Effects of Evolution and Migration on Ecosystems

Swarming Bees and Migration

  • Swarms of bees migrate to relocate or find a place to establish their hive.
  • Insects migrate to follow resources needed for survival.
  • Migration affects diversity in an ecosystem or biome.

Biodiversity: Analyzing Effects of Local Evolution or Migration

  • Analyze the effects of local evolution or migration on an ecosystem.
  • Predict the impact of removing or adding organisms to a food chain.
  • Explain how changes in biodiversity impact an ecosystem.

Diversity in Ecosystems

  • Four main types of diversity:
    • Genetic diversity
    • Ecosystem diversity

Genetic Diversity

  • Refers to the amount of genes within a gene pool.
  • Gene pool: all the genes that organisms possess in an area.
  • Isolated island example: very little genetic diversity due to interbreeding.
  • Area with frequent organism movement: more genes, higher genetic diversity.
  • More genetic diversity leads to more stability in reproduction.

Ecosystem Diversity

  • Refers to the number of different habitats within an ecosystem.
  • Can range from very few to several habitats.

Species Diversity

  • The different types of fish or coral, etc, living in an area.

Regional Diversity

  • Variety of landscapes within an ecosystem.
  • Similar to ecological habitats.

Biodiversity

  • Definition: the diverse range of organisms, genes, and ecosystems found in the biosphere.
  • Rainforest: high biodiversity due to many different types of organisms.
  • South Pole/Antarctica: low biodiversity due to few types of organisms.
  • Affected by:
    • Evolution
    • Migration
    • Human impact: deforestation reduces biodiversity.
    • Exotic or invasive species: compete with native species, reducing biodiversity.

Evolution in Ecosystems

  • Two types:
    • Macroevolution
    • Microevolution

Macroevolution

  • Evolution of an entire family of organisms in relation to all other organisms.
  • Example: birds evolving as a group, possibly from dinosaurs, undergoing large changes.

Microevolution

  • Smaller changes to smaller groups of organisms within a single population.
  • Shorter timeline.
  • Increases or decreases the survival rate of organisms and increases biodiversity.
  • Random mutations can be advantageous or disadvantageous.
  • Advantageous mutations: survive longer, reproduce more, pass on genes.
  • Disadvantageous mutations: die quickly, do not pass on genes.
  • Increases biodiversity by helping to create more species that can fill niches.
  • Different types of flowers with small differences filling different niches.

Migration in Ecosystems

  • Movement of organisms from one location to another.
  • Geese flying in formation to conserve energy.
  • Affected by:
    • Food supply
    • Water supply
    • Climate change
  • Birds migrate south for food, not just to avoid cold.
  • Monarch butterfly: special generation lives several months to migrate 1,800 miles from North America to Mexico for breeding; subsequent generations relay back North each living only a few weeks.
  • Migration causes temporary or permanent appearance of new organisms.
  • Can lead to a loss of native species due to competition.
  • Exotic or invasive species can displace organisms.
  • Killer bees (Africanized bees) displace native honeybees.
  • Stocked trout compete with native fish populations.

Getting Real with Science: Africanized Bees

  • Mixture of African bee and native honeybee, bred for increased honey production.
  • Escaped laboratory, interbred with native bees.
  • Spread throughout Central and North America.
  • Dangerous due to swarming behavior.

Thinking Ahead: Food Webs and Food Chains

  • Food Web: Krill eaten by several species, squid also eaten by a couple species.
  • Food Chain Example: Cheese -> Mouse -> Cat
  • Removing the cat: mouse population skyrockets, cheese runs out.
  • Removing or adding organism to an ecosystem that results in considerable damage and consequences.

Biodiversity Section 2

  • Predict the impact of removing or adding organisms to a food chain.
  • Explain how changes in biodiversity impact an ecosystem.

Food Chains

  • Definition: a single pathway from producer to consumer.
  • Example: vegetation -> grasshopper/locust -> mouse -> snake.

Food Webs

  • Shows the integrated pathways of feeding in an ecosystem, all feeding relationships.
  • Multiple species eat Krill, and then those species are eaten by other species.

Organism Changes in Food Webs

  • Losing an organism can cause decrease or increase of other organisms in their populations.
  • Removing Krill: squid and anchovy populations decrease, eventually affecting higher-level consumers.
  • Removing top-level consumer: squid and anchovy populations increase, harming krill population, eventually leading to squid and anchovy population decline.
  • Removing middle organism (anchovies): organisms that eat them struggle, and the populations they prey on decrease.
  • Removing an organism causes severe changes to the balance of the ecosystem.

Reintroducing an Organism

  • Reestablishes a niche, causing competitive exclusion.
  • Squid removed and reintroduced: brings ecosystem back to balance, controlling krill population to equilibrate ecological pressures.

Adding a New Organism

  • Can lead to competitive exclusion.
  • Adding orca (eats squid): competition for squid, decreasing squid population.

Getting Real with Science: Reintroduction of Species

  • California condor: limited success.
  • Mexican gray wolf: ongoing efforts.

Thinking Ahead: Biodiversity, Stability, and Productivity

  • Rainforest: great biodiversity, many organisms, diverse niches.
  • Arctic Tundra: less biodiversity, fewer organisms adapted to climate.
  • Less biodiversity: less stable ecosystem, missing niches, more volatile food web or resource chain.

Biodiversity Section 3

  • Explain how changes in biodiversity impact an ecosystem.

Biodiversity and Ecosystem Stability

  • Increase in biodiversity: increases ecosystem stability.
  • Increases in Productivity: more food for herbivores, which can then feed more organisms up the food chain.
  • Very productive ecosystems: such as rainforests.
  • Goal:More biodiversity is always preferred.

Changes in Biodiversity

  • Decrease in biodiversity: decreases ecosystem stability.
  • If there is not an organism that can fill a lost niche the ecosystem will develop gaps.
  • Decreases its productivity
  • Less vegetation = less energy production.
  • Arctic Tundra: very little biodiversity compared to Rainforest due to climate restrictions on vegetation growth.

Getting Real with Science: Rainforest Biodiversity

  • More than half of the world's 10,000,000 species are found in the rainforest.
  • Approximately 137 species are lost daily due to deforestation.

Summary

  • Evolution impacts an ecosystem by increasing its biodiversity.
  • Migration can increase the biodiversity of an ecosystem but can also have negative effects on the of an invasive.
  • Removing, adding, or reintroducing organisms can cause an increase or decrease in the numbers of other organisms on the food chain.
  • Increasing biodiversity will increase the stability and productivity of an ecosystem while decreasing the biodiversity will have the opposite effect.