Ecology & Evolution Master Review

75 vocabulary flashcards covering key concepts in Ecology and Evolution, including population dynamics, speciation, and community structures.

Analogous structures

Structures with the same function but different evolutionary origins.

Homologous structures

Structures inherited from a common ancestor, even if they serve different functions.

Vestigial structures

Reduced structures that have little or no current function but were functional in ancestors.

Transitional fossils

Fossils showing intermediate traits between ancestral and descendant groups.

Maladaptive trait

A trait that lowers an organism's survival or reproductive success.

Darwin's Theory of Descent with Modification

Species evolve from common ancestors through natural selection.

Herbicide resistance

Resistant weeds survive herbicide, reproduce, and become more common.

Fitness

An organism's ability to survive and leave fertile offspring.

Natural selection

Individuals with advantageous traits reproduce more successfully.

Population

The smallest unit that evolves because allele frequencies change.

Selective pressure

Environmental factor that favors certain traits.

Lamarck's hypothesis

Acquired traits are inherited; this idea is not supported.

Hardy-Weinberg equilibrium

A population is not evolving if there is no mutation, migration, selection, genetic drift, and mating is random.

Hardy-Weinberg equations

$p + q = 1$ and $p^2 + 2pq + q^2 = 1$

Male parental investment

Amount of care males provide offspring.

Harem

One male mates with multiple females.

Sexual selection

Selection based on reproductive success.

Why sexual reproduction is important

Creates genetic variation for natural selection.

Founder effect

Genetic drift caused by a small founding population.

Genetic drift

Random allele frequency changes, strongest in small populations.

Disruptive selection

Favors both extreme phenotypes over the average.

Prezygotic barriers

Prevent fertilization (behavioral, habitat, temporal, mechanical, gametic).

Postzygotic barriers

Occur after fertilization (hybrid inviability, sterility, breakdown).

Hybrid inviability

Hybrid does not survive or develop normally.

Hybrid sterility

Hybrid survives but cannot reproduce (mule).

Hybrid breakdown

Later-generation hybrids have reduced fitness.

Biological species concept

Species naturally interbreed and produce fertile offspring.

Reproductive isolation

Prevents gene flow between species.

Gene flow

Movement of alleles between populations.

Hybrid zone

Area where related populations interbreed.

Vicariance

A geographic barrier splits a population.

Allopatric speciation

Speciation caused by geographic isolation.

Sympatric speciation

Speciation without geographic separation.

Ecological isolation

Species occupy different ecological niches.

Habitat isolation

Species live in different habitats.

Behavioral isolation

Different courtship behaviors prevent mating.

Sexual isolation

Mate preferences prevent interbreeding.

Differentiation

Populations become genetically different.

Polyploidy

Extra chromosome sets; common cause of plant speciation.

Reinforcement

Selection strengthens reproductive barriers.

Phylogenetic tree

Diagram showing evolutionary relationships.

Uniform distribution

Individuals are evenly spaced due to competition or territoriality.

Metapopulation

Separated populations connected by migration.

r-selection

Many offspring, little care, unstable environments.

K-selection

Few offspring, high care, stable environments near carrying capacity.

Clutch size

Number of offspring produced at one time.

Resource specialization

Species use specific resources to reduce competition.

Spatial partitioning

Species use different parts of a habitat.

Competitive exclusion

Two species cannot occupy the same niche indefinitely.

Stable coexistence

Species persist by dividing resources.

Fundamental niche

Potential range without competition.

Realized niche

Actual range after competition.

Interference competition

Direct competition between organisms.

Exploitative competition

Indirect competition by using shared resources.

Intraspecific competition

Competition within the same species.

Exponential growth

Unlimited growth that follows a J-shaped curve.

Exponential growth formulas

$\frac{dN}{dt} = r_{max}N$ and $N_t = N_0e^{rt}$

Logistic growth

Growth slows near carrying capacity.

Logistic growth formula

$$\frac{dN}{dt} = r_{max}N\left(\frac{K - N}{K}\right)$$

Parasites

Organisms living on or in a host.

Pioneer species

First species to colonize disturbed habitats.

Facilitation

Early species improve conditions for later species.

Inhibition

Early species make colonization harder.

Tolerance

Later species establish regardless of earlier species.

Community structure

Composition and abundance of species in a community.

Feeding relationships

Food webs determine energy flow and interactions.

Keystone species

Species with a disproportionately large effect on ecosystem diversity.

10% Rule

Only about 10% of energy passes to the next trophic level; the rest is lost as heat and metabolism.

Nitrogen-fixing bacteria

Convert atmospheric $N_2$ into ammonia usable by plants.

Nitrogen cycle

Movement of nitrogen through the atmosphere, soil, and organisms.

Limiting nutrients

Nitrogen and phosphorus most commonly limit plant growth.

Evolution of parasites

Many evolve to maximize transmission, not rapid host death.

Example: homologous structures

Human arm and whale flipper.

Example: analogous structures

Cactus and euphorbia succulent stems.

Example: hybrid sterility

The mule.