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: Bite force performance measures can be used as ‘traits’, and thus be used in integrative studies at multiple levels of organismal biology, and will help the understanding of the functions, capacities, and evolution of jaw–cranial musculoskeletal systems.
Abstract: Measurements of whole-organism performance traits have been useful in studies of adaptation and phenotype– environment correlations. Bite force capacities may be tightly linked to both the type and magnitude of the ecological challenges of food acquisition, mate acquisition, and antipredation in vertebrates. In the present study, we present technical details on bite meters and on measuring bite forces. The ability to take reliable measurements depends on specific features of the measuring device and on where in the mouth the bite is applied. Using both previously available and original data, we demonstrate several ecologically and evolutionarily relevant features of bite force measurements. First, maximal bite forces are repeatable among individuals across all vertebrates studied to date. Second, in ectotherms such as lizards, maximal bite forces are affected by body temperature and motivational states. Third, bite forces are strongly correlated with head size and shape. Fourth, bite forces correlate with features of prey of vertebrates. Finally, bite forces are linked to male dominance and correlated with social-display structures. Thus, bite force performance measures can be used as ‘traits’, and thus be used in integrative studies at multiple levels of organismal biology. Accordingly, bite force data will help our understanding of the functions, capacities, and evolution of jaw–cranial musculoskeletal systems. Moreover, a plethora of opportunities exist for the use of bite force measurements, and if methods are carefully applied, several levels of organismal and ecological organization can be integrated to aid our understanding of the ecology and evolution of vertebrate taxa. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 93, 709–720.
191 citations
Cites background from "The Ecological Significance of Sexu..."
...For many species, maximal bite force may be an infrequently used, but exceedingly important factor in the outcome of agonistic and mating encounters (Schoener, 1966; Cooper & Vitt, 1993; Lailvaux et al., 2004; Huyghe et al., 2005), resource use (Hernandez & Motta, 1997; Herrel et al., 1999b; Herrel et al., 2001a, Herrel, De Grauw & Lemos-Espinal, 2001b; Grubich, 2003), and breadth of the resource niche (Herrel, Van Damme & DeVree, 1996; Herrel et al., 1999a)....
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...© 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 93, 709–720 Schoener TW. 1966....
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TL;DR: Patterns of convergent and divergent evolution of Caribbean Anolis lizards suggest that the habitat specialist niches into which these anoles have evolved are multidimensional, involving several distinct and independent aspects of morphology.
Abstract: Convergent evolution has played an important role in the development of the ecological niche concept. We investigated patterns of convergent and divergent evolution of Caribbean Anolis lizards. These lizards diversified independently on each of the islands of the Greater Antilles, producing the same set of habitat specialists on each island. Using a phylogenetic comparative framework, we examined patterns of morphological convergence in five functionally distinct sets of morphological characters: body size, body shape, head shape, lamella number, and sexual size dimorphism. We find evidence for convergence among members of the habitat specialist types for each of these five datasets. Furthermore, the patterns of convergence differ among at least four of the five datasets; habitat specialists that are similar for one set of characters are often greatly different for another. This suggests that the habitat specialist niches into which these anoles have evolved are multidimensional, involving several distinct and independent aspects of morphology.
186 citations
Cites background from "The Ecological Significance of Sexu..."
...The best studied of these relationships is the positive correlation between body size and prey size (Schoener 1967, 1970)....
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...…territorial species may have larger heads to enhance fighting ability [Stamps 1977; Herrel et al. 1996]); and sexual size dimorphism, which may relate to extent of territoriality, intrasexual resource partitioning, or sex-specific adaptation (Schoener 1967; Butler et al. 2000; Losos et al. 2003a)....
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TL;DR: Differences in head length and snout-vent length were computed for all combinations of Anolis species taken two at a time on the Greater Antilles to study the tendency to converge and diverge associated with structural-habitat similarity and spatial overlap.
Abstract: Differences in head length and snout-vent length were computed for all combinations of Anolis species taken two at a time on the Greater Antilles. There is a tendency to converge associated with structural-habitat similarity: Males of species whose range projections on a map do not overlap are significantly closer in size if structural habitats are similar than if different. There is a tendency to diverge associated with spatial overlap: Species with substantial structural habitat similarity are more different in head and snout-vent length if their ranges overlap than if allopatric. When a given species overlaps in part of its range with a second smaller species of similar structural habitat, convergence in head and snout-vent length is about as frequent as divergence; that is, the given species is as likely to increase its size as to decrease that size. Relatively large species converge significantly more often in this situation than do smaller species. However, where a given species overlaps in part of ...
186 citations
TL;DR: Two features of the habitat, the variation of moisture patterns in space and the fluctuation of resources in time, appear to be correlated with most of the differences in the means and standard deviations of these distributions.
Abstract: The tendency for the lengths of adult insects of sweep samples from forest understories, considered both as species and as individuals, to fit a two-parameter lognormal distribution rather than a simple normal distribution, and a three-parameter lognormal distribution best of all, is documented for some tropical and temperate areas. Two features of the habitat, the variation of moisture patterns in space and the fluctuation of resources in time, appear to be correlated with most of the differences in the means and standard deviations of these distributions. In general, samples from drier areas or those with longer growing seasons have larger species, and samples from areas with the more uniform moisture conditions and growing seasons have the smaller standard deviations of their species' lengths.
184 citations
TL;DR: Evidence for intersexual food (prey size) partitioning was weaker than expected from the widespread dimorphism in body size or relative head size found among lacertid lizards, and the development of "body segments" was in some instances inconsistent with the competitive hypothesis, the largest sex having relatively smaller trophic structures.
Abstract: Lacertid lizards exhibit sexual dimorphism in size corrected values for abdomen (always larger in females) and head (larger in males) lengths. Relative abdomen length increased with SVL in females but did not in males. The mean abdomen/head ratio for juvenile lizards (sexes pooled) was lower than that of females but did not differ from that of males in any of the studied species. Therefore, the ontogenetic development of the main body segments (abdomen and head) was isometric in male lizards, whereas female abdomen exhibited positive allometric growth. Standardized independent contrasts (Felsenstein's method) of female abdomen to head ratio and of the slope of the regression of clutch size on SVL explained a significant amount of variation in sexual size dimorphism in a stepwise multiple regression model. The fact that sexual size dimorphism was best explained by variables related to female reproductive investment, together with the ontogenetic trajectories of body segments suggest that sexual size dimorphism results mainly from variation in female size. Despite the suggested prominent role of selection on female body size in determining the outcome of size dimorphism, there was also evidence of selection for increased body size in males, which were the largest sex in species with low selective pressure towards increased female size (constant clutch size or low fecundity slope over size). Evidence for intersexual food (prey size) partitioning was weaker than expected from the widespread dimorphism in body size or relative head size found among lacertid lizards. Furthermore, the development of body segments was in some instances inconsistent with the competitive hypothesis, the largest sex having relatively smaller trophic structures.
182 citations
References
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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.
218 citations
129 citations
Book•
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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