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Chapter 18

PHY 120 Chapter Notes - Chapter 18: Comparative Anatomy, Speciation, Macroevolution

Course Code
PHY 120

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LamarckInheritance of Acquired Characteristicsnew traits arise in organisms because of their needs
Lysenko—crop failures and famine… learned about heredity and genes
Darwin—organic evolution…artificial selection is selecting those traits that seem desirable and then
breeding plants/animals with those traits… survival of the fittest…natural selection
Natural Selection: a mechanism that accounts for differential survival and reproduction among members
of a species… proposed by Darwin and Wallace… favorable variations are more likely to be passed on
Sexual Selection: type of natural selection in which males compete for mates or females select mates
based on certain traits
Mendelgarden peas
Alternative expressions of genes account for some variation in populations
Most traits are controlled by many genes
Modern Synthesis: neo Darwinian view of evolution, a combination of ideas of scientists regarding
evolution that includes the chromosome theory of inheritance, mutations as a source of variation, but
rejects the idea of inheritance of acquired characteristics
Evolution is not static
Mutations: change in chromosomes/genes…change in hereditary info…create variations
Speciation: the phenomenon of a new species arising from an ancestral species
Species: biological term for a population of similar individuals that in nature interbreed and produce
fertile offspring
Allopatric Speciation: when a new species evolves from a small population that became isolated from its
parent population
Phyletic Gradualism: gradual accumulation of minor changes eventually brings about the origin of a new
Punctuated Equilibrium: little or no change takes place in a species during most of its existence, and
evolution occurs rapidly, giving rise to a new species in many years
Divergent Evolution: occurs when an ancestral species gives rise to diverse descendant species… leads to
descendants that differ markedly from their ancestors
Convergent Evolution: development of similar characteristics in distantly related organisms
Parallel Evolution: similar characteristics arising in closely related organisms
Microevolution: any change within a species
Macroevolution: any change in the origin of a new species
Mosaic Evolutuion: the concept that not all parts of an organism evolves at the same rate, yielding
organisms with features retained from the ancestral condition, as well as more recently evolved features
Cladistics: type of biological analysis in which organisms are grouped together based on derived
characteristics/evolutionary novelties/differentiating characteristics
Cladogram: shows the relationship among members of a group of organisms… better w living organisms
than fossils
Mass Extinction: accelerated extinction rates sharply reduce earths biotic diversity
Background Extinction: continual extinction of species
Classification, embryology, comparative anatomy, geographic distribution, fossil record
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