Week 6-10

Question 1

Uses of aggressive appearance and behavior

Answer 1

1) Protect food access
2) Protect territory
3) Protect reproductive opportunities

Question 2

Novel environment hypothesis

Answer 2

Hypotheses to explain maladaptive responses to signals (when signals call for mates but also predators)

Current environment is sufficiently different from that in which the behavior evolved that there has not been enough time for a species to adapt

Question 3

Net benefit hypothesis

Answer 3

Hypotheses to explain maladaptive responses to signals (when signals call for mates but also predators)

Sensory mechanism that may result in fitness losses for some individuals under some circumstances but does not erase the fitness gains that receivers derive on average for reacting to a sender in a particular way

Question 4

Sexual selection

Answer 4

Mechanism of evolution that occurs when organisms compete for mates

Can lead to emergence of traits that can expose individuals to predators (decrease survival) but increase reproductive chance

Question 5

Anisogamy

Answer 5

Sexual reproduction where the fusing gametes differ significantly in size

Question 6

All Possible mating structures

Answer 6

• Monogamy (female = 1; male = 1)
• Polygyny (female = 2+; male = 1)
• Polyandry (female = 1; male = +2)
• Polygynandry and promiscuity (female = 2+; male = 2+ )

Question 7

Hypothesis underlying monogamy (3)

Answer 7

1) Mate limitation: hard to find mates
2) Mate guarding: possible to restrict mating of others
3) Mate assistance: hard to raise offspring alone

Question 8

Female defense polygyny hypothesis

Answer 8

(Hypothesis to explain why males are polygynous)

Resources are evenly distributed in space but females form groups to better access those resources or to help dilute the risk of predation, males will follow and guard a group of females

• Crabs with shells

Question 9

Resource defense polygyny hypothesis

Answer 9

(Hypothesis to explain why males are polygynous)

When resources are clumped, attract multiple females, and are easily defensible, males will guard the resources (and by extension the females) by setting up a territory

• African cichlids with shells

Question 10

Lek polygyny hypothesis

Answer 10

When resources are distributed heterogeneously and females are widespread and do not form groups, males will wait for females to come to them

• Topi in lek

Question 11

Scramble competition polygyny hypothesis

Answer 11

When resources are distributed heterogeneously and females are widespread and do not form groups, males will seek out females

Question 12

4 criteria to determine if a species form a lek

Answer 12

1) displaying individuals are spatially aggregated
2) displaying individuals contribute nothing to offspring or their mates beyond gametes
3) choosy sex visits the lek only to mate
4) choosy sex has unrestrained access to mating partners

Question 13

Hotspot hypothesis

Answer 13

(Hypothesis to explain why males congregate at leks)

Males cluster in places (“hotspots”) where the routes frequently traveled by receptive females intersect

Question 14

Hotshot hypothesis

Answer 14

(Hypothesis to explain why males congregate at leks)

Subordinate males cluster around highly attractive males to have a chance to interact with females drawn to these “hotshots”

Question 15

Reproductive insurance hypothesis

Answer 15

Mothers in siblicidal species lay a second egg as insurance against hatching failure

Question 16

What led to the evolution of male water bugs carrying eggs?

Answer 16

Male’s back serves as a good environment for egg incubation/growth

• Large space
• Eggs are at optimal growth when at water-air interphase (too much air leads to desiccation)

Question 17

Mafia hypothesis

Answer 17

Hosts accept brood parasitic eggs out of fear of retaliation by the brood parasite for destroying its eggs

Question 18

Epigenetics

Answer 18

How environmental and behavioral factors can affect how genes work WITHOUT changing the DNA sequence

Question 19

Histone modification

Answer 19

• Changes occur in the histone proteins NOT in the actual genes. It is an example of epigenetic change

Chemical composition of histone proteins alter to regulate gene expression and chromatin structure (affect how tightly DNA is wrapped around histones, which in turn controls whether genes are turned on or off. If tightly wrapped, sections of the DNA will not be expressed.)

Question 20

DNA methylation

Answer 20

Adding a methyl group to nucleotide, which turns off genes and controls gene expression. Methylation recruits repressor proteins or prevents transcription factors from binding to DNA

This does NOT change genetic information. It is an example of epigenetic change

Question 21

Phenotypic plasticity

Answer 21

Ability of an organism to exhibit different characteristics (phenotype) in response to environmental conditions

• Modification of phenotype in response to changing environment

Question 22

Polyphenism (3 types)

Answer 22

Single genotype can produce multiple distinct phenotypes in response to different environmental conditions (outputs are not continuous, but rather discrete and multi-stable)

1) Food induced polyphenism (amount or type of food eaten leads to the production of certain polyphenisms)
2) Socially induced polyphenism (type of social interactions impacts phenotype)
3) Predator-induced polyphenism (presence or absence of predators impacts phenotype)

Question 23

Critical period

Answer 23

A period during someone’s development in which a particular skill or characteristic is believed to be most readily acquired

(Developmental window where individuals learn at an optimal level)

Question 24

Chronotype

Answer 24

Person’s natural inclination with regard to the times of day when they prefer to sleep or when they are most alert or energetic (“When you work best”)

Ex: early bird, third bird, night owl

Question 25

Supercooling

Answer 25

Woolly bear caterpillars survive the winter by supercooling, a process that allows them to survive in subzero temperatures for extended periods of time

• Produce glycerol (and other alcohols), an antifreeze-like chemical, that prevents ice crystal formation
• Produce large molecular mass proteins that prevent ice crystals from forming or break them down to smaller sizes

Question 26

Thermal Hysteresis Proteins (THPs)

Answer 26

Found in many organisms, enabling them to survive in cold environments (supercooling mechanism)

Thermal hysteresis = changing the freezing point of water inside the body

Question 27

Social jet lag

Answer 27

Difference between a person’s internal clock and their daily schedule

(associated with gap between sleep schedules on weekdays and weekends)

Question 28

Zeitgeber

Answer 28

Environmental variables that are capable of acting as circadian time cues

• Ex: Light is the most powerful zeitgeber, resetting the circadian clock to match the 24-hour day. Light-sensitive receptors in the retina send signals to the brain, which can cause you to wake up in the morning or sleep at night
• Ex2: Social interactions…. personal relationships, meals, exercise, and social demands can entrain biological rhythms like sleep, hormone levels, and temperature.
• Ex3: Food availability… when you eat can affect your circadian rhythm