Transcript Document
Conflict and Cooperation
Lecture 7
Lecture Outline 1.
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Evolutionary game theory Sexual selection Kin selection and the evolution of cooperation Selfish genes
John Nash William Hamilton John Maynard Smith
Evolutionary Game Theory
Evolutionarily Stable Strategy (ESS) is a strategy which, if adopted by a population of players, cannot be invaded by any alternative strategy that is initially rare Payoff Matrix H D H w(H,H) w(H,D) D w(D,H) w(D,D) • Interactions between 2 individuals, each of which has 1 of 2 or more phenotypes (strategies) {H,D} • For each possible pairwise combination of strategies, an individual has a different payoff w(H,D) • The payoff depends not only on the individual’s own phenotype, but also on that of the individual it interacts with w(H,H)≠w(H,D)
Evolutionary Game Theory
The fitness of phenotypes H and D are: w(H) = p w(H,H) + (1-p) w(H,D) w(D) = p w(D,H) + (1-p) w(D,D) where p is the frequency of H in the population H is an ESS if: w(H)>w(D) If D is a rare mutant (p≈1) this condition implies that: either (a) w(H,H)>w(D,H) or (b) w(H,H)=w(D,H) and w(H,D)>w(D,D)
Evolutionary Game Theory
Hawk-Dove Game One of the earliest problems to which evolutionary game theory was applied was conflict between males competing for resources Hawk: H Dove: D H ½ (V C) 0 D V ½ V Hawk Dove Escalate a conflict until it is injured (with cost C) or until it gains the contested resource (with gain V) Retreats when threatened neither gaining nor loosing fitness When 2 phenotypes of the same kind coincide they have equal chances of wining or losing
Evolutionary Game Theory
Hawk-Dove Game Hawk: H Dove: D H ½ (V C) 0 D V ½ V
Pure Strategies
Play always the same strategy • If V>C it pays to be a Hawk • If V Is Hawk an ESS? Hawk-Dove Game Hawk: H Dove: D H ½ (V C) 0 D V ½ V Mixed Strategies Play sometimes one strategy and sometimes the other Is there a mixed ESS? A mixed strategy p* requires that w(H)=w(D) p* ½(V-C)+(1–p*) V= p* 0+(1–p*) ½V and p*=V/C (playing Hawk with probability V/C) is a mixed ESS The optimal behavior is variable and contingent on the values V and C Hawk-Dove-Assessor Game Hawk: H Dove: D Assessor: A H ½(V-C) 0 ½V Payoff Matrix D V ½V ¾ V A ½(V-C) ¼ V ½V Assessor Strategy Display first and escalate the conflict only if it judges the opponent to be smaller or weaker. If larger plays Hawk and wins if smaller play Dove avoiding the cost • Assumptions: The probability of being larger is • 50% Assessment is costless and accurate Hawk-Dove-Assessor Game Hawk: H Dove: D Assessor: A H ½(V-C) 0 ½V D V ½V ¾ V A ½(V-C) ¼ V ½V Pure Strategies Is Hawk an ESS? Is Assessor an ESS? Many animals react aggressively or not depending on their opponents size or correlated features Hawk-Dove-Assessor Game Many animals react aggressively or not depending on their opponents size or correlated features Male toads that clasps females before the eggs are laid and fertilized are often aggressively displaced by larger males but not by smaller ones. A male is unlikely to try to displace a mounted male that is larger than himself Hawk-Dove-Assessor Game Hawk-Dove-Assessor Game 14/50 approaches result into fight Hawk-Dove-Assessor Game Honest signals of the of the individual’s fighting ability or resource-holding potential Deceptive signals indicating greater fighting ability than the individual actually has Deceptive signals should be unstable in evolutionary time because selection would favor genotypes that ignored the signals, which having lost their utility would be lost in subsequent evolution Dishonest signals however are not uncommon Male fiddle crab Uca annulipes Concept Describes differences among individuals of a sex in the number of reproductive capacity of mates they obtain Concept Sexual selection exists because females produce relatively few large gametes (eggs) and males produce many small gametes (sperm) This difference creates an automatic conflict between the reproductive strategies of the sexes: • A male can mate with many females and he often suffers little reduction in fitness if he should mate with an inappropriate female • A female can be fertilized by a single male and her fitness can be significantly lowered by inappropriate mating Concept The operational sex-ratio (relative number of males and females in the mating pool) is often male-biased because males mate more frequently Females are a limiting resource for males but males are not Variation in mating success is generally greater among males than females and is a measurement of the intensity of sexual selection Phalaropes: Sex-Role Reversal Phalaropus fulicarius Contests Between Males and Between Sperm Contest among males for mating opportunities Antlers of red deer Cervus elaphus Canine teeth of the babirusa Babyrousa babyrussa Directional selection for greater size, weaponry or display features can cause an arms race Such escalation becomes limited by opposing ecological selection if the cost of larger size or weaponry becomes sufficiently great Contests Between Males and Between Sperm Males reduce the likelihood that other males’ sperm will fertilize a female’s eggs Lateral Horn In many damselflies, the male’s genitalia are adapted to remove the sperm of previous mates from the female’s reproductive tract Spinelike hairs and clump of rival’s sperm Sperm competition Occurs when the sperm of two or more males have the opportunity to fertilize a female’s eggs Penis of the black-winged damselfly Calopteryx Sexual Selection by mate choice Sexual Selection by mate choice Individuals of one sex (usually male) compete to be chosen by the other Females mate preferentially with males that have larger, more intense, or more exaggerated characters The preferred male characters are often ecologically disadvantageous Tungara Frogs Physalaemus pustulosus Frog-eating Bats Trachops cirrhosus Female choosiness may likewise have costs: the time spent searching for acceptable males has been shown to reduce reproductive output in several species Sexual Selection by Mate Choice Why should females have a preference for these traits, especially for features that seem arbitrary and dangerous the males bearing them? 1. Sensory bias 2. 3. Direct benefit to choosy females Indirect benefit to choosy females a. Runaway sexual selection b. Indicators of gene quality 4. Antagonistic coevolution Sexual Selection by mate choice Sensory Bias Certain traits may be intrinsically stimulating and evoke a greater response simply because of the organization of the receptor’s sensory system In some species of the fish genus Xiphophorus part of the male tail is elongated into a “sword” Females preferred males with swords not only in Xiphophorus but also in the swordless genus Priapella Sexual Selection by mate choice Direct Benefit to Choosy Females Male provides a direct benefit to the female or her offspring: nutrition, superior territory, parental care There is selection pressure on females to recognize males that are superior providers The preference selects for males with the distinctive correlated character Sexual Selection by mate choice Indirect Benefits of Mate Choice Male provides no direct benefit to either the female or her offspring but contributes only his genes Alleles affecting female mate choice increase or decrease in frequency depending on the fitness of the females’ offspring. Thus females may benefit indirectly from their choice of mates Sexual Selection by mate choice R UNAWAY S EXUAL S ELECTION M ODEL (S EXY S ON H YPOTHESIS ) The evolution of male trait and a female preference, once initiated, becomes a self-reinforcing or runaway process Consider haploid males of genotypes T 1 and T 2 (fr t 2 ) (fr t 1 ) T 2 has an exaggerated trait (longer tail) that carries an ecological disadvantage (increasing the risk of predation) Females of genotype P 2 type P 2 , whereas P 1 (fr p 2 ) prefer males of females exhibit little preference It is assumed that P 1 neutral and P 2 are selectively Sexual Selection by mate choice Although the expression of genes P and T is sex limited both sexes carry both genes and transmit them to offspring Because P 2 females and T 2 males tend to mate with each other linkage disequilibrium will develop Any increase in the frequency of the male trait is accompanied by an increase in the frequency of the female preference through hitchhiking Sexual Selection by mate choice Because of the genetic correlation between loci, an increase in t 2 is accompanied by an increase in p 2 : T 2 males have more progeny and their daughters tend to inherit the P 2 allele, so P 2 also increases in frequency As P 2 increases males have a still greater mating advantage because they are preferred by more females Many exaggerated sexually selected traits carry ecological costs for the males that bear them. Female choice may also carry an ecological cost (ex delayed reproduction) Such costs may prevent the runaway process from occurring, or they mat lead to an equilibrium at which the male trait and the female preference are less extreme than if there were no cost Runaway sexual selection of this kind could explain the extraordinary variety of male ornaments among different species of hummingbirds any many other animals Sexual Selection by mate choice G OOD G ENES M ODEL (H ANDICAP H YPOTHESIS ) Because females risk substantial losses of fitness if their offspring do not survive or reproduce, one could argue that females should evolve to choose males with high genetic quality, so that their offspring will inherit “good genes” and so have a superior prospect of survival and reproduction Stickelback Fish Any male trait that is correlated with genetic quality (an indicator of good genes) could be used by females as a guide to advantageous matings, so selection would favor a genetic propensity in females to choose mates on this basis Sexual Selection by mate choice Antagonistic Coevolution Genes that govern male versus female characters may conflict resulting in antagonistic coevolution Such evolution may consist of a protracted “arms race” in which change in male character is parried or neutralized by evolution of female character, which in turn selects for change in the male character and so on in a chain reaction Abalone Haliotis sorenseni Abalones are externally fertilizing species. Sperm compete to fertilize eggs so selection on sperm always favors a greater ability to penetrate eggs rapidly Selection on eggs should favor features that slow sperm entry or else polyspermy may result (polyspermy disrupts development) Coevolution might be the cause of the extraordinarily rapid evolution of the amino acid sequence of the sperm lysin protein of abalones, a protein released by sperm that bores a hole through the vitelline envelope surrounding the egg Sexual Selection by mate choice Chase-away Sexual Selection Females evolve resistance to male’s inducements to mate and their resistance selects for features that enable males to overcome the females’ reluctance Semen Toxicity Forced Copulation Ex Water Striders females to copulate Males force Traumatic Insemination Ex Bed Bug Males pierce his mate’s abdominal wall with his genital structure Water Strider Gerris sp Explaining how altruism –which by definition reduces personal fitness– can arise by natural selection is a major problem, and the central theoretical problem of sociobiology Darwin’s theory of natural selection is based on individual advantage. Cooperative interactions seem antithetical to evolution by natural selection and require explanation Until 1960’s it was common for biologists to assume that cooperation had evolved because it benefited the population or species (group selection). The modern study of cooperation focus on individual selection. Prisoner's Dilemma Confess: C Silent: S 4 C 3 S 1 2 Prisoner's Dilemma The Prisoner's Dilemma game takes its name from the following scenario: You and a criminal associate have been busted. Fortunately for you, most of the evidence was shredded, so you are facing only a year in prison. But the prosecutor wants to nail someone, so he offers you a deal: if you squeal on your associate –which will result in his getting a five year stretch– the prosecutor will see that you are set free. Which sounds good, until you learn your associate is being offered the same deal – which would get you five years To cooperate, or not cooperate? This simple question, expressed in an extremely simple game, is a crucial issue across a broad range of life • Why shouldn't a barracuda eat the little fish that has just cleaned it of parasites • Fig wasps collectively limit the eggs they lay in fig trees. But why shouldn't any one fig wasp cheat and leave a few more eggs than her rivals? • At the level of human society, why shouldn't each of the villagers that share a common but finite resource try to exploit it more than the others? Yet barracudas, fig wasps, and villagers all cooperate. It has been a constant problem in evolutionary studies to explain how such cooperation should evolve, let alone persist, in a world of self-maximizing egoists Explaining how altruism –which by definition reduces personal fitness– can arise by natural selection is a major problem, and the central theoretical problem of sociobiology Theories of cooperation and altruism Cooperation Direct Benefits Indirect Benefits Enforced Non Enforced Green -beard Punishment Reward Reciprocity Kin Selection Limited Dispersal Kin Discrimination Direct Indirect D IRECT B ENEFITS : N ON ENFORCED Cooperative behavior often evolves simply because it is advantageous to the individual Ex Joining flock or herd Ex Unrelated helpers and delayed benefit Pied kingfisher Ceryle rudis D IRECT B ENEFITS : E NFORCED : M ANIPULATION & P UNISHMENT A donor may dispense aid to a recipient not because it is adaptive but simply because the donor is being manipulated or coerced Ex Cuckoo Common Cuckoo Cuculus canorus D IRECT B ENEFITS : E NFORCED : R ECIPROCITY It can be advantageous for an individual to help another if the recipient provides reciprocal aid in the future Vampire Bats Desmodus rotundus I NDIRECT B ENEFITS : G REEN BEARD G ENES Facultative harming greenbeards include the Gp-9 gene of the red fire ant Solenopsis invicta , which makes carrying workers execute non-carrying queens I NDIRECT B ENEFITS : K IN S ELECTION Kin selection Selection based on the effect of an allele on both the fitness of the individual bearing it and the fitness of other individuals that carry copies of the same allele For kin selection to operate individuals must dispense benefits more often to kin than non-kin. This can happen in two ways: • Many animals can distinguish kin from non-kin • The population may be structured so that interacting individuals are more likely to be related than unrelated Inclusive Fitness and Kin Selection Inclusive Fitness Is the effect of an allele on both the fitness of the individual bearing it (DIRECT FITNESS) and the fitness of other individuals that carry copies of the same allele (INDIRECT FITNESS) Inclusive Fitness and Kin Selection Kin selection Selection based on inclusive fitness Hamilton’s Rule An altruistic trait can increase in frequency if the benefit ( B ) received by the donor’s relatives weighted by their relatedness ( r ) to the donor, exceeds the cost ( C ) of this trait to the donor’s fitness: rB > C Coefficient of Relatedness Is the fraction of the donor’s genes that are identical by descent with any of the recipient’s genes Mother/Offspring Sibling/Full Sibling r = ½ r = ½ INDIRECT BENEFITS: KIN SELECTION: KIN DISCRIMINATION AND CANNIBALISM Many species of animals are cannibalistic preying on smaller individuals of the same species. Many such species discriminate kin from non-kin and are less likely to eat related individuals Tadpoles develop into: • Detritus and plant omnivores Associate more with their siblings • Cannibalistic carnivores Associate more with non relatives Carnivores eat siblings much less frequently than unrelated individuals Spadefoot Toad Scaphiopus bombifrons INDIRECT BENEFITS: KIN SELECTION: COOPERATIVE BREEDING In many species of animals, young are reared not only by their parents, but also by other individuals that are physiologically able to reproduce but do not. Several factors may explain cooperative breeding, including kin selection, since in many species, the helpers aid their parents in rearing their children Primary are related Secondary are unrelated Pied kingfisher Ceryle rudis Meerkats S OCIAL I NSECTS Eusocial animals Animals in which nearly or completely sterile individuals (workers) rear the offspring of reproductive individuals , usually their parents Known in Naked mole rat, termites, many hymenoptera Naked Mole Rat Heterocephalus glaber Eusocial hymenoptera are haplodiploid: females develop from fertilized eggs and are diploid but males develop from unfertilized eggs and are haploid In a colony with a single, singly mated queen, the inclusive fitness of a female (a worker) may be greater if she devotes her energy to rearing reproductive sisters (future queens) than to rearing daughters Why? ♂ A Queen ♀ AB ♂ B ♂ C Worker Worker ♀ AC ♀ BC ♀ AD ♀ CD ♀ BD ♀ CD Drone ♂ D Actor Female Female Male Sister Sister Recipient Daughter Son Daughter Sister Brother r Eusocial hymenoptera are haplodiploid: females develop from fertilized eggs and are diploid but males develop from unfertilized eggs and are haploid In a colony with a single, singly mated queen, the inclusive fitness of a female (a worker) may be greater if she devotes her energy to rearing reproductive sisters (future queens) than to rearing daughters ♂ A Queen ♀ AB ♂ B ♂ C Worker Worker ♀ AC ♀ BC ♀ AD ♀ CD ♀ BD ♀ CD Drone ♂ D Actor Female Female Male Sister Sister Recipient Daughter Son Daughter Sister Brother r ½ ½ 1 ¾ ¼ It would seem that relationships within families should be the epitome of cooperation, since the parent’s fitness depends on producing surviving offspring. However, evolutionary biologists have come to understand that these interactions are pervaded with potential conflict, and that much of the diversity of reproductive behavior and life histories among organisms stems from the balance between conflict and cooperation Mating Systems and Parental Care Whether or not one or both of the parents care for offspring varies greatly among individual species and partly determines the mating system, the pattern of how many mates individuals have a whether or not they form pair bonds Providing care increases offspring survival, which enhances the fitness of both parents. But parental care is also likely to have a cost. It entails risk and it requires the expenditure of time and energy that the parent might instead allocate to further reproduction Infanticide, abortion and siblicide Great Tit Brown Booby Parent-offspring Conflict Parents and offspring typically differ with respect to the optimal level of parental care. A parent’s investment of energy in caring for one offspring may reduce her production of other (future) offspring Production of other offspring increases the inclusive fitness of both the parent and each current offspring. However, the parent is equally related to all her offspring (r=0.5), whereas each offspring values parental investment in itself twice as much as investment in a full sib (r=0.5) Therefore offspring are expected to try to obtain more resources from a parent than it is optimal for the parent to give Selfish Genes Genes that increase in frequency not because they provide an advantage to the organism that carries them but simply because they have an advantage in transmission Genes that promote their own spread at a faster rate than other parts of the genome, can create a context in which there is selection for genes at other loci to suppress their effects. When this is the case, a genetic conflict is said to exist Genomic Imprinting Genomic imprinting in a broad sense is the asymmetric expression of genes with different parental origin Reik and Walter 2001 Genomic Imprinting Genomic imprinting in a narrow sense is the expression of a gene either when maternally inherited only (maternally expressed) or when paternally inherited only (paternally expressed) Reik and Walter 2001 Genomic Imprinting 86 imprinted genes have been identified but recent results indicate that there might be up to 824 imprinted genes only in the brain Gregg et al 2010 data from Gregg et al 2010 Kinship Theory of Genomic Imprinting: Family Matters It applies to genes whose phenotype affects the kin of their carrier Haig 2002 Imprinted genes were first identified as mediators of embryonic and placental growth Moore and Haig 1991, Constancia et al 2004 Formulated in terms of conflict between maternally and paternally inherited genes over the allocation of maternal resources to current embryo (and/or infant) Moore and Haig 1991 Constancia et al 2004 Kinship Theory of Genomic Imprinting: Family Matters If the carrier is equally related to her target kin via its MI and PI genes, these genes do not come into conflict over their combined level of expression Haig 2002, Wilkins and Haig 2003 Monogamy Mother Father Offspring Z R Maternally Inherited Paternally Inherited Current Offspring Future Offspring Kinship Theory of Genomic Imprinting: Family Matters If the carrier is differentially related to her target kin via its MI and PI genes, these genes do come into conflict over their combined level of expression Haig 2002, Wilkins and Haig 2003 Promiscuity Mother Father Another Father Offspring Z R ρ 1– ρ Maternally Inherited Paternally Inherited Current Offspring Future Offspring Kinship Theory of Genomic Imprinting: Family Matters PI genes are favored to extract more maternal resources than MI genes, because the cost of increased resource extraction is incurred by maternal sibs who may not be paternal sibs Haig 1996, Wilkins and Haig 2003 Promiscuity Mother Father Another Father Offspring Z R ρ 1– ρ Maternally Inherited Paternally Inherited Current Offspring Future Offspring Kinship Theory of Genomic Imprinting If these genes can show expression conditional on their parent of origin, genes selected for lower level of expression become silent and genes selected for greater level of expression become expressed at their optimal level: LOUDEST VOICE PREVAILS PRINCIPLE Haig 2002 Resource Enhancer Kinship Theory of Genomic Imprinting What is the predicted direction of the imprint for a resource inhibitor? Resource Inhibitor Kinship Theory of Genomic Imprinting Kinship Theory of Genomic Imprinting Imprinted genes are found mostly in clusters What is the predicted offspring size if there is a deletion affecting a cluster and this is PI? Kinship Theory of Genomic Imprinting Male lion x Female tiger Liger Female lion x Male tiger Tigon 900Lbs 400-300Lbs 275Lbs Growth and Resource Acquisition PLACENTAL INVASION The placenta comprises a fetal portion derived from trophoblasts and a maternal portion derived from the inner layer of the uterine wall Reduced resistance of placental arteries increments maternal systemic circulation through the placenta. The greater the blood flow the through the placenta the greater the transfer of maternal resources to her offspring Growth and Resource Acquisition PLACENTAL INVASION Maternal arteries and placental trophobalst antagonize over the optimal level of resistance: • Maternal arteries become more convoluted to increase resistance • Placental trophoblast cells modify maternal arteries to allow greater blood flow through the intervillous space Growth and Resource Acquisition PLACENTAL INVASION Maternal arteries and placental trophobalst antagonize over the optimal level of resistance: • Maternal arteries become more convoluted to increase resistance • Placental trophoblast cells modify maternal arteries to allow greater blood flow through the intervillous space Growth and Resource Acquisition PLACENTAL INVASION The greater the penetration of the placenta into the myometrium the greater the arterial modification and the blood flow. The paternally expressed IGF2 and expressed in invasive trophoblast cells influence the extent of placental invasion. PI genes are expected to favor a greater modification Growth and Resource Acquisition BLOOD PRESSURE The higher the maternal blood pressure the greater the blood flow through the intervillous space and the transfer of maternal resources to her offspring. One of the most common complications of pregnancy (fatal in developing countries) is pregnancy induced hypertension and its extreme form pre-eclampsia. Pre-eclampsia can be caused by mutations at one of several loci, at least one of which is known to be imprinted —the maternally expressed STOX1 gene. PI genes are expected to favor greater gestational blood pressure than their MI homolog. While the exact role of STOX1 remains unclear, the Kinship Theory would predict that increased expression of STOX1 would reduce maternal blood pressure. Growth and Resource Acquisition NUTRIENT CONCENTRATION IN MATERNAL CIRCULATION After each meal, maternal insulin prompts the uptake of glucose by maternal cells. The longer the glucose remains in the maternal circulation the greater the transfer of maternal resources. During pregnancy, the placenta antagonizes the action of maternal insulin by secreting human placental lactogen (hPL) into the mother’s system. hPL generates resistance to insulin in the maternal cells, thereby elevating the level of glucose in the maternal circulation. This manipulation may be ultimately the cause of gestational diabetes, which occurs late in pregnancy, but generally resolves quickly following delivery. Paternally expressed PLAGL and maternally expressed LOT1, HYMA1 imprinted genes have been linked to gestational diabetes. PI genes are expected to favor greater resistance to insuline than it MI homolog. Post-Natal Behaviour After birth, mammals continue to rely heavily on maternal resources (breast milk and supplemental food), although they are no longer transmitted by means of the placenta. The conflict between the PI and MI alleles shifts primarily into the behavioral arena. Genes expressed in the brain will be under selection to maximize their inclusive fitness, just as they were during pregnancy. Post-Natal Behaviour PRADER-WILLI AND ANGELMAN SYNDROMES Ch 15q11-13 Complete Ch 15 Deletion Ch 15q11-13 Complete Ch 15 Wild Type Deletion Ch 15q11-13 Prader-Willi Syndrome Angelman Syndrome Lethal • AS is associated with enhanced activity, prolonged but poorly coordinated suckling and bouts of laughter among others • Before weaning, PWS is associated with reduced activity, poor suckling, weak cry and sleepiness. After weaning, the child develops an insatiable appetite and becomes obese. Post-Natal Behaviour PRADER-WILLI AND ANGELMAN SYNDROMES The Kinship Theory would predict that: • The increase in the duration of suckling found in AS results from the loss of MI alleles that have been selected to reduce the demand for maternal resources. • PWS is associated with poor food uptake prior to weaning and ravenous food uptake after. o The pre-weaning phenotype may result from the loss of PI alleles that been selected to increase the demand of maternal resources o The post-weaning phenotype may result from an increment in the relative contribution of paternal resources after weaning Complete Ch 15 Complete Ch 15 Deletion Ch 15q11-13 Expression of RE only Angelman Syndrome Deletion Ch 15q11-13 Expression of RI Only Prader-Willi Syndrome Post-Natal Behaviour MATERNAL CARE Peg1 and Peg3, show paternal-specific expression in the brain of adult mice. These genes appear to affect the quality of care that mothers provide to their offspring, as knockouts of these genes result in defects in maternal behaviors of nest building, pup retrieval and placentophagy. Although the phenotype involves the provisioning of maternal resources to offspring, the conflict in this case is between the mother’s two alleles, rather than those of the offspring. The source of this conflict is not obvious, however, since each of the mother’s alleles has an equal chance of being passed to each of her offspring. However, if there is some inbreeding in the population, the offspring could inherit an allele from the father that is identical to one of the mother’s alleles. Under several plausible patterns of inbreeding, the allele inherited from the father is more likely to be identical to the mother’s paternally derived allele than to her maternally derived allele. For example, if the mother mates with her own father (i.e., the father and maternal grandfather are the same individual), the mother’s paternally derived allele will be more closely related to her own offspring than her maternally derived allele will.Evolutionary Game Theory
Evolutionary Game Theory
Evolutionary Game Theory
Evolutionary Game Theory
Evolutionary Game Theory
Evolutionary Game Theory
Evolutionary Game Theory
Sexual Selection
Sexual Selection
Sexual Selection
Sexual Selection
Sexual Selection
Sexual Selection
Sexual Selection
Sexual Selection
Sexual Selection
Sexual Selection
Sexual Selection
Sexual Selection
Sexual Selection
Sexual Selection
Sexual Selection
Sexual Selection
Sexual Selection
Sexual Selection
Social Interactions and the Evolution of Cooperation
Social Interactions and the Evolution of Cooperation
Social Interactions and the Evolution of Cooperation
Social Interactions and the Evolution of Cooperation
Social Interactions and the Evolution of Cooperation
Social Interactions and the Evolution of Cooperation
Social Interactions and the Evolution of Cooperation
Social Interactions and the Evolution of Cooperation
Social Interactions and the Evolution of Cooperation
Social Interactions and the Evolution of Cooperation
Social Interactions and the Evolution of Cooperation
Social Interactions and the Evolution of Cooperation
Social Interactions and the Evolution of Cooperation
Social Interactions and the Evolution of Cooperation
Social Interactions and the Evolution of Cooperation
Social Interactions and the Evolution of Cooperation
Social Interactions and the Evolution of Cooperation
Social Interactions and the Evolution of Cooperation
Social Interactions and the Evolution of Cooperation
A Genetic Battleground: The Nuclear Family
A Genetic Battleground: The Nuclear Family
A Genetic Battleground: The Nuclear Family
A Genetic Battleground: The Nuclear Family
Intragenomic Conflict