9/28/201711Bake Sale• Anthropology Club Bake Sale– Today from 10am – 2pm– Willey Hall (right outside this very classroom!)– Any questions about Anthro Club can be answered at the bake sale table– Proceeds fund the Undergraduate Anthropology Club Annual Conference29/28/20172Darwin’s 5 theories regarding evolution1. Species change [evolution as such]2. All organisms share a common ancestry3. Evolution is gradual4. Evolution leads to speciation5. Evolution occurs through Natural Selection3Convergent Evolution9/28/20173Speciation: bridging micro- and macro-evolution• Micro-evolutionary processes (four forces) → patterns of Macro-evolution (speciation, common ancestry above the species level) 5?A common comment on the street:“Forming new species is impossible because the first reproductively isolated organism will be incapable of mating with any other organism”• This reasonable but unfounded misconception is based in the idea that speciation is an EVENT rather than a PROCESS getting there is half the fun!• Indeed, perhaps the very best evidence supporting evolution is the process of speciationSpeciation: bridging micro- and macro-evolution9/28/20174Scale of Macroevolution• Age of life on Earth ~ 3,500,000,000 years• Washington Ave. Bridge ~ 1,500 feet• Each foot ~ 26 million years• Each inch ~ 200,000 years (the age of our species, H. sapiens)• Thickness of your hair ~ 0.004 inches or 777 years• Plenty of time for speciation given documented microevolution…7Species?8• Life can be clustered into distinct types• Species are real biological concepts• Species are difficult to define"Liger couple" by Hkandy - Own work. Licensed under CC BY-SA 3.0 via Commons -https://commons.wikimedia.org/wiki/File:Liger_couple.jpg#/media/File:Liger_couple.jpgLiger: cross from a male lion and female tigerMule: cross from a male donkey (jack ass) and female horse (mare);Hybrid vigor but still sterile.9/28/20175Speciation as gene flowsamespeciesdifferentspecieshow do youget from complete hybridizationto NO hybridization?complete hybridizationno hybridization9The Biological Species Concept• Species are a group of interbreeding organisms• Reproductive isolation OR• Connected through gene flowAdjacent IslandsDistant Islands109/28/20176The Ecological Species Concept• Reproductive isolation not necessary• Natural selection keeps species distinct from one another• Relies upon the concept that hybrids have less Fitness.11The Ecological Species Concept• Almost half of all species notreproductively isolated• Some species have little or no gene flowPacific Checkerspot Butterfly (individual’s range = 100m; populations separated by 100s km)129/28/20177Allopatric Speciation• Geographic isolation, physical barrier• Combination of reproductive isolation and natural selection• Etymology: allopatric and alone, from Greek allos, other13Allopatric Speciation• Character displacement– Large-beaked birds outcompete medium-beaked birds in dry habitats– Move to wetter areas—selection favors small beaks– Example: Santa Cruz Island finches.• Reinforcement: – evolution of characters to increase reproductive isolation.149/28/20178Examples: Guenons of AfricaReinforcement can lead to the Species Mate Recognition Concept15Stages of incomplete hybridizationFunctional (non-gametic)incompatibilityBehavioral incompatibilityGeographic incompatibilityTemporal incompatibilityBiased sexratioSex-biased hybridfertilityReduced overall hybrid fertilitySecond generation hybrid sterilityHybrid sterilityHybrid inviabilityReduced hybridity169/28/20179Examples: ring speciesPhylloscopus trochiloides trochiloides: Greenish WarblerSpecies boundary: no mating17Examples: dogs• Dogs are all the same species?189/28/201710Examples: dogs• Dogs are all the same species?19Speciation as the interaction between the Biological & Ecological Species Concepts in historical time20Etymology:Parapatric = parallelSympatic = same9/28/201711Hamadryas Baboon: ♀-defense polygynyOlive Baboon: ♀-bondedParapatric Speciation in progress21229/28/20171223Lahr & Foley 2006derived traitsderived traitsderived traitsALA#5 ChimeIn Question:Which mechanism is acting when a physical barrier results in speciation?A. Allopatric speciationB. Parapatric speciationC. Sympatric speciationD. Biological species conceptE. Natural selection24Text 20082 plus your answer to 14352154567to answer via SMS9/28/201713Before we introduce the hominins, how do we tell who descended from whom?25Homology (ancestry) or Convergence (analogy)?Homology or convergence?269/28/201714Levels of analysisAs a wing…As a forearm…27Creating Evolutionary or Phylogenetic Trees28So, how do we chose which traits to examine when making trees?9/28/201715Creating Evolutionary or Phylogenetic Trees29ConvergenceAncestralShared DerivedDerived• Warm-blooded: yes yes yes yes• Hair color: tan grey black orange• Premolar #: 3 2 2 2• Tail: yes yes no noSpidermonkey Baboon Gorilla30Carrot Top9/28/20171631How are they related?Warm-blooded?yesyesyesyes329/28/201717Is warm-bloodedness a useful trait for determining relationships among these primates?yesyesyesyes33tanblackgrey orangeIs hair color a useful trait for determining relationships among these primates?349/28/201718322 2Is premolar # a useful trait for determining relationships among these primates?35yesyesnonoIs the presence of a tail a useful trait for determining relationships among these primates?369/28/201719Warm-bloodedLoss of premolarLoss of tail• Warm-blooded: yes yes yes yes• Hair color: tan grey black orange• Premolar #: 3 2 2 2• Tail: yes yes no no37Full orbital convergenceCladistics• Primitive or Ancestral characters, even though homologous, do not help in sorting relationships• Unique characters do not help in sorting relationships• Only SHARED, DERIVED characters can sort relationships within a
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