Anura: Craugastoridae: Pristimantis) in the Eastern Andes of Colombia
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Title: Influence of environment on thermal ecology of direct-developing frogs (Anura: Craugastoridae: Pristimantis) in the eastern Andes of Colombia. Edgar A. Bernal Castro 1*, Erika Ximena Cruz Rodríguez 2, José Nicolás Urbina3 Cardona; Andrew J. Crawford 1 1 Department of Biological Sciences, Universidad de los Andes, Bogotá, 111711, Colombia. 2. Department of Biology, Universidad del Tolima, A.A. 546, Ibagué, Colombia. 3. Department of Ecology and Territory, Pontificia Universidad Javeriana, A.A. 56710, Bogotá, Colombia. * Communicating autor Physical address: Colombia, Departamento del Huila, Ciudad Neiva, Calle 6c # 16 – 03, Barrio Calixto. Email: [email protected]; Alternative email: [email protected] Celular: 57 - 3158507780 Keywords: Physiology, Environmental, Amphibians, Altitudinal, Coverage. Abstract Amphibian’s temperature is a critical variable in the biology and ecology of organisms, especially ectotherms whose body temperatures depend on environmental conditions. In this study we compared the thermal biology of 13 species of frogs of the genus Pristimantis across 11 sites across different elevations in the Eastern Andes of Colombia, and sought to correlate ecophysiological variation with environmental variation at two scales. We measured critical thermal maximum (CTMax) and critical thermal minimum (CTMin) temperatures of reach frog, along with air temperature, and microhabitat temperature and structure. As the height of the locality increases, CTMin decreases in greater scale in relation to the CTMax, which is high in relation to the maximum temperature reported for highlands. There are also differences in thermal physiology between the flanks of the mountain range. The variables of herbaceous cover, litter cover and Humidity are related to the thermal limits of the 1 species. The changes in thermal physiology include a dynamic that involves not only altitudinal and latitudinal changes, but also the structure and composition of the microhabitats that each species inhabits, as well as the evolutionary history of the species, which can contribute to the conservation of characters such as the CTMax in highland species, which, in turn, raises new questions regarding the survival of species in the face of climate change phenomena. Introduction Global climate change is expect to affect all terrestrial regions of the world (Burck et al. 2018; Hansen et al. 2018; Soediono 1989). Current and future changes in ecosystems require a greater understanding of how species survive and adapt to changing environmental conditions (Corn 2005; Gilbert and Miles 2017; Gomez et al. 2016; Sinervo et al. 2010). Temperature is an essential environmental variable that largely determines biological processes such as growth, survival, and reproduction (Angilletta 2009) Temperature also plays a fundamental role in determining species abundance and range limits (Andrewartha and Birch 1954; Janzen 1967). In poikilotherms, body temperature is associated strongly with environmental temperatures (Angilletta et al. 2002; Navas 1997, 1999) This explains the presence of species and their distributions in altitudinal gradients also associated with other intrinsic and extrinsic variables of organisms such as physiology and ecology. (Bernal and Lynch 2008; Ghalambor et al. 2006; Janzen 1967; Meza-Joya and Torres 2016). By studying the ecophysiological variation in closely related frogs across elevations and between flanks we hope to elucidate the role of local environmental variation in driving Organisms can respond to changes in temperature in four ways: adapt, acclimate, migrate to better conditions, or become extirpated (Sinervo et al. 2010). Adaptation can be revealed by comparing heritable traits in populations of the same species found in different environments, particularly thermal physiological traits (Moritz et al. 2000; Savolainen, Lascoux, and Merilä 2013; 2 Wiens and Graham 2005). Some differences between populations, however, may reflect acclimatization or phenotypic plasticity, defined as the ability individual organisms to alter morphological or physiological trait values in response to local environmental conditions (Piersma and Drent 2003; Pigliucci 2006; Scheiner 1993). Whether by acclimation (within generations) or adaptation (between generations), organisms change their physiological characters response to different climates (Navas 1999), since temperature affects processes such as locomotor performance at lower or higher temperatures, which in turn affects the fitness (Gvoždík, Castilla, and Gvozdik 2001; Martin and Huey 2008; Navas 1999; Navas, Gomes, and Carvalho 2008). In this way, the vulnerability of organisms to changes in environmental temperature is conditioned by the speed of response to physiological changes (Miles 1994). For example, acclimation can generate a rapid physiological response to a change in temperature, but an ancestral character (adaptation) of high physiological tolerance to abrupt temperature change can also be useful in an ecological context. All organisms have certain physiological tolerances, beyond which performance drops to dangerous levels. In thermal biology, the upper and lower bounds are referred to, respectively, as the Critical Thermal Maximum (CTMax) (Lutterschmidt and Hutchison 1997) and Critical Thermal Minimum (CTMin) (Jaco Klok and Chown 1997). CTMax and TCMin are the thermal point at which locomotor abilities suffer notably, at which point the animal would presumably be unable to escape predators, capture prey (in the case of predators), and would lead to death (Cowles and Bogert 1944). Physical limits can be modified at the population or species level depending on the location and height (Angilletta et al., 2002, Carlos Arturo Navas, 1999). Species with wide thermal ranges are more likely to survive as they can tolerate changing climates through the generations. These subjects are studied mainly at the species level, but little is known about whether the thermal dynamics are shared between populations in different altitudinal ranges and how populations of the same species differ in different localities. 3 Physiothermal limits can change or be conserved according to the evolutionary history of the species, the habitat and the altitude (strongly associated with environmental temperature) also influence the physiological dynamics of the species allowing to expand or reduce the thresholds of thermal tolerance (Angilletta et al. 2002; Navas 1999). Species with wide thermal ranges are more likely to survive as through generations can tolerate climates changing. In general terms, the CTMax is strongly conserved among groups of poikilotherms while the CTmin is much more variable (Araújo et al. 2013). In amphibians, physiology has a stronger relationship with thermal ecology than phylogenetic affinities (Navas, Gomes, and Carvalho 2008). The relationship between physiology and the environment has allowed some amphibian groups to colonize different environments (Angilletta et al. 2002; Navas et al. 2013) adapting to the generations its physiology to surrounding environmental changes. However, not all physiological characters are under the same selection pressures. In general, TCmax appear to be mostly conserved in several species of ectotherms (Angilletta Jr., 2009, Gomez et al., 2016), and TCmin may have higher rates of change in altitudinal gradients (von May et al., 2017). But in specific terms, physiological changes in groups with closely related species whose habitat is found in complex geographical areas such as mountain ranges are poorly understood. The habitat is a set of features area in which interact resources and environmental factors that create suitable conditions for the establishment of a population (Hall, Krausman, and Morrison 1997; Morrison, Marcot, and Mannan 1998). Within the thermal ecology, habitat and temperature are related by configuring the structure of communities (Simon et al., 2015), and determine the thermal behavior of ectotherms against environmental variations (Carlos Arturo Navas, 1999). The habitat is a set of characteristics of an area in which resources and environmental factors interact, generating suitable conditions for the establishment of a population (Hall, Krausman, & Morrison, 1997; Morrison, Marcot, & Mannan, 1998), Within the Habitat There are small areas called microhabitat which refer to the exact substrate where individuals develop a certain metabolic function, which is a function of the range of an individual's home and the way he uses the resources (Hall et al., 1997). Although the definition of 4 microhabitat is varied among the authors, the immediate surrounding area (+/- 1m) is also included as a microhabitat at the point where the individuals are at a given moment (Cook & Jennings, 2007) Both habitat and microhabitat are composed by different environmental variables (temperature, humidity, etc.) and structural variables (plant strata, litter). Within the thermal ecology, habitat and temperature are related by configuring the structure of communities (Simon et al., 2015), and determine the thermal behavior of ectotherms against environmental variations (Carlos Arturo Navas, 1999). Microhabitat is known to the exact substrate where individuals develop specific metabolic function, (Hall et al., 1997). Although the definition of microhabitat varies among authors, the immediate surrounding area (+/- 1m) is also included as a microhabitat at the point where the individuals are at a given moment (Cook & Jennings, 2007) The habitats