Unit 2.4b Flashcards
What is monogamy?
It’s when a pair of animals mate to the exclusion of all others i.e. they mate for life
Why do animals often choose monogamy?
It means both parents are involved in parental care so offspring that require high levels of parental care receive this
How does monogamy benefit parents?
More viable offspring are produced as their parental care is provided for
Is this Schistosoma parasite monogamous?
Yes very, the female of the pair lives within a canal like structure of the body of the male
What is polygamy?
Is your umbrella term for individuals of one sex having more than one mate
What two categories can polygamy be divided into?
Polygyny and Polyandry
What is polygyny?
It is when one male mates exclusively with a group of females
In polygyny what are the roles of the male and females?
In mammals, the female is often the food source for young i.e. milk
The males often have a role of protecting, but not feeding
What is polyandry?
This is when one female mates with a number of males during the same breeding season
What is courtship?
It’s a specialised behaviour that attracts a member of the opposite sex and leads to mating
How do you courtship rituals increase the chance of sexual reproduction?
Animals use signals that only other members of the same species can understand. This could be giving of chemicals or making sounds or certain displays to initiate mating. This means that individuals can mate when they are most fertile.
What is a fix action pattern?
It is an instinctive behaviour sequence is relatively consistent within the species and will run to completion
What are fixed action patterns a series of?
They are a series of sign stimuli followed by responses
What is a sign stimulus?
This stimulus triggers fixed action pattern response in another individual of the species.
Are conspicuous physical traits in animals, beneficial or not?
It is both beneficial and negative for organisms, but in light of natural selection the benefits outweigh the negatives.
The negatives are that organisms are more visible to predators decreasing survival chances
The benefits are greater success in obtaining mates, i.e. higher fitness
What does sexual dimorphism usually refer to?
Physical difference between male and females of the same species. However, the males are usually larger have secondary sex structures (ie. Antlers) and are much more colourful than the females.
How did sexual dimorphism come to be?
Sexual selection
Why are females not usually coloured?
To increase the survival of her offspring as it reduces predation
What is reverse sexual dimorphism?
When the normally inconspicuous female is larger and more ornate than the male
Why are males often smaller in reverse sexual dimorphism?
Because they often have to travel long distances in search of females so smaller size means more speed and stealth
Why is it sometimes beneficial for mothers to be larger than the male?
If gestation and lactation, last for a few months, lodging mothers are able to provide for this better
What is an example of reverse sexual dimorphism?
Myotis bats have larger females as producing eggs has a much higher energy cost than producing male sperm. Female bats would also not be able to fly and catch prey if they were smaller as they need to support the mass of their offspring.
What are the two types of sexual selection that determine reproductive success?
Male-male rivalry
Female choice
What is male-male rivalry?
It is when males fight for dominance when acquiring and defending territories and mates, giving them access to females. They often use weapons like antlers, tusks and horns
What is an alternative that males take to mate instead of male-male rivalry?
Adopting the role of a ‘sneaker’ or ‘satellite’ male as this avoids engagement in direct conflict
Do males or females have primary control over reproduction?
Females
What are the three main male roles that play a part in female choice?
Male resources
Male appearance
Courtship displays
What does female choice allow the female to assess?
It allows them to assess how much parental care the male may offer
What does male courtship an appearance provide for the females?
Honest signals of male fitness. It indicates if it’s a healthy male with low parasite, burden, and the presence of any advantageous genes
Why do females like to choose the healthier/better males?
To increase their own fitness and reproductive success as they have to put a greater investment in reproduction so healthier offspring means less parental care
What is lekking?
It’s when males cluster in a communal display area (known as a leak) during breeding season where they can display themselves and fight each other to attract females. The females observe, and then select the fittest male to mate with.
How do you males arrange themselves in a lek?
Dominant males occupy the centre
Subordinates and juveniles at the fringes as ‘satellite’ males
