Behavioral Ecology

Question 1

behavioral ecology

Answer 1

study of ecological pressures that impact evolution of behavior

Question 2

Four ways evolution has been used to study behavior

Answer 2

1. Historical/phylogenetic approach
2. Testing adaptive value through experimentation
3. Comparative approach
4. Predictive approach

Question 3

Historical/phylogenetic approach

Answer 3

involves reconstructing evolutionary history of behavior –> find behavioral “homologies”

ex. Kettlewell Peppered moth

Question 4

Testing adaptive value through experimentation

Answer 4

involves determining adaptive value of behavior

Question 5

Comparative approach

Answer 5

relies on comparing species w/ similar ancestry but living in different environments AND/OR comparing species with different ancestries but living in similar environments

ex. Darwin’s finches

Question 6

Predictive approach

Answer 6

involves setting up hypotheses derived from evolutionary theory –> testing them with behavioral data from extant species (ex. optimality models)

Question 7

Peppered moth (Kettlewell)

Answer 7

• trend since early 19th century –> peppered moth once mostly light-gray individuals –> now dark gray in industrial areas (light-gray in rural)
• place moths on trunks in both environments –> mark-recapture across 2 nights –> crypsis (camoflauge advantage)

Question 8

Crypsis

Answer 8

camoflage or protective appearence of an animal

Question 9

Of Moths and Men (2002)

Answer 9

• implied Kettlewell comitted fraud, popular with opponents of evolution
• ignores much subsequent research confirming Kettlewell’s results

Question 10

Blue jay (Pietrewicz & Kamil)

Answer 10

• peck if see moth on video, can be trained

Question 11

Convergent evolution

Answer 11

similar selection pressures despite different lineages

Question 12

Divergent evolution

Answer 12

different selection pressures despite same lineage

Question 13

Darwin’s finches

Answer 13

natural selection shaped bills in accordance to diet

Question 14

Cactus & Ground Finches (Peter & Rosemary Grant)

Answer 14

• studied Darwin’s finches for 40+ years
• noticed changes in adaptive success of finches based on environmental changes
• Medium ground finch: 4% increase in beak size across 2-year period due to drought affecting food availability

Question 15

Who said “nature red in tooth?”

Answer 15

Weiner

Question 16

1982 Medium vs. Large Ground Finch

Answer 16

• larger species arrives in Daphne Island –> eats most of the larger, thorny seeds of puncture vine plants – pushing medium finches to rely on smaller seeds
• medium ground finch that did not compete with larger species performed better + more likely to have surviving offspring –> overall smaller beaks

Question 17

Adaptive value of mobbing in gulls (Kruuk)

Answer 17

• Bank swallow & other colonial smallows + Ground nesting gulls: distinct ancestry, shared mobbing behavior (both lay eggs on ground)
• Ground-nesting gulls + Kittiwakes: shared ancestry, divergent behavior (Kittiwake nests on cliffs)

Question 18

Principle of Parsimony

Answer 18

Simpler scenarios involving fewer transitions preferred

Question 19

African Weaver Birds (Crook 1964)

Answer 19

• found that they could be divided into two groups:

GROUP 1 : forest, insectivorous, solitary nests, feed alone in large territories, drab color, monogamous

GROUP 2 : savannah, seed eaters, nest in colonies, feed in flocks, males brightly colored, polygamous

• food abundance and distribution thought to be main selective pressure

Question 20

African ungulates (Jarman 1974)

Answer 20

• divided ungulates into 5 classes (dikdik, reedbuck, gazelle, wildebeest, buffalo)
• organized based on :
• body weight (low –> high)
• habitat (forest –> grassland)
• diet (browsing –> grazing)
• group size (solitary –> herd)
• reproductive unit (pair –> male dominance hierarchy in herd)
• antipredator behavior (hide –> defense)
• Gut size is important component to efficient digestion of foliage
• as body mass increases, volume of gastrointestinal tract increases

Question 21

Kieft (2017)

Answer 21

abundance and diversity of animal-associated microbes scale with individual animal mass

Question 22

Ungulate videos

Answer 22

Plants
* ungulates able to consume with head up to watch for predators
* ungulates form unique niches to reduce competition for resources
* elephants able to reach top of akashia trees with few thorns, stomachs allow for long digestion

Predators
* ears can be rotated to hear sounds from all directions
* noses and sense predators
* head down –> eyes can swivel to see in fron tand behind to sense danger
* predators’ eyes pointed ahead to sense range
* prey stalk predator –> taunt hunter to prevent surprise attack
* North American pronghorn fastest animal for long distances
* jumping use to distort predators
* slim legs –> easy to trip

Question 23

Older hypotheses on egg shape

Answer 23

• clutch size (shapes optimized for sharing warmth in)
• calcium conservation (spherical eggs have less surface area –> conserve calcium where mineral is rare)
• roll factor (conical eggs less likely to roll off cliff)

Question 24

Caswell (2017)

Answer 24

• looked at asymmetry and ellipticity of eggs –> partitioned egg variation among avian orders (largest is Charadriiformes)
• most Charadriiformes live near water + eat invertebrates/small animals
• found that:
  length of egg correlates with bird body size
  shape of egg (asymmetry/elliptical) relates to flying habits
  stronger bird’s flight –> more asymmetrical/elliptical eggs (likely due to pressure on pelvis –> round eggs require wider pelvis)

Question 25

HWI

Answer 25

* "hand-wing index" * measure of wing shape (wing length to width) * high HWI linked to long distance flight ability

Question 26

Spotted Hyenas (Kruuk)

Answer 26

* Serengeti usually nomadic and scavengers * Ngorongoro Crater live in large groups to defend + hunt prey * When prey high in Serengeti, hyenas form social groups + hunt (facultative behavior)

Question 27

Flexible social systems: hamadryas and gelada baboons

Answer 27

* gelada =/= actually baboons * hamadryas part of genus Papio * Papio: social groups, maintain similar social organizations * Hamadryas: large social groups --> split into smaller groups to forage (1 male, many females) * environment influences social structure

Question 28

Testes size and primate mating systems

Answer 28

* correlate body weight w/ testes weight * multi-male reproductive systems tend to overperform (larger testes than projected trend)

Question 29

Correlation between brain size and intelligence: model species

Answer 29

**Dolphins, baleen whales** * **Baleen whales:** mouth type enables filtration, low effort * **Dolphins:** body shape enables herding, requires strategy and coordination

Question 30

Dorsal stripe morphology as an adaptation to predation in Timema walking stick insects (Sandoval & Crespi)

Answer 30

* 2 species, feed on two different leaf types --> white stripe adopted by needle-feeders to blend in * comparative study on all 21 species --> Timema walking sticks evolved dorsal stripe 5-6 times independently (each time associated with shift to needle-like plants) * ecological experiment tests selction w/ & w/o stripes in diff environments --> striped has higher survival on needle leaves

Question 31

Predictive method

Answer 31

setting up hypotheses derived from evolutionary theory --> test with behavioral data from extant spcies natural selection should, over time, make animals efficient at tasks critical to survival & reproduction --> "optimality models" of behavior

Question 32

Behavioral ecology and optimality approaches: animal economics

Answer 32

* currency of fitness (& its proxies) * "decisions" by animals * constraints on decisions * competition * social behavior * predation * sex & mating * reproduction & parental care * costs of adornment & signaling

Question 33

Crows & whelks (Zach)

Answer 33

* coastal crows feed on whelks by dropping them from air onto rocks below --> do the birds use a dropping height that minimizes the total energy expenditure in upward flight? * in general, largest size possible chosen --> break @ lower heights * all eventually plateau at around 5m in # of drops

Question 34

*Animal Behavior* (Alcock)

Answer 34

"This seems adaptive. Case closed." --> assumes must be about genes --> must see differences between environmentally separated groups of crows (exposed to whelks and not) to determine genetic role --> "At first, this behavior appears to be adaptive."

Question 35

Starlings @ the nest (Kacelnik)

Answer 35

* "economics" of foraging * How many items should the parent bring on each trip in order to maximize the rate of delivery of food to the nestlings? * central place foraging (nest) * "Marginal value theorem" - diminishing returns --> plateau

Question 36

Dungfly copulation time (Parker)

Answer 36

* problem of the second male (want to guard to increase chance of parenting offspring) * consider guarding time in optimizing copulation time (before pursuing another female) * predicted: 41 min, observed: 36 min --> lead to issues regarding optimality models' accuracy

Question 37

Critics of Optimality Approaches

Answer 37

* Pierce & Ollason: problem of seeking agreement to models --> poorer data more likely to support models, many fits to predictions might disappear if more data were available

Question 38

Scientific principle of falsifiability (Popper)

Answer 38

* scientific hypotheses can only be empiracally tested by trying to disprove them * however, seeking agreement w/ predicting rather than challenging --> confirmation bias

Question 39

African Golden-Winged Sunbirds: nectar & territoriality (Gill & Wolf)

Answer 39

* undefended flowers --> less nectar for birds/flower * if undefended foraging time = territory foraging time --> no benefit --> sunbirds abandon territorial behavior completely if it becomes uneconomical to defend flowers

Question 40

Evaluating optimality models: advantages

Answer 40

* generate testable, quantitative predictions * assumptions need to be made explicit (ex. starlings optimize rate of delivery)

Question 41

Evaluating optimality models: disadvantages

Answer 41

* what if behavior does not fit prediction? * what if animals are not optimally adapted? (environmental changes, insufficient genetic variation) * "good enough" vs. optimal * assumption of genes "for the behavior" * constraints on optimality