The Living World: Biodiversity: Chapters 4, 5-2, 9, 10-5, 11-1, 11-2, & 11-6

• Biodiversity is the level of life forms in an ecosystem (3 levels)

  • Higher Biodiversity = higher ecosystem health

• Ecosystem Diversity - # of different habitats in an area

• Species Diversity - # of different species and balance/evenness of all species

  • Higher species diversity = higher ecosystem resilience

• Genetic Diversity - How different the genes of individuals are within the same species

  • More genetic diversity, population more tolerant to stress

• Richness (r) - total number of different species found in an ecosystem

  • High (r) is good sign of ecosystem health

• Evenness - Measures balance between different species

  • Indicates one or two dominant species, or populations are well balanced

• Bottleneck Event - Kills lots of a population (something like a fire)

  • Reduces genetic diversity & population size

• Inbreeding Depression

  • Harmful genes are caused when organisms mate with family members

  • Usually occurs in smaller populations

• Ecosystem Resilience - Ability for an ecosystem to return to its original condition

  • High species diversity = higher ecosystem resilience

Island Biography:

• Doesn’t need to be an island (think centeral park in NY)

• Larger islands = more species diversity / richness

  • Larger area = more ecosystems (Ecosystem Diversity)

  • More resilient (tolerant) to stress

  • Lower extinction rate

• Closer to mainland = more species diversity / richness

  • Easier for species to migrate (swim/fly)

  • More frequent migration

  • Inverse Relationship: Distance increases, species diversity decreases

• Islands are limited in space & resources

  • More pressure for species to adapt

  • Creates more niches

  • Ex: Birds having different beak sizes to eat different foods

Ecological Tolerance:

• Is the range of temperature, pH, or sunlight that an organism can endure before death

• Species and Individual organisms all have different tolerances (even in one species)

  • Due to genetic biodiversity

• In a stress vs number of organisms graph:

  • Represented as a bell curve

  • Optimum range is where that organism will survive

  • Zone of phycological stress is a warning area

  • Zone of intolerance is where the organism will probably die

• Connect human activities to ecological range of tolerance

  • Connect with climate change

  • Too much rise in temperature, organism cant take it and die

• Physiological Stresses: suffocation, thermal shock, lack of water/food/nutrients/oxygen

  • Fish cant absorb oxygen due to warm temps

  • Plant roots cant absorb enough water from soil

Natural Disturbances:

• Change in energy, displace in organisms, destruction, & removal of resources

• Ex: Tornadoes, huricanes, asteroids, forest fires, drought

• Three timeframes: Periodic, episodic, or random

  • Periodic: Occurs with regular frequency (dry-wet seasons)

  • Episodic: Irregular frequency (more fires in summer)

  • Random: No regular frequency (volcanoes, earthquakes)

• Natural Climate Change: Earth’s climate changes over time naturally

  • Like: Ice ages or other warm periods

  • Usually follows by variation in carbon dioxide

• Ex: Sea level rise causes estuary habitats (like mangroves) to be flooded

• Migration: wildlife will migrate to follow resources (like food and water)

Adaptations / Genetic Diversity:

• Mutations: Random changes in DNA

• Breeding could cause crossing of chromosomes, creating new genes, then traits

• Adaptation: a new trait that helps an organism survive

• Natural Selection: organisms that are better adapted, will survive

• Environment determines which traits are adaptations

  • Ex: Tall basketball players will be good, but bad in marathons

• Adaptations are very slow

  • Rapid changes / stressors, more will die

Ecological Succession:

• are a series of predictable growth

• Primary Succession: starts from bare rock. Moss & lichen will break down rock into soil

• Secondary Succession: Soil already exists, but a disturbance causes plant life to be cleared out

  • Pioneer species will move in quickly here, then get replaced by generalist

4-4 How Do Speciation, Extinction, and Human Activities Affect Biodiversity?

• Speciation: Natural selection can lead to an entirely new species

  • One species can split into two or more

  • Common changes are in color (like skin color of poison dart frogs)

• Geographic isolation: Type of speciation happens when a species is separated by a barrier

• Reproductive isolation: mutations during reproduction cause changes in a species’ genes.

• Artificial Selection & Genetic Engineering are caused by humans

• Extinction: an entire species ceases to exist

  • When environmental conditions change quickly, species must adapt, migrate, or die.

• Endemic species are found in one area

  • Usually a lot more vulnerable to extinction

  • Species that live on islands or other specific areas (like rain forests)

  • Ex: golden toad amphibian (frog)

• Background extinction rate: Earth’s species disappearing during history

  • Low number like 0.0001%

• Mass extinction: event with significant rise in background extinction rate

  • High number like 25-95%

  • Fossils & Geological evidence confirms past 3 - 5 mass extinctions

  • Happens every 20 - 60 million years

4-5 What is Species Diversity and Why is It Important?

• Species Diversity: variety and number of a species in a community

• Species Richness: Number of species in an area

• Species Evenness: Proportion of species in an area

  • High species evenness indicates a relatively balanced distribution of species

  • Low evenness suggests that a few species dominate the community

• Species rise ecosystems tend to be productive and sustainable

  • Think temperate rain forest

  • Usually more tolerant / resistant to external factors (Like droughts)

4-6 What Roles Do Species Play in Ecosystems?

• Ecological Niche / Niche: Role a species plays in an ecosystem

  • Pattern of living

• Habitat: Place where a species lives

• Specialist Species: Has narrow, specific niches

  • Like living in one type of habitat, or eating one type of food

  • Only tolerates a specific climate, or other environmental condition

  • Like the Giant Panda

• Native Species: Species that live and thrive in a particular ecosystem.

• Nonnative Species: Often not threatening, but sometimes can be threatening like invasive species

• Indicator Species: Provides early warnings that ecosystems are failing

• Keystone Species: Species who have large / critical roles in a ecosystem

  • Like pollinators

  • Loss of a keystone species can be sarcastic, since they heavily impact ecosystem services.

• Top Predatator Keystone Species: Regulate populations of other species