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Population bottleneck triggering millennial-scale morphospace shifts in endemic thermal-spring melanopsids.

Neubauer TA, Harzhauser M, Georgopoulou E, Wrozyna C - Palaeogeogr Palaeoclimatol Palaeoecol (2014)

Bottom Line: The formation of a small, highly eutrophic swamp with increased input of organic matter marginalized the melanopsids and reduced population size.The presented data make natural selection as the dominating force unlikely but rather indicates genetic drift following a bottleneck effect induced by the environmental changes.This claim contrasts the "obvious trend" and shows that great morphological variability has to be carefully and objectively evaluated in order to allow sound interpretations of the underlying mechanisms.

View Article: PubMed Central - PubMed

Affiliation: Geological-Paleontological Department, Natural History Museum Vienna, Burgring 7, 1010 Vienna, Austria.

ABSTRACT

For more than hundred years the thermal spring-fed Lake Pețea near Oradea, Romania, was studied for its highly endemic subfossil and recent fauna and flora. One point of focus was the species lineage of the melanopsid gastropod Microcolpia parreyssii, which exhibited a tremendous diversity of shapes during the earlier Holocene. As a consequence many new species, subspecies, and variety-names have been introduced over time, trying to categorize this overwhelming variability. In contrast to the varied subfossil assemblage, only a single phenotype is present today. We critically review the apparent "speciation event" implied by the taxonomy, based on the presently available information and new data from morphometric analyses of shell outlines and oxygen and carbon isotope data. This synthesis shows that one turning point in morphological evolution coincides with high accumulation of peaty deposits during a short time interval of maximally a few thousand years. The formation of a small, highly eutrophic swamp with increased input of organic matter marginalized the melanopsids and reduced population size. The presented data make natural selection as the dominating force unlikely but rather indicates genetic drift following a bottleneck effect induced by the environmental changes. This claim contrasts the "obvious trend" and shows that great morphological variability has to be carefully and objectively evaluated in order to allow sound interpretations of the underlying mechanisms.

No MeSH data available.


Shell height and width with indication of linear trend lines corresponding to the four groups. Note that M. d. acicularis (Moškanjci) and M. d. daudebartii (Vöslau) are quite well separated, while subfossil and recent Pețea-melanopsids fully overlap.
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f0015: Shell height and width with indication of linear trend lines corresponding to the four groups. Note that M. d. acicularis (Moškanjci) and M. d. daudebartii (Vöslau) are quite well separated, while subfossil and recent Pețea-melanopsids fully overlap.

Mentions: The morphological variability present in the specimens from Lake Pețea is described by three main parameters. First, differences among shell sizes of fully grown individuals (Fig. 3). Second, general shell shape, regarding slender vs. bulky, stepped vs. non-stepped, and high- vs. low-spired forms (Fig. 4). And finally, the presence, mode, and strength of sculpture, being either present as axial ribs or faint to distinct spiral keel(s) or entirely absent.


Population bottleneck triggering millennial-scale morphospace shifts in endemic thermal-spring melanopsids.

Neubauer TA, Harzhauser M, Georgopoulou E, Wrozyna C - Palaeogeogr Palaeoclimatol Palaeoecol (2014)

Shell height and width with indication of linear trend lines corresponding to the four groups. Note that M. d. acicularis (Moškanjci) and M. d. daudebartii (Vöslau) are quite well separated, while subfossil and recent Pețea-melanopsids fully overlap.
© Copyright Policy - CC BY
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4375792&req=5

f0015: Shell height and width with indication of linear trend lines corresponding to the four groups. Note that M. d. acicularis (Moškanjci) and M. d. daudebartii (Vöslau) are quite well separated, while subfossil and recent Pețea-melanopsids fully overlap.
Mentions: The morphological variability present in the specimens from Lake Pețea is described by three main parameters. First, differences among shell sizes of fully grown individuals (Fig. 3). Second, general shell shape, regarding slender vs. bulky, stepped vs. non-stepped, and high- vs. low-spired forms (Fig. 4). And finally, the presence, mode, and strength of sculpture, being either present as axial ribs or faint to distinct spiral keel(s) or entirely absent.

Bottom Line: The formation of a small, highly eutrophic swamp with increased input of organic matter marginalized the melanopsids and reduced population size.The presented data make natural selection as the dominating force unlikely but rather indicates genetic drift following a bottleneck effect induced by the environmental changes.This claim contrasts the "obvious trend" and shows that great morphological variability has to be carefully and objectively evaluated in order to allow sound interpretations of the underlying mechanisms.

View Article: PubMed Central - PubMed

Affiliation: Geological-Paleontological Department, Natural History Museum Vienna, Burgring 7, 1010 Vienna, Austria.

ABSTRACT

For more than hundred years the thermal spring-fed Lake Pețea near Oradea, Romania, was studied for its highly endemic subfossil and recent fauna and flora. One point of focus was the species lineage of the melanopsid gastropod Microcolpia parreyssii, which exhibited a tremendous diversity of shapes during the earlier Holocene. As a consequence many new species, subspecies, and variety-names have been introduced over time, trying to categorize this overwhelming variability. In contrast to the varied subfossil assemblage, only a single phenotype is present today. We critically review the apparent "speciation event" implied by the taxonomy, based on the presently available information and new data from morphometric analyses of shell outlines and oxygen and carbon isotope data. This synthesis shows that one turning point in morphological evolution coincides with high accumulation of peaty deposits during a short time interval of maximally a few thousand years. The formation of a small, highly eutrophic swamp with increased input of organic matter marginalized the melanopsids and reduced population size. The presented data make natural selection as the dominating force unlikely but rather indicates genetic drift following a bottleneck effect induced by the environmental changes. This claim contrasts the "obvious trend" and shows that great morphological variability has to be carefully and objectively evaluated in order to allow sound interpretations of the underlying mechanisms.

No MeSH data available.