Chapter 4: Biodiversity and Evolution

• Species richness - number of different species in the ecosystem
• Species evenness - relative abundance of individuals among the different species in the ecosystem
• How could you determine species richness? - count the number of species
• What abiotic factors in an ecosystem could result in high species richness? - phosphorus, sunlight, precipitation, temperature, nitrogen
• Why can’t species richness alone be used to evaluate the health of an ecosystem? - even if you have a large amount of species, there could still be an imbalance, could have invasive species

invasive species - species that do not belong in an ecosystem

Species Diversity Lab Quickwrite Questions

• What would be a testable hypothesis for this lab investigation? - BLS has low biodiversity compared to other nearby ecosystems
• Explain why the presence and relative abundance of different species may vary between two nearby areas, even if the areas appear similar. - there may be subtle differences between the two areas such as different vegetation, or there could be human-made changes that affect the ecosystem

Human Effects on Biodiversity

• How is the image of the red fox eating the Arctic fox related to climate change? - foxes’ normal prey died off, Arctic fox is exposed without the snow and ice

• How will biodiversity in the arctic respond to climate change? - melting ice and snow causes disruption in the food web

  • What is the name for something that brings about change in an ecosystem? - environmental pressure

• How does biodiversity on earth respond to environmental change? - adapt, migrate, or die

  • What determines which of these outcomes occurs? - time and rate of change

• What can lead to reproductive isolation? - geographic isolation

• How can human activities degrade biodiversity? - hastening the extinction of species, disrupt habitats

• How do populations evolve? - mutations and natural selection

• Biodiversity - variety in the earth’s species

• Species - set of individuals who can mate and produce fertile offspring

• What are the different types of diversity? - functional, ecological, genetic, species

  Prelab Questions

  1. In order to support life, you need access to fresh water all year, sunlight, and soil.
  2. The biodiversity will be lower because there are fewer species counted.
  3. 73
  4. a.

• b. 1.774

5a. 4.290

b. 0.413

Adapt, Migrate, or Die

• Invasive species - a species that’s not supposed to be in the ecosystem, typically transported by humans
  • How do invasive species disrupt ecosystems? - they outcompete native species
• Keystone species - a species upon which all of the other species rely
• What happened to the passenger pigeon - once the most abundant bird in North American with 2-3 billion individuals are now extinct
• HIPPCO - Habitat destruction, invasive species, pollution, population (growing human population), climate change, overexploitation
  • To what does HIPPCO refer? - how humans cause species to go extinct in order of importance
  • overexploitation - hunting, illegal wildlife trade, poaching

Indicator species - provide early warning of damage to a community and help monitor environmental quality

Evolution

• How did humans become so powerful? - opposable thumbs, complex brains, walk upright
• How has climate change on an ice age level affected species diversity? - decreased it because species that are better adapted to these conditions survive, species divergence, environmental pressures on a slow timescale makes adaption easier
• Can species thought to be extinct be discovered? - haven’t discovered everything, could discover an isolated population, islands
• How do populations evolve? - mutations in genes which enhance individuals’ ability to produce offspring with these traits
• How does Earth’s life change over time? - evolution
  • Evolution - change in the characteristics of a species over several generations and relies on the process of natural selection
  • Biological evolution - how the earth’s life changes over time through changes in the genetic characteristics of a populations
• fossils - physical evidence of ancient organisms which reveal what their external structures looked like
• fossil record - entire body of fossil evidence
• How do plate tectonics affect evolution and the location of life on earth? - locations of continents and oceans have shifted through geologic time, species physically move, adapt, or form new species through natural selection
• How do catastrophes affect natural selection? - temperatures warming too quickly makes it hard for species to adapt
• What were the outcomes of your measurements of the species diversity of the Boston Latin Schoolyard? - not diverse
• What did you learn about species richness and evenness? - more rich in the undisturbed area, neither was very even,

What are some major takeaways? - humans have a significant impact on biodiversity

Species Diversity and Species Roles

• Niche - the specific ecological role that a species plays
• What are the 5 important roles that a species may play? - native, nonnative, indicator, keystone, foundation
• generalist species - broad niche: wide range of tolerance
• specialist species - narrow niche: narrow range of tolerance

ecological niche - everything that affects survival and reproduction

Affecting Biodiversity

• How has life on Earth changed over time? - plate tectonics, asteroids, organisms have changed and died out, >95% of all life has gone extinct
• How do we know that life on earth has changed? - fossil evidence
• How do biotic and abiotic factors drive evolution? - environmental pressures, biotic: genes and mutations bring about change through adaptation
• Is life still evolving now? - yes
• genetic resistance - ability of one or more members of a population to resist a chemical designed to kill it
• speciation - one species splits into two or more
• How does geographic isolation affect evolution? - different environmental pressures results in different adaptations
• reproductive isolation - mutations and natural selection leads to inability to produce viable offspring when members of two different populations mate
• divergent evolution - two species diverge from a common ancestor
• convergent evolution - similar features among species without a common ancestor
• coevolution - two species evolve together and affect each other’s evolution
• What determines earth’s biodiversity? - balance between formation of new species and extinction of existing species
• How can human activities decrease biodiversity? - causing extinction of many species, destroying habitats needed for the development of new species