Exam 2 - Generalized model of speciation 3 types of...

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Generalized model of speciation 3 types of speciation: 1. Allopatric: populations diverge as a result of geographic isolation 2. Parpatric: populations diverge in different environments within the same geographic range 3. Sympatric: different adaptations to similar environments Adaptive radiation is a process that takes place when a life form rapidly takes advantage of the many newly available ecological niches. Other examples of adaptive radiation: Lemurs on Madagascar: originally all of the world’s 60 species Drosophila flies in Hawaii: over 800 of the world’s 1250 species Darwin’s finches in the Galapagos: 13 endemic species found nowhere else 2 types of evolution: 1. Divergent: two or more new species form from a common ancestor, becoming more different through time 2. Convergent: descendents of different ancestors become superficially similar because they are adapting to the same environment The placental and marsupial mammals are not closely related but they have strikingly similar traits. Modes of Evolution: Punctuated Equilibrium and Phyletic Gradualism. The theory of punctuated equilibrium asserts long periods of evolutionary stasis are interrupted, or punctuated, by times of rapid evolution and speciation. Classification is used to order organisms into categories to show evolutionary relationships. It is divided by: Kingdom (Animalia) Phylum (Chordata) Class (Mammalia) Order (Primates) Family (Hominidae) Genus (Homo) Species (sapiens) 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 Tetrapods: having four feet, legs or leg-like appendages
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Taxonomy is the field that specializes in establishing the rules of classification. Organisms are classified first on the basis of physical similarities. Basic physical similarities must reflect evolutionary descent in order for them to be useful. Homology is similarities between organisms based on descent from a common ancestor (produced by divergent evolution). Analogy is similarities between organisms based on common function, not common descent (produced by convergent evolution). Ancestral traits are traits inherited by a group of organisms from a remote ancestor and thus not diagnostic of groups diverging after that time. Birds, reptiles, and mammals are all tetrapods. Derived (modified) traits are traits that are modified from their ancestral condition and are thus diagnostic of particular lineages. For example, reduction of body hair and upright locomotion. Shared-Derived traits are traits shared by related forms (i.e. species) that are considered the most
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Exam 2 - Generalized model of speciation 3 types of...

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