evolution notes

theory of evolution

the theory in biology about the various types of organisms on Earth and have distinguishable differences are due to modifications in successive generations

who is the founder of the modern evolutionary theory?

Charles Darwin

where did charles darwin start his research and why?

the Galapagos because of the great amount of variation between the animals on the island

artificial selection

an evolutionary process in which humans consciously select for or against particular features in organisms, like selective breeding

observations Darwin made in the Galapagos:

* members of a population vary greatly in their traits
* traits are inherited from parents to offspring
* all species are capable of producing more offspring than an environment can support
* variations that cause greater reproductive success more likely to be passed on than those with less success

natural selection

organisms with favorable traits tend to survive and reproduce, while those who don’t, don’t

fitness

the ability to survive and reproduce

adaptations

traits enriched in a population that increase the fitness of an organism

why does evolution occur ?

it occurs because of natural selection, it is a natural mechanism for change where favorable traits are more likely to be passed on through reproduction where unfavorable ones are not

principles of the evolutionary theory

* evolution occurs because of natural selection
* the ability of an organism to survive and reproduce and survive in its environment is known as fitness
* as organisms survive and adapt speciation may occur
* the failure of an organism’s ability to adapt will eventually lead it to extinction because of natural selection

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adaption

any trait that aids in survival and reproduction

speciation

the formation of new species

evidence for evolution

* fossil types: imprints, molds/impressions, casts, bones, shells
* can be used to deduce the sequence of changes that occurred in a species or group of organisms over time
* transitional fossils are in between ancestral and descendant groups on timelines
* geographical distribution: species on different continents developing similar traits due to the environment

evidence for evolution con.

* comparative anatomy: scientist compares the anatomy of organisms to look at the relations. For example, some have similar structure bodies or homologous structures. or vestigial structures(a structure that has a reduced function) like the human appendix.
* similarities in embryos
* comparative biochemistry or DNA
* adaptions: a trait that increases an organism’s chances of survival and reproduction, like mimicry or camouflage

mutation

a change in DNA, can be harmful, beneficial, or neutral

what is the ultimate source of new alleles?

mutations

diploidy

having double chromosomes, most organisms are a diploid

mechanisms for evolution

* gene flow: when organisms from one community migrate to another, this introduces new alleles to the gene pool
* nonrandom mating: organisms mate with people close to them, this can promote inbreeding and cause homozygous traits in many offspring
* bottleneck effect: a large portion of the population destroyed in a disaster

sympatric speciation

when a species evolves into a new species in an area without a geographic barrier

temporal isolation

when two or more species reproduce at different times

evolution

change of animals through natural selection

nature is constantly putting pressure on a species to…

get food, push DNA into the future, and not become something else’s prey