102SN1 - Biology 102 Study Notes Exam 1 Chapter 20:...

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Kevin Kelleher, MTC Biology 102 Study Notes Exam 1 1 Biology 102 Study Notes Exam 1 Chapter 20: Classification of Living Things Taxonomy : the branch of biology concerned with identifying and naming organisms - a natural system of classification reflects the evolutionary history of organisms - naming and identifying organisms began with the Greeks and Romans - in the middle ages, organisms were described using long Latin descriptions - much later, John Ray, a British naturalist argued that each organism should have a set name The Binomial System - the number of known organisms expanded greatly in mid-eighteenth century due to European travel - common names vary with different languages, & the same name may refer to different organisms in different regions - Carolus Linnaeus developed the binomial system to name species - the binomial system of nomenclature names organisms using a two-part Latin name o first part is the genus ; closely related species are assigned to the same genus o second part is the specific epithet ; it usually provides something descriptive about an organism o a scientific name consists of both genus and specific epithet (e.g., Panthera tigris and Panthera leo ) o both names are italicized or underlined ; the first letter of only the genus name is capitalized o the genus can be abbreviated when used with a specific epithet if the full name was given before ( H. sapiens ) - the classification of organisms is an ongoing process o there are estimated to be between 3 and 30 million species living on earth o we have currently named one million species of animals and a half million plant and microorganismic species o some groups, such as birds, are nearly all known; some insect groups are mostly unknown Identification of a Species - Linnaeus considered each species to have a unique structure that made it distinct o distinguishing species on structure can be a problem because variations occur among members of the same species o males and females may have a different form, as well as juveniles and adults - the biological definition of a species : a group of organisms that interbreed and share the same gene pool o distinguishing species on the basis of reproductive isolation can be a problem o some species do not reproduce sexually o some species hybridize where their ranges overlap
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Kevin Kelleher, MTC Biology 102 Study Notes Exam 1 2 - when a species has a wide geographic range,they may tend to interbreed where they overlap; these populations may be named as subspecies o the rat snakes Elaphe obsoleta obsoleta and Elaphe obsoleta bairdi are subspecies of Elaphe obsoleta o including the subspecies makes this a trinomial , or three-part, name - in this chapter, a classification approach is taken to the definition of species o the term “species” is used for a taxonomic category below the rank of genus o species share a more recent common ancestor with species in same genus than with those in other taxa o a taxon is a group of organisms in a classification category;
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102SN1 - Biology 102 Study Notes Exam 1 Chapter 20:...

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