Slide 1Slide 2Slide 3Tajima’s relative rate testTajima’s relative rate testRadiationsCauses of nonadaptive radiationAdaptive radiation criteriaRecent common Ancestry Not equal monophylyPhenotype-environment correlationTrait utilityRapid speciationExamples of adaptive radiationsDarwin’s Finches Common ancestryDarwin’s Finches Phenotype-environment correlationsDarwin’s Finches - Trait utilityDarwin’s Finches Rapid speciationWest Indian AnolesWest Indian AnolesAnolis – Common ancestryAnolis Phenotype-environment correlationAnolis – Trait utilityAnolis – Rapid speciationOther examples of adaptive radiations?Key InnovationNectar spurs key innovationAquilegia adaptive radiationSlide 28Why are spurs a key Innovation?Other examples of key innovations?Lecture 14Bjørn ØstmanOffice hours: Tuesday 12:15-1, LSB 4111(or by appointment)Adaptive radiationKey innovationshttps://www.youtube.com/watch?v=FHlo_N34vuohttp://www.theonion.com/video/in-the-know-are-tests-biased-against-students-who--17966ABOHow to test molecular clock:Relative rate test – Tajima’s TestIs branch leading to B longer than that leading to A?mjij: = 5mijj: = 2E(m1) = E(m2)χ2 = (m1-m2)2/(m1+m2)m1 = nAGA + nACA + nATA + nGAG + nGCG + nGTG + nCAC + nCGC + nCTC + nTAT + nTGT + nTCT m2 = nAGG + nACC + nATT + nGAA + nGCC + nGTT + nCAA + nCGG + nCTT + nTAA + nTGG + nTCC Tajima (1993) Simple Methods for Testing the Molecular Evolutionary Clock Hypothesis Genetics 135: 599-607Taxon ATaxon BTaxon Oχ2 = (5-2)2/(5+2) = 1.286Tajima’s relative rate testABO1.286 < 3.841 Therefore CLOCK NOT REJECTEDχ2 = (5-2)2/(5+2) = 1.286Tajima’s relative rate testRadiationsNonadaptive radiationAn increase in taxonomic diversity or morphological disparity. Radiations may affect one clade or many, and be rapid or gradual.Adaptive radiationRapid radiation driven by one lineage’s adaptation to multiple nicheshttp://en.wikipedia.org/wiki/Evolutionary_radiationhttp://en.wikipedia.org/wiki/Adaptive_radiationhttp://en.wikipedia.org/wiki/Resource_%28biology%29http://en.wikipedia.org/wiki/Ecological_nicheResourcesA substance or object in the environment required by an organism for normal growth, maintenance, and reproduction.NicheAn organism’s way of life, including the resources it uses, as well as its particular habitat. A peak in the fitness landscape.Causes of nonadaptive radiation•Sexual selection causing diversification•Non-genetic associations with ecology - without adaptation1. Common ancestry of component species: specifically a recent ancestry. (Note that this is not the same as a monophyly in which all descendants of a common ancestor are included.)2. Phenotype-environment correlation: a significant association between environments and the morphological and physiological traits used to exploit those environments.3. Trait utility: the performance or fitness advantages of trait values in their corresponding environments.4. Rapid speciation: presence of one or more bursts in the emergence of new species around the time that ecological and phenotypic divergence is underway.Adaptive radiation criteriaDolph Schluter, UBCThe Ecology of Adaptive Radiations (2000)Recent common AncestryNot equal monophylyMonophyletic Group (Red)Common ancestry (Red)Phenotype-environment correlation1. Association between phenotypes of different species and environment.2. According to Schluter, this fits “adaptive” criteria.(He defines adaptation as current utility, so both adaptation and exaptation.)3. Association can be tested statistically.4. Phenotype differences MUST be genetic.Trait utility•Traits that vary with environment must be useful in that environment•Should be tested experimentally or theoretically (ideally both)Rapid speciation•Rapid evolution of reproductive isolation•Can be measured statistically–Rapid rate of branching on a tree–More species in one sister clade–High speciation relative to extinctionExamples of adaptive radiations•Darwin’s finches•West Indian Anolis lizards•ColumbinesDarwin’s FinchesCommon ancestryhttps://www.youtube.com/watch?v=iA0NF41tLn8Darwin’s FinchesPhenotype-environment correlationsInsectsSeedsVegetationGround dwelling/large bills (seed eaters)Tree dwelling/smaller bills (insectivores)Darwin’s Finches - Trait utility•Functional analysis of force related to bill size•Field observations (smaller billed birds took longer time to break seeds)Darwin’s FinchesRapid speciationAll species are genetically very closely related(Islands colonized about 3 million years ago)Petren et al. (1999)West Indian AnolesWest Indian AnolesJonathan B. Losos, Harvardhttps://www.youtube.com/watch?v=mEEfcEYcOg8Anolis – Common ancestry•Island Anoles derived from mainland (N America) in the last 40 million years•Not a monophyletic group–Central American group descended from island species–Another island genus is nested within AnolisAnolisPhenotype-environment correlationPhenotype (Limb length)Environment (Tree size)R = 0.43p-value = 0.02Anolis – Trait utilityEvidence from laboratory experiments:•Long limbed species run faster on broader surfaces (mimicking a wide branch)•Long limbed species fall more on narrow surfacesPhylogeny and habitat use of Anolis lizards on Puerto Rico.Anolis – Rapid speciationHighly variable speciation rates within genus.A. occultus is the sister group to all other West Indian anoles and many mainland species:• 109 species in Greater Antilles• Hundreds of mainland species109 speciesOther examples of adaptive radiations?Discuss…b.socrative.com: UCSBBJORNKey InnovationA novel trait that influences the ability to exploit previously unused resources.Nectar spurs key innovation•7 of 8 groups with nectar spurs have higher rate of speciation compared to sister group•Average 3-fold increase in speciation rate•Present in Columbines (genus Aquilegia)Scott Hodges, UCSBAquilegia adaptive radiationCommon ancestry:Phenotype-environment correlation:Colombines of different phenotype (color, spur length, orientation) live in different habitats.Pollinated by:hummingbirds (red, short, pendant)hawkmoths (white, long, upright)about 70 species vs. 1 species in sister genus semiauilegiaRapid speciation:Trait utility:Experimentally change upright to pendant, no hawkmothsSignificant difference in species number:• Aquilegia have spurs and 70 species.• Semiaquilegia has no spur.SemiaquilegiaWhy are spurs a key