BIOL 201 1st Edition Lecture 11Outline of Previous LectureI. Classificationa. Taxonb. LinnaeusII. Phylogeneticsa. Phylogenetic treeIII. Properties of phylogenetic treesa. Unrooted treeb. Rooted treec. Monophylyd. Paraphylye. PolyphylyIV. Building phylogenetic treesa. Characteri. Discreteii. continuousb. Homologousc. Character stated. Phylogenetically informative/synapomorphye. ParsimonyOutline of Current LectureI. Phylogenetic analysis – a difficultya. Homoplasyi. Causes of homoplasyII. Comparative methoda. Order of evolutioni. Hypothetical exampleb. correlationIII. Implications of phylogenetic thoughta. Hierarchyb. classificationIV. Speciationa. Diversityb. Species conceptsCurrent LectureI. Phylogenetic analysis – a difficultya. Homoplasy: similarity that is NOT inherited from a common ancestor; opposite of homologyi. Causes of homoplasy1. Convergent evolution: independent evolution of similar morphological character states from different parts of the tree; often use different developmental pathwaysa. Ex: vertebrate eyes and cephalopod eyes are verysimilar even though they evolved completely separatelyb. Ex: sabertooth seen in different species that evolved separately2. Parallel evolution: similarity occurring independently indifferent parts of the tree; usually close parts of the tree with the same developmental pathway; also called parallelisma. Homoplasy because tend to group together even though there are species between them that don’t share the character stateb. Ex: similar wing patterns in Lepidoptera butterflies which are closely related taxa3. Evolutionary reversals: when you have a taxa that has a certain character; you’re evolving away from that character and one of the species in the basal group evolves backa. Ex: teeth in Gastrothecaguentheri frogs; frogs don’t have teeth in their lower jaw but this one does like their ancestors didII. Comparative method: the use of comparisons of sets of species to test hypotheses about evolution; helps to know the evolutionary relationship between species in questiona. Order of evolutioni. Hypothetical example- lizards; 2 traits: habitat generalists and large body sizeii. Question 1: Is large body size an adaptation to being a habitat generalist? Based on the phylogenetic tree in the powerpoint which shows that being large evolved before being a generalist;the answer is no. iii. Question 2: Is being a habitat specialist and adaptation to smallbody size? Can’t tell from the phylogenetic tree in powerpoint because being small and a specialist is ancestraliv. Question 3: Is being a habitat generalist an adaptation to large body size? Based on the phylogenetic tree in the powerpoint the phylogeny is consisten with this hypothesis because large body size evolved before being a generalist.1. Saying yes to question is too strong because only 6 lizards were studied- sample size is too small2. Also phylogeny could be wrong or may not go back far enoughb. Correlation: question of whether or not two characters are correlated when you’re looking across different speciesi. Can’t determine without looking at phylogenyii. # of data points may cause problems with correlations; need more to see correlationIII. Implications of phylogenetic thoughta. Hierarchy- originated with Aristotle’s scalaenaturaei. Related to phylogeny not hierarchyii. Primitive doesn’t mean worse; it just means more ancestralb. Classification- certain things you don’t want to do when classifying like naming groups that aren’t monophyletici. Ex: pongidae taxa includes chimps, gorillas, and orangutans butshould also include humansii. Ex: reptile group should include birds but it doesn’tiii. *anything other than species has no biological meaning; just a way to categorize organismsIV. Speciation: process by which nature breaks things into species; hard to determine what is a speciesa. Diversity: usually only consider animals or mammals but also includesthings like viruses and fungii. Insects take up most of diversity pie chartsii. Species are still being discovered to this day.iii. Estimates of # of species range from 3-5 million to 30 millionb. Species concepts- no set definition for what a species is so have concepts i. Biological species concept: species are groups of actually or potentially interbreeding natural populations that are reproductively isolated; commonly used and accepted1. Problems- can hybridize freely and this would be a different species so not reproductively isolatedii. Evolutionary species concept and phylogenetic species conceptalso exist1. Evolutionary- species is a single lineage of populations or organisms that maintain its identity from other such lineages2. What about asexuals though? Do we define every lineage as a new species or not? Can’t really apply evolutionary but it fits our concept of what a species