Causes of Species Endangerment Topic 40

What is a Species? capable of interbreeding with one another in the wild (and produce viable offspring) but do not interbreed with other organisms about 2 million species have been named and described BUT …

Why Do We Need High Biodiversity? 4 main reasons: genetic reserves genetic engineering medicinal, agricultural, and industrial purposes aesthetic, ethical, and spiritual value

Genetic Reserves maintenance of a broad genetic base is critical for species’ long-term health and survival e.g. genetically uniform crops eventually lead to increased susceptibility to pests and disease we can avoid this problem by crossing crops with more genetically diverse ancestral relatives

Genetic Engineering the incorporation of genes from one organism into an entirely different species helps us obtain new vaccines, more productive farm animals, and longer lasting agricultural products

Medicines, Agriculture, and Industry the 20 best-selling prescription drugs in the U.S. are either natural products or manufactured drugs that were originally obtained from organisms ultimate sources of food, clothing, and shelter

Extinct Species extinction: the death of a species; occurs when the last individual member of a species dies irreversible and inevitable

Background vs. Mass Extinctions background extinction: continuous, low-level extinction of species mass extinction: periods in Earth’s history when numerous species disappeared during a relatively short period of geologic time episodes may have lasted millions of years caused by: major climate changes catastrophes

Present-Day Extinctions even though extinction is a natural process, it can be accelerated by human activity one of the main causes of recent extinctions is habitat destruction extinctions are currently occurring at 100-1,000x the natural rate of background extinction

Endangered and Threatened Species endangered species (legal definition): a species in imminent danger of extinction throughout all or a significant portion of its range threatened species: when extinction is less imminent but the population of a particular species is quite low (likely to become endangered in the foreseeable future)

Characteristics of Endangered Species species are vulnerable to extinction when they:

… Have a Localized Range some species have an extremely small (localized) range (conditions in which they are physically capable of living) extinction can occur if the habitat is altered

… Have a Large Territory Requirement extinction can occur if habitat is reduced e.g. California condor

… Live on an “Island” endemic species: species that are not found anywhere else in the world populations cannot be replaced by immigration evolved in isolation  why is this a problem? can also refer to species in any isolated habitat that is surrounded by an expanse of unsuitable territory habitat fragmentation: the breakup of large areas of habitat into small, isolated patches (“islands”)

… Have Low Reproductive Success some species have low reproductive success as a result of a small population size or low reproductive rates

… Have Specialized Breeding Areas if a species needs a specific area for breeding, that species is dependent on the habitat being there

… Have Specialized Feeding Habits if a species needs a type of food, the food source and the habitat need to be available

K-selected species tend to be susceptible Large, few in number, long-lived, and have few young

Declining Biodiversity in the U.S., declines are most noticeable in Hawaii, Florida, and California – why? worst declines: tropical rainforests (South and Central America, central Africa, and Southeast Asia) 7% of Earth’s land contains ~50% of Earth’s species

Biodiversity Loss in Rainforests 1% of rainforest is cleared/degraded every year  leads to species endangerment and/or extinction many species are endemic may affect species in other areas (e.g. migrating birds) clearing changes climate  fewer trees means less rain many organisms may not be able to tolerate new conditions

Biodiversity Loss in Rainforest cont. loss/degradation of rainforest may affect the evolutionary process adaptive radiation: the evolution of a large number of related species from an ancestral organism rainforest clearing reduces nature’s ability to replace its species countries where rainforest exists are usually the least equipped to protect them – why?

Biodiversity Hotspots relatively small areas of land high number of endemic species AND are at high risk from human activities about 25 identified  where? should we protect just these or focus on ALL biomes? Most are tropical/many are islands

Location of Biodiversity Hotspots

Human Causes of Species Endangerment causes include:

… Loss of Habitat * The single greatest cause of endangerment is LOSS OF HABITAT * construction, agriculture, logging, mining, or outdoor recreation

… Biotic Pollution the introduction of a foreign species into an ecosystem in which it did not evolve (aka exotic introduction) invasive species: the foreign species whose introduction causes economic or environmental harm often upset balance of area may compete with or prey upon natives typically caused by humans islands- particularly susceptible

… Environmental Pollution acid deposition, ozone depletion, and global warming affect ALL habitats

… Overexploitation deliberate efforts at eradication or control e.g. ranchers shooting wolves to protect livestock; prairie dogs being poisoned to prevent them from eating grass overhunting strictly controlled in many countries now e.g. U.S. Army killing bison to disrupt Native Americans/hunters killing them for their tongues

Overexploitation continued poaching = many animals killed for their furs, horns, skins, etc. black market commercial harvest: the collection of a live organism from nature organisms end up in zoos, aquaria, circuses, pet stores, etc. many organisms (especially birds) die in transit or from improper treatment endangered species sold to collectors

The Ugliness of Poaching

A Note on Frogs and Other Amphibians Bellwether species (sentinel species/indicator species): provide an early warning of environmental damage that has the potential to affect other species frogs/amphibians have been declining all over the world – why? agricultural chemicals, such as pesticides UV radiation caused by ozone thinning  affects egg survival infectious diseases global warming  reduced moisture levels

Frogs and Amphibians continued high percentages of several kinds of deformities extra legs and toes, eyes located on the shoulder or back, deformed jaws, bent spines, missing extremities and eyes can be caused by pesticides, parasites, high UV, or a combination of these factors