Threats to Biodiversity

Resource consumption and human activities that support it form the foundational or root threat to biodiversity

• Current Major Threats to Biodiversity

• Habitat Related (Loss, Degradation, Fragmentation) • Pollution (Chemical, Light, and Noise) • Overexploitation • Invasive Species • Anthropogenic Climate Change • Disease (lesser threat to most taxa) • UV radiation (primarily threat to amphibians

• Synergistic Effects of Threats

Habitat Loss, Degradation, and Fragmentation

Overexploitation

Bioaccumulation

Synergistic Effects (1 + 1 = 3+ ?)

• Coral reefs – Climate change – Acidity – Fungi – Pollution

Secondary Species Loss and Extinctions

Cascade Effects One factor can create a trophic cascading domino-like effect within an ecosystem that leads to secondary losses of other species

The fungus that causes sudden oak death

Top-Down Regulation by Carnivores

Ecological Release

• What are the primary threats to biodiversity?

• How can these threats have effects greater than their individual contributions? – Provide an example – What is a trophic cascade, provide an

example, and describe how the secondary loss of species occurs?

In thinking about Extinction let’s recall the following info…

• Habitat Generalists – can exploit a variety of habitats within an area/range; can easily switch from available and/or preferred to less preferred habitats

Examples: White-tailed deer, elk, raccoon, bluegill, white oak

• Habitat Specialists – can exploit (usually very well) 1 or only a few habitats within an area/range; most habitats unsuitable and cannot be used Examples: Kirtland’s warbler, running buffalo clover, desert pupfish, red-cockaded woodpecker

Rare Species – population densities, range, and habitat specificity - Species with restricted geographical range - Species with only 1 or few populations - Species with small population sizes

• Declining Species • Occur at Sites of High Human Exploitation (poverty,

resource extraction, hunting/harvesting, urbanization, pollution)

What types of Species are Most Vulnerable To Extinction?

Note: Understanding the characteristics of extinction-prone species is important for anticipating how vulnerable species and biological communities are to certain activities. Even w/o detailed data we can make generalizations that help predict impacts and potential loss of these species and communities, but also helps to use and apply our valuable conservation and management dollars and efforts wisely.

Other Predictors of Extinction Vulnerability (Conceptualize why for each case)

• Large Space (Home Range) Requirements (wolverine, grizzly bear, tiger)

• Large-bodied Animals (bison, elephants, rhinos) • Ineffective Dispersers (plants with heavy, unpalatable seed pods,

those that are heavily predated • Seasonal Migrants (pronghorn, neotropical migrant songbirds)

• Species w/ Little Genetic Variability (cheetah)

• Species w/ Specialized Niche Requirements (desert pup fish, Kirtland’s warbler)

• Species found in relatively stable environments (tropical only species, pristine lakes)

• Species that form permanent or temporary aggregations (schooling fish, herding animals)

• “Naïve” species w/ no prior contact w/ humans (dodo bird)

• Species closely related to other extinct or near extinct/threatened species (rhinos, oryx, whales)

What factors are most threatening to biodiversity?

Note that while habitat loss and degradation remain the primary threat to most taxa, some organisms also face high threats from other factors.

Where are most taxa threatened with extinction?

Note: Black bars indicate # of threatened species

Why are some places in the U.S. such hot spots of endemism? What is it about these geographic

areas that make communities and the species they harbor relatively more vulnerable to extinction?

Conservation Databases

• Created in 1963 • System to classify threats to individual species • Classifies all species into 9 Status Categories • Not evaluated, Data Deficient, 3 Threatened Categories (Vulnerable, Endangered,

Critically Endangered), 2 Extinct Categories (Extinct in the Wild, Extinct), Near Threatened, and Least Concerned (see next slide for how the classification decision tree is constructed)

• General Evaluation Criteria by which Classification Decisions are Made:

– 1) population size and trends – 2) geographic range – 3) quantitative predictive models

IUCN (International Union for the Conservation of Nature and Natural Resources) Red List System:

IUCN Decision Tree

Note: By tracking the conservation status of species over time we can evaluate whether conservation measures are working.

If a species is considered threatened according to general criteria…then the “Red List Criteria” (Table 8.2 below) are used to further classify it into one of the 3 threatened categories.

“Blue List”

• http://www.bluelists.ethz.ch/ • Organized by few Swiss academics • Lists IUCN threatened (Red List) species that are

responding to conservation measures and suggests further measures to continue success.

Natureservee • http://www.natureserve.org/ • Covers U.S. and some of Canada and most of Latin America • Backed by The Nature Conservancy (non-profit) • Gives a conservation status ranks to “elements of interest” meaning

that in addition to individual species, also gives a conservation ranking to biological communities

• Ranking Criteria include: – # of remaining pops. – # of estimate individuals remaining (or extent/size of remnants

for communities) – # of protected sites that harbor the element – degree of threat – general vulnerability to known threats

• Ranks run from 1 thru 5, with 1 being critically imperiled to 5 being demonstrably secure

• Excellent biodiversity pubs at: • http://www.natureserve.org/publications/library.jsp

Knowledge of Threat (where, how, extent, why)

Identify priority actions

Develop strategies

Implement plan to slow, mediate, or reverse threat

Dealing with Biodiversity Threats: A schematic way to tackle them