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

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