PSYC 3280 Lecture Notes - Lecture 2: Genetic Drift, Genetic Variation, Motility
26 Sep 2018
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Lecture 2- The Evolution of Behaviour
Animals
• Mostly motile (moving), ingests other organisms
• Phenotype- observable trait
• Genotype- Genetic makeup
o 23 pairs chromosomes: 22 homologous pairs and 1 pair of sex
chromosomes
o the form of a gene is called an allele
• Phenotype = Genotype + Environment
• Genetic variation is what results in new alternatives (the basis of
evolution)
Genetic Variation
• Mutations- can be beneficial or deleterious
• Sexual Reproduction- the body (somatic) cells have 2 pairs of
homologous chromosomes, but the gametes (sperm/egg) have only one
copy
o When sperm and egg combine, they create a new DNA
combination with a different phenotype than the parents
• Mutation + Sexual Reproduction = Variability of a species
• Evolution = natural selection + sexual selection + gene flow (migration) +
genetic drift (new colonizers, or inbreeding due to small population
sizes)
Natural Selection
• Direct Fitness- number of offspring produced compared to other species
• Reproductive Success- # born, # weaned, # survived to mate
