Environmental Science Chapter 4 Objectives

What are three myths about evolution through natural selection?

"Survival of the fittest" means "survival of the strongest" - fittest to biologists means whoever has the most descendants Organisms develop certain traits because they need or want them Involves some grand plan in nature in which species become more perfectly adapted

What are two limits to evolution by natural selection?

Adaptive genetic traits must precede change in the environmental conditions Reproductive capacity

What is extinction?

An entire species ceases to exist

Distinguish between artificial selection and genetic engineering?

Artificial selection selects for traits already present in a species, whereas genetic engineering creates new traits. In artificial selection, scientists breed only individuals that have desirable traits. ... In genetic engineering, scientists use tools of DNA technology to directly manipulate a genome.

Distinguish between background extinction and mass extinction.

Background extinction: species disappear at a low rate Mass extinction: a significant rise in extinction rates above the background level.

What is the importance of biodiversity?

Biodiversity is a vital part to our natural capital that keeps us alive. It supplies us with food, wood, fibers, energy, and medicines—all of which represent hundreds of billions of dollars in the world economy each year. Biodiversity also plays a role in preserving the quality of the air and water and maintaining the fertility of soils. It helps us to dispose of wastes and to control populations of pests. In carrying out these free ecological services, which are also part of the earth's natural capital, biodiversity impacts and helps us each day.

Explain why birds are excellent indicator species.

Birds are excellent indicators because we know so much about their biology and life histories. They are sensitive to habitat change and are found almost everywhere in the world and in almost every habitat. They eat a variety of foods and as a ground have a broad range of niche requirements. Changes in bird populations can also provide a useful indication of broad environmental change.

Explain why we should protect the American alligator (Core Case Study) from being driven to extinction as a result of our activities.

Dig holes that provide water during dry spells Nesting mounds provide nesting and feeding sites for certain species Species also use old alligator nests to incubate their eggs Help keep areas of open water free of invading vegetation

What are the four major components of biodiversity (biological diversity)?

Ecosystem diversity - earth has a variety of grasslands, desserts, wetlands, etc Functional diversity - processes such as energy flow and matter cycling that help within the ecosystem as species interact with each other in food chains and food webs Genetic diversity - the variety of genes found in a population or species Species diversity -the number and variety of the species

Distinguish between specialist species and generalist species and give an example of each.

Generalist species: have broad niches Flies, mice, rats Specialist species: occupy narrow niches Tiger salamanders (breed only in fishless ponds)

Distinguish between geographic isolation and reproductive isolation and explain how they can lead to the formation of a new species.

Geographic isolation occurs when different groups of the same population of a species become physically isolated from one another for long periods. This leads to the formation of new species because they can lead to the development of quite different characteristics. Reproductive isolation: mutation and change by natural selection operate independently in the gene pools of geographically isolated populations. This leads to the formation of new species causing one species to become two because of such a different genetic makeup.

Describe how geologic processes and climate change can affect natural selection.

Geologic processes: Tectonic plates affect evolution and the location of life on earth Earthquakes volcanic eruptions Climate change: Ice ages followed by warming temperatures Collisions between the earth and asteroids

Why are amphibians vanishing and why should we protect them?

Habitat loss and fragmentation Prolonged drought Pollution Increases in UV radiation Parasites Viral and fungal diseases Climate change Overhunting Natural immigration of, or deliberate introduction of, nonnative predators and competitors amphibians are sensitive biological indicators of changes in environmental conditions such as habitat loss and degradation, air and water pollution, exposure to ultraviolet light, and climate change. adult amphibians play important ecological roles in biological communities. amphibians are a genetic storehouse of pharmaceutical products waiting to be discovered.

Distinguish among native, nonnative, indicator, keystone, and foundation species and give an example of each type.

Native species: are those species that normally live and thrive in a particular ecosystem Oak trees, maple trees Nonnative species: migrate into or are deliberately or accidentally introduced into an ecosystem Armadillos Indicator species: Species that provide early warnings of damage to a community or an ecosystem Frogs, coral, lichens (air quality bad) Keystone species: have a large effect on the types and abundances of other species in an ecosystem bees Foundation species: plays a major role in shaping communities by creating and enhancing their habitats in ways that benefit other species. algae

What is an endemic species and why is it vulnerable to extinction?

Species that are only found in one area Reasons they are vulnerable to extinction: Narrow geographical range Only one or few populations Small population size and little genetic variability Overexploitation by people

Distinguish between species richness and species evenness and give an example of each.

Species richness is simply the number of species in an area. Species evenness tells whether the ecosystem has a dominant species or has similar abundances of all species. Example: a rainforest may have a large number of different species (high species richness) but each species varies in size (low species evenness).

Explain why species-rich ecosystems tend to be productive and sustainable.

The more diverse an ecosystem is the more productive it will be along with more stable/sustainable. A place with different species provides more food options and better ways to respond to stressful environmental changes.

Describe the theory of island biogeography (species equilibrium model).

The number of different species (species richness) found on an island is determined by the interactions of two factors: the rate at which new species immigrate to the island and the rate at which species become extinct, or cease to exist, on the island. Darwin's finches were all the same when they arrived on the Galapagos islands. Now, they have evolved into 15 different species. These birds formed adaptations to fit their needs on the islands. The main way was their beaks. Darwin noticed that fruit-eating finches had parrot-like beaks and that finches that ate insects had narrow, prying beaks.

Why should we protect shark species from being driven to extinction as a result of our activities?

The ocean would be teeming with dead and dying fish if sharks were not at the top of the food chain to control that. Sharks could save human lives. Sharks almost never get cancer. If we can learn why this is, we could use it to fight cancer within our own species. Scientists are also studying their highly effective immune system, which allows wounds to heal without becoming infected.

Describe the role of the beaver as a foundation species.

They act as "ecological engineers," they build dams in streams to create ponds and other wetlands used by other species. They help shape and create the ecosystems around them. By eating plants and animals, and building dams, they make it possible for other species to thrive in that region as well. They are the ones who start the community by making dams. They provide more water for aquatic life and create more spaces to live for other organisms.

What is an ecological niche?

describes the role that a species plays in its ecosystem

What is differential reproduction?

enables individuals with the trait to leave more offspring than other members of the population leave.

What is an adaptation (adaptive trait)?

is any heritable trait that enables an individual organism to survive through natural selection and to reproduce more than other individuals under prevailing environmental conditions.

What is a fossil and why are fossils important in understanding biological evolution?

mineralized or petrified replicas of skeletons, bones, teeth, shells, leaves, and seeds, or impressions of such items found in rocks. IMPORTANCE: Fossils provide physical evidence of ancient organisms and reveal what their internal structures looked like Show that presently existing animals originated from now extinct

What is natural selection?

occurs when some individuals of a population have genetically based traits that enhance their ability to survive and produce offspring with the same traits.

What is a mutation and what role do mutations play in evolution by natural selection?

random changes in the structure or number of DNA molecules in a cell that can be inherited by offspring Sometimes a mutation can result in a new genetic trait that gives an individual and its offspring better chances for survival and reproduction under existing environmental conditions or when such conditions change.

Describe conditions on the earth that favor the development of life as we know it.

temp range: just right to support life orbit size: moderate temperatures liquid water: necessary for life rotation speed: the sun doesn't overheat the Earth size: gravity keeps the atmosphere

What is species diversity?

the number of different species it contains combined with the relative abundance of individuals within each of those species

What is biological evolution?

the process whereby earth's life changes over time through changes in the genes of populations

What is speciation?

two species arise from one

How did we become such a powerful species?

we have certain traits that allow us to adapt to and modify parts of the environment to increase our survival chances. strong opposable thumbs that allow us to grip and use tools better than the few other animals that have thumbs can do an ability to walk upright A complex brain With these three things we were able to develop weapons and devices and technologies that extend our limited senses and make up for some of our deficiencies.