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Chapter 5. Macroevolution: Processes of Vertebrate and Mammalian Evolution. Classification. Classification is used to order organisms into categories to show evolutionary relationships. Example - human classification Kingdom: Animalia Subkingdom: Metazoan Phyla: Chordata
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Chapter 5 Macroevolution: Processes of Vertebrate and Mammalian Evolution
Classification • Classification is used to order organisms into categories to show evolutionary relationships. • Example - human classification • Kingdom: Animalia • Subkingdom: Metazoan • Phyla: Chordata • Subphyla: Vertebrata • Class: Mammalia
Classification: Definitions • Metazoa • Multicellular animals. • Chordata • The phylum of the animal kingdom that includes vertebrates. • Vertebrates • Animals with segmented bony spinal columns; includes fishes, amphibians, reptiles, birds, and mammals.
Principles of Classification • The field that specializes in establishing the rules of classification is called taxonomy.
Principles of Classification • Homologies • Similarities based on descent from a common ancestor. • Analogies • Similarities based on common function, with no assumed common evolutionary descent. • Homoplasy • The separate evolutionary development of similar characteristics in different groups of organisms.
Two Approaches to Classification • Evolutionary systematics • Cladistics
Ancestral and Derived Characters • Ancestral characters • Derived characters
Evolutionary Trees • Development of Passenger Vehicles • The first divergence is between cars and trucks (I). • A later divergence occurs between luxury cars and sports cars (II).
Evolutionary Trees • Development of Passenger Vehicles • SUVs diverge from trucks, but like sports cars, they have a decorative racing stripe. • This is a homoplasy and does not make SUVs sports cars. • Classifications based on a characteristic that can appear independently in different groups can lead to an incorrect conclusion.
Evolutionary Relationships of Birds and Dinosaurs • (a) Traditional view, showing no close relationship. (b) Revised view, showing common ancestry of birds and dinosaurs.
Cladogram • Shows relationships of birds, dinosaurs, and other terrestrial vertebrates. There’s no time scale, and both living and fossil forms are shown along the same dimension. Ancestor- descendant relationships aren’t indicated.
Definition of Species • Biological species concept • Depiction of species as groups of individuals capable of interbreeding, but reproductively isolated from other such groups.
Definition of Species • Recognition species concept • The key aspect is the ability of individuals to identify members of their own species for purposes of mating. • Ecological species concept • The concept that a species is a group of organisms exploiting a single niche. • Phylogenetic species concept • Splitting many populations into separate species based on an identifiable parental pattern of ancestry.
Allopatric Speciation • Living in different areas. • Important in the divergence of closely related species from each other which leads to reproductive isolation.
Speciation • Process by which a new species evolves from a prior species. • Speciation is the most basic process in macroevolution.
Recognition of Fossil Species • The minimum biological category we would like to define in fossil primate samples is the species. • Variations • Intraspecific vs. Interspecific
Recognition of Fossil Species • Splitters vs. Lumpers
Recognition of Fossil Genera • A genus is a group of species composed of members more closely related to each other than to species from any other genus.
Continental drift • The positions of the continents during the Mesozoic (c. 125 m.y.a.). • Pangea is breaking up into a northern landmass (Laurasia) and a southern landmass (Gondwanaland).
Continental Drift • (a) Positions of the continents during the Mesozoic. Pangea is breaking up into a northern landmass (Laurasia) and a southern landmass (Gondwanaland). (b) Positions of the continents at the beginning of the Cenozoic.
Ecological Niches • The positions of species within their physical and biological environments, together making up the ecosystem. • A species’ ecological niche is defined by such components as diet, terrain, vegetation, type of predators, relationships with other species, and activity patterns, and each niche is unique to a given species.
Mammalian Evolution • The Cenozoic era is known as the Age of Mammals. • After dinosaurs became extinct, mammals underwent adaptive radiation, resulting in rapid expansion and diversification. • The neocortex, which controls higher brain functions, comprised the majority of brain volume, resulting in greater ability to learn.
Reptilian and Mammalian teeth • Mammals are heterodont, they have different kinds of teeth; incisors, canines, premolars, and molars.
Endothermic • Able to maintain internal body temperature by producing energy through metabolic processes within cells; characteristic of mammals, birds, and perhaps some dinosaurs.
Major Mammalian Groups • Monotremes • Marsupials • Placental
