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Chapter 5

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Mariah Lucernoni

on 19 April 2013

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Transcript of Chapter 5

Explain the concept of biodiversity and how it is measured. Evolution of Biodiversity Why is it challenging to determine the number of species on Earth? Check Point 1 What is evolution, and what are the three main ways in which it occurs? Check Point 2 How does geographic isolation lead to reproductive isolation?

Check Point 3 How do fundamental niches and realized niches differ?

Check Point 4 Species diversity: The variety of species within a given ecosystem. Vocab Geographic isolation: Physical separation of a group of individuals from others of the same species. Vocab Evolution by natural selection favors combinations of traits that perform well under particular environmental conditions. As a result, each species has a range of preferred abiotic conditions that constitute its fundamental niche. This fundamental niche is further restricted by biotic factors, including competition, predation, and disease, to form the species’ realized niche. Changes in environmental conditions therefore have the potential to change species’ distributions. Explain the concept of an ecological niche. Explain how environmental change affects speciation and extinction. Allopatric and sympatric speciation are two ways in which new species can evolve. Four factors that affect a species’ ability to adapt to environmental change are the rate of environmental change, the amount of genetic variation within the species, population size, and generation time. Evolution can occur through artificial selection, natural selection, or random processes. Artificial selection occurs when humans determine which individuals will mate and pass on their genes to the next generation to achieve a predetermined suite of traits. Natural selection does not favor a predetermined suite of traits, but simply favors those individuals that are best able to survive and reproduce. Random processes (mutation, genetic drift, bottleneck effects, and founder effects) do not favor a predetermined suite of traits, nor do they favor individuals with the highest fitness. Describe the ways in which evolution can occur. Biodiversity exists at three scales: ecosystem diversity, species diversity, and genetic diversity. Environmental scientists measure species diversity both by the number of species in a particular location (species richness) and by how evenly individuals are distributed among those species (species evenness). The greater the number of species, and the more even the distribution, the higher the diversity. Ecosystem diversity: The variety of ecosystems within a given region. Genetic diversity: The variety of genes within a given species. Species richness: The number of species in a given area. Species evenness: The relative proportion of different species in a given area. Phylogenies: The branching patterns of evolutionary relationships. What is the difference between species richness and species evenness? Why are they both important measures? Why are estimates of species diversity valuable to environmental scientists? Because some species are harder to find than others. So they know how many of each species live, who over powers other groups, etc. Species richness: The number of species in a given area. Species evenness: The relative proportion of different species in a given area. Evolution: A change in the genetic composition of a population over time. Microevolution: Evolution occurring below the species level. Macroevolution: Evolution that gives rise to new species, genera, families, classes, or phyla. Gene: A physical location on the chromosomes within each cell of an organism. Genotype: The complete set of genes in an individual. Mutation: A random change in the genetic code produced by a mistake in the copying process. Recombination: The genetic process by which one chromosome breaks of and attaches to another chromosome during reproductive cell division. Phenotype: A set of traits expressed by an individual. Evolution by artificial selection: A change in the genetic composition of a population over time as a result of humans selecting which individuals breed, typically with a preconceived set of traits in mind. Evolution by natural selection: A change in the genetic composition of a population over time as a result of the environment determining which individuals are most likely to survive and reproduce. Fitness: An individual’s ability to survive and reproduce. Adaptation: A trait that improves an individual’s fitness. Genetic drift: A change in the genetic composition of a population over time as a result of random mating. Bottleneck effect: A reduction in the genetic diversity of a population caused by a reduction in its size. Founder effect: A change in a population descended from a small number of colonizing individuals. How does evolution lead to biodiversity? How are artificial and natural selection similar? How are they different? Evolution: A change in the genetic composition of a population over time.
1)Natural
2)Artificial
3)Random The process of evolution by natural selection is similar to the process of evolution by artificial selection, with one key difference. In evolution by natural selection, the environment determines which individuals survive and reproduce Evolution can cause mutations creating a wide spread of species. Sympatric speciation: The evolution of one species into two, without geographic isolation. Genetically modified organism (GMO): An organism produced by copying genes from a species with a desirable trait and inserting them into another species. Why is the pace of human-driven evolution faster than that of natural evolutionary processes? What factors influence a species’ chances of adapting successfully to a change in its environment?
Two geographically isolated populations will continue to become more and more genetically distinct. Eventually,they will become so different that they can no longer interbreed and produce viable offspring, becoming distinct species. Rate of environmental change, genetic variation, population size, and generation time. Using genetic engineering techniques, scientists can copy genes from a species with some desirable trait, such as rapid growth or disease resistance. Scientists can insert these genes into other species of plants, animals, or microbes to produce genetically modified organisms. When those organisms reproduce, they pass on the inserted genes to their offspring. inserting genes into an organism is a much faster way to produce desired traits than traditional plant and animal breeding, which can only select from the naturally available variation in a population Range of tolerance: The limits to the abiotic conditions that a species can tolerate. Fundamental niche: The suite of ideal environmental conditions for a species. Realized niche: The range of abiotic and biotic conditions under which a species actually lives. Distribution: Areas of the world in which a species lives. Niche generalist: A species that can live under a wide range of abiotic or biotic conditions. Niche specialist: A species that is specialized to live in a specific habitat or to feed on a small group of species.

Fossil: The remains of an organism that has been preserved in rock. Mass extinction: A large extinction of species in a relatively short period of time. How are human activities affecting extinction rates, and why is their impact a particular concern? How does environmental change determine species distribution? When does it lead to extinction?
Fundamental niche: The suite of ideal environmental conditions for a species. Realized niche: The range of abiotic and biotic conditions under which a species actually lives. Habitat destruction, overharvesting, introductions of invasive species, climate change, and emerging diseases; many species may not be able to move or adapt in time to avoid extinction Areas of world where species live/ environment and adaptation to environment; if the species can't adapt
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