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Evidence that divergent selection shapes a developmental cline in a forest tree species complex

journal contribution
posted on 2023-05-19, 19:18 authored by Costa e Silva, J, Peter HarrisonPeter Harrison, Robert Wiltshire, Bradley PottsBradley Potts

Background and Aims: Evolutionary change in developmental trajectories (heterochrony) is a major mechanism of adaptation in plants and animals. However, there are few detailed studies of the variation in the timing of developmental events among wild populations. We here aimed to identify the climatic drivers and measure selection shaping a genetic-based developmental cline among populations of an endemic tree species complex on the island of Tasmania.

Methods: Seed lots from 38 native provenances encompassing the clinal transition from the heteroblastic Eucalyptus tenuiramis to the homoblastic Eucalyptus risdonii were grown in a common-garden field trial in southern Tasmania for 20 years. We used 27 climatic variables to model the provenance variation in vegetative juvenility as assessed at age 5 years. A phenotypic selection analysis was used to measure the fitness consequences of variation in vegetative juvenility based on its impact on the survival and reproductive capacity of survivors at age 20 years.

Key Results: Significant provenance divergence in vegetative juvenility was shown to be associated with home-site aridity, with the retention of juvenile foliage increasing with increasing aridity. Our results indicated that climate change may lead to different directions of selection across the geographic range of the complex, and in our mesic field site demonstrated that total directional selection within phenotypically variable provenances was in favour of reduced vegetative juvenility.

Conclusions: We provide evidence that heteroblasty is adaptive and argue that, in assessing the impacts of rapid global change, developmental plasticity and heterochrony are underappreciated processes which can contribute to populations of long-lived organisms, such as trees, persisting and ultimately adapting to environmental change.

History

Publication title

Annals of Botany

Volume

122

Pagination

181-194

ISSN

0305-7364

Department/School

School of Natural Sciences

Publisher

Oxford Univ Press

Place of publication

Great Clarendon St, Oxford, England, Ox2 6Dp

Rights statement

© The Author(s) 2018. All rights reserved.

Repository Status

  • Restricted

Socio-economic Objectives

Terrestrial biodiversity