APES Chapter 5
evolution by artificial selection
selective breeding of domesticated plants and animals to produce offspring with desired genetic traits
evolution
A change in the genetic composition of a species over time
recombination
A combining of genes or characters different from what they were in the parents
species evenness
Abundance of individuals within each species contained in a community
genetically modified organisms
An organism whose genetic material has been altered through some genetic engineering technology or technique
phenotype
An organism's appearance or other detectable characteristics
microevolution
Change in gene frequencies between populations of a species over time
mass extinction
Event in which many types of living things become extinct at the same time
How does geographic isolation lead to reproductive isolation?
If individuals cannot move between the populations, then over time, the two geographically isolated populations will continue to become more and more genetically distinct. Eventually, the two populations will be separated not only by geographic isolation, but also by reproductive isolation: they will become so different that even if the physical barrier were removed, they could no longer interbreed and produce viable offspring.
What is evolution, and what are the three main ways in which it occurs?
Evolution is the change in the genetic composition of a population over time. It occurs by artificial selection, by natural selection, and by random processes.
How does evolution lead to biodiversity?
Evolution produces more changes within a species, therefore increasing diversity.
macroevolution
Evolutionary change above the species level, including the appearance of major evolutionary developments, such as flight
How are human activities affecting extinction rates, and why is their impact a particular concern?
Human causes include habitat destruction, overharvesting, introductions of invasive species, climate change, and emerging diseases. Because much of the current environmental change caused by human activities is both dramatic and sudden, environmental scientists contend that many species may not be able to move or adapt in time to avoid extinction.
Why is it challenging to determine the number of species on Earth?
It is challenging because some species are active only at night or live in inaccessible locations.
realized niche
Part of a species fundamental niche that it actually uses, limited by competition
fossils
Preserved remains of once-living organisms
genetic engineering
Process of making changes in the DNA code of living organisms
range of tolerance
Range of chemical and physical conditions that must be maintained for populations of a particular species to stay alive and grow, develop, and function normally
geographic isolation
Separation of populations as a result of geographic change or migration to geographically isolated places
reproductive isolation
Separation of species or populations so that they cannot interbreed and produce fertile offspring
How does environmental change determine species distribution? When does it lead to extinction?
Species vary in their ability to move physically across the landscape as the environment changes, so species distribution is affected. It leads to extinction when the environmental change is so severe that the organism cannot survive there any longer.
What factors influence a species' chances of adapting successfully to a change in its environment?
The factors are rate of environmental change, genetic variation, population size, and generation time.
allopatric speciation
The formation of a new species as a result of an ancestral population's becoming isolated by a geographic barrier
sympatric speciation
The formation of new species in populations that live in the same geographic area
fundamental niche
The full potential range of the physical, chemical, and biological factors a species can use if there is no competition from other species
genetic drift
The gradual changes in gene frequencies in a population due to random events
species richness
The number of different species in a community
What is the difference between species richness and species evenness? Why are they both important measures?
The number of species in a given area, such as a pond, the canopy of a tree, or a plot of grassland, is known as species richness. However, species evenness tells us whether a particular ecosystem is numerically dominated by one species or whether all of its species have similar abundances. They are both important measures because they reflect biodiversity.
How do fundamental niches and realized niches differ?
The suite of ideal conditions is termed the fundamental niche of the species. However, the addition of biotic factors more narrowly defines the parts of the fundamental niche that a species actually uses. The range of abiotic and biotic conditions under which a species actually lives is called its realized niche.
Ecosystem Diversity
The variety of ecosystems
Species diversity
The variety of species
Why are estimates of species diversity valuable to environmental scientists?
They are valuable because they can tell environmentalists how much diversity is in a given area and what animals dominate it.
Why is the pace of human-driven evolution faster than that of natural evolutionary processes?
Using genetic engineering techniques, scientists can now copy genes from a species with some desirable trait, such as rapid growth or disease resistance. However, natural evolution occurs very slowly.
How are artificial and natural selection similar? How are they different?
With artificial selection, organisms are produced that humans find pleasing. However, with natural selection, the environment determines which individuals survive and reproduce. They are similar because traits are assigned to organisms in both cases.
bottleneck effect
a reduction in the genetic diversity of a population caused by a reduction in its size
niche generalists
a species that can live under a wide range of abiotic or biotic conditions
niche specialists
a species that is specialized to live in a specific habitat or to feed on a small group of species
fitness
ability to survive and reproduce
genotype
complete set of genes in an individual
mutation
occasional mistake in the copying process produces these random changes
genes
physical locations on chromosomes within each cell of an organism
founder effect
random change in the gene pool that occurs in a small, isolated colony of a population
distribution
the areas in the world where a species actually lives
phylogenies
the branching patterns of evolutionary relationships
evolution by natural selection
the principle that, among the range of inherited trait variations, those that lead to increased reproduction and survival will most likely be passed on to succeeding generations
adaptations
traits that improve an individual's ability to survive and reproduce
genetic diversity
variety of genes