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Abstract Detail



Molecular Ecology and Evolution

Humphreys , Aelys M [1], Barraclough, Timothy G [1], Rydin, Catarina [2].

Evolution of gymnosperms into independently evolving higher clades.

There is currently widespread, renewed interest in estimating speciation and extinction rates from molecular phylogenies. This renewed interest is, in part, due to recent mathematical advances that have allowed researchers to take into account rate heterogeneity over time and among lineages, which in turn has provided estimates that are more biologically plausible and more in agreement with patterns in the fossil record. One remaining difficulty is which clades to analyse separately. The choice of clade is not trivial because processes operating in one clade may mask the signature of processes operating in other clades. Higher taxa, such as genera or families, tend to be used even though it is widely acknowledged that higher taxa are not comparable among groups and are generally not considered to represent evolutionary units in the same way as species are. However, it has recently been shown that processes known to underlie species formation, geographical isolation and divergent selection, can generate evolutionarily significant units above the species (hESUs). In mammals these units tend to correspond to traditionally recognised families or inframilial taxa, and rarely to genera, and there is evidence to suggest that their formation followed occupation of distinct ecological zones (“adaptive zones”). By definition these clades are independently evolving, meaning that different rules govern speciation and extinction of different hESUs. In theory, hESUs are therefore ideal for inferring diversification dynamics of extant clades. In this poster we demonstrate this approach and present results for ancient seed plants: gymnosperms. We find strong evidence that gymnosperm evolution has not followed a constant-rates birth-death process and that gymnosperms have diverged into hESUs. In contrast to mammals, gymnosperm hESUs tend to correspond to genus-level taxa or below.


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1 - Imperial College London, Department of Life Sciences, Silwood Park Campus, Ascot, Berkshire, SL57PY, UK
2 - Stockholm University, Department of Ecology, Environment and Plant Sciences, Sweden

Keywords:
gymnosperms evolution
Gnetales
cycads
conifers
higher ESUs.

Presentation Type: Poster:Posters for Topics
Session: P
Location: Eyrie/Boise Centre
Date: Monday, July 28th, 2014
Time: 5:30 PM
Number: PME007
Abstract ID:589
Candidate for Awards:None


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