BIO 1106 Unit 4 Exam

Why do animals rely on behavior?

To maintain homeostasis (e.g., finding shade, seeking food) and to ensure reproduction (finding mates, caring for young).

What shapes animal behavior in evolutionary terms?

Natural Selection

What is proximate causation?

The mechanistic “How?” behind behavior—hormones, neurons, physiology, development.

What is physiological analysis?

Study of how internal mechanisms (hormones, neurons) produce behavior.

Example of physiological analysis?

Brain activity differences in schooling vs. non-schooling sticklebacks.

What is ontogeny?

How behavior develops over an organism’s lifetime.

What is ultimate causation?

The evolutionary “Why?” behind behavior.

What is phylogeny in behavior?

How behavior evolved in related species.

Example of phylogeny?

Whether the common ancestor of stickleback populations schooled.

What is adaptive significance?

How a behavior increases survival or reproduction.

Example of adaptive significance?

Why schooling is adaptive in some environments but not others.

What is ethology?

Broad study of animal behavior focusing on proximate causes; includes neuroethology.

What is behavioral ecology?

Study of ultimate causes, especially adaptive significance.

What is associative learning?

Learning by associating two stimuli or a behavior and a reward.

What is classical conditioning?

Stimulus–stimulus association (e.g., Pavlov’s dogs: bell → food).

What is operant conditioning?

Behavior–consequence learning (e.g., Skinner’s rats: lever press → food).

Name four signal modalities.

Acoustic, visual, chemical, tactile (also electrical/vibrational in some species).

What determines signal type?

Ecological constraints (e.g., sound transmission in forests vs. open fields).

Two examples of species‑specific courtship signals?

Firefly flash patterns, frog calls.

What are three functions of communication?

Mate attraction, information sharing, inter-species signaling.

How does natural selection act on communication?

On both actors (signal efficiency) and reactors (resistance to deception).

What types of signals exist?

Ritualized, honest, deceptive (e.g., blue jay mimicking a hawk).

Why do females usually invest more in offspring?

Gestation, lactation, and care require high energy/time.

Consequence of uneven parental investment for females and males?

Females: Choosy about mates.

Males: Compete for many mating opportunities.

What is sexual selection?

Natural selection based on mating success.

What is intrasexual selection?

Competition within a sex, usually male–male (e.g., antlers, size).

What is intersexual selection?

Mate choice, usually female choice (e.g., bright plumage, displays).

What are secondary sexual characteristics?

Sex-specific traits linked to mating systems and investment.

What is monogamy?

One male + one female; common when offspring need extensive care.

What is polygyny?

One male + multiple females; common when males don’t provide care.

What is polyandry?

One female + multiple males; rare; often in resource-rich environments.

What is promiscuity?

Both sexes mate with multiple partners.

What is altruism

Increasing another’s reproductive success at a cost to oneself.

What is reciprocity?

Help now, get repaid later; requires repeated interactions + recognition.

What is kin selection?

Helping relatives to increase inclusive fitness.

What is inclusive fitness?

Direct fitness + indirect fitness.

State Hamilton’s Rule.

c < r × b (cost < relatedness × benefit).

Is true altruism common?

Probably rare and accidental.

Three types of animal groups?

Aggregations, social groups, colonies.

Benefits/costs of group living?

Benefits: Predator detection, dilution effect, cooperative defense, mate finding, food access.

Costs: Attract predators, competition for food/mates/space.

What determines optimal group size?

Balance of benefits vs. costs.

Difference between ecology and environmentalism

Ecology explains interactions; environmentalism aims to reduce human impact

Phenotypic plasticity

Individual-level change during life in response to environment (e.g., thicker fur in winter)

Evolutionary adaptation

Inherited trait shaped by natural selection; plasticity itself can be an adaptation

Population (definition)

A group of individuals of a single species that is demographically, genetically, or spatially separate

Metapopulation

Several populations with limited exchange; occur where suitable habitat is patchy

Three characteristics of population ecology

Population range, pattern of spacing, and how population size changes through time

Uniform spacing

Even spacing; often due to intraspecific competition or behavioral interactions

Random spacing

Rare; individuals have no strong interactions

Clumped spacing

Most common; resources are clumped or unevenly distributed

Population density

Number of individuals per area; density often decreases as organism size increases

Demography

Quantitative study of populations: sex ratio, age structure, fecundity, mortality, generation time

Fecundity

Number of offspring produced in a standard time

Mortality

Death rate in a standard time

Generation time

Interval from birth to reproduction

Exponential growth assumptions

No net migration, unlimited resources, constant intrinsic growth rate, nothing limits growth

Biotic potential (rN)

Intrinsic rate of natural increase; exponential when unchecked

Carrying capacity (K)

Maximum number of individuals the environment can support

Logistic growth

Growth slows as N approaches K

Limitation

A factor that stops population growth (e.g., limited caves for bats)

Density-independent factors

Affect population regardless of density (fires, floods, droughts)

Density-dependent factors

Effects increase with density (competition, disease); create negative feedback

Allee effect

Very small populations grow faster when density increases

K-selected species

Long-lived, few offspring, high parental investment; stable environments, near K

r-selected species

Short-lived, many offspring, rapid reproduction; unstable environments

Human population trend

Long stability, then rapid increase after agriculture, medicine, public health

Highest growth rate

~2% in the 1960s

Highest absolute increase

~1980s because population was larger

Sweden age structure

Rectangular; low birth rate, high survival; stable population

Kenya age structure

Triangular; high birth rate, high mortality; rapid future growth

Inverted age structure

Aging population; shrinking population (e.g., “Do it for Denmark”)

Biological community

All of the organisms that live in one place.

Species richness

The number of species in a community.

Species diversity

A measure combining species richness and relative abundance.

Ecological niche

The total of all the ways an organism uses the resources of its environment.

Fundamental niche

The full range of conditions a species can potentially use.

Realized niche

The actual niche a species occupies due to interactions like competition or predation.

Interference competition

Direct physical interaction between species over a resource.

Exploitative competition

One species uses a resource first, preventing another from accessing it.

Competitive exclusion principle

No two species can occupy identical niches indefinitely when resources are limited.

Resource partitioning

Subdividing a niche so competing species can coexist.

Character displacement

Evolutionary divergence of traits in sympatric species to reduce niche overlap.

Predation

The consuming of one organism by another, including herbivory.

Aposematic coloration

Warning coloration signaling chemical defenses.

Batesian mimicry

A harmless species resembles a toxic or defended species.

Müllerian mimicry

Two or more toxic species resemble each other to reinforce predator learning.

Interspecific Competition

direct physical interaction (fighting).

Exploitative Competition

one species uses resource first, preventing access

Competitive Exclusion

• No two species can occupy identical niches indefinitely when resources are limiting.

• Coexistence possible if:

  • Resources not limiting.

  • Niches differ slightly.

  • Environment fluctuates over time.

Non-Lethal Predation Effects

• Prey avoid risky areas → reduced feeding.

• Stress hormones → lower immunity & reproduction.

Co Evolution

• Reciprocal evolutionary changes between predator and prey.

• strong selection for individuals that can avoid detection or escape a predation attempt, e.g. by speed, agility, or aggressive defenses

• Provides strong selective pressure on the prey population

• Features decrease the probability of capture 

Non-Lethal Predator Effects

• Prey avoid risky areas → reduced feeding.

• Stress hormones → lower immunity & reproduction.

Co-Evolution

• Reciprocal evolutionary changes between predator and prey.

• strong selection for individuals that can avoid detection or escape a predation attempt, e.g. by speed, agility, or aggressive defenses

• Provides strong selective pressure on the prey population

• Features decrease the probability of capture 

Antipredator Adaptions (Plants)

• Morphological defenses: thorns, hairs, sticky secretions, silica.

• Chemical defenses: secondary metabolites (toxins).

Antipredator Adaptions (Animals)

• Chemical defenses: monarch caterpillars store milkweed toxins; poison dart frogs produce alkaloids.

• Value of secondary compounds in diet

• Warning coloration (aposematism) – bright colors advertise toxicity.

• Cryptic coloration – camouflage (inchworm example).

• Defensive coloration: Warning coloration, coloration

Mimicry

• Allows one species to capitalize on defensive strategies for another

• Resemble distasteful/dangerous species that exhibit warning coloration

• Mimic gains an advantage by looking like the distasteful model

Symbiosis

long-term relationship between species.

Keystone Species

Species with disproportionately large effects relative to abundance.

Examples:

• Beavers – dams create ponds → shift entire community.

• Top predators – regulate herbivores → affect plant communities.

Ecological Succession

Communities change from simple → complex over time.

Primary Succession

starts on bare substrate (volcanic rock)