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Conservation Biology and Global Change (Human activities threaten Earth’s…
Conservation Biology and Global Change
Human activities threaten Earth’s biodiversity
Genetic diversity comprises not only the individual genetic variation within a population but also genetic variation between populations associated with adaptations to local conditions.
The U.S. Endangered Species Act (ESA) defines an endangered species as one that is “in danger of extinction throughout all or a significant portion of its range,” and a threatened species as one likely to become endangered in the foreseeable future.
Ecosystem services encompass all the processes through which natural ecosystems and the species they contain help sustain human life on Earth.
Introduced species, also called nonnative or exotic species, are those that humans move, intentionally or accidentally, from native locations to new geographic regions.
The fourth threat to biodiversity, global change, includes alterations in climate, atmospheric chemistry, and broad ecological systems that reduce the capacity of Earth to sustain life.
Population conservation focuses on population size, genetic diversity, and critical habitat
A small population is vulnerable to inbreeding and genetic drift which draw the population down an extinction vortex toward smaller and smaller numbers until extinction is inevitable.
The minimum population size at which a species is able to sustain its numbers and survive is the minimum viable population size (MVP).
A meaningful estimate of the MVP requires the researcher to determine the effective population size (N e) based on the breeding potential of a population, incorporating information about the sex ratio of breeding individuals.
Landscape ecology and regional conservation help sustain biodiversity
One goal of landscape ecology is to understand past, present, and future patterns of landscape use and to make biodiversity conservation part of land-use planning.
Movement corridors, narrow strips or series of small clumps of habitat connecting otherwise isolated patches, can be deciding factors in conserving biodiversity.
Much of the focus has been on biodiversity hot spots, relatively small areas with numerous endemic species and a large number of threatened or endangered species.
A zoned reserve is a large region that includes areas undisturbed by humans surrounded by lands that are used for economic gain and have been changed by humans.
The key challenge of the zoned reserve approach is to develop a social and economic climate in the surrounding lands that is compatible with the long-term viability of the protected core area.
Earth is changing rapidly as a result of human actions
The nutrient level in an ecosystem may exceed the critical load, the amount of added nutrient that can be absorbed by plants without damaging ecosystem integrity.
Humans release an immense variety of toxic chemicals, including thousands of synthetic compounds previously unknown in nature.
Toxins may become more concentrated in successive trophic levels of a food web, a process called biological magnification.
If it were not for this greenhouse effect, the average air temperature at Earth’s surface would be a frigid –18°C (–2.4°F), and most life as we know it could not exist.
Ecologists are debating assisted migration, the translocation a species to a favorable habitat beyond its native range to protect the species from human-caused threats.
Sustainable development seeks to improve human lives while conserving biodiversity
Many nations, scientific societies, and other groups have embraced the concept of sustainable development, meeting the needs of people today without limiting the ability of future generations to meet their needs.
By reducing our orientation toward short-term gain, we can learn to value the natural processes that sustain us.
Modern lives reflect remnants of our ancestral attachment to nature and the diversity of life—the concept of biophilia.