Ecology and Evolutionary Biology: Biomes, Evolution, Life Histories, Reproduction, Social Behaviors, and Population Distributions

Comprehensive practice flashcards covering core ecological and evolutionary principles from Lectures 06 through 11, including biomes, natural selection, life histories, mating systems, social interactions, and population distribution dynamics.

Permafrost

Soil that remains frozen year-round, characteristic of the tundra biome.

Tundra

A polar biome characterized by dwarf woody shrubs, mosses, lichens, low precipitation ($<600\,\text{mm/year}$), very cold temperatures ($<0^\circ\text{C}$), and permafrost.

Boreal Forest (Taiga)

A biome dominated by evergreen, needle-leaved trees (spruce, pine, fir) with acidic, low-fertility soils, cold temperatures ($<5^\circ\text{C}$), and a short growing season.

Temperate Rainforest

A cool and wet coastal biome characterized by mild temperatures ($4\text{--}12^\circ\text{C}$), high precipitation ($>1{,}400\,\text{mm/year}$), and very large evergreen, needle-leaved trees.

Temperate Seasonal Forest

A temperate biome characterized by distinct seasons, freezing winters and warm summers ($0\text{--}20^\circ\text{C}$), moderate precipitation ($750\text{--}1{,}400\,\text{mm/year}$), and deciduous trees that shed leaves seasonally.

Woodland / Shrubland

A Mediterranean-type biome featuring mild winters, hot dry summers ($7\text{--}25^\circ\text{C}$), low precipitation ($<500\,\text{mm/year}$), and drought-resistant vegetation adapted to frequent fires.

Tropical Rainforest

A warm, high-diversity biome near the equator characterized by year-round warm temperatures ($\approx 25^\circ\text{C}$), very high rainfall ($>2{,}000\,\text{mm/year}$), layered canopy structure, and nutrient-poor soils due to rapid nutrient cycling.

Subtropical Desert

A dry terrestrial biome characterized by hot temperatures ($>20^\circ\text{C}$), low precipitation ($<500\,\text{mm/year}$), shallow infertile soils, and drought-resistant shrubs, cacti, and small trees.

Riparian Zone

The terrestrial band of land directly bordering the edge of a stream or river.

Allochthonous Production

Aquatic biological production relying on nutrients and organic material entering from outside the water body (typical of smaller streams).

Autochthonous Production

Aquatic biological production derived from within the water body itself through internal photosynthesis (typical of larger rivers).

Thermal Stratification

The formation of distinct vertical temperature layers in standing water bodies such as lakes.

Turnover (Aquatic)

The seasonal vertical mixing of stratified water layers in ponds and lakes that redistributes oxygen and nutrients.

Evolution

A change in allele or gene frequencies in a population across generations.

Heritability

The ability of a trait to be passed from parents to offspring genetically, providing the raw material for evolution by natural selection.

Gene Pool

The complete collection of all alleles for all genes present across all individuals in a population.

Polygenic Trait

A single phenotypic trait whose variation is controlled by multiple genes simultaneously.

Pleiotropy

A genetic condition in which a single gene controls or influences multiple phenotypic traits.

Epistasis

A gene interaction where the expression of one gene affects, modifies, or masks the phenotypic expression of another gene.

Genetic Drift

Random, non-directional fluctuations in allele frequencies in a population across generations due to chance events, having a stronger effect in small populations.

Bottleneck Effect

A sharp reduction in a population's size and genetic diversity caused by a catastrophic mortality event where the few surviving individuals rebuild the population.

Founder Effect

A loss of genetic variation occurring when a small number of colonizing individuals establish a new population in a new geographic area with allele frequencies different from the source population.

Fitness

The relative ability of an individual to survive and successfully produce viable, fertile offspring in a specific environment.

Stabilizing Selection

A form of natural selection in which intermediate or average phenotypes experience higher fitness than individuals with extreme traits.

Disruptive Selection

A mode of natural selection favoring both phenotypic extremes over intermediate individuals, driving bimodal distribution.

Directional Selection

A mode of natural selection where individuals possessing one extreme phenotype exhibit higher fitness, shifting the mean phenotype in that direction over time.

Microevolution

Evolutionary changes in gene or allele frequencies that take place within a single population over generations.

Macroevolution

Evolutionary change occurring at or above the species level over long periods of geological time.

Allopatric Speciation

Speciation that occurs when populations are physically separated by a geographic barrier (e.g., mountains, rivers) and diverge genetically over time until they can no longer interbreed.

Sympatric Speciation

The formation of new species without geographic isolation, occurring while populations inhabit the same general area through microhabitat specialization or polyploidy.

Polyploidy

A genetic condition in which an organism possesses three or more complete sets of chromosomes, often resulting from non-disjunction during meiosis and driving rapid speciation.

Life History

The lifetime pattern of growth, development, storage, maturation, and reproduction exhibited by an organism.

Fecundity

The potential reproductive capacity or total number of offspring an individual produces per reproductive bout.

Parity

The number of reproductive episodes or breeding events an organism engages in throughout its lifetime.

"Live Fast" (r-selected) Strategy

A life history strategy characterized by fast growth, early sexual maturity, high fecundity, small offspring size, low parental investment, and a short lifespan.

"Live Slow" (K-selected) Strategy

A life history strategy characterized by slow growth, delayed maturity, producing fewer and larger offspring, high parental investment, and a long lifespan.

Grime's Triangle

A plant life-history classification model defining plant strategies along axes of stress, competition, and disturbance: competitors, stress tolerators, and ruderals.

Ruderals

Plants adapted to high disturbance and low stress that exhibit rapid vegetative growth, early reproduction, and massive seed production (e.g., dandelions).

Principle of Allocation

The ecological rule stating that organisms have a finite pool of acquired resources; resources allocated to one biological function cannot simultaneously be allocated to another.

Semelparity

A life history strategy where an organism expends all its accumulated reproductive effort in a single massive event and subsequently dies ("one and done").

Iteroparity

A life history strategy where an organism undergoes multiple discrete bouts of reproduction across successive seasons over its lifespan.

Senescence

A gradual deterioration of physiological function and reproductive output with advancing age, accompanied by an increasing probability of mortality.

Photoperiod

The predictable daily duration of light exposure that organisms use as an abiotic cue to synchronize seasonal developmental, migratory, and reproductive events.

Timing Mismatch

An ecological phenological disruption occurring when climate change causes shifts in temperatures and food availability out of sync with day-length cues.

Parthenogenesis

A form of asexual reproduction in which an embryo develops directly from an unfertilized egg cell without contribution from male sperm.

Fertilization

The fusion of two haploid ($1n$) gametes (egg and sperm) to create a single diploid ($2n$) zygote.

Muller's Ratchet

The irreversible, cumulative buildup of deleterious mutations in asexual lineages over time, driving genetic load and increasing the risk of extinction.

Red Queen Hypothesis

The evolutionary hypothesis stating that sexual reproduction provides the genetic diversity required for host organisms to constantly adapt in an evolutionary arms race against coevolving pathogens and parasites.

Inbreeding Depression

A reduction in fitness and survival resulting from mating between closely related individuals due to increased expression of deleterious recessive alleles.

Promiscuity

A mating system where individuals mate with multiple partners without forming pair bonds or lasting associations.

Polygyny

A polygamous mating system where a single male mates with multiple females during a breeding season.

Polyandry

A polygamous mating system where a single female mates with multiple males during a breeding season.

Sexual Dimorphism

Phenotypic differentiation in morphological traits (such as size, ornamentation, or coloration) between males and females of the same species.

Handicap Principle

The hypothesis proposing that elaborate, costly, or survival-reducing male traits serve as honest signals of genetic quality because only high-fitness individuals can afford to bear them.

Dilution Effect

A survival benefit of group living where the probability of any single individual being captured by a predator decreases as group size increases.

Lek

A communal display ground where males congregate, establish mini-territories, and perform courtship displays to attract visiting females.

Territory

A defended physical area containing vital resources (food, mates, nest sites) from which conspecific competitors are actively excluded.

Dominance Hierarchy

A structured social ranking within a group determined by competitive interactions that dictates priority access to resources while reducing costly physical fighting.

Direct Fitness

The fitness gained through an individual's own production and survival of biological offspring.

Indirect Fitness

The fitness an individual gains through the reproductive success of non-descendant relatives who carry identical copies of their alleles.

Inclusive Fitness

The total genetic contribution of an individual to future generations, calculated as the sum of direct fitness plus indirect fitness.

Altruism

A social interaction that imposes an energetic or survival cost on the performing donor while delivering a fitness benefit to the recipient.

Hamilton's Rule

The condition under which altruistic behaviors are favored by kin selection, defined mathematically as $C < B \times r$ (or $\frac{C}{B} < r$).

Coefficient of Relatedness ($r$)

The numerical probability that two individuals share an identical allele inherited from a common ancestor (e.g., $0.5$ between parents and offspring).

Eusociality

The most advanced form of social organization, defined by: multiple adults living together, overlapping generations, cooperative brood care, and reproductive division of labor (castes).

Fundamental Niche

The complete range of abiotic physical conditions under which a species is physiologically capable of persisting and reproducing.

Realized Niche

The actual subset of environmental conditions and geographic space a species occupies in the wild due to constraints imposed by biotic interactions like competition and predation.

Ecological Envelope

The predicted range of suitable environmental conditions for a species determined by ecological niche modeling.

Cosmopolitan Species

A species that possesses an exceptionally wide geographic distribution across large portions of the globe.

Endemic Species

A species that is restricted to a single specific, localized geographic area and found nowhere else.

Population Density

The quantity of individuals of a population per unit area or unit volume ($\text{Density} = \frac{\text{Abundance}}{\text{Area}}$).

Lincoln-Petersen Index (Mark-Recapture)

An ecological estimator of total population size ($N$) calculated as $N = \frac{M \times C}{R}$, where $M$ is initial marked individuals, $C$ is total captured in survey two, and $R$ is recaptured marked individuals.

Dispersal Limitation

The inability of an organism to establish in suitable habitats due to physical barriers (such as oceans or mountain ranges) that prevent movement.

Habitat Corridor

A narrow strip of suitable habitat that connects larger isolated habitat patches, facilitating dispersal and gene flow.

Ideal Free Distribution

A theoretical distribution model predicting that individuals distribute themselves among habitat patches in proportion to available resources to maximize individual per-capita fitness.

Metapopulation

A regional network of spatially separated subpopulations of the same species connected by occasional dispersal across an intervening matrix.

Source-Sink Model

A metapopulation framework recognizing unequal patch quality: high-quality source patches produce surplus individuals that emigrate, while low-quality sink patches rely on immigrant influx to prevent local extinction.