Evolutionary Adaptations of the Blue-Footed Booby in the Galápagos Islands

1. 0 Chapter 13 How Populations Evolve

2. 0 Clown, Fool, or Simply Well Adapted? • The blue-footed booby • a type of bird living in the Galápagos Islands • Excellent example of evolutionary adaptations

3. 0 Evolutionary adaptations • Which are inherited traits that enhance its ability to survive and reproduce in its particular environment • Big webbed feet • Streamlined body • Large tail • Nostrils that close • Specialized oil glands • Specialized salt glands • Often adaptations are trade-offs • Ex Big feet good for swimming, but clumsy on land

4. 0 DARWIN’S THEORY OF EVOLUTION • 13.1 A sea voyage helped Darwin frame his theory of evolution • On his visit to the Galápagos Islands • Charles Darwin observed many unique organisms

5. 0 • What were Darwin’s Main ideas anyway??? • Species change over time • Living species have arisen from earlier life forms (descending from a common ancestor) * Close ties between organisms and their environments* • Darwin’s main ideas • Can be traced back to the ancient Greeks • Aristotle and the Judeo-Christian culture • Believed that species are fixed

6. 0 • In the century prior to Darwin • The study of fossils suggested that life forms change • Others were developing ideas: • Buffon- proposed fossils may be ancient versions of similar living species • Lamark- “big mistake” but was instrumental in early concept of evolution, before Darwin • Geologists proposed that a very old Earth • Is changed by gradual processes • Much older than 6,000 years

9. 0 NorthAmerica GreatBritain Europe Asia ATLANTICOCEAN PACIFICOCEAN Africa PACIFICOCEAN Equator TheGalápagosIslands PACIFICOCEAN SouthAmerica Pinta Genovesa Australia Marchena Equator Andes Cape ofGood Hope Santiago DaphneIslands Pinzón Fernandina Tasmania NewZealand Cape Horn Isabela SantaCruz SantaFe SanCristobal Tierra del Fuego 40 km 0 Florenza Española 40 miles 0 • While on the voyage of the HMS Beagle in the 1830s • Charles Darwin observed similarities between living and fossil organisms and the diversity of life on the Galápagos Islands

10. Evolution is the greatest unifying theme in biology, and The Origin of Species fueled an explosion in biological research and knowledge that continues today. Evolutionary theory continues to expand beyond Darwin’s basic ideas. Nonetheless, few contributions in all of science have explained so much, withstood as much repeated testing over the years, and stimulated as much other research as those of Darwin.

11. 0 • 13.2 Darwin proposed natural selection as the mechanism of evolution • Darwin observed that organisms • Produce more offspring than the environment can support (economist, Malthus) • Individuals of a population vary in their characteristics • Many characteristics can be inherited

12. Survival in a limited environment depends on the features the organisms inherit from their parents • Within a varied population, individuals whose characteristics adapt them best to the environment are most likely to survive and reproduce • Natural selection results in favored traits being represented more and more and unfavored ones less and less in ensuing generations of organisms

13. Hundreds to thousands of years of breeding (artificial selection) Ancestral dog (wolf) 0 • Darwin found convincing evidence for his ideas in the results of artificial selection • With humans playing the role of the environment

14. Evidence of Evolution • Fossil Evidence • Biogeography • Comparative Anatomy • Comparative embryology • Molecular biology • In vitro/ In field observations

15. A Skull of Homoerectus B Petrified tree C Ammonite casts D Dinosaur tracks E Fossilized organicmatter of a leaf G “Ice Man” F Insect in amber 0 • 13.3 The study of fossils provides strong evidence for evolution • Fossils and the fossil record strongly support the theory of evolution

16. 0 • The fossil record -reveals that organisms have evolved in a historical sequence • Strata reveal changes in organisms through time • Transitional Forms- • Intermediate species between ancient organisms and their modern day equivalents • Therapsids • Archaeopteryx

17. 0 • Many fossils link early extinct species with species living today

18. Oldest fossils- 3.5mya • Prokaryotes • Various eukaryotes • Vertebrate Evolution: • Fish • Amphibians • Reptiles • Mammals • Birds

19. 0 • Biogeography • Biogeography- the geographic distribution of species • Suggested to Darwin that organisms evolve from common ancestors • Break up of pangea • Darwin noted that Galápagos animals • Resembled species of the South American mainland more than animals on similar but distant islands

21. Cat Whale Bat Human 0 • Comparative anatomy- • Evolution is a remodeling process • Is the comparison of body structures in different species • Anatomical similarities in many species give signs of common descent • Homology- the similarity in characteristics that result from common ancestry • Homologous Structures- features that often have different functions but are structurally similar because of common ancestry • Vestigial Structures- structures of marginal if any importance to the organism

22. 0 Pharyngealpouches Post-analtail Human embryo Chick embryo 0 • Comparative Embryology • Is the comparison of early stages of development among different organisms • Many vertebrates have common embryonic structures • Pharyngeal pouches- gills in fish, ears/throat in humans

23. 0 • Molecular Biology Comparisons of DNA and amino acid sequences between different organisms reveal evolutionary relationships • Anatomical homology isn’t helpful linking distantly related organism (plants to animals) • Strong evidence for Darwin’s boldest claim: All Life Forms are Related • All forms of life use DNA and RNA with an essentially universal genetic code • Passed along through the branches of evolution

24. A flower mantidin Malaysia A leaf mantid in Costa Rica 0 • 13.5 Scientists can observe natural selection in action • Camouflage adaptations that evolved in different environments are examples of the results of natural selection Madagascan comet orchid Xanthopan morganii praedicta

26. Chromosome with geneconferring resistanceto pesticide Pesticide application Survivor Additionalapplications of thesame pesticide willbe less effective, andthe frequency ofresistant insects inthe populationwill grow 0 • Development of pesticide resistance in insects and antibiotic resistant bacteria

27. 0 • 13.9 In addition to natural selection, genetic drift and gene flow can contribute to evolution • Genetic drift • Is a change in the gene pool of a population due to chance • Can alter allele frequencies in a population • Has greatest impact on small populations • Bottleneck Effect • Founder Effect

28. Originalpopulation Bottleneckevent Survivingpopulation 0 • Bottleneck Effect: is an event that drastically reduces population size • Earthquakes, floods, fires • Produces a small surviving population that is unlikely to have the same genetic makeup as the original • Northern elephant seals in California- greatly decreased the species’ genetic variation

29. Founder Effect: colonization of a new location by a small number of individuals • The smaller the group- the less likely the genetic makeup of the founders will represent the gene pool of the population they left • Darwin’s finches and human Colonists

30. 0 • Gene flow is the movement of individuals or gametes between populations • When fertile individuals move into or out of a population • Or when gametes (pollen) are transferred between populations • Can alter allele frequencies in a population • Reduce differences between populations

31. 0 • Natural selection • Leads to differential reproductive success in a population • Individuals with characteristics that best match them to their environment have the most reproductive success

32. Natural Selection • Can alter allele frequencies in a population • Results in accumulation and maintenance of traits that adapt a population it’s environment • The degree of adaptation is limited by the amount and kind of genetic variation in a population

33. 0 • 13.10 Endangered species often have reduced variation • Low genetic variability -may reduce the capacity of endangered species to survive as humans continue to alter the environment • Ex) cheetah- decreased genetic variation due to bottleneck events during the last ice age • Human over hunting and encroachment/ breeding programs • Leads to fewer opportunities for natural selection to lead to traits best fit for changing environment

34. 0 VARIATION AND NATURAL SELECTION • 13.11 Variation is extensive in most populations • VARIATION WITHIN POPULATIONS • Just like we do as humans: anatomical as well as molecular variation • Genetics sources as well as environmental • Many populations exhibit polymorphism (many morphs)- different forms of a phenotypic character- can relate to behavior

35. 0 • VARIATION AMONG POPULATIONS • Populations may also exhibit geographic variation- • Variation of an inherited characteristic along a geographic continuum • As environments differ along a geographic continuum, natural selection will yield changes in individual phenotypes • Can occur in a cline- a graded change in inherited characteristics • Ex) Farter away from equator = larger body size

37. 0 • 13.12 Mutation and sexual recombination generate variation • Mutations- changes in the nucleotide sequence of DNA • Nucleotide substitutions • Chromosomal mutations • Can create new alleles when they occur in gametes • Not in somatic cells • Most are of no effect, Few are deleterious or have a negative effect , very, very few are positive • Rate of mutation varies • Bacteria- quick • Plants and animals- slowly (1 in every 100,000 genes per generation) • Plants and animals depend more so on sexual recombination to introduce variation

38. Parents A1 A1 A2 A3 X Meiosis Gametes A2 A1 A3 Fertilization Offspring,with newcombinationsof alleles A2 A1 A1 A3 and 0 • Sexual recombination • Generates variation by shuffling alleles during meiosis

39. 0 • 13.16 Natural selection can alter variation in a population in three ways • Stabilizing selection • Favors intermediate phenotypes • Directional selection • Acts against individuals at one of the phenotypic extremes • Disruptive selection • Favors individuals at both extremes of the phenotypic range

40. Originalpopulation Frequency of individuals Phenotypes (fur color) Originalpopulation Evolvedpopulation Stabilizing selection Disruptive selection Directional selection 0

41. 0 • 13.17 Sexual selection may produce sexual dimorphism • Sexual selection leads to the evolution of secondary sexual characteristics- sexual dimorphism • Which may give individuals an advantage in mating • Intrasexual Selection- contests • Intersexual Selection- mate choice

42. 0 • 13.18 Natural selection cannot fashion perfect organisms • There are at least four reasons why natural selection cannot produce perfection • Organisms are limited by historical constraints • Adaptations are often compromises • Chance and natural selection interact • Selection can only edit existing variations

43. The process of evolution requires the introduction and assortment of variation at genetic, individual and population levels Introduce VariationSort Variation gene Individual population mutation genetic recombination gene expression gene flow Selection (predictable) Genetic Drift (random)