Darwinian Descent with Modification

Evolution Evolution: Natural selection: Evolutionary adaptations: the change over time of the genetic composition of populations Natural selection: populations of organisms can change over the generations if individuals having certain heritable traits leave more offspring than others (differential reproductive success) Evolutionary adaptations: a prevalence of inherited characteristics that enhance organisms’ survival and reproduction

Evolutionary history Linnaeus: taxonomy Lyell: uniformitarianism Hutton: gradualism Lamarck: evolution Malthus: populations Cuvier: paleontology Lyell: uniformitarianism Darwin: evolution Mendel: inheritance Wallace: evolution

Fossils and Acquired Traits Georges Cuvier (1769-1832) Palentologist Older fossils found in deeper layers of rock Catastrophism- each strata of rock represents a “catastrophe” in history Jean-Baptiste de Lamarck (1744-1829) First theory of evolution using fossil record Organisms pass on “acquired traits”

Darwin’s Voyage Darwin took a 5-year voyage on the HMS Beagle (1831-1836) Studied species and fossils in South America Fascinated by unique species on the Galapagos Islands

Variation Among Species

The Origin of Species Darwin wrote an essay on his observations in 1844 He feared controversy, so he didn’t publish it Similar theory written by Alfred Russel Wallace in 1858 Darwin compiled his observations and published The Origin of Species in 1859 2 Major Theories: Descent with Modification Natural Selection/Adaptation November 24, 1859

Descent with Modification Modern organisms have evolved from common ancestors 99% of all species that ever lived are now extinct

Natural Selection 3 Inferences: 5 observations: Struggle for existence Non-random survival Natural selection (differential success in reproduction) 5 observations: Exponential fertility Stable population size Limited resources Individuals vary Heritable variation

Artificial Selection Selective breeding of plants and animals Can create drastic changes over only a few generations

Natural Selection Overview Species vary; the more fit ones survive to reproduce Over time, organisms increase their adaptation to their environment If conditions change, species will often change to be better suited

Examples of Natural Selection Guppy size determined by predators present Evolution of HIV Drug resistance (those that are resistant survive and continue to reproduce)

Evolution evidence: Comparative Anatomy Homologous structures (homology) Descent from a common ancestor Vestigial organs Whale pelvis Snake hindlimbs Wings on flightless birds

Evolution evidence: Comparative Embryology All Vertebrates show similarities in embryology Pharyngeal pouches (gills) Post-anal tail

Evolution evidence: Molecular Biology Similarities in DNA, proteins, genes, and gene products Common genetic code

Evolution evidence: Biogeography Geographical distribution of species Examples: Islands vs. Mainland Australia Similar species on different Continents

Evolution evidence: The Fossil Record Succession of forms over time Transitional links Vertebrate descent