Part II.: Evolution

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Major topics:


chromosome ("coloured body"): the visible bodies within dividing cells that contain DNA and thus carry the genetic information.

chromatid: a subunit of a chromosome, which contains one DNA molecule.

chromosome disjunction: separation of members of homologous chromosomes during meiosis.

gene: a segment of the DNA molecule that codes for a certain character.

locus: the location of a certain gene on the choromosome.

allele: a variant of the same gene.

monohybrid cross: crosses between genotypes with one locus that are heterozygous.

dihybrid cross: crosses between genotypes with two loci that are both heterozygous.

test-cross: cross between a homozygous recessive and an unknown genotype.

back-cross: cross between an offspring (usually the F1) genotype and one of the parental genotypes.

gene pool: the set of all alleles at all loci carried by individuals in a population.

genotypic frequency: the proportion of a given genotype within a population.

allele frequency: the proportion of a certain allele at a given locus within a population.

mutation: random change in the genetic code.

genetic drift: random changes in allele frequencies in a population from generation to generation.

migration(=gene flow): movement of genes beween populations.

inbreeding: mating between relatives

inbreeding depression: loss or decrease of vigor, survivorship, and/or fecundity due to inbreeding.

selection: differential reproduction among differing phenotypes in a population.

heritability: proprotion og phenotypic variation that has a genetic basis.

selection differential: the difference between the mean of the group selected for reproduction and the mean of the entire population.

cline: gradual changes in the phenotype along an environmental gradient.

race: group of populations with similar allele frequencies that are different form those of other populations.

evolution: changes in allele frequencies within a population.

allopatric speciation: species formation from a common ancestor in geograpghically separate locations.

sympatric speciation: species formation from a common ancestor in the same geographical location

industrial melanism: increase in the frequency of the dark phenotype due to industrial pollution.

reproductive isolating barriers: genetically determined (thus heritable) mechanisms preventing gene flow between populations.

polyploidy: the state of having more than two sets of chromosomes.

adaptive differentiation: development of different phenotypes from a common ancestor due to adaptations to different environments.

adaptive radiation: development of several new species from a common ancestor due to adaptations to different environments.

paralell evolution: similar changes in the phenotype between two geographically isolated taxa (species, genera, etc.)

divergent evolution: accumulation of phenotypic differences between two lineages originating from a common ancestor over time.

convergent evolution: development of phenotypic similarities between distantly related taxa over time.

phyletic evolution (=anagenesis): gradual changes in the phenotype without speciation events (splitting or branching) over time.

punctuated equilibrium: sudden development of new phenotypes that stay the same over long period of time.

A little digression in Greek:


mono-: one
di-: two
tri-: three
tetra-: four
penta-: five
hexa-: six

soma: body
allo-: different
sym-: together (see symphony)
patria (Latin): homeland (see patriote)

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