In This Course How did life on earth become the way It Is today? What differences exist among living organisms? What drives bloodlessly? How are structures related to function? Life: The Why and the How Ultimate vs.. Proximate questions: Ultimate: Why? Why are we here? Why does life exist? Proximate: How? How did we get here? How did life become what It Is today? Philosophy and religion?ultimate questions Science?proximate questions, few ultimate Evolution Many ways to define
Descent with Modification?modern descendants are different from ancestors Change in genetic makeup off populations Early Ideas About (384 – 322 BCC) Species are fixed, unchanging Scale nature?”ladder” of life, from least to most complex Matches well with creationism/ Intelligent design?living thing were created perfect and match their environment perfectly Linnaeus’ View 1707-1778, Swedish, physician/ botanist Classify diversity of life to discover God’s plan Binomial nomenclature?method of naming organisms Genus and species Ex. Homo sapiens, Tyrannosaurus rexes Sometimes name tells something about it, sometimes a person
Similar species grouped together no based on relatedness, but “creativeness” Charles Darwin Born In Shrubbery, England 1809 Interested in nature all his life Fatter sent NV to meal cocoons Found it boring and horrifying Enrolled at Cambridge to become clergyman After graduating, went on Beagle to survey South America Influence on Darwin: Fossils Paleontology?study of fossils Georges Quiver (1769 – 1832) saw that older fossils were less similar to extant (existing) species Extinctions common Opposed evolution Proposed catastrophic: boundaries due to local catastrophes Influences on Darwin: Geology James Hutting (1726 – 1797)
Geologic features we see today are due to long, slow process of erosion Charles Lye (1797 – 1875) Unfamiliarity’s: mechanisms of change are constant over time Forces in past same as today Theses ideas of slow, continuous change strongly influenced Darwin Darning’s voyage on The Beagle Started December 1831 (Darwin was 22) Darwin spent most of his time observing and collecting plants and animals Noted characteristics that made them well-adapted to where they lived Also noted they were more similar to each other than ones found in similar habitats overseas The Galapagos Some animals looked like ones on mainland, but different
Others were similar to each other, but with unique traits Darning’s finches Colonization and isolation? Idea of adaptation Adaptations Adaptations?inherited characteristics that enhance survival and reproduction Can gradual accumulation of adaptations lead to new species? Origins of The Origin Darwin was afraid to publish his ideas Public outcry? Advised to Just go ahead and publish them before someone else did… Russell Wallace Darwin vs.. Wallace Wallace sent Darwin his manuscript on natural selection Like Alfred very salary to Darning’s Darwin hurried and finished The Origin of Species Wallace admired Darwin, said he
The Origin of Species “Evolution” never used in first edition Focused on descent with modification All modern life came from ancient ancestor As its descendants lived in different habitats, they accumulated adaptation 0 new species History of life is like a Natural Selection One of several processes that drive evolution “Survival of the fittest” Two Key Components: Members of a population vary in their inherited traits All species can “over-populate/ reproduce,” but only a few individuals survive and reproduce Most survive long enough to reproduce Short vs.. Long-lived strategies? Examples of Natural Selection What helps survival?
Defending itself Things that help them in their environment What helps reproduction? Attracting it to something Artificial Selection Like natural selection, except the selecting agent is us Dog breeds Crops Important Note: Natural selection acts on individuals Individuals do not evolve, populations evolve Natural selection only works if a trait is both heritable and variable If heritable but identical, no natural selection Evidence for Evolution How can someone prove evolution is real? Homologous structures Vestigial traits Fossils Direct assertion Biography Evidence: Homologous Structures Developmental, physiological, molecular
Structures that derive from common ancestry But may have different functions now! DNA, etc. Sequences New way to construct trees Warning: Analogous Structures Structures that have same function, and may appear similar NOT due to common ancestry Insect and bird wings Eyes in vertebrates and eyes in squids Evidence: Vestigial Traits Traits that were used in the past, but no longer serve a function Examples? Appendix Wisdom teeth Flightless birds Eyeless cave animals Evidence: Fossils Similarity between extinct and extant species “Missing links” Evidence: Direct Observation Best source of evidence Artificial selection speeds up process
Examples of Observed Evolution: MRS. Nonmetallic?resists S. Erasures Staphylococcus Erasures Certain strains become “fleshing-eating” Became resistant to antibiotics over time How? Heritable variability in cell wall protein?Natural Selection “99. 99%” Evidence: Biography Geographic distribution of species Continental drift Pangaea?single large continent 250 million years ago Prediction of fossil locations Explains why islands have lots of endemics?found nowhere else Ex. Australia No placental mammals Has lots AT marsupials Explanation?