ENS-112 Environmental Science Chapter 8 PDF

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Chapter 8 notes from Dr. Adrienne George's lectures for ENS-112 Environmental Science at The University of Tampa...

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Environmental Science 112 FALL SEMESTER 2018 INSTRUCTOR: DR. Adrienne George [email protected]

Chapter 8: Biodiversity and Conservation Biology Life’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

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○ 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 biodiverse

Many 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 examination

Benefits of Biodiversity ● Biodiverse regions provide many benefits, such as potential new or unused food sources

Organisms provide drugs and medicines ● About half of today's pharmaceuticals are derived from chemical compounds in wild plants

Biodiversity provides ecosystem services ● Biodiversity provides many free benefits, including ○ Food, fuel fiber shelter ○ Air and Water purification ○ Waste decomposition ○ Climate stability ○ Pollination of plants 2

○ Controlling pests and diseases ○ Maintaining genetic diversity for crop varieties and livestock ○ Cultural and aesthetic benefits

Biodiversity 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 economy

People 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 people

Do 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 species

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Biodiversity 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 chain

Many 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 I Ndex 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 mammal

Earth has experienced five mass extinctions events

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● 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 extinction

We 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 gradual, piecemeal degradation called habitat fragmentation ○ This makes habitats smaller, and prevents movement of organisms between habitats ○ The proposed Serengeti highway would have caused habitat fragmentation ● Habitat loss has affected every biome, with wetlands being especially threatened ● Habitat loss is the primary source of population decline in more than 80% of threatened birds and mammals ● Pollution harms organisms in many ways

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○ Air pollution degrades forests and affects the atmosphere and climate ○ Noise and light pollution affect the behavior and habitat use of animals ○ Water pollution directly harms fish and amphibians ○ Agricultural runoff affects the food webs of aquatic ecosystems ○ Persistent pollutants like heavy metals directly poison people and wildlife ○ Plastic in the ocean can strangle. Drown, or choke marine animals ● Our growth in population and consumption is leading us to remove species at faster rates than they can reproduce ○ Valuable trees, like teak and mahogany, are disappearing quickly ○ Gorillas and other primates killed for “bush meat” could face extinction ○ Many ocean fish are overharvested ● Poaching is the illegal killing of wildlife for meat ot body parts ● Invasive species, non-native species introduced to new environments, can proliferate and displace natural species ● Species native to islands are particularly vulnerable, as the have been isolated from new parasites, predators, and competitors ● Climate change, warming temperatures causing some animals to shift their ranges to be closer to the poles or higher in altitude ○ Organisms already living in these places, such as the polar bear, have nowhere left to go and are especially vulnerable

A mix of causes threatens many species ● For many species, multiple factors are contributing to decline ○ Monarch butterflies are in decline because of the loss of milkweeds due to herbicide use and habitat loss ● The worldwide collapse of amphibians is due to a “perfect storm” of factors, including habitat destruction, chemical pollution, invasive species, climate change, and disease

Conservation Biology: The Search for Solutions

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● Conservation biology is a study that seeks to understand the loss, protection, and restoration of biological diversity

Conservation biology responds to biodiversity loss ● Conservation geneticists determine the minimum viable population size: how small a population can become and how much genetic variation it can lose before encountering inbreeding depressions ○ By determining this size, they can….

Endangered species are a focus of conservation efforts ● The Endangered Species Act (ESA) of 1973 offers protection to species that fall within two categories ○ Endangered: ○ Threatened ● The ESA forbids the U.S. Government and citizens from taking actions that destroy individuals within identified species ● Early successes of the ESA include the recovery of the Bald EAgle, peregrine falcon, brown pelican, and other birds following the ban of DDT in 1973 ● A common perception is that it imperils livelihoods ● Despite this perception, the ESA does not always stop development projects - it can promote cooperation with landowners ○ Habitat conservation plans allows the landowner to harm some individuals of a species if the overall habitat is improved ○ Harbor agreement - promise that the government will not pursue additional action if the landowner pursues actions that assist in the species’ recovery ● The 1973 Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITIES) bans the international transport of the body parts of rare species ● The convention on Biological Diversity is a treaty that provides funding and incentives for conservation in developing countries

Captive Breeding, reintroduction, and cloning are being pursued

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● Zoos and botanical gardens have become centers for captive breeding, where endangered individuals such as black rhinos are bred and raised and then released back into the wild ● The California condor was a victim of hunting and lead shot poisoning, dwindling to only 22 individuals by 1982 ○ Captive breeding programs have released 268 Condors into the wild, with 167 still in captivity ○ Lead shot poisoning is still a problem ● A new idea is to take DNA from an endangered species, insert it into an egg from a related species (that lacks a nucleus) and implants it into a female ● The protection of Umbrella species helps protect many others ○ The Wildebeest of the Serengeti, for example, have a huge range. Protecting them results in the protection of many other species as well ● Environmental Organizations use large charismatic vertebrates as flagship species to promote conservation ○ The symbol of the World Wildlife Fund, for example, is a panda

Several Strategies help to protect habitats, communities, and ecosystems ● Biodiversity Hotspots are regions that support…

Community-based conservation is growing ● In the past, conservationists from developed countries would work to preserve ● ecosystems while neglecting the needs of the local people ● Today, community-based conservation actively engages local people ● This approach will be vital to preserve biodiversity in the face of growing future human populations

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