**2.2.1 Physiological performance in reptiles and climate change**

There are proposals that combine the spatial and temporal variation with the physiological (speed and strength) and morphological traits (shape of limbs) ecologically relevant. For example, in the *Urosaurus ornatus* lizard has been measured the speed and endurance of various populations, as well as the shape and size of their limbs through the altitudinal range where lizards are distributed. This lizard exhibit significant variation in the shape of his limbs corresponding to available perch types for each population, speed, and endurance. Thus the possible change in habitat structure and thermal regimes could result in an alteration of development patterns of lizards and cause changes in body shape and size of adults and in the way they use their habitat, behavior strategies, and physiological performance. Under this scenario only some population would be at risk, even though their evolutionary responses are consider slower compared with the speed of environmental change (Miles, 1994). On the other hand, long-term experimental studies with young *Notechis scutatus* snakes in enclosures with cold (19-22°C), intermediate (19-26°C), and hot (19-37°C) thermal gradients, suggested that these snakes compensated restricted thermal opportunities, although behavioral plasticity depending on thermal environment experienced to birth, therefore these conditions influenced subsequent thermoregulatory strategies (Aubret & Shine, 2010).

#### **2.2.2 Life histories and distribution**

In relation with the impact of climate change on the life-history of reptiles, there have been some changes in traits of species with limited dispersal ability such as *Lacerta vivipara*, which lives in the isolated mountain peaks of the southern Pyrenees (Chamaillé-Jammes et al.,

conditions these behaviors may cause the damage by a large number of elements such as those mentioned above. Amphibians exhibit maladaptive characteristics because the evolution takes time. Obviously, amphibians, and other organisms have defenses against the harmful factors. Exposure to sunlight over evolutionary time has undoubtedly resulted in mechanisms that help animals to withstand UV-B radiation (Cockel, 2001; Hoffer, 2000).

As we mention before the global modification of ecosystems has been induced the global warming and is identified as a significant and immediate threat that could radically affect the ability of species to survive. It is of great interest the ability of species to adjust to changes in the thermal environment, habitat structure and other fundamental niche axis. For terrestrial ectotherms, an increase in average temperature may affect their spatial distribution, physiological performance, reproductive biology and behavior (Dunham, 1993; Grant & Porter, 1992). As reptiles depend of external heat sources to regulate their body temperature climate is a key factor influencing the distribution and abundance of species

In contrast to the work conducted with amphibians, which has been extensive research on biological and ecological consequences of climate change, reptiles provide a scenario with broad potential. Although there are studies that suggest interesting perspectives on the issue, and then are exposed works concerning on the effects of ecological, physiological,

There are proposals that combine the spatial and temporal variation with the physiological (speed and strength) and morphological traits (shape of limbs) ecologically relevant. For example, in the *Urosaurus ornatus* lizard has been measured the speed and endurance of various populations, as well as the shape and size of their limbs through the altitudinal range where lizards are distributed. This lizard exhibit significant variation in the shape of his limbs corresponding to available perch types for each population, speed, and endurance. Thus the possible change in habitat structure and thermal regimes could result in an alteration of development patterns of lizards and cause changes in body shape and size of adults and in the way they use their habitat, behavior strategies, and physiological performance. Under this scenario only some population would be at risk, even though their evolutionary responses are consider slower compared with the speed of environmental change (Miles, 1994). On the other hand, long-term experimental studies with young *Notechis scutatus* snakes in enclosures with cold (19-22°C), intermediate (19-26°C), and hot (19-37°C) thermal gradients, suggested that these snakes compensated restricted thermal opportunities, although behavioral plasticity depending on thermal environment experienced to birth, therefore these conditions influenced subsequent thermoregulatory

In relation with the impact of climate change on the life-history of reptiles, there have been some changes in traits of species with limited dispersal ability such as *Lacerta vivipara*, which lives in the isolated mountain peaks of the southern Pyrenees (Chamaillé-Jammes et al.,

reproductive, behavioral and evolutionary change in reptiles.

**2.2.1 Physiological performance in reptiles and climate change** 

**2.2 Reptiles** 

(Pough, 2001; Zug, 1993).

strategies (Aubret & Shine, 2010).

**2.2.2 Life histories and distribution** 

2006). According to the author's records individual body size increases dramatically in four populations studied for 18 years. Body size increase in all age classes appears to be associated with an increase in temperature experienced by the offspring in their first month of life (August). The maximum daily temperature in this region during August raised 2.2 °C and lizard snout-vent length increased over 28%. As a result, body size of adult females increased dramatically, with the following increase of the litter size and the reproductive effort. One of the populations surveyed by a capture-recapture study suggested that adult survivorship was correlated with May temperature. All the fitness components investigated responded positively to increase in temperature, so it can be concluded *Lacerta vivipara* has obtained benefits of climate change. Instead, it is possible that climate change drastically alters the marshes, the main habitat for the *Lacerta vivipara*, due to temperature increase could cause more evaporation and reduces its moisture (IPCC, 2001), and the species may not be able to cope with changes in their habitat. (Chamaillé-Jammes et al., 2006). Araujo et al. (2006) also suggest that a continuous increase in temperature could cause a long-term contraction in suitable habitat for lizards and therefore increase the risk of local extinction.

#### **2.2.3 Thermoregulatory behavior and global warming**

Global warming and the potential reduction in areas with suitable characteristics for the distribution of the lizard *Heteronotia binoei* was calculated the climate component of their fundamental niche through physiological measurements (thermal requirements for egg development, thermal preferences, and thermal tolerances). The environmental data analyzed was high-resolution climate data from Australia (air temperature, cloud cover, wind speed, humidity, radiation, etc.), and biophysical models projecting over the Australian subcontinent to predict the effects of global warming. Estimates predict relatively little effect on the maintenance of metabolic costs, mainly due to the buffering effect of thermoregulatory behavior of lizards. The lizards could be able to regulate their body temperature (and their metabolic rates) moving between thermally suitable places at the surface (shuttling), as has been shown for the nocturnal ectotherms, and other diurnal lizards like *Psammodroums algirus* in the Mediterranean region of Spain (Diaz & Cabezas-Díaz, 2004; Kearney & Predavec, 2000). On the other hand, lizards also should evade high thermal environments hiding in shelters in the hottest hours of day (Kearney, 2002), and changing their daily and stationary activity periods (Bawuens et al., 1996), and their habitat selection (Stevenson, 1995).

#### **2.2.4 Effects of climate change on reproductive biology of reptiles**

Climate change is a threat to reptile populations due that in some lineages the temperature experienced by embryos during incubation determines the offspring sex ratio. Increases or decreases of temperature could turn to bias in the proportion of the clutch toward one sex. Nests exposed to an increase heat produced dramatic differences in sex ratios compared to those placed in shaded sites (Doody et al, 2004; Janzen & Morjan, 2001; St. Juliana et al., 2004). For this reason reptiles can useful as indicators of biological impact due global warming (Janzen & Paukstis, 1991; Mrosovky & Provancha, 1992). For example, related studies has been conducted in North America with the loggerhead turtle (*Caretta caretta*); results suggest that organisms could alter their nesting behavior as adaptive mechanism to the warming of historical nesting sites, that range from southeastern Florida to southeastern

Effects of Climate Change in Amphibians and Reptiles 173

of an abrupt increase in temperature that places the animals in the limit of their physiological tolerance, the peripheral populations of the tuatara would become extinct (Nelson et al., 2004). Finally some studies provide evidence that supports the proposal that the populations of reptiles compensate for differences in climate primarily through behavioral strategies (Doody et al., 2006; Gvozdika, 2002; Hertz & Huey, 1981). For example, in the Australian water dragon *Physignathus lesueurii* the maternal nesting behavior can respond for adjust the sex ratio and maintain viable populations across environmental extreme conditions, this compensate for climate differences by discriminating between potential nesting sites. This trait may be the most important to helping the species with

Global climate change has influenced many aspects of the biology and ecology of amphibians and reptiles, which in some cases was caused the decline of their populations or serious threats. However evidence suggest that the phenomenon itself does not directly affect the organisms, but acts in combination with biotic and abiotic factors increasing its effects, as we illustrated in the case of diseases and infections the drying aquatic habitats draying up, the invasion of competing species, and the diminishing of the immune system due thermal stress regarding to the reproductive biology of organisms suggests that climate change affects several aspects among the most visible traits: phenology, survivorship and fecundity. However, it remains unclear if global warming will alter population dynamics of all populations or some one would be balanced due areas with suitable conditions for distribution and survival of organisms, mainly in the case of amphibians, whose survival depends largely on the presence of moisture and healthy aquatic habitats. However, there are non or very few data and projections turtles and crocodiles, comparing with lizards, which has been suggested that around of 50% of the Mexican *Sceloporus* lizards would disappear for 2080, since if maximum environmental temperature continues rising constantly due a overcome of physiological threshold of tolerance and the reduction of their daily activity times, which would cause an energetic shortfall as a consequence of low food

Some potential adaptive responses already has bee suggested in different traits (behavior, physiology and morphology) among species affected by climate change. To test the likelihood of change in this traits due climate change requires the use of tools such as statistical analysis that incorporate phylogenetic hypotheses for the organisms under study, also an accurate estimate of the trait change rate both amphibians and reptiles is needed to understand the speed of the extraordinary rising of global environmental temperatures and

It is certain that climate global change will affect amphibians and reptiles around the world due synergic effects with other abiotic and biotic conditions. Our efforts should be concentrate in save as many populations and species we can, but first them all to understand the synergic effects and implement strategies to buffer them in regions when populations and species would be in the highest risk. It is quite possible that we cannot do anything against global warming and climate change, but we still can decide based on

thermal sex determination to compensate global warming (Janzen, 1992, 1994b).

**3. General conclusions** 

intake (Sinervo et al., 2010).

their effects in biodiversity.

scientific evidence what, when and how to do about it.

Virginia, where the sand temperature is lower and produces a higher proportion of males compared with those in Florida (Heppell et al., 2003). According to the IPCC (2001), Florida could experience a significant increase in temperature, so there is a high possibility of bias in the sex ratios, and a complete feminization of the setting of these the vast majority of the United Estates populations (Shoop & Kenney, 1992). The results indicates that an increase of 2° C is sufficient to cause feminization of clutches, and an increase of 3° C should drive to lethal incubation temperatures. As an alternative to temperature increase, turtles could potentially alter their nesting specific environment, looking for areas covered by vegetation, with greater proximity to the sea or groundwater. If turtles alter their oviposition season just a few days may be adapted to 1° C warming and if they did around a week, they could avoid the most extreme scenario (3° C); and this strategy could be the most viable adaptive mechanism for marine turtles in response to climate change (Hawkes et al., 2007).

In addition, evidence from genetic and behavioral analysis of the Painted Turtle populations *Chrysemis picta* in southeastern United States indicates that this turtle may disappear if do not develops traits that determine whether a balanced sex ratio, which directly affects their population dynamics (Girondot et al., 2004). Studies like those of Girondot et al., (2004) shows that species with temperature sex determination could be very sensitive to even modest variations (≤ 1 °C) in their local thermal environment. A slight increase in temperature could produce a high bias towards production of females (39° C). Such bias towards females results in a highly unequal sex ratio among adults and therefore if there are no males, females may lay eggs unfertilized eggs, and annual cohorts of offspring could lost and then the probability that the population becomes extinct.

The analysis of seasonal temperature variation and nesting behavior in *Chrysemis picta* suggest that pre-oviposition could mitigate climate change impacts on local populations located in less boreal latitudes and allow the production of males (Hays et al., 2001). Such nesting behavior modification may reduce the impact of local climatic variation, but may be insufficient for the populations living further north, since the young individuals may be low ability to survive the warm summer temperatures. It is believed that the metapopulation structure of these turtles among in the Mississippi River basin could help to mitigate the bias in sex ratio of the population caused by climate change if there is enough variation in both the thermal structure of suitable nesting areas, and migration rate between populations (Janzen, 1994).

In contrast, among the rhyncocephalians, lizards, and snakes with temperature sex determination, the threatened by global warming is higher in the tuatara (*Sphenodon punctatus*); a long generation time (which indicating limited potential to respond to rapid climate change), and extreme low temperature variation toward sex determination, with less than 1 °C drive the difference for the production of males or females (Nelson et al., 2004). Climate projections predict a significant increase among 1.4-5.8 °C in a very short period of time over the next 100 years (IPCC, 2001). Under this scenario reptiles may have four options to endure global warming: 1) modify its geographical range, 2) develop a genetic sex determination, 3) change their nesting behavior or 4) simply disappear (Janzen & Paukstis, 1991; Morjan, 2003). The tuatara may successfully manipulate the sex ratio of offspring by selecting the nesting site accord to vegetation, but apparently deeper nests in warm years to avoid bias toward males, which supports the proposition that the most viable strategy to deal with the effects of climate change is search sites with vegetal cover to nest. In the case of an abrupt increase in temperature that places the animals in the limit of their physiological tolerance, the peripheral populations of the tuatara would become extinct (Nelson et al., 2004). Finally some studies provide evidence that supports the proposal that the populations of reptiles compensate for differences in climate primarily through behavioral strategies (Doody et al., 2006; Gvozdika, 2002; Hertz & Huey, 1981). For example, in the Australian water dragon *Physignathus lesueurii* the maternal nesting behavior can respond for adjust the sex ratio and maintain viable populations across environmental extreme conditions, this compensate for climate differences by discriminating between potential nesting sites. This trait may be the most important to helping the species with thermal sex determination to compensate global warming (Janzen, 1992, 1994b).
