Hypotheses

Question 1

Which hypotheses are associated with parental care?

Answer 1

• Parental Investment hypothesis (less investment in gametes–> less concerned about what happens to offspring)
• Low reliability of paternity hypothesis (certainty of paternity)
• Order of Gamete release hypothesis (females more likely to hold fertilised eggs esp. in internal fertilizing species- male can run off)
• Association with young hypothesis (females carry eggs to term so are more likely to increase fitness of them if she sticks around)

Question 2

Which hypotheses are associated with monogamy

Answer 2

• mate guarding hypothesis
• mate assistance hypothesis (e.g. altricial species- parental care can increase chance of survival)
• female enforced monogamy hypothesis (burying beetles and pheromones)

Question 3

Which factors effect mating systems?

Answer 3

• differential investment between the sexes (females more invested)
• dependence of young and impact of care (precocial vs altricial)
• certainty of paternity
• ecological factors- i.e. environmental potential for polygyny (uniform distribution of females leads to increased monogamy, aggregation leads to polygyny

Question 4

What are the 4 forms of polygyny?

Answer 4

1. female defence polygyny (males defend areas where females congregate and monopolise resources)
2. resource defence polygyny (males defend territories which have resources females require)
3. scramble competition polygyny (females widely dispersed, males scramble to maximise number of mates)
4. Lek polygyny (aggregation of males that display to females)

Question 5

Which hypotheses are associated with male reason behind Lek formation?

Answer 5

1. hotspot hypothesis- cluster around routes or places frequented by females
2. hotshot hypothesis- subordinate males gather around attractive dominant male
3. female preference hypothesis-males cluster because females prefer sites with larger groups of males

Question 6

What is a proximate cause for cooperative breeding?

Answer 6

juvenile delayed dispersal

Question 7

What are the direct and indirect benefits for cooperative breeders?

Answer 7

Direct:

• benefits of group membership
• gain breeding experience
• territory or mate inheritance
• participate in reproduction

Indirect
-helpers can adjust amount of help depending on relatedness

Question 8

What constraints have lead to the evolution of cooperative breeding?

Answer 8

Ecological:

• shortage of territories
• shortage of mates
• high dispersal costs
• low success in breeding independently

Life history :

• delayed maturity
• low adult mortality
• no or limited dispersal
• low reproductive rate

Question 9

What pre-copulatory mechanisms of sexual selection exist?

Answer 9

• intra sexual: same sex competition- sexual weapons, outcompete rivals, fighting
• intersexual: mate choice- female choice v powerful, nuptial gifts e.g. oral or seminal gifts.

Question 10

what post-copulatory mechanisms of sexual selection exist?

Answer 10

• sperm competion- mate guarding, removing rival sperm

- Cryptic female choice-females use physical or chemical mechanisms to control a males success in inseminating her eggs

Question 11

What is direct reciprocity? Give example

Answer 11

increases fitness of the cooperator and the recipient
-mutually beneficial behaviour
Cleaner Wrasse- cleans parasites from larger fish mouth
-gains a meal, and the larger fish is cleared of ectoparasites

Question 12

What are altruistic behaviours and give example

Answer 12

benefits recipient but not cooperator
can be explained by continued interactions over long time period
e.g. vampire bats
blood sharing, regurgitate blood to individual that was not successful at finding food to prevent them from starvation
-individuals cooperate on first interaction and i’ts subsequent interactions copies behaviour of other individual–> may gain benefit in future that is greater than cost

Question 13

What is indirect reciprocity

Answer 13

apparent altruistic behaviours where benefits come later, cooperator can gain reputational benefits which makes altruistic behaviour worthwhile in the long term

Question 14

Reasons for evolution of cooperation?

Answer 14

• kin selection- traits favoured because of their beneficial effects on the fitness of relatives
• indirect fitness benefits- helping your relatives allows cooperation to spread their genes without necessarily having to reproduce themselves
• hamiltons rule- coop genes should increase in freq when benefits of cooperating are greater than the costs depending on the level of relatedness: rB- C > 0

Question 15

Examples that show kin recognition?

Answer 15

tiger salamander: 2 types can develop, cannibals or invertebrate feeders. Experimentally manipulated into group- cannibalism occurred significantly later in kin associations–> some form of kin recognition
Shoaling in guppies: females produce broods with mixed paternity–> found that full siblings spent more time shoaling together and swarm closer together than half siblings

Question 16

Possible mechanisms of kin recognition?

Answer 16

1) Environmental cues- learn cues that identify APPARENT kin- acoustic cues, appearances, odour, or treat those sharing their environment as kin. e.g. long tailed tits, recognise kin based on song cues learnt in nesting period. who SHOULD be a kin not who is
2) phenotype and self referent matching: individual learns own phenotype and those of kin e.g. golden hamsters investigate non-kin sooner and for longer with no prior exposure
3) Green beard effect- individuals preferentially direct cooperative behaviours to others sharing a distinct genetic marker

Question 17

Example of cooperation leading to increase in inclusive fitness

Answer 17

Cooperation can evolve when the direct and indirect benefits to the cooperator outweigh the costs of performing cooperative behaviour:
-Cooperative courtship in turkeys
-male turkeys either court solo or in coalition with 1 dominant, 1 subordinate
subordinate- kin selection:
-high levels of relatedness between dom and sub
-measurable benefit to having sub, dom has more mating
-coop has cost to reproduction of sub
-meets hamiltons rule