Integrative taxonomy at the nexus of population divergence and speciation in insular speckled rattlesnakes

We describe two diminutive species of rattlesnakes (Genus Crotalus) from small nearshore islands off the coast of Baja California in the western Gulf of California, Mexico. In order to test the hypothesis that some island populations represent cohesive species entities, we applied linear discriminant analysis and uniform validation procedures to multiple classes of intrinsic trait data. By using previously recognised species to establish a threshold for species recognition, we found that assignment of specimens to both new species was as probable as with other established rattlesnake species within the speckled rattlesnake, Crotalus mitchellii, complex. We also found that assignment of specimens from other island populations was not as probable as for the established species, and these populations are referable to C. pyrrhus. The species endemic to Piojo Island is most closely related to other island and mainland populations of C. pyrrhus whereas the species endemic to Cabeza de Caballo Island is apparently most closely related to C. angelensis, a nearby island endemic of large body size. However, patterns from both mitochondrial and nuclear phylogenies, and phenotypic variation indicate that evolutionary trajectories of both of these species have been influenced by introgression from C. angelensis. We speculate that collective evidence based on contrasting patterns of nuclear and mitochondrial evolution supports a hybrid origin of the species from Cabeza de Caballo Island followed by exceptionally rapid mitochondrial evolution. Consistent with small body size, both species show a reduction in various scale counts relative to other species of the C. mitchellii species complex, suggesting that dwarfism is not simply a plastic response to insular conditions.

Data and Resources

Cite this as

Jesse M. Meik, Sarah Schaack, Oscar Flores-Villela, Jeffrey W. Streicher (2018). Dataset: Integrative taxonomy at the nexus of population divergence and speciation in insular speckled rattlesnakes. Natural History Museum Data Portal (data.nhm.ac.uk). https://doi.org/10.5519/0087358

Retrieved: 21:50 20 Jun 2018 (GMT)

Additional Info

Field Value
Author(s) Jesse M. Meik, Sarah Schaack, Oscar Flores-Villela, Jeffrey W. Streicher
Affiliation Tarleton State University, Reed College, Universidad Nacional Autónoma de México, The Natural History Museum
Temporal extent 2018
Dataset category Research
Last updated June 3, 2018
Last resource update June 3, 2018 (Morphological/Phenotypic data from Meik et al. (2018))
Created February 1, 2018
License Creative Commons Attribution