BIOL 152 1st Edition Lecture 8 Outline of Last Lecture - Mendelian Genetics Outline of Current Lecture Speciation Current Lecture- PhylogenyAnagenesis – overtime one species changes to a different type of speciesCladogenesis – presence of one species that diverge into two different species Biological species concept - populations or group of populations whose members have the potential to interbreed and produce viable offspring Reproductive Isolation - are biological factors that impede members of two species from producing viable, fertile offspringPrezygotic - prevent mating or fertilization- Habitat isolation- Temporal isolation- Behavioral isolation- Mechanical isolation- Gametic isolationPostzygotic - prevent viable, fertile hybrids- Reduced hybrid viability – can reproduce some hybrids These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Reduced hybrid fertility – can’t reproduce hybrids - Hybrid breakdown – can’t reproduce after many generationsLimitations of the Biological Species Concept- Cannot be usefully applied to all species- Fossils- Asexual organisms- Not enough is known about organismAdditional definitions for speciesMorphological species concept - are characterized by body shape, size, and structureEcological species concept - are characterized by species’ niche interactions with living and nonliving environment Phylogenetic species concept - are characterized by their phylogeny on the animal lineage and geneticsSpeciationAllopatric speciation - gene flow is reduced by physical barrier- Population separated in space - Allopatric speciation is much more common in animals- Gene flow prevents allopatric speciation - Secondary contact takes place and only then will it lead to hybridizationSympatric speciation - gene flow is reduced by reproductive barrier- Populations in same place, but separated through small barriers - More common in plants- Polyploidy can lead to speciation- Autopolyploidly – having an extra set of chromosomes when reproduced from the same species - Allolpolyploidy – when hybrids develop gametes that reproduce to make new species Hybridization - concept of species being separated by geographic barriers and their way of coming back together to reproduce viable offspringReinforcement - occurs when the hybrid offspring are selected against and the barrier between the species strengthens Fusion - occurs when the two species come together and reproduce many viable hybrid offspring, but leads to loss of divergent individuals. Geographic or other biological barriers are weakened Stability - occurs when both species survive and can also reproduce to make viable hybrid offspringSympatric - females living in the same geographic region chose males that look like them Allopatric - females living in different geographic regions, chose males of different species, but look similar to the species of the female Tempo of speciationGradualism - uniformitarianismPunctuated equilibrium - rapid speciation instantaneously in generationAdaptive radiation- Is the rapid evolution of many diverse species from a common ancestor upon introduction to new environmental opportunities- Cambrian Explosion lead to adaptive radiation Scale of EvolutionMicroevolution - how gene frequencies change in a population Macroevolution - the cumulative effects of speciation over vast amounts of time, is evolutionarychange above the species levelMacro-evolutionary Changes In most cases, complex structures evolved in increments from much simpler versions that performed the same basic function, this is known as exaptation, such as:- Feathers- Complex eyes- Avian wingsHomeotic genes - determines where plant and animal ‘appendages’ develop - Homeotic genes are the masters in regulating gene development- Encode specific Transcription Factors that control the expression of genes responsible foranatomical structureso Hox genesHeterochrony - an evolutionary change in the rate or timing of development- Allometry - science of studying the differential growth rates of the parts of a living organism- Paedomorphosis – timing of reproductive development relative to somatic organs such that the sexually mature stage retains juvenile body featureso