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Speciation produces new types of organisms

Speciation produces new types of organisms. The process of generating new species A single species can generate multiple species Allopatric speciation = species formation due to physical separation of populations Can be separated by glaciers, rivers, mountains

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Speciation produces new types of organisms

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  1. Speciation produces new types of organisms • The process of generating new species • A single species can generate multiple species • Allopatric speciation = species formation due to physical separation of populations • Can be separated by glaciers, rivers, mountains • The main mode of species creation

  2. Another type of speciation • Sympatric speciation = species form from populations that become reproductively isolated within the same area

  3. Evolution generates biodiversity • Species = a population or group of populations whose members share characteristics and can freely breed with one another and produce fertile offspring • Population = a group of individuals of a species that live in the same area

  4. Biodiversity encompasses several levels • Humans are reducing Earth’s diversity of life • Biodiversity – sum total of all organisms in an area • Split into three specific levels: • Species diversity • Genetic diversity • Ecosystem diversity

  5. Species diversity • Species Diversity = the number or variety of species in the world or in a particular region • Richness = the number of species • Evenness or relative abundance = extent to which numbers of individuals of different species are equal or skewed • Speciation generates new species and adds to species richness • Extinction reduces species richness

  6. The taxonomy of species • Taxonomists = scientists who classify species • Physical appearance and genetics determines a species • Genera = related species are grouped together • Families = groups of genera • Every species has a two-part scientific name: genus and species

  7. Subspecies: the level below a species • Subspecies = populations of species that occur in different areas and differ slightly from each other • Divergence stops short of separating the species • Subspecies are denoted with a third part of the scientific name Siberian tiger = Panthera tigris altaica Bengal tiger = Panthera tigris tigris

  8. Genetic diversity • Encompasses the differences in DNA among individuals within species and populations • The raw material for adaptation to local conditions • Populations with higher genetic diversity can survive • They can cope with environmental change

  9. Ecosystem diversity • Ecosystem diversity = the number and variety of ecosystems

  10. Some groups contain more species than others • Species are not evenly distributed among taxonomic groups • Insects predominate over all other life-forms • 40% of all insects are beetles • Groups accumulate species by • Speciation and • Low rates of extinction

  11. Insects outnumber all other species

  12. Measuring biodiversity is not easy • Out of the estimated 3 - 100 million species on Earth, only 1.7 - 2 million species have been successfully catalogued • Very difficult to identify species • Many remote spots on Earth remain unexplored • Small organisms are easily overlooked • Many species look identical until thoroughly examined

  13. Biodiversity is unevenly distributed • Living things are distributed unevenly across Earth • Latitudinal gradient = species richness increases towards the equator Canada has 30 - 100 species of breeding birds, while Costa Rica has more than 600 species

  14. Latitudinal gradient has many causes • Climate stability, high plant productivity, and no glaciation • Tropical biomes support more species and show more species evenness • Diverse habitats increase species diversity

  15. Biodiversity losses and species extinction • Extinction = occurs when the last member of a species dies and the species ceases to exist • Extirpation = the disappearance of a particular population from a given area, but not the entire species globally • Can lead to extinction

  16. Striking gold in Costa Rica • Golden toads were discovered in 1964, in Monteverde • The mountainous cloud forest has a perfect climate for amphibians • Unfortunately, they became extinct within 25 years • Due to global warming’s drying effect on the forest

  17. Earth has had several mass extinctions • Background extinction rate = extinction usually occurs one species at a time • Mass extinction events = five events in Earth’s history that killed off massive numbers of species at once • 50-95% of all species went extinct at one time

  18. Species’ ranges can be severely restricted Some U.S. salamander species live on top of single mountains

  19. Earth has experienced five mass extinctions • In the past 440 million years, mass extinctions have eliminated at least 50% of all species

  20. The current mass extinction is human caused • The current global extinction rate is 100 to 1,000 times greater than the background rate • This rate will increase tenfold in future decades due to human population growth and resource consumption

  21. People have hunted species to extinction for millennia Extinctions followed human arrival on islands and continents

  22. Current extinction rates are higher than normal • The Red List= an updated list of species facing high risks of extinctions – created by the IUCN (International Union for Conservation of Nature and Natural Resources)

  23. Biodiversity loss is more than extinction • smaller species’ geographic ranges • Genetic, ecosystem, and species diversity are being lost. • Population shrinkage • The Living Planet Index summarizes trends in populations • Between 1970 and 2003, the Index fell by 30%

  24. Biodiversity loss has many causes • Four primary causes of population decline are: • Habitat alteration • Invasive species • Pollution • Overharvesting • Global climate change now is the fifth cause • Causes may act synergistically

  25. Habitat alteration causes biodiversity loss • The greatest cause of biodiversity loss • Farming simplifies communities • Grazing modifies the grassland structure and species composition • Clearing forests removes resources organisms need • Hydroelectric dams turn rivers into reservoirs upstream • Urbanization and suburban sprawl reduce natural communities • A few species (i.e., pigeons, rats) benefit from changing habitats

  26. Habitat alteration is primary cause Particularly in tropical rainforests, savannas, and tropical dry forests

  27. Invasive species cause biodiversity loss • Introduction of non-native species to new environments • Accidental: zebra mussels • Deliberate: food crops, cane toads, ornamentals, exotic pets • Island species are especially vulnerable • Invaders have no natural predators, competitors, or parasites • Cost billions of dollars in economic damage

  28. Pollution causes biodiversity loss • Harms organisms in many ways • Air pollution degrades forest ecosystems • Water pollution adversely affects fish and amphibians • Agricultural runoff harms terrestrial and aquatic species • The effects of oil and chemical spills on wildlife are dramatic and well known

  29. Overharvesting causes biodiversity loss • Most vulnerable are “K-selected” species: long-lived, small populations, few young • Examples: Atlantic gray whale, sharks, gorillas, Siberian Tiger Today the oceans contain only 10% of the large animals they once did

  30. Climate change causes biodiversity loss • Emissions of greenhouse gases warms temperatures • Modifies global weather patterns and increases the frequency of extreme weather events • Increases stress on populations and forces organisms to shift their geographic ranges • How are Yellowstone Grizzlies threatened by climate change?

  31. Warming has been the greatest in the Arctic The polar bear is on the red list

  32. Biodiversity loss has a variety of causes

  33. There are 34 global biodiversity hotspots 2.3% of the planet’s land surface contains 50% of the world’s plant species and 42% of all terrestrial vertebrate species

  34. Biodiversity provides free ecosystem services (pp 40 & 310-311 in text) • Provides food, shelter, fuel • Purifies air and water, and detoxifies wastes • Regulating climate • Generates and renews soil fertility and cycles nutrients • Pollinates plants and controls pests and disease • Maintains genetic resources (medicines, pets, ornamental species, genes for resistant crops) • Provides cultural and aesthetic benefits The annual value of just 17 ecosystem services = $16 - 54 trillion per year

  35. Biodiversity helps maintain ecosystem function • Biodiversity increases the stability and resilience of communities and ecosystems • Decreased biodiversity reduces a natural system’s ability to function and provide services to our society • The loss of a species affects ecosystems differently • If the species can be functionally replaced by others, it may make little difference • Extinction of a keystone species (one with strong impact out of proportion to its abundance) may cause other species to decline or disappear

  36. Biodiversity enhances food security • Wild strains provide disease resistance and are perennials • New potential food crops

  37. Some potential new food sources

  38. Organisms provide drugs and medicines • $150 billion in pharmaceutical sales each year from drugs originating from wild species

  39. Biodiversity generates economic benefits • Ecotourism: • Costa Rica: rainforests • Australia: Great Barrier Reef • Belize: reefs, caves, and rainforests • U.S. National Parks • Delicate balance between $ benefits and degradation of location

  40. People value and seek out nature • Biophilia = connections that humans subconsciously seek with life – term coined by E.O.Wilson

  41. Conservation biology responds to biodiversity loss • Conservation biology study of the factors that influence the loss, protection, and restoration of biodiversity

  42. Equilibrium theory of island biogeography:island’s species richness based on the island’s size and distance from the mainland • Fewer species colonize an island far from the mainland • Large islands have higher immigration rates and lower extinction rates

  43. The species-area curve • Large islands contain more species than small islands • They are easier to find and have lower extinction rates • They possess more habitats

  44. Fragmentation threatens biodiversity • Theory of Island Biogeography applies to National Parks which are islands of natural habitat • Smallest parks show more species loss than larger – too isolated to be recolonized

  45. Endangered Species Act (1973) (ESA) = forbids the government and private citizens from taking actions that destroy endangered species or their habitats • Successes include Bald Eagle • Controversy – limits private land use.

  46. ESA successes: • ESA SuccessePeregrine falcons, brown pelicans, bald eagles,

  47. The ESA is controversial Opponents feel that the ESA values endangered organisms more than the livelihood of people Private land use will be restricted if an endangered species is present “Shoot, shovel, and shut up” = landowners conceal the presence of endangered species on their land But, the ESA has stopped few development projects Habitat conservation plans and safe harbor agreements = landowners can harm species if they improve habitat for the species in other places

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