Sexual size dimorphism, diet, and reproductive biology of the Afro-Asian Sand Snake, Psammophis schokari (Psammophiidae)

2009 ◽  
Vol 30 (3) ◽  
pp. 331-340 ◽  
Author(s):  
Amanda Cottone ◽  
Aaron Bauer
Keyword(s):  
Body Size ◽  
Reproductive Biology ◽  
North Africa ◽  
Rainy Season ◽  
Sexual Size Dimorphism ◽  
Museum Specimens ◽  
Southwest Asia ◽  
Size Dimorphism ◽  
Males And Females

AbstractWe measured and dissected 226 museum specimens of Psammophis schokari (Schokari Sand Snake), a widespread, common “whipsnake” occurring in North Africa and southwest Asia. Three aspects of its ecology were investigated: sexual size dimorphism (SSD), diet, and reproductive biology. There was no significant SSD in mean body size or shape for the traits measured. The species is an opportunistic feeder, but preys predominately on lizards. Males and females exhibit their highest levels of sexual activity in synchrony and exhibit prenuptial spermiogenesis and a Type 1 vitellogenic cycle, respectively. Mating occurs at the end of the rainy season and clutch sizes are small. These findings from a Northern Hemisphere temperate sand snake are consistent with previous results for both tropical and south temperate Psammophis. These traits thus appear to be highly conserved within the genus and also exhibit convergence with respect to unrelated colubroid “whipsnakes”.

scholarly journals Bigger Males, Bigger Females? Pigeons’ Sexual Size Dimorphism

2020 ◽  
pp. 20-24
Author(s):  
P. M. Parés- Casanova ◽  
A. Kabir
Keyword(s):  
Body Weight ◽  
Body Size ◽  
Sexual Size Dimorphism ◽  
Wing Length ◽  
Rensch’S Rule ◽  
Size Dimorphism ◽  
Rensch's Rule ◽  
Neck Thickness ◽  
Males And Females ◽  
Domestic Pigeons

Sexual dimorphism, defined as phenotypic differences between males and females, is a common phenomenon in animals. In this line, Rensch’s rule states that sexual size dimorphism increases with increasing body size when the male is the larger sex and decreases with increasing average body size when the female is the larger sex. Domesticated animals offer excellent opportunities for testing predictions of functional explanations of Rensch’s theory. Pigeon breeds encounters many different functional purposes and selective constraints, which could influence strongly their morphology. The aim of this paper is to examine, for first time, Rensch’s rule among domestic pigeons. It was compiled a database of 12 quantitative traits (body weight, body height, beak thickness, beak length, neck length, neck thickness, wing length, rump width, tail length, tarsus length, tarsus thickness and middle toe length) for males and females of 11 different domestic pigeon breeds: Bangladesh Indigenous, Racing Homer, Turkish Tumbler, Indian Lotan, Kokah, Mookee, Indian Fantail, Bokhara Trumpeter, Bombai, Lahore and Hungarian Giant House; Rock Pigeon (Columba livia) was also considered as wild relative for comparative purposes. Comparative results between males and females showed that only body weight, wing length and neck thickness were consistent with Rensch’s rule. The rest of trait did not present correlations. Among domestic pigeons, there can appear different expressions of dimorphism according to each trait, so it must be considered that Rensch’s rule vary when considering other traits than body weight.

Reproductive biology of the false coral snake Oxyrhopus guibei (Colubridae) from southeastern Brazil

2002 ◽  
Vol 23 (4) ◽  
pp. 495-504 ◽  
Author(s):  
Otavio Marques ◽  
Lígia Pizzatto
Keyword(s):  
Body Size ◽  
Reproductive Biology ◽  
Rainy Season ◽  
Reproductive Activity ◽  
Climatic Conditions ◽  
Southeastern Brazil ◽  
Coral Snake ◽  
Males And Females ◽  
Reproductive Cycles ◽  
Number Of Individuals

AbstractThe reproductive biology of the false coral snake, Oxyrhopus guibei, was studied through dissection of 496 specimens, combined with observations on captive individuals. Males mature with smaller body size than females, females attain much larger body size, and male-male combat is not expected. Clutch size ranged from 3 to 20, and was correlated with female length. Reproductive cycles in both males and females seem to be continuous, with vitellogenesis and spermatogenesis occurring throughout the year. Reproductive activity in both sexes decreased at the end of the rainy season possibly due to previous intense reproductive activity in more favorable climatic conditions. The smaller number of individuals collected at the end of the rainy season apparently occurs due to the decrease of reproductive activity of this snake.

Egg size, prey size, and sexual size dimorphism in digger wasps (Hymenoptera: Sphecidae)

1985 ◽  
Vol 63 (9) ◽  
pp. 2187-2193 ◽  
Author(s):  
Kevin M. O'Neill
Keyword(s):  
Body Size ◽  
Selection Pressure ◽  
Sexual Size Dimorphism ◽  
Species Selection ◽  
Male Size ◽  
Size Dimorphism ◽  
Female Body Size ◽  
Mean Size ◽  
Males And Females ◽  
Apparent Association

Female digger wasps invest substantially in each of their offspring, laying relatively few, large eggs and providing the young with the insect prey on which they depend for food. In a study of six species in the genera Philanthus, Bembecinus, and Bembix, it was found that within each species, there is a positive correlation between female body size and both the size of their ovarial eggs and the size of the prey they provision. In five of the six species, females were larger than males on average. It is suggested that the apparent association between body size and certain aspects of parental investment by females may provide the directional selection pressure that results in the evolution of sexual size dimorphism in digger wasps. In one species, males and females have the same mean size, probably because, in this species, selection pressure on male size is similar to that on females.

Testing Rensch’s rule in Acanthoscelides macrophthalmus, a seed-feeding beetle infesting Leucaena leucocephala plants

2019 ◽  
Vol 97 (4) ◽  
pp. 304-311
Author(s):  
M.N. Rossi ◽  
E.B. Haga
Keyword(s):  
Body Size ◽  
Leucaena Leucocephala ◽  
Morphological Traits ◽  
Genetic Basis ◽  
Sexual Size Dimorphism ◽  
The Body ◽  
Rensch’S Rule ◽  
Size Dimorphism ◽  
Rensch's Rule ◽  
Males And Females

Rensch’s rule states that males vary more in size than females when body size increases. The main cause of Rensch’s rule has been credited to sexual selection. However, different degrees of plasticity between the sexes have also been proven to be useful for describing variations in sexual size dimorphism, particularly within an intraspecific context. For insects, in general, this rule has rarely been tested within species. Here, we tested whether Acanthoscelides macrophthalmus (Schaeffer, 1907) (Coleoptera: Chrysomelidae: Bruchinae) followed Rensch’s rule when individuals emerged from seeds immediately after fruit collection and when they were reared for one generation, by measuring three morphological traits. Rensch’s rule was not followed for any of the morphological traits. Variations in body size were similar in males and females for bruchines that first emerged from seeds and for those that were reared for one generation. These findings suggest that environmental conditions (e.g., temperature, humidity, and seasonality) are unlikely to drive differential plasticity in males and females of this seed-feeding beetle. It is possible that changes in the body size of A. macrophthalmus have a genetic basis. However, regardless of whether variations in body size have a genetic basis, our findings provide no support for Rensch’s rule.

Pattern of sexual size dimorphism supports the inverse of Rensch’s rule in two frog species

2014 ◽  
Vol 64 (1) ◽  
pp. 87-95 ◽  
Author(s):  
Di Lu ◽  
Cai Quan Zhou ◽  
Lian Jun Zhao ◽  
Wen Bo Liao
Keyword(s):  
Body Size ◽  
Sexual Size Dimorphism ◽  
Rana Temporaria ◽  
Rensch’S Rule ◽  
Size Dimorphism ◽  
Rensch's Rule ◽  
Frog Species ◽  
Mean Size ◽  
The Common ◽  
Males And Females

Rensch’s rule describes that sexual size dimorphism (SSD) increases with body size (hyperallometry) when males are larger, and decreases with body size (hypoallometry) when males are smaller. In this paper, on the basis of mean adult body size resulting from 18 populations of the common frogRana temporariaand 24 populations of the Tibetan frogNanorana parkeri, we tested the consistency of allometric relationships between males and females with Rensch’s rule. Our results show that the variation in degree of female-biased SSD increased with increasing mean size at intraspecific levels in two species, which is consistent with the inverse of Rensch’s rule. Furthermore, we tested the hypothesis that the degree of SSD decreased with increasing altitudes. Inconsistent with the predications of our hypothesis, we found no relationships between the degree of SSD and altitude for the two species investigated. These findings suggest that females living in adverse climates in high altitudes cannot adjust their body size as plastically as males.

Do Closely Related Species Influence Each Other's Sexual Size Dimorphism?

2018 ◽  
Author(s):  
Chloe Boynton
Keyword(s):  
Body Size ◽  
Related Species ◽  
Species Interactions ◽  
Sexual Size Dimorphism ◽  
Birds Of Prey ◽  
Closely Related Species ◽  
Size Dimorphism ◽  
Group I ◽  
Males And Females ◽  
Range Overlap

Size differences between males and females (sexual size dimorphism) are often seen in a variety of species. In birds of prey in particular, a phenomenon occurs where the female is larger than the male. One of the main hypotheses attempting to explain sexual size dimorphism in birds of prey is that the female and male differ in size to partition resources, like prey. There is also evidence that predator and prey body size are correlated, so predators of similar size may be in direct competition. It has been shown that when two closely related species interact in the same area, they are likely to be in competition for similar resources, like prey. This study is looking at sexual size dimorphism and closely related species interactions, which has never been looked at before in birds of prey. I am using the subfamily Buteoninae (Buteo Hawks) as my focal group. I will be using sexual size dimorphism ratios, estimates of genetic distance between closely related species and proportion of range overlap between different closely related lineages within the subfamily. I am expecting to see that if species are closely related and inhabit the same area they will have a decreased sexual size dimorphism. This is because both species are likely to be competing for the same resources, and to avoid competition the species will diverge in body size from one another. This will cause the male and female of each species to converge in size, reducing their sexual size dimorphism.

Measuring sexual size dimorphism in the yellow-pine chipmunk (Tamias amoenus)

2000 ◽  
Vol 78 (5) ◽  
pp. 728-733 ◽  
Author(s):  
Albrecht I Schulte-Hostedde ◽  
John S Millar
Keyword(s):  
Functional Analysis ◽  
Body Size ◽  
Sexual Size Dimorphism ◽  
Multivariate Methods ◽  
Size Dimorphism ◽  
Skeletal Tissue ◽  
Tamias Amoenus ◽  
Males And Females ◽  
Yellow Pine ◽  
The Difference

Body size was examined in the yellow-pine chipmunk (Tamias amoenus), which is reported to have female-biased sexual size dimorphism. Our objective was to determine if yellow-pine chipmunks from the Kananaskis Valley were dimorphic. Three methods were used. We compared body mass, 5 univariate components of body size, and multivariate centroids between males and females, and quantified measurement error. Females were significantly heavier (10-20%) and had a longer body (4%) and a longer (0.9%) and wider (2.2%) skull than male chipmunks, as well as being larger in overall size of skeletal tissue (structural body size). Multivariate methods such as discriminant functional analysis can robustly determine whether the sexes are significantly different in overall structural body size. However, univariate measures of body size provide an intuitively clear index of the magnitude of the difference in size of a particular character between the sexes.

Mating pattern, female reproduction and sexual size dimorphism in a narrow-mouthed frog (Microhyla fissipes)

2019 ◽  
Vol 69 (2) ◽  
pp. 247-257
Author(s):  
Guo-Hua Ding ◽  
Yun Tang ◽  
Zhi-Hua Lin ◽  
Xiao-Li Fan ◽  
Li Wei
Keyword(s):  
Body Size ◽  
Sexual Size Dimorphism ◽  
Dry Mass ◽  
Fertilization Rate ◽  
The Body ◽  
Mating Pattern ◽  
Female Reproduction ◽  
Size Dimorphism ◽  
Males And Females ◽  
The Difference

Abstract The difference in body size and/or shape between males and females, called sexual size dimorphism, is widely accepted as the evolutionary consequence of the difference between reproductive roles. To study the mating pattern, female reproduction and sexual size dimorphism in a population of Microhyla fissipes, amplexus pairs were collected, and the snout-vent length of males and females, female reproductive traits and fertilization rate were measured. If the body size of amplexed females is larger than that of amplectant males, this is referred to as a female-larger pair, a phenomenon that was often observed for M. fissipes in this study. Interestingly, snout-vent length of males in male-larger pairs was greater than that in female-larger pairs, however the post-spawning body mass, clutch size, egg dry mass and clutch dry mass did not differ between both types of pairs. Snout-vent length of males was positively related to that of females in each amplexus pair. After accounting for the snout-vent lengths of females, we showed that snout-vent lengths of males in male-larger pairs were greater than those of females in female-larger pairs. The snout-vent length ratio of males and females was not related to fertilization rate in each amplexus pair. The mean fertilization rate was not different between both amplexus pairs. These results suggest that (1) M. fissipes displays female-biased sexual size dimorphism and has two amplexus types with size-assortative mating; (2) the snout-vent length ratio of males and females in each amplexus type was consistent with the inverse of Rensch’s rule, and was driven by the combined effect of sexual selection and fecundity selection; (3) females with a larger body size were preferred by males due to their higher fecundity, while the body size of males was not important for fertilization success.

Body size, sexual size dimorphism, and Rensch's rule in adult hydropsychid caddisflies (Trichoptera: Hydropsychidae)

2003 ◽  
Vol 81 (12) ◽  
pp. 1956-1964 ◽  
Author(s):  
Jason E Jannot ◽  
Billie L Kerans
Keyword(s):  
Body Size ◽  
Sexual Size Dimorphism ◽  
Interspecific Interactions ◽  
Size Variation ◽  
Rensch’S Rule ◽  
Size Dimorphism ◽  
Selective Pressures ◽  
Rensch's Rule ◽  
Phylogenetic Inertia ◽  
Males And Females

Body size influences most biological processes from metabolic rates to the outcome of interspecific interactions. Within a species, sexual size dimorphism (SSD) reflects either differential selection on body size of males and females or phylogenetic inertia. Among taxa, SSD should decrease as body size increases when females are the larger sex — a pattern known as Rensch's rule. We examined body size, SSD, and Rensch's rule among 29 species of adult hydropsychid caddisflies (Trichoptera: Hydropsychidae) and 12 closely related caddisfly species. Females were almost always larger than males in all species examined. Body size variation among genera was greater than variance among species. In contrast, the greatest variance in SSD was among species within a genus. Contrary to Rensch's rule, the degree of SSD did not change as body size increased among genera. Observed body size patterns suggest that hydropsychid caddisfly species within a genus may be subjected to similar selective pressures during the larval stage, but this issue remains to be investigated. In addition, our data suggest that hydropsychids may violate Rensch's rule, a pattern not often reported. Our data provide a basis for proposing and testing hypotheses about the ecology and evolution of hydropsychid caddisflies.

Sign in / Sign up

Export Citation Format

Share Document