Threats to Biodiversity chap 3

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Threats to Biodiversitychap 3

• Extinction is the most irreversible and tragic
  of all environmental calamities. With each plant
  and animal species that disappears, a precious
  part of creation is callously erased
• Michael Soule, 2004

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Threats to Biodiversity

• As our numbers climb, we expand agricultural
  conversion, import invasive species, hunt more
  species, degradate habitat, fragment and lose
  habitat, pollute water and air, impact climate
• In short, we are causing the 6th mass extinction,
  the only biological driven one

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Threats to Biodiversity

• Major factors impacting biodiversity

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Threats to Biodiversity

• Habitat Degradation
• Includes conversion from suitable to unsuitable,
  lowering quality, fragmentation that lower PVA
• Causes many industries (e.g. forestry,
  agriculture, development, fishing, mining,
  chemical)

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Threats to Biodiversity

• Overexploitation
• Hunting, collecting, fishing (and indirect
  by-catch), trade of animals (and parts)

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Threats to Biodiversity

• Invasive Species
• With our help, species have the ability to get
  virtually anywhere in the world
• Direct actions predation, parasitism, disease,
  competition or hybridization
• Indirect paths changing abundances, disruption
  of mutualisms, modifying habitat, reducing
  habitat quality)

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Threats to Biodiversity

• Anthropogenic Climate Change
• Climate has been a cause of previous mass
  extinctions
• Couple this with lower abundance, invasive
  species and other problems, a severe impact is
  likely from climate change
• Climate change will also trigger additional
  biological responses (e.g. malaria in temperate
  places)Fig 3.3

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Threats to Biodiversity

• Snowballing effect of the invasion of the alien
  root pathogen

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Threats to Biodiversity

• Snowballing effect of the invasion of the alien
  root pathogen
• Indirect effects

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Threats to Biodiversity

• Anthropogenic Pollution
• There are direct discharges of chemicals into the
  environment, there are also pollutants released
  into the atmosphere
• Toxic chemicals (e.g. mercury, lead) are found
  even in remote areas
• Also have the problem of bioaccumulation (or
  biomagnification)

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Threats to Biodiversity

• Toxic chemicals (PCBs and dioxins) accumulate in
  fatty tissues

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Anthropogenic Extinctions impact on communities
and ecosystems

• Loss of species, populations and/or habitat is
  dramatic and extreme
• Extinction as a process
• Can be local or global (also, ecological)

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Anthropogenic Extinctions impact on communities
and ecosystems

• Early extinctions probably caused by
  overexploitation
• Now, habitat degradation and/or invasive species
  major factors

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Anthropogenic Extinctions impact on communities
and ecosystems

• No. of genera (megamammal) extinct and cause
• 72 Aust
• 88 NAm

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Anthropogenic Extinctions impact on communities
and ecosystems

• Consider Polynesian colonization of Pacific
  Islands 1-3KYA
• Over 2000 species of birds (flightless rails) and
  8000 populations driven to extinction
• Story is not so simple
• Where invasive sp and habitat degradation
  combined, extinction followed

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Anthropogenic Extinctions impact on communities
and ecosystems
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Anthropogenic Extinctions impact on communities
and ecosystems

• Since 1500, gt129 sp extinct
• Habitat loss major cause
• Invasive sp contributed for many
• Overexploitation for 1/5

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Anthropogenic Extinctions indirect impacts

• Species dont exist in a vacuum and extinctions
  usually have a ripple effect
• Cascade effects such as secondary extinctions
  may occur
• E.g. plants with a single sp pollinator or seed
  dispersers
• E.g. sea otters and sea urchins

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Anthropogenic Extinctions indirect impacts

• Tambalacoque Dodo

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Anthropogenic Extinctions indirect impacts

• E.g. sea otters and sea urchins

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Anthropogenic Extinctions indirect impacts
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Anthropogenic Extinctions indirect impacts

• Another problem is the removal of top predators,
  which may cause the ecological release of
  mesopredators

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Anthropogenic Extinctions indirect impacts

• So there are many important species in a given
  community and some are more important than others
• Dominant sp common, but also have strong effects
  on other members
• Ecosystems engineers those that modify the
  ecosystem (e.g. beaver, elephant)
• Keystone sp sp that has more impact on community
  than numbers (biomass) would suggest (e.g. bat
  pollinator)

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Anthropogenic Extinctions indirect impacts
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Current Patterns of Global Endangerment

• Best data on global endangerment are collated in
  the IUCN Red List of Threatened Species
  (www.redlist.org)
• All species placed into one of 9 categories (3
  primary categories Critically Endangered,
  Endangered, Vulnerable)
• To date, only 2.5 of species evaluated (and 41
  considered endangered)

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Current Pattern of Global Endangerment
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Current Pattern of Global Endangerment
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Current Pattern of Global Endangerment

• What groups are in endangered?

Turtles at 42
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Current Pattern of Global Endangerment

• Globally threatened processes
• Some dramatic phenomenon may disappear (e.g.
  large-scale migrations)
• Read Essay 3.3

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Current Pattern of Global Endangerment

• Factors threatening biodiversity
• Factors are listed in the Red List
• Knowledge varies tremendously and by taxonomic
  group and habitat
• Most face multiple threats and threats can act
  synergistically

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Current Pattern of Global Endangerment

• Overexploitation is major cause for fish

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Current Pattern of Global Endangerment

• Where are sp most at risk worldwide?
• Not all biomes (and their inhabitants) are
  equally at risk
• Most tropical habitats and grasslands have large
  substantial numbers of threatened vertebrates

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Current Pattern of Global Endangerment
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Current Pattern of Global Endangermentthe US

• Geographically, there are very high numbers in
  SAm, SE Asia, sub-Saharan AF, Oceania, and NAm
  (where?)
• The US is second (Ecuador) for the number of
  species though to be at risk of extinction
  globally (IUCN)
• Many are plants (gt5000sp), freshwater species
  (e.g. mussels 70,crayfish, stoneflies)

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Current Pattern of Global Endangermentthe US

• Proportion of sp threatened in US

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Current Pattern of Global Endangermentthe US

• Examining threats to US sp

A correlative cause of many of these factors is
urbanization
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Current Pattern of Global Endangerment

• Threatened species in other countries
• Unfortunately, many countries lack solid data on
  what and how many sp are actually in trouble
• Some countries have a high proportion of the
  flora and fauna at risk
• E.g. Madagascar 80 of plants and 30 of
  vertebrates (case study 3.2)

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Current Pattern of Global Endangerment
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Current Pattern of Global Endangerment

• What types of sp are most vulnerable?
• Through studies, we have determined there are
  suites of characteristics that make some sp
  more vulnerable
• E.g. large range requirements, narrow habitat
  range, rarity, low reproductive rate, extreme
  specialization or co-evolutionary dependancies

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Current Pattern of Global Endangerment

• Vulnerability due to Specialization
• Many species (especially tropical) have narrow
  environmental ranges and highly specialized diets
  or habitats
• Perturbations can easily disturb them
• Specialization on other species can be precarious
  as well

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Current Pattern of Global Endangerment

• Top carnivores with low densities, large ranges,
  large body size, are often cited as being
  vulnerable to habitat degradation, as well as
  overexploitation
• For marine animals, body size itself does not
  appear to be a problem, but is associated with
  another

low reproductive rate
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Current Pattern of Global Endangerment

• Vulnerability of Rare species
• Why might a species be rare?
• Consider 3 characteristics geographic range,
  habitat breadth and abundance
• How might each influence vulnerability?
• How might they interact?

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Current Pattern of Global Endangerment
vent sp
bats
Island sp
raptors
seabirds
big cats
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Current Pattern of Global Endangerment

• Lets consider a case of extreme endemism
  Centinela Ridge in Ecuador
• During a RAP inventory, 90 endemic plant species
  were discovered
• Immediately following the inventory, entire ridge
  cleared for agriculture

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Current Pattern of Global Endangerment

• Island communities have relatively high rates of
  endemism, although communities maybe less rich
  than comparable mainland sites
• However, many island biotas are frequently
  endangered why?

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Current Pattern of Global Endangerment

• Case Study birds of Channel Islands
• 80 year comparison of pop(s)
• 40 of small pop(s) went extinct (lt10 bp)
• 10 of pop(s) with 10-100 breeding pairs
• 1 population of 100-1000 bp
• No pop(s) if gt1000 bp

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Current Pattern of Global Endangerment

• Bad luck species do not have intrinsically
  vulnerable traits, just bad luck
• For example, many freshwater fish near large
  cities are vulnerable, whatever their LHC
• 50 of variation in extinction risk for primates
  and carnivores is strictly due to anthropogenic
  distrubances

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Current Pattern of Global Endangerment

• Economic and Social Context
• Economic growth and rising affluence drive
  habitat conversion and overexploitation
• Unfortunately in the US, areas of high endemism
  and richness are areas of high human growth (e.g.
  s. CA, e-c TX, s FL)

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Current Pattern of Global Endangerment

• At the other end of the economic spectrum,
  billions live in poverty
• 1B lt 1/day
• 2.7B lt 2/day
• As a result, unsustainable levels of burning,
  small-scale agriculture, grazing and bushmeat
  hunting occur wherever these practices help
  people survive

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Current Pattern of Global Endangerment

• Responses to the Biodiversity Crisis
• Conservationists and developers agree where
  solutions need to come from
• 1) scientific analysis and promotion of the
  causes of biodiversity change
• 2) technological improvements
• 3) legal and institutional instruments
• 4) economic incentives and plans
• 5) social interventions

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Current Pattern of Global Endangerment

• Solutions will include
• Establishing protected areas
• Targeted interventions at the genetic, species,
  and ecosystems levels
• Restoration of damaged ecosystems
• Recovery of endangered species
• Creation of sustainable forms of development

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Current Pattern of Global Endangerment

• Single-species approaches will not be enough to
  conserve biodiversitylarger spatial scales are
  going to be needed
• However, many conservation actions are achieved
  at smaller scales (i.e. local)
• Need to prioritize and plan at larger scales
  (consisting of local partners)

Conservationists are generally asking where
questions to set geographical priorities and
how questions about developing and implementing
strategies to conserve conservation targets at
priority places Redford 2003
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Laws and International Agreements

• One major tool for conservationists are US laws
  and international agreements
• Please Review Case Study 3.3!!

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Driving Factors and Trends in Species Endangerment

• The first step is identifying a trend
• The second step is to determine what factors most
  influence trends
• Finally, establish a plan to remove or eliminate
  the identified threats
• As easy as they sound, none of these steps are as
  easy as they appear and the further along, the
  more external factors enter the process

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Driving Factors and Trends in Species Endangerment

• Besides developing a plan for a single species,
  important to track status trends to determine
  success
• The Red List Index tallies changes in status due
  to either a deterioration or improvement of all
  threatened species

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Driving Factors and Trends in Species Endangerment

• Overall, birds down 7
• Albatrosses and petrels down 25

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Driving Factors and Trends in Species Endangerment

• Unfortunately most species groups are too poorly
  known to adequately evaluate trends
• However there are a number of indicies attempting
  to bridge these gaps
• IBI (index of biotic integrity), LPI (living
  planet index pop change of 1100 terrestrial,
  marine, and freshwater vertebrate sp)

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Driving Factors and Trends in Species Endangerment

• Terrestrial sp (A) and broken down

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Driving Factors and Trends in Species Endangerment

• It is not enough to determine where changes are
  occurring (reactive), but rather perhaps we can
  use information to generate predictive models of
  what species or systems may be more vulnerable
  than others (proactive)

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Driving Factors and Trends in Species Endangerment

• Projected trends
• Dark most impact

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Driving Factors and Trends in Species Endangerment

• In the end, it is essential we better understand
  the factors that drive human behavior, which
  ultimately drive the causes of biodiversity loss

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Current Pattern of Global Endangerment