The Ecological Significance of Sexual Dimorphism in Size in the Lizard Anolis conspersus.
27 Jan 1967-Science (American Association for the Advancement of Science)-Vol. 155, Iss: 3761, pp 474-477
TL;DR: Anolis conspersus selects prey from a wide range of taxa and shows no obvious intraspecific specialization not connected to differences in microhabitat and prey size.
Abstract: Adult males of Anolis conspersus capture prey of significantly larger size and occupy perches of significantly greater diameter and height than do adult females; similarly, these three dimensions of the niche are significantly larger for adult females than for juveniles. Adult males on the average eat a smaller number of prey, and the range in size of prey is larger. The relationship between the average length of the prey and that of the predator is linear when the predator size is above 36 millimeters, but becomes asymptotic when it is below that value. Subadult males as long as adult females eat significantly larger food than do the latter, but only in the larger lizards is this correlated with a relatively larger head. Anolis conspersus selects prey from a wide range of taxa and shows no obvious intraspecific specialization not connected to differences in microhabitat and prey size. The efficiency of this system for solitary species is pointed out.
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TL;DR: It is suggested that the immediate responses of individual consumers to resource pulse events can provide insight into the mechanisms by which these consumers ultimately influence community‐level processes.
Abstract: Resource pulses are brief periods of unusually high resource abundance. While population and community responses to resource pulses have been relatively well studied, how individual consumers respond to resource pulses has received less attention. Local consumers are often the first to respond to a resource pulse, and the form and timing of individual responses may influence how the effects of the pulse are transmitted throughout the community. Previous studies in Bahamian food webs have shown that detritivores associated with pulses of seaweed wrack provide an alternative prey source for lizards. When seaweed is abundant, lizards (Anolis sagrei) shift to consuming more marine-derived prey and increase in density, which has important consequences for other components of the food web. We hypothesized that the diet shift requires individuals to alter their habitat use and foraging activity and that such responses may happen very rapidly. In this study, we used recorded video observations to investigate the immediate responses of lizards to an experimental seaweed pulse. We added seaweed to five treatment plots for comparison with five control plots. Immediately after seaweed addition, lizards decreased average perch height and increased movement rate, but these effects persisted for only 2 days. To explore the short-term nature of the response, we used our field data to parametrize heuristic Markov chain models of perch height as a function of foraging state. These models suggest a "Synchronized-satiation Hypothesis," whereby lizards respond synchronously and feed quickly to satiation in the presence of a subsidy (causing an initial decrease in average perch height) and then return to the relative safety of higher perches. We suggest that the immediate responses of individual consumers to resource pulse events can provide insight into the mechanisms by which these consumers ultimately influence community-level processes.
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Additional excerpts
...For example, perch height varies depending on sex (Lister & Garcia Aguayo, 1992; Schoener, 1967, 1968), predation risk (Scott, Wilson, Jones, & Andrews, 1976), abiotic conditions (Lopez- Darias, Schoener, Spiller, & Losos, 2012), and hunger level (Paterson, 1999; Stamps, 1977; Stamps & Tanaka,…...
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TL;DR: In this paper, the authors studied two populations of Sceloporus ochoteranae to determine if there were differences in body size, sexual dimorphism, and clutch size.
Abstract: We studied 2 populations of Sceloporus ochoteranae to determine if there were differences in body size, sexual dimorphism, and clutch size. Males were larger and had larger heads than females. Sceloporus ochoteranae from the Canon del Zopilote (elevation 600 m) were smaller, had narrower heads and longer femurs, and had smaller clutches than those from Acatlan (elevation 1,250 m).
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TL;DR: In this paper, a model based on cost and gain functions is developed for predicting the relative magnitude of the Malthusian parameter, m, for different phenotypes of grazing small rodents.
Abstract: A graphic model based on cost and gain functions is developed for predicting the relative magnitude of the Malthusian parameter, m, for different phenotypes. The analysis is mainly restricted to grazing small rodents. The cost function is derived by depicting the probability of death due to predation, parasitism etc. as a function of time spent outside the nest. The gain function is derived by comparing the energy obtained by digestion, with energy used (or needed) for maintenance metabolism, both when outside and inside the nest. The model is applied for predicting the relative magnitude of the Malthusian parameter of small versus large phenotypes of grazing rodents. Of these, the smaller phenotypes are concluded to have the larger Malthusian parameter. This may not hold true for hunters (granivores and predators). These conclusions are used for reinterpreting the often observed geographical size trend in warm-blooded vertebrates (Bergmann's rule). The model is further applied to the determination of the relative magnitude of the Malthusian parameter for aggresive and docile strategies hypothesized in Chitty's theory for fluctuating populations. Of these, the aggressive strategy is concluded to have the lowest Malthusian parameter. Although not verifying Chitty's theory, these results support the earlier hypothesis that the aggressive strategy may under certain situations have lower survival. Based on the present model, nothing can be said about whether or not a polymorphic population as hypothesized by Chitty will exhibit oscillations.
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TL;DR: The eight species of the genus Anolis in Puerto Rico can be divided into four morphological similarities as discussed by the authors : perch height, perch diameter, high-shade preference and low-shading preference.
Abstract: The eight species of lizards of the genus Anolis in Puerto Rico can be divided into four morphological similarities. One, Anolis curvieri, is very different from the rest and has not been discussed here. The other seven species fall into three groups. Each of these groups occupies a different structural habitat which can be defined in terms of perch height and perch diameter. Within each of these three groups the species have very similar but not indential structural habitats but differ very widely in climatic habitat defined in terms of shade. Shade preferences seem to result from the temperature preferences of the species involved. In each group there is one species with high shade preference which is essentially restricted to the mountains. Each group also has a species with a lower shade preference which occurs in the lowlands and extends up into the mountains in exposed or sunny situations. One of the three groups has an additional species which is restricted to the hot and southwest corner of Puerto Rico. When one compares the temperature preferences or eccritic temperatures of the various species, one finds in each group that the highland species has a lower eccritic temperature than does the lowland species. There is little temperature difference between the lowland species and arid southwest species in the group where this additional third species is present. The species within each structural habitat show many morphological similarities which may be the result of their being closely related or may be the result of adaptation to similar environments. The differences in microhabitat between the Puerto Rican anoles separate them spatially though not completely. In species occupying different structural habitats in the same area the overlap may involve part of the home range of most of the individuals in the area. In species occupying the same structural but different climatic habitats the overlap may involve all of the home range of some individuals but of only a small fraction of the individuals in the total population. The spatial separation among Puerto Rican Anolis can be suggested to be of ecological significance because it reduces interspecific competition and because it allows the various species to adapt more precisely to different parts of the available habitat. Thus members of a genus may exploit the habitat more efficiently.
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01 Jan 1964
TL;DR: The life of the rainbow lizard , The life of a rainbow lizard, مرکز فناوری اطلاعات £1,000,000 ($2,000; £1,500,000)
Abstract: The life of the rainbow lizard , The life of the rainbow lizard , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی
119 citations
"The Ecological Significance of Sexu..." refers background in this paper
...On the basis of essentially the same pattern of staining, other investigators have reached the same conclusion (3, 4), or have attributed staining additionally or alternatively to the processes of the bipolar cells (5, 6), the ganglion cells (4, 5), or centrifugal fibers from the optic nerve (7)....
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...A greater proportion of large insects were found in larger adult males than in adult females of Anolis lineatopus and Agama agama (4, 5); similarly, juveniles take smaller food than adults (5-7)....
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