2 Today’s Objectives: SOL BIO.8b-d TSW investigate and understand how populations change through time, including:How variation of traits, reproductive strategies, and environmental pressures impact on the survival of populationsRecognizing how adaptations lead to natural selectionHow new species emerge
3 Charles Darwin On the Origin of Species Sailed with the HMS Beagle Observations made in the Galapogos IslandsThese observations helped him form the theory of how species change over time called natural selection
4 What is Natural Selection? Natural selection is governed by the principles of genetics.
7 What is a Population?Populations evolve over many generations, individuals don’tPopulations are groups of interbreeding individuals that live in the same place at the same timeIndividuals in a population compete for resources with each other
8 How Does Evolution Work? Populations produce more offspring than the environment can supportThe unequal ability of individuals to survive and reproduc leads to the gradual change in a population over many generations
9 Mechanism for change in a population of organisms Animals who have greater fitness survive in environment and live to reproduceRandom changes (mutations) can lead to greater or less fitnessAdaptations allow an organism to survive better in their environment
10 Mutations & Variety Produced by Sexual Reproduction Allow for Diversity within a Population Genetic drift (caused by chance)BottleneckFounder effectGenetic equilibriumHardy-Weinberg lawIn H-W equilibrium, does not occur
11 Adaptations Can arise in response to environmental pressures TemperatureAntibiotic resistance in bacteriaPesticide resistanceMorphological changes in peppered moths
12 Types of Selection Directional Stabilizing Disruptive Extreme form favored by natural selectionStabilizingMiddle form most successfulDisruptiveTwo extreme forms successful in separate environments
13 How are new species created? Geographic isolationReproductive barriersChange in chromosome numbersAdaptive radiation
14 Types of Evolution Convergent evolution Divergent evolution Dolphins & fishesWings of bees & batsDivergent evolutionDarwin’s finchesAdaptive radiation
15 How fast does evolution occur? GradualismDarwinSpecies change slowly over timePunctuated EquilibriumGould & LewontinSpecies can make rapid “leaps” in evolutionModern SynthesisParts of both are correct
Your consent to our cookies if you continue to use this website.