Chapter 9 - How species evolve

gene pool

the complete set of alleles present within a particular population

gene

a section of DNA that carries the code to make a protein

allele

an alternate form of a gene

population

a group of individuals of the same species living in the same location

allele frequency

 the proportion of certain alleles in a gene pool

genotype

the genetic composition of an organism at a particular gene locus

phenotype

 physical or biochemical characteristics of an organism, a result of gene expression and the environment

genetic diversity

the variation in genetic makeup or alleles within a population

mutation

a permanent change to a DNA sequence

mutagen

an agent that can cause mutations in DNA

deleterious

alleles that have an overall negative effect on individual fitness when expressed

heritability

 the transmission from parent to offspring, encoded in genes

germline cell

a cell involved in the generation of gametes in eukaryotes

somatic cell

any cell in an organism that is not a germline cell

point mutation

a mutation that alters a single nucleotide in a DNA sequence

block mutation

a mutation that affects a large chunk of DNA, or an entire gene

silent mutation

a mutation in which a nucleotide is substituted for another, changing the codon, but still coding for the same amino acid, no effect on protein structure

missense mutation

a mutation in which a nucleotide is substituted for another, changing the codon and coding for a different amino acid, can effect protein structure

nonsense mutation

a mutation in which a nucleotide is substituted for another, changing the codon to a stop codon, prematurely ceasing translation of the gene's mRNA, effecting protein structure

frameshift mutation

a mutation that involves the insertion or deletion of one or two nucleotides, altering every codon after that

population

a group of the same species living in a particular area at the same time

deletion

Removal of a section of DNA

duplication

Replication (lengthening) of a sequence of DNA

inversion

Reversal of a section of DNA

translocation

Switching of two sections of DNA on different chromosomes

aneuploidy

incorrect number of total chromosomes

polyploidy

 incorrect number of sets of each chromosome

environmental selection pressure

a factor in the environment that impacts an organism's ability to survive and reproduce

competition

interactions between organisms in which both are negatively impacted when competing for the same limited resource, within or between species

natural selection

organisms that are better adapted to their environment have an increased chance of surviving and passing on their alleles

fitness

a measure of how well an organism survives and reproduces in its environment

advantageous phenotype

a trait that increases an organisms fitness in its local environment

selective advantage

an organism with a beneficial allele, which increases its chance of survival against a specific environmental selection pressure

evolution

the change in the genetic makeup of a population over generations

conditions of natural selection

variation, selection pressure, selective advantage, heritability

genetic drift

random events which alter a populations gene pool

gene flow

movement of alleles in and out of a population

bottleneck effect

Occurs when a large proportion of a population is wiped out by a random event

founder effect

Occurs when a small unrepresentative sample of individuals separates from a larger population to colonise a new region and start a new population

speciation

 the process by which populations genetically diverge until they become distinct species

species

able to breed with each other and produce viable and fertile offspring

allopatric speciation

The formation of a new species as a result of a geographical barrier

sympatric speciation

The formation of a new species in populations located in the same geographical location

geographical barrier

a physical factor that prevents gene flow, and stops two populations from breeding together

selective breeding

the process by which humans can select or remove particular traits from a population, by directly controlling the breeding of animals or plants

requirements for selective breeding

variation, selection pressure, heritability