Natural selection

Question 1

Natural selection - how it works

def.

Answer 1

variation exists
some variation is heritable
species produce more offspring than can survive
individuals more suited = survive and reproduce
=change occurs within species
(if diversification is too great = new species are born)

def - differential selection of alternative alleles

Question 2

In genetic terms, natural selection is like…

Answer 2

all organisms have genes
genes passed on
many alleles (diff versions of same gene)
diff alleles cause diff development (more or less suited to environment)
allele that can survive and make copies of itself will replace other forms

Question 3

Gene- behaviour relationship studied via 2 methods?

Answer 3

1) mutagens (radiation/ chemicals to induce mutation)

2) studying natural variation in population

Question 4

Drosophilia used to look at how genes can influence behaviour – why?

Answer 4

24hr activity cycle mostly BUT some = 19hr cycle or 29hr
move around at random intervals (no cyclic pattern)
->differences arise from differenes in single gene known as ‘period gene’

Question 5

higher species?

warblers

Answer 5

migration behaviour in warblers = genetic components
if migration is prevernted = show restlessness at corresponding time
(selective breeding of migrating (M) and non migrating (nM) produced strains in offspring of both)

Question 6

Levels of selection:
individual
group

Answer 6

individual selection - try to out-compete

group selection - behave for group

Question 7

Wynne - Edwards invoked to explain:

Answer 7

threat displays - vs. dangerous fighting
population control - fecundity (ability to produce an abundance of offspring) adjusted so that species doesn’t over exploit avaliable resources
dominance hierarchies - dominant and submissive individuals = common feature of social organisation
(submission often = negative consequences fpr reproductive success…. so, why accept it? - pop. control)

Question 8

Group selection - whats wrong with it?

Answer 8

1) many traits evolve which are not to groups adv. (eg, infanticide - killing young)
2) cheats will always prosper
3) groups don’t go extinct fast enough

Question 9

Individual selection - whats wrong with it?

Answer 9

1) why are selfish individuals sometimes nice to the group?
2) why do birds lay less eggs than they can incubate? and why do individuals accept submissive status?
3) why are parents nice to their offspring?