Evolution

Brussel sprouts, broccoli, cabbage, and kohlrabi are all from the same species (wild cabbage) but are artificially selected for particular traits.

• Individuals in a population vary.
• Some of this variation in heritable.
• Not all individuals survive and reproduce equally well.
• Non-random subset of population survives and reproduces better than others.

Midoffspring is the mean of all offspring of a given set of parents for some trait (such as beak depth). Midparent is the mean of both parents for the given trait in question.

Heritability can be inferred by the degree that offspring resemble their parents.

• NS and Evo are dynamic (not random, but not “progressive” either).
• NS acts on individuals within a generation. Evo acts on populations between generations.
• NS acts on a phenotype. Evolution consists of changes in genotype frequencies.
• NS and Evo are not “forward looking”. NS is imperfect.
• NS is neither moral or immoral. NS acts on individuals, not “for the good of the species” because selfish mutants can invade population.

Individuals; within … phenotypes

Populations; between … genotypes

That there is variation in the population, and that this variability is heritable.

That not all individuals survive and reproduce equally well and that this different in fitness is non-random (i.e. consistently happens to orange flowers).

Mutations

• Environmental stress (radiation, chemical mutagens)
• Imperfect cellular processes (mistakes in DNA replication)
• Heritability of mutations (somatic vs germline, strictly germline heritability)

• Point mutation
• Chromosome inversion
• Gene duplication
• Genome duplication

A point-mutation of a nucleic acid that does not result in a change in amino acid in the final product.

A point-mutation of a nucleic acid that results in a change in amino acid in the final product.

A type of non-synonymous mutation that renders the protein product non-function.

A type of non-synonymous mutation that changes the nucleic acid sequence into a stop codon, prematurely stopping transcription and resulting in an incomplete protein.

A type of non-synonymous mutation that changes a stop codon into a non-stop codon, resulting in a much longer transcription and most likely a non-functional protein.

An insertion or deletion of a number of nucleotides other than multiples of three that cause the transcriptional factors to shift where each codon is read, resulting in a drastically different transcription, and therefore a likely non-functional protein.

An insertion or deletion of 3, 6, 9, 12 (and so on) nucleotides that doesn’t shift the reading of the gene, but still results in new amino acids being mixed into the protein, resulting in a possibly altered or non-functional protein.

A type of non-synonymous mutation that changes the amino acid, but the change is a neutral one that has no bearing on the protein at large.

• Deletions
• Duplications
• Inversions
• Translocations

An abnormal number of chromosomes, usually caused by a non-disjunction.

Is the failure of chromosomes to properly segregate.

The segment of DNA that is inverted is read backwards. The segment also cannot properly cross-over with the homologous chromosome.

Unequal crossing-over.

The extra copy of the gene is free to mutate as much as it wants without taking away the effect that the other copy of the gene has. It’s a great source of new genes. Dimers are also often the result of gene duplication.

Large effect mutations are nearly always deleterious. Small effect mutations are usually a lot less deleterious, and sometimes may even be beneficial.

Housekeeping genes maintain required transcription in the cell. A mutation usually results in death, so mutations are rare in such genes.

Male gametes are constantly produced throughout the life of a male, while female gametes are produced only once in the beginning of life, then stored. Mutations can accumulate in female gametes. However, such mutations can also cause the egg to not be released, or to malfunction. Female gametes are more susceptible to mutations that prevent the formation of a zygote than male gametes.

The balance theory states that heterozygosity is mostly beneficial, while the neutral theory states that most alleles are equivalent and maintained by genetic drift instead.

Unpredictable/changing environments might increase mutation rates in a given population if there is enough variability among individuals for mutation rate (i.e. different individuals have different efficiencies of proofreading mechanisms). So long as that variation is heritable, then natural selection might select for individuals that mutate more because they come across a phenotype better adapted to new environment faster than those individuals that mutate slower.

• No mutation
• No migration
• No sex selection
• No genetic drift
• No unequal fitness

• Absolute fitness – W
• Relative fitness – w

Concerning a particular genotype, it is the ratio between the number of individuals with that genotype after selection to the number of individuals with that genotype before selection.

Relative fitness is the average number of surviving progeny of a particular genotype compared with the average number of surviving progeny of competing genotype after one generation.

The starting frequencies and the strength of selection.