Sexual Selection Flashcards
Natural is the primary mechanism of what?
Sexual selection.
Why do some birds have ornaments and colors that do not improve their survival ability?
This is due to sexual selection. These traits evolve from sexual selection.
Sexual selection increase the reproductive sucess of the individuals even in the expense of their survival.
(True or false?)
True
How does sexual selection come about?
(According to darwin’s theory?)
The challenge for males to access females lead to sexual selection
What are the two mechanisms of sexual selection?
Intersexual selection and
Intrasexual selection
What is intersexual selection?
Members of one sex choose the opposite sex.
What is intrasexual selection?
(Also known as competition)
Members of the same sex evoke selection on each other.
Describe the gametes of females and males?
Male: Abundant and motile
Females: Fewer, Highly nutritious, Larger and non-motile gametes.
What are limitations to reproduction in Females and Males?
- Males are limited by access to females.
- Females are limited to access of resoures to produce their large gametes.
What is anisogamy?
The fusion or union of two gametes which different in size and form.
It is a form of sexual reproduction.
Bateman’s Principle
(2 things)
- Females should be choosier than males due to their eggs being expensive. Females reproductive success is limited compared to females.
- Because females are choosier than males it will lead to greater variation in the reprodutive success of males.
What influences stronger effects of sexual selection?
Higher reproductive variance.
With stronger variance there will be sexually dimorphic traits that are exaggerated in the sex with the highest reproductive variance.
(true or false)
True
What is the characteristics of successful females?
- Will not take away reproduction opportunities from females.
- Results in smaller variance in reproductive success.
What is characteristics of a successful males?
- If receives a disproportionate share of reproduction they will take away reproduction opportunities from other males.
- Can potentially sire many offsprings.
- Leads to higher reproductive variation among males.
Parental care
(female biased)
- Female biased postzygotic investment.
Anisogamy
(female biased pre)
Female-biased prezygotic investment.
Sexual Dimorphism
Elaborated trait expression in males
Which sex have strong selection in aNISOGAMY?
Stronger selection on males.
Which sex have higher reproductive fitness and why?
Males due to them being under the most sexual selection due to mate selection of females.
Sexually dimorphic species. Give examples
Mandrills (brightly colored nose area and larger than females)
Triplewart seadevils ( males are much larger than female)
Elephant seals (Males have elephant nose)
Orange tip butterflies (have an orange tip)
Lions (males have busy head area)
Mandarin duck (same plumage but brightly colored males).
Peafowl ( Peacock male have large colored peak).
The degree and direct of sexual dimorphism can be explained by relative selection gradient of each sex.
(True or false)
True
When females provide parental care what happens?
(reproductive success varience?)
- Females become limited resoucre for males due to them being occupied with offsprings post-mating.
- Therefore the reproductive success varience in males will be higher.
In biparental care what happens?
(reproductive success varience)
- Male have a lower reproductive success varience as he does not put energy into making additional mating opportunities.
- This is where both sexes take care of the offspring.
What happens when males are the sole parental care giver?
(Reproductive success variance)
- Reproductive success will be larger in females
- Males are now the limiyed resource to females.
Male deers are able to retain females for a longer period in combat. What type of selection?
Pre-copulatory:
To monopolize harem and single female.
(Intrasepecific selection or competition)
What kind of selection is mate choice?
Mate selection between opposite sexes to gain either indirect or direct benefit.
WHat is the pre-copulation in intersexual selection?
Males display at leks
What is the post-copulation of intersexual selection?
Female reproductive morphology does not allow for sperm directly contacting the egg.
Why do females choose their mates than to choose at random or the first male they get in contact with?
- Direct benefit they get from male such as : protection, food and care for offspring.
- Indirect benefit: where they reap the benefit through their offspring.
Male choice originally evolved to facilitate adaptive choice for traits conferring a survival advantage.
(true of false?)
True
Genetically superior mates produce fittner offspring.
(What kind of infirect benefit is that?)
Good Gene
Females that mate with preferred fathers produce sons that will have high mating success.
(What kind of infirect benefit is that?)
Sexy son
Differences among males provide females with information on their genetic qualities of different males that can be inheritied by the offspring.
(Good gene or Sexy sonn?)
Good gene
Characteristics of good genes.
(3 characteristics).
- Genes that allow males to carry handicap traits but are still surviving.
- Genes that signal resistance to diseases.
- Genes that are more compatible with those of females.
Females choose an arbitary trait that provides no information on the male quality and do not reinforce the effects of natural selection.
Sexy son.
They choose the sexually attractive male in order to help males reproduce sucessfuly in the future.
Sexual selection is stronger than natural selection. But can lead to great extravagance that lead to death of the male.
(true or false?)
True
The ability of females to affect the likelihood of sperm fertilizing their eggs is called ?
Female choice.
When females mate with multiple males their sperm compete inside the female to access the egg. What is this called?
Sperm competition or male-male competition.
What causes sexual conflic?
When genetic interest do not aligned.
Sexual conflict results in an evolutionary arms race.
(True of false)
True
