Sexual Size Dimorphism and Sibling Competition: Implications for Avian Sex Ratios

1991 ◽  
Vol 138 (3) ◽  
pp. 623-641 ◽  
Author(s):  
Hugh Drummond ◽  
Jose Luis Osorno ◽  
Roxana Torres ◽  
Cecilia Garcia Chavelas ◽  
Horacio Merchant Larios
Keyword(s):  
Sexual Size Dimorphism ◽  
Sex Ratios ◽  
Sibling Competition ◽  
Size Dimorphism

Sex ratios, mating behavior and sexual size dimorphism of the northern water snake, Nerodia sipedon

1995 ◽  
Vol 36 (5) ◽  
pp. 301-311 ◽  
Author(s):  
Patrick J. Weatherhead ◽  
Frances E. Barry ◽  
Gregory P. Brown ◽  
Mark R. L. Forbes
Keyword(s):  
Mating Behavior ◽  
Sexual Size Dimorphism ◽  
Sex Ratios ◽  
Nerodia Sipedon ◽  
Size Dimorphism ◽  
Water Snake ◽  
Northern Water Snake

Sex ratios, mating behavior and sexual size dimorphism of the northern water snake, Nerodia sipedon

1995 ◽  
Vol 36 (5) ◽  
pp. 301-311 ◽  
Author(s):  
P. J. Weatherhead ◽  
Frances E. Barry ◽  
Gregory P. Brown ◽  
M. R. L. Forbes
Keyword(s):  
Mating Behavior ◽  
Sexual Size Dimorphism ◽  
Sex Ratios ◽  
Nerodia Sipedon ◽  
Size Dimorphism ◽  
Water Snake ◽  
Northern Water Snake

scholarly journals Sexual size dimorphism and sex ratios in dragonflies (Odonata)

2005 ◽  
Vol 86 (4) ◽  
pp. 507-513 ◽  
Author(s):  
FRANK JOHANSSON ◽  
PHILIP H. CROWLEY ◽  
TOMAS BRODIN
Keyword(s):  
Sexual Size Dimorphism ◽  
Sex Ratios ◽  
Size Dimorphism

Population structure and the evolution of sexual size dimorphism and sex ratios in an insular population of Florida box turtles (Terrapene Carolina bauri)

1997 ◽  
Vol 75 (9) ◽  
pp. 1495-1507 ◽  
Author(s):  
C. Kenneth Dodd Jr.
Keyword(s):  
Sex Ratio ◽  
Sexual Size Dimorphism ◽  
Sex Ratios ◽  
Size Dimorphism ◽  
Terrapene Carolina ◽  
Key Population ◽  
Younger Age ◽  
Box Turtles ◽  
The Status ◽  
Using Data

Hypotheses in the chelonian literature suggest that in species with sexual size dimorphism, the smaller sex will mature at a smaller size and a younger age than the larger sex, sex ratios should be biased in favor of the earlier maturing sex, and deviations from a 1:1 sex ratio result from maturation of the smaller sex at a younger age. I tested these hypotheses using data collected from 1991 to 1995 on an insular (Egmont Key) population of Florida box turtles, Terrapene Carolina bauri. Contrary to predictions, the earlier maturing sex (males) grew to larger sizes than the late maturing sex. Males were significantly larger than females in mean carapace length but not mean body mass. Sex ratios were not balanced, favoring the earlier maturing sex (1.6 males: 1 female), but the sex-ratio imbalance did not result from faster maturation of the smaller sex. The imbalance in the sex ratio in Egmont Key's box turtles is not the result of sampling biases; it may result from nest placement. Size-class structure and sex ratios can provide valuable insights into the status and trends of populations of long-lived turtles.

Morphology and diet of two sympatric colubrid snakes, Chironius flavolineatus and Chironius quadricarinatus (Serpentes: Colubridae)

2008 ◽  
Vol 29 (2) ◽  
pp. 149-160 ◽  
Author(s):  
Otavio Augusto Vuolo Marques ◽  
Ronaldo Fernandes ◽  
Roberta Richard Pinto
Keyword(s):  
Foraging Behaviour ◽  
Sexual Size Dimorphism ◽  
Sympatric Species ◽  
Colour Pattern ◽  
Ontogenetic Variation ◽  
Brazilian Cerrado ◽  
Size Dimorphism ◽  
Snake Species ◽  
Dietary Ecology ◽  
Arboreal Habit

Abstract The morphometry and diet of two sympatric species of Chironius (C. flavolineatus and C. quadricarinatus) from Brazilian Cerrado are described. The two snake species differ in external morphology, as Chironius flavolineatus was the largest species (body, tail and eyes) whereas C. quadricarinatus the heaviest. Each species also showed marked sexual size dimorphism. In terms of dietary ecology, both species feed exclusively on frogs with a heavy preference for hylids and may have tendency to eat small items, as noticed in other colubrine species. These two snake species showed a brownish colour pattern and exhibited no ontogenetic variation, suggesting that juveniles and adults use similar substrates. Chironius flavolineatus and C. quadricarinatus present a semi-arboreal habit, with active foraging behaviour, feeding in the ground most of time. Chironius flavolineatus uses higher vegetation for resting and, based on morphological results, seems to be more arboreal than C. quadricarinatus.

Latitudinal clines in sexual selection, sexual size dimorphism, and sex‐specific genetic dispersal during a poleward range expansion

2021 ◽  
Author(s):  
Rachael Y. Dudaniec ◽  
Alexander R. Carey ◽  
Erik I. Svensson ◽  
Bengt Hansson ◽  
Chuan Ji Yong ◽  
...  
Keyword(s):  
Sexual Selection ◽  
Range Expansion ◽  
Sexual Size Dimorphism ◽  
Size Dimorphism ◽  
Latitudinal Clines

scholarly journals A uni- and multivariate analysis approach to reveal sexual size dimorphism in Iranian populations of Hypera postica (Coleoptera: Curculionidae)

Biologia ◽  
2015 ◽  
Vol 70 (9) ◽  
pp. 1228-1233 ◽  
Author(s):  
Ehsan Sanaei ◽  
Marjan Seiedy ◽  
Farzaneh Momtazi
Keyword(s):  
Body Size ◽  
Sexual Size Dimorphism ◽  
Egg Laying ◽  
Morphological Divergence ◽  
High Fecundity ◽  
Hypera Postica ◽  
Size Dimorphism ◽  
Female Body Size ◽  
Divergence Pattern ◽  
Iranian Populations

Abstract Body size dimorphism between genders is a commonly observed phenomenon in insects, usually manifested in larger female body size. Sexual Size Dimorphism (SSD) varies from species to species, the degree and direction influenced by certain evolutionary pressures. Intraspecific variation in SSD may also occur between populations. The Hypera postica (Gyllenhal, 1813) is a well-known alfalfa plant pest that shows a degree of morphological divergence in its populations. The female alfalfa weevils are very fecund and have a larger body size compared to males. To improve our knowledge on magnitude and direction of SSD in alfalfa weevil, we studied 200 specimens of H. postica from four Iranian populations (Karaj1, Karaj2, Tuyserkan and Jovein). 10 morphological variables from three external anatomic parts (pronotum, elytra and rostrum) and 45 ratio characters were statistically analyzed in order to determine the amount of SSD in Iranian populations. In addition we investigated for morphological divergence pattern in mentioned populations. The results of this study show that a low degree of morphological divergence occurs in Iranian populations. Measured variables indicate that the SSD pattern of H. postica is compatible with the Rensch’s rule, and is related to high fecundity of females and a lack of strong sexual selection. Also it is mentioned that the larger rostrum in females may correspond to its unique role in egg laying.

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