Ecology Exam 3

Extra-pair copulpation

Extra-pair copulpation

when an individual that has a social bond with a mate also breeds with other individuals.​

Mate guarding

a behavior in which one partner prevents the other partner from participating in extra-pair copulations

Sexual Selection

Differential survival and reproduction due to sex-specific traits that are related to reproduction; leads to a variety of differences between males and females.​

Sexual Dimorphism

the difference in the phenotype between males and females of the same species (e.g., body size, courtship behavior

Primary Sexual Characteristics

traits related to fertilization

Secondary Sexual Characteristics

traits related to differences between the sexes in terms of body size, ornaments, color, and courtship

Fecundity-body size ratio

Body size differences between sexes are common in animals; there has been selection for an increased number of gametes or an increase in parental care in one of the sexes.​

Good genes hypothesis

the hypothesis that an individual chooses a mate that possesses a superior genotype.​

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Good health hypothesis

the hypothesis that an individual chooses the healthiest mates.​

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Runaway sexual selection

when selection for preference of a sexual trait and selection for that trait continue to reinforce each other; continues until males run out of genetic variation.​

The handicap principle

the greater the handicap an individual carries, the greater its ability must be to offset that trait.​

Social behaviors

interactions with members of one’s own species, including mates, offspring, other relatives, and unrelated individuals.​

Predator detection/evasion

A group may be able to fend off predators better than an individual.​

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Dilution effect

the reduced, or diluted, probability of predation to a single animal when it is in a group. Probability of death = 1/group size​

vigilance-group size effect

More individuals watching for predators allows each individual to spend less time watching, and more time feeding.​

Food location benefit

many individuals searching for food may be able to find rare food more easily (probability of prey capture increases in a group)

Mate finding group benefit

being social makes it easier to find potential mates because large groups attract the attention of females

Lek

the location of an animal aggregation to put on a display to attract the opposite sex

Consciousness cost of groups

groups of animals are more conspicuous to predators

Disease transmission group costs

The risk of parasites increases in groups; high densities can increase the rate at which diseases spread.​

Competition group costs

Larger groups are better able to locate food, but that food must be shared among all members.​

Aggression

Living in groups can lead to aggression among members.​

Territory

any area defended by one or more individuals against the intrusion of others.​

Dominance hierarchy

a social ranking among individuals in a group, typically determined through contests such as fighting or other contests of strength or skill.

Game Theory: Hawk dove game

Types of social interactions

Every interaction between two individuals has the potential to affect the fitness of both individuals, either in a positive or negative way.

Donor

Recipient

Donor

the individual who directs a behavior toward another individual as part of a social interaction.​

Recipient

the individual who receives the behavior of a donor in social interaction.​

Cooperation

when the donor and the recipient of a social behavior both experience increased fitness from an interaction (e.g., when a herd of lions kill prey).​

Selfishness

when the donor of a social behavior experiences increased fitness and the recipient experiences decreased fitness (e.g., competition for food).​

Spitefulness

when a social interaction reduces the fitness of both donor and recipient (does not occur in natural populations).​

Altruism

social interaction that increases recipient fitness and decreases the fitness of the donor.​

Indirect fitness

the fitness than an individual gains by helping relatives (with which it shares genes through a common ancestor) pass on copies of their genes.​

Inclusive fitness

the sum of direct fitness and indirect fitness

Direct selection

selection that favors direct fitness

indirect selection (kin selection)

selection favoring indirect fitness

Coefficient relatedness

the numerical probability of an individual and its relatives carrying copies of the same genes from a recent common ancestor.​

Eusocial animals four characteristics

1. Several adults living together in a group​

2. Overlapping generations of parents and offspring living together in the same group​

3. Cooperation in nest building and brood care​

4. Reproductive dominance by one or a few individuals, and the presence of sterile individuals​

Caste

individuals within a social group sharing a specialized form of behavior.​

Queen

the dominant, egg-laying female in eusocial insect societies; typically mate once during their lives.​

Haplodiploid

a sex-determination system in which one sex is haploid and other sex is diploid.​

Amensalism

no effect for animal 1, negative effect for animal 2

Commensalism

no effect for animal one, positive effect for animal two

Competition

negative effects for both animals

Mutualism

beneficial for both species

Consumer- resource interactions

• predator prey

• plant/herbivore

• parasitoid/host

• parasite/ host

resources

Any substance or factor that is both consumed by an organism and supports increased population growth rates as its availability increases​

Resource requirements

• Consumed, availability decreases​

• Used for maintenance and growth​

• Reduced availability reduces population growth​

Limiting resource

A resource whose availability quantity cannot meet a population’s requirement for it (carry capacity)

Ectoparasites vs. Endoparasites​

Ectoparasites live on the outside of an organism.​

Endoparasites live inside organisms.

Endoparasites

Intracellular: live inside the cells of a host​

Intercellular: live in spaces between cells of a host​

Emerging infectious disease

a newly discovered or rare disease that increases in abundance.​ (ex white nosed bat syndrome)

Factors that influence the probability of host infection

Mechanism of transmission​

Mode of entering the host​

Ability of parasite to jump between species​

Existence of reservoir species​

Counterattacks to host’s immune system​

Horizontal transmission

when parasite moves between individuals other than parents and offspring

Vertical transmissions

when a parasite is transmitted from a parent to its offspring

Susceptible-Infected-Resistant (S-I-R) model

the simplest model of infectious disease transmission that incorporates immunity.​

S = Number of individuals susceptible to a pathogen​

I = Number of individuals that become infected​

R = Number of individuals that develop resistance​

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b = rate of transmission (via contact) between individuals​

g = rate of recovery and development of immunity​

Susceptible-Infected-Resistant (S-I-R) model (equation)

(SxIxg)/ (Ixb)

SxIxg = rate of infection

lxb = rate of recovery

Coevolution

when two or more species continue to evolve in response to each other’s evolution

Types of mutualisms

• generalists

• specialists

• obligate mutualists

• Facultative mutualists

Generalists

a species that interacts with many other species.​

Specialists

a species that interacts with one other species or a few closely related species.​

Obligate mutualists

two species that provide fitness benefits to each other and require each other to persist.​

Facultative mutualist

two species that provide fitness benefits to each other, but the interaction is not critical to the persistence of either species.​

Mycorrhizal fungi

fungi that surround plant roots and help plants obtain water and minerals.​

Endomycorrhizal fungi

fungi characterized by hyphal threads that extend far out into the soil and penetrate root cells between the cell wall and the cell membrane.​

Ectomycorrhizal fungi

fungi characterized by hyphae that surround plant roots and enter between root cells but rarely enter the cells.​

Arbuscular mycorrhizal fungi

a type of endomycorrhizal fungi that infects a tremendous number of plants including apple trees, peach trees, coffee trees, and grasses.​

Lotka-Volterra Predator/Prey model

a model of predator-prey interactions that incorporates oscillations in predator and prey populations and shows predator numbers lagging behind those of their prey.​

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Lotka-Volterra Predator/Prey model (prey)

dv/ dt = rv - cvp

v= number of prey​

P = number of predators​

c = probability of an encounter between a predator and prey leading to the prey’s capture

Lotka-Volterra Predator/Prey model (predator)

dp/dt = acVp - mp

a = the efficiency of a predator converting consumed prey into predator offspring​

m = per capita mortality rate of predators

Components of Lotka-Volterra Predator/Prey model (prey)

• prey population stable when predator population equals r/c

• If there are more predators when there are more predators than r/c then prey populations are decreasing ​

• When there are less predators than r/c than prey populations are increasing ​

Components of Lotka-Volterra Predator/Prey model (predator)

• When prey population = m/ac then predator population is stable (0)

• ​When prey is greater than m/ac then predator population increases

• ​When prey is less than m/ac then predator population decreases ​

Equilibrium Isoclines

vertical line - predator

horizontal line - prey

Joint population trajectory

the simultaneous trajectory of predator and prey populations.​

Joint equilibrium point

the point at which the equilibrium isoclines for predator and prey populations cross.​

Functional response

the relationship between the density of prey and an individual predator’s rate of food consumption.​

Type 1 functional response

predators rate of consumption rises linear despite prey density (they will always eat all of the prey items ​

Type 2 functional response

when a predator’s rate of prey consumption begins to slow as prey density increases and then plateaus; often happens because predators must spend more time handling more prey or become satiated.​

Any increase in prey density is associated with a slowing rate of prey consumption.​

Type 3 functional response

when a predator exhibits low, rapid, and slowing prey consumption under low, moderate, and high prey densities, respectively.​

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Low consumption at low prey densities may occur for three reasons: ​

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1. Prey can easily find refuges to hide.​

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2. Predators may have less practice at locating and catching prey but develop a search image at higher prey densities.​

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Search image: a learned mental image that helps a predator locate and capture food.​

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3. Predators may exhibit prey switching by changing their diet preferences to the more abundant prey.​

Predator hunting strategies

• active : spend most of their time moving around looking for prey (e.g., birds foraging on lawns for worms).​

• ambush : (sit-and-wait) hunting strategies lie in wait for a prey to pass by (e.g., chameleons waiting for insect prey).​

Prey defenses against hunting strategies

• avoidance (running away, refuge, etc.) - behavioral

• Armor - Physical defense

• Mobbing - behavioral

• Chemical (poison) - behavioral and structural

Crypsis

camouflage that either allows an individual to match its environment or breaks up the outline of an individual to blend in better with the background (e.g., katydids, horned lizards).​

Aposematism

warning coloration

Batesian mimicry

when ​palatable species evolve warning ​

coloration that resembles ​unpalatable species (e.g., hoverflies and hornet clearwings ​resemble the common wasp).​ ( copycat mimic)

Mullerian mimicry

when several unpalatable species evolve a similar pattern of warning coloration (e.g., several species of poison dart frogs have evolved similar warning coloration).​

Acoustic mimicry

mimicking the sounds of a dangerous species when you are not dangerous.

Defenses against herbivores

Structural defenses: sharp spines and hair

Chemical defenses: sticky resins and latex compounds

Tolerance: increases the production of plant tissues