how does evolution happen ch.5, sec.2. charles darwin
TRANSCRIPT
How Does Evolution Happen
Ch.5, Sec.2
Charles Darwin
18311831Naturalist on HMS Naturalist on HMS BeagleBeagle
Collected Collected plant/animal plant/animal specimensspecimens
Traveled to Traveled to Galapagos IslandsGalapagos Islands
He noticed He noticed animals/plants on animals/plants on Galapagos similar but Galapagos similar but not identical to not identical to mainland speciesmainland species
Main species Main species observed were observed were finchesfinches
FinchesFinchesDifferent from Different from mainlandmainland
Different from Different from others on islandothers on island
Mainly shape of the Mainly shape of the beakbeak
QuestionQuestionWhy were the Why were the finches on the finches on the island similar, but island similar, but not identical to the not identical to the ones on the ones on the mainland?mainland?
Thomas MalthusThomas MalthusHumans have the Humans have the potential to potential to reproduce beyond reproduce beyond food suppliesfood supplies
Darwin noticed…Darwin noticed…Species produce Species produce more offspring than more offspring than can survivecan survive
Limited # survive Limited # survive and reproduceand reproduce
Why?Why? ADAPTED
Natural SelectionNatural SelectionProcess by Process by
which evolution which evolution may occurmay occur
STEPS OF STEPS OF NATURAL NATURAL
SELECTIONSELECTION
1) Overproduction1) OverproductionSpecies produce Species produce
more offspring than more offspring than will survivewill survive
Ex. - frogsEx. - frogs
2) Genetic Variation2) Genetic VariationIndividuals are Individuals are slightly diff. from slightly diff. from
each othereach otherSome are better Some are better
adaptedadapted
3) Struggle to Survive3) Struggle to SurviveCompetition for Competition for
resourcesresourcesSome better Some better
adapted to obtain adapted to obtain resourcesresources
4) Successful 4) Successful ReproductionReproduction
Well adapted Well adapted == survival survival ==
reproductionreproductionSpecies continuesSpecies continues