UNIT 2 - KA4 Flashcards
Greater investment by…
Greater investment by females
Female investment in non-mammals and mammals
Female investment in the egg structure in non-mammals or in the uterus and during gestation in mammals
What is parental investment
Parental investment is costly but increases the probability of production and survival of young
Characteristics of r - selected species (5)
- Smaller
- have a shorter generation time
- mature more rapidly
- reproduce earlier in their lifetime often only once
- produce a larger number of smaller offspring each of which receives only a smaller energy input
- limited parental care most offspring will not reach adulthood
Characteristic of K-selected species (6)
- larger and love longer
- mature more slowly
- can reproduce many times in their lifetime
- produce relatively few larger offspring
- high level of parental care
- many offspring have a high probability of surviving to adulthood
Which environments does r-selection occur in
r-selection tends to occur in unstable environments where the species has not reached its reproductive capacity
Where does K-selection occur
K-selection tends to occur in stable environments
Benefits of external fertilisation
Benefits : very large numbers of offspring can be produced
Costs of external fertilisation
Costs:
- many gametes predated or not fertilised
- no or limited parental care
- few offspring survive
Benefits of internal fertilisation
- increased chance of successful fertilisation
- fewer eggs needed
- offspring can be retained internally for protection and or development
- higher offspring survival rate
Costs of internal fertilisation
- a mate must be located
- which requires energy expenditure
- requires direct transfer of gametes from one partner to another
What are mating systems based on
Mating systems are based on how many mates an individual has during one breeding season
Monogamy
The mating of a pair of animals to the exclusion of all others
Polygamy
Individuals of one sex have more than one mate
Polygyny
One male mates exclusively with a group of females
Polyandry
One female mates with a number of males in the same breeding season
What do many animals have
Many animals have mate selection courtship rituals
What can successful courtship behaviour in birds and fish be a result of
Successful courtship behaviour in birds and fish can be a result of species specific sign stimuli and fixed action pattern response
What does sexual selection select for
Sexual selection selects for characteristics that have little survival benefit for the individual but increases their chance of mating
How do many species exhibit sexual dimorphism
Many species exhibit sexual dimorphism as a product of sexual selection
What are females generally
Females are generally inconspicuous
What do males have more of
Males usually have more conspicuous markings structures and behaviours
Which species does reversed sexual dimorphism occur in
Reversed sexual dimorphism occurs in some species
What does female choice involve
Female choice involves females assessing honest signals of the fitness of males
What can honest signals indicate
Honest signals can indicate favourable alleles that increase chances of survival of offspring (fitness) or a low parasite burden suggesting a healthy individual
Where do males gather lekking species
In lekking species males gather to display at a lek where female choice occurs
What do some bird species exhibit
Some bird species exhibit lekking behaviour
Where do dominant and satellite males occupy
Dominant males occupy the centre of the lek with subordinates and juveniles at the fringes as satellite males
When does female choice occur
During the display female choice occurs
What increases access to females for mating
Success in male - male rivalry through conflict (real or ritualised) increases access to females for mating
How do males fight for dominance and access to females
Males will fight for dominance and access to females, often using elaborate ‘weapons’ such as antlers, tusks , horns
