2.4 Sex and Behaviour Flashcards
Unit 2: Organisms and Evolution
Why do females invest so much more energy into offspring then males?
They produce food-rich gamates and males produce tiny mobile gamates
What is External Fertilisation?
When the male and females gamates unite outside the females body
What is Internal Fertilisation?
When the male deposits his sperm directly into the females body
What are the benefits of Internal Fertilisation?
-Increased chance of successful fertilisation
-Fewer eggs are required
-Offspring can be retained internally for protection and development
-Higher chance of offspring survial
What are the costs of Internal Fertilisation?
-A mate must be located which requires energy expenditure
-Requires direct transfer of gamates from one partner to the other
What are the benefits of External Fertilisation?
Very large numbers of offspring can be produced
What are the costs of External Fertilisation?
-Many gamates are predated or not fertilised
-No or limited parental care so little offspring surive
Examples of r Selection species:
Mice, rabits, most insects, cone toads, octupus, any mass spawning animals
Examples of K Selection species:
Humpback whales, elephants, humans, some birds
What is Monogamy?
The mating of a pair of animals to the exclusion of all others
What is Polygamy?
Individuals of one sex have more than one mate
What is Polygyny?
One male mates exclusively with a group of females
What is Polyandry?
One female mates with a number of males in the same breeding season
What is a Sign Stimuli?
This is a trigger that provokes a behavioural response
What causes successful courtship behaviour in birds and fish?
Species-specific stimuli and fixed action pattern responses
What is a Fixed Action Potential?
This is on instinctive the behavioural sequence that is relatively invariant within the species and almost inevitably runs to completion
What are Fixed Action Patterns?
These are a series of sign stimulis followed by reponses
What is Sexual Selection?
This selects charactersitics that have little survial benefit for the indivdual, but increase their chances of mating
What is Sexual Dimorphism?
Females are generally inconspicuous and males usually have more conspicuous markings
What is an Honest Signal?
These can indicate favourable alleles that increase the chances of survival of offspring (fitness) or allow parasite burden suggesting a heathy individual
What is Female Choice?
This is when females access the honest signals of males and mate with the best
What are Lekking Species?
These are males that cluster at a communal display areas or lek - displaying and possibly fighting to attract females
Where do each male stand during a lek?
The domint males are in the middle and the satalite males are on the outside
What is Male-Male Rivalry?
Large size or weaponry increases access to females through conflict
