Exam 1, ♥♥♥ 14-Feb. ♥♥♥ If you last name begins with A – L: 116 RAL (right here) If you last name begins with M – Z: 151 EVRT Announcements

Coevolution = The occurrence of genetically determined traits in two or more species selected by the mutual interactions controlled by these traits. -Ricklefs Species Interactions: - Mating (usually -,-) - Competition (-,-) - Predator-prey (+,-) - Mutualism (+,+)

Character Displacement Fig ; Ricklefs “Economy of Nature”

Fig ; Ricklefs “Economy of Nature” Displacement of beak size and diet

What kinds of interactions can lead to character displacement? “Reproductive Character Displacement” Hybridization between species (mate recognition) “Ecological Character Displacement” Competition – for resources

Optimal Threshold Model adapted from Reeve 1989, Starks 2003 signals you want to accept signals you want to reject acceptance errors rejection errors

Dissimilarity between template and cues Frequency Species A Allopatry Dissimilarity between template and cues Frequency Species B Allopatry ???

To avoid costly mistakes (i.e., mating with the wrong species): Signaler Receiver Signal Cue Perception Dissimilarity between template and cues Frequency

Green Tree Frog Hyla cinerea Barking Tree Frog Hyla gratiosa

Sympatry Allopatry Höbel and Gerhardt 2003, Evolution Male Hyla cinerea songs differ In allopatry and sympatry (with H. gratiosa) Sympatry Allopatry Female Hyla cinerea preference differs in allopatry and sympatry Hybrid calls are unattractive!

Irwin et al. 2000, Nature Greenish Warbler, Phylloscopus trochiloides

ABC Birds from A and C respond to each other’s mating calls. Birds of both species at B don’t respond to each other.

“Ring” Species

Response to songs is a function of distance:

2 co-occurring species in the Caribbean One morphologically specialized to trunk life The other specialized for life in the branches

1.A and B live in sympatry A on trunk B on branches 2. No species 3. Species A reintroduced (allopatry with B)4.Species A on trunk and branches Hurricane

Evidence for developmental flexibility Anolis lizards: morphology of hind legs changes when raised on large trunks or small branches. Losos et al Evolution

Anole Rapid evolution of species A? Character displacement when in sympatry? If yes, then what character? Answer: phenotypic plasticity (environment) Species A Long leg and Short leg Species B Long leg and Short leg Species A – long leg Species B – short leg

Brief Recap Green Frogs: displacement of both male call and female preference in sympatry Greenish Warbler: ring species; female call preference in sympatry Sticklebacks: displacement of male preference in sympatry (differentiating from the role of the environment); ultimate and proximate explanations Anoles: competition repressing plasticity

Predation/Parasitism Having your life threatened by another organism is a heavy selection pressure. Getting enough to eat, especially when you are very specialized, is a heavy selection pressure.

Evolutionary Arms Races

BOOM!

The Red Queen Hypothesis Red Queen said to Alice: “…it takes all the running you can do, to keep in the same place.” Lewis Carroll, “Through the looking glass”

Predation/Parasitism Coyotes discover rabbits are food Rabbits that don’t avoid coyotes are eaten Some rabbits are able to hide from coyotes Coyotes can’t catch as many rabbits Some coyotes are able to smell rabbit pheromone Rabbits using the pheromone are eaten Only rabbits that have altered the pheromone live

Predator-Prey, Host-Parasite Coevolution Bat predators are specifically tuned to the songs of their frog prey.

Social parasites mimic recognition properties of their hosts. photograph © Alex Wild 2004

Mutualisms Mutualism = a relationship between two species that benefits both. – Ricklefs Mututalists have complimentary functions –Obligate: they cannot survive without each other –Facultative: they each do better when both are present Obligate mutualisms have been pivotal in major evolutionary advances.

Types of Mutualisms Trophic – partners provide nutrients that can’t be obtained individually. –Digestive bacteria, Lichens Defensive – one partner defends the other in exchange for food, shelter, or etc. –Ants and plants, humans and chickens (?) Dispersive – one partner transports something for the other in exchange for food, or etc. –Pollination