Descent with Modification PDF

Descent with Chapte Modification: r 22 A Darwinian View of Life Evolutionary Theory Theory What is a theory? Broad explanation that is supported by evidence Evolution Descent with modification Change over time in the genetic composition of a popul...

Descent with Chapte Modification: r 22 A Darwinian View of Life Evolutionary Theory Theory What is a theory? Broad explanation that is supported by evidence Evolution Descent with modification Change over time in the genetic composition of a population A pattern & a process Pattern: Quantifiable data; Facts observed in nature Process: Mechanisms that produce observed change The Road to Darwin Aristotle (384-322 BCE) Scala Naturae Carrolus Linnaeus (1707-1778) Binomial Nomenclature Ideas about change over time Fossils Remains or traces of organisms from the past Strata Layers of rock Paleontology Study of fossils Georges Cuvier Catastrophism  Ideas about Change over Time Geology Study of earth James Hutton (1726-1797) Gradual change of Earth’s features Charles Lyell (1797-1875) Uniformitarianism Uniform natural laws govern geologic processes and have since the beginning of planet  Jean Baptiste de Lamarck 1744-1829 1809 - Published his ideas Gradual evolutionary change Explained the fossil record Organisms adapt to their environment Proposed two principles  Lamarck's Principles 1. Use and disuse What is used grows, what is not deteriorates 2. Inheritance of acquired characteristics Organisms could pass on acquired modifications Wrong only about mechanism of transmission Recognized match of organisms to their environments could be explained by gradual change Charles Darwin (1809- 1882) Voyage of the Beagle  Galapagos Islands 972 km west of South America along equator Volcanic islands Unique diversity of endemic organisms Finches Observed on Galapagos Darwin’s Finches Descended from stray flock that arrived on the Galapagos Islands Little competition for various types of food Different beaks and behavior corresponded to food available on specific islands Example of adaptive radiation Adaptive Radiation Period of evolutionary change in which groups of organisms form many new species whose adaptations allow them to fill different ecological roles in their communities.  After HMS Beagle voyage 1844 – wrote long essay on origin of species and natural selection Not published Alfred Russell Wallace Developed similar ideas of natural selection in the Malay Archipelago Wallace and Darwin’s ideas presented Darwin’s book published in 1859 On the Origin of Species Darwin’s book published in 1859 2 main points 1.Descent with Modification 2.Natural selection and Adaptation  Descent with Modification Darwin’s phrase describing evolution Organisms are related through descent from common ancestor that lived in the past Darwin’s metaphor Tree with multiple branches from common trunk  Artificial Selection, Natural Selection, and Adaptation Artificial Selection Human modification of other species through selective breeding of individuals Natural Selection & Adaptation 1. More offspring are produced than can survive 2. Those that survive are “suited” to the environment Are successful at reproduction Pass genes for characteristics to offspring RESULT: Favorable adaptations for survival stay Unfavorable adaptations are lost  Natural Selection Process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates that others because of those traits. The unequal ability of individuals within a population to survive and reproduce Due to GENETIC VARIATION within the population Environment “selects” the better suited individuals to “survive” Genetic Variation in a Population Natural Selection Natural Selection Keys to Natural Selection More offspring are produced than can survive Those that survive are better suited to the environment Survivors have heritable traits that can be passed on to new generations Keys to Natural Selection Over many generations Produce organisms better adapted to particular environment Populations evolve Not individuals Evidences for Evolution  Evidences for Evolution 1. Observations of evolution A. Changes in the soapberry bug’s food source causes evolution through natural selection for shorter beak length. Rise of drug resistant pathogens Methicillin-resistant Staphylococcus aureus  Evidences for Evolution 2. Homology - Similarity in characteristics resulting from shared ancestry A. Homologous Structures Variations on a structural theme that was present in some common ancestor http://www.pbs.org/wgbh/nova/ evolution/guess-embryo.html Embryonic Homologous Structures  Evidences for Evolution 2. Homology - Similarity in characteristics resulting from shared ancestry A. Homologous Structures Variations on a structural theme that was present in some common ancestor B. Vestigial Structures Remnant features that served important functions in the organism’s ancestors. Vestigial Structures Evidences for Evolution 2. Homology, continued C. Molecular Homologies Similarities in DNA & protein molecules between related organisms More in common = more closely related organisms are  Evidences For Evolution Convergent Evolution Evidences For Evolution 3. The Fossil Record Fossilized remains of organisms that lived in the past Fossils confirm appearance of major groups in geologic history  Evidences For Evolution 4. Biogeography Geographic distribution of species Similarities of fossils found in recently separated landmasses