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Transcript
Who Lives Where, and Why? • • • • Tolerance limits and evolution Evolution and Ecosystems Ecosystems/Community Properties Communities in Transition - Succession 1 Fig. 4.4 i.e. Temperature or Precipitation 22 Cold, oxygenrich water Can tolerate warm, low oxygen water 33 Adaptation • Two types of adaptation i.e., acclimation – dogs growing – By individuals Winter coat • Adjustment to conditions – By population • Through genetic mutations creating new traits • When a population adapts and a new species is created, this is evolution – Evolution operates by Natural Selection Survival of the fittest OR more successful at passing on their genes 4 Similar to Fig. 4.9 Specialized according 55 to food source Evolution • New species are created through Natural Selection, when adaptive traits make it possible for a segment of the population to survive in a different environment and/or use a new resource. – New trait created by random genetic mutations – Trait improves survival and so gets passed on to future generations – Over time, segment of the population with new trait becomes separated from the rest of the population and the two no longer interbreed. – Once interbreeding ends, the two are now separate species • Number of species limited by how far the resources can be partitioned 6 Partitioning of winter feeding grounds 77 Evolution • Number of species limited by how far the resources can be partitioned • Each species carves out its ecological niche 8 Competition for resources causes evolution Fig. 4.7 99 Fig. 4.8 10 10 Evolution to Ecosystems • Evolution creates new species • Species live in and compose biota in ecosystems – Species: Small scale, adapted to a microenviroment – small spatial scale – Ecosystems: Large scale, adapted to a macroenvironment – large spatial scale • Ecosystems include biota (communities of organisms) and their physical environment (i.e. atmosphere/crust or ocean) 11 BIOTA: Important concepts for Environmental Science • • • • Community productivity Community complexity Community resilience Community changes with time 12 Community Properties • Productivity – Primary: converting solar energy to chemical energy • Can be very productive, but not necessarily efficient • Abundance and diversity of species – often inversely related 13 Fig. 4.21 14 14 Energy from Sun! Extremely high Productivity Systems: Tropical rain forests Coral reefs 15 Community Properties • Productivity – Primary: converting solar energy to chemical energy • Can be very productive, but not necessarily efficient • Abundance and diversity – often inversely related • Complexity Will depend on community • Resilience and stability structure (keystone species?) and distribution of nutrients 16 Keystone Species • Species that is key to Community structure – Analogy: Pick-up sticks are Community of species, the stick that you pull out and they all fall down is a keystone species 17 Giant Kelp is keystone sp. on Pacific Coast of California • Provides food, shelter and structure for whole community, affecting resiliency of ecosystem to change • Ecosystem severely impacted when sea otters were hunted, as they ate fewer urchins, which could then eat more kelp Fig. 4.20 – sea otters 18 Communities in Transition • Primary and secondary succession 19 Secondary Primary 20 20 Fig. 4.26 After Ice Age, for example 21 21 Pioneer Community on Hawaiian Lava 22 23 23 Kettle Lakes in glaciated regions like Minnesota 24 24 Eastern trees 25 25 26 26 Succession and Climax Communities • Do communities always return to the same group of species? – NO – Example: – Addition of P to lake with submerged plants initially makes plants grow more – If P gets high enough, floating communities (algae and other plankton) shade bottom and submerged plants die – If P goes back down, submerged plants may not come back because floating communities will remain and sediments have built up on the bottom 27 Worries for Succession in MN forests • Global warming – Species with different tolerance limits step in – Diseases/pests more successful with warmer climate • Invasive species – Non-native species out compete native species and change community – Non-native Pests challenge native species 28 The End. Back 29