Thermal Ecophysiology and Vulnerability to Global Climate Change in a Population of Phrynosoma sherb

Santos-Bibiano, Rufino

Arenas-Moreno, Diego Miguel

Posgrado en Ciencias Biológicas

Instituto de Biología

Universidad Nacional Autónoma de México

Ciudad de México, México

rufino.santos@yaho.com.mx

Laboratorio de Herpetología

Departamento de Zoología

Instituto de Biología

Universidad Nacional Autónoma de México

Ciudad de México, México

Mendez de la Cruz, Fausto R.

Laboratorio de Herpetología

Departamento de Zoología

Instituto de Biología

Universidad Nacional Autónoma de México

Ciudad de México, México

The increase in temperature due to global climate change has several negative effects on many organisms, mainly ectotherms. However, organisms can mitigate these changes through physiological or behavioral adjustments, and even migrate to higher elevations or sites with suitable thermal qualities. Therefore, our objective was determine several thermal parameters and one physiological of a population of Phrynosoma sherbrookei located in the altitudinal limit, based on the above parameters we evaluated the extinction risk of the species. During January-October/2016 and January-April/2017 we collected 131 individuals (males, non-gravid, and gravid female), among these categories the Tb and Tset were similar. The organisms are accurate for thermoregulation (db= 3.5) although the thermal quality varies between the dry and rainy seasons (de= 6.1 vs. 7.8), resulting in thermoregulatory efficiencies influenced by temporality. The minimum and maximum critical temperatures (CTmin ~ 12° C and CTmax ~ 43.5° C) were similar to other clade species. At the study site we recorded operating temperatures (Te) below the CTmin during the night and early morning in both seasons limiting the activity of the organisms during this time, while during the dry season the Te usually exceed the CTmax during the period of activity, potentially reducing it by four hours. The running speed is influenced by the temperature, when contrasting the evaluated categories we only found significant differences in two of the six treatments, being the gravid females slower in relation to their congeners, which can be attributed to the pregnancy. Finally, extinction risk models determined a high vulnerability in a large part of their geographical distribution, it should be noted that our population located in the altitudinal limit could not migrate to higher elevations. In this sense one of the possible responses of the organisms would be physiologically modify various thermal parameters.


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