D4.1 Natural Selection (SL)

Vocabulary flashcards summarising major terms, processes, and examples related to biodiversity, natural selection, and evolutionary mechanisms.

Biodiversity

The variety of all living organisms and the ecosystems they form

Natural Selection

Process by which environmental pressures influence the frequency of heritable traits in a population

Heritable Trait

A characteristic encoded by genes that can be passed from parent to offspring

Inherited Variation

Genetic differences among individuals in a population that are transmissible to the next generation

Adaptation

A structural, behavioural, or physiological feature that improves an organism’s survival and reproduction

ICE AGE (mnemonic)

Steps of natural selection: Inherited variation, Competition, Environmental pressures, Adaptation, Genotype frequency change, Evolution

Genetic Variation

The diversity of alleles and genotypes within a population on which natural selection acts

Germline Mutation

DNA change in gametes that creates new alleles in offspring

Crossing Over

Exchange of genetic material between homologous chromosomes during meiosis, producing new allele combinations

Random Assortment

Independent segregation of chromosome pairs during meiosis generating genetic diversity

Random Fertilisation

Chance union of any sperm with any egg, increasing variation among offspring

Gene Flow

Introduction of alleles from one population into another through interbreeding

Overproduction of Offspring

Production of more young than the environment can support, leading to competition

Competition

Struggle between organisms for limited resources such as food, space, and mates

Biotic Potential

Maximum growth rate of a population under ideal conditions

Environmental Resistance

Factors that limit population growth, causing the growth curve to plateau

Carrying Capacity

Maximum population size that an environment can sustain over time

Selection Pressure

Environmental factor (abiotic or biotic) that affects an organism’s ability to survive and reproduce

Abiotic Factor

Non-living component of the environment acting as a selection pressure (e.g., temperature, weather)

Biotic Factor

Living component of the environment acting as a selection pressure (e.g., predators, disease)

Density-Dependent Pressure

Selection pressure whose impact increases with population density (e.g., food scarcity, pathogens)

Density-Independent Pressure

Selection pressure acting regardless of population size (e.g., natural disasters)

PANDA PAW (mnemonic)

Predators, Access to habitat, Nutrient supply, Diseases, Accumulating waste / Phenomena, Abiotic conditions, Weather

Structural Adaptation

Physical feature like a camel’s hump aiding survival in its environment

Behavioural Adaptation

Action or pattern, such as playing dead, that increases survival odds

Physiological Adaptation

Internal process, like hibernation, that enhances survival

Allele Frequency

Proportion of a particular allele among all alleles of a gene in a population

Evolution

Change in allele frequencies in a population over successive generations

Fitness (Evolutionary)

An organism’s ability to produce viable, fertile offspring

Sexual Selection

Selection arising from preference for certain traits that improve mating success, even if costly to survival

John Endler’s Guppy Experiment

Study showing that predation and mate preference drive colour variation in guppy populations

Cichlid Predators

Fish that prey on guppies, favouring drab coloration through natural selection

Epigenetics

Heritable changes in gene expression not caused by DNA sequence alterations

Meiosis

Cell division producing haploid gametes and generating genetic variation