Literaturdatenbank
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Ibáñez Ricomá, A. (2014). Función de las señales múltiples en selección sexual y estrategias antidepredatorias en el galápago leproso, mauremys leprosa [function of multiple signals in sexual selection and antipredator strategies in the spanish terrapin, mauremys leprosa). Unpublished thesis , Universidad Complutense, Madrid.
Added by: Sarina Wunderlich (06 Jul 2014 16:11:41 UTC) |
| Resource type: Thesis/Dissertation BibTeX citation key: anon2014j View all bibliographic details  |
Categories: General Keywords: Caretta caretta, Cheloniidae, Habitat - habitat, Schildkröten - turtles + tortoises, Südwesteuropa - South-Western Europa, Testudinidae, Testudo graeca, Verhalten - ethology Creators: Ibáñez Ricomá Publisher: Universidad Complutense (Madrid) |
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| URLs http://digital.csi ... handle/10261/97768 |
| Abstract |
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Mauremys leprosa Conclusions 1. Spanish terrapins are able to communicate via chemical signals in water released by conspecifics. Females probably have a health condition-dependent chemical signal informing about their immunological response that affect responses of males. This would suggest that male turtles may base their mating preferences on chemical cues that honestly report the female’s health state and, thus, invest in the quality of their future offspring. Otherwise, chemicals of males may convey information about their size to females and other males. Probably, male M. leprosa of different sizes may differ in the chemical composition of their gland secretions, or in the amount of chemicals secreted. Female choice of pools occupied by larger males could protect them from the harassment and forced inseminations of other males. On the other hand, in males, chemical detection and avoidance of chemicals of larger and stronger males may prevent agonistic encounters with these males, in which smaller males could be at a disadvantage, allowing them to avoid injuries and save energy. In addition, male Spanish terrapins are able to distinguish between familiar and unfamiliar chemical cues found in the water. Similarly, male-male interactions in the Spanish terrapin could depend on the individual personality along the shy-bold axis and consequently affect their responses to conspecific chemicals. Bold males occupy pools with chemicals from familiar males unlike shy males that avoid familiar chemical cues. Nevertheless, both shy and bold males avoid to occupy pools containing odours of unfamiliar males. Taken together, these results suggest that male turtles might establish hierarchies during familiarization process, with bold males being dominant over shy ones. On the other hand, chemical cues from unfamiliar males might represent a hazard for both shy and bold males. Thus, boldness and body size could influence intrasexual competition between males. 2. Spanish terrapins show sexual dichromatism in limb but not in shell coloration. Males have less bright limb stripes than females suggesting that coloration is more important in sexual selection for females. Moreover, limb coloration of females seems to have higher variability than in males, and individual variation is related with size and health state, which suggests that female coloration may be implicated in mate choice. Sexual selection forces could act strongly on female limb coloration promoting honest signals that are reliable for their receivers. Alternatively, duller coloration of limb strips in males might be linked to melanic changes related with age or size. In addition, the small size together with the elevated mobility of male terrapins might carry on a higher predation risk and natural selection should favour less bright coloration. In contrast, shell coloration does not differ between sexes, although it is related with body size in males and females. Smaller turtles have smaller amount of UV reflectance in their shells, which could render small turtles more difficult to detect by bird predators suggesting that shell coloration might have a cryptic function. 3. Individuals of M. leprosa are able to assess the predation risk level in their environment and optimise their antipredator hiding response. Appearance times increase in concordance with the risk perceived by turtles, which behave more cautiously when perceived predation risk increases. However, waiting times decrease when risk increases, suggesting that turtles need more time to assess and monitor whether a predator is still present when the uncertainty of future risk is greater. The turtles show a size-dependent response, with longer appearance times for larger turtles when they are prone. For males, limb brightness is the main factor affecting their appearance times, but only in the “low” risk treatment. Nevertheless, appearance times when turtles are overturned are not affected by size, but males re-emerge from their shells relatively sooner than females. Waiting times are affected by size in the “medium” risk treatment, with smaller turtles starting to right later than larger ones. Taken together, these results suggest that males and females differ in terms of the traits that influence their boldness in risky contexts in different ways and that different aspects of the antipredator behaviour might be influenced by different factors. Similarly, conspicuousness to predator eyes (i.e. larger size and brighter colours) might lead to differences in appearance times in terrapins. Nevertheless, while the risk level increases, the turtles spend longer times inside their shells and need less time to initiate an active escape, and the relative contribution of size and coloration is less important (i.e. no relation in the “high” risk treatment). Thus, when risk increases, a turtle may assume that it has already been detected by the predator and then traits like body size or the degree of conspicuousness should not be important for their boldness in hiding behaviour, making the inter-individual differences in those traits irrelevant. 4. Hiding and exploratory behaviour are not related providing evidence that both traits are not a behavioural syndrome in female Spanish terrapins. The results obtained highlight that under risky situations, some components of boldness (i.e. appearance times) are affected by reproductive state of females. However, exploratory behaviour or waiting times do not differ between reproductive state classes. Gravid females appear relatively later from into their shells after a predatory attack than non-gravid ones. In addition, gravid females carrying a greater number of eggs tend, although not significantly, to have longer appearance times as well as longer waiting times under “low” risk but shorter waiting times under “high” risk. Those results may suggest that larger clutches could affect boldness in risky contexts of Spanish terrapin females. The lack of differences in relative and absolute weight between gravid and non-gravid females suggest that differences in appearance times might be due to metabolic-physiological costs and a worse condition of gravid females associated with egg production and embryo maintenance. However, gravid females might act more cautiously to protect their immediate higher fitness with respect to non-gravid ones. 5. Basking activity was related with health state (i.e. total number of leukocytes and haematocrit) and limb coloration. Male turtles that spent less time basking had higher total WBC counts and higher haematocrit values. Thus, males with higher basking activity could have less oxygen requirements due to their lower mobility and consequently reduced metabolical expenditure. Similarly, males that spent more time basking could be more susceptible to infection due to the fact that they dedicate less time to foraging which may compromise their immune system. Otherwise, basking behaviour could carry associate costs in terms of predation risk with more conspicuous individuals reducing their basking activity to avoid be easily detected by potential predators. Further studies should include females to clarify the role of coloration showiness in basking patterns in freshwater turtles.
Added by: Sarina Wunderlich |