Includes: ecosystem diversity, species diversity, and genetic diversity
Diversity of genes Chihuahuas, Greyhound and Newfies are all dogs—but they're not the same because their genes are different. Chihuahua Greyhound Newfoundland
Diversity of species Hoary Bat Kahuli Iwi
Diversity of ecosystems Tropical Rain Forest tiaga Desert
Biodiversity has Intrinsic Value Source: Burmbaugh © AMNH-CBC (value in and of itself)
Biodiversity also has Utilitarian Value . Utilitarian values include: Goods Services Information
What do we get from biodiversity? Oxygen Food Clean Water Medicines Beauty Ideas/Inspiration
Biodiversity hotspots - areas with a high concentration of endemic species, experiencing rapid habitat loss
Threatened (vulnerable) species: Still abundant in its natural range but is likely to become endangered in the near future. Endangered species: So few individual survivors that it could soon become extinct.
Current State of Biodiversity 1.4 million described species….perhaps 10 million in total??? Background extinction rate (rate of extinction in the absence of human activities): In one year, a species has a one in ten million chance of going extinct
Mass extinction – loss of large number of species usually due to catastrophic volcanic eruption or meteor impact very rare (5 times in 3 billion years) Current rate of extinction???
Should we be concerned about biodiversity? What we know: The Earth is losing species at an alarming rate Perhaps as many as 3 species per hour are going extinct and 20,000 extinctions occur each year. when species of plants and animals go extinct, many other species are affected.
Core Case Study: The Passenger Pigeon: Gone Forever Once the most numerous bird on earth. In 1858, Passenger Pigeon hunting became a big business. By 1900 they became extinct from over-harvest and habitat loss.
Passenger Pigeon: Hunted to extinction Former population about 6 billion animals
Carolina Parakeet: extinct Habitat loss (forest clearing), over hunted (for feathers and by farmers who considered them a pest)
Ivory-Billed Woodpecker: Critically endangered, probably extinct Once found in southern hardwood swamps and pine forests Comparison of ivory-billed (top) and pileated woodpecker below)
Threats to Species: Remember H.I.P.P.C.O. H.I.P.P.C.O. – the most important causes of extinction: Habitat destruction, degradation, and fragmentation Invasive (nonnative) species Population and resource use growth Pollution Climate change Overexploitation
Extinctions Can Be Natural But Sometimes The Rate Increase Sharply Local Extinction (Extirpation): A species is no longer found in an area it once inhabited but is still found elsewhere in the world. Typically the result of habitat destruction or overhunting and affects more than one species. Examples: wolf and mountain lion in Maine Extinction (Global extinction) is Forever.
Characteristics of Species That Are Prone to Extinction These characteristics make survival harder when environmental conditions change or when humans interfere.
Endemic Species Only live in one specific place (geographic location or habitat type – usually islands) Very vulnerable to extinction as a result of habitat loss or degradation.
Habitat destruction and fragmentation Fragmentation- breaking large areas of habitat into smaller, isolated patches
Golden lion tamarin
Changes in housing density in Southern Maine Source: http://www. whrc
Edge Effects-negative impacts adjacent to habitat boundaries Forest Edges: -more sunlight -drying -higher winds -higher tree mortality -more invasive species -more predators
Core area – part of a patch not impacted by edge effects Edge area Core area Core area – part of a patch not impacted by edge effects Patch size is not always the best predictor of patch quality
Introduced Species Humans are constantly moving species to new locations Sometimes this is done deliberately, sometimes by accident Often the most serious impacts are on islands due to: -low species diversity -few native predators so many species have not developed anti-predator defenses (or resistance to diseases) https://www.youtube.com/watch?v=mUssO68D2eM
Characteristics of Invasive Species -pioneer species -high dispersion rates -found in disturbed habitats…..but some can invade undisturbed areas Why are invasives successful? -Often have no diseases, nothing that will eat them, no parasites -outcompete native species for resources
Introduced diseases – exploit lack of evolved resistance Dutch elm disease – American elm Chestnut blight – American chestnut avian malaria – Hawaiian birds Rinderpest – African ungulates chytrid fungus – amphibians
Net result of invasive species Homogenize ecological communities around the world Drive native species to extinction
Exploitation and overharvest Direct exploitation for food Overfishing Bycatch Bushmeat = harvest of wild animals for food Can be sustainable but is often not Threatens many species of primates and other mammals as well as other wildlife Primarily a concern when it is obtained illegally, commercially and/or unsustainably
Global Trade in Wildlife Birds, orchids, cactus, primates… Captured for gardens, pets, zoos…. Many species were driven to extinction before regulations were enacted to protect them (Ex: passenger pigeon, Carolina parakeet, sea mink…)
Climate change
Why do small populations go extinct? chance events that occur more frequently with small populations size failure to breed or survive failure to find a mate skewed sex ratio
Genetic effects at small population size Environmental effects – unpredictable events that reduce survival or reproduction droughts, floods, fires, storms Genetic effects at small population size inbreeding genetic drift random mutations
Extinction vortex – combination of genetic, environmental and demographic factors that drive a small population to extinction Heath Hen
Heath hen 1700 – throughout the northeast coast 1907 – 50 left on Martha’s Vineyard 1915 – 2000 birds 1916 – fire 1917 – goshawk invasion 1920’s – poultry disease 1927 – 13 birds, mostly males March 11, 1932 – last known sighting
Greater Prairie Chicken Conservation Status: Vulnerable
Populations that are very small suffer from lack of genetic diversity (for example cheetahs)
Maintenance of ecosystem function How many species can you safely remove? How do you ensure maximum productivity in managed or natural ecosystems?
More diverse ecosystems are more stable
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