By Patricia Galina, Rafael A. Lara, Jorge H. Valdez and Fausto R. Méndez
Climate change effects are reflected in the increase of air and ocean temperatures, changes in the frequency and intensity of hurricanes, and other extreme climate events are phenomena documented for the effects inflicted on living organisms (IPCC, 2013).
Ectotherms (for example, insects or reptiles) have been the most affected for their direct dependence from environmental temperatures (Huey et al., 2013). Several studies have focused on explaining the mechanisms that have affected amphibians and reptiles because of the evident decline or disappearance of their populations (Sinervo et al., 2010; Wake and Vredenburg, 2008; Winter et al., 2016).
Reptiles need to obtain heat to carry out their vital biological processes (feeding, digestion and reproduction) by exposing themselves directly to sun rays or being in contact with the surrounding objects. Therefore, any alteration in the environmental temperature affects their activity hours, physiological performance, behavior, distribution and reproduction. (Sinervo, 2010).
Also, if we take into consideration other current environmental problems such as habitat modification, vegetation loss and, consequently, the reduction of shadow and refuge availability, perch and nesting sites, reptiles are targeted for sudden local extinction of their populations due to the alterations of their thermic environments.
The vulnerability degree of the species will depend on their life history characteristics, for example, the time of the year in which they reproduce, reproduction mode (oviparous or viviparous), habits (diurnal, nocturnal, arboreal, terrestrial, etc.), the types of environment they inhabit and temperature sensitivity.
For example, species with temperature-dependent sex determination, like tortoises, crocodiles and some lizards are vulnerable because of the temperature’s effect on the sex ratio of the population, as the incubation temperature determines whether females or males are born. Another example are those species that depend on particular environment conditions, either humidity, water availability, or species linked to extreme places such as the desert which, besides the thermal fluctuations, can be severely affected by prolonged droughts (Westphal et al., 2016).
Due to the necessity of this information in Mexico, the project “Climate change effects on reptiles in northwestern Mexico: conservation and mitigation measures” begins and is financed by the National Commission of Science and Technology (in Spanish: CONACYT) and the Northwestern Center of Biological Research (in Spanish: CIBNOR), with the participation of researchers, technicians and students from several institutions.
The objective of the project is to study the thermal ecology of different reptile species who have adapted to diverse environments and have various reproduction types, this will allow to understand and evaluate their vulnerability to climate change, as well as to look out for management strategies to conserve and maintain the ideal habitats for wildlife populations besides the thermal refuge areas.
This study about thermal ecology in the first instance, consists in learning the species’ body temperatures (taken in field ) and preferred temperatures under controlled laboratory conditions (taken in a temperature gradient). It also consists in monitoring the environmental temperature for long periods with temperature sensors (data-loggers) connected to models that emulate reptiles, which are located in the microhabitats occupied by the organisms.
All this information from the organism’s perspective (requirements) and habitat (offer), together with the species distribution will be integrated in predictive models under different climate change scenarios to evaluate their vulnerability and to finally propose conservation measures to mitigate it and to define zones that can function as thermal refuges.
Some of the selected sites are found within natural protected areas like the Punta Mazo Nature Reserve, which presents a particular habitat (coastal dunes) and it is an important conservation zone of a microendemic species (of restricted distribution) the Baja California legless lizard (Anniella geronimensis), a viviparous species with snake-appearance that lives in the sand. This lizard is considered microendemic and highly vulnerable because it is distributed only in a coastal dune strip of approximately 54 miles, from Colonia Guerrero to Punta Baja, in the northwest of Baja California (Analis-García and Valdez-Villavicencio, 2008). Punta Mazo is also an excellent place to study other species, such as the Cedros Island horned lizard (Phrynosoma cerroense), the common side-blotched lizard (Uta stansburiana) and the Baja California spiny lizard (Sceloporus zosteromus), which is mainly found in the volcanic rock area.
Besides the beauty of its coastal dunes and volcanic areas, the Punta Mazo Nature Reserve is important for being a shelter for species of biological relevance, which we still do not know much of their ecology and evolution; therefore, the preservation of this reserve in Baja California is highly appreciated.
We thank the nature reserve’s staff, especially Enrique Alfaro, for his valuable support during our staying; to our colleague Abelino Cota and to the students Yaredh Ramírez, Isaí Valle, Ana Pérez, Saúl Domínguez, Diego Arenas, Fabiola Gandarilla and Christian Valdez for their company and invaluable contribution to this project.
About the authors
Patricia Galina Tessaro
Biology graduate from Universidad Autonoma Metropolitana, with a Master’s Degree in Sciences from the Autonomous University of Mexico (UNAM in Spanish) and a doctorate from the Northwestern Center of Biological Research (in Spanish: CIBNOR). She has collaborated in several projects focused on fauna, particularly reptiles and amphibians of the Baja California peninsula. She is currently responsible for the “Climate change effects on reptiles” project, working in the Environmental Planning and Conservation Program of the Northwestern Center of Biological Research in La Paz, Baja California Sur.
Email: pgalina04@cibnor.mx
Rafael A. Lara Reséndiz
He concluded his bachelor’s degree, master’s and doctorate in Biological Sciences in the Autonomous University of Mexico. He is currently doing a post doctorate in the University of California, Santa Cruz with the project “Thermal ecology and extinction risk of amphibians and reptiles in the northwest of Mexico and southwest of the United States.” He is interested in the study of thermoregulatory mechanisms and the way herpetofauna interacts with its biotic and abiotic environment, as well as the ecological effects climate change has on herpetofauna. He is renowned in the SNI (Mexican National System of Researchers) as level I.
Email: rafas.lara@gmail.com
Jorge H. Valdez Villavicencio
Biologist from the Autonomous University of Baja California (in Spanish: UABC), he concluded his master’s degree in the Northwestern Center of Biological Research in La Paz, Baja California Sur. He is interested in amphibian and reptile diversity, ecology and conservation in the northwest of Mexico, mainly the Baja California peninsula and Sonora. He is an associated curator of the Herpetological collection of the Science Faculty of UABC and is currently the Project Coordinator and founding member of the non-profit organization “Conservación de Fauna del Noroeste.”
Email: j_h_valdez@yahoo.com.mx
Fausto R. Méndez de la Cruz
He studied his bachelor’s, master’s and doctorate degrees in Biological Sciences at UNAM. He is a C-level researcher in the Biology Institute of UNAM. Currently, his researches are focused in viviparity evolution and lizard parthenogenesis; his most recent is about amphibian and reptile vulnerability in face of climate change in North and South America. He is recognized with a II level in the SNI.
Email: faustomendez6@gmail.com
References
- Alaniz-García, J. and Valdez-Villavicencio, J. H. (2008). Anniella geronimensis data sheet. In: Alaniz-García, J. (compiler). Actualización de las fichas de información para los reptiles incluidos en la Norma Oficial Mexicana-059-SEMARNAT-2001, para Baja California. Vertebrae Laboratory, Faculty of Sciences, Autonomous University of Baja California. SNIB-CONABIO Data base. Project No. CK013. México, D.F
- Bickford, D., Howard, S.D., Ng, D.J.J., Sheridan, J. A. (2010). Impacts of climate change on the amphibians and reptiles of Southeast Asia. Biodiversity and Conservation, 19:1043-1062
- Huey, R.B., Kearney, M. R., Krockenberger, A., Holtum, J.A.M., Jess, M.y Williams, S.E. (2012). Predicting organismal vulnerability to climate warming: roles of behavior, physiology and adaptation. Philosophical Transactions of the Royal Society 367:1665-1679.
- IPCC (Intergovernmental Panel on Climate Change). (2013). Sumary for Policymarkers. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Naeuels, Y. Xia, V. Bex and P.M Midgley (eds)]. Cambridge University Press, Cambridge, United Kingdom and New York, USA.
- Sinervo, B. et al. (2010). Erosion of Lizard Diversity by Climate Change and altered thermal niches. Science, 328: 894-899.
- Wake, D.B. and Vredenburg, V.T. (2008). Are we in the midst of the sixth mass extinction? A view from the world of amphibians. Proceedings of the National Academy of Sciences, 105: 11466-11473.
- Westphal, M.F., Stewart, J.A.E., Tennant, E.N., Butterfield, H.S. and Sinervo, B. (2016). Contemporary drought and future effects of climate change on the endangered blunt-nosed leopard lizard, Gambelia sila. Plos One, 11: e0154838.
- Winter, M., Fiedler W., Hochchka, W.M., Koehncke A., Meiri S., De la Riva. (2016). Patterns and biases in climate change research on amphibians and reptiles: a systematic review. Royal Society Open Science, 3:160158.