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Evolution underground: shedding light on the diversification of subterranean insects.

Juan C, Emerson BC - J. Biol. (2010)

Bottom Line: A recent study in BMC Evolutionary Biology has reconstructed the molecular phylogeny of a large Mediterranean cave-dwelling beetle clade, revealing an ancient origin and strong geographic structuring.It seems likely that diversification of this clade in the Oligocene was seeded by an ancestor already adapted to subterranean life.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department de Biologia, Universitat de les Illes Balears, 07122 Palma de Mallorca, Spain. cjuan@uib.es

ABSTRACT
A recent study in BMC Evolutionary Biology has reconstructed the molecular phylogeny of a large Mediterranean cave-dwelling beetle clade, revealing an ancient origin and strong geographic structuring. It seems likely that diversification of this clade in the Oligocene was seeded by an ancestor already adapted to subterranean life.

Show MeSH
Speciation models in subterranean taxa. Schematic diagram of (a) the 'climatic relict' and (b) the 'adaptive shift' hypotheses. In the former, a broadly distributed surface species that has exaptations (pre-adaptations) to the underground environment invades the caves. The underground population remains in contact with the surface population, limiting genetic divergence of the two. Climatic oscillations cause local extinction of surface populations, whereas surviving populations remain in the underground. The predictions from this for geographic distribution are that either only relict cave-dwelling lineages survive, or surface populations are strictly allopatric and geographically remote with respect to the underground. Over time, cave populations differentiate, developing troglomorphic characters and become reciprocally monophyletic. In the adaptive shift hypothesis caves are invaded by surface populations, exploiting new resources with the establishment of differential selection pressures in the epigean and underground environments. Speciation is driven by divergent selection accompanied by a reduction of gene flow. In this case, surface and cave species are expected to have parapatric distributions, at least during the initial phases of the process. Ellipses represent geographic distributions of populations. Troglobite is the term given to animals that have become adapted to dwell in cave environments and that cannot survive outside such environments. Diagram modified from Figures 1 and 2 in [2].
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Figure 2: Speciation models in subterranean taxa. Schematic diagram of (a) the 'climatic relict' and (b) the 'adaptive shift' hypotheses. In the former, a broadly distributed surface species that has exaptations (pre-adaptations) to the underground environment invades the caves. The underground population remains in contact with the surface population, limiting genetic divergence of the two. Climatic oscillations cause local extinction of surface populations, whereas surviving populations remain in the underground. The predictions from this for geographic distribution are that either only relict cave-dwelling lineages survive, or surface populations are strictly allopatric and geographically remote with respect to the underground. Over time, cave populations differentiate, developing troglomorphic characters and become reciprocally monophyletic. In the adaptive shift hypothesis caves are invaded by surface populations, exploiting new resources with the establishment of differential selection pressures in the epigean and underground environments. Speciation is driven by divergent selection accompanied by a reduction of gene flow. In this case, surface and cave species are expected to have parapatric distributions, at least during the initial phases of the process. Ellipses represent geographic distributions of populations. Troglobite is the term given to animals that have become adapted to dwell in cave environments and that cannot survive outside such environments. Diagram modified from Figures 1 and 2 in [2].

Mentions: The geographic distributions and phylogenetic relationships of surface taxa and related subterranean taxa can help to distinguish between the two key hypotheses of origin; the parapatric (termed in the specialized literature the 'adaptive shift hypothesis') and allopatric (the 'climatic relict hypothesis') models (Figure 2; [2,3,6] and references therein). Parapatric describes the situation where two species or distinct populations of the same species overlap to a limited extent, while allopatric describes the situation where species or populations have mutually exclusive distributions.


Evolution underground: shedding light on the diversification of subterranean insects.

Juan C, Emerson BC - J. Biol. (2010)

Speciation models in subterranean taxa. Schematic diagram of (a) the 'climatic relict' and (b) the 'adaptive shift' hypotheses. In the former, a broadly distributed surface species that has exaptations (pre-adaptations) to the underground environment invades the caves. The underground population remains in contact with the surface population, limiting genetic divergence of the two. Climatic oscillations cause local extinction of surface populations, whereas surviving populations remain in the underground. The predictions from this for geographic distribution are that either only relict cave-dwelling lineages survive, or surface populations are strictly allopatric and geographically remote with respect to the underground. Over time, cave populations differentiate, developing troglomorphic characters and become reciprocally monophyletic. In the adaptive shift hypothesis caves are invaded by surface populations, exploiting new resources with the establishment of differential selection pressures in the epigean and underground environments. Speciation is driven by divergent selection accompanied by a reduction of gene flow. In this case, surface and cave species are expected to have parapatric distributions, at least during the initial phases of the process. Ellipses represent geographic distributions of populations. Troglobite is the term given to animals that have become adapted to dwell in cave environments and that cannot survive outside such environments. Diagram modified from Figures 1 and 2 in [2].
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2871511&req=5

Figure 2: Speciation models in subterranean taxa. Schematic diagram of (a) the 'climatic relict' and (b) the 'adaptive shift' hypotheses. In the former, a broadly distributed surface species that has exaptations (pre-adaptations) to the underground environment invades the caves. The underground population remains in contact with the surface population, limiting genetic divergence of the two. Climatic oscillations cause local extinction of surface populations, whereas surviving populations remain in the underground. The predictions from this for geographic distribution are that either only relict cave-dwelling lineages survive, or surface populations are strictly allopatric and geographically remote with respect to the underground. Over time, cave populations differentiate, developing troglomorphic characters and become reciprocally monophyletic. In the adaptive shift hypothesis caves are invaded by surface populations, exploiting new resources with the establishment of differential selection pressures in the epigean and underground environments. Speciation is driven by divergent selection accompanied by a reduction of gene flow. In this case, surface and cave species are expected to have parapatric distributions, at least during the initial phases of the process. Ellipses represent geographic distributions of populations. Troglobite is the term given to animals that have become adapted to dwell in cave environments and that cannot survive outside such environments. Diagram modified from Figures 1 and 2 in [2].
Mentions: The geographic distributions and phylogenetic relationships of surface taxa and related subterranean taxa can help to distinguish between the two key hypotheses of origin; the parapatric (termed in the specialized literature the 'adaptive shift hypothesis') and allopatric (the 'climatic relict hypothesis') models (Figure 2; [2,3,6] and references therein). Parapatric describes the situation where two species or distinct populations of the same species overlap to a limited extent, while allopatric describes the situation where species or populations have mutually exclusive distributions.

Bottom Line: A recent study in BMC Evolutionary Biology has reconstructed the molecular phylogeny of a large Mediterranean cave-dwelling beetle clade, revealing an ancient origin and strong geographic structuring.It seems likely that diversification of this clade in the Oligocene was seeded by an ancestor already adapted to subterranean life.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department de Biologia, Universitat de les Illes Balears, 07122 Palma de Mallorca, Spain. cjuan@uib.es

ABSTRACT
A recent study in BMC Evolutionary Biology has reconstructed the molecular phylogeny of a large Mediterranean cave-dwelling beetle clade, revealing an ancient origin and strong geographic structuring. It seems likely that diversification of this clade in the Oligocene was seeded by an ancestor already adapted to subterranean life.

Show MeSH