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Adaptive strategies in amphibians living under environmental stress
|Other Titles:||Strategii adaptative ale amfibienilor care traiesc în conditii de stres ambiental|
|Abstract:||[EN] Amphibians are ectothermic organisms, characterised by complex life cycles that involve the occurrence of some major changes (e.g. morphological, physiological, behavioural changes) throughout their ontogenetic development, usually associated to habitat type transitions (e.g. from aquatic to terrestrial) (Wilbur 1980). Ontogenetic development in amphibians is constrained by environmental humidity, given the high permeability of the egg protective layers (Duellman & Trueb 1994).
Amphibians are suffering a severe worldwide decline, being among the most affected vertebrates with nearly one-third (32.5%) of the species threatened (Houlahan et al. 2000; Stuart et al. 2004; Lannoo 2005; McCallum 2007; Collins & Crump 2009; Baillie et al. 2010). The causes of this phenomenon are complex and yet poorly understood, while the responsible environmental stressors are multiple, interact among them, and often act synergistically (Young et al. 2001); furthermore, their impact may vary regionally, both within and between species (Blaustein & Kiesecker 2002; Gascon et al. 2007; Sodhi et al. 2008; Blaustein et al. 2012). The major responsible factors documented are habitat fragmentation and destruction, climate change, UV-B radiation level increase, chemical pollution, pathogens, alien species, over-exploitation (e.g. Young et al. 2001; Baillie et al. 2010; Vitt & Caldwell 2014). Acting individually or together, environmental stressors may induce a series of direct or indirect changes upon amphibians’ phenology, behaviour, physiology, metabolism (also affecting their body condition), and depending on their severity, may cause population declines (e.g. Sodhi et al. 2008; Hoffmann & Sgrò 2011; Blaustein et al. 2012).
As organisms with indeterminate growth, amphibians may adopt a diversity of strategies (or trade-offs) in resource allocation between growth and reproduction to maximize reproductive success and survival, in response to a given environment (e.g. Heino & Kaitala 1999; Fox et al. 2001; Cogălniceanu & Miaud 2003; Morrison & Hero 2003; Iturra-Cid et al. 2010; Hjernquist et al. 2012; Cogălniceanu et al. 2013). I used various approaches and methods and focused my studies upon life history trade-offs in amphibians within the context of global environmental changes. Therefore, I proposed a set of objectives that allowed me to characterize a broad range of life history strategies in the studied populations, throughout different stages of their life cycle|
MATERIAL AND METHODS The studied amphibians are representatives of three anuran families: Pelobatidae (Pelobates fuscus and P. syriacus), Bufonidae (Bufo bufo and Rhinella schneideri) and Microhylidae (Dermatonotus muelleri), and one urodelan family: Salamandridae (Lissotriton vulgaris).
GENERAL GUIDELINES (faunistical data) original data and information should be easily and clearly delineated from those already published; where possible, the associated metadata regarding habitat, environmental conditions at the moment of the study, life stage of the observed individuals, number of individuals, etc., should be exhaustively provided; It is highly desirable to provide supplementary information, such as killed animals (e.g. road kills, intentional killing, vandalism, predatorism/cannibalism), the presence Doctoral thesis summary Adaptive strategies in amphibians living under environmental stress Florina STĂNESCU 24 of predatory species, syntopic species, human impact, collected specimens (if applicable) – the name of the institution and the collection where the specimens were deposited and specimen code, photographs, video/audio recordings. Raw distribution data and associated metadata should be made available online, as annexes in an accessible format (Wieczorek et al. 2012; Costello & Wieczorek 2014).
SPECIFIC GUIDELINES (occurrence data) occurrence site should be indicated by precise geographic coordinates; it is recommended to provide information regarding the instrument used to determine the geographic coordinates of the occurrence site, the brand and type (e.g. GPS, Google Earth, Google Maps, etc.); where, for various reasons, the author does not want to provide the exact site of occurrence using geographic coordinates (e.g. to protect a study population), it is recommended to use UTM grids (e.g. 5×5 km) indicating: the geographic coordinates of the corresponding UTM cell centroid, the code of the UTM cell, the source for the UTM grid (e.g. Lehrer & Lehrer 1990), the name of the nearest locality and the corresponding county/district; in such cases it is also recommended to provide the altitude of the exact occurrence site, and not the altitude of the UTM cell centroid; for transects up to 500 m within a narrow altitudinal range, the author may provide the geographic coordinates corresponding to the centroid of the transect; it is recommended to provide the geographic coordinates in a consistent format; WGS 1984 datum with decimal degrees is preferred, as it is the most commonly used by GPS units around the globe; altitude should be provided for the exact occurrence site; it is desirable to provide supplementary information regarding the occurrence site: locality, county, toponymy (where applicable), and avoid using exclusively local toponymy, which are difficult to locate for instance, by non-native researchers; occurrence date should be accurately provided (e.g. dd-mm-yyyy); it is recommended to provide occurrence data for each species (where applicable), in a centralized format, most desirable as a table, at least for the essential data such as occurrence site, altitude, date.
|Description:||Contiene resumen en inglés y en rumano|
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