Topic 3.1: Introducing biodiversity
What is Biodiversity?
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Biodiversity is the number and variety of species, ecological systems, and the genetic variability they contain on the entire planet.
Biological diversity is organized at many levels, with 3 types:
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Diversity distribution is greatest near the equator and becomes increasingly lower as you move away from it. Notice the direct connection between biodiversity distribution, biome distribution and the tricellular model (see topic 2.4) *red = high diversity
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Why Biodiversity matters
Biodiversity matters because it:
Further reading links:
Why conserve biodiversity- Colorado Natural Heritage Program Why Biodiversity Matters: In the Grip of Global Extinction- Nature Serve Why Biodiversity matters? Who Cares? - Global Issues Biodiversity and Human Health - WHO Putting the Bio in Biodiversity - HowStuffWorks |
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Types of Biodiversity
Species diversitySpecies diversity = total number of species on the planet.
Australia contains some of the most unique organisms on earth, they are found no where else. The number is relatively low compared to the Amazon, but they exist no where else, making them an important part of species diversity. |
Genetic DiversityGenetic diversity = the gene pool of a specific population.
Genes are responsible for the traits exhibited by organisms. Declining population sizes ultimately decrease unique genetic variants. The removal of the diversity makes the population more vulnerable to extinction. Genetic variation allows species to evolve in response to diseases, predators, parasites, pollution, and climate change. Examples of issues when genetic diversity (population size) gets too small:
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Habitat diversityHabitat diversity = the range of habitats within an ecosystem.
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Biodiversity and Ecosystem Health
High Biodiversity often indicates resilience and stability as well as a healthy ecosystem.
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High biodiversity does NOT always equal health (at least all the time)
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Pro
Biodiversity and Productivity- Science Daily Biodiversity Productivity Relationship in Forests - Science Journal Biodiversity, productivity, and nutrient cycle relationships- NCBI Issues in Ecology - Ecological Society in America Biodiversity Critical to Maintaining Healthy Ecosystems - USGS |
Con
Diversity Stability Debate- Nature Species Redundancy- contradiction or not?- University of Minnesota One, two, skip a few? - Oceanbites Species Richness Does Not Equal Biodiversity- Wildlife in the Balance Are Numbers a measure of Ecosystem health - Yale Environment |
Biodiversity Indexes & data
Biodiversity indices allow us to compare two similar ecosystems together or two communities within an ecosystem. They generate numbers which allow for "measuring" diversity. It is not an exact measurement, but rather a subjective judgement using a combination of factors.
Some Indexes to measure diversity include: Simpson's diversity index, Shannon-Weiner Index, Biotic Index
Some Indexes to measure diversity include: Simpson's diversity index, Shannon-Weiner Index, Biotic Index
Simpson's Diversity (D)D is a measure of dominance, so as D increases, diversity (in the sense of evenness) decreases.
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Shannon- Weiner Diversity Index (H)
Allows for the measurement of evenness as well: E = H/ Hmax
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Biotic Index (BI)The biotic index assigns different levels of tolerance to pollution to the different types of organisms.
A higher the BI = presence of more sensitive species, indicating an unpolluted environment.
A lower BI = the presence the absence of sensitive species, and abundance of pollution tolerant species, indicating a polluted environment. |
Biodiversity Hotspots
Hotspots are regions with a high level of biodiversity that is under threat from human activity. They usually have high numbers of endemic species (species only found in one place). Roughly 30 areas have been recognized as hotspots (contain ~60% of the world’s species).
Identifiers of hotspots:
Why Hotspots Matter Maintaining Large scale biodiversity is crucial |
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