Darwin s Influences Charles Lyell Geological forces change the earth s surface Uniformitarianism mechanisms change over time He proposed that the same geological processes from the past are operating today and at the same rate Jean Baptiste de Lamarck Organisms change overtime and become more highly adapted to their environment Inherited characteristics o Explanation gone wrong o Use and disuse If you use it it will grow If you don t you lose it o Inheritance of acquired characteristics If you dyed you hair blue the kids will have blue hair o Also believed that organisms have an innate drive to become more complex George Cuvier Paleontologist Advocated catastrophism a principle that events in the past occurred suddenly and were caused by mechanisms different from those operating in the present Fossils show the change in species over time o Missing and or new layers appearing in fossils Catastrophism Theory Things disappeared and new stuff reappears in its place Fossils are remains or traces of organisms from the past Strata are the layers within a sedimentary rock o Thomas Malthus Economist The youngest stratum is the uppermost layer of the fossil Over population of people causing human suffering disease famine and war Darwin Evolution First Piece Variation Second Reproduction Malthus Natural Selection Third Piece Adaptation Lamarck Fourth Piece Darwin s Finches Saw genetic variations and adaptations of the dead finches he caught in the island Thought that all the finches came from a common ancestor and when a erupted volcano created the Galapagos islands the finches probably diversified Evolution descent with modification It means that species now are different progenies of ancestral species Voyage of the Beagle Primary mission chart poorly known stretches of the S American coastline Darwin realized that animals on the Galapagos looked like animals on the S American mainland and most Galapagos species were not known to be anywhere else o He hypothesized that the Galapagos islands were colonized by animals that strayed from the mainland and diversified creating new species Natural Selection is the process in which individuals that 1 have certain inherited traits tend to survive and 2 reproduce at higher rates Heritable Traits Survive and Produce Adaptive Adaptions o Adaptations are inherited characteristics of organisms that enhance their survival and o reproduction in specific environments The dead finches Darwin was analyzing had various beaks due to the specific food sources that were available in that area Speciation how a species comes to be Populations evolution occurs at the population level changing gene frequency of time Variations if an environment changes then natural selection may result in adaptation giving rise to new species Artificial Selection is when humans modify other species by selecting and breeding individuals with the desired traits we want to achieve Direct Observation Soapberry bug o Has a beak Crops Stock animals Pets Projection beak that allows it to get food long or short A different food source can change the species Homology Structural themes Is similarity resulting from common ancestry not necessarily the same functionality o Examples o Arms fins and wings have a common ancestor Analogy Similarity in function not ancestry Examples o Gills and lungs gas exchange Sugar glider v Flying squirrel o You can be both homologous and analogous Comparative embryology reveals anatomical homologies not visible in adult organisms Allows us to see the resemblance of what was their common ancestor Some people were born with tails and gills Appendix helps break down cellulose Vestigial Structures remnants of features important to ancestral species Webbing between fingers Wisdom teeth Homology at the molecular level genes shared among organisms inherited from a common ancestor Homologies and Tree Thinking Moss fern fur tree evergreen magnolia trees maple rose corn Word of caution similarities do not necessarily mean relatedness Convergent evolution evolution of analogous features in distantly related groups due to similar environments Evolutionary Trees hypothesis about relationships among different groups see 22 17 Reason why you might get similar looking creature such as fish and whales living in water having streamline shapes Sugar glider and flying squirrels look the same Provides evidence of o Cuvier The extinction of species The origin of new groups o Transitions Titolgic fish tetrapod Changes within groups over time o Fossil Record Biogeography Continent movement Is the geographic distribution of species Pangaea separated by continental drift It can predict when and where different groups evolved when we understand o o Modern distribution of species Endemic species o Not found anywhere else in the world o Islands and mainland Mainly places that are isolated What is theoretical about Darwin s view of life Evolution by natural selection o o Common thread in all of biology Stimulates many new research questions Darwin proposed that individuals within a population varied in traits What do we know can cause this variation Copying errors during DNA replication Random fertilization Independent assortment during meiosis Crossing over during meiosis 1 2 3 4 5 Mutations in genetic code 6 Natural selection Can natural selection work on a population that is not genetically variable A Yes B No The Smallest Unit of Evolution Natural selection happens among individuals but populations evolve Microevolution Four mechanism that cause allele frequency change o Natural selection change in allele frequencies in a population over generations Only one that causes adaptive evolution o Genetic drift o Gene flow o Mutation Genetic variation makes evolution possible Variation makes evolution possible o o o Natural selection will only work on the genetic component Evolution requires variation in heritable traits Phenotype genotype environmental influences Variation Within a Population either or basis Discrete v Quantitative o Discrete o Quantitative Genetic variation variation in genes or nucleotides o Genes average heterozygosis average of loci that are heterozygous in a population o Nucleotides measured by comparing the DNA sequences of pairs of individuals vary along a continuum New genes and alleles can arise by mutation or gene duplication o Mutation in gametes can be passed to offspring rarely beneficial more likely neutral or harmful o Duplicated genes can take on new