scholarly journals Macroevolutionary patterns of bumblebee body size: detecting the interplay between natural and sexual selection

2011 ◽  
Vol 2 (1) ◽  
pp. 46-57 ◽  
Author(s):  
Raúl Cueva del Castillo ◽  
Daphne J. Fairbairn
Keyword(s):  
Sexual Selection ◽  
Body Size ◽  
Natural And Sexual Selection

The manifestation and significance of sexual dimorphism in anguid lizards: a case study of Barisia monticola

1989 ◽  
Vol 67 (1) ◽  
pp. 68-72 ◽  
Author(s):  
James L. Vial ◽  
James R. Stewart
Keyword(s):  
Sexual Selection ◽  
Body Size ◽  
Reproductive Behavior ◽  
Reproductive Potential ◽  
Head Size ◽  
Adult Males ◽  
Allometric Growth ◽  
Natural And Sexual Selection ◽  
Dimorphic Expression

The dimorphic expression of body size, body – head size relationships, and chromatic characters among anguid lizards is reviewed. These characteristics are quantitatively examined in a population of Barisia monticola. No sexual differences are found in body size. Head size is positively correlated with body size; however, allometric growth rates in head size are significantly greater in adult males than in females or juveniles. Adult males also differ significantly in eight of nine chromatic characters, the most pronounced being the presence of light dorsal scale markings. These differences are explored in the context of both natural and sexual selection. We hypothesize that the absence of dimorphism in overall body size is the result of natural selection operating to maximize female reproductive potential. In contrast, we predict that dimorphism expressed in body – head size relationships and dichromatism are consequences of sexual selection relating to agonistic and reproductive behavior of males.

Size does not matter for male Marbled Salamanders (Ambystoma opacum)

2015 ◽  
Vol 93 (10) ◽  
pp. 735-740
Author(s):  
D.A. Croshaw ◽  
J.H.K. Pechmann
Keyword(s):  
Sexual Selection ◽  
Body Size ◽  
Reproductive Success ◽  
Large Male ◽  
Male Mating ◽  
Ambystoma Opacum ◽  
Positive Assortative Mating ◽  
Important Trait ◽  
Breeding Groups ◽  
Gravid Females

Understanding the phenotypic attributes that contribute to variance in mating and reproductive success is crucial in the study of evolution by sexual selection. In many animals, body size is an important trait because larger individuals enjoy greater fitness due to the ability to secure more mates and produce more offspring. Among males, this outcome is largely mediated by greater success in competition with rival males and (or) advantages in attractiveness to females. Here we tested the hypothesis that large male Marbled Salamanders (Ambystoma opacum (Gravenhorst, 1807)) mate with more females and produce more offspring than small males. In experimental breeding groups, we included males chosen specifically to represent a range of sizes. After gravid females mated and nested freely, we collected egg clutches and genotyped all adults and samples of hatchlings with highly variable microsatellite markers to assign paternity. Size had little effect on male mating and reproductive success. Breeding males were not bigger than nonbreeding males, mates of polyandrous females were not smaller than those of monogamous females, and there was no evidence for positive assortative mating by size. Although body size did not matter for male Marbled Salamanders, we documented considerable fitness variation and discuss alternative traits that could be undergoing sexual selection.

scholarly journals The physical environment mediates male harm and its effect on selection in females

2017 ◽  
Vol 284 (1858) ◽  
pp. 20170424 ◽  
Author(s):  
Li Yun ◽  
Patrick J. Chen ◽  
Amardeep Singh ◽  
Aneil F. Agrawal ◽  
Howard D. Rundle
Keyword(s):  
Drosophila Melanogaster ◽  
Sexual Selection ◽  
Physical Environment ◽  
Selective Advantage ◽  
Laboratory Studies ◽  
Male Choice ◽  
Female Fitness ◽  
High Quality ◽  
Evolutionary Consequences ◽  
Natural And Sexual Selection

Recent experiments indicate that male preferential harassment of high-quality females reduces the variance in female fitness, thereby weakening natural selection through females and hampering adaptation and purging. We propose that this phenomenon, which results from a combination of male choice and male-induced harm, should be mediated by the physical environment in which intersexual interactions occur. Using Drosophila melanogaster , we examined intersexual interactions in small and simple (standard fly vials) versus slightly more realistic (small cages with spatial structure) environments. We show that in these more realistic environments, sexual interactions are less frequent, are no longer biased towards high-quality females, and that overall male harm is reduced. Next, we examine the selective advantage of high- over low-quality females while manipulating the opportunity for male choice. Male choice weakens the viability advantage of high-quality females in the simple environment, consistent with previous work, but strengthens selection on females in the more realistic environment. Laboratory studies in simple environments have strongly shaped our understanding of sexual conflict but may provide biased insight. Our results suggest that the physical environment plays a key role in the evolutionary consequences of sexual interactions and ultimately the alignment of natural and sexual selection.

Sexual Selection and Body Size in Male Red-Winged Blackbirds

Evolution ◽  
1979 ◽  
Vol 33 (2) ◽  
pp. 649 ◽  
Author(s):  
William A. Searcy
Keyword(s):  
Sexual Selection ◽  
Body Size
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