Presentation on theme: "EVOLUTION. EVOLUTION The first living organisms were simple, single celled organisms. Through time more complex simple- celled creatures were created."— Presentation transcript:
3 The first living organisms were simple, single celled organisms. Through time more complex simple- celled creatures were createdBillions of years increasingly complex, multicellular organisms began to appearThe idea that explains how this change in species has occurred over time is evolutionWhat is evolution?
4 The Evolution ManCharles Darwin was a person who first suggested the theory of evolutionTheory- a concept that has been tested and confirmed in many different ways and can be used by scientists to make predictions about the natural world
5 Charles Darwin Born February 12, 1809 Died April 19, 1882 English naturalistCollector and geologistProposed and provided scientific evidecne that all specias of life has evolved for time from common ancestors through the process called natural selectionNatural selection- evolution was contolled by nature rather than people
6 The Occurrence of Evolution Darwin believed:The mechanism of evolution was like the process of artificial selection practiced by breeders of plants and animalsBelieved in natural selectionIn natural selection individuals that survive are able to breed and pass their genetic information to the next generationThose who are not successful in their habitat will usually die without leaving any offspring
7 Outlook of EvolutionIn an environment,the individual born with a characteristic that gives it an advantage and adapts to its environment will most likely survive.If they do survive the favorable characteristics will be passed on to many of the offspringThe characteristics that reduce an individual’s chance of surviving will decrease over timeIf an individual does not have favorable characteristics it will eventually die off
8 Factors of Evolution Over Production In each generation a species has the potential to produce more offspring than can possibly surviveIf too many of the offspring survive, they would overrun the Earth, although this does not happenIn a stable environment the population stays the same fron one year to the nextThis happens because not all the individuals can surviveStruggle For SurvivalOverproduction= competitionThe offspring have to cope with environmental conditions or it will die outThey also need resources such as oxygen, food and shelter but they are very limited.Individuals best suited to the environment will survive and those not well suited to the environment will die off
9 Selection by Environment Factors Of EvolutionVariationThe new traits that can lead to evolution come from normal variations within species.Organisms within species are never exactly alikeIndividuals have different variations, some better suitable to survive than othersThis difference is due to genetic variationThe unique combination of traits each organism inherits from its parentsSelection by EnvironmentTraits with adaptive value in a specific environment give individuals in that environment a competitive advantage.If the beneficial trait is past on to the offspring, they will also be more likely to survive and reproduceThe proportion of individuals with the good characteristics will increase because they are better able to compete with individuals without beneficial trait.Later on nearly all of these individuals in the population will have the traitThis change in characteristics present in population over time is evolution
10 Interactions with Evolution There are many factors in evolutionOverpopulation= the potential for species to in crease its numbersThe limited supply of resources needed for lifeThe genetic variation of offspringThe selection by the environment of those offspring better able to survive and reproduceCompetition
11 Variations in Evolution The arrangement of an individuals DNA bases determines all the inherited characteristics of that individualIn sexual reproducing, only changes in the genes of sex cells can be passed on to the next generation and become basis for evolutionary changeMutation and genetic shuffling is a genetic variation
12 MUTATION Mutation is a change in the base sequence of a DNA molecule Mutations occur at random and can’t be predictedMutations occur by errors of DNA as cells function but radiation and some chemicals can cause mutationsWhen a mutation happens they affect only that individual ; although mutations in a single celled organism or in the sex cells of a multicellular organism can be passed on the the offspringUsually mutations are harmful and may affect the offspring so severely that it can not survive although some mutations are beneficial
13 Genetic ShufflingGenetic Shuffling- the sorting and random recombining of genes during meiosis and fertilization results in new and different combinations of genesThe genes can be passed on to individual offspringThis process is similar to shuffling a deck of cards = the deck stays the same but the order is somewhat differentAt fertilization even more variety is introduced because now cards from two decks are combinedAlthough mutations provide new genetic instructions, genetic shuffling is the main source of the variation that exist among the members of any sexually reproducing species
14 Why is variation important? The variation of an organism within a species increase the likelihood that at least some members of the species will survive in a changed environment.
15 Extinction Extinction Extinction is the disappearance of an entire speciesWhen the death rate of individuals within a species is greater than the birth rate, extinction is a possibilityUsually extinction happens when the environment changes. When an individual can not adapt to the environment changes they will die outFossil records show that throughout geologic time, millions of species have evolved survived for a while than died off finally becoming extinct.Extinction