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Abstract Detail


Ephedra pollination and other gnetalean oddities

Loera, Israel [1], Sosa, Victoria [2], Ickert-Bond, Stefanie M. [3].

Diversification in North America arid lands: niche conservatism, divergence and expansion of habitat explain speciation in the genus Ephedra.

A lineage of twelve arid land shrubby species in the gymnosperm genus Ephedra (Gnetales) from North America is used to evaluate the influence of climate on speciation. Using Bayesian Inference we analyzed a combined matrix of seven DNA molecular markers to infer sister species and to estimate time of divergence of lineages. Ecological niche models based on climatic variables are generated for four parapatric and sympatric sister species. Two analyses of niche evolution are performed, one based on ecological niche models and another using raw data and multivariate analysis. As previous analyses suggest, the diversification of North America Ephedra species may be the result of a recent radiation. The estimated divergence time of three pairs of sister species distributed in southwestern North America (E. cutleri - E. aspera, E. californica - E. trifurca and E. torreyana - E. viridis) is inferred to have occurred in the Late Miocene to Pliocene and for the sister species pair E. antisyphilitica - E. coryi distributed in the southern United States and northeastern Mexico, it was inferred from the Pliocene to Pleistocene. Both parapatric and sympatric species diverged mostly in a scenario of climatic niche conservatism. However, the multivariate analysis found environmental differences between sister species and several precipitation and temperature variables differ significantly in these taxa suggesting also niche divergence. Despite little climatic divergence detected there are species traits that may be involved in the divergences. Two sister species differ in the soil type in which they occur, whereas another pair differs in dispersal syndrome. The orogenetic and climatic changes related to expansion of arid lands in North America may have contributed to diversification in Ephedra, rather than adaptations to new climatic conditions.

Broader Impacts:


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1 - Instituto De Ecologia, A. C., Biologia Evolutiva, Apartado Postal 63, Xalapa, Veracruz, 91000, Mexico
2 - INSTITUTO DE ECOLOGIA A.C., APDO POSTAL 63, XALAPA, Veracruz, N/A, 91000, Mexico
3 - University Of Alaska Museum Of The North, Herbarium (ALA) And Dept. Of Biology And Wildlife, University Of Alaska Fairbanks, 907 Yukon Dr., Fairbanks, AK, 99775, USA

Keywords:
Ephedra
niche conservatism
aridlands
speciation.

Presentation Type: Symposium or Colloquium Presentation
Session: SY01
Location: Delaware A/Hyatt
Date: Monday, July 9th, 2012
Time: 9:00 AM
Number: SY01003
Abstract ID:458


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