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Week11 - Written Report Required one reference that is not...

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4/13/2010 1 Written Report Required: one reference that is not web based – must be a journal or textbook (not our textbooks) http://library.ttu.edu/ North America Divided into 76 ecoregions Based on: •fish, •amphibians, •Crayfish, •unionid mussels, •aquatic reptiles http://www.feow.org/ Biological diversity The ultimate source of biological diversity is evolution http://www.utexas.edu/utpress/largeimage/1885696361.jpg http://www.tamu.edu/upress/BOOKS/2007/thomas.htm Temporal and Spatial Factors Influencing Evolution of Freshwater Organisms Time- ancient lakes and watersheds have many unique species and high diversity Lake Baikal has 377 endemic crustacea , 86 turbellaria , 98 mollusks , 29 fish, and a freshwater seal Mississippi River Drainage: geologically stable, 227 native unionid mussels, 375 species of fish (glacial refuge) http://www.salemstate.edu/~lhanson/gls100/image1/mississippidrainage.gif
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4/13/2010 2 Baikal Tanganyika Malawi Victoria Ohrid Great Lakes 0 100 200 300 400 500 600 700 800 900 Taxa (number) Endemic teleosts Cosmopolitan teleosts Endemic molluscs Cosmopolitan molluscs Endemic crustaceans Cosmopolitan crustaceans fish Lake Baikal endemics •Crustaceans (377) •Amphipods * •50 genera •261 species •73 subspecies •Turbellarians (86) •Mollusks (98) •Fish (29 endemics) •26 sculpins •Diatoms (~50% ~679 sp. endemic) http://www.kbinirsnb.be/general/sections/amphi/carcimage.htm www.baikalscience.org Lake Tanganyika endemics 126 cichlids 12 of 20 leeches 45* of 60 gastropods 33 of 69 copepods 74 of 85 ostracods 22 of 25 decapods Adaptive radiation Evolution of many species from a single or a few founder species Darwin’s finches –Galapagos Islands Amphipods –Lake Baikal Cichlid fish –Lake Tanganyika
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4/13/2010 3 The endemic cichlid fishes of Lakes Malawi, Tanganyika and Victoria are classic examples of rapid speciation and adaptive radiation The adaptations behind these radiations result from the great variability of cichlid feeding structures: because of intense competition for food, species have evolved many specializations to exploit an incredible array of diets. Species have evolved to specialize on vascular plants, algae, insects, snails, fish, fish eggs or larvae, ectoparasites of other fish, plankton, and the scales or fins of other fish, . Other adaptations include novel feeding behaviors, peculiar structural adaptations, and use of mimicry. http://www.thisviewoflife.org/evolution/cichlid.html http://evolution.berkeley.edu/evosite/evo101/images/cichlids.gif AKA: Lake Nyasa 8 th largest lake, 560 km long x 75 km wide ~1000 fishes http://www.vagabonding.com/photos/malawi/DSC01998_lake_malawi _fish.jpg Biological diversity Ultimate source is evolution 1. Time available 2. Reproductive isolation http://sites.google.com/site/coririchards/bocasvariationcopy.jpg Geographic isolation unique groundwater fauna related to isolation dispersal ability linked to degree of isolation temporary pools can have many endemic species Temporal and Spatial Factors Influencing Evolution of Freshwater
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