... Intersexual selection… Female Choice
Females may select for males
with traits that indicate their quality
... If none of this works - cheat
• Satellite strategies –
younger or “weaker”
males often position
strategically near an
attractive male, then
sneaking up on
females when the
large male is unattentive or otherwise
Gerontology - Michael Hoerger
... Average age someone in your position
is expected to live; varies widely
Female in Japan = 85 years
Female Sierra Leone = 36 years
At birth, the average American male
can expect to live to age 74.5; female
... Roles within the group
... other males for mating opportunities
Intersexual Selection (Female Choice): If
female reproductive success is not limited by
access to males, then females will be selective
about which males they mate with in order to
maximize the quality of the male’s reproductive
... 2. Big dominant male can coerce females to mate.
Yet it might also be in the interest of females
to do so, because of: genetic quality(?),
protection, better resources
a WORD version of the handout
... One feature of many species that is not easily explained by natural selection is sexual
dimorphism. = females & males differ phenotypically.
1. Male cardinals are bright red, while females are drab.
2. Male peacocks have massive tails and are brightly colored compared to females.
Why do th ...
... If one male has more offspring, other males have less,
because this is a is a zero-sum game within the male sex;
males don’t have more offspring on average
if all eggs would have been fertilized anyway, just greater variance.
... (2) Variation is influenced age, which often serves as a correlate for experience
or body size/size of fighting appendages
(3) That the strength of sexual selection – inferred from the degree of variance in
reproductive success – is most intense among males
... age and underlying endocrine condition in the human male
Mesomorphy may be an indicator of superior cardiac function
and metabolic health
• May be favored because they offered females greater protection
and had physical advantages in hunting
evolutionary theory of gender roles
... differences came from differences in parental
investment. This is investment by the parent
that increases the offspring’s chance of
survival at the cost of the parent’s ability to
invest in other offspring. The qualities and
behaviours that led to reproductive success
were different for males and fe ...
Recent research reveals
... different sexual strategies from the sex that invests less. It is clear that
females, most of the time (through anisogamy) invest more. As a result, the
following can be deduced:
female RS is limited by either male quality (good genes) or male
females will be highly selective bec ...
`Wingman` -- how buddies help alpha males get the girl
... alphas more often than other males, but not
necessarily at the same territory where they were
betas. Even when the local alpha slot was empty,
some betas moved to be helpers elsewhere rather
than take over the vacant position.
"Without being an alpha, there's essentially no
chance for these males to ...
... Guenons: (Blue Monkey) Small (12-20lbs), arboreal, omnivores,
live in troops of about 20 with one dominant male.
Larger sexual dimorphism due to competition among mating
Non-dominant males live solitary and will mate with wandering
females of a troop.
Large vaiation in facial patterns
Lecture43-PPT - UBC Psychology`s Research Labs
... • The finding that females outperform males in school
has led a number of writers to argue that there is a
“boy crisis” in the school system:
Lewin (1998): How boys lost out to girl power.
Kindlon & Thompson (1999): Raising cain: Protecting
the emotional life of boys.
Sommers (2000): The war agains ...
lecture 09 - sexual selection - Cal State LA
... - also advertize her reproductive value, as predicted by theory
of “honest signaling”
- females with larger swellings attained reproductive maturity at
at younger age, had more offspring, and more surviving kids
Result: males expend more effort fighting over, and spend
more time grooming, females wi ...
... visits then male pollen from yellow-flowered plants
should have gotten ¾ of reproductive success, since
they received ¾ of the visits.
¾ of the seeds did produce yellow flowered plants.
So male success was directly related to the access to
pollinators and where they delivered the pollen.
but seed pa ...
11 Big Fish, Little Fish
... their transport, why be large? Why not find a female fast
when still quite small and young and then hang on as a
simple source of sperm? Why work and feed, and grow
large and complex? Why not exploit the feeding female? All
her offspring will still be 50 percent you.
Indeed, this strategy is quite c ...
... Reeves’s muntjacs are mostly crepuscular, active during dawn and dusk, but some
individuals also display diurnal and nocturnal tendencies. In the wild, males keep
small, well-defended territories that overlap with surrounding female territories.
Males mark their territories with scent glands located ...
Sexual Selection and Courtship Behavior in Insects
... • As males evolve traits that manipulate females into
mating with them…
…females evolve traits to resist the male manipulation!
• Then males evolve new traits that manipulate females,
which is countered again by the females, etc.
Practice Midterm Solutions
... 6. Male and female yellow mice are crossed. Over several litters, a 2:1 ratio of yellow to wild-type (agouti)
pups were produced. If the symbol “Y” represents the allele associated with yellow body color, which symbols
below most accurately describe the genotypes of the offspring?
a) Yy and yy
b) Y ...
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.