Demographic Assessment of the Triploid Parthenogenetic Lizard Aspidoscelis Neotesselatus at the Northern Edge of its Range

Abstract

Aspidoscelis neotesselatus (Colorado Checkered Whiptail) is a hybrid-derived triploid parthenogenetic lizard with a natural range overlapping with six counties in southeastern Colorado, USA. It has also become established by anthropogenic causation in Grant County, Washington State, approximately 1,600 km northwest of its range in Colorado. Large parts of its natural range are within military reservations. Reduced genetic variation in all-female species makes them especially susceptible to environmental disturbances, such as military activities. At Fort Carson (FC), we estimated an abundance index via a catch-per-unit estimator, weekly survival using Cormack-Jolly-Seber models, and body condition and clutch size as indicators of population health across three low-impact training areas (TA; 45, 48, and 55). Abundance estimates varied across TAs from a low of 0.99 to a high of 6.12 females per hectare. Body condition only marginally varied by age class and TAs. Apparent monthly survival was relatively low in all areas and even lower at TA 55 than at TA 48 (0.638 versus 0.771); however, the uncertainty around those estimates was large. Results suggest that TA 48 supported a large fraction of reproductive females that were successful in producing eggs, providing further insight into where monitoring and conservation efforts should be concentrated within FC

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