VCE Biology - Unit 4|AoS 2: Evolution

Evolution

Cumulative genetic change in a population of organisms, expressed as the development of new forms or species

Species

Organisms that are able to interbreed to produce viable offspring

Speciation

Evolution of a new species

Fossils

The preserved remains, impressions or traces of organisms found in rocks of different ages

Index (indicator) Fossil

A fossil of known age found in a particular type of sedimentary rock layer that can be used to indicate the age of the deposit at any single locality in which it is found - used to define and identify geological periods

Stratigraphy

Study of the relative positions of layers of rock - lowest stratum is oldest and upper strata are progressively younger

Absolute Dating

Determining the age of a rock directly using radiometric techniques

Radiocarbon Dating

calculating the amount of decay of the carbon isotope carbon-14 based on its half-life

Half-life

The time taken for half of the atoms in a sample to decay

Biogeography

The study of the geographic distribution of organisms

Homologous Features

Features of organisms that have a fundamental similarity in structure (but may have different functions), and provide evidence of common ancestry

e.g. tetrapods all have the same series of bones in their forelimbs

Analogous Features

Have the same function but do not share structural similarity, indicating the similarity is due to an adaptation to a particular lifestyle and not due to common ancestry

e.g. wings in birds and butterflies

Comparative Embryology

Comparison of the form, structure and development of the embryos of organisms

Vestigial Structure

A reduced structure with no apparent function, can be used as evidence of related organisms having diverged from a common ancestor

Thermal Stability

The temperature at which the hybrid molecule dissociates

Molecular Clock

An estimated average rate of nucleotide substitution (number of bases per year) for a particular region of DNA. Based on knowing the age of the oldest fossil related to the two (or more) organisms, or is based on a geological event

Phylogeny

Pattern of how organisms are related through evolutionary descent from a common anestor

Natural Selection

Maintains favourable genotypes in a population, therefore tends to reduce genetic diversity within the gene pool and increase differences between populations, and so those better suited to the environment are more likely to reproduce and pass their alleles to the next generation

Selection Pressure

Any external factor that influences the survival and reproduction of organisms, leading to natural selection.

Biological Fitness

Individuals with the best suited phenotypes to the environment - measured by the relative proportion of fertile offspring left by an individual in the next generation

Adaptation

An inherited characteristic that allows the individual to survive and reproduce

Gene Pool

All genes and allelic forms in a population

Gene Flow

The exchange of genes with other gene pools as individuals move between them. It is a source of new genetic variation and tends to reduce differences between populations

Genetic Drift

Change in frequency of alleles from generation to generation caused by chance (most influential in small populations)

Founder Effect

Loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population

Genetic Bottleneck

Dramatic reduction of the variation present in the gene pool of a population or a species as a result of a sudden and significant decrease in population size

Divergent Evolution

Evolution of different species from a single ancestral species

Convergent Evolution

Independent evolution of structure with similar form and function in unrelated organisms, resulting from similar environmental factors

Adaptive Radiation

Rapid divergence of an evolutionary lineage from a recent common ancestor

Allopatric Speciation

Physical isolation of populations that begins the process of speciation due to geographic isolation