Leks. Runaway Sexual Selection (Fisher). Handicap Hypothesis (Zahavi) Leks Runaway Sexual Selection (Fisher) Handicap Hypothesis (Zahavi) Sensory Exploitation Hypothesis (Ryan) Alternative mating tactics Internal versus External Fertilization Satellite males (frogs, crickets) Ecological Sexual Dimorphisms Bower birds Ratites Bushland tinamou Lecture # 18 28 March 2018

Female releases eggs first, then male fertilizes them with his sperm, Female has the first opportunity to desert, male is left in a “cruel bind”

Amplexus

Rhea Paternal Care Emu

Ostrich Male Parental Care

Emu Male Parental Care

Dinosaur fossils suggest that male parental care could be ancestral in birds If so, ratites could have retained the ancestral state And, if so, then female care and biparental care would be derived conditions A male of the medium-sized predatory dinosaur Troodon (North America late Cretaceous) brooding a large clutch of eggs. Female archosaurs extract substantial amounts of calcium and phosphorus from their skeletal tissues during egg formation. Histologic examination of cross sections of bones (femur, tibia, and a metatarsal bone) from an adult Troodon found in direct contact with an egg clutch revealed little evidence of bone remodeling or bone resorption, suggesting that the bones were those of a male. Fossilized remains of Troodon and two other types of dinosaurs found with large clutches of eggs suggest that males, and not females, protected and incubated eggs laid by perhaps several females (Credit: Bill Parsons)

13 16 9 20 14 11 15 4 1 7 3 11 5 6

Red-eyed Vireo Ecological Sexual Dimorphism

Four Possible Situations Involving an Individual’s Behavior and Its Influence on a Neighbor __________________________________________________________________ Neighbor(s) Gain Neighbor(s) Lose Individual Gains Pseudo-altruistic behavior Selfish behavior (kin selection) (selected for) Individual Loses True altruistic behavior Mutually disadvanta- (counterselected) geous behavior (counterselected) _________________________________________________________________

W. D. Hamilton (1964). Kin Selection. Inclusive Fitness W. D. Hamilton (1964) Kin Selection Inclusive Fitness Hamilton’s rule: r n b – c > 0 r = coefficient of relatedness n = number of relatives that benefit b = benefit received by each recipient c = cost suffered by donor r n b > c “Adaptive Geometry of a Selfish Herd”

W. D. Hamilton (1964). Died 7 March 2000. Malarial Hemorhagic Fever W. D. Hamilton (1964) Died 7 March 2000 Malarial Hemorhagic Fever “I will leave a sum in my last will for my body to be carried to Brazil and to these forests. It will be laid out in a manner secure against the possums and the vultures just as we make our chickens secure; and this great Coprophanaeus beetle will bury me. They will enter, will bury, will live on my flesh; and in the shape of their children and mine, I will escape death. No worm for me nor sordid fly, I will buzz in the dusk like a huge bumble bee. I will be many, buzz even as a swarm of motorbikes, be borne, body by flying body out into the Brazilian wilderness beneath the stars, lofted under those beautiful and unfused elytra which we will all hold over our backs. So finally I too will shine like a violet ground beetle under a stone. W. D. Hamilton (born 1 August 1936, died 7 March 2000, age 63)

“Adaptive Geometry of a Selfish Herd”

Eusocial Insects. Hymenoptera (“thin wings”) Eusocial Insects Hymenoptera (“thin wings”) Ants, bees, wasps, hornets Workers are all females Haplodiploidly Isoptera (“same wings”) Termites (castes consist of both sexes) Endosymbionts Parental manipulation Cyclic inbreeding

Inclusive fitness should be understood within a multilevel selection approach, as a nested hierarchy extending from genes, to individuals, to kin, and finally to even larger groups.

White-Fronted Bee Eaters, Kenya (Emlen and Wrege, Cornell)

Peter Wrege Steve Emlen

Helpers at the Nest in White-Fronted Bee Eaters in Kenya __________________________________________________________________ Breeders r* Number of Cases % Cases Father x Mother 0.5 78 44.8 Father x Stepmother 0.25 17 9.8 Mother x Stepfather 0.25 16 9.2 Son x Nonrelative 0.25 18 10.3 Brother x Nonrelative 0.25 12 6.9 Grandfather x Grandmother 0.25 5 2.9 Half brother x Nonrelative 0.13 3 1.7 Uncle x Nonrelative 0.13 2 1.1 Grandmother x Nonrelative 0.13 1 0.6 Grandson x Nonrelative 0.13 1 0.6 Great grandfather x Nonrelative 0.13 1 0.6 Nonrelative x Nonrelative 0.0 20 11.5 Total 174 100.0 * r = coefficient of relatedness. S. T. Emlen and P. Wrege, Cornell

Leks. Runaway Sexual Selection (Fisher). Handicap Hypothesis (Zahavi) Leks Runaway Sexual Selection (Fisher) Handicap Hypothesis (Zahavi) Sensory Exploitation Hypothesis (Ryan) Alternative mating tactics Internal versus External Fertilization Satellite males (frogs, crickets) Ecological Sexual Dimorphisms Bower birds Ratites, Bushland Tinamou Reciprocal Altruism Evolution of Self Deceit Subconscious mind Polygraph playback experiments Fool Yourself, The Better to Fool Others

Game Theoretic Approaches. Costs versus benefits of behaviors Game Theoretic Approaches Costs versus benefits of behaviors “tit for tat” strategy can lead to cooperation “the future casts a long shadow back on the present” -- Axelrod Evolutionarily stable strategies = ESS -- Maynard Smith (a tactic that when present in a population, cannot be beaten)

Reciprocal Altruism (Trivers 1971). Donor ––> Recipient Reciprocal Altruism (Trivers 1971) Donor ––> Recipient Small costs, large gains, reciprocated Sentinels Robert Trivers Biological basis for our sense of justice? Friendship, gratitude, sympathy, loyalty, betrayal, guilt, dislike, revenge, trust, suspicion, dishonesty, hypocrisy

Game Theoretic Approaches Prisoner's dilemma: Two suspects, A and B, are arrested by the police. The police have insufficient evidence for a conviction, and, having separated both prisoners, each of them is offered the same deal: if one testifies for the prosecution against the other and the other remains silent, the betrayer goes free and the silent accomplice receives the full 10-year sentence. If both stay silent, the police can sentence both prisoners to only six months in jail for a minor charge. If each betrays the other, each will receive a two-year sentence. Each prisoner must make the choice of whether to betray the other or to remain silent. But neither prisoner knows for sure what choice the other prisoner will make. So the question this dilemma poses is: What will happen? How will the prisoners act?

Prisoner's Dilemma http://plato.stanford.edu/entries/prisoner-dilemma/ Prisoner B Stays Silent Prisoner B Betrays Prisoner A Stays Silent Both serve 6 months Prisoner A serves 10 years Prisoner B goes free Prisoner A Prisoner A goes free Betrays Prisoner B serves 10 years Both serve two years http://plato.stanford.edu/entries/prisoner-dilemma/

Game Theoretic Approaches. Costs versus benefits of behaviors Game Theoretic Approaches Costs versus benefits of behaviors “tit for tat” strategy can lead to cooperation (“the future casts a long shadow back on the present” -- Axelrod) Evolutionarily stable strategies = ESS (a tactic that when present in a population, cannot be beaten) John Maynard Smith

Evolution of Self Deceit. Subconscious mind Evolution of Self Deceit Subconscious mind Polygraph playback experiments

Evolution of Self Deceit. Subconscious mind Evolution of Self Deceit Subconscious mind Polygraph playback experiments Fool Yourself The Better to Fool Others

Summary of Direct Pairwise Interactions Between Two Populations __________________________________________________________________________ Species Type of Interaction A B Nature of Interaction Competition – – Each population inhibits the other Predation, parasitism, + – Population A, the predator, parasite, and Batesian mimicry or mimic, kills or exploits members of population B, the prey, host, or model Mutualism, + + Interaction is favorable to both (can Müllerian mimicry be obligatory or facultative) Commensalism + 0 Population A, the commensal, benefits whereas B, the host, is not affected Amensalism – 0 Population A is inhibited, but B is unaffected Neutralism 0 0 Neither party affects the other __________________________________________________________________

Indirect Interactions Darwin — Lots of “Humblebees” around villages

Indirect Interactions Darwin — Lots of “Humblebees” around villages bees —> clover

Indirect Interactions Darwin — Lots of “Humblebees” around villages bees ——> clover

Indirect Interactions Darwin — Lots of “Humblebees” around villages mice ——o bees ——> clover

Indirect Interactions Darwin — Lots of “Humblebees” around villages cats —o mice ——o bees ——> clover

Indirect Interactions Darwin — Lots of “Humblebees” around villages spinsters —> cats —o mice —o bees —> clover

Indirect Interactions Darwin — Lots of “Humblebees” around villages spinsters —> cats —o mice —o bees —> clover —> beef

Indirect Interactions Darwin — Lots of “Humblebees” around villages spinsters —> cats —o mice —o bees —> clover —> beef —> sailors

Indirect Interactions Darwin — Lots of “Humblebees” around villages spinsters —> cats —o mice —o bees —> clover —> beef —> sailors —> naval prowess

Indirect Interactions Darwin — Lots of “Humblebees” around villages spinsters —> cats —o mice —o bees —> clover —> beef —> sailors —> naval prowess Path length of seven! Longer paths take longer (delay) Longer paths are also weaker, but there are more of them —————————————————>

Indirect Interactions Trophic “Cascades” Top-down, Bottom-up

Competitive Mutualism

Complex Population Interactions Rob Colwell

Mutualistic Interactions and Symbiotic Relationships Mutualistic Interactions and Symbiotic Relationships Mutualism (obligate and facultative) Termite endosymbionts Commensalisms (Cattle Egrets) Examples: Bullhorn Acacia ant colonies (Beltian bodies) Caterpillars “sing” to ants (protection) Ants tend aphids for their honeydew, termites cultivate fungi Bacteria and fungi in roots provide nutrients (carbon reward) Bioluminescence (bacteria) Endozoic algae (Hydra), “kidnapped” chloroplasts Endosymbiosis (Margulis) mitochondria & chloroplasts Birds on water buffalo backs, picking crocodile teeth Figs and fig wasps (pollinate, lay eggs, larvae develop)

Brown Hydra Green Hydra

Nudibranchs Green sea slug Hydra

Runaway Sexual Selection (Fisher). Handicap Hypothesis (Zahavi). Leks Runaway Sexual Selection (Fisher) Handicap Hypothesis (Zahavi) Leks Sensory Exploitation Hypothesis Internal versus External Fertilization Alternative mating tactics Satellite males Ecological Sexual Dimorphisms Ratites (bushland tinamou) Bower birds Spiteful behavior

Summary of Direct Pairwise Interactions Between Two Populations __________________________________________________________________________ Species Type of Interaction A B Nature of Interaction Competition – – Each population inhibits the other Predation, parasitism, + – Population A, the predator, parasite, and Batesian mimicry or mimic, kills or exploits members of population B, the prey, host, or model Mutualism, + + Interaction is favorable to both (can Müllerian mimicry be obligatory or facultative) Commensalism + 0 Population A, the commensal, benefits whereas B, the host, is not affected Amensalism – 0 Population A is inhibited, but B is unaffected Neutralism 0 0 Neither party affects the other __________________________________________________________________

Intraspecific competition (between individuals within spp Intraspecific competition (between individuals within spp.) Interspecific competition (between members of different spp.) Exploitation competition (resource depression) Interference competition (direct antagonistic encounters)

Indirect Interactions Darwin — Lots of “Humblebees” around villages spinsters —> cats —o mice —o bees —> clover —> beef —> sailors —> naval prowess Path length of seven! Longer paths take longer (delay) Longer paths are also weaker, but there are more of them —————————————————>

Euglossine bees Orchid fragrances (epiphytes) Male bees use orchid chemicals as base for production of pheromones to attract female bees (travel up to 23 km) pollinate rare and diverse orchids, allowing sparsely distributed plants to occur at astonishing low densities Dan Janzen

Heliconius tropical butterflies get amino acids from pollen Larry Gilbert

Various Aspects of the Association of Cattle Egrets with Cattle ________________________________________________________ Number of Number Percent Associated Egrets Category of Cattle Cattle Expected Observed ___________________________________________________________________ Grazing in sun 735 39.1 239 439 Grazing in shade 55 2.9 18 21 Standing in sun 146 7.8 48 46 Standing in shade 257 13.7 84 17 Lying in sun 503 26.8 164 69 Lying in shade 143 7.6 47 17 Walking 39 2.1 13 3 ______________________ Total 1878 100.0 612

Various Aspects of the Association of Cattle Egrets with Cattle ______________________________________________________________________ Number of Times Mean Count Was Higher Number Than for Opposite Number of Per Minute Egret Associated Egrets Feedings, N = 84 Associated 2.34 58 69 Nonassociated 1.71 26 31 Steps, N = 62 Associated 20.1 7 11 Nonassociated 32.1 55 89 Feeding/step, N = 59 Associated 0.129 52 88 Nonassociated 0.051 7 12 __________________________________________________________ Harold Heatwole

Interspecific Competition leads to Niche Diversification Two types of Interspecific Competition: Exploitation competition is indirect, occurs when a resource is in short supply by resource depression Interference competition is direct and occurs via antagonistic encounters such as interspecific territoriality or production of toxins

Direct versus Indirect Interactions Exploitation vs. Interference competition Apparent Competition Competitive Mutualism Facilitation Food Chain Mutualism Trophic Cascades (top-down, bottom up) Complex Population Interactions (Colwell’s Plant-Pollinator System) Mutualisms Euglossine bees and orchids Heliconius butterflies (larval nitrogen reserves) Cattle Egret Commensalism Gause’s competition lab experiments

Competitive Exclusion Georgii F. Gause

Coexistence of two species of Paramecium G. F. Gause

Outcome of Competition Between Two Species of Flour Beetles _______________________________________________________________________________ Relative Temp. Humidity Single Species (°C) (%) Climate Numbers Mixed Species (% wins) confusum castaneum _______________________________________________________________________________ 34 70 Hot-Moist confusum = castaneum 0 100 34 30 Hot-Dry confusum > castaneum 90 10 29 70 Warm-Moist confusum < castaneum 14 86 29 30 Warm-Dry confusum > castaneum 87 13 24 70 Cold-Moist confusum <castaneum 71 29 24 30 Cold-Dry confusum >castaneum 100 0 _______________________________________________________________________________

Recall the Verhulst-Pearl Logistic Equation dN/dt = rN [(K – N)/K] = rN {1– (N/K)} dN/dt = rN – rN (N/K) = rN – {(rN2)/K} dN/dt = 0 when [(K – N)/K] = 0 [(K – N)/K] = 0 when N = K dN/dt = rN – (r/K)N2

Inhibitory effect of each individual On its own population growth is 1/K Assumes linear response to crowding, instant response (no lag), r and K are fixed constants

S - shaped sigmoidal population growth Verhulst-Pearl Logistic

Lotka-Volterra Competition Equations. competition coefficient Lotka-Volterra Competition Equations competition coefficient aij = per capita competitive effect of one individual of species j on the rate of increase of species i dN1 /dt = r1 N1 ({K1 – N1 – a12 N2 }/K1) dN2 /dt = r2 N2 ({K2 – N2 – a21 N1 }/K2) Isoclines: (K1 – N1 – a12 N2 )/K1 = 0 when N1 = K1 – a12 N2 (K2 – N2 – a21 N1 )/K2 = 0 when N2 = K2 – a21 N1 Alfred Lotka Vito Volterra