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UT ENS 112 - Chapter 8: Biodiversity and Conservation Biology

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Environmental Science 112FALL SEMESTER 2018INSTRUCTOR: DR. Adrienne [email protected] 8: Biodiversity and Conservation BiologyLife’s Biodiversity on Earth● Biodiversity is the variety of life across all levels of biological organization (genes through ecosystems)○ Ecosystem diversity → species diversity →genetic diversity● A species is a set of organisms that share unique characteristics and can breed and produce fertile offspring● Species diversity describes the number or variety of species found in a region○ Species richness describes the number of species○ Evenness or relative abundance describes how much the species differ from each other in numbers of individuals● Genetic Diversity includes differences in DNA composition among individuals○ Populations with little genetic diversity are more likely to suffer inbreeding depression and be vulnerable to environmental change, as they lack the variation needed to help adapt to new conditions● Ecosystem diversity refers to the number and variety of ecosystems within a larger area (forest, reef, ocean)Biodiversity is unevenly distributed● Some groups of organisms include more species than others○ Insects, for example, have the most species● Varies based on location● Species richness generally increases near equator due to 1○ Greater geographic areas○ More solar energy○ Stability of tropical climates○ Lack of disruptive glaciation events● Species diversity generally increases in areas with more diverse habitats● Structurally diverse habitats, like forests, are generally more biodiverseMany species aqwait discovery● So far, 1.8 million species of plants, animals, and microorganisms have been identified○ Estimates for the total number range from 3-100 million ● Our species knowledge is incomplete because most of the unknown species are small, such as bacteria, roundworms, fungi, and protists○ Other organisms may appear to be the same species but are found different upon examinationBenefits of Biodiversity● Biodiverse regions provide many benefits, such as potential new or unused food sourcesOrganisms provide drugs and medicines● About half of today's pharmaceuticals are derived from chemical compounds in wildplantsBiodiversity provides ecosystem services● Biodiversity provides many free benefits, including○ Food, fuel fiber shelter○ Air and Water purification○ Waste decomposition○ Climate stability○ Pollination of plants2○ Controlling pests and diseases○ Maintaining genetic diversity for crop varieties and livestock○ Cultural and aesthetic benefitsBiodiversity helps maintain ecosystem function● Biodiversity increases the resilience of an ecosystem - its ability to recover from a disturbance○ If a keystone species like a top predators is lost, consequences will cascade down the entire food chain○ If an ecosystem engineer is lost, the entire structure of an ecosystem can change■ The removal of elephants from some of Africa's savannas has caused scrubby vegetation to overgrow, turning them into scrub forests.Biodiversity boosts economies through tourism and recreation● Visitors to natural areas spend money at local businesses. Hire locals as guides, and support parks that employ residents○ For Tanzania, ecotourism provides a quarter of all foreign money entering the economyPeople value connections with nature● E.O. Norton (biologist) suggested that human beings share an instinctive love for nature and feel an emotional bond with other living things○ He called this biophilia● Other believe that a lack of outdoor experiences and direct contact with wild organisms contributes to the emotional stress, angst. and anxiety felt by many young peopleDo we have ethical obligations to other species?● Many feel that all living organisms have an inherent right to exist○ We need to use resources and consume other organisms to survive but we can make deliberate decisions to preserve other species3Biodiversity loss and extinction● The alteration of ecosystems creates “winners” and “losers” among the world’s animals and plants● Humans have a tendency to change ecosystems so that they are more similar to each other. More open in structure, and more polluted○ This favors generalists, which can adapt to the changing conditions, and harms specialists, which rely on mature, stable ecosystems● Organisms that benefit from human development also tend to be geographically widespread, smao and fast reproducing, and lower on the food chainMany populations are declining● As a population shrinks, it loses both genetic diversity and geographic range○ Both make the population vulnerable to further declines● The United NAtions Environment Programme (UNEP) developed the Living Planet INdex as a way to express how large the average population size of…● The Living Planet Index fell by 58% between …Extinction is irreversible● Extinction occurs when the last member of a species dies and the entire species ceases to exist● Extirpation is the loss of a species from one area, but not the entire world○ The Black Rhino has been extirpated from most of its historic range, but is not yet extinct● THe human impact is responsible for most extirpation and extinction today, but these processes do also occur naturally● The background extinction rate is the pace at which organisms independently go extinct○ Based on the fossil record, scientists estimate this rate at an average of 1 out of every 1-10 million mammalEarth has experienced five mass extinctions events4● Mass extinction events are events that eliminated at least half of the species on Earth○ Five have already occurred, and we are in the midst of the sixth mass extinctionWe ar5e setting the sixth mass extinction in motion● The current extinction rate is 100-1000 times greater than the background rate○ This includes many North American birds, such as the Ivory-billed woodpecker● The International Union for conservation of Nature (IUCN) maintains the Red List, which us a list of all species at high risk of extinction● The 2017 Red List reported that the following animals were threatened with extinction○ @1% of mammal species○ 13% of bird species○ 20% of reptile species○ 32% of amphibian species○ 14% of…Several major causes of biodiversity loss stand out● Habitat loss is the greatest threat to biodiversity today● Habitat loss most commonly occurs through

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