2011 Slide Set XII short Spr11

2011 Slide Set XII short Spr11 - Homo sapiens Quercus...

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Unformatted text preview: Homo sapiens Quercus virginiana Drosophila melanogaster I. Binomial nomenclature- 2-part scientific name- from Linnaeus- genus species (Virginia oak) (fruit fly) Why have a scientific name for each organism? Leaves and flowers Seeds Different common names can exist for the same species ( Bidens alba ): Beggar’s ticks Sticktight Burr marigold Devil’s bootjack Pitchfork weed Rayless marigold Or: the same common name can be used for multiple species. e.g., at least 80 different species in North America are called “goldenrod” (so scientific names eliminate confusion) Solidago canadensis Solidago juncea Solidago sempervirens What is a species? How to recognize or define a distinct species?(not a trivial problem!) Difficult to arrive at a standard/uniform definition of what a "species" is that applies to all organisms. B. The morphological species concept- a species is defined/recognized based on shared structural similarities (Can you envision any problems with this?) Male Female e.g., Morphological variation exists among individuals within a species…so where do you draw the line? Might be mistaken as separate species? Another complication: morphology can change drastically during the life cycle of a species ! larval tadpole Aquatic Gills Herbivorous Swimming adult frog Terrestrial Lungs Carnivorous Jumping metamorphosis Might be mistaken as separate species? Cryptic species: 2 species that are morphologically indistinguishable, but genetically very different. California fairy shrimp Tallahassee fairy shrimp Both are called Streptocephalus sealii, but… …cytochrome oxidase I gene = 24% difference in DNA sequence A species is a population or group of populations whose members have the potential to interbreed and produce viable and fertile offspring. eastern and western meadowlarks Fig. 24.3 C. Biological Species Concept (Ernst Mayr, 1942) The biological species concept is based on the potential to interbreed rather than physical similarity. “Preferred” definition because it recognizes the genetic distinctiveness of a species. Limitations to the Biological Species Concept 1. Not feasible to assess reproductive compatibility for every living thing! 2. Some (extinct) species are known only from fossils (= “paleontologists species”) so can’t assess reproductive compatibility!) Limitations…(cont.) 3. some species are asexual (so can’t assess reproductive compatibility!) Prokaryotes (reproduce by binary fission) triploid parthenogenetic lizard (only females: unfertilized eggs develop) some triploid dandelions produce seeds without meiosis The magrove killifish is a self-fertilizing hermaphrodite! Leopard frogs - populations vary in...
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This document was uploaded on 11/03/2011 for the course BIO bsc2011 at FSU.

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2011 Slide Set XII short Spr11 - Homo sapiens Quercus...

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