Sharing the Resource: Six Species of Rattlesnakes in Joshua Tree National Park, California

The competitive exclusion principle would seem to apply to six species of rattlesnakes in the genus Crotalus, all of which feed mostly on small mammals. In Joshua Tree National Park, California, however, six species occur in an area of just 400,000 ha. A pattern noted in ecology is that diversity at one level begets diversity at other levels. Almost 70 years of locality data combined with present field research was used as evidence for the hypothesis that these rattlesnake species mostly avoid competitive exclusion by microhabitat differences within the great diversity of ecological communities in the park. These long-term records might also indicate that the dynamics of the desert ecosystem could be changing, possibly the result of climate change and/or local urbanization

Sharing the Resource: Six Species of Rattlesnakes in Joshua Tree National Park, California

The competitive exclusion principle would seem to apply to six species of rattlesnakes in the genus Crotalus, all of which feed mostly on small mammals. In Joshua Tree National Park, California, however, six species occur in an area of just 400,000 ha. A pattern noted in ecology is that diversity at one level begets diversity at other levels. Almost 70 years of locality data combined with present field research was used as evidence for the hypothesis that these rattlesnake species mostly avoid competitive exclusion by microhabitat differences within the great diversity of ecological communities in the park. These long-term records might also indicate that the dynamics of the desert ecosystem could be changing, possibly the result of climate change and/or local urbanization

Genome-wide analysis identifies 12 loci influencing human reproductive behavior.

The genetic architecture of human reproductive behavior-age at first birth (AFB) and number of children ever born (NEB)-has a strong relationship with fitness, human development, infertility and risk of neuropsychiatric disorders. However, very few genetic loci have been identified, and the underlying mechanisms of AFB and NEB are poorly understood. We report a large genome-wide association study of both sexes including 251,151 individuals for AFB and 343,072 individuals for NEB. We identified 12 independent loci that are significantly associated with AFB and/or NEB in a SNP-based genome-wide association study and 4 additional loci associated in a gene-based effort. These loci harbor genes that are likely to have a role, either directly or by affecting non-local gene expression, in human reproduction and infertility, thereby increasing understanding of these complex traits