Biology: Adaptations, Thermoregulation, and Population Dynamics

Adaptations

Genetic changes that result in behavioral or morphological variation, allowing organisms to survive in their environment.

Adaptive Fit

The degree to which an organism is suited to its environment.

Macroclimate

Climate variation over large geographic areas that helps shape biomes.

Microclimate

Small-scale climate variation (centimeters to kilometers) involving temperature, precipitation, humidity, etc.

Acclimation

Physiological (not genetic) changes in response to environmental temperature.

Heterotrophs

Organisms that obtain energy by consuming other organisms.

Thermoregulation

Maintenance of a stable internal body temperature despite external changes.

Homeostasis

Maintenance of a relatively constant internal environment.

Heat Balance Equation

Hs = Hm ± Hcd ± Hcv ± Hr - He; describes total heat stored vs. gained/lost through metabolism, conduction, convection, radiation, and evaporation.

Ectothermy

Reliance on external heat sources (cold-blooded).

Poikilothermy

Variable body temperature that changes with the environment.

Endothermy

Generation of heat internally through metabolism (warm-blooded).

Homeothermy

Maintenance of constant body temperature via metabolism.

Basal Metabolic Rate (BMR)

Rate of oxygen consumption representing basic metabolic needs.

Cryoprotection

Production of substances (like glucose) to prevent freezing damage (e.g., wood frogs).

Behavioral Water Conservation

Avoid sweating, store body heat, eat at night, and produce water through respiration.

Inputs and Outputs (Water Conservation)

Inputs: drinking, eating, metabolism; Outputs: urine, feces, evaporation, breathing.

Proximate Causation

Immediate cause of behavior (e.g., flight after alarm call).

Ultimate Causation

Evolutionary reason for behavior (how it increases fitness).

Natural Selection

Process that maximizes gene survival through advantageous traits.

Fitness

Measure of gene survival and reproductive success.

Inclusive Fitness

Total genetic success from both individual reproduction and aiding relatives.

Kin Selection

Helping relatives reproduce to pass on shared genes.

Coefficient of Relatedness (r)

Probability that two individuals share a particular allele by common descent.

Hamilton's Equation

W = d + Σ(i × r); behavior is favored if benefits to relatives outweigh costs.

Altruism

Selfless behavior that benefits others at one's own expense.

Sexual Selection

Selection arising from differences in reproductive investment between sexes.

Intersexual Selection

Female choice based on male traits.

Parental Investment

Energy and resources devoted to offspring.

Operational Sex Ratio

Ratio of sexually competing males to females.

Migration

Seasonal movement between habitats for breeding or resources.

Physiology

Study of the functions of tissues, organs, and organ systems.

Metabolism

Sum of all chemical reactions within an organism.

Catabolism

Breakdown of molecules to release energy.

Anabolism

Use of energy to build or repair tissues.

Metabolic Rate (MR)

Energy used by an animal per unit time.

Assimilation Efficiency

Percentage of consumed energy digested and absorbed.

Gross Production Efficiency

Percentage of consumed energy used for growth or reproduction.

Ectotherms

Animals using external heat; efficient energy use but limited by climate.

Endotherms

Animals generating internal heat; constant temperature but high energy cost.

Kleiber's Law

Metabolic rate increases with body size, but not proportionally (¾ power law).

Temperature-Reaction Relationship

Higher temperatures lead to faster reaction rates.

Small Endotherms

High metabolism and rapid heat loss due to large surface area-to-volume ratio.

Large Endotherms

More efficient at retaining heat due to greater mass.

Population

Members of one species living in a defined area.

Population Size

Number of individuals in a population.

Population Density

Number of individuals per unit area.

Absolute Abundance

Exact number of individuals in a population.

Relative Abundance

Proportion of one species relative to all species in the area.

Demography

Study of population characteristics such as age, sex, and mortality.

Fecundity

Reproductive capacity; rate of offspring production.

Niche

Environmental conditions and resources a species needs to survive and reproduce.

Fundamental Niche

Full range of environmental conditions a species could occupy without competition.

Realized Niche

Actual conditions occupied due to competition.

Dispersal Limitation

Inability to reach suitable habitat due to barriers.

Carrying Capacity (K)

Maximum number of individuals an environment can support.

Population Dynamics

Changes in population size and structure over time.

Discrete Growth

Reproduction in specific seasons or time intervals.

Continuous Growth

Reproduction occurs year-round.

Exponential Growth

Population increases by a constant factor; J-shaped curve.

Logistic Growth

Growth slows as population nears carrying capacity; S-shaped curve.

Survivorship Curve Type I

High survival of young, low survival of old (e.g., humans).

Survivorship Curve Type II

Constant survival rate across all ages.

Survivorship Curve Type III

Low survival of young, high survival of old (e.g., fish).

Competition

Negative interaction where organisms vie for limited resources.

Intraspecific Competition

Competition among members of the same species.

Interspecific Competition

Competition between different species.

Overgrowth Competition

One species physically outgrows another to access resources.

Preemptive Competition

Occupying space or resources first.

Allelopathy (Chemical Competition)

Releasing chemicals that inhibit growth of competitors.

Territorial Competition

Defending a physical area or resource.

Character Displacement (Niche Partitioning)

Species evolve different traits where they coexist to reduce competition.

Competitive Exclusion Principle

No two species with identical niches can coexist indefinitely.

Predation

One organism eats another; transfers energy through the food web.

Lotka-Volterra Model

Mathematical model describing predator-prey population cycles.

Optimal Foraging Theory

Animals maximize energy gain vs. energy spent when seeking food.

Marginal Value Theorem

Describes how long an animal should stay in a food patch before moving on.

Mutualism

Interaction where both species benefit (+,+).

Commensalism

One species benefits while the other is unaffected (+,0).

Facultative Mutualism

Beneficial but not essential for survival.

Obligate Mutualism

Necessary for survival of both species.

Trophic Mutualism

Exchange of energy or nutrients (e.g., coral and algae).

Dispersive Mutualism

Seed or pollen dispersal in exchange for a reward.

Defensive Mutualism

One species protects another in return for food or resources.

Keeler's Model

Evolution of mutualism increases fitness if W(m) > W(nm).

Coevolution

Reciprocal evolutionary changes between interacting species over time.