Sexual selection of male parental care in giant water bugs
... evolution of care behaviours. Paternal care may enhance male reproductive success through increased
mating opportunities, when females are attracted to the direct benefit of increased offspring survival .
Females that prefer caring males may also derive indirect genetic benefits, if the caring ma ...
Bateman`s principles and human sex roles - synergy
... of offspring (reproductive success [RS]) than females; (ii)
males showed greater variance in number of sexual partners (mating success [MS]) than females; and (iii) there
was a stronger relationship between RS and MS among
males than females (note, Bateman measured mating success as the number of pa ...
Microsatellite analysis of maternity and the mating system in the Gulf
... operating on females than on males constitutes the definitional basis of sex-role reversal in recent sociobiological
theory (Vincent et al. 1992). This reversal is thought to
result from a female biased operational sex ratio (OSR),
such that more females than males are available to mate at
any given ...
Chapter 11: Sex and Evolution
... such species. In particular, which gender has more variable mating success? What basic
asymmetry of life is responsible for this phenomenon and why?
Answer: Males typically have more variable mating success than females. Females cannot
increase their reproductive success by mating with many males be ...
Rapid evolutionary change in a sexual signal
... the very same elements of a signal that are preferred by
females and because of this sexual signals represent a
compromise between natural and sexual selection (Zuk
and Kolluru, 1998). Perhaps the best-known example of
this comes from túngara frogs where both females and
predatory fringe-lipped bat ...
sexually transmitted disease and the evolution of mating
... pathogens or parasites, females should be able to use sexual
signals as indicators of genetic quality. The Hamilton-Zuk
hypothesis proposes that host-parasite coevolution maintains
variation in heritable quality. More recently, much attention
has been focused on the related immunocompetence-handicap ...
Sexual Selection Revisited — Towards a Gender- Neutral
... females has received less attention. Later theoretical work has revealed
that Bateman’s result could be explained by both sexes mating randomly
(e.g. no mate choice or male competition) (see Gowaty and Hubbell, 2005).
Thus, differential variance in reproductive success between the sexes cannot alone ...
Sexually selected females in the monogamous Western Australian
... We do not know the mechanism of the observed sexual
selection on females, i.e. whether it is generated by intrasexual competition among females for males or by intersexual mate choice as a consequence of male preference
for large females. The answer to this question will call for
future, detailed be ...
Allee effect, sexual selection and demographic stochasticity
... n (as expected), but that the convergence was rather
slow. For n=50, we had p(n):90%, and for n= 10,
p(n) :75%. In this first case, there was no assumption
on the success of the matings.
Incompatibility between phenotypes was then considered, assuming two incompatible phenotypes in equal
average pro ...
Eating Disorders and Males - John Hunter Hospital School
... The information in this article is by no means intended as a substitute for medical advice from a qualified health practitioner. It does not
recommend any one treatment, therapy or medication. Please seek medical advice as different medications suit different individuals.
Sexual Selection - Evolutionary Biology
... • intersexual selection (generally seen as female choice)
• ‘whilst in the other the struggle is likewise between the individuals of the same
sex, in order to excite or charm those of the opposite sex, generally the females,
which no longer remain passive, but select the more agreeable partners’
Cat Behavior and Training - Cat Neutering and Behavior
... Millions of cats are destroyed across North America each year because there are far more cats born than homes available. A
single male cat can father many litters so that neutering of intact males is essential for population control. Although sexual
desire will be greatly reduced by castration, some ...
... and September. Both sexes are mature after one year but usually only older males breed as
younger males cannot compete. It was recorded that 60% of wild and captive females mate as
juveniles with litters being produced at 1 year old (Chapman and Feldhamer, 1983). Captive
males may also mate and fath ...
Summary of - DrMillsLMU
... adornments, whether to enhance sexual attractiveness or intimidate competitive males, have been
poorly studied among primates.
This review focuses on the relationships between occurrences of sexually dimorphic
visual traits in male anthropoids (i.e., monkeys, apes, and human beings) and the types of ...
Dusting Behavior - Digital Commons @ OWU
... related to sex and body size (Loizi et al. 2009 and Shannon et al. 2008). For
example, post-pubescent and adult African elephant males are more likely
than females to engage in chemosensory behaviors that could indicate
female reproductive receptivity, including investigation of urine and feces.
Sex roles and sexual selection
... found in his studies of Drosophila melanogaster that multiple copulations led to a greater increase in the number of
offspring produced in males than in females. Hence, he
concluded that there is a greater advantage for males in
copulating with several partners than there is for females,
leading to ...
Courtship role reversal and deceptive signals in the
... copulations for nuptial prey gifts. Females compete for male gifts within leks that are organized for a brief
period each evening before dark. Before hovering within leks, females swallow air, inflating expandable
pouches on the pleural margins of the abdomen. The result is a large saucer-like abdom ...
- White Rose Research Online
... paternity. Delayed sperm ejection by a female after a second
mating results in biased paternity in favour of the second male
compared to individuals with a shorter sperm retention time.
Thus, active regulation of the timing of sperm ejection could
provide a mechanism by which females select sperm fr ...
Sexual selection on forelimb muscles of western grey kangaroos
... Both sexes of the larger kangaroos and wallabies
(Macropodidae) have similar morphology but males
often have extremely well-developed musculature of
the arms and upper body. Can this difference in
degree of development be explained in terms of sexual
selection? The larger kangaroos and wallabies are ...
Social preferences based on sexual attractiveness: a female
... days each month just after parturition , at which time
they emit chemical cues that attract males and stimulate
male sexual activity . For the remainder of the time,
females are generally not receptive to mating attempts,
although insemination at this time can lead to successful
Mate Choice, Sexual Conflict, and Evolution of Senescence
... on to their offspring. Thus, if a female can choose
among males based on age, by choosing to mate with
an older male, she is more likely to pass on high-quality
viability genes to her offspring.
Theoreticians have examined the conditions under
which preference for old mates can evolve (Beck and
mate choice and its evolutionary consequences
... The ability to recognise potential mates and choose the best possible partner for
reproduction is of fundamental importance for most animal species. This thesis
presents studies of mate choice in marine snails of the genus Littorina, where male
precopulatory mate choice seems to be more predominant ...
... achieve vaginal penetration and the inability to maintain this degree of penile
rigidity until ejaculation. Penile diseases such as congenital malformation,
peyronie’s disease, priapism, phimosis and rarely cold abscess may interfere
with erectile function.
There are two classification that have bee ...
Does courtship behavior contribute to species
... isolating mechanisms. This is especially true in dense
populations where a substantial number of mating interactions may be initiated without female phonotaxis to calling
song, i.e., noncalling satellite and/or silent mate searching
strategies are more effective at high density (Cade and Cade,
Sexual coercion in animals is the use of violence, threats, harassment, and other tactics by males to help them forcefully copulate. Such behavior has been compared to sexual assault, including rape, among humans.In nature, males and females usually differ in reproductive fitness optima. Males generally prefer to maximize their number of offspring, and therefore their number of mates; females, on the other hand, tend to care more for their offspring and have fewer mates. Because of this, there are generally more males available to mate at a given time, making females a limited resource. This leads males to evolve aggressive mating behaviors which can help them acquire mates.Sexual coercion has been observed in many species, including mammals, birds, insects, and fish. While sexual coercion does help increase male fitness, it is very often costly to females. However, in spite of these costs, a possible benefit to the females is a chance to test the stamina of the males, so that only those with ""good genes"" will father their offspring. Sexual coercion has been observed to have consequences, such as intersexual coevolution, speciation, and sexual dimorphism.