Recurrent origin of peripheral, coastal (sub)species of Mediterranean Senecio (Asteraceae)
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Background: It is argued that coastal endemic taxa may evolve in parallel at the periphery of the distributional range of a widespread species. Aims: We tested this hypothesis for the origins of three peripheral, coastal isolates of Senecio, S. glaucus ssp. glaucus (Israel), S. g. ssp. coronopifolius p.p. (Sicily), and S. hesperidium (Morocco), from widespread S. glaucus ssp. coronopifolius. We also determined the relative roles of selection vs. genetic drift in shaping phenotypic divergence in ssp. glaucus and S. hesperidium, using Lande’s test of neutral morphological change. Methods: We surveyed morphological and/or allozyme variation in the three peripheral isolates and mainly inland populations of S. g. ssp. coronopifolius. Results: Genetic data supported independent origins of the coastal taxa from nearby populations of ssp. coronopifolius. These descendant and ancestral populations showed pronounced morphological but weak genetic differentiation. Phenotypic similarities between ssp. glaucus (Israel) and S. hesperidium (Morocco) in plant height and floral traits may have resulted from parallel divergent selection from ssp. coronopifolius, though drift remains an alternative cause in S. hesperidium. Conclusions: Our results indicate parallel ecotype formation and (sub)speciation in Senecio in which primarily selective vs. neutral determinants promoted the recurrent origin of coastal types in, respectively, Israel and Morocco.
Comes , H P , Coleman , M & Abbott , R J 2017 , ' Recurrent origin of peripheral, coastal (sub)species of Mediterranean Senecio (Asteraceae) ' Plant Ecology & Diversity , vol 10 , no. 4 , pp. 253-271 . DOI: 10.1080/17550874.2017.1400127
Plant Ecology & Diversity
© 2017 Botanical Society of Scotland and Taylor & Francis. This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License (http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited, and is not altered, transformed, or built upon in any way.
The work was funded in part by the Biotechnology and Biological Sciences Research Council (UK) in the form of a research studentship awarded to MC.
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