Geographic isolation, genetic divergence, and ecological non-exchangeability define ESUs in a threatened sky-island rattlesnake

Molecular and phenotypic diversity in Chionactis occipitalis (Western Shovel-nosed Snake), with emphasis on the status of C. o. klauberi (Tucson Shovel-nosed Snake).

“…The prominent idea to prioritizing units for protection has been the concept of the evolutionary significant unit (ESU; Ryder 1986). However, the nature and criteria used to delineate ESUs has been increasingly controversial, and recent discussions have even challenged the dichotomous nature inherent in designating ESUs given the continuum through which populations evolve Goldstein et al 2000;Fraser and Bernatchez 2001;Holycross and Douglas 2007). Therefore, in taking the first steps to characterize units of conservation within C. occipitalis, we focus on identifying population segments that show evidence of long-term evolutionary history based on our genetic data.…”

DNA Markers Indicate Low Genetic Diversity and High Genetic Divergence in the Landlocked Freshwater Goby, Rhinogobius sp. YB, in the Ryukyu Archipelago, Japan

“…The framework we have presented here could aid in the identification and conservation of vulnerable insular taxa. Our framework may also be useful for delineating intraspecific conservation units for mainland taxa that inhabit "habitat islands" that are susceptible to the same genetic and demographic threats as true islands (Knowles 2001, Holycross and Douglas 2007, Bech et al 2009). Ultimately, we believe that given limited conservation funding, knowledge of adaptive differentiation is essential for developing sound conservation strategies, particularly for geographically isolated populations.…”

Amphibians and Reptiles of the Madrean Archipelago of Arizona and New Mexico

“…A number of species found in the archipelago have been included in studies of DNA phylogeography, e.g., the Ambystoma tigrinum complex (see Shaffer and McKnight, 1996), Anaxyrus punctatus (see Bryson et al, 2012a), Craugastor augusti (see Goldberg et al, 2004a), Gastrophryne mazatlanensis (see Streicher et al, 2012), Hyla arenicolor (see Bryson et al, 2010;Klymus and Gerhardt, 2012), Hyla wrightorum (see Gergus et al, 2004), Lithobates chiricahuensis (see Goldberg et al, 2004b), Phrynosoma hernandesi (see Zamudio et al, 1997), Sceloporus slevini (see Bryson et al, 2012b), the Sceloporus undulatus complex (see Leaché and Reeder, 2002), Sceloporus virgatus (see Tennessen and Zamudio, 2008), Xantusia bezyi (see Sinclair et al, 2004), Crotalus cerberus (see Douglas et al, 2006); Crotalus willardi (see Holycross and Douglas, 2007); Lampropeltis pyromelana (see Burbrink et al, 2011), and Thamnophis rufipunctatus (see Wood et al, 2011). in the majority of these studies, the mountain ranges in the archipelago were too sparsely sampled to evaluate the potential of the gene segments and populations to shed light on the historical biogeography of the region.…”

“…The study also highlights ranges that remain poorly sampled and for which additional field work is needed. We hope this paper will stimulate thorough sampling of populations within the Madrean region for phylogeographic analyses of DNA sequences that may identify repeated phylogenetic patterns within the archipelago (e.g., Barber, 1999;Leaché and Reeder, 2002;Holycross and Douglas, 2007;Tennessen and Zamudio 2008;Burbrink et al, 2011).…”