Chapter 3 - EVOLUTION, HEREDITY, AND BEHAVIOUR
Biological evolution: Changes that take place in the genetic and physical characteristics of a population or group of
organisms over time.
Adaptive significance: The effectiveness of behaviour in aiding organisms to adapt to changing environmental
Ultimate causes: Evolutionary conditions that have slowly shaped the behaviour of a species over generations.
Proximate causes: Immediate environmental events and conditions that affect behaviour.
Culture: The sum of socially transmitted knowledge, customs, and behaviour patterns common to a particular group of
Artificial selection: A procedure in which particular animals are deliberately mated to produce offspring that possess
especially desirable characteristics.
Natural selection: The consequence of the fact that, because there are physical and behavioural differences among
organisms, they reproduce differentially. Within a given population, some animals the survivors will produce more
offspring than will other animals.
Reproductive success: The number of viable offspring an individual produces relative to the number of viable offspring
produced by other members of the same species.
Variation: The differences found across individuals of any given species in terms of their genetic, biological (size,
strength, physiology), and psychological (intelligence, sociability, behaviour) characteristics.
Genotype: An organism’s genetic makeup.
Phenotype: The outward expression of an organism’s genotype; an organism’s physical characteristics and behaviour.
Competition: A striving or vying with others who share the same ecological niche for food, mates, and territory.
Genetics: The study of the genetic makeup of organisms and how it influences their physical and behavioural
Heredity: The sum of the traits and tendencies inherited from a person’s parents and other biological ancestors.
DNA (deoxyribonucleic acid): The DNA structure resembles that of a twisted ladder. Strands of sugar and phosphates
are connected by rungs made from nucleotide molecules of adenine, thymine, guanine, and cytosine.
Genes: Small units of DNA that direct the synthesis of proteins and enzymes.
Genome: The total set of genetic material of an organism.
Enzymes: Proteins that regulate the structure of bodily cells and the processes occurring within those cells.
Chromosomes: Threadlike structures in the nuclei of living cells; contain genes
Sex chromosomes: The chromosomes that contain the instructional code for the development of male or female sex
Autosomes: The chromosomes that are not sex chromosomes.
Meiosis: The form of cell division by which new sperm and ova are formed. The chromosomes within the cell are
randomly rearranged so that new sperm and ova contain 23 individual chromosomes, or half of those found in other
Alleles: Alternative forms of the same gene.
Dominant trait: The trait that is exhibited when an individual possesses heterozygous alleles.
Recessive trait: A trait that occurs only when it is expressed by homozygous alleles.
Homozygous: If parents each contribute the same allele for eye colour to their child, the gene combination
Heterozygous: parents contribute different alleles
Polygenic control: influenced by many pairs of genes, not just a single pair
Mutations: Accidental alterations in the DNA code within a single gene. Mutations can be either spontaneous, occurring
naturally, or the result of environmen