Chapter 18

Topics: Extinction, Endangered species, Biodiversity Pages: 6 (1657 words) Published: December 9, 2012
Chapter 18 Summary/Notes
Conservation of Biodiversity

Modern Conservation Legacies
* The world is in a sixth mass extinction (the biodiversity is declining at a rapid rate) * Causes are mostly by human activities
* Habitat destruction
* Overharvesting plant and animal populations
* Results in growing interest in conserving biodiversity by setting aside areas that are protected from any human activities * Establishing national parks, national monuments, national forests, wilderness areas * Does not protect against gas and oil drilling

We are in the midst of a sixth mass extinction
* The biodiversity of the world provides instrumental and intrinsic values to humans * Instrumental: provisions (food, medicine, building materials), regulating services (the ability of plants to remove human-added carbon dioxide from the atmosphere), support services (pollination of crops) * Intrinsic: no direct benefit but the belief that individuals, species, and ecosystems are inherently valuable in themselves and we have an obligation to preserve them * The world has experienced 5 major extinctions during the past 500 million years and we are currently in another * Extinction – when the last member of a species dies

* The world is experiencing approx. 50,000 species extinctions per year * 0.5% of the world’s species each year
* This extinction is unique for:
* It is happening over a relatively short period of time * The rate of decline has been 100x to 1,000x faster during the past 50 years * Is the first to occur since humans have been present on earth * Has a human cause

Global Declines in the Genetic Diversity of Wild Organisms
* Populations with low genetic diversity are not well suited to surviving environmental change * Are also prone to in breeding depression
* Inbreeding depression – when individuals with similar genotypes-typically relatives-breed with each other and produce offspring that have an impaired ability to survive and reproduce * Occurs when each parent carries one copy of a harmful mutation in its genome * When parents breed, some of their offspring receive two copies of the harmful mutation, resulting in having poor chances of survival and later reproduction * High genetic diversity ensures that a wider range of genotypes are present, which reduces the probability that an offspring will receive a harmful mutation * Also improves the probability of surviving a future change in environment * Occurs because it produces a wide range of phenotypes that survive and reproduce under different environmental conditions * Some declines in genetic diversity have natural causes

* i.e. a population bottleneck
* Others are caused by humans
* Efforts to eradicate harmful species become intense when a human populations grow * Habitats disappear as humans settle on the land and increase agriculture * Hunting and habitat destruction

* Inbreeding causes a number of harmful effects
* Like hear defects and abnormal sperm
* Lack of genetic diversity can cause a population to decline even further Global Declines in the Genetic Diversity of Crops and Livestock * There are major concerns about declining genetic variation in the species of crops and livestock that humans depend on * The UN notes that majority of livestock species comes from seven species of mammals * Donkeys, buffalo, cattle, goats, horses, pigs, sheep * And four species of birds

* Chickens, ducks, geese, turkeys
* In other parts of the world, these species have been bred for a variety of characteristics like adaptations to survive local climates * The wide variety of characteristics could be used for adapting to changing environmental conditions in the future or resisting new diseases * Livestock producers have concentrated their efforts...
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