Recurrent origin of peripheral, coastal (sub)species of Mediterranean Senecio (Asteraceae)

Hans Peter Comes, Max Coleman, Richard J. Abbott

Research output: Contribution to journalArticlepeer-review

Abstract

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.
Original languageEnglish
Pages (from-to)253-271
JournalPlant Ecology & Diversity
Volume10
Issue number4
Early online date14 Dec 2017
DOIs
Publication statusPublished - Dec 2017

Keywords

  • Allozyme diversity
  • Asteraceae
  • Genetic drift
  • Mediterranean
  • Morphometrics
  • Natural selection
  • Parallel speciation
  • Senecio

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