1 Who Lives Where, and Why? Tolerance limits and evolution Evolution and Ecosystems Ecosystems/Community Properties Communities in Transition - Succession

2 2 Fig. 4.4 i.e. Temperature or Precipitation

3 3 Cold, oxygen- rich water Can tolerate warm, low oxygen water

4 Adaptation Two types of adaptation –By individuals 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 i.e., acclimation – dogs growing Winter coat Survival of the fittest OR more successful at passing on their genes

5 5Similar to Fig. 4.9 Specialized according to food source

6 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

7 7 Partitioning of winter feeding grounds

8 Evolution Number of species limited by how far the resources can be partitioned Each species carves out its ecological niche

9 9 Fig. 4.7 Competition for resources causes evolution

10 Fig. 4.8

11 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)

12 BIOTA: Important concepts for Environmental Science Community productivity Community complexity Community resilience Community changes with time

13 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

14 Fig Energy from Sun!

15 Extremely high Productivity Systems: Tropical rain forests Coral reefs

16 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 Resilience and stability Will depend on community structure (keystone species?) and distribution of nutrients

17 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

18 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 – sea otters

19 Communities in Transition Primary and secondary succession

20 Secondary Primary

21 Fig After Ice Age, for example

22 Pioneer Community on Hawaiian Lava

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24 Kettle Lakes in glaciated regions like Minnesota

25 Eastern trees

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27 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

28 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

29 The End. Back