| Definitions Calculations |
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:
numbers:
mono-: one
di-: two
tri-: three
tetra-: four
penta-: five
hexa-: six
etc.
soma: body
allo-: different
sym-: together (see symphony)
patria (Latin): homeland (see patriote)