Evolution Biology

MANIFESTING A++

gradualism

gradualism

Proposed by Darwin, proved Lamarck’s theory of use and disuse wrong - over long periods of time, small changes/adaptations accumulate (instead of an organism’s lifetime, it’s over generations of organisms that changes and characteristics accumulate)

gene flow

the transmission of genes across populations. It is the transfer of alleles or gametes from one population to another

• Eg. a bee carrying pollen from one flower population to another, or a caribou from one herd mating with members of another herd

punctuated equilibrium

basically states that contrary to Darwin’s theory, evolution occurs in short spurts of speciation followed by lengthy periods of isolation (equilibrium) when a gene pool is in equilibrium, the frequency of these alleles are constant over time

natural selection

The opposite of genetic drift. Organisms with more favorable traits survive better and reproduce more, passing on their genes. A mechanism of evolution, causing species to change and diverge over time. (causes adaptations)

Adaptation

how organisms change over time to suit their environment and reproduce well

Mutation

new alleles pop up due to mistakes in DNA

Random mating

The mating between two organisms is not influenced by any environmental, hereditary or social interaction

genetic drift

Genetic drift, also known as allelic drift or the Wright effect, is the change in the frequency of an existing gene variant in a population due to random chance.

Allele frequency

how common an allele is in a population

Sexual selection

natural selection arising through preference by one sex for certain characteristics in individuals of the other sex. (remember the video of the spiders or moonwalking bird)

Variation

the magnitude of genetic differences in a population

Evolution

a process that results in changes in the genetic material of a population over time.

Fitness

More favorable traits/capacity to reproduce successfully

Fossil

any preserved remains of an animal from a past geologic time period (hard parts are usually the most to be preserved, eg. teeth, bones, shells, etc.)

Convergent evolution

two unrelated populations developing similar characteristics due to a similar environment/habitat

Divergent evolution

two or more populations with ancestral relations develop different characteristics/adaptations due to a different environment/habitat

Lamarck

proposed the incorrect theory that organisms acquire characteristics and that these characteristics can be passed to their offspring, inspiring Darwin on adaptation

Hutton

Geological forces form features (ie. mountains). Forces beneath the earth can push rocks upwards.

Lyell

processes that changed earth in the past are still ongoing today

Proposed uniformitarianism - earth’s geological structure results from observable processes that cycle (Lyell).

Uniformitarianism

earth’s geological structure results from observable processes that cycle (Lyell).

Malthus

If populations grew unchecked there would be more competition for resources and living space. Forces that worked against population included warfare, famine, disease. inspired Darwin into believing that this could be applied to all organisms

Charles Darwin

Descent with Modification - today’s species descended from ancestral species. Depending on where the modern species are up they adapted to the environment.

Natural Selection

Individuals with more favorable traits in a certain environment leave more offspring than other individuals

Embryology

The study of the development of embryos; comparison among different populations (the more similar the embryo, the more closely related their ancestors are) - type of evidence of evolution

Molecular Biology

Count differences in cytochrome c/amino acids among different species/organisms - type of evidence of evolution

Homologous

Structure is similar, function differs (eg. different limbs of different organisms, like human arm vs

Analogous

Function is same, structure differs

Vestigial

structures that are no longer used by the organism (wisdom teeth, tailbone, etc.)

fossil evidence

Oldest layer is the bottom-est layer, youngest layer is the layer closest to the surface/top

Artificial (man-made) Selection

Parent plants w/ desired characteristics are selected from a mixed population and are bred together. From the offspring, those with the desired characteristics are also bred together repeatedly over several generations until all offspring possess the desired trait.

Microevolution

evolutionary change within a species or small group of organisms, especially over a short period.

Genetic drift

A change in the gene pool due to chance (a change in allele frequencies), the smaller the generation the greater the effect of genetic drift on the population (ie. a couple w/ blue and green eyes has babies, offspring with either blue or green eyes, a storm kills off all white rabbits in a white-brown mixed population).

Founder Effect

when a small group splits off from the main population to found a colony, causing a loss of variation in the population

Bottleneck Effect

The decrease of size of a population due to natural disasters or human activities (specicide, human population planning, etc.)

Gene flow

Changes in allele frequency due to mixing with new genetically different populations

Mutations

new alleles pop up due to mistakes in DNA

Convergent

two unrelated populations developing similar functions due to a similar environment/habitat (eg. sharks and dophins don’t have a common ancestor, but have similar body structure)

Divergent

two or more populations with ancestral relations develop different functions due to a different environment/habitat

Coevolution

when one species develops with another (ie. a flower changes shape, a bird’s beak changes shape to suit the flower to suck the nectar)

Sexual selection

natural selection arising through preference by one sex for certain characteristics in individuals of the other sex. (remember the video of the spiders or moonwalking bird)

More attractive = more likely to find mate = reproducing more, occurs more in offspring = occurs more in population

Stabilizing

average form of a characteristic is favored, neither extreme (gray bunnies over white or black)

Directional

one extreme form of a trait is favored(white bunnies over black)

Disruptive

both extreme forms of a trait are favored over average (white and black bunnies over gray)

Species

a group of organisms that can reproduce with one another in nature and produce fertile offspring.

reproductive barriers

barriers, prezygotic and prozygotic that prevent members of different species from reproducing

geographical isolation

2 populations are physically separated by barriers (rivers, mountains, bodies of water)

Behavioral isolation

Two populations are capable of interbreeding/Differences in mating rituals prevent interbreeding (ie. similar birds won’t mate b/c they have different songs)

Temporal isolation

Different breeding seasons/breed at different times of the day

Mechanical isolation

Reproductive structures are incompatible.

Speciation

the formation of a new species, occurs whenever reproductive isolation stops (see above)

Habitat isolation

even if two organisms live in the same area, they may be separated based on environmental needs (if two amphibians of the same species are in the same area but one prefers aquatic environments and the other prefers terrestrial environments, they are isolated.