ENVR 202 Lecture 17: March 15th
27 Mar 2018
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Document Summary
March 15th: biotic effects of the isthmus of panama. Isthmus = narrow portion of land, enclosed by water and connecting two bodies of water: panama movement, took time, collisions caused andes mountains to form. Implications of circulation change: more snow and precipitation happening. Rates of change: a series of land masses that gradually form the isthmus. Effects on biological systems: direct, barrier to dispersal is created which leads to speciation, new selection pressures that will lead to speciation, climactic changes occurs due to deflecting currents. Isolation of marine animals: land bridge as a corridor for dispersal of land creatures, land animals who could not swim between continents are now able to make the journey (enterchange of organisms) Indirect: climate changes, geological changes lead to subsequent changes in distribution. Before isthmus: south america was isolated (later it gets allot more animals, before the drake passage (land was frozen) so animals could move from south.
