Theories of Evolution

An explanation for how something that takes into account known scientific evidence and can be modified according to newly found evidence and data.

A law is a description of patterns of what always happens and usually occurs in physics.

• before the 18th century people strongly believed that organisms were made one way at creation and remained the same until now

• Buffon: said he thought species could change and those changes could lead to new species • Linnaeus: thought there were a few species of creation who became hybrids which formed in species later (invented binomial nomenclature) • Erasmus Darwin: (Charles’ grandfather) believed that all life came from a single source

• first theory that involved a mechanism (a system of how something happens), the mechanism was the inheritance of acquired traits • believed in spontaneous generation • thought an organisms force of desire will create a trait to fulfill that desire within their lifetime and the use or disuse of that trait determined weather or not it would be passed on to its offspring • example: giraffes got a long neck because they had a desire to reach the food higher up on trees so they grew their necks in their lifetime and the use of the long neck determined that it would be passed on

• took a trip around the world on HMS beagle and observed the following • unusual fossils resembling giant sloths and armadillos that lived in the same region • from this he determined that life forms descended from fossils • species in South American tropics didn’t represent those in African tropics • from this it was concluded that species evolve independently if isolated

• the Galapagos islands has 13 species of similar finches that are found nowhere else but resembled a species living off the coast of South America • evolution from a single species in South America that arrived to Galapagos and evolved to be different from the original species because of a different habitat • he found fossil deposits of coral at an elevation of 3000m in the Andes • severe earthquake lifted portions of the East coast 3m upwards • geological forces responsible for location of fossils and mountains

• continued to gather evidence, perform investigations, and convene with other biologists • interest in artificial selection, recognized that all species possessed inherited variations that could be selected for • reasoned that if people could artificially select for traits than the environment could have the same affect on species • malthus: a math paper that said that all species produced more offspring than could survive • Darwin recognized that if so many offspring were being born they would have to compete against each other for survival • Wallace: a naturalist working in Malaysia who came up with the same findings independently then sent a letter to Darwin • colleagues convinced Darwin to publish a paper on his findings with Wallace’s paper

1) observation: individuals within a species exhibit many inherited variations 1) inference: individuals of the same species are in a constant state of struggle for survival 2) observation: every generation produces more offspring than can survive to reproduce 2) inference: individuals with more favorable variations are more likely to live on to reproduce to pass on its advantageous variations. Survival is not random it is determined through natural selection 3) populations of a species tend to remain stable in size 3) since individuals with more favorable variations contribute proportionally to succeeding generations their favorable traits become more common and this is evolution

5 distinct areas 1) overproduction: more offspring produced than can survive, reproduce and live to maturity 2) competition: organisms must compete for food, habitat, water, and shelter 3) variation: differences in species that are passed on to their offspring 4) survival of the fittest (natural selection): individuals that are well adapted to their environment are more able to compete, survive, and reproduce 5) origin of new species by inheritance of successful variations: over generations, new species arise through inherited genes; a new species is produced

Light colored moth called (typica) were prominent before the industrial revolution when their white speckled wings blended in with the white birch trees. Post industrial revolution the trees turned black because of pollution which led to a new type of moth (carbonaria). They had dark wings that were selected for because they blended in with the dark trees so they became prominent as the white ones died out. Bernard Kettlewell conducted a capture and release experiment where there were different moths in the black woods of Birmingham and the white woods of Dorset. When he captured he marked the bottoms of their wings with cellulose paint and the survival was proportionate to camouflage efficiency. His experiment was under criticism but his findings were generally accepted.

Originally it was mostly short necked giraffes existed but some variation still existed. As fruit on the shorter trees dwindled the giraffes with a variation with longer necks could reach the trees up high and they were more likely to survive.

fitness is referring to a level of reproductive success. - example: only giraffes with a adapted longer neck could survive and reproduce, over time the population of giraffes changed because that adaptation was passed on

• even though Darwin new variation existed he didn’t know where it came from • it wasn’t until the 1930s that enough information was gathered to understand genes hereditary • variation comes from mutations and sexual reproduction

• mutations are changes in a DNA segments genes • DNA: deoxyribonucleic acid and is a heriditary material that is passed on • genes: segments of DNA • DNA is in chromosomes of cells • composed of four nucleotide bases, ATGC • nucleotide bases together for a protein and are called codons • genes code for certain inherited traits • mutations are random changes in DNA sequence • insertion, deletion, substitution, and chromosomal re arrangements (duplication, inversion, and deletion) • these changes may or may not affect the function or expression of a gene • they provide a continuous supply of information

• experimental factors • errors in DNA production and replication • relatively rare in individuals because there is only one set of gametes, ones mutation per sex cell • mutagens have a higher rate of mutation

• Mutation in the Myostatin MSTN gene causes continuous growth and strengthening

1) neutral mutations (most common) 2) harmful mutations (more common than beneficial ones) 4) beneficial mutations - the environment determines which mutation is selected for, beneficial mutations are selected for and lead to adaptations

• accumulation of traits which improve a species ability to survive • its mechanism is natural selection 1) structural: modification of structures that allowed special functions • example: fingers, bat wings, leaves of pitcher plants 2) physiological: the change in the chemicals an organism produces • example: venom, digestive enzymes in the leaves of a pitcher plant 3) behavioral: actions and instincts of an organism • example: hibernation, migration

• mutations don’t occur as needed, they are random with harmful being more common than beneficial • since harmful mutations are more common they can cause extinction, this is false because beneficial mutations are selected for by the environment and favors an organisms fitness • evolution isn’t pure chance, beneficial mutations are selected for and can accumulate, beneficial mutations give individuals improved survival and enhanced reproductive fitness

1) asexual reproduction - less chance for variability because there is only one parent - reproduce through mitosis and binary fission - only inherit genes from that parent 2) sexual reproduction - inherit two sets of gametes so more chance for variability - enhanced mutation - production of offspring by the union of sex cells (gametes) from two different parents - gametes: sex cells - sematic cells: not sex cells

1) two copies of each gene one from each parent and they make different combos 2) assortment of genes an offspring inherits from either parent is random, the greater number of genes, the more combos, the greater variability 3) sexually reproducing species chose different mates, combos of parents means a different combo of genes

1) inherited characteristics: determined by genes, organisms possess thousands of genes 2) population variability: there’s variability within a population 3) source of new variation: new traits when genes are mutated 4) natural selection: genes determine traits that enhance an individuals chance of survival, and they will produce more offspring with the same advantageous gene 5) evolutionary change: over many generations, individuals carry genes that determine the most favorable traits for survival, these genes become more common in the population

• used to determine the choosing of a mate • is affected by traits that lead to adaptation which can result in reproductive isolation then speciation • example: necking fights, plumage of birds in the galapagos • the expenditure of energy to upkeep courtship rituals is indicator of the ability to get food and survive so those beneficial traits are passed on