ECCB 205 exam 2

Geometric growth

Discrete population growth model (uses λ), typically applied to populations with distinct breeding seasons

Exponential growth

Continuous population growth model (uses r), suitable for populations with overlapping generations

Logistic growth

Population model with limitation due to carrying capacity (K); growth slows as resources become limiting

Carrying capacity (K)

Maximum population size that can be supported by available resources in logistic growth .

Per capita growth rate

Rate at which each individual in the population increases; highest when the population is small, decreases as it approaches K .

Age structure

Distribution of individuals among age classes in a population; broad-based pyramids indicate growth, narrow indicate decline, straight suggest stability.

Negative density dependence

Per capita growth rate decreases as population density increases (captured by logistic model), often due to limiting resources.

Positive density dependence (Allee Effect)

Per capita growth rate increases as population density increases, occurs at low densities when finding mates or avoiding inbreeding is difficult.

Life history

Schedule of growth, development, reproduction, and survival; organisms allocate time and resources to maximize reproductive success.

Fecundity

Number of offspring produced by an organism per reproductive episode.

Parity

Number of reproductive episodes during an organism's life.

Parental investment

Time and energy given to offspring by parents.

Longevity

Life span of an organism.

Principle of allocation

Resources invested in one trait (e.g., reproduction) cannot be allocated to another (e.g., survival); organisms face trade-offs.

Offspring number vs. size trade-off

Increasing offspring number decreases size/quality; most organisms face this trade-off.

Offspring number vs. parental care trade-off

More offspring means less care per offspring and lower survival, influenced by environmental conditions.

Parental care vs. parental survival trade-off

Having more offspring increases parental effort and can decrease the parent's survival and future reproduction.

"Fast" life history

r-selected species; mature quickly, short lifespan, many offspring, minimal parental care (e.g., fruit flies, weeds).

"Slow" life history

K-selected species; mature slowly, longer lifespan, fewer offspring, high parental investment (e.g., elephants, oak trees).

Trinidadian guppy example

High predation leads to earlier maturity, more offspring but smaller/poorer quality; low predation leads to fewer, larger, higher quality offspring - demonstrates life history trade-offs .

Resource (competition)

Anything an organism consumes/uses that increases population growth rate when more is available; excludes factors like temperature.

Fundamental niche

Full range of conditions under which an organism can survive and reproduce.

Realized niche

Subset of the fundamental niche where an organism actually lives, limited by competition and biotic interactions.

Exploitative competition

Indirect competition for resources (resource competition).

Interference competition

Direct competition, including territoriality or preemption.

Role of abiotic factors

Some species are better adapted to certain abiotic conditions and outcompete others where their preferences overlap.

Apparent competition

Negative effect of one species on another through a shared enemy, not through direct resource competition.

Lotka-Volterra model

Equations modeling predator and prey population dynamics; requires knowing variable meanings and predicting effects on growth rates.

Population cycles

Many predator and prey populations increase and decrease in regular cycles, often due to time delays and interactions (e.g., lynx and hare).

Search efficiency (predators)

Parameter (a) in Lotka-Volterra model; increasing search efficiency means more rapid prey removals, affecting population growth.

Conversion rate (predators)

Parameter (b) in Lotka-Volterra; efficiency of converting consumed prey/resource into offspring.

Stochastic vs deterministic models

Deterministic gives fixed outcomes; stochastic allows randomness and variation in results with the same inputs.

Aposematism

Warning coloration or trait signaling toxicity/unpalatability to predators.

Benefit of sexual reproduction

Creates genetic variation, helping hosts cope with rapidly evolving parasites (Red Queen Hypothesis).

Coevolution

Reciprocal adaptation; two species evolve due to selection pressures from each other, often seen in antagonistic or mutualistic interactions.

Symbiosis

Intimate association between two species living together; can be mutualism, consumer-resource, competition, commensalism, or amensalism.

Endosymbiosis

One organism lives inside another (endosymbiont).

Mutualism

A positive interaction between two species; can aid in defense, resource acquisition, pollination, or seed dispersal.

Generalist mutualist

A species interacting with many other species.

Specialist mutualist

A species interacting with one or a few closely related species.

Obligate mutualists

Require each other to persist, extinction of one can cause loss of the other.

Facultative mutualists

Benefit from each other but interaction is not critical for persistence.

Defensive mutualism example

Acacia trees and ants: ants defend trees in exchange for food and housing.

Coral bleaching

Disruption of coral-zooxanthellae mutualism mainly due to high temperatures; leads to coral starvation or death.

Mycorrhizal fungi

Mutualistic fungi helping plants obtain water/nutrients in exchange for sugars.

Rhizobium-legume mutualism

Bacteria convert atmospheric nitrogen to ammonia in exchange for shelter and food.

Yucca moth/yucca plant

Specialist obligate mutualism: moth pollinates yucca and lays eggs in flower; plant aborts flowers if cost too high.

Climate anomaly

Difference between measured value and a reference or baseline, often used in climate data.

Keeling Curve

Record of atmospheric CO2 increase from pre-industrial mean (278 ppm) to current levels (>400 ppm).

Direct evidence of warming

Instrumental record data (thermometers, satellites) for temperature, sea level, etc.

Proxy evidence

Trees rings, ice core isotopes, etc. used to reconstruct past climates.

Causes of sea level rise

Melting ice on land and thermal expansion of warming sea water.

Biological consequences of climate change

Direct effects on populations (extinction, decline), indirect on interactions (phenology, mismatch); ocean acidification, phenology changes.

Phenology

Seasonal timing of plant and animal life history events (migration, flowering, reproduction, hibernation).

Trophic mismatch

Asynchrony between interdependent species due to climate-driven timing changes (e.g., caribou calving and plant emergence).

Biological responses to climate change

Species may decline/extinct, acclimate (plasticity), shift range, or evolve; each with limits.

Four main greenhouse gases

CO2, methane (CH4), nitrous oxide (N2O), water vapor.