410 likes | 642 Views
Natural Selection & Evolution. Change or evolve over time. Evolution. Evolution -the gradual change in the characteristics of a species over time . Charles Darwin is the founder of modern evolutionary theory. natural selection is how populations of organisms evolve (change).
E N D
Evolution • Evolution-the gradual change in the characteristics of a species over time.
Charles Darwin is the founder of modern evolutionary theory. • natural selectionis how populations of organisms evolve(change) Charles Darwin1809-1882 The Theory of Evolution
process by which individuals that are better suited to their environment survive and reproduce most successfully. • It is a mechanism of evolution. Natural Selection
Natural selection in a nutshell Birds and green beetles - Which color beetle has batter chance of survival? Which genetic trait do you think natural selection selects against?
Peppered moths were originally light colored • Pollution caused lichen trees to darken • Light colored moths were eaten • Natural selection favored dark moths (by 1895 , 98 % moths were black) Natural Selection :Peppered Moth
Organisms with less favorable variations(differences) are less likely to survive and pass on traits to the next generation.
Results of Natural Selection • - Speciation • - Diversity • - Extinction
Speciation- is the evolution of a new species. • Occurs only when either interbreeding or the production of fertile offspring (children) is prevented. Speciation
Diversity Variations (differences) are genetic: they are controlled by an organism’s genes
diversity variations: spread through a population as it produces offspring a NEW species may evolve over time from the existing species. - Evolution of an ancestral (old) species into an arrangement of species that occupy different niches is called adaptive radiation.
Extinction Triceratops Wooly mammoth
Extinction Thylacine dodo
Extinction- when the last member of a species dies. • Extinction is a natural event • each species must become adapted to a changing environment • Result: The best genetically adapted species will escape extinction or change through natural selection. Extinction
How do we know Evolution occurred? • 1. the fossil record of change in earlier species • 2.the chemical and anatomical similarities of related life forms • 3.the geographic distribution of related species • 4. the recorded genetic changes in living organisms over many generations
Fossil Record • Remains of animals and plants found in sedimentary rock deposits are a record of past changes through time. • It confirms that species are not fixed but can evolve into other species over time.
Chemical Similarities • There are tens of thousands of types of proteins in living organisms • yet they are made of only 20 kinds of amino acids. • Our genetic codes are nearly the same
3 billion letters A,G,C,T
Compared to a human being…. 96 % 60 % 88% 60%
90 % 79% 69 % 80 %
Anatomical Similarities • Same types of bone (humerus, radius, and ulna) : • Human arms • Wings of birds • Forelegs of cats and dogs
Why? because they have retained these traits of their shared common ancient vertebrate ancestor.
biogeography Biogeography is a branch of geography that studies the past and present distribution of the world's many species.
Phylogeny • Comparing present day life with the remains of ancient (old) life forms is an example of phylogeny (evolutionary history) of a species