Causes for their evolution remain a matter of speculation, but a functional coupling to the evolution of the ability to enrol is one possible factor.
In a comparative study of anthropogenic causes for contemporary evolution, harvesting was found to result in quicker evolutionary change than other human influences (Darimont et al. 2009).
With all the advantages that have established Daphnia as model organisms, including a sophisticated genetic background [ 63], we hope that this study provides an experimental basis for future research and further insight into the ultimate causes for the evolution of inducible defenses.
Such intermediate selfing rates are not expected under classic population genetic models, which posit that the evolution of inbreeding depression generated by deleterious recessive alleles is the cause for the evolution of different reproduction modes [ 1, 3, 9].
In spite of an ancient human occupation, a mainly natural cause for the evolution of the lagoon appears most likely.
The quick decrease of available gametes in a turbulent environment is proposed as ultimate cause for the evolution of many but short-lived sperm and quick fertilization.
Vegetation cover may determine which colours are cryptic and which ones are conspicuous, and thus, background matching to avoid predation may be the cause for the evolution of colour differences [ 44, 45].
Moreover, ultrasound studies showed that not only in erosive but also in non-erosive joints in EOA more power Doppler signal and effusion is seen in comparison to joints in non-erosive hand OA, suggesting an underlying cause for erosive evolution.
These results are consistent with a putative function in species recognition, but further analyses of protein function and sequence variation in species with different breeding systems are necessary to reveal the underlying causes for the rapid evolution of oleopollenins.
