tropical biomes on the planet, encompassing nearly the northern 1/3 of Australia. Surprisingly little is known about the evolution of its flora or how past geologic and climatic events may have shaped it, particularly during the dynamic climate fluctuations of the Quaternary that ushered in numerous periods of hyper-aridity. Our investigation considers the biogeographic origins and patterns of historical distribution for multiple lineages of narrowly endemic AMT angiosperm taxa across both spatial and temporal scales. Lineages typically occur along the escarpment edges of three major sandstones that support a sporadically distributed microclimate maintained by shaded gorges and some orographic precipitation. Such is the case for the two focal lineages of this presentation: a monophyletic clade of andromonoecious Solanum taxa and taxa of Acacia section Lycopodiifoliae. We hypothesize that: a) the same natural breaks occur within the geographic ranges of multiple unrelated angiosperm lineages, and that b) these breaks reflect barriers formed during unfavorable glacial periods of hyper-aridity when escarpment microclimates acted as habitat refugia. To uncover current AMT biogeographic patterns, we sampled across populations and constructed molecular phylogenies in order to understand phylogenetic relationships and time of lineage divergence obtained from molecular clock techniques. Descriptive statistics and demographic modeling then allow for the inference of effective breeding sizes through time to investigate historical bottlenecks, periods of range expansion, and post-divergence genetic migration among both populations and taxa. Phylogenetic and demographic data are then correlated with niche models of each taxon’s present day distribution via robust geospatial data, which in turn was combined with Global Circulation Models to help illuminate historical areas of suitable habitat during the Last Glacial Maximum (LGM) when the AMT was last postulated to have undergone a period of hyper-aridity.

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1 - Bucknell University, 1 Dent Drive, Lewisburg, Pennsylvania, 17837, United States
2 - Northern Territory Government, Land Resource Management

Last Glacial Maximum
primarily undergraduate institution

Presentation Type: Oral Paper
Number: 19002
Abstract ID:114
Candidate for Awards:George R. Cooley Award

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