查看更多>>摘要：Abstract Color and pattern are often dynamic traits that change throughout an individual's lifetime. Still, long‐term shifts in coloration have received limited attention. Dendrobatid poison frogs are a classical system in the study of color and pattern evolution in which both sexual selection and predation avoidance are thought to drive the evolution of color and pattern at the population and species level. Here, we highlight an overlooked axis of pattern diversity, within individual variation, using three species in the genus Dendrobates. We collected longitudinal photographs of individuals at the National Aquarium to test the hypothesis that patterns shift predictably throughout the lifetimes of individual frogs. In all three species, we found a consistent reduction in the relative area of aposematic color as individuals aged and that the rate of pattern shift did not differ between the sexes. Consequently, within individual variation in coloration may confound inferences from ecological studies that inherently assume individual pattern is static. Finally, we note that using simple and noninvasive photography protocols, animals in zoos and aquaria have the potential to deepen our understanding of how color and pattern change throughout the lifetimes of a wide range of species.
Solène MarionUr?ka Dem?arAlthea L. DaviesPhilip A. Stephens...
13页
查看更多>>摘要：Abstract With increasing levels of outdoor recreation activities, consequences for wildlife through interactions with recreationists are highly variable. Behavioural changes in wildlife are one potential consequence of interactions with outdoor recreationists. In ungulate populations, vigilance and flight responses are well‐known antipredator behaviours, and an increase in their level indicates a more intense stress level which, ultimately, can have consequences for animal fitness. In Scotland, the geographical distribution of red deer (Cervus elaphus) overlaps greatly with areas used for popular outdoor activities such as hill walking. In this piece of research, we studied red deer time allocation, vigilance, and flight behaviours near a popular hiking path using camera traps. We positioned the cameras in transects at different distances (25, 75, and 150?m) from the path and recorded hiking activity using an automated people counter. Red deer behaviour was categorized from photo analysis as (1) no response (e.g. feeding and resting), (2) vigilant (i.e. upright head position), and (3) flight response. We also investigated demographic variables (group size and sex) and the direction of red deer movement relative to the trail. We used generalised linear mixed models to analyse behaviour in relation to the distance from the hiking track, hiking activity, time of the day, demographic, and environmental variables. We did not find an increase in vigilance or flight behaviour in relation to the distance from the hiking path or the hiking activity. These results suggest that red deer, in our study area, are habituated to the presence of hikers and may spatially avoid areas close to the hiking path instead of displaying cost‐intensive behaviour (i.e. flight or vigilance behaviour).
S. GrignolioF. BrivioR. ChirichellaM. Apollonio...
8页
查看更多>>摘要：Abstract Animal weapons are one of the most studied morphological traits, particularly in Artiodactyla. Since in polygynous species males with larger weapons tend to be more successful in gaining access to females, researchers have traditionally focused on horn size. However, in species with limited horn size, weapon size has been assumed to have a reduced or null effect on life history traits. We examined the effect of intrinsic and extrinsic factors on the length of the second and third segments of Alpine chamois horns (Rupicapra rupicapra) in a population living in a poor environment. Our aim was to test how environmental conditions affected weapon growth and whether compensatory growth occurred. We showed that horn length was isometric to body size, although male horns grew more quickly. Ecological factors such as snow and forage availability affected weapon length, though mildly. No sign of compensatory growth was detected. We inferred that chamois mainly use horns as armament in intrasexual interactions. However, horn length was not a key element since horn growth remained isometric, at least under suboptimal ecological conditions. In species without extreme weapons, the handicap caused by longer horns is likely not compensated by an increase in individual fitness.
查看更多>>摘要：Abstract The division of labor into sterile and reproductive castes in social insects is often reflected in marked morphological differences, which might have played an important role in the remarkable adaptive success of these organisms. Some ant lineages have undergone further morphological differentiation, with the evolution of differences within the worker caste. In this study, we characterize morphological diversity in the head of Pheidole ants by comparing differences in size and shape among species and between minor and major worker subcastes. To this end, we integrate data from high‐resolution images, geometric morphometrics, and phylogenetic comparative methods. Our results indicated differences in morphological variation of each subcaste with respect to their geographical distribution, with distinct morphological patterns and evolutionary routes related to head shape. Allometry was shown to be a crucial element for the differentiation within and between each subcaste, corroborating the role of size in their morphological evolution. Additionally, we observed that closely related species often diverge considerably in morphospace, whereas convergence in their morphospace occupation characterizes some West and East Hemisphere species. Finally, although multiple shifts in the rate of morphological evolution occurred during the Miocene, the timing and position of these shifts were independent of size and shape, suggesting that their evolution has been decoupled throughout Pheidole evolution.
M. A. Domínguez‐GodoyR. HudsonB. MontoyaE. Bastiaans...
11页
查看更多>>摘要：Abstract Aggressive behavior is performed in the context of intraspecific competition for gaining access to mates, food, or suitable territories. However, aggressive confrontations may divert time and energy from other important activities and increase the likelihood of suffering physical injury or predation. Aggressive behavior is particularly costly for ectotherms because it may reduce the time available for thermoregulation, which is a time‐consuming activity but indispensable for adequate maintenance of metabolic processes. In this study, we analyzed the long‐term effect of the thermal quality (i.e. the degree of discrepancy between the temperatures available in a given environment and temperatures that animals prefer) on the aggressive behavior of the mesquite lizard Sceloporus grammicus. Our hypothesis was that time allocated to aggressive behavior in low thermal quality environments is diverted from time spent on the acquisition and maintenance of an adequate body temperature. Accordingly, we found that lizards from the low thermal quality location (i.e. low environmental temperature) exhibited less aggressive behavior than those captured in middle and high thermal quality locations. Our results show that in the low thermal quality location aggressive behavior was almost absent, suggesting that this behavior may interfere with the acquisition and maintenance of an adequate body temperature. Therefore, it is likely that the benefits of thermoregulation outweigh those of aggressive behavior at low thermal quality locations.
查看更多>>摘要：Abstract Human activities are altering natural ecosystems, leading to widespread environmental change that can vary across spatiotemporal scales, thus creating dynamic, novel conditions at both large and small scales. In highly disturbed aquatic systems, elevated turbidity is one common stressor that alters the sensory environment of fishes and can disrupt communication, including mate choice, driving population‐level shifts in visual communication traits such as nuptial coloration. At a smaller, within‐population scale, we can expect similar adaptive divergence to a heterogeneous visual landscape. Using the cichlid fish, Pseudocrenilabrus multicolor, we investigated within‐population variation in diet and nuptial coloration by sampling fish from microhabitats within a relatively small site (~0.14?km2). These visual microhabitats are affected by different types of human disturbance at a very small scale leading to significant differences in water clarity (i.e. turbidity). We used three, non‐mutually exclusive working hypotheses to test if (1) males in low turbidity invest more in carotenoid‐based coloration (economy of pigments hypothesis), (2) fish from low‐turbidity sites eat more carotenoid‐rich foods (diet hypothesis), and (3) fish are habitat matching. Stomach content analyses revealed relatively high overlap in diet across microhabitats; however, fish from stations with the lowest turbidity consumed relatively more plant material (high in carotenoid content) than fish captured at high‐turbidity stations. Males from clearer waters displayed significantly more carotenoid‐based, red and yellow coloration than fish found in microhabitats with higher turbidity, similar to between‐population color variation in this species. Furthermore, larger fish displayed more carotenoid coloration overall, but there was no difference in mean male size among microhabitats suggesting that fish were not sorting into microhabitats. Our results suggest that within‐population variation in nuptial coloration could be associated with microhabitat heterogeneity in the visual landscape driven by turbidity, a diet with more carotenoid‐rich prey items, or a combination of both.
NSTL
Wiley