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: The morphological variation between mainland and island localities could be related to the fact that these populations were isolated during the last maximum glacial period in southern Chile, a period in which geomorphologic and bioclimatic features of this area were modified forming the present archipelago.
Abstract: Liolaemus pictus is a widely distributed arboreal lizard species in southern Chile. Within this species, mainland and island subspecies have been described mainly based on external morphological characters, however, their diagnostic characters have not been accurately demarcated. We used both traditional and geometric morphometrics to study the morphological divergence in L. pictus subspecies. Since geographic isolation can be related to environmental variation (e.g., variation in abundance and richness of insects or fruits), we predict that the L. pictus morphology could vary in head shape between mainland and island localities.Our results show morphological divergence in all variables analyzed among the island and mainland localities. The traditional morphometric approach reveals differences between populations from the mainland and island localities, where the mainland populations show a larger head size. Geometric morphometric data indicate that the eye orbits of the island specimens are more extended than in the mainland specimens in the dorsal view; this is probably related to a different capacity of substrate used. Also, in the lateral view, the eye orbits are extended and the head shape is less dorso-ventrally compressed in the island locality than in mainland populations and the terminal mouth position is more posterior in island specimens. We suggest that the morphological variation between mainland and island localities could be related to the fact that these populations were isolated during the last maximum glacial period in southern Chile, a period in which geomorphologic and bioclimatic features of this area were modified forming the present archipelago.
24 citations
TL;DR: Results indicate that M. atacamensis, a species inhabiting the intertidal zone of the coast of northern Chile, exhibits sexual dimorphism, males being larger.
Abstract: Microlophus is a lizard genus of South-America which has many species with sexual size dimorphism. An ecologicalstudy was performed on M. atacamensis, a species inhabiting the intertidal zone of the coast of northern Chile. Thefollowing questions were addressed: (1) does M. atacamensis exhibit sexual dimorphism? (2) do individuals of differentage and sex segregate spatially? (3) do individuals of different age and sex use different type of microhabitat? and (4)do individuals of different sexes exhibit differences in thermoregulatory characteristics? The study was conducted indifferent localities from northern Chile, which include two types of rocky systems used by this species, a high and alow type. At the moment of lizard capture, type of microhabitat, height of perch, body, air and substrate temperatures,were recorded. Individuals were then measured and weighted, and separated by age class and sex. Results indicate thatthis species exhibits sexual dimorphism, males being larger. There were no intersexual differences in microhabitat usedand height of perch in the high type system, although adults and subadults were spatially segregated from juveniles. Inthe low type system adult females shared microhabitat with juveniles, a probable consequence of behaviors related tothe burying of eggs. There were no differences between sexes in thermal characteristics, and body temperature of lizardsshowed independence from external thermal conditions.Key words: Tropiduridae, Microlophus atacamensis , sexual dimorphism, thermoregulation, spatial segregation,Chile.
23 citations
TL;DR: Male-biased dimorphism in head and leg dimensions as well as coloration, together with higher rates of intrasexual aggression and courtship activity by blue males, are consistent with the hypothesis that sexual selection explains the evolution of sexual dimorphisms in C. murinus.
Abstract: We measured body dimensions and coloration and quantified the behavior of females and males of two color phases in the Bonaire whiptail, Cnemidophorus murinus, to begin addressing the ultimate caus...
23 citations
Cites background from "The Ecological Significance of Sexu..."
..., jaw and head size) may also evolve owing to sexual differences in use of food resources (Selander 1966; Schoener 1967; Fitch 1982; Shine 1989; Perry 1996)....
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TL;DR: There was a significant relationship between snout–vent length and testis volume during maturation and regression stages in males with both types of color patches, concluding that ventral color patches displayed by male T. semitaeniatus are closely associated with their reproductive cycles.
Abstract: We describe sexual dimorphism in coloration and the reproductive cycle in Tropidurus semitaeniatus, a widely distributed lizard species in the caatinga of northeastern Brazil. Yellow and yellow- and-black patches occurred on the ventral surface of the thighs and precloacal flap in 15 and 11 adult males, respectively. Thirteen reproductively active males (collected November to March) had ventral patches with intense pigmentation, contrasting with the faded pigmentation of these patches in two males during the maturation stage (collected in October) and in 11 individuals in regression phase (collected April to September). Thirty-six adult females, reproductively active and not, and 21 juveniles lacked ventral color patches. There was a significant relationship between snout-vent length and testis volume during maturation and regression stages in males with both types of color patches. We conclude that ventral color patches displayed by male T. semitaeniatus are closely associated with their reproductive cycles.
22 citations
Cites background from "The Ecological Significance of Sexu..."
...Other mechanisms, such as resource partitioning (Schoener, 1967; Schoener and Gorman, 1968; Shine, 1991) and fecundity selection (Shine, 1989, 1992; Olsson et al., 2002; Vidal et al., 2002) can also cause sexual dimorphism....
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TL;DR: It is concluded that sexual dimorphism in head size is not the result of diet partitioning but instead of differential growth patterns following sexual maturity in males and females.
Abstract: Hemidactylus turcicus is a small gekkonid lizard native to the Middle East and Asia that is known to exhibit sexual dimorphism in head size. Several potential explanations exist for the evolution and maintenance of sexual dimorphism in lizards. We tested 2 of these competing hypotheses concerning diet partitioning and differential growth. We found no differences in average meal size (volume) or in any single dimension of prey size for similarly sized males and females. Allometric patterns of increases in head size also were measured in males and females. We found that males exhibited a mixture of isometric and positively allometric patterns of head size increase, whereas females exhibited isometric and negatively allometric patterns. Thus, we concluded that sexual dimorphism in head size is not the result of diet partitioning but instead of differential growth patterns following sexual maturity in males and females.
22 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
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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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