U2)KA4) SEX AND BEHAVIOUR

Question 1

what is parental investment

Answer 1

• use of resources by a parent to benefit future existing offspring

Question 2

investing resources in offspring is costly, however what are the benefits

Answer 2

• can result in increased numbers of offspring and their improved chance of survival , thereby increasing the evolutionary fitness of the parent

Question 3

parental investment begins with the production og gametes. what is the inequality in the investment required here

Answer 3

sperm are produced in much larger numbers than eggs but each egg has a much larger energy store

Question 4

what is external and internal fertilisation

Answer 4

external - gametes are released directly into the environment
internal- gametes are released into the reproductive tract of the female

Question 5

costs and benefits of external fertilisation

Answer 5

costs

• chances of fertilisation are lower, so many gametes are required
• no opportunity for parental care
• few offspring survive

benefits

• no increased exposure to predation or parasites
• very large numbers of offspring can be produced

Question 6

costs and benefits of internal fertilisation

Answer 6

costs
- finding mate requires energy expenditure and direct transfer of gametes from one partner to another

benefits

• fewer eggs need to be released as chances of fertilisation are higher
• offspring can be retained internally
• higher offspring survival

Question 7

• what are r selected organisms

- what are their characteristics

Answer 7

• those that are said to be r selected tend to be small species that produce many offspring, each of which have a low chance of survival
• characteristics : smaller, short generation time, reproduce early and often only once, produce many small offspring each receiving low energy input and limited parental care , most offspring do not reach adulthood

Question 8

r selected species

- this is a successful evolutionary strategy for opportunistic species in ______ environments

Answer 8

unstable

Question 9

• what are k selected species

- what are their characteristics

Answer 9

• are larger, tend to be longer lived are more likely to be subject to intra specific competition for resources in stable environments
• characteristics : large, long lived, slow to mature, can reproduce many times, produce few larger offspring, each with high level parental care , many offspring have high probability of surviving to adulthood

Question 10

what are mating systems based on

Answer 10

how many mates an individual has during one breeding season

Question 11

polygamy

Answer 11

• when individuals of one sex have more than one mate
• polygyny - a male mates exclusively with a group of females
• polyandry-one female mates with a number of males in the same breeding season

Question 12

monogamy

Answer 12

• each individual only shares gametes with one other individual to the exclusion of all others

Question 13

what is courtship

Answer 13

courtship is behaviour that leads to breeding success

Question 14

many birds and fish show ritualised courtship behaviours

• what is this
• give an example

Answer 14

• a specific sign stimulus from one individual produces a fixed action pattern response in the other
  this type of response is instinctive and is through to vary little between members of the same species
• eg in courtship of the stickleback: the swollen belly of a female fish acts a sign stimulus for the male for the male to commence his zig zag dance

Question 15

if uninterrupted : a series of sign stimuli and fixed action patter responses lead the stickleback pair through the complete courtship to…

Answer 15

to the successful fertilisation of eggs

Question 16

imprinting and courtship : what is imprinting

Answer 16

• ## irreversible development process that occurs during a critical time period in young animals (the come to realise another (animal, thing,) as their parent

Question 17

how does imprinting increase fitness

how does it influence mate choice

Answer 17

• increases fitness through natural selection . as forming an attachment to a parent that is providing care increases survival chances
• can also influence mate choice later in life as offspring may select mates that resemble parental phenotypes

Question 18

what is lekking

Answer 18

• involves communal displaying by groups of males
• females visit the lek to asses males and select a suitable mate
• in lekking species , there can be alternative successful strategies for males : dominant males tend to be larger and occupy the centre of the lek. Subordinate and juveniles are at the fringes as satellite males attempting to intercept females at the periphery of the lek area