Definition of evolution
The culmination change in the heritable characteristics of a population over time.
Fossil record (definition)
The sum of all discovered and undiscovered fossil and their relative placement in rock
Radioisotope dating
Used to determine the actual timeline of fossils
Evidence of evolution in fossils
- sequence of fossils match sequence that they would be expected to evolve (bacteria and simple algae, then fungi, worms)
- sequence fits with ecology of organisms (plant fossils before animal fossils.. etc.)
- fossils show gradual transition of species into present day species
- transitional fossils which show links between groups/species and show links common to both groups
(Eg. Archaeopteryx: evidence of dinosaurs to birds)
Selective breeding (definition)
The breeding of (domestic) animals and plants for particular traits (by humans)
Selective breeding process
- Populations show variation in traits
- those without traits not allowed to breed
- those with traits are bred, next generation shows increased frequency of the desired traits
- this process is repeated until the entire population showed desired traits
Analogous structures
- have similar functions but have different structures
- no common ancestry
- similar functions are a result of convergent evolution
- for example, bird wings and bee wings: both used for flying, however they have different structures
Convergent evolution
- posed by Darwin?
- the idea that similarities between analogous structures are a result of different organisms adapting to similar environments
Homologous structures
- Similar in structure but different in function
- evidence of common ancestor
- Darwin believed that these structures were a result of similar organisms adapting to different environments
- homologous structures likely evolve once, then adapt to the environment
Vestigial structures
- Remnants of organs that had a function of an early ancestor
- or referred by Darwin as rudimentary organs
Example of homologous structure: Pentadactyl limb (adaptations)
- dolphin fin for swimming
- bat wings for flying
- monkey hand for grasping
- horse hood for galloping
Process of how populations of a species gradually diverge into separate species by evolution (speciation)
- Populations experience different ecological conditions (likely from separation)
- Over many generations, the characteristics of the two populations diverge as a result of natural selection
- The population will meet again however they will not easily mate as
- the mating ritual may be different
- resulting offspring are infertile because of genetic difference - Gene flow between the population is reduced, thus 2 populations are said to have evolved into 2 separate species
Endemic species
Species that is only found in a certain geographic area
Example of natural selection: peppered moths (Biston betularia)
Two types: white type (typical) and black type (melanistic)
Located: England, Europe, North America
Survive by: blending into environment - adult moths camouflage to look like lichens
- When the Industrial Revolution occurred the smoke covering the trees have dark moths an advantage as they could blend into the trees
- Dr Kettlewell predicted that clean forests would have light coloured moths while polluted forests would have dark coloured moths (correct)
Industrial melanism (peppered moths)
Development of melanistic insects in polluted areas
Types of adaptations
- structural: adaptions in the physical features of an organism (colour, size, shape, etc.)
- functional/physiological: adaptations that occur within the body, organs and tissues of an organisms (eg. Stomach)
- behavioural: adaptations in how an organism respond or behaves to Irvine (eg. Running from possible predator)
