scholarly journals Sex ratios, size distributions, and sexual dimorphism in the dioecious tree Ilex aquifolium (Aquifoliaceae)

1998 ◽  
Vol 85 (11) ◽  
pp. 1602-1608 ◽  
Author(s):  
Jose´ Ramo´n Obeso ◽  
Manuel Alvarez-Santullano ◽  
Rube´n Retuerto
Keyword(s):  
Sexual Dimorphism ◽  
Sex Ratios ◽  
Size Distributions ◽  
Ilex Aquifolium

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

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.

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

Size distributions and sex ratios of sharks caught by Oman's artisanal fishery

2009 ◽  
Vol 31 (2) ◽  
pp. 233-239 ◽  
Author(s):  
A C Henderson ◽  
J L McIlwain ◽  
H S Al-Oufi ◽  
S Al-Sheile ◽  
N Al-Abri
Keyword(s):  
Sex Ratios ◽  
Size Distributions ◽  
Artisanal Fishery

scholarly journals Developmental sexual dimorphism and the evolution of mechanisms for adjustment of sex ratios in mammals

2016 ◽  
Vol 1389 (1) ◽  
pp. 147-163 ◽  
Author(s):  
Elissa Z. Cameron ◽  
Amy M. Edwards ◽  
Laura M. Parsley
Keyword(s):  
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.

Prenatal sex ratios influence sexual dimorphism in a reptile

2003 ◽  
Vol 295A (2) ◽  
pp. 183-187 ◽  
Author(s):  
Tobias Uller ◽  
Mats Olsson
Keyword(s):  
Sexual Dimorphism ◽  
Sex Ratios
Sign in / Sign up

Export Citation Format

Share Document