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Phenotypic variation and fitness in a metapopulation of tubeworms (Ridgeia piscesae Jones) at hydrothermal vents.

Tunnicliffe V, St Germain C, Hilário A - PLoS ONE (2014)

Bottom Line: This foundation species at northeast Pacific hydrothermal sites occupies a wide habitat range in a highly heterogeneous environment.Although only the largest worms were measured, only 17% of low flux worms were reproductively competent compared to 91% of high flux worms.This foundation species forms a metapopulation with variable growth characteristics in a heterogeneous environment where a strategy of phenotypic variation bestows an advantage over specialization.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of Victoria, Victoria, British Columbia, Canada; School of Earth & Ocean Sciences, University of Victoria, Victoria, British Columbia, Canada.

ABSTRACT
We examine the nature of variation in a hot vent tubeworm, Ridgeia piscesae, to determine how phenotypes are maintained and how reproductive potential is dictated by habitat. This foundation species at northeast Pacific hydrothermal sites occupies a wide habitat range in a highly heterogeneous environment. Where fluids supply high levels of dissolved sulphide for symbionts, the worm grows rapidly in a "short-fat" phenotype characterized by lush gill plumes; when plumes are healthy, sperm package capture is higher. This form can mature within months and has a high fecundity with continuous gamete output and a lifespan of about three years in unstable conditions. Other phenotypes occupy low fluid flux habitats that are more stable and individuals grow very slowly; however, they have low reproductive readiness that is hampered further by small, predator cropped branchiae, thus reducing fertilization and metabolite uptake. Although only the largest worms were measured, only 17% of low flux worms were reproductively competent compared to 91% of high flux worms. A model of reproductive readiness illustrates that tube diameter is a good predictor of reproductive output and that few low flux worms reached critical reproductive size. We postulate that most of the propagules for the vent fields originate from the larger tubeworms that live in small, unstable habitat patches. The large expanses of worms in more stable low flux habitat sustain a small, but long-term, reproductive output. Phenotypic variation is an adaptation that fosters both morphological and physiological responses to differences in chemical milieu and predator pressure. This foundation species forms a metapopulation with variable growth characteristics in a heterogeneous environment where a strategy of phenotypic variation bestows an advantage over specialization.

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PCA plots paired samples based on morphological features.Using five principal components and four variables representing obturaculum-vestimentum and trunk size four groups of samples separate. PC1 explains 69% of the variability which increases to 96% with the addition of PC2. LoC, LoD and LoH were identified as immature juveniles; HiB also has many immature individuals.
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pone-0110578-g006: PCA plots paired samples based on morphological features.Using five principal components and four variables representing obturaculum-vestimentum and trunk size four groups of samples separate. PC1 explains 69% of the variability which increases to 96% with the addition of PC2. LoC, LoD and LoH were identified as immature juveniles; HiB also has many immature individuals.

Mentions: Not all samples from high flux habitats were similar. In general, sample HiA had the largest worms measured by all characters while HiB, HiD and HiH were significantly smaller than other high flux samples. For most characters, the smallest individuals were from LoC, LoD and LoH (Table 2; Table S2). The remaining low flux samples were characterized by long, very thin trunks that left most of the tube space empty. A PCA using four characters (obturaculum-vestimentum length, vestimentum width, trunk length and trunk wet weight) identified four groups: Hi samples, Lo samples, HiA and the Lo samples that were immature (Figure 6). The first two axes accounted for 96% of the variability. The HiB, HiD and HiH trio, in which less than half the animals were reproductive, fall near the immature Lo group.


Phenotypic variation and fitness in a metapopulation of tubeworms (Ridgeia piscesae Jones) at hydrothermal vents.

Tunnicliffe V, St Germain C, Hilário A - PLoS ONE (2014)

PCA plots paired samples based on morphological features.Using five principal components and four variables representing obturaculum-vestimentum and trunk size four groups of samples separate. PC1 explains 69% of the variability which increases to 96% with the addition of PC2. LoC, LoD and LoH were identified as immature juveniles; HiB also has many immature individuals.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4206443&req=5

pone-0110578-g006: PCA plots paired samples based on morphological features.Using five principal components and four variables representing obturaculum-vestimentum and trunk size four groups of samples separate. PC1 explains 69% of the variability which increases to 96% with the addition of PC2. LoC, LoD and LoH were identified as immature juveniles; HiB also has many immature individuals.
Mentions: Not all samples from high flux habitats were similar. In general, sample HiA had the largest worms measured by all characters while HiB, HiD and HiH were significantly smaller than other high flux samples. For most characters, the smallest individuals were from LoC, LoD and LoH (Table 2; Table S2). The remaining low flux samples were characterized by long, very thin trunks that left most of the tube space empty. A PCA using four characters (obturaculum-vestimentum length, vestimentum width, trunk length and trunk wet weight) identified four groups: Hi samples, Lo samples, HiA and the Lo samples that were immature (Figure 6). The first two axes accounted for 96% of the variability. The HiB, HiD and HiH trio, in which less than half the animals were reproductive, fall near the immature Lo group.

Bottom Line: This foundation species at northeast Pacific hydrothermal sites occupies a wide habitat range in a highly heterogeneous environment.Although only the largest worms were measured, only 17% of low flux worms were reproductively competent compared to 91% of high flux worms.This foundation species forms a metapopulation with variable growth characteristics in a heterogeneous environment where a strategy of phenotypic variation bestows an advantage over specialization.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of Victoria, Victoria, British Columbia, Canada; School of Earth & Ocean Sciences, University of Victoria, Victoria, British Columbia, Canada.

ABSTRACT
We examine the nature of variation in a hot vent tubeworm, Ridgeia piscesae, to determine how phenotypes are maintained and how reproductive potential is dictated by habitat. This foundation species at northeast Pacific hydrothermal sites occupies a wide habitat range in a highly heterogeneous environment. Where fluids supply high levels of dissolved sulphide for symbionts, the worm grows rapidly in a "short-fat" phenotype characterized by lush gill plumes; when plumes are healthy, sperm package capture is higher. This form can mature within months and has a high fecundity with continuous gamete output and a lifespan of about three years in unstable conditions. Other phenotypes occupy low fluid flux habitats that are more stable and individuals grow very slowly; however, they have low reproductive readiness that is hampered further by small, predator cropped branchiae, thus reducing fertilization and metabolite uptake. Although only the largest worms were measured, only 17% of low flux worms were reproductively competent compared to 91% of high flux worms. A model of reproductive readiness illustrates that tube diameter is a good predictor of reproductive output and that few low flux worms reached critical reproductive size. We postulate that most of the propagules for the vent fields originate from the larger tubeworms that live in small, unstable habitat patches. The large expanses of worms in more stable low flux habitat sustain a small, but long-term, reproductive output. Phenotypic variation is an adaptation that fosters both morphological and physiological responses to differences in chemical milieu and predator pressure. This foundation species forms a metapopulation with variable growth characteristics in a heterogeneous environment where a strategy of phenotypic variation bestows an advantage over specialization.

Show MeSH