Unformatted text preview: Bio Pl 2400 Bio Pl 2400 Part III Biodiversity
Measuring Diversity and Extinction Measuring Biodiversity Measuring Biodiversity Genetic Diversity Species Diversity Ecosystem Diversity Measuring Species Diversity Measuring Species Diversity Species Richness number of Species in an Area species/area curve Species Abundance relative numbers of species/relative abundance Taxonomic Diversity taxonomic relationships among species Community Structure Community Structure Structure or spatial distribution of individuals or populations Large communities have variable vegetation patches, with large transition zones between ecosystems. edges can have different combinations of species than either adjacent patch Edges are increasing due to fragmentation Measuring Species Diversity Measuring Species Diversity Generally see greater diversity in equatorial latitudes, decline toward polesincrease with increase sunlight, decreasing elevation In aquatic ecosystems greater diversity with depth, down to about 2000 meters, then decline Keystone and indicator species are critical The most Species–rich environments are: The most Species–rich environments are: Tropical Rainforests Coral reefs The deep sea Large tropical lakes These areas tend to have high species richness, but low abundance Types of species in an area Types of species in an area Native species Nonnative species Keystone species Indicator species Indicator Species Indicator Species Early warning of damage to an ecosystem Birds tend to respond quickly to change Decline in songbird population indicative of habitat loss Decline in trout species, amphibians indicative of water pollution Keystone Species Keystone Species Play pivotal role in structure and function of an ecosystem Interaction with other species effect health and survival of these species Process materials out of proportion to numbers or biomass Keystone Species Keystone Species Specific pollinators of flowering plant species bees, hummingbirds, etc. Predation by carnivores keeping populations in check Recycling of nutrients dung beetles recycling animal waste Habitat modificationElephants uproot trees, open up grassland; beaver dams, Measuring Extinction Rates Measuring Extinction Rates Species/area curves 90% loss in area results in 50% decline in species Minimum Viable Population estimates Minimum Dynamic Area Population Viability analysis Risk assesment analysis to determine persistance of a population Minimum Viable Population Minimum Viable Population Smallest number of individuals necessary to ensure population survival in a region for a specific time period Most indicate a few thousand individuals are necessary for survival beyond a few decades Minimum Dynamic Area Minimum Dynamic Area Minimum area of suitable habitat needed to maintain MVP Most small animals require 100—1000 square km 50 grizzly bears 49,000 square km Population Viability Analysis Population Viability Analysis Risk assessment model predicting viability of a population for a number of generations Based on: current resource needs and habitat conditions Genetic variability Reproduction rate Interaction with other species Types of Extinction Types of Extinction Local Extinction Species no longer found in an area, but still exists globally Ecological Extinction so few remaining members of a species exist, it no longer plays a role in ecosystem Biological Extinction Species no longer found Species Prone to Extinction Species Prone to Extinction Low reproductive rate Specialized niche Narrow distribution Fixed migratory patterns Rare Commercially Valuable Require large territories Factors Leading to Decline in Factors Leading to Decline in Species Environmental Stress Large Environmental Disturbance Extreme Environmental Conditions Resource Limitations Invasive nonnative species Geographic Isolation ...
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- Fall '08
- Measuring Species Diversity