Evidence for Evolution Chapter 22

Big Idea 1: The process of evolution drives the diversity and unity of life Enduring Understanding 1.A: Change in the genetic makeup of a population over time is evolution Essential knowledge 1.A.4: Biological evolution is supported by scientific evidence from many disciplines, including mathematics. Scientific evidence of biological evolution uses information from geographical, geological, physical, chemial and mathematical applications.

1.A.4 Molecular, morphological and genetic information of existing and extinct organisms add to our understanding of evolution. Fossils can be dated by a variety of methods that provide evidence for evolution. These include the age of the rocks where a fossil is found, the rate of decay of isotopes including carbon-14, the relationships within phylogenetic trees, and the mathematical alculations that take into account information from chemical properties and/or geographical data. X The details of these methods are beyond the scope of this course and the AP Exam Morphological homologies represent features shared by common ancestry. Vestigial structures are remnants of functional structures, which can be compared to fossils and provide evidence for evolution.

1.A.4.b Biochemical and genetic similarities, in particular DNA nucleotide and protein sequences, provide evidence for evolution and ancestry. Mathematical models and simulations can be used to illustrate and support evolutionary concepts. To foster student understanding of this concept, instructors can choose an illustrative example such as: Graphical analyses of allele frequencies in a population Analysis of sequence data sets Analysis of phylogenetic trees Construction of phylogenetic trees based on sequence data Learning Objectives: LO 1.11 The student is able to design a plan to answer scientific uestions regarding how organisms have changed over time using information from morphology, biochemistry and geology. [See SP 4.2] LO 1.12 The student is able to connect scientific evidence from many scientific disciplines to support the modern concept of evolution.

What you need to know! Several examples of evidence for evolution. The difference between structures that are homologous and those that are analogous, and how this relates to evolution. The role of adaptations, variation, time, reproductive success, and heritability in evolution.

Types of Evidence Evidence for evolution is provided by 4 scientific principles Direct observations The fossil record Homology Biogeography

Direct Observations Wild guppies w/ plain colors The common cold and flu Drug resistant bacteria and viruses Peter and Rosemary Grant’s work on finches Beak sizes changed from one generation to the next based on environmental factors Pesticide resistant insects

Fossil Record Paleontology is the study of fossils Fossils are remains or traces of life in sedimentary rock Substantial, but incomplete, chronicles of evolutionary history Transitional fossils have been found that link ancient organisms to modern species Coincides with biogeographical understanding (continental drift)

Fossil Record

Homology Def: traits in related species can have underlying similarity w/ different function Homologous Structures: structural similarity of body due to common ancestry functionally dissimilar

Homology Embryonic homologies are the notable anatomical similarities in the embryonic development of animals

Homology Vestigial Structures: anatomical structures that ancestors used but now have reduced (or no) function

Homology Molecular homology includes a variety of similarities: All organisms share the same genetic code (DNA/RNA triplets/codon) The closer related a species, the higher the percentage of identical DNA Chimp and human DNA is 98% identical Bird and Human DNA is only 60% identical Plant and Human DNA is only 10% identical

Homology Convergent Evolution: unrelated species around the world look similar when found in similar environments (analogous structures)

Biogeography Def: geographic distribution of species Species tend to be more related to nearby species i.e. desert animals in South America are more related to local animals in other habitats than to African desert species Continental drift explains the similarity of species on different continents Endemic species are species unique to one specific environment (marine iguanas)