Chapter 5: Female Reproductive Strategies in Non-Human Species
1. R vs K Reproductive Strategies
a. Courtship and epigamic selection
i. Considering the fact that female mammals make a minimum
possible investment in their offspring, she needs to choose her
mate wisely.
ii. Most animals engage in courtship rituals, with the male trying to
sell himself and the female acting as a choosy “shopper.”
iii. the process where she picks and chooses the best mate for herself,
she is controlling the process of sexual dimorphism.
b. Organisms have two different reproductive options: either have a great
number of offspring, but provide minimum to no parental care nor
investment or have few offspring, but provide a great amount of parental
care and investment.
c. The higher the number of offspring and the lower the parental investment,
the higher the offspring mortality. On the other hand, due to increased
parental care, the offspring survive longer.
d. R: multiple offspring, limited parental investment, high mortality
e. K: limited offspring, great parental investment, low mortality
f. humans: ultimate k strategist. Commit up to 18 years of efforts to raise
their offspring
2. Evolution leading to K-Strategists
a. At first, there were only r-strategists with asexual cloners, that provided no
parental care.
b. They became sexual reproducer r-strategists.
c. After, reptiles evolved on land and began laying eggs that evolved to have
hard shells to avoid being dried up.
d. The hard exterior of these eggs prevented sperm penetration, so
fertilization had to be done internally, which ultimately limited the number
of offspring.
e. Internal fertilization led to internal gestation and live births, which also
limited the number of offspring.
f. Finally, these social mammals developed skills and intelligence that they
passed on to each offspring.
3. Female Choosiness
a. When females have a choice in her mate, it is because in that particular
species the males are not aggressive, do not force the female into a
relationship and show secondary sexual characteristics-things that stand
out to the female such as colors, decorative behavior and courtship
displays.
b. A female must choose a mate, even when the characteristics are not
present in one occasion. She must use her cognitive skills to remember
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the characteristics she had seen in that particular male.
c. Females must be selective for choosing her mates for multiple reasons:
i. increase her reproductive success
ii. the likelihood of her offspring survival and access to resources.
Picking the right mate means ultimate access to resources, that
could potentially help her offspring survive as wella s increase her
reproductive success, which has proven to be favored in natural
selection.
d. It is important to note that the consequences that a male suffers from bad
mating is no where near what a female experiences. The male invests a
short time during copulation and provides the sperm, he does not spend
the time to nurture and raise offspring. More So, he could move on to
additional available mating possibilities, leaving the female with the
offspring.
Female Problems: Assessing Health, Genes and Behavior
a. Solution: Looking for Good Genes
i.
Females have evolved to be attracted to good genes. Signs of
genetic fitness in males reflects their ability to survive and
reproduce, things that a female values greatly. Signs of good genes
include obvious physical cues and behavior. Females rely on
characteristics they can see, such as strength, age, health and
agility. Behavior cues would be portrayed with a larger, older
healthy male who defends his territory. This male will be more
attractive to the female compared to a smaller male who cannot
prove himself.
b. Solution: Looking for Signs of Good Health
i. Females are more susceptible to signs that indicate good health. If
a male is sick, a female would not consider him to be a good suitor.
Health is an important factor to a female because in order to
reproduce and take care of her offspring, she must live a long time
to do so. Thus, to be certain that her offspring would be as healthy
as possible, she needs a healthy mate that could potentially ensure
that the offspring would get those qualities. Observable factors in
males are great indicators of health, because these cannot be
faked, this can be called “honest advertising”. For a male to grow
and have a high level of attractiveness, he must acquire resources.
A male that fails to do so, is showing females that he does not have
resources to allocate.
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c. Solution: Looking for Good Behavior
i. Females use behavioral signs to further evaluate his gene quality.
These behavior signals are reflections of a male’s competence.
Birds that are not healthy are not going to be able to show good
behavior, therefore they are not wanted by females.
d. Solution: Getting Males to Compete (and Choosing the Winner)
i. Females are able to choose the best mate with the best quality by
creating competition among the males and then deciding the
winner. It is presumed that the healthier male would be the one to
win and therefore the female would be able to choose a healthy
mate. Thereby, by choosing the winner, with the healthier genes,
she is maximizing the chances that her offspring will be protected,
have resources and even inherit some of her mate’s great qualities.
e. Solution: Finding High Status Males Attractive
i. Ultimately, females aim to mate with high-status males. High status
differs per species and can range from dominance, ornamentation,
size, territory size, health etc… A male that has survived the rigors
of life will likely be more attractive to the female. It is possible that a
female mates with a lower-status mate, but that is often during
times where she is not fertile, rather she reserves those fertile times
to mates with high status to ensure her reproductive success
f. Solution: .Looking for Males that Other Females Find Attractive
i. Many females look to mate with males that are also wanted by
other females. This means that he has desirable traits that are
obvious to many and mating would him would be the best decision.
Females believe that it the traits that male has can be passed on to
her offspring then future females would be attracted to her sons
and she would end up with many grandchildren. This is also known
as the “sexy-son hypothesis.”
g. Solution: Avoid Incestusous Matings
Problem: Attracting Best Possible Mate
Problem: Divert Male Aggression
a. harassment can lead to stress
b. Solution: reduce aggressive signals with vulnerability
c. Solution: invest in offspring
I Securing Male Investment in Offspring
a. Solution: Find resource-rich males attractive
i. willingness to give resources reflects his ability to parent
b. Solution: Find good father behavior attractive
i. behavior reflects whether they would be good fathers
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c. Solution: Enforce Long courtship before copulation
i. test commitment
d. Solution: Solicit gifts
i. willingness to give out resources is a good sign that he will provide
for offspring in the future
e. Sneaky Solutions: Cuckoldry
f. Sneaky Solutions: Confusing Paternity
g. Sneak Solutions: Competing with Other Females
i. sexual
ii. direct harassment
iii. social status
Problem: Choosing Best Time for Pregnancy
h. Solution: Do not get pregnant during hard times
i. Solution: Space Pregnancies
Problem: Investing in Offspring
a. Solution: Weaning
b. Solution: Allocating resources among offspring
i. offspring with greater potential=given more resources