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Ecological plasticity of Southern Ocean bivalves from contrasting environments

Ecological plasticity of Southern Ocean bivalves from contrasting environments
Ecological plasticity of Southern Ocean bivalves from contrasting environments
The ability of a species to show plasticity throughout its range is suggested to be significant to the survival, maintenance, and expansion of populations. In the Southern Ocean, plastic traits may have enabled resilience since the onset of cooling, and given species the capacity to exploit empty niches after the retreat of ice in interglacial periods. Phenotypic plasticity has rarely been investigated in Southern Ocean invertebrates however, and the cold stenothermal environment, which prevails, has often been considered homogenous in its selection on fauna. Previous ecological studies have often pooled together material collected within predetermined biogeographic regions to overcome the limitations of sampling difficulties. Subtle differences between environments may however, be forcing ecological divergence in species, with possible implications for speciation processes. This thesis investigates the phenotypic plasticity and reproduction among populations of the small shallow-water brooding bivalve Lissarca miliaris over its Antarctic range, and of deep-sea protobranch bivalves Yoldiella ecaudata, Y. sabrina, and Y. valettei from contrasting benthic regions.

The reproductive studies of L. miliaris revealed a previously unknown hermaphrodite trait, maximising the reproductive efficiency in a short-lived species where the female’s capacity to brood its young is limited. Reproduction is also described for the first time in deep-sea Antarctic protobranch bivalves and demonstrates lecithotrophic larval development. Additionally, Y. valettei shows evidence of simultaneous hermaphroditism, which may increase the likelihood of successful reproduction in low population densities. Phenotypic plasticity is observed among populations of bivalves, irrespective of geographical proximity, and with no latitudinal trends, but subtle differences in the environment. Significant differences in morphology and growth rates are identified among populations, and reproductive plasticity identified in L. miliaris and Y. sabrina. Increasing atmospheric temperature is also measured to show an effect on the ecophysiology of intertidal populations of L. miliaris at Signy Island over the past 40 years, with increasing growth rates at the cost of smaller offspring and pressure from endolithic algal decay.
Reed, Adam Jerold
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Reed, Adam Jerold
022dea24-95cb-4459-b969-3c0cd297ef0b
Thatje, Sven
f1011fe3-1048-40c0-97c1-e93b796e6533

(2013) Ecological plasticity of Southern Ocean bivalves from contrasting environments. University of Southampton, Ocean and Earth Science, Doctoral Thesis, 246pp.

Record type: Thesis (Doctoral)

Abstract

The ability of a species to show plasticity throughout its range is suggested to be significant to the survival, maintenance, and expansion of populations. In the Southern Ocean, plastic traits may have enabled resilience since the onset of cooling, and given species the capacity to exploit empty niches after the retreat of ice in interglacial periods. Phenotypic plasticity has rarely been investigated in Southern Ocean invertebrates however, and the cold stenothermal environment, which prevails, has often been considered homogenous in its selection on fauna. Previous ecological studies have often pooled together material collected within predetermined biogeographic regions to overcome the limitations of sampling difficulties. Subtle differences between environments may however, be forcing ecological divergence in species, with possible implications for speciation processes. This thesis investigates the phenotypic plasticity and reproduction among populations of the small shallow-water brooding bivalve Lissarca miliaris over its Antarctic range, and of deep-sea protobranch bivalves Yoldiella ecaudata, Y. sabrina, and Y. valettei from contrasting benthic regions.

The reproductive studies of L. miliaris revealed a previously unknown hermaphrodite trait, maximising the reproductive efficiency in a short-lived species where the female’s capacity to brood its young is limited. Reproduction is also described for the first time in deep-sea Antarctic protobranch bivalves and demonstrates lecithotrophic larval development. Additionally, Y. valettei shows evidence of simultaneous hermaphroditism, which may increase the likelihood of successful reproduction in low population densities. Phenotypic plasticity is observed among populations of bivalves, irrespective of geographical proximity, and with no latitudinal trends, but subtle differences in the environment. Significant differences in morphology and growth rates are identified among populations, and reproductive plasticity identified in L. miliaris and Y. sabrina. Increasing atmospheric temperature is also measured to show an effect on the ecophysiology of intertidal populations of L. miliaris at Signy Island over the past 40 years, with increasing growth rates at the cost of smaller offspring and pressure from endolithic algal decay.

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Published date: 3 April 2013
Organisations: University of Southampton, Ocean and Earth Science

Identifiers

Local EPrints ID: 359130
URI: http://eprints.soton.ac.uk/id/eprint/359130
PURE UUID: c014f8c6-76e4-4ee4-ab68-1c7f0577ac17

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Date deposited: 24 Oct 2013 13:03
Last modified: 20 Apr 2018 16:32

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