Mating Strategy and Reproductive Success in the Teiid Lizard, Ameiva Plei

Behaviour ◽  
1995 ◽  
Vol 132 (7-8) ◽  
pp. 529-557 ◽  
Author(s):  
Ellen J. Censky
Keyword(s):  
Sexual Selection ◽  
Natural Selection ◽  
Reproductive Success ◽  
Sexual Size Dimorphism ◽  
Size Dimorphism ◽  
Large Size ◽  
Trade Offs ◽  
Males And Females ◽  
Current Selection ◽  
Growth And Reproduction

AbstractCurrent selection on sexual size dimorphism was studied in a widely foraging non-territorial lizard, Ameiva plei. Males were significantly larger than females. Large males won intrasexual agonistic encounters and guarded females during their entire receptive period (1-4 days). Guarding males spent significantly less time foraging than males who were alone. Only males that guarded females were observed to mate. Mating success was highly skewed with only six of 21 mature males in the study site observed mating. All six males who mated were 141 mm SVL (males mature at 62 mm SVL). The four largest males obtained 84% of all observed matings and were estimated to have fertilized 88% of the eggs. Sexual selection appears to favor large size in males due to competition among males to guard females. Large females on Anguilla also had higher reproductive success bccause SVL was positively correlated with clutch size and number of clutches in a season. It appears that natural selection has favored different trade-offs between growth and reproduction in males and females.

scholarly journals Solitary meat-eaters: solitary, carnivorous carnivorans exhibit the highest degree of sexual size dimorphism

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Chris J. Law
Keyword(s):  
Sexual Selection ◽  
Natural Selection ◽  
Social System ◽  
Sexual Size Dimorphism ◽  
Social Systems ◽  
Comparative Methods ◽  
Tree Of Life ◽  
Phylogenetic Comparative Methods ◽  
Size Dimorphism ◽  
Niche Divergence

Abstract Although sexual size dimorphism (SSD) is widespread across the animal tree of life, the underlying evolutionary processes that influence this phenomenon remains elusive and difficult to tease apart. In this study, I examined how social system (as a proxy for sexual selection) and diet (as a proxy for natural selection) influenced the evolution of SSD in terrestrial carnivorans (Carnivora; Mammalia). Using phylogenetic comparative methods, I found that are territorial solitary and carnivorous carnivorans exhibited selection towards increased degree of male-biased SSD compared to other carnivorans with alternative social systems and diets. I also found the absence of Rensch’s rule across most carnivoran clades, suggestion a relaxation of the influences of sexual selection on SSD. These results together suggest that sexual selection and niche divergence together are important processes influencing the evolution of male-biased SSD in extant terrestrial carnivorans.

scholarly journals Degree of anisogamy is unrelated to the intensity of sexual selection

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Judit Mokos ◽  
István Scheuring ◽  
András Liker ◽  
Robert P. Freckleton ◽  
Tamás Székely
Keyword(s):  
Sex Differences ◽  
Sexual Selection ◽  
Life History ◽  
Parental Care ◽  
Sex Roles ◽  
Sexual Size Dimorphism ◽  
Ecological Factors ◽  
Size Dimorphism ◽  
Wide Range ◽  
Males And Females

AbstractMales and females often display different behaviours and, in the context of reproduction, these behaviours are labelled sex roles. The Darwin–Bateman paradigm argues that the root of these differences is anisogamy (i.e., differences in size and/or function of gametes between the sexes) that leads to biased sexual selection, and sex differences in parental care and body size. This evolutionary cascade, however, is contentious since some of the underpinning assumptions have been questioned. Here we investigate the relationships between anisogamy, sexual size dimorphism, sex difference in parental care and intensity of sexual selection using phylogenetic comparative analyses of 64 species from a wide range of animal taxa. The results question the first step of the Darwin–Bateman paradigm, as the extent of anisogamy does not appear to predict the intensity of sexual selection. The only significant predictor of sexual selection is the relative inputs of males and females into the care of offspring. We propose that ecological factors, life-history and demography have more substantial impacts on contemporary sex roles than the differences of gametic investments between the sexes.

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

Absence of Trade-Offs Between Sexual Size Dimorphism and Early Male Emergence in a Butterfly

Ecology ◽  
1993 ◽  
Vol 74 (5) ◽  
pp. 1414-1427 ◽  
Author(s):  
Soren Nylin ◽  
Christer Wiklund ◽  
Per-Olof Wickman ◽  
Enrique Garcia-Barros
Keyword(s):  
Sexual Size Dimorphism ◽  
Size Dimorphism ◽  
Trade Offs

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.

scholarly journals Sexual selection and sexual size dimorphism in animals

2021 ◽  
Vol 17 (9) ◽  
pp. 20210251
Author(s):  
Tim Janicke ◽  
Salomé Fromonteil
Keyword(s):  
Sexual Selection ◽  
Sex Difference ◽  
Positive Relationship ◽  
Sexual Size Dimorphism ◽  
Effect Sizes ◽  
Size Dimorphism ◽  
Bateman Gradient ◽  
Mixed Support ◽  
Evolutionary Force ◽  
Length Measurements

Sexual selection is often considered as a critical evolutionary force promoting sexual size dimorphism (SSD) in animals. However, empirical evidence for a positive relationship between sexual selection on males and male-biased SSD received mixed support depending on the studied taxonomic group and on the method used to quantify sexual selection. Here, we present a meta-analytic approach accounting for phylogenetic non-independence to test how standardized metrics of the opportunity and strength of pre-copulatory sexual selection relate to SSD across a broad range of animal taxa comprising up to 95 effect sizes from 59 species. We found that SSD based on length measurements was correlated with the sex difference in the opportunity for sexual selection but showed a weak and statistically non-significant relationship with the sex difference in the Bateman gradient. These findings suggest that pre-copulatory sexual selection plays a limited role for the evolution of SSD in a broad phylogenetic context.

scholarly journals Sexual selection explains Rensch's rule of allometry for sexual size dimorphism

2007 ◽  
Vol 274 (1628) ◽  
pp. 2971-2979 ◽  
Author(s):  
James Dale ◽  
Peter O Dunn ◽  
Jordi Figuerola ◽  
Terje Lislevand ◽  
Tamás Székely ◽  
...  
Keyword(s):  
Sexual Selection ◽  
Sexual Size Dimorphism ◽  
Bird Species ◽  
Confounding Factors ◽  
Allometric Relationship ◽  
Rensch’S Rule ◽  
Size Dimorphism ◽  
Rensch's Rule ◽  
Clear Solution ◽  
General Explanation

In 1950, Rensch first described that in groups of related species, sexual size dimorphism is more pronounced in larger species. This widespread and fundamental allometric relationship is now commonly referred to as ‘Rensch's rule’. However, despite numerous recent studies, we still do not have a general explanation for this allometry. Here we report that patterns of allometry in over 5300 bird species demonstrate that Rensch's rule is driven by a correlated evolutionary change in females to directional sexual selection on males. First, in detailed multivariate analysis, the strength of sexual selection was, by far, the strongest predictor of allometry. This was found to be the case even after controlling for numerous potential confounding factors, such as overall size, degree of ornamentation, phylogenetic history and the range and degree of size dimorphism. Second, in groups where sexual selection is stronger in females, allometry consistently goes in the opposite direction to Rensch's rule. Taken together, these results provide the first clear solution to the long-standing evolutionary problem of allometry for sexual size dimorphism: sexual selection causes size dimorphism to correlate with species size.

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