Lecture 11 19 October fw eco

Lecture 11 19 October fw eco - Temporal and spatial factors...

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Temporal and spatial factors influencing biodiversity The ultimate source of biodiversity is evolution 2 terms associated with the evolution of biodiversity are: Endemism – Endemic organisms are those that occur only in one area. The fish family Centrarchidae (sunfishes) are endemic to N. America. The Rio Grande darter is endemic to tributary streams of the lower Rio Grande Texas wild rice is endemic to a 2-mile reach of the San Marcos River. Adaptive radiation – evolution of many species from one or a few founder species. Adaptive radiations tend to produce endemics. Commonly found in many ancient lakes around the world In the southwestern US an adaptive radiation of pupfishes has occurred in many isolated basins and drainages.
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Adaptive radiation Commonly occurs following mass extinctions, or when species move into new, unoccupied regions (e.g. post-glaciation).
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The ancient tectonic lakes contain a large proportion of freshwater biodiversity , with unique assemblages of vertebrates and invertebrates – especially when compared to the Great Lakes of North America . Lake Baikal has 377 endemic crustacean species (mostly amphipods), 86 endemic turbellarians, 98 endemic mollusks, and 29 endemic fish species. The African rift lakes (Tanganyika, Malawi, Victoria) are even more diverse with regard to fishes. Especially members of the family Cichlidae . A wide variety of adaptations have corresponded to these radiations.
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Behavioral diversity is also extremely high in these cichlids. The obvious question that comes to mind is… why does a particular group diversify? Chance to a certain extent.
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This note was uploaded on 11/09/2010 for the course NRM 2305 taught by Professor Staff during the Spring '08 term at Texas Tech.

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Lecture 11 19 October fw eco - Temporal and spatial factors...

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