Chapter 23: Conservation Biology Flashcards
How has the military base Fort Bragg helped with conservation?
it has helped preserve the longleaf pine savanna and helped save the endangered red-cockaded woodpecker because it prevented large areas from being converted to farmland, forestry, or housing
Contributing Factors of Longleaf Pine Savanna decline
-fire suppression, human population growth, and clearing for plantations of other trees, such as loblolly pine
-oringinally covered 30 million hectares, now it covers only 3% of that
What does the red-cockaded woodpecker done to adapt to the savanna?
-they require mature, living pines for nesting
What has reduced the red-cockaded woodpecker population size?
loss of habitat, which makes them vulnerable to genetic drift, inbreeding, and extinction
How many red-cockaded woodpeckers were killed by Hurricane Hugo in 1989 in one population?
70%
How many species are listed threathened with extinction on the Red List of Threatened Species?
23,250 species
Conservation Biology
-is an integrative discipline that applies the principles of ecology to the protection of biodeiversity
-the scientific study of biodiversity, how human activites impact it, and how to maintain it and prevent its loss
What is the key to conservation biology?
integrative approaches that involve farmers, landowners, the US military, and business community
How do people rely on biodiversity?
We use hundreds of domesticated and wild species for food, fuel, fiber, medicines, building materials, spices, and decorative items
Ecosystem Services
natural processes that sustain life, such as water purification, soil formation, pollination of crops, climate regulation, and flood control
Alfred Russel Wallace
warned in 1869 that humanity was at risk of obscuring the record of past evolution by bringing about extinctions
When and why did the Ecologists’ Union branch off from the Ecological Society of America?
-1948
-they wanted to focus on preservation of species
What must conservation decisions be based on?
sound scientific analysis
Is biodiversity increasing or decreasing globally?
decreasing
Alwyn Gentry
-devoted his life to identifying, classifying, and mapping plant diversity in Central and South America
-eyewitness to plant species extinctions and identified endemic species
What is the extinction rate of mammals and birds from the fossil record?
one species every 200 years
What is the average species life span and how does that relate to the current extinction rate?
-Life Span: 1-10 million years
-Average Life Span with current extinction rate: 10 thousand years (1 extinction per year)
How much higher were extinction rates in the 20th century than the background rate?
100 to 1000 times higher
What do estimates of current extinction rates rely on?
-the species-area relationship
-changes in the threat status of species
-rates of population decline or range contraction of common species
Can extremely small populations serve the same ecological function as larger populations?
No
What did the colonization of the Pacific islands cause for the bird populations?
extinction of up to 8,000 species of birds
Why are small populations the focus of much reserach?
they are more vulnerable to genetic, demographic, and encironemtneal stochasticity
Extinction Vortex
a cyclic chain of events causes a small population to decline even furthur and become ever more vulnerable to processes that lead to extinction
What does a spatial approach track?
changes in a species range
What did a study of 173 declining mammal species worldwide show?
that these species had lost 68% of their range area
What does the extinction of a species do to the community?
-consequence for that species’ predators, prey, and mutualistic partners
-may bring about secondary extinctions and affects ecosystem function
The _____ the interactions of a species in the food web, the _____ the effect of its removal
stronger, greater
What type of effects do range expansions have and how do they occur?
-positive and negative effects that occur because movement and introduction of species has increased over the last century
What effects do non-natives have on biodiversity?
-negative effects
-reduce the range of native species who may already be declining
-hurst specialist for a certain habitat the most
What is the spread of introduced species and native generalists and the decline of native specialists leading to?
taxonomic homogenization
What is a positive effect non-natives can have?
provide habitat or food for rare species (rare cases)
What do species introductions increase?
regional biodiversity because the number of non-natives introduced to a region typically exceeds the number of native species that become extinct
What habitats are particuarly vulnerable to invasions and extinctions?
islands
What did the survey of American Samoa find (Cowie 2001)?
-found 19 of 42 native species of land snails and 12 non-native species
-high abundance of non-natives with natives declining
-Non-native predators contributed to the decline of natives
-homogenization of land snails is widespread on Pacific Islands
Rahel (2000)
-examined the change in number of species shared between all possible pairs of the lower 48 states
-On average, pairs of states shared 15 or more species than they did at the time of European Colonization
What are primary threats to biodiversity?
habitat loss, invasive species, overexplotation, pollution, disease, and climate change
What contributed to the extinction of the Pyrenean ibex?
overexplotation and competition with domesticated livestock
How many mammal species are currently threatened with extinction?
1,197 species
What are the primary threats to extinction of mammals?
loss of habitat, unregulated hunting, accidental mortality, pollution, and disease