Sex Ratios, Sexual Selection, and Sexual Dimorphism in Quails

1980 ◽  
Vol 44 (1) ◽  
pp. 198 ◽  
Author(s):  
David E. Brown ◽  
R. J. Gutierrez
Keyword(s):  
Sexual Selection ◽  
Sexual Dimorphism ◽  
Sex Ratios

scholarly journals Models of sex-ratio meiotic drive and sexual selection in stalk-eyed flies

1999 ◽  
Vol 74 (3) ◽  
pp. 245-253 ◽  
Author(s):  
RUSSELL LANDE ◽  
GERALD S. WILKINSON
Keyword(s):  
Sexual Selection ◽  
Sexual Dimorphism ◽  
Sex Ratio ◽  
Sex Ratios ◽  
Meiotic Drive ◽  
Total Body Length ◽  
Complete Suppression ◽  
Male Character ◽  
Female Mating ◽  
Female Mating Preferences

Hypertrophied sexually dimorphic eye stalks have evolved independently in several families of Diptera, with the eyespan of males exceeding their total body length in some species. These structures function in intermale contests for territories and in mate attraction, the classical mechanisms of sexual selection. In the family Diopsidae, species with extremely exaggerated eye stalks and marked sexual dimorphism in relative eyespan also usually have strongly female-biased sex ratios in nature caused by X-linked meiotic drive, whereas species with relatively small eye stalks have little or no sexual dimorphism, often lack meiotic drive and have even sex ratios. We investigate the possible connection between sexual selection and sex-ratio meiotic drive by analysing a three-locus model for the evolution of female choice for a male character associated with meiotic drive. Both meiotic drive and the male character are X-linked and the female preference is autosomal. Our model shows that suppressed recombination between meiotic drive and the male character, e.g. by inversion of the X chromosome, is necessary for sex-ratio selection to promote the origin of female mating preferences and exaggerated secondary sexual characters. With complete suppression of recombination, sexual selection reduces the frequency of meiotic drive, and may eliminate it. Very rare recombination, gene conversion or mutation, at rates characteristic of chromosome inversions in Drosophila, restores the meiotic drive polymorphism to its original equilibrium. Sex-ratio meiotic drive may thus act as a catalyst accelerating the origin of female mating preference and exaggerated male traits.

Sexual dimorphism and distorted sex ratios in spiders

Nature ◽  
1992 ◽  
Vol 360 (6400) ◽  
pp. 156-159 ◽  
Author(s):  
Fritz Vollrath ◽  
Geoff A. Parker
Keyword(s):  
Sexual Dimorphism ◽  
Sex Ratios

Sexual Selection and Sexual Dimorphism in Mottled Sculpins

Evolution ◽  
1983 ◽  
Vol 37 (1) ◽  
pp. 96 ◽  
Author(s):  
Jerry F. Downhower ◽  
Luther Brown ◽  
Ronald Pederson ◽  
Gloria Staples
Keyword(s):  
Sexual Selection ◽  
Sexual Dimorphism

scholarly journals Peak shifts and extinction under sex-specific selection

2021 ◽  
Author(s):  
Stephen P. De Lisle
Keyword(s):  
Sexual Selection ◽  
Sexual Dimorphism ◽  
Peak Shift ◽  
Adaptive Landscape ◽  
Population Estimates ◽  
Sexual Antagonism ◽  
Adaptive Landscapes ◽  
Quantitative Genetic ◽  
Complex Adaptive ◽  
The Face

AbstractA well-known property of sexual selection combined with a cross sex genetic correlation (rmf), is that it can facilitate a peak shift on the adaptive landscape. How do these diversifying effects of sexual selection +rmf balance with the constraints imposed by such sexual antagonism, to affect macroevolution of sexual dimorphism? Here, I extend existing quantitative genetic models of evolution on complex adaptive landscapes. Beyond recovering classical predictions for the conditions promoting a peak shift, I show that when rmf is moderate to strong, relatively weak sexual selection is required to induce a peak shift in males only. Increasing the strength of sexual leads to a sexually-concordant peak shift, suggesting that macroevolutionary rates of sexual dimorphism may be largely decoupled from the strength of within-population sexual selection. Accounting explicitly for demography further reveals that sex-specific peak shifts may be more likely to be successful than concordant shifts in the face of extinction, especially when natural selection is strong. An overarching conclusion is that macroevolutionary patterns of sexual dimorphism are unlikely to be readily explained by within-population estimates of selection or constraint alone.

Synthesis and Outlook

2021 ◽  
pp. 153-161
Author(s):  
Ingo Schlupp
Keyword(s):  
Sexual Selection ◽  
Mate Choice ◽  
Sex Ratios ◽  
Empirical Work ◽  
Male Mate Choice ◽  
Female Ornamentation ◽  
Female Quality ◽  
Investment In Reproduction ◽  
Selection Research ◽  
Male Mate

In this final chapter I want to briefly recap what I presented in the previous chapters and provide a few ideas on what might be done in the future to move the field forward. All three factors I discussed as relevant in male mate choice—male investment in reproduction, sex ratios, and variability in partner quality—are still emerging fields in sexual selection research and need more theoretical and empirical work. I suggest that variability in female quality is more important and more complex than currently known. The same is true for sex ratios. On the other hand, I suggest that sheer investment in gametes may be a little less important than currently assumed. Most importantly we need to explore the interactions of these three pathways to male mate choice. Female competition and also female ornamentation are still somewhat enigmatic and both topics are likely to grow in importance for our understanding of sexual selection. I think considering male and female choice together, as well as female and male competition will ultimately provide a more complete picture of Darwinian sexual selection.

Female and male costs of reproduction must be equal in dioecious Cape plant genus Leucadendron (Proteaceae)

2019 ◽  
Vol 67 (7) ◽  
pp. 517
Author(s):  
Jeremy J. Midgley ◽  
Adam G. West ◽  
Michael D. Cramer
Keyword(s):  
Sexual Dimorphism ◽  
Reproductive Output ◽  
Sex Ratios ◽  
Reproductive Allocation ◽  
Costs Of Reproduction ◽  
Male And Female

The Cape Leucadendron genus is dioecious, with extreme vegetative dimorphism displayed in some species – females having much larger leaves and fewer branches than males – whereas other species are monomorphic. Leucadendron is ecologically diverse, with some species with canopy stored seeds (serotiny) and others with soil stored seeds. These features mean that the Cape Leucadendron is an ideal genus to study the costs of reproduction for the different sexes in plants, and to determine whether vegetative dimorphism could be due to unequal costs. Here we use the unique aspects of the fire-prone Cape environment in which leucadendrons occur to show that the costs of sex must be equal between the sexes. Leucadendron populations are single aged because they only recruit after fires that kill all adults. Therefore, because the sexes have the same lifespans, they must have the same lifetime extent of vegetative versus reproductive allocation. Also, ecologically similar hermaphrodite Proteaceae co-exist with dioecious taxa. To co-occur, dioecious and hermaphrodite taxa must have the same mean post-fire fitness. This implies that dioecious females must have double the reproductive output that a co-occurring hermaphrodite has. This is only possible if the costs of reproduction are the same for the sexes and that the sexes use the same resources for reproduction. Finally, because males and female co-occur, they must be competitively equivalent to maintain natal sex ratios. These three factors suggest male and female allocate equivalently and therefore that vegetative sexual dimorphism is unlikely to be due to differences in allocation.

scholarly journals Sex differences in age-to-maturation relate to sexual selection and adult sex ratios in birds

2020 ◽  
Vol 4 (1) ◽  
pp. 44-53
Author(s):  
Sergio Ancona ◽  
András Liker ◽  
M. Cristina Carmona-Isunza ◽  
Tamás Székely
Keyword(s):  
Sex Differences ◽  
Sexual Selection ◽  
Sex Ratios

scholarly journals Sex ratio and sexual selection in wormshrimps (Crustacea, Amphipoda, Ingolfiellidea)

2006 ◽  
Vol 75 (03-04) ◽  
pp. 189-194 ◽  
Author(s):  
Ronald Vonk ◽  
Vincent Nijman
Keyword(s):  
Sexual Selection ◽  
Sexual Dimorphism ◽  
Sex Ratio ◽  
Habitat Use ◽  
Individual Species ◽  
Small Populations ◽  
Secondary Sexual Characters ◽  
Elusive Species ◽  
The Individual ◽  
Secondary Sexual

Small populations of several species of the groundwater dwelling amphipod genus Ingolfiella are found in caves, wells, seabottoms, beaches and riverbed interstitial habitats. To gain insight in the socio-ecology of these elusive species, we used data from collected specimens to explore the relationships between sexratios, display of secondary sexual characters and other morphological features, and habitat use. We extracted data on the sex ratios and the presence-absence of secondary sexual characters of 13 species from the literature and through examination of museum material. We found a clearly skewed sex ratio with a preponderance of females, both in the individual species as in the genus as a whole. However, sex ratio and the display of secondary sexual characters were not correlated, nor did these characters correlate with the amount of sexual dimorphism. It remains unknown why so many ingolfiellids have evolved these costly features.

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