Kinship and Animal Behavior

1. 動物行為學 (通識) 05 親緣關係 (Kinship) 國立臺南大學 通識課程 2011年春 鄭先祐 (Ayo)教授 國立台南大學 環境與生態學院 生態科學與技術學系 環境生態研究所 + 生態旅遊研究所 Ayo NUTN Web: http://myweb.nutn.edu.tw/~hycheng/

2. 親緣關係 (Kinship) • 親緣關係與動物行為 • 親緣理論 • Relatedness and inclusive fitness • Family dynamics • 家庭的衝突 • Parent-offspring conflict • Sibling rivalry • 親緣辨識 • Matching models • Rule-of-thumb models of kin recognition

3. 親緣關係與動物行為 • Belding’s ground squirrels give alarm calls when a predator is spotted. • Alarm calls are most often emitted by females • Females are surrounded by relatives, while adult males are generally in groups that do not contain their genetic relatives • Belding’s ground squirrel groups are typically made up of mothers, daughters, and sisters who cooperate with one another in a variety of contexts. • Males that emigrate into such groups cooperate to a much smaller degree.

4. In Belding’s ground squirrels, females (A) are much more likely than males to emit alarm calls when predators are sighted. Such alarm calls warn others, including female relatives and their pups (B)

7. Homicide(殺人) in humans • 512 homicide cases occurring 1972 in Detroit, Michigan • 127 (25%) of these murders were committed denote as “relatives”. • However, the police classify in-laws, and even boyfriend-girlfriend pairs, as relatives, rather than limiting this category to genetic kin. • Only 6% of the murders involved relatives. • 倘若按相處時間計算其風險， (Table 8.1)

8. Genetic relatives rarely kill each other

9. 親緣理論 • The modern study of animal behavior and evolution began in the early 1960s, when W. D. Hamilton, one of the leading evolutionary biologists of the twentieth century, published his now famous papers on genetic kinship and the evolution of social behavior. • These papers formalized the theory of “inclusive fitness” or “kinship” theory and revolutionized the way scientists understood evolution and ethology.

10. A classic case of helping genetic relatives is that of mothers feeding their young. In bank swallows, young chicks remain at the nest, and mothers remember the location of their nests so that they can return after foraging to feed youngsters there

11. Relatedness and inclusive fitness • r = genetic relatedness • Inclusive fitness= direct + indirect fitness • Hamilton’s rule • ( ∑ r b)- c > 0 • b = the benefit • c = the cost accrued to the individual expressing the trait

13. The effects of helping kin • Using groups of gray-crowned bablers that ranged from an initial size of six to eight individuals, Brown and his colleagues removed all but one of the nonreproductive helpers from the experimental groups, while leaving the number of nonreproductive helpers in the control groups unchanged. • Reproductive success, as measured by the number of fledglings, was significantly lower in the experimental group because they had fewer helpers.

14. Using groups of gray-crowned bablers that range from an initial size of six to eight individuals. Brown and his colleagues removed all but one of the nonreproductive helpers from the experimental groups, while leaving the number of nonreproductive helpers I the control groups unchanged. Reproductive success, as measured by the number of fledglings, was significantly lower in the experimental groups because they had fewer helpers.

15. Family dynamics • The building blocks for family dynamics • Inclusive fitness (kin selection theory) • Ecological constraints theory • Reproductive skew theory • Biological families (4/15 hypotheses)

16. Biological families (4/15 prediction) • 1. Family dynamics will be unstable, disintegrating (破碎) when acceptable reproductive opportunities materialize (突然出現) elsewhere. • 2. Families that control high-quality resources will be more stable than those with lower-quality resources. Dynasties may form. • 4. Cooperative breeding will be expressed to the greatest extent between those family members that are the closest genetic relatives. • 9. Replacement mates (stepparents) will invest less in existing offspring than will biological parents.

17. Family dynamics (prediction 1) • 1. Family dynamics will be unstable, disintegrating(破碎) when acceptable reproductive opportunities materialize(突然出現) elsewhere. • This is the most basic prediction made by Emlen, as it focuses on fundamental costs and benefits associated with family life. • One technique for experimentally examining prediction 1 is to create new, unoccupied territories and examine whether mature offspring leave their natal area to live in such newly created areas. (Superb fairy wren) they did so, within 6 hours.

18. In superb fairy wrens, young males often act as helpers-at-the –nest. When Pruett-Jones removed breeding males from their territories, almost all potential male helpers who could have dispersed to newly opened territories did so.

19. In the superb fairy wren, male helpers often assist their parents. If a vacant territory opens up, however, male helpers are quick to leave the family unit and attempt to start their own family.

20. Family dynamics (prediction 2) • 2. Families that control high-quality resources will be more stable than those with lower-quality resources. Dynasties may form. • 案例：acorn woodpeckers • Territories varied from less than a 1,000 to greater than 3,000 storage holes for acorns. • Individuals on territories with lots of storage holes produced a greater average number of offspring • In the areas with more than 3,000 storage holes, 27%of the young remained on their natal territories and helped their relatives, while only 2% of the young on territories with fewer than 1,000 holes stayed.

21. In cooperatively breeding acorn woodpeckers, the young not only survive better on territories with more storage holes, they are also more likely to remain on their natal territories throughout their life, creating a “family dynasty”. Such dynasties enable kin groups to compete for superior territories.

22. Increasing territory size, and hence increasing number of storage holes, led to increase rate s of survival.

23. Prediction 2 to human family dynamics • Well-to-do families being more stable than poorer families? • If a stable family is defined in terms of co-residence, then this prediction is not supported. • Wealthier individuals did keep in touch with relatives more often than did lower-income individuals • High-income families are more likely to maintain social ties at some level and to engage in exchange.

24. Based on Emlen’s dynasty building hypothesis, Davis and Daly hypothesized that familial contact would be greater in wealthy human family units. The data from the 1991 Canadian General Social Survey support this general prediction.

26. Family dynamics (prediction 4) • 4. Cooperative breeding will be expressed to the greatest extent between those family members that are the closest genetic relatives. • 案例：white-fronted bee-eater kinship and helping close relatives

27. Inclusive fitness models of behavior have been tested extensively in white-fronted bee-eaters.

28. In white-fronted bee-eaters, individuals are more likely to help those to whom they are more closely related . For example, when interacting with genetic kin with r=0.5, birds dispensed aid 80 % of the time, but that percentage drops to less than 20% when r=0.125.

29. Haplodiploid genetic system • Honeybee policing • Haploid males; Females, diploid • (A) while the queen typically lays the eggs in the honeybee colony, workers also attempt to lay unfertilized eggs. • (B) when an egg laid by a worker is detected by worker police, it is eaten or destroyed. Such “ policing” has inclusive fitness benefits associated with it.

30. Honeybee policing • While the queen typically lays the eggs in the honeybee colony, workers also attempt to lay unfertilized eggs. • When an egg laid by a worker is detected by worker police, it is eaten or destroyed. Workers are much more likely to destroy eggs produced by other workers than eggs produced by the queen. Such “policing” has inclusive fitness benefits associated with it.

31. In honeybees, where queens often mate with ten to twenty males, workers are more related to the male offspring of the queen (their brothers) than to offspring of other workers (their nephews). Workers police the hive and search out and eat the eggs of other workers.

32. Wasp policing • The wasp in the middle of the photo is a worker who has just laid an egg. • here a worker is eating another worker’s egg. Policing is much more common in wasp colonies where the queen has mated with many males.

33. The more effective policing was at removing worker eggs, the less often workers attempted to reproduce.

34. Family dynamics (prediction 9) • 9. replacement mates (stepparents) will invest less in existing offspring than will biological parents. • Child abuse and genetic relatedness in humans • (A) two natural parents • (B) one natural and one stepparent

35. (A) The per capital rates of child abuse reported in 1980 by the American Humane Association in the United States. Rates of child abuse were significantly greater in households where one parent was not genetic kin.

36. (B) The same relationship between child abuse and family type was also uncovered in Canada, as reported in 1983 by a provincial registry in Hamilton, Ontario.

37. Conflict within families • Parent-offspring conflict • How much aid to give to any particular offspring? (parental investment) • 案例： • Parental investment and mating systems in primates • In-utero conflicts in humans • Sibling rivalry (對抗，競爭)

38. Parental investment and mating systems in primates The hypothesis: • offspring will attempt to extract more resources from patents in polyandrous systems than in monogamous systems. • Fetuses grew faster in utero (taking more maternal resources) in polyandrous primate species • Because sperm competition is more intense in polyandrous species, males in such species tend to have larger testes. • Testes size can often be used as a proxy for the degree of polyandry. • Fetal growth rate is positively corrected with the testes size.

39. Testes size tends to be larger in male from polyandrous vs. monogamous species. The relationship between testes size (a proxy measure of polyandry) and parent – offspring conflict (measured by fetal growth rate) was positive in analysis of primates.

40. Mothers and babies. While the patent-offspring relationship is usually cooperative (A), parent-offspring conflict can occur, even in utero as shown by an ultrasound (B)

41. Sibling rivalry • Sib-sib conflict. • Kin selection theory predicts that individuals generally should not be very aggressive toward kin such as sibs. • This is especially true when there are abundant resources. • But if there are limited resources, conflict over the resources will increases.

43. Sib-sib competition in egrets • They lay their eggs in sequence, rather than all at one time. Thus, hatching order produces chicks that can differ in age by many days. • Such age differences play a critical role in determining who emerges as the victor in sib-sib interactions, since chicks that hatch first start to feed sooner and hence receive more food, which leads to a weight advantage over chicks that hatch later • Large size means better fighting ability

44. In nests of egrets, sib-sib competition can be intense and result in the death of smaller, less dominant chicks. Sibling rivalry can be seen in the fights between siblings in the nest, as shown, where one of the chicks is preparing to bite its sibling on the back of its head.

45. Birth order and food intake (A) Normal broods of little blue herons include four to five chicks that are hatched asynchronously. The three eldest chicks (Chicks 1,2, and 3) are heavier than the youngest chicks (chicks 4 and 5). If younger chick is part of a brood in which one of its older sibs has died (lost sib), its average weight is less than that of its older sibs but more than it would be if it were in a brood in which no sibs had died (no loss).

46. (B) In egret broods, the oldest, dominant chick (1) receives more food than the middle chick (2), who in turn gets more than the youngest chick (3). This holds for the early period after hatching (1-13days), the middle period (14-21 days), and the late period (21-30 days).

47. Kin recognition • Kin recognition in penguins • Matching Model • Template matching in tadpoles • MHC, kinship, and templates • Rule-of-thumb models of kin recognition

48. Kin recognition in penguins. Kin recognition via vocal signatures has been examined in (A) the emperor penguin and (B) the king penguin. Both species of penguins live in large colonies, and parents returning from foraging with food for their chick use vocal cues to find their offspring in the midst of numerous other chicks.

49. Matching models • Internal template • Kin recognition matching models • Individual 1 determines if individual 2 is kin or nonkin, depending on how closely individual 2 matches the internal template of individual 1. • 案例：Template matching in tadpoles • Kin recognition in spadefoot toads

50. As in the spadefoot toad, two different tadpole morphs – a carnivorous cannibal and an herbivorous omnivore– exist in a number of amphibian species. Here a tiger salamander cannibal morph (right) is eating an omnivore morph (left).