week 3-4

Question 1

Definition of Lek Mating System

Answer 1

A type of polygyny where males defend a small territory used only for displaying to attract females.
Males gather to display, and females visit the lek to choose a mate, after which they raise young alone.

Question 2

Characteristics of Lek Mating Systems

Answer 2

Males defend tiny, adjacent territories in a lek, with no resources provided to females.
Mating success is highly skewed, with a few males often securing the majority of matings.
Example: Sage grouse – one male may have nearly 50% of copulations in a season.

Question 3

Why Don’t Males Defend Larger Territories?

Answer 3

Females are too dispersed and unpredictable in time – males cannot effectively defend a large area.
Example: Grouse species with lekking males often have females with larger home ranges.
Population density too high for territory defense to be economical – high competition makes large territories unfeasible.
Example: Uganda kob – lek behavior observed only at high population densities.

Question 4

Hotspot Hypothesis

Answer 4

Males gather at areas where females predictably travel, increasing male visibility and attraction.

Question 5

Hotshot Hypothesis

Answer 5

Males gather around a highly attractive male (hotshot), gaining attention from females interested in him.

Question 6

Female Preference Hypothesis

Answer 6

Females prefer large groups of males (leks) as it reduces the time and energy needed to find a mate.

Question 7

Simultaneous Polyandry

Answer 7

One female mates with multiple males who share a territory and defend it jointly.

Question 8

Sequential Polyandry

Answer 8

Female mates with multiple males sequentially, laying separate clutches that each male cares for alone.

Question 9

Why Do Males Accept Polyandry?

Answer 9

Forced by female scarcity – leaving reduces their chances of reproductive success.
Cruel bind – low likelihood of finding a new mate if they desert.

Question 10

polygynandrous System Characteristics

Answer 10

Both sexes have multiple partners simultaneously, with intense sexual competition.
Example: Dunnocks – males and females mate with multiple partners and engage in sperm competition behaviors like cloacal pecking.

Question 11

Polygyny-Threshold Model

Answer 11

Females may accept polygyny if territory quality is high enough to offset the costs of sharing a mate.

Question 12

Infanticide to Reduce Polygyny Costs

Answer 12

Secondary females may kill the primary female’s offspring to increase male care for their own offspring.

Question 13

Sexy-Son Hypothesis

Answer 13

Females may accept polygyny if sons inherit attractive traits from their father, potentially increasing reproductive success.

Question 14

Types of Parental Care

Answer 14

Egg Incubation: Maintaining optimal temperature, preventing desiccation, and aeration.
Example: Birds incubate eggs; sticklebacks aerate eggs by fanning.
Predator Defense: Driving away or warning of predators.
Example: Birds dive-bomb threats near nests.
Feeding Young: Directly feeding at the nest or leading them to food.
Example: Mammals produce milk; pigeons make crop milk.
Sanitation: Removing feces and parasites.
Example: NZ birds are less tidy due to low historical predator risk.
Teaching Skills: Guiding young in finding food and avoiding dangers.
No Parental Care: Eggs left to develop on their own.
Example: Salmon abandon eggs post-spawning.

Question 15

Parental Care Strategies Across Species

Answer 15

Female-Only Care: Common in mammals and lekking species; males often desert post-mating.
Male-Only Care: Seen in polyandrous birds, some fish, and frogs.
Biparental Care: Both sexes provide care, often with varied roles.
Example: Birds and canids, where both parents might incubate or feed young.
Helper-Assisted Care: Non-breeding individuals help a breeding pair, often through kin selection.

Question 16

Kin Selection and Helping Behavior

Answer 16

When individuals are more likelu to behave altruistically to relatives than other species/groups. Kin selection is a type of natural selection that favours the RS of an individuals relatives even at the cost of an own individuals surivial or reproduction

Question 17

Definition of Parental Investment

Answer 17

Any activity that increases offspring survival at the cost of the parent’s future reproductive potential.

Question 18

Costs and Benefits of Parental Care

Answer 18

Parental investment has diminishing returns: past a certain point, extra care yields little benefit to offspring but increases costs to the parent.
Optimal investment (green line) balances parent survival and offspring fitness.
Parent-Offspring Conflict: Occurs when parents invest less than what offspring desire, due to competing future reproductive interests.

Question 19

Brood Parasitism and Extrapair Copulations

Answer 19

Extrapair Copulations: Females mate with additional males, resulting in mixed paternity.
Brood Parasitism: Females lay eggs in others’ nests, either within or between species.
Example: Shining cuckoo lays eggs in grey warbler nests; cuckoo chick mimics warbler’s sounds and scent.

Question 20

Parental Care and Offspring Survival

Answer 20

Parental care boosts offspring survival.
Example: Removing male dark-eyed junco from brood decreases reproductive success.
Survival Rates:
Two parents: 65% survival after 24 days.
One parent: 30% survival.
No parents: 0% survival.

Question 21

Energetic Costs of Raising Young

Answer 21

Caring for young requires high energy for food gathering and predator defense.

Question 22

Increased Predation Risk for Adults

Answer 22

Defending young increases risk of predation, varying by species:
Example: North American (NA) vs. South American (SA) birds:
NA birds, with lower adult survival and larger clutches, take more risks to feed young.
SA birds, with longer lifespans and fewer young, are less likely to take risks.

Question 23

Impact of Nest and Adult Predators on Behavior

Answer 23

Nest Predator (e.g., Blue Jay): NA birds reduce nest visits to avoid detection.
Adult Predator (e.g., Hawk): SA birds avoid risks that threaten their survival, prioritizing future reproduction.

Question 24

Loss of Future Mating Opportunities

Answer 24

Caregiving can reduce opportunities for future matings, creating conflicts:
Example: St. Peter’s fish – mouth-brooding limits female mating chances.
Males more likely to desert if there’s a female-biased sex ratio, while females desert if male-biased.

Question 25

Why Do Females Typically Invest More in Parental Care?

Answer 25

Past Investment (“Concorde” Fallacy): Females have already invested more in eggs, but this alone doesn’t justify ongoing care.
Certainty of Maternity: Females are more certain of their maternity than males are of paternity, reducing the perceived cost of investing in unrelated young.
Lost Mating Opportunities: Males lose more mating opportunities due to faster recovery times between matings.

Question 26

Parental Care in Mammals

Answer 26

Female Care: Universal, mostly due to lactation (97% species).
Male Care (rare): Includes carrying young, defending against predators, or feeding.

Question 27

Parental Care in Birds

Answer 27

Biparental Care: Most common (~90% of species), but females often invest more.
Roles: Incubating, defending young, feeding, and brooding.

Question 28

Parental Care in Reptiles

Answer 28

Absent in most species, except for some crocodilians and Amazon turtles where females provide care by guarding eggs or young.

Question 29

Parental Care in Amphibians

Answer 29

Male-only and female-only care equally common. Rare biparental care.
Example: Some frogs carry eggs to prevent desiccation and predator attacks.

Question 30

Parental Care in Fish

Answer 30

Present in ~20% of fish families with high variability: male-only care most common (9:3:1 ratio of male:biparental

Question 31

Parental Care in Insects

Answer 31

Rare, mostly female-only; male-only care occurs in waterbugs.
Example: Dung beetles (biparental care) prepare brood chambers.

Question 32

paternity Certainty Hypothesis

Answer 32

External Fertilization: Males are more certain of paternity (e.g., sees fertilization), increasing investment likelihood.
Internal Fertilization: Less certainty due to time lag between insemination and laying, leading to lower male investment.

Question 33

Gamete Order Hypothesis

Answer 33

Internal Fertilization: Male can desert post-mating; female is unable to desert until eggs are laid.
External Fertilization: Male remains to fertilize eggs, increasing association with young.

Question 34

Association Hypothesis

Answer 34

Prior association with embryos predisposes a sex to care for young:
Internal Fertilization: Female is closer to offspring (pre-adapted for care).
External Fertilization: Male territory often overlaps with brood, fostering male care.
Example: Sticklebacks build nests and care for eggs, benefiting from both proximity and low opportunity costs for future matings.

Question 35

How Much Parental Care?

Answer 35

The level of parental care depends on weighing costs (energy, predation risk, and lost mating opportunities) against benefits (offspring survival).
The decision depends on:
Condition of Offspring: Health and vigor of the young.
Age of Offspring: Older offspring may be more valuable.
Relatedness: Degree of genetic certainty influences care.

Question 36

Condition of Offspring

Answer 36

Parents invest more in healthy offspring:
Example: Hihi (stitchbird) nestlings with redder mouths (indicating better health) received more food from parents.
Red mouth color linked to better health and enhanced begging display, encouraging more parental provisioning.

Question 37

Age of Offspring and Parental Care

Answer 37

Parental care typically increases as offspring age due to reduced future costs.
Example: Red-winged blackbirds show more aggressive nest defense as chicks grow, diving at perceived threats more intensely over time.

Question 38

Relatedness and Parental Care

Answer 38

Males should ideally adjust care based on genetic relatedness:
Example: Dunnocks—males feed more frequently if they sire more of the offspring.
Counter-Example: Yellow warblers and tree swallows don’t adjust care based on relatedness, despite a high rate of extra-pair paternity.

Question 39

Reasons Males May Not Adjust Care for Unrelated Offspring

Answer 39

Male Care is Essential:
If the benefit of care (increased offspring survival) outweighs the cost of lost paternity, males may continue to care.
Especially relevant in seasonal breeding environments with limited future mating opportunities.
Unawareness of Cuckoldry:
Males can only reduce care if they have information on paternity.
Example: Dunnocks use copulation frequency with a female as an indicator of paternity.
Some females, like chickadees, avoid detection by sneaking extra-pair copulations.

Question 40

Kin Recognition and Parental Investment

Answer 40

Males generally lack mechanisms to recognize kin specifically:
Example: Mexican free-tailed bats use olfactory and vocal cues for recognition, but these cues are learned and not effective for males.
“Green Beard” Hypothesis: Recognition based on unique traits, but open to deception, so not a reliable kin recognition strategy.

Question 41

Intrabrood Conflict

Answer 41

Offspring compete for parental resources because each is more related to itself than to siblings.

Question 42

Interbrood Conflict

Answer 42

Current brood may demand more resources at the expense of future siblings.
Example: Galapagos fur seals—when resources are limited, older pups continue nursing longer, leading to high mortality of newly born siblings.

Question 43

Parent-Offspring Conflict Overview

Answer 43

Optimal investment levels for parents are often lower than what offspring would prefer.
Sibling Conflict and Relatedness:
Greater conflict expected when half-siblings (lower relatedness, r = 0.25) are involved, as seen in birds where half-siblings engage in more aggressive begging behaviors than full siblings (r = 0.5).

Question 44

Can Parent-Offspring Conflict Be Resolved?

Answer 44

Resolution may occur if offspring demands and parental provisioning co-adapt.
Chicks may beg for food to ensure survival; if begging is effective, it may lead to higher provisioning from parents to reduce begging behaviors and protect against predators.

Question 45

Evolution of Behavioral Strategies Against Disease

Answer 45

Animals are in a constant struggle against pathogens and have evolved behavioral strategies to minimize infection risks, including:
Avoiding areas with pathogens.
Avoiding individuals that are infected.

Question 46

Avoiding Pathogen-Filled Habitats

Answer 46

Female grey tree frogs choose oviposition sites based on the presence of Pseudosuccinea snails, which act as intermediate hosts for parasitic trematodes.
They avoid ponds with infected snails, demonstrating a behavioral adaptation to reduce the risk of infection.

Question 47

Avoiding Diseased Individuals

Answer 47

Healthy lobsters avoid communal dens shared with infected individuals, likely using chemical/olfactory cues to detect infections.
Infected lobsters do not avoid healthy individuals, highlighting a social cost of communal living.

Question 48

Selective Foraging to Reduce Parasite Risk

Answer 48

Dik-diks avoid feeding near dung middens to reduce the risk of nematode infections.
They choose foraging sites that minimize exposure to areas where fecal contamination is high, balancing nutrition and parasite risk.

Question 49

“Moving House” to Avoid Parasites

Answer 49

Bluebirds prefer unused nest boxes over previously used ones to reduce ecto-parasite risks, even with competition for limited nesting sites.

Question 50

Sociality and Pathogen Risk

Answer 50

Larger colony sizes correlate with increased flea infestations due to the ease of pathogen spread.
Benefits of social living (predator mobbing, mating opportunities) come with costs of higher disease risks.

Question 51

Spreading Risk through Schooling

Answer 51

In schools, fish experience fewer parasite attacks, showing that larger group sizes can dilute individual risk.

Question 52

Can Animals “Self-Medicate”?

Answer 52

lue tits add aromatic plants to their nests, reducing bacterial richness and improving chick health, illustrating a form of self-medication.

Question 53

Grooming to Reduce Pathogen Load

Answer 53

Birds spend a significant portion of their day preening to manage ecto-parasite loads, with allopreening observed in breeding pairs to reach hard-to-groom areas.

Question 54

Eating Dirt (Geophagy)

Answer 54

Many primates engage in clay consumption, which may help absorb harmful compounds and act as a form of preventative self-medication.

Question 55

Advertising Health through Behavior

Answer 55

Ornamental traits in animals, such as coloration, serve as honest signals of health status to potential mates, influencing mate choice.

Question 56

Health Advertising via Clean Bottoms

Answer 56

The conspicuous white feathers around the cloaca may serve as an advertisement of gastrointestinal health, as maintaining cleanliness would be difficult during infections.