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No outbreeding depression at a regional scale for a habitat-forming intertidal alga with limited dispersal

journal contribution
posted on 2006-08-31, 00:00 authored by Prudence McKenzie, Alecia BellgroveAlecia Bellgrove
Hormosira banksii is distributed throughout southern Australasia, but dispersal of propagules is thought to be limited. In the present study, the hypothesis that outbreeding depression occurs in H. banksii was tested by assessing fertilisation success and early development of embryos in crosses between populations at local to regional spatial scales. Hierarchical experiments were conducted at three spatial scales with nesting present within each scale: small scale (within a rocky shore population), intermediate scale (regions separated by 70 km) and large scale (450-km separation between two states: Victoria and Tasmania). In each experiment, eggs and sperm were crossed within and between each population located in the spatial scale of interest. There were no consistent patterns of variable fertilisation success and subsequent development within a population or at different spatial scales. It was concluded that outbreeding depression is not detected in analyses of fertilisation success or early development processes in H. banksii. The results suggest one of the following to be likely: (1) H. banksii is capable of longer distance dispersal than previously considered, thus maintaining gene flow between distant populations, (2) gene flow is restricted by limited dispersal, but populations have not been isolated for a sufficient length of time to cause genetic divergence or (3) outbreeding depression is manifested as effects on later life-history stages.

History

Journal

Marine & freshwater research

Volume

57

Issue

6

Pagination

655 - 663

Publisher

CSIRO Publishing

Location

Collingwood, Vic.

ISSN

1323-1650

eISSN

1448-6059

Language

eng

Publication classification

C1 Refereed article in a scholarly journal

Copyright notice

2006, CSIRO