Diversification and the evolution of dispersal ability in the tribe Brassiceae (Brassicaceae)

C. G. Willis, J. C. Hall, R. Rubio De Casas, T. Y. Wang, K. Donohue

Research output: Contribution to journalArticlepeer-review

26 Scopus citations

Abstract

Background and Aims Dispersal and establishment ability can influence evolutionary processes such as geographic isolation, adaptive divergence and extinction probability. Through these population-level dynamics, dispersal ability may also influence macro-evolutionary processes such as species distributions and diversification. This study examined patterns of evolution of dispersal-related fruit traits, and how the evolution of these traits is correlated with shifts in geographic range size, habitat and diversification rates in the tribe Brassiceae (Brassicaceae). Methods The phylogenetic analysis included 72 taxa sampled from across the Brassiceae and included both nuclear and chloroplast markers. Dispersal-related fruit characters were scored and climate information for each taxon was retrieved from a database. Correlations between fruit traits, seed characters, habitat, range and climate were determined, together with trait-dependent diversification rates. Key Results It was found that the evolution of traits associated with limited dispersal evolved only in association with compensatory traits that increase dispersal ability. The evolution of increased dispersal ability occurred in multiple ways through the correlated evolution of different combinations of fruit traits. The evolution of traits that increase dispersal ability was in turn associated with larger seed size, increased geographic range size and higher diversification rates. Conclusions This study provides evidence that the evolution of increased dispersal ability and larger seed size, which may increase establishment ability, can also influence macro-evolutionary processes, possibly by increasing the propensity for long-distance dispersal. In particular, it may increase speciation and consequent diversification rates by increasing the likelihood of geographic and thereby reproductive isolation.

Original languageEnglish (US)
Pages (from-to)1675-1686
Number of pages12
JournalAnnals of Botany
Volume114
Issue number8
DOIs
StatePublished - Dec 1 2014

Bibliographical note

Funding Information:
This work was supported in part by NSF Doctoral Dissertation Improvement Grant #1011329. The authors thank Elena Kramer, Paul Manos, Cliff Cunningham, Mark Rausher, John Willis and members of the Donohue Lab for comments on the manuscript, and Tracy Tisdale and Jamie Sabo for their participation in this project.

Keywords

  • Brassica
  • Brassicaceae
  • Cakile
  • Extinction
  • Fruit traits
  • Heteroarthrocarpy
  • Limited dispersal
  • Longdistance dispersal
  • Range size
  • Speciation
  • Species diversification

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