Today

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• Today
• finish biodiversity (Chapter 23)
• start conservation biology (Chapter 25)
• Wednesday
• conservation biology
• Friday
• quiz!
• conservation biology
• Monday
• historical biogeography (Chapter 24)
• Wednesday
• ecosystem management (outside reading)

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• Conservation Biology - a mission-oriented science
  that focuses on protecting and restoring
  biodiversity
• Biodiversity
• All forms of life
• All levels of organization (subpopulation to
  biosphere)
• All interactions among forms of life and the
  environment

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• Where is the biodiversity?
• Endemic species restricted to a small region
• isolated areas (islands, mountain ranges)
• product of unique habitat, climate features

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• Biodiversity hotspots - areas with a high
  concentration of endemic species, experiencing
  rapid habitat loss

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• Hotspots
• 1.4 of the land area
• 44 of vascular plant species
• 35 of terrestrial vertebrate species
• But
• 20 of the human population, which is
• growing at 1.8 per year (vs. 1.3 worldwide)
• each hotspot has already lost 70 of its
  vegetation

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• Current Status of Biodiversity
• 1.4 million described species, possibly 10
  million in total
• Background extinction rate rate of species loss
  in the absence of human activities
• fossil record species survive 1-10 million years
• one year one species has a 1 in 1-10 million
  chance of going extinct
• total 1 extinction per year

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• Mass extinction loss of large number of species
• usually due to catastrophic volcano or meteor
  impact
• very rare (5 times in 3 billion years)
• Current rate of extinction???

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• Some estimates for current rate
• 1 species per hour
• 1 million species total, so far
• 10 of all species so far
• 8.8 of all species
• 27,000 species per year
• 20 of neotropical plant species
• 100 to 10,000 times the background rate

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• Numbers of threatened/endagered species
• 5,188 vertebrates (9)
• 1,992 invertebrates (0.17)
• 8,321 plants (2.89)
• 2 lichens (0.02)
• Since 1600, 1000 species have gone extinct
  (probably many more)

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• Why do species go extinct?
• 2 separate processes
• Something causes a large population to decline.
• Small populations go extinct.

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• Causes of species declines
• Habitat destruction and fragmentation
• Introduced species
• Exploitation and overharvesting
• Pollution
• Climate change

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USA
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• Habitat destruction and fragmentation
• Fragmentation disruption of extensive habitats
  into small, isolated patches

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• Relaxation loss of species from isolated
  habitats over time

S
Area
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• Edge effects negative impacts adjacent to
  habitat boundaries
• Forest edges
• more sunlight
• drying
• high winds
• tree mortality
• invasive species
• more predators

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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

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• Introduced species
• Humans are constantly moving species between
  continents, islands
• deliberate or accidental
• Most serious impacts on islands
• low species diversity
• few native predators
• animals lack anti-predator defenses, resistance
  to diseases

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• Characteristics of invasive species
• pioneer species
• high dispersal rates
• found in disturbed habitats, but
• some can invade undisturbed communities
• Why are invasives successful?
• no diseases, herbivores, parasites, predators
• better competitors than native species

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• 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

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• Net result of invasive species
• homogenize ecological communities around the
  world
• drive native, endemic species extinct

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• Exploitation and overharvest
• Direct exploitation for food
• overfishing
• bycatch in fisheries killing non-target
  species (birds, marine mammals)
• bush meat harvest of wild animals for food
• can be sustainable, but often not
• threatens many large mammals, primates

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• Global trade in wildlife
• birds, orchids, cactus, primates
• captured for gardens, pets, zoos, etc.
• Many species driven extinct before
  hunting/harvest regulations were in place
• passenger pigeon, island tortoises, marine
  mammals

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• Exam
• Definitions, compare-contrast 5 points each (20
  points per page)
• 5 questions 12 points per question
• bonuses 3 points each
• dropped the question with the lowest score
• Average grade 86

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• Causes of species declines
• Habitat destruction and fragmentation
• Introduced species
• Exploitation and overharvesting
• Pollution
• Climate change

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• Pollution
• Most important for aquatic systems
• chemical pollutants
• acid precipitation
• Bioaccumulation process by which toxin
  concentrations increase in living tissues
• concentrations increase through the food chain

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• Climate change

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• Why do small populations go extinct?
• Demographic stochasticity chance events that
  occur at small populations size
• failure to breed or survive
• failure to find a mate
• skewed sex ratio

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Dusky Seaside Sparrow
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• Environmental effects unpredictable events that
  reduce survival or reproduction
• droughts, floods, fires, storms
• Genetic effects at small population size
• inbreeding
• genetic drift
• random mutations

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• Extinction vortex combination of genetic,
  environmental and demographic factors that drive
  a small population to extinction

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• Heath hen
• 1700 throughout the northeast coast
• 1907 50 left on Marthas Vineyard
• 1915 2000 birds
• 1916 fire
• 1917 goshawk invasion
• 1920s poultry disease
• 1927 13 birds, mostly males
• March 11, 1932 last known sighting

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• Minimum viable population smallest population
  has a specified probability of surviving for a
  certain time
• usually 95 chance of surviving for 100 years
• How big?
• at least 50 individuals to avoid demographic
  stochasticity
• at least 500 individuals to avoid genetic effects
• realistically gt 1000 but varies by species

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• Reasons for protecting biodiversity
• Intrinsic valuable for its own sake
• Instrumental beneficial to humans

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• Instrumental Reasons for Protecting Biodiversity
• Economic benefits
• food
• drugs
• cultivated crops
• ecotourism

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• Ecosystem services quantifiable services that
  an ecosystem provides to humans
• often very valuable economically
• Examples
• moderating climates
• mitigating floods and droughts
• eliminating waste and toxins
• pest control
• pollination

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• Pollinators
• Insects pollinate 2/3 of crop species
• 25 of foods consumed
• U.S. 20 to 40 billion in agriculture
• Evidence that many pollinators are declining
• bats
• honeybeeshummingbirds

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• Maintenance of ecosystem function
• How many species can you safely remove?
• How do you ensure maximum productivity in managed
  or natural ecosystems?

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• More diverse ecosystems are more stable

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• Diversity-productivity relationship
• How are plant species richness and primary
  productivity related?
• 3 possibilities

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• Why would productivity increase with richness?
• Greater odds of encountering a super-productive
  species
• Complementarity use of different resources by
  different species

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