20-21. Organismal & Population Ecology

Flashcards covering key vocabulary and concepts from the lecture notes on organismal and population ecology.

Ecology

The study of how organisms interact with each other and the environment.

Organismal Ecology

The branch of ecology that focuses on how individual organisms meet the challenges of their environments.

• Study how organisms are physiologically adapted to their environment/how the environment impacts species’ distributions

• Study how an individual organism’s behavior contributes to its fitness, which, in turn, affects population density (“behavioral ecology”

Ultimate Cause

The adaptive value of a behavior, explaining why a particular behavior evolved in terms of its effect on fitness.

Proximate Cause

The specific genetic and physiological mechanisms underlying a behavior.

Innate Behavior

Behaviors that are genetically programmed and do not require learning.

Examples: spider spinning web, goose rolling egg toward nest

Kinesis

A non-directional movement in response to a stimulus.

Taxis

A directed movement toward or away from a stimulus.

Optimal Foraging Theory

The idea that animals maximize energy gained while minimizing energy expended during foraging

Territory Defense

A fixed area from which individuals or groups exclude others of the same species, often defended through aggressive behavior.

Altruism

A behavior that benefits others at a cost to oneself

Kin Selection

A form of natural selection that favors behaviors that help relatives, enhancing the reproductive success of shared genes.

Population Ecology

The study of how populations of interbreeding individuals grow and what factors affect their growth.

Population Density

The number of individuals of a species in a specific area.

Life Table

A table that summarizes the survival and fertility patterns of individuals in a population across different age classes.

Survivorship Curve

A graph representing the number of survivors in a population for each age class.

Exponential Growth

Rapid population increase that occurs when per capita growth rate remains above zero and resources are not limiting.

Logistic Growth

Population growth that slows as it approaches the carrying capacity of the environment.

r-selected Species

Species that have high growth rates but poor competitive abilities, often leading to high fluctuations in population size and are often characterized by early reproduction and many offspring

K-selected Species

Species characterized by low growth rates and high competitive abilities, stabilizing near the carrying capacity of their environment, typically producing fewer offspring and investing more in parental care.

Population Ecology

Studies how groups of interbreeding individuals (populations) grow, and what factors promote or limit growth

• Abiotic factors: temperature, wind, water, light, salinity, pH

• Biotic factors: species interactions (predation, competition, parasitism)

Community Ecology

Studies how populations of different species interact and form functional communities

• Species richness, community stability, succession

Ecosystem Ecology

Studies the interactions between a biotic community of organisms in an area and the abiotic environment affecting that community

• Nutrient cycling, energy flow/food webs

• Biome

Habituation

A form of non-associative learning in which an organism comes to ignore a repeated stimulus

Associative

A change in behavior that occurs when an organism makes a positive or negative association between a stimulus and a response/behavior (conditioning)

Cognitive (problem-solving)

The ability to solve problems with conscious thought and without direct environmental feedback

Local Movements

Organisms need to move to locate food, water, mates, nesting sites, etc.

Kinesis (local movement)

A movement in response to a stimulus, but one that is not directed toward or away from the source of the stimulus

Example: pill bugs move more slowly in moist environments →keeps them in moist areas

• Random and depends on the intensity of the stimulus.

Taxis (local movement)

A directed movement in response to a stimulus, either toward or away from the stimulus like light, scent, or landmarks

Example: sea turtle hatchlings move toward brightest light — moon reflecting off ocean

Migration

Long-distance seasonal movement, usually between overwintering areas and summer breeding sites

Piloting (migration)

Animal moves from one familiar landmark to the next

Orientation (migration)

Animals have the ability to follow a compass bearing and travel in a straight line

Navigation

Animals have the ability not only to follow a compass bearing but also to set or adjust it

• Cues from sun, magnetic field, smell, etc

Types of Communication

Chemical, auditory, visual, and tactile communication

Promiscuity

A mating system in which individuals have multiple mating partners without forming long-term bonds.

• Maximizes genetic diversity of offspring in unpredictable environments

• Makes it more likely to find a mate of individuals are spread out

Monogamy

A mating system in which an individual has only one mate at a time, often forming a long-term pair bond.

• Can enhance parental investment and increase offspring survival

Polygyny

A mating system in which one male has multiple female partners

• Increased reproductive success for the male and ensuring genetic diversity among offspring. This system can occur in environments where resources are abundant, allowing males to control access to multiple females.

Polyandry

A mating system in which one female has multiple male partners

• Increase genetic diversity and may benefit males by providing additional care for offspring.

3 Major Spacing Patterns

Clumped, uniform, and random

• Clustered resources, competition, and random resources

Age-specific Survivorship

The probability of surviving to a particular age within a population, reflecting the likelihood of survival at various life stages

• # individuals in age class / # individuals in previous age class

Type I Survivorship Curve

A pattern where most individuals survive until old age, showing low mortality early in life

• Common in species like humans and large mammals.

Type II Survivorship Curve

A pattern where individuals have a constant probability of survival throughout their life span, resulting in a linear decline in survivorship

• Common in species such as birds and small mammals

Type III Survivorship Curve

A pattern characterized by high mortality early in life, with few individuals surviving to adulthood

• Common in species like many plants and fish

Inverse density-dependent factors

Factors that increase mortality or decrease reproduction as population density decreases, often limiting population growth regardless of prey abundance.

• Predator taking same # of prey irrespective of population size

Density-independent factors (flat line)

Factors affecting population regardless of density, such as natural disasters or climate, leading to uniform mortality rates

• Physical factors: drought, freezes, floods, fires

Density-dependent factors

Factors that influence population growth based on density, often leading to increased mortality or decreased reproduction as population density rises

• Competition, predation, and disease