Speciation along a depth gradient in a marine adaptive radiation

Ingram, Travis

doi:10.1098/rspb.2010.1127

Cited by 141 publications

(186 citation statements)

References 41 publications

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“…More recent theoretical models, however, show that frequency-dependent selection due to local competition in trait space and physical space naturally results in discrete clustering of an adaptive trait along a continuous environmental gradient: these models demonstrate the plausibility of evolutionary branching under such ecological conditions in asexual populations (Mizera and Meszéna 2003;Leimar et al 2008), as well as the evolution of reproductive isolation in sexual populations (e.g., Doebeli and Dieckmann 2003;Heinz et al 2009). Interestingly, empirical evidence for the maintenance and emergence of adaptive divergence along environmental gradients is accumulating, in particular relating to depth gradients of aquatic environments (Vonlanthen et al 2009;Ingram 2011). The results presented here support the theory of ecologically based adaptive diversifications along environmental gradients.…”

Section: Discussionsupporting

confidence: 73%

Adaptive Phenotypic Diversification along a Temperature-Depth Gradient

Ohlberger

Brännström

Dieckmann

2013

The American Naturalist

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Adaptive phenotypic diversification along a temperature-depth gradient. Online enhancements: appendixes.abstract: Theoretical models suggest that sympatric speciation along environmental gradients might be common in nature. Here we present the first data-based model of evolutionary diversification along a continuous environmental gradient. On the basis of genetic analyses, it has been suggested that a pair of coregonid fishes (Coregonus spp.) in a postglacial German lake originated by sympatric speciation. Within this lake, the two species segregate vertically and show metabolic adaptations to, as well as behavioral preferences for, correspondingly different temperatures. We test the plausibility of the hypothesis that this diversifying process has been driven by adaptations to different thermal microhabitats along the lake's temperature-depth gradient. Using an adaptive-dynamics model that is calibrated with empirical data and allows the gradual evolution of a quantitative trait describing optimal foraging temperature, we show that under the specific environmental conditions in the lake, evolutionary branching of a hypothetical ancestral population into two distinct phenotypes may have occurred. We also show that the resultant evolutionary diversification yields two stably coexisting populations with trait values and depth distributions that are in agreement with those currently observed in the lake. We conclude that divergent thermal adaptations along the temperature-depth gradient might have brought about the two species observed today.

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Section: Discussionsupporting

confidence: 73%

Adaptive Phenotypic Diversification along a Temperature-Depth Gradient

Ohlberger

Brännström

Dieckmann

2013

The American Naturalist

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“…This result was somewhat surprising because intraspecific morphological variation is not well documented and often not anticipated among marine fishes. One reason that it is not anticipated in marine systems is that it is assumed that there are fewer barriers to gene flow than in freshwater systems [31,32]. Without physical barriers to gene flow there is less opportunity for local adaptation to occur which could result in more homogenous populations.…”

Section: Discussionmentioning

confidence: 99%

Intraspecific Morphological Variation in Two Common Marine Fish Species from South Africa

Mattson

Belk

2013

TOFISHSJ

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Intraspecific morphological variation in fish is typically associated with sexual dimorphism, or one of three common environmental gradients: variation in intensity of predation, variation in water velocity, or variation in feeding niche. The preponderance of examples of environment-associated morphological variation within fish species has been documented in freshwater systems. It is not clear whether environment-associated intraspecific morphological variation is less common in marine fishes or whether there has just been a lack of investigation. We used geometric morphometric analysis to quantify shape variation in two species of South African marine fish commonly harvested for human consumption, Pterogymnus laniarius (panga), and Argyrosomus inodorus (silver kob). Neither species exhibited significant sexual dimorphism, but both species exhibited significant intraspecific morphological variation. This variation appears consistent with patterns expected from variation along the benthic-pelagic feeding niche continuum.

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“…Depth gradients in light are hypothesized as a cause of speciation by sensory drive in cichlids (37) and factors associated with depth appear to have driven speciation in rockfish (38). Among marine sibling species reported by Knowlton (17), over one-half involved depth as a dividing factor, even though not all comparisons included depth.…”

Section: Discussionmentioning

confidence: 99%

Long prereproductive selection and divergence by depth in a Caribbean candelabrum coral

Prada

Hellberg

2013

Proc. Natl. Acad. Sci. U.S.A.

136

197

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Long-lived corals, the foundation of modern reefs, often follow ecological gradients, so that populations or sister species segregate by habitat. Adaptive divergence maintains sympatric congeners after secondary contact or may even generate species by natural selection in the face of gene flow. Such ecological divergence, initially between alternative phenotypes within populations, may be aided by immigrant inviability, especially when a long period separates larval dispersal and the onset of reproduction, during which selection can sort lineages to match different habitats. Here, we evaluate the strength of one ecological factor (depth) to isolate populations by comparing the genes and morphologies of pairs of depth-segregated populations of the candelabrum coral Eunicea flexuosa across the Caribbean. Eunicea is endemic to the Caribbean and all sister species co-occur. Eunicea flexuosa is widespread both geographically and across reef habitats. Our genetic analysis revealed two depth-segregated lineages. Field survivorship data, combined with estimates of selection coefficients based on transplant experiments, suggest that selection is strong enough to segregate these two lineages. Genetic exchange between the Shallow and Deep lineages occurred either immediately after divergence or the two have diverged with gene flow. Migration occurs asymmetrically from the Shallow to Deep lineage. Limited recruitment to reproductive age, even under weak annual selection advantage, is sufficient to generate habitat segregation because of the cumulative prolonged prereproductive selection. Ecological factors associated with depth can act as filters generating strong barriers to gene flow, altering morphologies, and contributing to the potential for speciation in the sea.

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Speciation along a depth gradient in a marine adaptive radiation

Cited by 141 publications

References 41 publications

Adaptive Phenotypic Diversification along a Temperature-Depth Gradient

Adaptive Phenotypic Diversification along a Temperature-Depth Gradient

Intraspecific Morphological Variation in Two Common Marine Fish Species from South Africa

Long prereproductive selection and divergence by depth in a Caribbean candelabrum coral

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