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.
Citations
More filters
TL;DR: Caracteristiques des sites des Anolis des Antilles et des iles du Lac Gatun, Panama as discussed by the authors : A. Mortalite et A. Competition avec les oiseaux.
Abstract: Caracteristiques des sites des Anolis des Antilles et des iles du Lac Gatun, Panama. Competition avec les oiseaux. Mortalite. L'hypothese de Waide et Reagan selon laquelle l'abondance des A. est limitee par les predateurs, du moins sur les grandes iles, est rejetee
19 citations
TL;DR: It is suggested that co-occurrence is an important factor contributing to the enhancement of phenotypic variability and, consequently, to a trophic generalization at population level in G. baltica and I. insensibilis.
Abstract: We investigated patterns of resource partitioning between two brackish crustaceans (I. baltica and G. insensibilis) on trophic mosaics of fungal species colonizing vegetal detritus. Laboratory feeding experiments were carried out to assess consumption rates and diet selection of single individuals belonging to five populations. Adults of two co-occurring population of both G. insensibilis and I. baltica and one population of G. insensibilis, occurring alone in another habitat patch, were studied. Each individual were offered both fragments of Cymodocea nodosa conditioned by 8 fungal species and sterilized fragments as sole food source for 7 days. Both species preferred "conditioned" detritus but potential resource use was greater in G. insensibilis than in I. baltica. Individual niche breadth increased and phenotypic variability reduced in the allotopic sample. Trophic similarities were lower between individuals of co-occuring populations than between I. baltica and the allotopic G. insensibilis. The results suggest that co-occurrence is an important factor contributing to the enhancement of phenotypic variability and, consequently, to a trophic generalization at population level in G. insensibilis. It emphasizes the role of fungal patchiness on detritus in regulating resource partitioning between the two species.
18 citations
TL;DR: This study used the hypothetico-deductive method to evaluate multiple predictions from six hypotheses to understand the evolution and maintenance of SSD in horseshoe crabs and found little support for four hypotheses, but predictions for the fecundity advantage hypothesis were supported.
18 citations
TL;DR: It is indicated that intrasexual selection is a viable explanation of why male raccoons are larger than females because males are relatively larger for characters that relate to male-male combat.
Abstract: -Relative sexual dimorphism in measurements of 21 cranial dimensions of the raccoon (Procyon lotor) was analyzed using least squares regression analysis. Males were larger than females for all dimensions but were found to be larger than females for only seven such dimensions when controlling for skull size; females were relatively larger than males for 12 dimensions. This study indicates that intrasexual selection (male-male competition for access to females) is a viable explanation of why male raccoons are larger than females because males are relatively larger for characters that relate to male-male combat. However, it is also possible that sexual dimorphism in P. lotor is partly the result of intersexual selection (female "choice" of larger males). Although this study agrees with previous interpretations of sexual dimorphism in P. lotor, it points out the utility of examining relative patterns of sexual dimorphism before inferring the role of intrasexual selection.
18 citations
TL;DR: Statistical analysis indicates that in the ambushbug [Phymata americana (Melin), natural selection has favored disproportionately enlarged front legs (modified as claws used in capturing prey) in the larger sex, the females with the result that competition for prey between the sexes is reduced.
Abstract: Statistical analysis indicates that in the ambushbug [Phymata americana (Melin)], natural selection has favored disproportionately enlarged front legs (modified as claws used in capturing prey) in the larger sex ? the females ? with the result that competition for prey between the sexes is reduced. This disproportionate difference is shown to be due to sex differences rather than relative-size phenomena. Larger prey are taken in the field more readily by females than by males. In addition to the behavioral division of resources, males cease capturing prey earlier in the season, further reducing competition for food between the sexes.
18 citations
References
More filters
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)....
[...]
...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)....
[...]