This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.įunding: Arizona State University, Zoo Atlanta, Georgia State University, San Diego State University, and David L. Received: NovemAccepted: JanuPublished: March 5, 2014Ĭopyright: © 2014 Clark et al. PLoS ONE 9(3):Įditor: Marco Festa-Bianchet, Université de Sherbrooke, Canada atrox, and we thus urge more widespread adoption of molecular tools by field researchers studying the mating systems and sexual selection of snakes and other secretive taxa.Ĭitation: Clark RW, Schuett GW, Repp RA, Amarello M, Smith CF, Herrmann H-W (2014) Mating Systems, Reproductive Success, and Sexual Selection in Secretive Species: A Case Study of the Western Diamond-Backed Rattlesnake, Crotalus atrox. Overall, our field observations alone would have been insufficient to quantitatively measure the mating system of this population of C. Moreover, the spatial proximity of males to mothers was significantly associated with reproductive success. Larger males did not father significantly more offspring, but we found evidence for size-specific male-mating strategies, with larger males guarding females for longer periods in the mating seasons. We detected high levels of multiple paternity within litters, yet found little concordance between paternity and observations of courtship and mating behavior. Specifically, we used microsatellite markers to genotype 299 individuals, including neonates from litters of focal females to ascertain parentage using full-pedigree likelihood methods. Here, we used molecular genetic techniques in a 10-year radio-telemetric investigation of the western diamond-backed rattlesnake ( Crotalus atrox) for an analysis of its mating system and to measure sexual selection. Even though molecular genetic tools are particularly valuable for species that are difficult to observe directly, they have not been widely adopted. Such field studies can benefit greatly from integrating the methods of molecular genetics with traditional approaches. The sedimentation coincides with intensified uplift of the Patagonian Andes during the ‘Quechua Phase’ of Andean tectonism, which is reflected by a change in paleocurrent directions from northwest to east-northeast.Long-term studies of individual animals in nature contribute disproportionately to our understanding of the principles of ecology and evolution. A measured lithostratigraphic column is presented and the depositional environment is interpreted as a coastal plain with small, meandering rivers and ephemeral floodplain lakes. Similar ages have been obtained from the basal part of the Santa Cruz Formation at Estancia Quién Sabe in southwestern Argentina, supporting the assumption of a regional continuity between these deposits.
The lithological correlation is also confirmed by detrital zircon ages (maximum age of 18.23☐.26 Ma) and a rich assemblage of terrestrial vertebrate fossils, biostratigraphically equivalent to a post-Colhuehuapian, pre-Santacrucian South American Land Mammal Age (SALMA) fauna, suggesting a range of 19 to 17.8 Ma. These include the Estancia 25 de Mayo Formation and the basal part of the Santa Cruz Formation. In this brief contribution the main progresses in the above mentioned subjects are summarized.Ī succession of marine and continental strata on the southern flank of Cerro Cono in the Sierra Baguales, northeast of Torres del Paine, can be correlated with stratigraphic units exposed along the southern border of the Lago Argentino region in Santa Cruz Province, Argentina. Geologic, radiometric and magnetostratigraphic studies helped improving the calibration of land-mammal bearing horizons and correlation among basins. On this basis, many phylogenetic, paleobiogeographic, paleobiologic, and taphonomic studies could be carried out. The discovery of new land-mammal bearing localities outside the classical Patagonia, like those from the northwest and central Argentina, and the Antarctic Peninsula, provided a large number of fossils that allowed the recognition of new taxa.
The interest of paleontologists in these subjects is reflected in the publication of numerous articles with different approaches. Among them, the efforts focused in prospecting new localities, the increasing amount of researchers and the application of new techniques are the most important. In the last 50 years, several causes contributed to increase the knowledge of Paleogene continental mammals in Argentina. PALEOGENE CONTINENTAL MAMMALS FROM ARGENTINA: THE LAST FIFTY YEARS OF INVESTIGATIONS.
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