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Lecture 11

BIOL215 Lecture 11 Notes.pdf

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Biology (Sci)
BIOL 215
Neil Price

BIOl215 Lecture 11 Notes What types of mutations are most likely to fuel evolution as discussed in class: •By messing with the genotype, you mess with the phenotype •Not everything that changes in your genotype will show up on the phenotype Speciation: the process by which new species arise. •The evolution of reproductive isolation within an ancestral species, resulting in two or more descendant species Species: A complex concept with carious definitions, a fundamental taxonomic category to which individual specimens are assigned Biological species concept By far the most popular species concept applied to sexually reproducing organisms • •Defined as a reproductively isolated community in which all individuals potentially or actually interbreed amongst themselves, but are genetically isolated from other groups Advantages: • • Defines species on the basis of criteria important to their evolution - that is reproductive isolation • Members of the species self-define the boundaries of their own species •Disadvantages: • Exceptions exist, different species sometimes do interbreed • Takes too much time to test - not always feasible Evolutionary species concept •Defined as "an ancestral-descendant sequence of of populations evolving separately from others and with its own evolutionary role and tendencies." •Includes Paleospecies, which are the chronological series of similar forms •Advantages: • Applicable to living and extinct groups and sexual and asexual organisms •Disadvantages: Not operational - what does "evolutionary role and tendency" mean? • • Uses morphological criteria in the end • A sequence of fossil forms not always available due to poor preservation Phenetic species concept •Species under the PSC are composed of individuals that are phenotypically similar (includes morphology, physiology, behaviour) •Group species based on how they look •Therefore, they are distinguished from other species by phenotypic differences •This includes morphospecies - morphological species contemporary and extinct species which form "natural" breaks in anatomical appearance •Advantages: • Can be applied more easily •Disadvantages: • Requires some arbitrary decisions What of distantly related species are similar in appearance (i.e. shark fin vs. dolphin fin) • Phylogenetic species concept •Defined as a monophyletic group composed of "the smallest diagnosable cluster of individual organisms within which there is parental pattern of ancestry and descent" •Includes agamospecies - based on genetic similarity •Monophyletic groups (clusters) are defined by unique characters (in most cases variation
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