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Test 2 Notes

15 Pages

Biological Sciences
Course Code
BIOL 1202

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Chapter 26 Phylogeny and the Tree of LifePhylogeny the evolutionary history of a species or group of related speciesSystematics an analytical approach to understanding the diversity and relationships of organisms Concept 261 Phylogenies show evolutionary relationshipsTaxonomy the ordered division of organisms into categories based on a set of characteristics used to assess similarities and differences Binomial Nomenclature Carolus LinnaeusThe two part format of the scientific name of an organismThe binomial name consists ofoGenus and speciesoThese are always written in a different font ex italicsoGenus is always capitalized species is always lowercaseoex Homo sapiensHierarchical ClassificationLinnaeus also introduced the system for grouping species in decreasingly broad categoriesKingdom Phylum Class Order Family Genus Species Figure 263Classification of humanKingdom AnimaliaPhylum ChordataClass MammaliaOrder PrimatesFamily HominidaeGenus HomoSpecies H sapiens Linking ClassificationPhylogenySystematists depict evolutionary relationships in branching phylogenetic treesEach branch point node represents the divergence of two species Lines represent lineages Figure 264Which of the following represents the correct order of taxa from the most inclusive to the least inclusiveDomain kingdom phylum class order family genusConcept 262 Phylogenies are inferred from morphological and molecular dataMorphologicalMolecular Homologies Phylogenetic history can be inferred from similarities in homologous structures and genes when compared among organismsGenerally oSimilar morphology and similar DNA sequences closely related speciesBut beware of analogous structures or molecular sequences aka homoplasiesoSimilarity may be due to convergent evolution analogy not shared ancestry homology Concept 263 Shared characters are used to construct phylogenetic treesCladisticsCladogram a diagram depicting patterns of shared characteristics among speciesClade within a cladogram a group that includes an ancestral species and all of its descendantsA valid clade is monophyletic Figure 2611Monophyletic GroupingMade up of an ancestral species and all of its descendentsFigure 2610aParaphyletic GroupingConsists of an ancestor and some but not all of that ancestors descendants Figure 2610bPolyphyletic GroupingGrouping that lacks the common ancestor of the species in the groupFigure 2610cShared AncestralShared Derived CharacteristicsShared ancestral characteristic homologous structure that predates the branching of a particular clade from other members of that cladeShared derived characteristic evolutionary novelty unique to a particular clades figure 2611Shared Ancestral CharacterExample backbones in mammalsAll mammals have backbones but a backbone doesnt distinguish mammals from other vertebrates because all vertebrates have backbonesSo this character originated in an ancestor of mammals and vertebrates Shared Derived Character
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