AP Biology: Evolution
Terms in this set (61)
Refers to the changes in one gene pool of a population
The development of an entirely new species
p² + 2pq + q² =1
Migration of individual's alleles into or out of the population (Ex. pollen from one valley can be carried by the wind across a mountain to another valley. Gene flow tends to INCREASE diversity).
Changes in genetic material and are the raw material for evolutionary change. A single point mutation can introduce a new allele into a population. INCREASE diversity.
Individuals choose their mates for a specific reason. The selection of a mate serves to eliminate the less- fit individuals.
The major mechanism of evolution in any population. Those individuals who are better adapted to the environment exhibit better reproductive success. They pass the genes to their offspring and so on.
The change in the gene pool due to chance. It is a fluctuation in frequency of alleles from one generation to another and is unpredictable. It tends to LIMIT diversity.
(Ex. Bottleneck and Founder effects)
Natural disasters such as fire, earthquake, and flood reduce the size of a population unselectively, resulting in a loss of genetic variation. (Ex. From 1820 to 1880, the northern Elephant seal was hunted to extinction. In 1884, the few remaining seals were placed under protection, and throughout the years the population has increased to 35,000; all are descendants from the original group that have little genetic variation)
The Founder Effect
When a small population breaks away from a larger one to colonize a new area, it is most likely not genetically representative of the original larger population. Rare alleles may be overrepresented. (Ex. All of the colonists descended from a small group of settlers who came to the U.S from Germany in the 1770's. Apparently one or more of the settlers carried the rare but dominant gene for polydactyly, having extra fingers and toes. Due to the extreme isolation and intermarriage of the close community, this population now has a high incidence of polydactyly.
The stock of different genes in an interbreeding population.
A diploid organism is heterozygous at a gene locus when its cells contain two different alleles of a gene. (Ex. Pp)
Homozygous is a genetic condition where an individual inherits the same alleles for a particular gene from both parents. (Ex. PP and pp) Dominant and Recessive
the proportion of a particular allele (variant of a gene) among all allele copies being considered. It can be formally defined as the percentage of all alleles at a given locus on a chromosome in a population gene pool represented by a particular allele. (Ex. p+q=1 where p represents the frequency of the dominant allele while q represents the frequency of the recessive allele)
a summation of all the organisms of the same group or species, which live in a particular geographical area, and have the capability of interbreeding.
An individuals collection of genes.
The organisms physical appearance.
refers to diversity in gene frequencies. Genetic variation can refer to differences between individuals or to differences between populations.
Aristotle spoke for the ancient world with his theory of Scala Natura. According to this theory, all life-forms can be arranged on a ladder of increasing complexity, each with its own issued support. The species are permanent and do not evolve. Humans are at the pinnacle of this ladder of increasing complexity.
Linnaeus specialized in taxonomy, the branch of biology concerned with naming and classifying the diverse forms of life. He believed that scientists should study life and that a classification system would reveal a divine plan. He is also known for inventing binomial nomenclature, where an animal has a special scientific name consisting of two parts; a genus and a species. (Ex. the scientific name for lions is Panthera Leo)
He studied FOSSILS and realized that each layer of earth is characterized by different fossils. He believed that a series of catastrophes was responsible for the changes in the organisms on earth and was a strong opponent of evolution. His study of fossils was VERY important to Darwin's theory.
One of the MOST influential geologists of his day, published his theory of GRADUALISM in 1795. He stated that the Earth had been molded, not by sudden violent events, but by slow, gradual change. He observed the effects of wind, water, and weather and that these were the same forces that formed the various geologic features on earth, such as mountain ranges and canyons. His theories were IMPORTANT because they were based on the idea that the Earth had a verryyyyy long history and that change is the normal course of events.
Was a leading geologist of Darwin's ERA. He stated that geological change results from slow, continuous actions. He believed that the Earth was much older than the 6,000 years thought by early theologians. His text, "Principles of Geology" was a great influence on Darwin.
Was a contemporary of Darwin who also developed a theory of evolution. He published his theory in 1809, the year Darwin was born. His theory relies on the ideas of Inheritance of acquired characteristics and use of disguise.
He stated that individual organisms change in response to the environment.
A naturalist and author, published an essay discussing the process of natural selection identical to Darwin's, which...had not yet been published.
a naturalist and author, who went to the Galapagos islands to study organisms. By the early 1840's, he had worked out his theory of natural selection but did NOT publish them. He later published "On the origin of the species" in 1859 when he was convinced. Darwin's theory challenged the traditional view of a young earth (6000 yrs old) inhabited by unchanging species.
Sometimes called purifying selection, eliminates the extremes and favors the more common intermediate forms. Many mutant forms are weeded out in this way. (Ex. In humans, stabilizing selection keeps the majority of birth weights in the 6-8 pound range. For babies much smaller and much larger, infant mortality is greater)
Increases the extreme types in a population at the expense of intermediate forms. What may result is called balanced polymorphism, one population divided into two distinct types. Over great lengths of time, disruptive selection may result in the formation of two new species.
Changing environmental conditions give rise to Directional Selection, where one phenotype replaces another in the gene pool. (Ex. the peppered moths issue in the industrial revolution, where the trees turned dark because of pollution, and the black moths then blended in while the white ones got eaten.......)
Selection based on variation in secondary sexual characteristics related to competing for and attracting mates. In the males, antlers, strength are the result of sexual selection.
Difference in APPEARANCE between males and females are known and sexual dimorphism.
Humans breed plants and animals by seeking individual with desired traits as breeding stock. (Ex. racehorses are bred for speed, and laying hens are bred to produce more and larger eggs)
Descent with modification
Descent with modification refers to the passing on of traits from parent organisms to their offspring. This passing on of traits is known as heredity, and the basic unit of heredity is the gene. Genes hold information about every conceivable aspect of an organism: its growth, development, behavior, appearance, physiology, reproduction. Genes are the blueprints for an organism and these blueprints are passed from parents to their offspring each generation.
Differential Reproductive Success
One individual or group having better success than another.......obviously:)
is a central idea in evolutionary and sexual selection theories. It can be defined either with respect to a genotype or to a phenotype in a given environment. In either case, it describes individual reproductive success and is equal to the average contribution to the gene pool of the next generation that is made by an average individual of the specified genotype or phenotype.
results from the propagation of advantageous mutations through positive selection. This is the modern synthesis of the process which Darwin and Wallace originally identified as the mechanism of evolution.
Populations tend to..
grow exponentially, overpopulate, and exceed their resources.
Overpopulation results in...
competition and a struggle for existence
In ANY population there is....
variation and an unequal ability of individuals to survive and reproduce.
Only the best-fit individuals....
survive and get to pass on their traits to offspring.
Directional selection can produce rapid shifts in allelic frequencies. For example, soon after the discovery of antibiotics, bacteria appeared that were resistant to these drugs. Scientists now know that the genes for anti-biotic resistance carried on plasmids, small DNA molecules, which can be transferred from one bacterial cell to another and which can spread the mutation for antibiotic resistance veryyy rapidly within the bacterial population.
when two or more clearly different phenotypes exist in the same population of a species—in other words, the occurrence of more than one form or morph. In order to be classified as such, morphs must occupy the same habitat at the same time and belong to a panmictic population (one with random mating)
when 2 different phenotypes can be found in different regions (remember the phet simulation with the bunny rabbits??)
When you mix 2 different sets of DNA, combining the genetic info from 2 different individuals...
when two or more characteristics are inherited, individual hereditary factors assort independently during gamete production, giving different traits an equal opportunity of occurring together.
Chromosomal crossover (or crossing over) is the exchange of genetic material between homologous chromosomes that results in recombinant chromosomes during sexual reproduction....so its basically when DNA from homologous pairs switches.
Sperm randomly picks egg
in genetics, the number of chromosomes occurring in the nucleus of a cell. In normal somatic (body) cells, the chromosomes exist in pairs. The condition is called diploidy. During meiosis the cell produces gametes, or germ cells, each containing half the normal or somatic number of chromosomes
when a cell has half the usual number of chromosomes. A normal eukaryote organism is composed of diploid cells, one set of chromosomes from each parent. However, after meiosis, the number of chromosomes in gametes is halved.
preserves multiple alleles in a population
breed from parents not closely related.
The fossil record reveals the existence of species that have become extinct or have evolved into other species. Radiometric dating and half life accurately measure the age of fossils. Prokaryotes were the first organisms to develop on earth, and they are the oldest fossils.
According to the theory of plate tectonics, continents and oceans rest on giant plates of the Earth's crust that float on top of the hot mantle. Convection currents in the mantle are responsible for the slow, continuous movement of the plates know as continental drift.
The study of different structures contributes to scientists' understanding of the evolution of anatomical structures and of evolutionary relationships. ex. the wing of a bat, human arm, and a whale fin, all have the same internal bone structure, although the function of each varies. these structures are known as homologous structures.
vestigial structures, such as the appendix, are evidence that structures have evolved. So basically a vestigial structure is something that we once had and did something, but don't to anything anymore. ex. tail
Structures that come from the same ancestor...have a common origin and reflect a common ancestry.
NOT from a recent common ancestor. like a bat wing and a fly's wing have the same function, but the similarity is superficial and reflects adaptation to a similar environment.
Occurs when a population becomes isolated (for ANY reason) from the rest of da species, becomes exposed to new selective pressures, and evolves into a new species.
When unrelated species occupy the same environment, they are subjected to similar selective pressures and show similar adaptations. The best example is a Whale. Which has almost the same appearance as a fish because the two evolved in the same environment. Originally, Whales' ancestry came from mammals, not fish.
Cellular/Molecular Evidence. All living things are fundamentally alike. At the cellular and molecular level living things are remarkably similar to each other. These fundamental similarities are most easily explained by evolutionary theory: life shares a common ancestor.
the branch of biology that deals with the normal functions of living organisms and their parts.
is the branch of biology that studies the development of gametes (sex cells), fertilization, and development of embryos and fetuses. Additionally, embryology is the study of congenital disorders that occur before birth.