The adhesions are filamentous or fibrous attachments that bind the sigmoid colon to the pelvic sidewall tight enough to alter the course of the colon, sometimes causing a slight narrowing or kink that creates a bottleneck effect
, explained Dr.
The main threats to the species are: isolation of populations (this causes a bottleneck effect
and increases the vulnerability of the populations); habitat degradation and water removal; the effects of climate change; the spread of invasive species (Orconectes limosus and Procambarus clarkii); and poaching and lack of knowledge of the species among local populations.
(1982) that this work is irrelevant to sexual speciation processes because it used parthenogenesis to induce an extreme bottleneck effect
. Much of this uneasiness about parthenogenesis is based upon some fundamental misconceptions about parthenogenesis in Drosophila and its genetic consequences.
To obtain a better picture of the evolutionary relationship between Lab and the other' populations before the bottlenecks, we have made a correction for bottleneck effect
(Chakraborty and Nei 1977).