Unit 2: Biodiversity

• Biodiversity is the diversity of life forms in an ecosystem that is measured on three different levels: ecosystem, species, and genetic
• Level 1: Ecosystem Biodiversity

  • The different number of habitats available in a given area
  • Ex. An ocean, the sand, a forest, a desert joined together
• Level 2: Species Diversity

  • The different number of species in an ecosystem and the balances or evenness of the population sizes of all species in the ecosystem
• Level 3: Genetic Diversity

  • The difference between the genes of each individual within a population
  • Ex. A population of squirrels have different genes
• Higher biodiversity = Higher ecosystem/population health
• Species diversity can be measured in what?

  Richness and evenness
• Species Richness (r)

  • The total number of different species found in an ecosystem
  • Higher richness is generally a sign of a healthy ecosystem because more species can be supported, meaning the resources are good
  • However, it isn't the sole factor
• Species Evenness

  • The measure of how all of the individual organisms in an ecosystem are balanced between different species
  • Evenness indicates if there is one or more dominant species, or if population sizes are balanced
• Higher richness = healthier ecosystem but evenness should be considered if the richness is the same
• Based on the image, which community is healthier?

  Community 1

  
• Genetic diversity: In Depth

  • A measure of how different the genomes (set of genes) are of the individuals within a population of a given species
  • Remember! All populations have genetic diversity
• How does Genetic Diversity occur

  • There is genetic diversity in all populations because of random mutations when copying DNA and recombination of chromosomes in sex cells of parents
• The more genetic diversity in a population, the better the population can respond to environmental stressors like droughts, disease, or famine
• More genetic diversity = higher chance that some of the individuals in a population have traits that allow them to survive the environmental stressor
• Bottleneck Event

  • A disturbance that drastically reduces population size and kills organisms regardless of genomes
  • The surviving population is smaller and because individuals are divided randomly, it doesn't represent the genetic diversity of the original population

  
• • Bottleneck events reduce genetic diversity
  • Because the population is smaller and less genetically diverse, it's even more vulnerable to future environmental disturbances
• Inbreeding Depression

  • Inbreeding is when organisms mate with closely related "family" members
  • This leads to a higher chance of offspring having harmful genetic mutations because they're getting similar genotypes from parents
  • Smaller populations are more likely to inbreed because of the difficulty of finding a non-related mate
• Example: Inbreeding Depression

  • Florida Panther population decreased to 30 in the 1990s due to hunting and habitat loss, which led to inbreeding
  • Inbreeding depression = kinked tails, heart defects, low sperm count, undescended testicles
  • Scientists bought Texas Pumas (related species) to reintroduce genetic diversity
• Ecosystem Resilience

  • Resilience is the ability of an ecosystem to return to its original conditions after a major disturbance (wind storm, fire, flood, etc)
• Just like genetic diversity helps populations recover, species diversity helps ecosystems recover. Higher species diversity = higher ecosystem resilience
• Species Diversity and Ecosystem Resilience

  • More plants can repopulate disturbed ground, anchor soil, and provide food and shelter for animal species
• Ecosystem Services are goods that come from natural resources or services/functions that ecosystems carry out that have measurable economic/financial value to humans
• Provisioning Services

  • Goods taken directly from ecosystems or made from natural resources (wood, paper, food)
• Regulating Services

  • Natural ecosystems regulate climate/air quality, thus reducing storm damage and healthcare costs
• Supporting Services

  • Natural ecosystems support processes we do ourselves, making them cheaper and easier
  • Bees pollinating crops
• Cultural Services

  • Money generated by recreation (parks, camping, tours) or scientific knowledge
• Human Impacts: Ecosystem Services

  • Human activities disrupt the ability of ecosystems to function, which decreases the value of ecosystem services they provide
  • This leads to ecological (natural) and economic (money-based) Consequences
  • Ex. clearing land for agriculture/cities removes trees that store CO2, resulting in more CO2 in the atmosphere, leading to more climate change, then leading to storm damage and crop failure
  • Overfishing leads to short-term profit and long-term fish population decrease, lower fishing sales in the future
• Ecological Impacts >>> Climate change and CO2 and less fishing

  Economic Impacts >>> Storm damage, crop failure, less fishing jobs and sales
• Provisioning Services

  1. Goods/products directly provided to humans for sale/use by ecosystems
  2. Fish, hunting animals, lumber, naturally-grown foods
  3. Goods/products that are made from natural that ecosystems provide
  4. Paper (lumber), medicine (plants), rubber
• Regulating Services

  • Benefits provided by ecosystem processes that moderate natural conditions like climate and air quality
  • Example: Trees in a forest store CO2 which reduces rate of climate change and lessens damage caused by rising sea levels and reduces crop failure from drough
• Example: Regulating Services

  • Trees filter air by absorbing air pollutants which reduces health care costs for treating diseases like asthma and bronchitis

  Human Impacts

  • Deforestation reduces the amount of trees that store CO2
• Supporting Services

  • Natural ecosystems support processes we do ourselves, making them less costly and easier
  • Example: Wetland plant roots filter pollutants, leading to cleaner groundwater that we don't have to pay as much to purify with expensive water treatment plants
• Example: Supporting Services

  • Bees and other pollinators pollinate our crops leading to higher productivity, more crop production, and cheaper crops due to the extra production

  Human Impacts

  • Disrupting pollinator habitats and filling wetlands for development of cities, leading to expensive water treatments
• Cultural Services

  • Revenue from recreational activities (hunting/fishing licenses, park fees, tourism-related spending) and profits from scientific discoveries made in ecosystem (health/agriculture/educational/knowledge)
  • Example: Beautiful landscapes draw tourists who pay to enter parks, spend money at local stores/restaurants, or camping fees
  • Example: Fisherman pay for fishing licenses to catch fish in clean waters
• Example: Cultural Services

  • Scientists learn about plant compounds that can lead to creation of new medicines which are sold for profit
• Human Impacts: Cultural Services

  • Deforestation -- tourists won't go to destroyed parks
  • Pollution -- fisherman won't want to fish in unclean water
  • Urbanization -- decreases amount of people who go to see the landscape
• Theory of Island Biogeography

  • The study of ecological relationships and community structure on islands
  • Islands can be actual islands in a body of water or figurative islands such as central park in New York City or national parks (surrounded by human land)
• Central Park is a figurative island because it is surrounded by human-developed land that is inhabitable for species
• Rules of Island Biogeography

  • Larger Islands support more total species
  • Islands closer to the "mainland" support more species
• "Larger Islands Support More Total Species"

  • The larger the island, the greater the ecosystem diversity
  • Greater ecosystem diversity = more food and habitat resources
  • More niches or "roles" organisms can play in the ecosystem