Chapter 26: Phylogeny and the Tree of Life Phylogeny: the evolutionary history of a species or group of related species Systematics: an analytical approach to understanding the diversity and relationships of organisms Concept 26.1: Phylogenies show evolutionary relationships Taxonomy: the ordered division of organisms into categories based on a set of characteristics used to assess similarities and differences Binomial Nomenclature: The two part format of the scientific name of an organism The binomial name consists of o Genus and species o These are always written in a different font (e.g., italics) o Genus is always capitalized; species is always lowercase o E.g., Homo sapiens Hierarchical Classification: Linnaeus also introduced the system for grouping species in increasingly broad categories Keep Pipes Clean OF GaS – Kingdom, Phylum, Class, Order, Family, Genus, Species Kindly Professors Cannot Often Fail Good Students i. Kingdom - Animalia ii. Phylum – Chordata iii. Class – Mammalia iv. Order – Primates v. Family – Hominidae vi. Genus – Homo vii. Species – Homo sapiens Linking Classification & Phylogeny: Systematists depict evolutionary relationships in branching phylogenetic trees Each branch point (node) represents the divergence of two species Deeper branch points represent greater amounts of divergence Lines represent lineagesInterpreting Phylogenetic Trees: INSERT PICTURE Interior nodes represent common ancestors Taxa at tips represent living species/groups Rotating around any node leaves a phylogeny unchanged Which taxon on the tree below is most closely related to taxon C? i. A ii. B iii. D iv. B and D are equally closely related to C v. All of the above are equally closely related to C Which taxon on the tree below is most closely related to taxon A? i. B ii. C iii. D iv. All of the above are closely related to A Which of the following represents the correct order of taxa, from the most inclusive to the least inclusive? i. Domain, Kingdom, Phylum, Class, Order, Family, Genus ii. Species, genus, family, order, class, phylum, kingdom iii. Class, domain, family, genus, kingdom, order, phylum iv. Domain, phylum, order, family, class, genusConcept 26.2: Phylogenies are inferred from morphological and molecular data Morphological & Molecular Homologies: Phylogenetic history can be inferred from similarities in homologous structures and genes when compared among organisms Generally, similar morphology and similar DNA sequences = closely related species But, beware of analogous structures or molecular sequences (a.k.a., homoplasies) o Similarity may be due to convergent evolution (analogy), not shared ancestry (homology) Concept 26.3: Shared characters are used to construct phylogenetic trees Cladistics: Cladogram – a diagram depicting patterns of shared characteristics among species Clade within a cladogram – a group of species that includes an ancestral species and all of its descendants Monophyletic Grouping: Made up of an ancestral species and all of its descendants Only monophyletic groups qualify as legitimate taxa in cladistics Paraphyletic Grouping: Consists of an ancestor and some, but not all, of that ancestor’s descendants Polyphyletic Grouping: Grouping that lacks the common ancestor the species in the groupShared Ancestral & Shared Derived Characteristics: Shared ancestral characteristic: homologous structure that predates the branching of a particular clade from other members of that clade Shared derived characteristic: evolutionary novelty unique to a particular clade Which shared derived character allows us to infer that ((stink bugs + beetles) + lobsters is a clade? i. 1 pair antennae ii. Large claws iii. Compound eyes iv. 6 legs Which of the following is not a shared ancestral trait of the ((stink bugs + beetles) + (lobsters)) clade? i. 6 legs ii. 1 pair of antennae iii. simple eyes iv. molt skeleton Is the similarity between the Australian mole and the North American mole due to homology? 1. Yes, they share a recent common ancestor 2. No, they are similar due to random factors 3. No, they are similar due to convergent evolution analogous Concept 26.4: An organism’s evolutionary history is documented in its genome Gene Duplications and Gene Families: Gene duplication: the production of multiple copies of a gene within the genome Important type of mutation in evolution because it increases the number of genes in the genome Orthologous & Paralogous Genes: Orthologous genes: genes found in a single copy in the genome o Diverge only once speciation takes place Paralogous genes: result from gene duplication o More than one copy in the genome o Can diverge within the clade that carries themParalogous Genes: The Globin gene family has resulted from several gene duplication events Choose the pair of paralogous genes from the following list. 1. A human alpha hemoglobin and chimpanzee alpha hemoglobin – orthologous, homologous 2. Two alleles of the human alpha hemoglobin gene – different variety of same gene 3. Mouse insulin gene and yeast mating type gene – not connected in any way 4. Two different olfactory receptor genes – paralogous Chapter 27: Prokaryotes One thing that E. coli and other bacteria have in common with eukaryotes is the presence of _____. 1. Chloroplasts 2. Mitochondria 3. Nucleus 4. Ribosomes Concept 27.1: Structural and functional adaptations contribute to prokaryotic success Prokaryotes are unicellular o Some colonial forms Range in size from 1-5 micrometers o Thiomargarita namibiensis (750 micrometers) No membrane-bound organelles Circular chromosomesProkaryotic cells have a variety of shapes The three most common are spheres (cocci), rods (bacilli), and spirals (spirilli) Cell-Surface Structures Cell Wall: o Maintains cell shape, provides physical protection, prevents cell from bursting in a hypotonic environment o Composed of peptidoglycan in bacteria o May also have an outer phospholipid membrane Cell Surface Structures: A capsule (a sticky layer of polysaccharide or protein) may cover the cell wall of many prokaryotes Fimbriae and pilli allow prokaryotes to stick to their substrate or other individuals in a
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