L3- Kinship in social transitions

Question 1

how is coop breeding and eusociality developed

Answer 1

independent breeding is constrained ( shortage of territory for eg)

1- habitat saturation / ecological constraints)

grown offspring delay dispersal and stay at home

2- fitness benefits of helping exceed those of not helping (direct / indirect)

grown offspring help to rear later broods

Question 2

what are the direct and indirect benefits of coop breeding

Answer 2

direct fitness benefits

• current reproduction
• increased future survival and reproduction- eg acquisition of skills, group augmentation

indirect fitness benefits

• increased fitness of relatives
• better reproductivity or better survival of breeders

Question 3

what is the definition of
kin selection

Answer 3

selection on traits due to their beneficial effects on the fitness of relatives

Question 4

how does inclusive fitness hypothesis fit into origin of social groups- eusocialty
monogamy hypothesis

Answer 4

inclusive fitness= high relatedness played key role in transition to eusociality

monogamy hypothesis- strict lifetime monogamy results in individuals equally related to offspring and siblings (both r= 0.5),( if mother mates more then once, siblings no longer as related to eachother as would be offspring) any small net benefit from raising siblings rather than offspring will favour coop and potentially eusociality

Question 5

what are predictions of monogamy hypothesis

Answer 5

predictions
- all eusocial spp passed through a monogamy window
- multiple mating evolved later, following specialisation

Question 6

Have all eusocial spp gone through monogamy window?
has multiple mating evolved later, following specialisation (of sterile workers and helper ect)

Answer 6

in eusocial insects- all eusocial lineages have passed through an ancestral monogamy window, there are clades that exhibit polyandry, but workers are already specialised for helping

non-social organisms have cooperative transition to eusociality, as they have high relatedness as a result of strict lifetime monogamy in history

Question 7

does the monogamy hypothesis apply to other taxa, not just insects (mammals)

Answer 7

in mammals - cooperative behaviour results when females and males have equal reproductive skew (is reproduction shared in group, how many males and female reproduce) at around 100%, suggest monogamy and so high relatedness,

there is non-cooperative behaviour if there is low reproducing skew, more males reproducing eg, there is polygamy and so relatedness is lower

Question 8

does the monogamy hypothesis apply to other taxa, not just insects (birds)

Answer 8

there is less promiscuity in cooperative breeding birds, and higher in none cooperative. this means relatedness will be higher in coop species

( but still quite a lot of promiscuity in coop, there is little strict monogamy, less convincing then insects and mammals)

Question 9

is the hypothesis of coop breeding evolved in kin groups

Answer 9

one study found-
-found that 50% of coop species lived only with same-sex kin
-50% lived with mix of same-sex kin and non-kin
- 0% where coop mammals lived in groups with no relatedness
( study looked at kinship within same sex, helper males or helper females)

another study found-
In cooperative taxa ( 852 species in around 84 families)

-cooperation in non-kin groups
18% of avian families
8% of species
-cooperation in kin groups
82% of avian families
92% of species

• one study-
  213 well-studied coop breeding species
  55% helped in nuclear family groups
  30% helped in groups with mix of kin and non-kin
  15% lived primarily with non-kin

BUT these show correlational evidence not causation

Question 10

what is the confounding effects of territory and individual quality when looking at kin selection

Answer 10

productivity (foraging) increased with group size, but it could be due to increase in quality of pair or territory size

but when productivity between families with different helper size was compared in the same territories, when looked at same number of females but more male helpers, there was no effect of more helpers on productivity, WHEN looking at same territory with differing number of female helpers, female helper hindered productivity

Question 11

how has direct benefits of helping been under estimated

Answer 11

1-
paternity in fairy wrens
found kin selection was critical factor in evolution, but critical assumption in calculations assumed the relatedness between parents and offspring was high (males fathered all offspring), but fairy wrens perform sneaky copulations, 3/4 of offspring are favoured by males on other territories, extreme promiscuity

2- helpers of seychelles warblers assumed to be usually female non-reproductive and close kin (kin selection assumed to be important), in fact 44% of subordinates reproduce, and 40% of young result from extra-group paternity
kinship of helpers to brood. r= 0.13

Question 12

is there evidence for active kin discrimination

Answer 12

positive correlation found in bell miners birds, between relatedness and harder work. closer helper was related to brood, the more nest visits

• on a species level, across different species. in species where helpers on average are more closely related, do they invest / help more then species with low relatedness. But found it varied widely from species, but relatedness was positively correlated to helper effort