Mate choice Flashcards
Female mate choice is a form of intra-sexual selection. True or false?
False, it is INTER-sexual selection
There are two kinds of female choice. What are they?
- Direct female choice
2. Indirect female choice
What is direct female choice based on?
Male morphology; fitness-dependent traits
Give 2 examples of attractive male traits.
- Dominance rank
2. Colouration
Colouration is particularly important to which species of primate?
Mandrills (closely related to baboons)
Mandrills are profoundly sexually dimorphic. What colours do males have on their faces, rump and genitalia?
Red, blue and violet
What is interesting about direct female choice in mandrills, which trait is most important to them? Who found this?
Colour is more important than dominance rank
Setchell, 2004
Setchell, 2004;
How do we know female mandrills prefer colour to rank? Give 3 examples.
- Colourful males are groomed most often
- Colourful males have the most successful mounts
- If a colourful male falls in rank, female attraction towards him does not change
Setchell, 2004
If a colourful male mandrill fell in rank, females continue to try and mate with him. Will he accept their solicitations? What does this suggest?
No, suggesting the dominance hierarchy is very important for male behaviour
What is indirect female choice based on?
Female morphology; ano-genital swellings
‘Any behaviour that restricts the chance of mating with certain individuals is said to be mate choice’. How does this relate to indirect female choice?
Although they do not actively discriminate, indirect female choice excludes some males from the mating pool
How does indirect female choice work?
It sets up competition between males. Whoever wins is seen as the better competitor and preferentially mated with
Which group have the largest sexual swelling of all primates?
Baboons
Why might mandrills rely more heavily on colouration than dominance rank for direct female choice?
Mandrills live in huge groups of up to 600 individuals, the composition of which is transient as individuals join and leave. Females do not always know the rank of a male, colour is a more reliable indicator of quality
When do females display sexual swellings?
In the periovulatory period
Highman et al., 2008;
What causes sexual swellings?
Hormones
What kind of information do sexual swellings convey?
Fertility information
Size and colour of swellings are the same in all females. True or false?
False, they vary between individuals and relate to the fertility of the female
Highman et al., 2008;
What does the size of the swelling correlate to? Which hormones are involved and what do they do?
Ovulation; oestrogen stimulates swelling and progesterone inhibits it, conveying messages about which stage of ovulation a female is in
What does swelling colour correlate to?
Parity
What is parity?
The number of times a female has given birth
In baboons:
Sexual swellings advertise female quality to males. Therefore females with the biggest swellings are the highest quality. True or false?
False:
It was found that swelling size increases with cycle number when it is unbroken by conception (Highman et al., 2008)
Why do males prefer older females?
They are more experienced mothers and it is more likely that their babies will survive.
Swellings are more likely to be graded signals. What does this mean?
Based on numerous variables, like cycle number and individual variation in ovulation and fertility.
Swellings are part of a wider network of signals. What 3 other factors contribute to indirect female choice?
- Olfactory cues
- Copulation calls
- Behavioural repertoires
Why might producing multiple signals by beneficial to the female? Explain how.
She can convey different information to different males and thus manipulate them differentially.
More dominant males may be allowed closer and so olfactory cues are important, whereas lesser males can only perceive visual signals.
How might a female benefit from differentially manipulating males?
She can assure or confuse paternity to prevent infanticide
There are 4 types of mate competition. What are they?
- Endurance rivalry
- Scramble competition
- Contest competition
- Reproductive suppression
In mate competition, what is endurance rivalry?
Remaining reproductively active for long periods
In mate competition, what is scramble competition?
Gaining access to mates before rivals do
In mate competition, what is contest competition?
Gaining mates by displays of quality or physical combat
In mate competition, what is reproductive suppression?
The production of socioendocrinological signals that prevent others from reproducing
Give an example of reproductive suppression.
In callitrichids the dominant female produces a pheromone that prevents her daughters from ovulating so they can allomother their siblings.
Mate choice can be pre or postcopulatory, as well as post-fertilisation. What is precopulatory choice?
A behaviour that restricts the probability of mating with particular partners
Mate choice can be pre or postcopulatory, as well as post-fertilisation. What is postcopulatory choice?
Females are able to select among the sperm in their reproductive tracts, choosing who the father will be
Mate choice can be pre or postcopulatory, as well as post-fertilisation. What is post-fertilisation choice?
Selection between zygotes, embryos or young produced by different males, produced by differential abortion or maternal investment
What is sexual coercion?
Forced mating that often results in harm to the recipient
What is ‘Fisherian Runaway Process’?
Large ornaments are costly for individuals yet they persist, as these individuals are more attractive and thus sire more attractive offspring that in turn will have a higher chance of mating
(sexy sons hypothesis)
What is the Genetic Indicator Hypothesis?
Ornaments are honest indicators of heritable quality
good genes hypothesis
Under the Genetic Indicator Hypothesis, what is the Handicap model?
Indicator traits are those that are costly and are thus considered as handicaps for the males producing them. These are selected for.
Under the Genetic Indicator Hypothesis, what can be said of host-parasite coevolution?
If handicaps demonstrate health, this shows parasite resistance
What is the Heterozygosity Hypothesis?
Females choose genetically dissimilar partners to increases heterozygosity in their offspring.
What is the Genetic Compatibility Hypothesis?
Females mate with multiple males to minimise the risk of mating with genetically incompatible sperm
In mate choice, the Fisherian Runaway Process, Genetic Indicator, Heterozygosity and Genetic Compatibility Hypotheses are examples of what? Why?
Mechanisms with indirect benefits to females, as females only acquire good genes for their offspring.
Mate choice that conveys direct benefits to females ensures what?
They get to share a male’s physical resources and thus increase their own survival/repro success.
The Fisherian Runaway Process, Genetic Indicator, Heterozygosity and Genetic Compatibility Hypotheses are all adaptive methods of mate choice. What does that mean?
The choosy sex (females) benefit
What are non-adaptive methods of mate choice?
The sex (females) do not benefit
What are the two methods of non-adaptive mate choice?
- Sensory bias
2. The Chase Away hypothesis
What is sensory bias?
(Male) traits are favoured because they exploit a pre-existing sensory bias in the female e.g. preference for a particular colour
What is the Chase Away Hypothesis?
Exaggerated traits that overcome female resistance to copulation are favoured as they exploit pre-existing sensory biases
Which sex is always the limiting resource to primate mating systems? Why?
Females, due to periods of ovulation
Basically males can mate all the time whilst females cannot
Why does selection favour choosy females?
So they can get the best genes for their offspring
Why is reproduction more costly for females?
Because of inter-birth intervals; females cannot immediately reproduce after giving birth, meaning they have a lower reproductive output than males who can reproduce continually
The ultimate goal is to maximise your reproductive output. True or false?
True, because it increases the transmission of your genes to the next generation
Sexual dimorphism indicates intra-sexual competition. Why?
Because males can be distinguished from females, meaning they use somatic competition to physically compete for female choice
In polygynous groupings, it is in the female’s interests to support the male. Why?
Because he can afford protection to her and her offspring.
When species have shorter mating seasons, females are more likely to have numerous/extra-group copulations. Why?
To ensure the fertilisation of her eggs.
In species with short mating seasons, why do males have larger testes?
Because the female is mating with multiple males, competition is in the sperm
Therefore, due to testes size and sperm competition, species with short mating seasons can be likened to what?
Polgynandrous and polyandrous groups
The slight sexual dimorphism of humans indicates what?
A historically polygynandrous society.
In species with scramble competition for mates, which kind of traits does sexual selection favour?
Speed or strong sensory perception, so males can find females before their competitors.
In these cases males do not need to be big or have large ornaments.
Females are more or less guaranteed to pass on their genes to the next generation whilst males are not. This is why strong competition between males exists. True or false?
True.
