Parental Care and Mating Systems

1. ?????????(Parental Care and Mating Systems)-????? (Ethology) ???(Ayo) ?? ???? ??????? ????????? ??

2. Ayo ?? (????? 2010) 2

3. Ayo ?? (????? 2010) 3 14 ?????????(Parental Care and Mating Systems) Parental care Conflicts (??) among family members Some factors that influence the allocation of parental resources Overall patterns of parental care Dispensing with(??) parental care– brood parasitism Mating systems Classifying mating systems Monogamy (???) Polygyny (???) Polyandry (???)

4. Ayo ?? (????? 2010) 4 Reproduction is a complicated affair In several species of mammals, including humans, mothers that produce sons incur greater costs than those that produce daughters Higher parasite loads A delay in the next reproductive effort Reduced likelihood of future reproduction Reduced longevity

5. Ayo ?? (????? 2010) 5 Sons are expensive Mothers who produce sons experience reproductive costs Making them less able to invest in their next child Human offspring born after elder brothers had similar survival But lower lifetime reproductive success than offspring born after elder sisters due to Lower lifetime fecundity (number of offspring produced)

6. Ayo ?? (????? 2010) 6 In a preindustrial human population in Finland, producing sons does not affect the survival of subsequent offspring but does affect the lifetime reproductive success of subsequent offspring. (a) the probability of surviving to 15 years of age in relation to the sex of elder offspring. (b) Lifetime reproductive success, defined as number of children raised to 15 years of age, in relation to the sex of the elder offspring.

7. Ayo ?? (????? 2010) 7 Parental care Parental investment: investment by parents in an offspring That increases the survival of that offspring But decreases the ability of investment in other offspring Direct parental behaviors Have an immediate impact on offspring and their survival Nursing, feeding, grooming, transporting, huddling with young Indirect parental behaviors Are performed while away from the young Do not involve direct physical contact with offspring Still affect offspring survival, but not immediately

8. Ayo ?? (????? 2010) 8 Indirect parental care in mammals Includes acquiring and defending critical resources Building and maintaining nests or dens Defending offspring against predators or infanticidal conspecifics Caring for pregnant or lactating females is included Pregnancy and lactation are energetically demanding Delivering food to females is very helpful Male owl monkeys feed lactating females (?????) Increases the quantity and/or quality of milk produced Which reduces the interval between births of offspring Parents benefit by producing more, well-fed offspring

9. Ayo ?? (????? 2010) 9 Parental investment maximizes reproductive success An individual’s lifetime reproductive success is maximized Not necessarily each reproductive event Parents must make two decisions How much of their resources to devote to reproduction instead of to their own growth and survival How to allocate available resources among their offspring These decisions can lead to conflicts of interest Between parents and offspring And among siblings

10. Ayo ?? (????? 2010) 10 Conflicts over parental investment: sexual conflict Sexual conflict: conflict between the evolutionary interests of males and females Particularly mating and parental investment Involves interactions between males and females during which Each individual’s fitness depends on its own strategy As well as the strategy of its partner Conflict in parental investment emerges because the costs of providing care are paid separately by each parent Both parents benefit, regardless which one provides the care Each parent prefers that the other do most the work

11. Ayo ?? (????? 2010) 11 Conflicts over parental investment: intra/interbrood conflicts Intrabrood conflict: young try to obtain resources That the parents prefer to distribute to other members of the current brood Interbrood conflict: young try to obtain resources that parents prefer to save for future offspring Differences in the distribution of resources by parents can lead to sibling rivalry (??) Each youngster derives a greater fitness benefit from the parental care it receives than from the care its siblings receive

12. Ayo ?? (????? 2010) 12 Sibling rivalry(??) Involves overt, substantial aggression Can result in siblicide: the death of one or more siblings In other species, rivalry is subtler Lower levels of fighting Scramble competition: siblings race to outcompete each other for parental resources, with lower levels of fighting

13. Ayo ?? (????? 2010) 13 Sibling competition in domestic piglets Begins before birth The uterus is too small to support maximum growth of embryos Some embryos die Others survive but have low birth weight Are at a severe disadvantage for the intense postnatal competition Piglets(??) compete for teats Large piglets locate and retain possession of a teat Smaller piglets are displaced and starve

14. Ayo ?? (????? 2010) 14 Piglet battles Battles involve frantic shoving and wounding Newborns have slashing canine(??) and incisor(??) teeth That function solely in early sibling competition

15. Ayo ?? (????? 2010) 15 Siblicide Sibling rivalry leads to one offspring attacking and killing its brother or sister Common in species where resources are limited And parents deposit eggs or young in a “nursery” with limited space Nursery = a uterus, brood pouch, parent’s back, nest, or den It may be advantageous to save the parents time and energy By eliminating the young least likely to reach adulthood

16. Ayo ?? (????? 2010) 16 Factors influencing allocation of parental resources: life history Expected life span influences a parent’s allocation of resources To maximize lifetime reproductive success Whether parents have future opportunities to breed Is affected by the parent’s age and the life span In short-lived species with little hope of producing more young Parents invest more heavily in the present young Parents of long-lived species spend more of their resources on their continued growth and survival Because they might have the opportunity to breed again

17. Ayo ?? (????? 2010) 17 Parental care in Leach’s storm-petrel (??????) Storm petrels are long-lived seabirds Adults visit food patches to feed their chicks Foraging trips last two to three days so the cost of flight is significant

18. Ayo ?? (????? 2010) 18 Parental care in starlings (??) and tits (??) When reproductive costs of short-lived starlings and tits were increased They bore part of the increased costs themselves They allocated the same amount of resources to their chicks In short-lived species Each clutch represents a large part of the parent’s lifetime reproductive success

19. Ayo ?? (????? 2010) 19 Factors influencing allocation of parental resources: certainty of paternity Parental solicitude(??) toward young is correlated with the likelihood of genetic relatedness Females are certain that they are related to their offspring 50% of a mother’s genes are present in each of her progeny A male cannot be so confident He has no guarantee that his sperm fertilizes her eggs He risk investing time and energy in raising another male’s offspring, resulting in Decreased chances of evolution of paternal behavior

20. Ayo ?? (????? 2010) 20 Certainty of paternity influences parental care in sunfish Male bluegill sunfish (?????) decrease parental care when they are less certain of their paternity Parental males compete for nest sites, guard females and care for young Sneaker males steal fertilizations and do not provide parental care Parental males had chemical cues from fry(??) to reassess(??) their paternity

21. Ayo ?? (????? 2010) 21 Certainty of paternity influences level of parental care by male bluegill sunfish. (a) In experiment (treatment group) display less parental care toward eggs than males not exposed to sneaker males (control group). (b) males whose clutches had been manipulated (1/3 eggs been exchanged).

22. Ayo ?? (????? 2010) 22 Factors influencing allocation of parental resources: gender of offspring Parental investment is influenced by gender of the offspring Sex allocation: the manner in which parents distribute resources between sons and daughters Parents can bias their allocation in two ways They can produce more offspring of one sex They can provide more (or better) resources to offspring of one sex Most animals divide resources equally between sons and daughters Others (i.e. brown songlarks) distribute resources unevenly

23. Ayo ?? (????? 2010) 23 Songlarks distribute resources unequally Polygynous warblers: one male mates with more than one female Extreme sexual size dimorphism: males are twice as heavy Mothers feed the young At birth, nestling males and females do not differ in body mass But males become much heavier Male nestlings receive more, higher quality prey

24. Ayo ?? (????? 2010) 24 Songlark mothers bias their parental investment toward their sons. (1) although male and female nestlings have similar body masses at hatching, males become increasingly larger than females in the nest few weeks. (b) mother not only deliver prey at higher rates to broods with more males, they feed male nestlings a high quality diet than they feed female nestlings.

25. Ayo ?? (????? 2010) 25 The benefit of raising large male offspring Raising male offspring is costly to the mother Large body size is an important determinant of male reproductive success Less important for female reproductive success By producing large sons that will successfully attract and compete for mates Mothers ensure that their genes are well-represented in future generations

26. Ayo ?? (????? 2010) 26 Patterns of parental care Differences exist among taxa in the extent and pattern of parental care Within vertebrates: most teleost fishes, frogs, toads, lizards, and snakes show no parental care at all All crocodilians and mammals display some form of parental care Also typical of most birds A few species lay their eggs in the nests of others And relinquish all care to the “host” parents

27. Ayo ?? (????? 2010) 27 Female-only care The most common form of care in mammals Internal gestation and lactation necessitate a major parental role for the female Early paternal care is always in conjunction with maternal care Restricts the ability of the male to help Male mammals seek mating opportunities elsewhere

28. Ayo ?? (????? 2010) 28 Biparental care The most common form of care in birds Birds develop outside the mother’s body Male birds are as capable as their mates at providing care Incubation, feeding, and guarding are divided equally Two parents are better than one

29. Ayo ?? (????? 2010) 29 Male care in fishes and amphibians Can be male-only care or with female care (biparental care) In fishes and amphibians: usually a form of solitary male care These animals rarely feed their offspring Parental duties consist of guarding Performed as well by one parent as by two

30. Ayo ?? (????? 2010) 30 Biparental care in fishes and amphibians Biparental care in fish: for survival and growth of offspring Evolved in ciclids (????????) because their broods face intense predation pressure

31. Ayo ?? (????? 2010) 31 Mode of fertilization affects patterns of parental care Reflect basic biological differences: where the young develop and how they are fed Reflect ecological conditions (i.e. intensity of predation) Teleost fishes, frogs and toads display four categories of parental care in vertebrates: No care Male-only care Female-only care Biparental care

32. Ayo ?? (????? 2010) 32 Patterns of parental care exhibited by some groups of vertebrates.

33. Ayo ?? (????? 2010) 33 Diagram showing the major independent evolutionary transitions among modes of parental care in ray-finned fishes (????) .

34. Ayo ?? (????? 2010) 34 Fertilization and parental care The association between mode of fertilization and mode of parental care relates to the proximity of adults and offspring External fertilization in a territory defended by a male Is associated with male parental care With internal fertilization The female carries the embryos And is in the best position to care for the young

35. Ayo ?? (????? 2010) 35 Sex rolesGreater female investment in parental care In many animals, females provide more parental investment than males Thought to explain sex differences in mating competition The sex with greater parental investment (females) becomes a limiting resource, and An object of competition among individuals of the sex investing less (males) Because of greater female investment, females select mates Males compete for access to females This favors large body size and aggressiveness

36. Ayo ?? (????? 2010) 36 Sex role reversal The burden of parental care falls on the male When parental investment by males is greater Males are choosy Females are competitive Sex role reversal occurs in insects, birds, crustaceans, fishes, amphibians Overall, sex role reversed species are in the minority

37. Ayo ?? (????? 2010) 37 Sex role reversal in northern jacanas A polyandrous mating system: a female pairs with several males Females defend a territory overlapping several male territories She plays a dominant role in courtship Females are much larger than males Females back up males in confronting potential predators She’s more effective than the male at predator deterrence

38. Ayo ?? (????? 2010) 38 African jacana Males: build nests, incubate eggs, and care for and defend chicks.

39. Ayo ?? (????? 2010) 39 Brood parasitism Intraspecific brood parasites: lay eggs in conspecific’s nests Cliff swallows, red-fronted coots (??) , wood ducks She may or may not lay eggs in her own nest Interspecific (obligate) brood parasites: lay their eggs in other species’ nests They have no other reproductive option They never build nests Honeyguides(???), Old World cuckoos(??), New World cuckoos, viduine finches, cowbirds, black-headed ducks

40. Ayo ?? (????? 2010) 40 black-headed ducks

41. Ayo ?? (????? 2010) 41 Cowbird

42. Ayo ?? (????? 2010) 42 Raising young brood parasites Host parents experience reduced reproductive success Damage is directly inflicted by a parasitic adult or its offspring A female cuckoo may eat or throw out the host’s egg Or kill the young of the host Nestling cuckoos (??) evict (??) eggs or young from the nest of their foster parents Nestling honeyguides(???) kill young with whom they share the nest

43. Ayo ?? (????? 2010) 43 Brood parasites monopolize parental care They mature more rapidly than a host’s young Their huge mouths and persistent begging elicit preferential feeding The host’s young may die from starvation, crowding, or trampling Parasitic young may benefit by keeping a few of the host’s young around Host parents increase the rate at which they feed larger broods Host parents may desert single chick broods

44. Ayo ?? (????? 2010) 44 Host species try to avoid being parasitized Host species conceal and defend their nests Identify and remove the eggs (or young) of parasites Brood parasites try to deceive hosts Cuckoos lay eggs in the late afternoon when hosts are less attentive Parasitic eggs or young resemble those of the host species

45. Ayo ?? (????? 2010) 45 Waxbills (???)

46. Ayo ?? (????? 2010) 46 Mating Systems The ultimate goal of reproduction for both sexes is to maximize fitness (the relative number of offspring that survive and reproduce) The reproductive success of males and females is constrained by different factors A male’s success is limited by access to females While a female’s is limited by access to resources

47. Ayo ?? (????? 2010) 47 Increasing reproductive success A male can boost his reproductive success by mating with several females A female increases her reproductive success by gathering more resources Including male parental care and access to a high-quality territory Males focus on mating effort Females emphasize parental effort Each parent tries to maximize its own reproductive success Even if this is costly to the other

48. Ayo ?? (????? 2010) 48 Classifying mating systems Mating systems are defined based on the number of copulatory partners per individual per breeding season Monogamy: a male and female have only a single mating partner per breeding season Polygyny: males copulate with more than one female Polyandry: females mate with more than one male Polygynandry (promiscuity): both males and females mate with multiple individuals

49. Ayo ?? (????? 2010) 49 Ecological factors influence mating systems Predation, resource quality and distribution, and availability of receptive mates affect the need for Parental care The ability of males to monopolize females The ability of females to choose among potential suitors Ecological conditions vary Flexibility is associated with a species’ mating patterns Black howler monkeys polygynous in a deciduous habitat polygynandrous in a riparian (riverside) habitat Monopolizing females by a single male is less likely in the lush riparian habitat

50. Ayo ?? (????? 2010) 50 Black howler monkeys

51. Ayo ?? (????? 2010) 51 Sexual fidelity(???) is hard to find in any system Social monogamy exclusive living arrangement with one male and one female No assumptions about mating exclusivity or biparental care Genetic monogamy: an exclusive mating relationship between one male and one female Very few species are genetically monogamous Some socially monogamous fishes and mammals engage in extrapair fertilizations Cuckoldry is a problem for polygynous males Extra-pair matings are the rule rather than the exception

52. Ayo ?? (????? 2010) 52 Male extra-pair matings A male’s costs: the time and energy in searching for receptive females other than his mate While he’s away, his primary mate may copulate with another male Reducing his reproductive success A male’s benefits: if he successfully inseminates mates of other males He can boost his reproductive success

53. Ayo ?? (????? 2010) 53 Female extra-pair matings Material benefits: A female gets help raising her offspring Extra-pair males defend the nest from predators Females exchange copulations for a valuable resource, i.e. food Sufficient sperm may be provided to fertilize all her eggs Genetic benefits: to obtain “good genes” for their offspring Post-fledgling survivorship of the young is related to the genetic father Females of cooperatively breeding bird species avoid mating with close relatives

54. Ayo ?? (????? 2010) 54 Extra-pair matings in grey-crowned babblers They live in social groups of a dominant breeding pair and nonbreeding helpers Members of the dominant pair may be related Extrapair young are found in the nest

55. Ayo ?? (????? 2010) 55 Monogamy Monogamy: male and female have only a single mating partner per breeding season Sperm from one male is sufficient to fertilize a female’s eggs Monogamy is sufficient from the female perspective For males, confining copulation to a single female ensures genetic representation in the next generation What ecological circumstances favor monogamy over polygyny? Necessary biparental care Distribution of females Mate guarding

56. Ayo ?? (????? 2010) 56 Monogamy and biparental care When it is necessary or important for offspring survival Monogamy may be favored Biparental care is more common among birds It’s rare in mammals Males of some species have parental responsibilities And the fitness of both mates depends on the male’s parental investment

57. Ayo ?? (????? 2010) 57 Male California mice care for their young Fathers participate in all parental activities to the same extent as mothers Once paired, these mice never stray(??) Pups are born at the coldest time of the year and need their parents’ body heat to survive Both parents take turns huddling over the pups Removal of fathers resulted in lower pup survival

58. Ayo ?? (????? 2010) 58 Male parental care in rodents

59. Ayo ?? (????? 2010) 59 Monogamy and distribution of females Distribution of females throughout the habitat influences mating systems If it is hard for a male to monopolize multiple mates Circumstances will favor monogamy over polygyny When receptive females are uniformly distributed i.e. because they defend exclusive territories Monogamy may evolve If females are widely dispersed It is beneficial for a male to remain with a given female The male is at least assured of access to one mate

60. Ayo ?? (????? 2010) 60 Symbiotic shrimp are monogamous They live inside the mantle cavity of the pearl oyster Pearl oysters are small and scarce Shrimp pairs consisted of a male and a female

61. Ayo ?? (????? 2010) 61 Monogamy and mate guarding Monogamy may evolve if a male can guard only one female Kirk’s dik-dik (????) form permanent monogamous bonds Dik-diks seem to be faithful to their mates Genetic analyses revealed no evidence of extra-pair paternity Why has such devotion has evolved in dik-diks? Paternal care is absent—the male does not defend resources, reduce predation risk, or commit infanticide Some monogamous males defend territories that could support more than one female Females have ample opportunity to wander away

62. Ayo ?? (????? 2010) 62 ????(??Madoqua kirkii) Kirk’s dik-dik (????),????????,?????,???????,????????????

63. Ayo ?? (????? 2010) 63 Monogamy in dik-diks Males prevent other males from knowing when she is in estrus He covers up the scent of his female’s dung by scratching dirt and then defecating on top of it He marks his territorial borders with from glands under his eyes If a male tried to overmark the scent of two females He might fail to mark his territory sufficiently And lose ownership of the territory The female accepts being guarded An extra-pair mating might cause a fight between her male and the rival that could harm her or her offspring

64. Ayo ?? (????? 2010) 64 Polygyny: costs and benefits for males Polygyny: one male mates with more than one female during a breeding season A male benefits by producing more offspring If paternal care is not required Males maximize reproductive output through multiple matings Costs to a male: An increased chance of cuckoldry since he does not guard each female Costs associated with achieving dominance or defending resources or territories

65. Ayo ?? (????? 2010) 65 Polygyny: costs for females Males do not help rear the young If males do provide some parental care, it is divided among offspring Or sometimes care is provided only to the first female They must also share essential resources (nest sites or territories) Activity around these areas may attract predators Other females may increase competition for resources

66. Ayo ?? (????? 2010) 66 Benefits for females: the polygyny threshold hypothesis Polygyny threshold hypothesis: females gain advantages when the benefits achieved by mating with a high-quality male And gaining access to his resources Compensate for the costs A female may reproduce more successfully as a secondary mate on a high-quality territory Than as a monogamous mate on a low-quality territory Polygyny threshold: the difference in a territory’s quality that make secondary status a better reproductive option for females Females join a harem when they have greater reproductive success than monogamous alternatives

67. Ayo ?? (????? 2010) 67 The polygyny threshold The reproductive success of females decrease as the harem’s size increases Female red-winged blackbirds prefer unmated males to already mated males But this is reversed if the territories of mated males are superior to those of unmated males

68. Ayo ?? (????? 2010) 68 Benefits for females: the sexy son hypothesis Access to good genes for her offspring compensates a female for the costs of polygyny A female may benefit if her sons inherit the genes that made that male attractive Her sexy sons provide her with many grandchildren A female that chooses an already-mated male benefits indirectly If the good genes she acquires for her offspring boost their survival and reproductive success

69. Ayo ?? (????? 2010) 69 Types of polygyny: female defense polygyny Female defense polygyny: a male defends a harem of females Females live in groups that a male can easily defend Female gregariousness(??) is related to Cooperative hunting Increased predator detection Reproduction Female elephant seals form dense aggregations Female gregariousness Shortage of suitable birth sites They return annually to traditional locations

70. Ayo ?? (????? 2010) 70 Female defense polygyny in elephant seals A single dominant male can monopolize access to 40 or more females This male defends his harem Against all other male intruders in bloody, and sometimes lethal, fighting

71. Ayo ?? (????? 2010) 71 Types of polygyny: resource defense polygyny Males defend resources essential to female reproduction (e.g., nest sites or food) Rather than defending females A male can monopolize a number of mates by controlling critical resources Typical conditions include: Quality of the monopolized resource reflects male quality Females prefer males with resources over those without Males with resources have higher mating and reproductive success

72. Ayo ?? (????? 2010) 72 Females choose quality resources A female’s choice is based on the quality of resources controlled by a male Scorpionfly males fiercely defend the area around a dead arthropod The female must copulate to gain access to this food Larger males obtain larger arthropods Small males, unable to obtain arthropods, steal copulations or present salivary secretions (a nuptial gift)

73. Ayo ?? (????? 2010) 73 Scorpionfly (??) Panorpa communis

74. Ayo ?? (????? 2010) 74 Types of polygyny: lek polygyny Males defend “symbolic” territories Located at traditional display sites called leks Males do not provide parental care They defend only their small territory on the lek Not groups of females or resources

75. Ayo ?? (????? 2010) 75 Two black grouse (???) males displaying on a lek.

76. Ayo ?? (????? 2010) 76 Females visit a lek to select a mate Occurs when environmental factors make it difficult for males to monopolize females directly (female defense polygyny) Or indirectly (resource defense polygyny) Male sandflies gather on the back of a vertebrate host and defend small territories Females visit these nocturnal leks and evaluate several males But copulate with just one Some males copulate with many females Others will be unsuccessful at finding a mate

77. Ayo ?? (????? 2010) 77 Sandfly

78. Ayo ?? (????? 2010) 78 Evolution of lek behavior: the male’s perspective Males may require specific display habitats That are limited and patchily distributed Leks may provide protection from predators Through increased vigilance Leks are information centers Males exchange news on good foraging sites

79. Ayo ?? (????? 2010) 79 Hot spot vs. hot shot Males gather near “hot spots” where females are most likely to be encountered Less successful males have better mating chances near highly successful males (“hotshots”) Less successful males near hotshots obtain more copulations

80. Ayo ?? (????? 2010) 80 Evolution of lek behavior: the female’s perspective Large groups of males may make mate choice easier To distinguish between superior and inferior males It may reduce the vulnerability of females to predation A predator might be distracted by so many displaying individuals Lek mating may reduce competition between the sexes for resources

81. Ayo ?? (????? 2010) 81 Polyandry Polyandry: a female has more than one mate during the breeding season Female reproductive success can increase with more mates If copulation includes critical resources or male parental assistance Polyandrous insects increase the number of eggs laid (clutch effect) and their hatching success Reduced risk of fertilization by genetically incompatible sperm

82. Ayo ?? (????? 2010) 82 Clutch effects and hatching success Clutch effects are due to: Increased nutrients passed to females Increased receipt by females of hormonal stimulants in male ejaculates Hatching success effects include: Avoidance of sperm depletion Increased genetic diversity among progeny Reduced risk of fertilization by genetically incompatible sperm

83. Ayo ?? (????? 2010) 83 Honey bees are polyandrous The queen mates with multiple males Increases genetic diversity Drones: reproductive males Workers: infertile females Closely related to the queen Diverse colonies: More efficient at building combs Weigh more Survive winter Forage at higher rates Produce more workers and drones

84. Ayo ?? (????? 2010) 84 Summary Evolutionary decisions must be made about The amount of care and who assumes parental duties Evolutionary conflicts over parental investment include Sexual conflict, intrabrood conflict, interbrood conflict Avian brood parasites give up parental responsibilities Conflicts of interest characterize social behavior Males produce more offspring by seeking additional mates Females emphasize parental effort and produce more offspring by gaining male parental investment Mating systems are affected by ecological factors (predation, resource quality and distribution) and availability of mates

85. Ayo ?? (????? 2010) 85 Summary Monogamy: a male and female have a single partner per breeding season Polygyny: males copulate with more than one female Polyandry: females mate with multiple males during the breeding season Polygynandry: both males and females mate multiple times Extra-pair matings are common Benefits to males: increased number of offspring Females gain help in raising offspring, obtaining food, genetic benefits, fertility insurance, high-quality genes

86. Ayo ?? (????? 2010) 86 ?????