ANTHRBIO 201 1st EditionExam # 1 Study Guide Lectures: 1 – 13Natural selection and other forces of evolutionWhat is the evidence for evolution? -fossils-similarities between related organisms-direct observations and small scale changes in the natural world produced by artificial selectionand long term changes in fossil recordDefine Evolution-Process where different living organisms diversify and develop throughout historyMutation-ultimate source of genetic variability -causes loss of existing alleles -changes gene frequencies at a slow rate-defined as a spontaneous change in the chemical structure of DNAMigration (Gene Flow)-movement of genes from one population to another -maintains similarities across populations-can produce large changes in gene frequencies over time- only takes 1Genetic Drif-caused by random effects of sampling variation in small populations -occurs during genetic transmissions in small population-more rapid in small populations than large ones -leads to unpredictable changes in gene frequenciesNatural Selection -produces adaptation based on:availability of resources is limited organisms vary in the ability to survive and reproduce traits that influence survival and reproduction are transmitted from parents to offspring Stabilizing natural selection and directional natural selection -directional: one extreme phenotype is favored-stabilizing: genetic diversity decreases, population mean stabilizes, favors intermediate variantsMicro and Macro Evolution-Micro: 4 processes (genetic drif, natural selection, mutation, migration) -Macro: how new species are created, changes on the molecular levelallopatric speciationa population is divided by some type of geographic barrier and different parts of the population adapt to their respective environments AdaptationA feature of an organism created by natural selectionGeneticsThe Modern Synthesis-Phenotypic expression is controlled by a set of genes with multiple loci -Bell shaped distribution of height and beak depth etc.-Genotypes affect phenotypesWhy is variation important for natural selection?-allows certain species to become better fit for environmental factors like the weather and the environment → survival of the fittestHow is variation maintained? -mutation adds new variation-hidden variation is shuffled through sexual reproductionBlending inheritance-results in intermediate forms that you will need to induce small changes for natural selection over time-widely accepted in 19th century-hereditary material of the mother and father was thought to combine irreversibly in the offspringParticulate inheritance-characteristics can be passed on without being expressedGene-a segment of the chromosome that produces a recognizable effect on phenotype and segregates as a unit during gamete formationAllele-one of a number of alternative forms for the same gene -dominant or recessiveMeiosis and the chromosomal basis of inheritance-only half of the chromosomes are transmitted from the parent cell to the gamete -gametes contain only one copy of each chromosome → haploid-genes reside on chromosomesMendel’s laws of segregation-law of segregation: 2 copies of each hereditary factor segregate so offspring acquire one from each parent-law of independent assortment: each of the genes at a single locus on a pair of homologous chromosomes is equally likely to be transmitted when gametes are formed-law of dominancehomo/heterozygous-homo: a diploid organism where chromosomes carry two copies of the same allele at a single genetic locus-hetero: diploid organism whose cells carry two different alleles for a particular locusgeno vs phenotype-geno: combination of genes/alleles an individual carries like AA, Aa or aa -pheno: observable characteristic like brown or blue eyeslinkage-tendency of alleles that are located close together to be inherited together during meiosis -reduces rate of recombinationcrossing over-when chromosomes frequently tangle and break as they are replicated during meiosisstability and replicability of DNA-replicability insures inheritance; 2 strands unravel and bond with new ones that are exact replicas-stability preserves genetic message;DNA bases, codons, amino acids and proteins -bases: Adenine Guanine Cytosine and Thymine-codons=3 letter DNA base sequence, creates specific protein -amino acids: 20 different ones, linked in a chain to form proteins -proteins: enzyme catalystsHardy Weinberg Equation-calculate the genetic variation of a population at equilibriumSpeciationBiological species concepts-groups of potentially or actually interbreeding organisms that are reproductively isolated from others to create barrier-gene flow homogenizes populations-idea that places a premium on reproductive isolationEcological species concepts-groups of organisms created and maintained through the process of natural selection -selectionmaintains species boundaries despite gene flowAllopatric speciation-geographic isolation between two or more population of a single species leads them to diverge and form new species that are reproductively isolatedSympatric speciation-strong selection that favors different phenotypes leads to speciation in the absence of geographic isolationCharacter displacement-a process that causes members of 2 species to diverge from each other due to the effects of competition-result of competition between two species that causes the members of different species to become morphologically/behaviorally more different from each otherNiche-total range of conditions under which the population lives and reproduces -way of life/trade of a particular speciesAdaptive radiation-process where a single species diversifies to fill several open niches -finches became seed eaters, cactus eaters etc.Reconstructing phylogeniesTaxonomy-basis for classifying organismsAncestral traits-presence of a tail, 5 fingers, forward eyes -appears earlier in the evolution of a lineage or cladeDerived traits -appears late in lineage -absence of a tail-humans are bipedalHomologous traits-share a trait due to common ancestry -all vertebrate animals have skeletonsanalogous traits-traits are similar but no because of relatedness -animals with wingsevolutionary convergence-independently evolve similar traits as a result of having to adapt to similar environments or ecological nichesmolecular clock-permits timing speciation events-genetic change occurs at a constant rate and can be used to measure time since species shared a common