2.1 Scientists

Relative dating: dating a fossil considering the layer of rock in which it was found

Significant scientists to evolutionary theory: darwin , wallace, lamarck, malthus, smith, cuvier

Smith: identified unknown fossils and dated them through which layer of the rock they were in

Cuvier: French zoologist who concluded that many fossils were of extinct organisms as a result of catastrophic events

Lamarck: characteristics acquired during an organism’s lifetime is inherited

Melthus: human race would completely overrun the Earth if it were not held in check by war, famine and disease

Wallace: discovered many new species of insects and reptiles in Asia, proposed the theory of natural selection as the mechanism behind evolution

Darwin: observed similarities and differences in finches and carried out selective breeding in pigeons, published a book on natural selection.

Observations of Darwin and Wallace: members of a species are often different from one another, there are always more children than parents, the size of the population doesn’t change, some offspring don’t survive, offspring look like their parents,

Inferences of Darwin and Wallace: In the struggle to survive, those individuals that are most suited to their environment survive. Those individuals that survive pass their traits on to their children.

Variation: required by natural selection. comes from random assortment of chromosomes during meiosis, random fertilization, crossing over during meiosis, environment, mutagens (introduced new alleles)

Gene pool: all of the genes present within a population. mutations add new alleles to the gene pool, and if they give the organism an advantage then they will be passed down.

Allele frequency: how common an allele is within a population. in mutations, if the allele produces an advantage, the mutate will be more likely to reproduce and have an increased allele frequency. allele frequencies change over time as populations change. can be affected by environmental conditions

Factors affecting alle frequency in a population: immigration, emigration, mutations, natural selection

Process of natural selection: 1. variation, 2. competition/selection pressure, 3. survival of the fittest, 4. survivors reproduce, 5. change in allele frequency, 6. population becomes better suited to its environment.

Characteristics of natural selection: reduces variety because of survival of the fittest- the most favorable characteristic will have the highest allele frequency

Antibiotic resistance: there’s a high number of bacteria with a few that are resistant, antibiotics kill all bacteria (good and bad), the strongest resistant bacteria now have preferred conditions and are able to survive to reproduce and take over, resistant bacteria pass their resistance to other bacteria.

Evolution: change in the heritable characteristics of biological populations over successive generations