Descent nt with Modifica catio tion evolutionary change is based - PDF document

7/15/2016 What t is evolution on ? Descent nt with Modifica catio tion evolutionary change is based on the interactions Chapter er 22 between populations & their environment Darwini winian an Evolut utio ion which results in adaptations (inherited characteristics) to increase fitness Evoluti tion on change over time in the genetic composition of a population. Histori storical l Context of Evolu lution ion • Species are fixed (unchanging) Darwin was influenced by many scientists in developing his theory. • Life-forms arranged of scale (ladder) of increasing complexity ( scala naturae ) • Each life form had its permanent place on the ladder Aristotl tle • Follows Old Testament 384-322 B.C (creationism) • Founder of taxonomy/binomial Paleontologist – studied fossils nomenclature Domain – Kingdom – Phylum – Class – • Deeper strata (layers) - very Carol olus Linnaeu eus Order – Family - Genus – Species George e Cuvier ier different fossils from current life 1707-1778 (1769-1832) • Extinctions were common • Domains: Eubacteria, Archaea, Eukarya occurrences yet opposed idea of • Nested system: species grouped into evolution increasingly general categories • Classification based on anatomy & Catas astr troph phism sm : events morphology destroyed many living species in local areas, then area was • Grouped species by resemblances from pattern of their creation not evolutionary repopulated by immigrant Classified diversity for the relationships species “greater glory of God” 1

7/15/2016 Geology ology Jean Lamarck (1744-1829) 1801 Charles s Lyell James s Hutto ton 1. Theor ory y of desire 1797-1875 1726-1797 - organisms change due to inborn desire to change to Gradualism sm become more fit for environment • ex: ant eaters develop long snouts Uniform rmita tari rian anism sm • mechanisms of Gradualism sm: 2. Theor ory y of use and disuse use • change are slow and - organs that are being used get large and strong geologic change constant over time. - organs that are not used shrink and eventually disappear results from slow, ex: snakes- didn’t use legs so disappeared gradual, continuous Slow & subtle process still • 3. Theor ory y of inheritance ance operating today. changes in - acquired traits were passed on to offspring organisms lead to ex: snakes that lost legs passed trait big change Importan ance ce: Recognized that species evolve, although explanation was flawed Charl rles s Darwin (1809-1882) Malthusian sian Doctri rine • More babies born than deaths • Consequences of overproducing within environment: war, famine, disease Thomas as Malthus (1766-1834) • Struggle for existence Uniq ique specie ies • British naturalist • Proposed the idea of evolution by natural ral selecti tion • Collected clear evidence to support his ideas 2

7/15/2016 Darwin’s Finches Darwin’s conclusions • small populations of original South American finches reached islands • variation in beaks enabled some to obtain food successfully in the different environments • over many generations, the populations of finches changed anatomically & behaviorally • Beak variation: an example of adaptive radiation. • accumulation of advantageous traits • 14 species of finches: evolved from one common • emergence of different species ancestor in South America Other examples of adaptations to food source • Finches with beak differences that allowed them to… - successfully compete - successfully feed - successfully reproduce 1859: : Origin gin of the Specie ies Origin gin of the Specie ies • Darwin waited 30 years before he Darwin amassed evidence that descent with modification published his ideas on evolution by natural selection explains three broad observations about nature: • Alfred Russell Wallace – published paper on natural selection first (1858) • The unity of life: organisms share many characteristics • Charles Darwin (1859): On the • The diversity of life: organisms accumulate adaptations Origin of Species by Means of Natural Selection • The match between organisms and their environments Mechanism for evolution is Natural al Select ction on Darwin didn ’ t use “ evolution ” , but rather “ desc scent nt with modificat cation on ” 3

7/15/2016 Parts ts of Theory Darwin’s Theory of Natural Selection 1 . Overp rpro roducti tion - organisms produce more offspring than can survive - leads to competition Natura ral selecti tion Individuals that have physical or behavioral traits ts that better suit their r enviro ronment are more likely to survive and will reproduce more success ssfully than those without traits. 2. Genetic variat ation 3. Struggl gle to survive - individuals in a given species vary by chance - all organisms face constant struggle to survive (due to gene recombination) - normal (limited resources) . exception: identical twins 4. Survival al of the fittest st DIFFEREN ERENCE CE IN THEORI ORIES ES - Individuals best adapted to environment are more likely to survive and reproduce Lamarc arck: organisms change in order to survive in - Over time favorable traits increase in population environment Adaptations enhance an organism ’ s ability to survive and reproduce. - occurs in the organism’s lifetime Darwin: environment determines which organisms survive through natural selection Over long periods of time, steady input of new variations in a population lead to speciation. - occurs rs over many generat rations 4

7/15/2016 Evide dences s of Evolution ion 1. Direct Observa rvation ions 1. 1. Direct t Observ rvat ations Antibiotic Resistance: MRSA (methicillin-resistant Staphylococcus aureus) 2. Fossil record 3. Homology gy homologous & vestigial structures embryology molecular: protein & DNA sequence 4. Biogeo geograpy apy 2. Fossil record Soapberry bug beak length shortened in response to change in food source. • Most occur in layers of rock, with the youngest usually on top, and the oldest in deeper layers (sedimentary rock) • Some found in amber (fossilized tree sap) • Record incomplete due to soft outer coverings on organisms not leaving imprints • 99% of all species that lived on Earth are now extinct. 3. Homol ology gy (similari ariti ties s among organism sms) Transi siti tional al Species s (links to modern species) Tiktaalik roseae , a 375 million-year-old transitional Homolo ologou ous structures: : structures which developed from a common ancestor, but have changed over time due to species between fish and the first legged animals, different purposes (diver ergent evolu lution ion) reveals that the evolution of hind legs actually began as enhanced hind fins. 5

7/15/2016 Embryologic ryologic similari laritie ies Vestigia gial l organs/ structur tures es: • evidence of a common • Structures which have lost all or most of their ancestor original function in a species through evolution. • dorsal, hollow nerve cord, • Degenerated, atrophied, or rudimentary condition notochord (stiffening rod of cartilage) in the back • Evidence of change over time • similar membranes in the embryos, yolk sac that produces the first blood cells vestiges of pelvic girdle of eyes on nicitating membrane and germ cells leg bones of walking ancestors blind cave fish • similar development of many organs Evolu lution onary ry Trees Molecula lar/ r/ Biochemica ical homologi gies es • Closely related species (branches) • Homologous characteristics share same line of descent until their that are inherited from a divergence from a common ancestor common on ancest stor or are strong • DNA, RNA, amino acids, and serology (comparison of indications of evolutionary blood chemistry) relationships • For example, "Tetrapods" all Species Amino Acid Differences from Human possess four limbs, presumably Hemoglobin Protein because they evolved from an ancest stor or (#2) that had four 1 Gorilla limbs. 8 Rhesus monkey Pg 464 Mouse 27 Chicken 45 Frog 67 Lamprey 125 Convergen rgent t evolutio ion 4. Bioge geogr graphy • independent evolution of similar features in different lineages • Geographic distribution of a species • Distantly reated species resemble one another • Species in nearby geographic areas resemble each other Analog logou ous structures es: similar in appearance and function, but - Continenta tal drift and Pangae gaea explains different origins with different internal structures similarities on different continents - organisms with different ancestors become more alike - Endemic species: found at a certain geographic because they share same environment location and nowhere else diss ssimilar ar struct ctur ures s  more similar ar struct ctur ures ex: Marine iguanas in the Galapagos 6

7/15/2016 Natural ral Selection ion vs Artif ific icial ial Selection ion Island d Bioge geograph ography Natural Selectio ion Artif ificia ial l Selection Nature selects/decides Man selects/decides Acts on individual Selective breeding Population evolves over time Inbreeding occurs Occurs over long periods of time Occurs in short period of time 7