Second Exam: Thursday 2 April 2015 Covers Chapters 5, 8, 9, and 10 Lectures 10 to 19 plus Agriculture Global Warming The Vanishing Book of Life on Earth Plastics Intelligent Design? The Weakest Link Technology Economics

Intersexual vs. intrasexual (epigamic) sexual selection Mating preferences in Drosophila and pigeons Certainty of Maternity, Uncertainty of Paternity “Battle of the sexes” Cuckoldry —> jealousy Desertion —> Mating Rituals, Complex Courtship Sex that invests most in most choosy about mates Natural selection produces a correlation between male genetic quality and female preference “Sexy son” phenomenon (females cannot afford to mate with males that are not attractive to other females

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 00 Neither party affects the other __________________________________________________________________

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 —————————————————>

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

Competitive Mutualism

Complex Population Interactions Rob Colwell

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)

“ Cleaner ” fish — Saber toothed blenny

Nudibranchs Green sea slug Hydra

Plant-pollinator, plant seed dispersal (flowers, fruit) Carbohydrate reward (nectar, fruit pulp) Pollinating “vectors” — high degree of plant-animal specificity assures that pollen will not be wasted. Costs versus benefits to both plant and pollinator. Must provide large enough reward to make it worthwhile for pollinator to visit flower, but small enough to assure that the pollinator will continue to look for another flower (in order to move pollen)

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 Grazing in shade Standing in sun Standing in shade Lying in sun Lying in shade Walking ______________________ Total ________________________________________________________

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 Nonassociated Steps, N = 62 Associated Nonassociated Feeding/step, N = 59 Associated Nonassociated __________________________________________________________ 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 _______________________________________________________________________________ Hot-Moistconfusum = castaneum Hot-Dryconfusum > castaneum Warm-Moistconfusum castaneum Cold-Moistconfusum castaneum100 0 _______________________________________________________________________________

Recall the Verhulst-Pearl Logistic Equation dN/dt = rN [(K – N)/K] = rN {1– (N/K)} dN/dt = rN – rN (N/K) = rN – {(rN 2 )/K} dN/dt = 0 when [(K – N)/K] = 0 [(K – N)/K] = 0 when N = K dN/dt = rN – (r/K)N 2

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  ij = per capita competitive effect of one individual of species j on the rate of increase of species i dN 1 /dt = r 1 N 1 ({K 1 – N 1 –  12 N 2 }/K 1 ) dN 2 /dt = r 2 N 2 ({K 2 – N 2 –  21 N 1 }/K 2 ) Isoclines: (K 1 – N 1 –  12 N 2 )/K 1 = 0 when N 1 = K 1 –  12 N 2 (K 2 – N 2 –  21 N 1 )/K 2 = 0 when N 2 = K 2 –  21 N 1 Alfred Lotka Vito Volterra