Biol 3350 1st Edition Lecture 23Outline of Last Lecture I. Phenetics vs. CladisticsII. Issues in Phylogenetic ReconstructionIII. Why use DNA for molecular phylogenetics?IV. PhylogeographyV. How did the Seychelles Tiger Chameleon cross the ocean?Outline of Current Lecture I. Biological Species ConceptII. Advantages and Disadvantages to Biological Species Concepta. Advantagesb. Disadvantages III. Morphospecies ConceptIV. Advantages and Disadvantages to Morphospecies Concepta. Advantagesb. DisadvantagesV. Phylogenetic Species ConceptVI. Advantages and Disadvantages to Phylogenetic Species Concepta. Advantagesb. DisadvantagesVII. Gray Treefrog Speciationa. Descriptionb. Biological Species Conceptc. Phylogenetic Species ConceptVIII. Reduction in gene flowIX. Reproductive isolationX. Premating isolating mechanismsCurrent LectureI. Biological Species Concepta. Ernst Mayr b. Interbreeding – breeding with another population of similar or not so similar organisms, then according to Mayr, you are the same species.i. If you cannot breed, then you are not the same speciesII. Advantages and Disadvantages to Biological Species Concepta. AdvantagesThese 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.i. Intuitive – conceptually makes sense that two different breeds couldn’t breed with each otherii. Complete lack of gene flow – no gray areasiii. Two main processes where species become isolated from each other and speciation occurs over time = genetic drift and natural selectioniv. Adaptation to different habitats will cause differences in allelic distributions because the favored allele will become more common over timeb. Disadvantages i. - Allopatric – organisms can’t physically meetii. If they are not in the same place at the same time, they can’t interbreed with each otheriii. Fossil – can’t tell if they are the same or different species because we do not know if they interbrediv. Hybridizing – two different parents so which species does the hybrid belong to?v. Asexual – parthenogenic à females produced eggs that are clones of justthemselves, no DNA from the males vi. Are females then a species of their own?vii. Biological species concept does not take into account the evolutionary processIII. Morphospecies Concepta. Looking at morphological traits and trying to come up with some measurement based on the differences of the features to distinguish two different speciesb. Often used for fossil speciesIV. Advantages and Disadvantages to Morphospecies Concepta. Advantagesi. Widely applicable- extant or extinct speciesii. Sexual or asexual organismsb. Disadvantagesi. Species designations may be arbitary because some species have a lot of phenotypic differences but some do not have a lot of morphological differences (like bacteria and fungi) à where do we draw that distinction linesV. Phylogenetic Species Concepta. Cracraftb. Based on phylogenetic systematicsi. Emphasis on cladogenesisii. Estimate phylogeny of closely related populationsiii. Species then identified as the smallest monophyletic groupc. Phylogenetic species concept is more evolutionary in focus à looking at the process of speciation through evolutiond. Terminal nodes have all of the extant or living speciese. Extinct species do not reach the terminal branch tipsf. If populations have become isolated, they would have diverged geneticallyVI. Advantages and Disadvantages to Phylogenetic Species Concepta. Advantagesi. Applicable to sexual and asexual organismsii. Applicable to fossil taxaiii. Takes evolutionary processes into accountb. Disadvantagesi. Little guidance with respect to which characters are most important to defining a speciesVII. Gray Treefrog Speciationa. Descriptioni. Hyla versicolor and Hyla chrysoscelis are two identically looking species but are actually different speciesii. Different chromosome number, yet they look identicaliii. There were 3 parental species that led to the formation of H. versicoloriv. They can’t mate with each other and produce fertile offspring, but in some regions they live in the same areav. No behaviorally isolated due to their mating callsvi. They are isolated by their different mating calls à do not breed together because the females of one species do not like the males of the othervii. Females come to the males to bread when they callb. Biological Species Concepti. No, they are not different species because lineages are not reproductivelyisolated from one another in sympatryc. Phylogenetic Species Concepti. Yes, they are different species because each lineage has separate origin and is part of monophyletic cladeVIII. Reduction in gene flowa. When you cut off gene flow, processes of natural selection and genetic drift cause populations to become more differentIX. Reproductive isolationa. Allopatry is physical isolationb. Population occupy geographic locations à serves as a barrier to gene flowc. Isolation in sympatryi. Secondary contact – area of overlap between the species may produce a hybrid zone as the separate areas experience speciationX. Premating isolating mechanismsa. Spatial separation – one species may breed in a marsh while the other breeds in open water areab. Temporal separation – one breeds early in the summer, the other breeds late in the summer (never get to mate, eventhough geographically in the same place)c. Behavioral isolationd. Mechanical isolation – copulation organ is very specific for each species and physically cannot transfer