biology Chapter 10-11 Flashcards
Define evolution.
Change in a species over time.Process of biological change by which descendents come to differ from their ancestors.
Who was the man behind evolution? What was the name of the ship he set sail on?
Charles Darwin-HMS Beagle
Define species.
A group of organisms so similar to one another that they can reproduce and have fertile offspring.
Who developed the present day classification system?
Carolus Linnaeus
What are fossils? How do they support evolution?
Traces of organisms that existed in the past. They are very different by layers that are formed over time in rock
Explain the differences among catastrophism,
gradualism
and uniformitarianism.
Catastrophism
- Georges Curvier-natural disasters such as floods and volcanic eruptions caused species to become extinct . New species then moved in from elsewhere accounting for the new species in the rock layers.
Gradualism
- James Hutton-Laying down of soil or Canyons, were not the result of large scale events, but were the result of slow changes over a long period of time. It has come to mean the gradual change of a species through evolution.
Uniformitarianism
- Charles Lyell-expanded Hutton’s theory of gradualism with his own observations that the geologic processes that shape earth’s landforms are uniform through time and have occurred at a constant rate and are ongoing. This greatly influenced Darwin.
Define variation
is the difference in the physical traits of an individual from those of other individuals in the group to which it belongs.
Define adaptation
-is a feature that allows an organism. To better survive in its environment. Adaptations can lead to genetic changes in population over time.
Define artificial selection
humans make use of the genetic variations in plants and animals by acting as the selective agent. Humans determine which trait is desirable.
Define heritability
is the ability of a trait to be passed down from one generation to the next.
Define natural selection
is a mechanism by which individuals that have inherited beneficial adaptations produce more offspring on average than do other individuals. In nature the environment is the selective agent.
Define population
all the individuals of a species that live in an area
What are the four main principles to the theory of natural selection? Describe each
Variation
-the heritable differences or variations that exist in every population. Result from differences in the genetic material of the organisms whether inherited or the result of a genetic mutation.
Overproduction
-having many offspring raises the chance that some will survive it also results in competition for resources.
Adaptation
-sometimes certain variations allow an individual to survive better than other individuals it competes against in the environment. More successful individuals are naturally selected.
Descent with modification
- Over time, natural selection will result in species with adaptations that are well suited for survival and reproduction in an environment. More individuals will have the trait in following generations as long as the environmental conditions continue to remain beneficial for the trait.
Define fitness
is the measure of the ability to survive and produce more offspring relative to other members of the population in a given environment.
Define biogeography
The study of the distribution of organisms around the world.
What are the four main pieces of evidence that support the theory of evolution?
Explain how each supports evolution.
Fossils
-Organisms in different layers of rock are different possibly lower layers were more primitive versions.
Geography
-Darwin noticed the similarity between organisms on an island and the main land, but also that over time they had developed different traits to adapt to the new environment.
Embryology
-the similar features of embryos I very different organisms suggest evolution from a common ancestor.
Anatomy
-comparing the body parts of different species showed similarity of structure in parts in different organisms. This was strong evidence for common descent.
Explain the difference between homologous and analogous structures. Give an example of each.
Homologous
-are features that are similar in structure but appear in different organisms and have different functions. Homologous structures are different in detail but similar in structure and relation to each other. Ex:forelimbs of tetrapod vertebrates. The forelimbs of humans, bats and moles have several bones that are similar to each other despite their different functions.
Analogous
-structures that perform a similar function, but are not similar in origin. Ex: Bat wings have bones but insect wings do not.
What are vestigial structures? Give an example. How do they support the theory of evolution?
Remnants of organs or structures that had a function in an early ancestor. They are evidence of common descent and gradual change or shrinkage in unnecessary organs. Ex: Ostrich wings are small as they do not need them to run away from predators..
Define gene pool
the combined alleles of all the individuals in a population.
Define allele frequency
is a measure of how common a certain allele is in the population.
What are the two main sources of genetic variation?
Mutation
-a random change in the DNA of a gene. This change can forma new allele.
Recombination
-New allele combinations form in offspring. Most combinations occur during Meiosis-the type of cell division need for sexual reproduction.. When gametes are made each parents alleles are arranged in new ways.
What is normal distribution?
When the frequency values are graphed the result is a bell shaped curve. It is highest in the middle and decreases to either side.
Explain the differences among directional selection, stabilizing selection and disruptive selection
Directional Selection
-a type of selection that favors phenotypes at one extreme of a traits range. An extreme phenotype that was once rare in a population becomes more common.
Stabilizing Selection
-the intermediate phenotype is favored and becomes more common in the population.
disruptive selection
-occurs when both extreme phenotypes are favored., while individuals with intermediate phenotypes are selected against by something in nature.
What is microevolution?
is the observable change in the allele frequencies of a population over time. Microevolution occurs on a small scale -within a single population.
