ANT 102 1st Edition Lecture 7Outline of Last Lecture I. Speciation and CladisticsII. Biological Species Concept (BSC)III. Problems with BSCIV. Modes of SpeciationOutline of Current Lecture I. Ring SpeciesII. Extinction vs. Mass ExtinctionIII. Gradual EvolutionIV. Living FossilsV. Linnaean TaxonomyCurrent LectureEvidence that speciation is a processExamples of species complex:Prickly pear cactusRing species: two different populations in the same environment overlap but do not actively reproduce with each other greenish warbler: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.Ensatina salamander: Herring gull and lesser black-backed gull:Extinction:Cause: environment changes too rapidly and the appropriate genetic variation to adapt do not exist, a species can become extinctExtinction events occurred frequently in the past, and are readily observed in thefossil recordMass extinction: many species becoming extinct at about the same timeMore than 60% of living organisms disappear Usually brought on by a massive catastrophic event (asteroid impact)“The Big Five”: five major mass extinctions End of the Ice Age (12,000 ya)Last extinction on earth A drop in the number of species means that there are a higher proportionof niches in an environment that are empty—waiting for a new species to take up the spaceAdaptive radiation: rapid formation of many new species from a common ancestor following availability of new environment Evolution is GRADUALKey concept:Thesis: intellectual propositionAntithesis: reaction/counter to the initial propositionSynthesis: reconciliation between the thesis and antithesisPunctuated equilibrium: model of evolution where there are long periods of littleevolution and are followed by short periods of accelerated evolutionary change. For a while, this idea was presented in opposition to the Darwinian model of gradualism. Today, most scholars see both gradual and punctuated as validPunctuated or gradual depends on the nature of the external force**Adaptive radiations are punctuatedPunctuated Gradualism: populations are never in stasis, always going through long periods of slow change (gradualism) which may or may not give way to periods of rapid change (punctuation). Living fossils: living species or small group of related living species that retain primitive characteristics from fossil relatives with little modificationHave not experienced an adaptive radiationEx: tuatara lizardHorseshoe crabMazon Creek: Central IllinoisTully Monster (also state fossil!)Linneaus: created the way that we categorize organismsTaxonomy should reflect phylogeny (evolutionary history and relationships)Linnaean Taxonomy:Domain: eukaryaKingdom: Animalia (digest calories)Phylum: chordata (spine, central nervous system)Class: Mammalia (produce milk for offspring)Order: primates (grasping hands, large brains)Family: hominidae (no tail)Genus: homo (bipedal, complex cultural behaviors)Species: homo sapiensTypes of similarity: Homology: similarity due to common ancestryHomoplasy: similarity due to common function and NOT to common ancestry. These traits are analogous and due to convergent evolutionEx: cactus (originally from N and S America) and euphorbia Not related, but similarEx: giant armadillo, giant anteater and giant pangolinNot related, but similarHypothetical taxon: Winger (80’s Rock Band)Form taxon using criterion of similarity For Winger, they must have wings:Bats, bees, birds, Hawk Man, dragonsWings: homology or homoplasy?Levels of analysis: is it used as a wing or forearm?Comparison: How are they