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Populations C-5-1

Populations C-5-1. Exponential Growth. Populations can grow exponentially if not kept in check. ~ for instance: one bacteria will become 2, then 4 then 8,then 64, then 512,then at the end of one day, there will be 4.72 x1021. Exponential Growth.

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Populations C-5-1

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  1. PopulationsC-5-1

  2. Exponential Growth • Populations can grow exponentially if not kept in check. • ~ for instance: one bacteria will become 2, then 4 then 8,then 64, then 512,then at the end of one day, there will be 4.72 x1021

  3. Exponential Growth • only happens when populations have every offspring survive to reproduce. • As resources become less available, offspring don't live as well. This stops population growth. • Carrying capacity • max # org. an ecosystem can support

  4. Exponential Growth • Human population has grown exponentially since the 1700's. • due to medicine and farming technology: • people live longer lives • vaccines lower death rates • more food supports more people • We have not reached carrying capacity yet, but some evidence shows we may reach 9 bill. by 2060

  5. Ecosystems are influenced by a combination of biotic (living organisms) and abiotic (physical) factors.

  6. Limiting Factors for populations • Density-dependent • Competition for food - more org. = less resources • Predation - predator-prey relationships keep each other in balance • Parasitism and Disease - keeps populations down by killing host

  7. Limiting Factors for populations • Density-indepenant • Drought / Climate extremes – extreme heat or cold, lack of or too much water...all can kill • Human disturbances - changing the ecosystem ~ deforestation, waste dumping, killing off predators

  8. DDF - only become limiting when the pop. density reaches a certain level • DIF - affect all pops. similarly regardless of pop. size • Through a combination of all of these factors, populations can vary from being in balance, to being way out of balance.

  9. Interaction in CommunitiesC-5-2

  10. There are many different ways species can interact with each other within their communities...

  11. Interactions • Competition • species have similar needs and compete for survival • Predation • one org. eats another • back and forth adjustment between the 2 results in coevolution • ex: the faster the prey gets, the faster the predator gets and vice versa

  12. Interactions • Symbiosis - relationship where 2 species live closely together. 3 types: a.) Mutualism - both species benefit ex: flowers and insects b.) Commensalism - one benefits, the other is neither helped or harmed ex: barnacles on a whale c.) Parasitism - one org. lives on another and the host is harmed ex: tapeworms in mammals

  13. Shaping CommunitiesC-5-3

  14. Habitat • area in which an org. lives

  15. Niche - all conditions in which an org. lives and how it uses those conditions • type of food eaten • place in the food web • temp. in which they survive • reproduction style • Fundamental niche - where a species could live • Realized niche - where a species actually lives

  16. No two species will share the same niche in the same habitat!

  17. Competitive exclusion principle • no 2 species can occupy the same niche in the same habitat at the same time • this would result in the elimination of one of the species

  18. keystone species • these are critical to the ecosystem because they affect the survival and number of many other species in their community • Ex. Sea otters

  19. Ex: sea otters: • sea urchins eat kelp - sea otters eat sea urchins • when sea otters are over hunted, too much kelp gets eaten by urchins - all other species that use the kelp to live in lose their home. • sea otters are critical to the survival of the ecosystem

  20. Summary • The more species in a community, the better • It will recover from disasters. • The predators help insure that no one species takes over. • More biodiversity = better resiliency

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