I. WHAT IS A SPECIES?A. EMPHASIZE PROCESS1. BIOLOGICAL SPECIES CONCEPT2. RECOGNITION SPECIES CONCEPTB. EMPHASIZES PATTERNS1. PHYLOGENETIC SPECIES CONCEPTSPECIATION:1. HOW DOES ONE GENE POOL SPLIT INTO TWO?2. WHAT MAINTAINS SEPARATE GENE POOLS?II. REPRODUCTIVE ISOLATING MECHANSIMSA. EXTRINSIC BARRIERS1. GEOGRAPHIC2. ECOLOGICALII. REPRODUCTIVE ISOLATING MECHANSIMSA. EXTRINSIC BARRIERSB. INTRINSIC BARRIERS1. PREZYGOTIC-PREMATING-LOCK AND KEY-GAMETIC INCOMPATIBILITY2. POSTZYGOTIC-ZYGOTE INVIABILITY-HYBRID DISADVANTAGE-HYBRID DEATH OR STERILITYIs reproductive isolation a direct or by-product of evolution?IV. GEOGRAPHY OF SPECIATIONA. ALLOPATRYB. SYMPATRYC. PARAPATRYABABA BV. MODELS OF SPECIATION1. ALLOPATRY A. DIVERGENT NATURAL SELECTION-GEOGRAPHICALLY ISOLATED POPULATIONS DIVERGE IN RESPONSE TO NOVEL ENVIRONMENT OR NEW SELECTIVE PRESSURES-ADAPTATION TO NEW ENVIRONMENT RESULTS IN REPRODUCTIVE ISOLATION V. MODELS OF SPECIATION1. ALLOPATRY A. DIVERGENT NATURAL SELECTION• POPULATIONS (OR SPECIES) DIVERGE IN RESPONSE TO FOOD RESOURCES• CHANGE IN BILL AND HEAD MORPHOLOGY PREDICTION: CHANGES IN MORPHOLOGY RESULTS IN REPRODUCTIVE ISOLATIONV. MODELS OF SPECIATION1. ALLOPATRY A. DIVERGENT NATURAL SELECTION• ARE DIFFERENCES IN HEAD MORPHOLOGY USED FOR CONSPECIFIC RECOGNITION?SUBJECT MODEL NO. APPROACH NO. PECKSG. scandens2.8 ± 0.42.0 ± 0.4 1.6 ± 0.97.9 ± 4.7differentRatcliffe and Grant 1983V. MODELS OF SPECIATION1. ALLOPATRY A. DIVERGENT NATURAL SELECTION• ARE DIFFERENCES IN HEAD MORPHOLOGY USED FOR CONSPECIFIC RECOGNITION?SUBJECT HEAD MODEL NO. APPROACH NO. PECKSG. scandens3.6 ± 0.82.0 ± 0.4 2.5 ± 0.85.4 ± 1.9G. scandens BODYG. scandens BODYdifferentV. MODELS OF SPECIATION1. ALLOPATRY A. DIVERGENT NATURAL SELECTION• ARE DIFFERENCES IN HEAD MORPHOLOGY USED FOR CONSPECIFIC RECOGNITION?SUBJECT HEAD MODEL NO. APPROACH NO. PECKSG. scandens2.5 ± 0.62.9 ± 1.1 2.1 ± 1.90.6 ± 0.4G. fortis BODYG. scandens BODYnot differentV. MODELS OF SPECIATION1. ALLOPATRY A. DIVERGENT NATURAL SELECTION• ARE DIFFERENCES IN HEAD MORPHOLOGY USED FOR CONSPECIFIC RECOGNITION?SUBJECT HEAD MODEL NO. APPROACH NO. PECKSG. scandens2.6 ± 0.61.6 ± 0.2 3.1 ± 1.62.7 ± 1.3G. fortis BODYG. scandens BODYnot differentSTUDY SUGGESTS THAT BOTH HEAD AND BODY SIZE ARE IMPORTANTV. MODELS OF SPECIATION1. ALLOPATRY A. DIVERGENT NATURAL SELECTIONDO CHANGES IN HEAD MORPHOLOGY INFLUENCE OTHER TRAITS?Podos et al. 2004V. MODELS OF SPECIATION1. ALLOPATRY A. DIVERGENT NATURAL SELECTIONCHANGES IN HEAD MORPHOLOGY INFLUENCE SONG PRODUCTIONPodos 2001intraspecific variation: G. fortisinterspecific variationV. MODELS OF SPECIATION1. ALLOPATRY A. DIVERGENT NATURAL SELECTIONSONG IMPORTANT IN CONSPECIFIC RECOGNITIONSONG TYPEG. fortisG. scandensNUMBER OF NEIGHBORS ATTRACTED230425Ratcliffe and Grant 1983V. MODELS OF SPECIATION1. ALLOPATRY A. DIVERGENT NATURAL SELECTIONOTHER STUDIES SHOWING NS AND SPECIATIONThree-spined stickleback feedingPea Aphids host plant Walking sticks host plantHeliconius butterflies warning colorationV. MODELS OF SPECIATION1. ALLOPATRY B. DIVERGENT SEXUAL SELECTION-DIFFERENCES IN MATE CHOICE PROCESS RESULTS IN DIFFERENCES IN SIGNALS USED IN COMMUNICATION-CHANGES IN SIGNALS RESULTS IN REPRODUCTIVE ISOLATION (PREMATING)PREDICTIONS: DIVERGENCE ONLY IN SECONDARY SEXUAL CHARACTERSPREDICTIONS: DIVERGENT CHARACTERS USED IN CONSPECIFIC RECOGNITIONGryllus spp. crickets by Gray and Cade (2000)PREDICTION 1: “SPECIES” SHOULD ONLY DIFFER IN SECONDARY SEXUAL CHARACTERS-CRYPTIC SPECIES: INDISTINGUISHABLE MORPHOLOGICALLY-ONLY DIFFER IN MALE SEX TRAIT: CALL RATEGryllus rubensGryllus texensisV. MODELS OF SPECIATION1. ALLOPATRY B. DIVERGENT SEXUAL SELECTIONPREDICTION 1: “SPECIES” SHOULD ONLY DIFFER IN SECONDARY SEXUAL CHARACTERS-CRYPTIC SPECIES: INDISTINGUISHABLE MORPHOLOGICALLY-ONLY DIFFER IN MALE SEX TRAIT: CALL RATEGryllus spp. crickets by Gray and Cade (2000)V. MODELS OF SPECIATION1. ALLOPATRY B. DIVERGENT SEXUAL SELECTIONPREDICTION 2: FEMALES SHOULD USE DIVERGENT TRAITS IN RECOGNIZING CONSPECIFICSGryllus spp. crickets by Gray and Cade (2000)V. MODELS OF SPECIATION1. ALLOPATRY B. DIVERGENT SEXUAL SELECTIONOTHER STUDIESTAXA TRAITHAWAIIAN CRICKETS SONGBOWERBIRDS BOWER STRUCTURE JUMPING SPIDERS MALE COLORATIONHAWAIIAN Drosophila HEAD SIZE (COURTSHIP)V. MODELS OF SPECIATION1. ALLOPATRY B. DIVERGENT SEXUAL SELECTIONV. MODELS OF SPECIATION1. ALLOPATRY 2. SYMPATRYA. DIVERGENT NATURAL SELECTIONPREDICTIONS: POPULATIONS DIVERGE IN SYMPATRYPREDICTIONS: POPULATIONS DIVERGE IN RESPONSE TO SPECIFIC ECOLOGICAL FACTORS PREDICTION: HABITAT SPECIFIC MATING RESULTS IN REPRODUCTIVE ISOLATIONV. MODELS OF SPECIATION1. ALLOPATRY 2. SYMPATRYA. DIVERGENT NATURAL SELECTION-POPULATIONS DIVERGE IN RESPONSE TO SPECIFIC ENVIRONMENTAL FACTORS DESPITE NOT BEING GEOGRAPHICALLY ISOLATED -PRIME CANDIDATES: INSECT – HOST PLANT-NEED POLYMORPHISM AND DISRUPTIVE SELECTION-VERY STRICT MODEL BECAUSE GENE FLOW CAN PREVENT SPECIALIZATIONV. MODELS OF SPECIATION1. ALLOPATRY 2. SYMPATRYA. DIVERGENT NATURAL SELECTIONExample(?): apple maggot fly Rhagoletis pomonella-work by many started by Walsh (late 1800’s) and Bush.V. MODELS OF SPECIATION1. ALLOPATRY 2. SYMPATRYA. DIVERGENT NATURAL SELECTIONApple maggot fly Rhagoletis pomonella-MID 1800s, SOME SHIFTED TO DOMESTIC APPLES-NEW HOST RACESIS THIS AN EXAMPLE OF SYMPATRIC SPECIATION?V. MODELS OF SPECIATION1. ALLOPATRY 2. SYMPATRYA. DIVERGENT NATURAL SELECTIONExample(?):Apple maggot fly Rhagoletis pomonellaPREDICTION1: POPULATIONS DIVERGE IN SYMPATRYYES, RECORDS SHOW SHIFT TO NEW HOST PLANTS AROUND MID 1800V. MODELS OF SPECIATION1. ALLOPATRY 2. SYMPATRYA. DIVERGENT NATURAL SELECTIONExample(?):Apple maggot fly Rhagoletis pomonellaPREDICTION 2: POPULATIONS DIVERGE IN RESPONSE TO SPECIFIC ECOLOGICAL FACTORS -SHIFT FROM HAWTHORNE TO APPLEADVANTAGE?RECIPROCAL TRANSPLANTS OF EGGS (Prokopy and colleagues 1988): LARVAL SURVIVORSHIPAPPLE LARVAE = HAWTHORN LARVAE IN HAWTHORNAPPLE LARVAE = HAWTHORN LARVAE IN APPLE (BOTH DID POORLY!)V. MODELS OF SPECIATION1. ALLOPATRY 2. SYMPATRYA. DIVERGENT NATURAL SELECTIONExample(?): Apple maggot fly Rhagoletis pomonellaPREDICTION 2: POPULATIONS DIVERGE IN RESPONSE TO SPECIFIC ECOLOGICAL FACTORS -SHIFT FROM HAWTHORN TO APPLEADVANTAGE?-ENEMY FREE SPACE-TIMING OF EMERGENCE FROM THE GROUNDAPPLE PEAKS 3 WEEKS EARLIER THAN HAWTHORNAPPLE Rhagoletis LARVAE LEAVE APPLES 16 DAYS BEFORE HAWTHORNHAVE TO STAY IN DIAPAUSE LONGER OR WILL ECLOSE IN WINTER – SO APPLE FLIES DEVELOP SLOWER