However, the ecology of some Arctaphaenops species, able to live at high altitude in cold, ice caves [ 55], contributes to weaken this hypothesis of an extinction by glacial episodes, not supported by our phylogeny.
Unfortunately, the hypothesis of ephialtitid extinction caused by changes in the food plants of their insect hosts, even though attractive is not consistent, with the geochronological aspect of the fossil record.
Biotic assessments are increasingly carried out to detect NIS (Gravili et al. 2013; Katsanevakis et al. 2013), and might be used also for the purpose of testing hypotheses of putative extinctions.
Therefore our results favour the hypothesis of few and sudden extinction events.
Three main hypotheses, corresponding to different patterns of extinction, have been proposed [ 18].
These population-level processes, together with ENSO should have produced increases in local diversity; however, while our results do not support this hypothesis, they do support the ENSO hypothesis as a cause of extinctions and low diversity in the zone.
We employ a simple null hypothesis [see [ 7]] for testing the threat of extinction from Muller's ratchet in the unisexual fish Poecilia formosa, the Amazon molly.
Our hypothesis is that the embryos of amphibian species at risk of extinction could be cryopreserved by vitrification, using methods which have proved successful with fish oocyte.
This means there is not much support for the hypothesis of a food shortage and their extinction still remains somewhat of a mystery.
Consistent with this hypothesis, administration of AM404 prior to 30-trial extinction training led to an enhancement of extinction retention, as AM404 animals showed significantly less fear in the presence of the CS 24 h following extinction training (Figure 3a, main effect of drug treatment F 1,70)=4.06, p<0.05).
