final Flashcards
Population?
a group of organisms of a single species occupying a particular area at the same time.
What causes the variation in a genotype?
Population genetics is the study of this diversity in terms of allele differences. It evaluates the diversity of a population by studying genotype and phenotype frequencies over time.
The Hardy-Weinberg Equilibrium states that:
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Allele frequencies in a population will remain constant assuming
- No Mutations
- No Gene Flow
- Random Mating
- No Genetic Drift
- No Selection
Hardy-Weinberg Equilibrium:
- Required conditions are rarely (if ever) met.
- Deviations from a Hardy-Weinberg equilibrium indicate that evolution has taken place.
- Analysis of allele changes in populations over time determines the extent to which evolution has occurred.
Homozygous dominant/recessive?
TT/tt
Heterozygous dominant?
Tt
Natural selection?
+Natural selection causes imperfect adaptations.
- it depends on evolutionary history
- Imperfections are common
Natural selection and adaptation:
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- Members of a population have inheritable variations.
- More individuals are produced in each generation than the environment can support.
- Organisms compete for available resources.
- Some individuals have adaptive characteristics.
- Favorable traits that result in increased survival and reproduction which causes organisms within a population to differ in their reproductive success.
Darwin used _____ principles to formulate his idea of natural selection.
Malthus’
Darwin’s natural selection hypothesis was based on:
Observation of tortoises and finches on the Galápagos Islands
Geneflow?
(Gene migration) Movement of alleles between populations when:
- Gametes or seeds (in plants) are carried into another population
- Breeding individuals migrate into or out of population
Continual _______ reduces genetic divergence between populations
gene flow
Nonrandom Mating?
When individuals do not choose mates randomly
Assortative mating: (3)
- They select mates with the same phenotype with respect to a certain characteristic.
- They reject mates with different phenotype
- It can play an important role in the evolution of a population
Allele frequency?
It is the proportion of each allele within a populations genepool.
the gene pool of a population can be described in terms of ________ and ________.
Genotype frequencies and Allele frequencies
________ in a population will remain constant assuming- no mutations, no gene flow, random mating, no genetic drift, and no selection
Allele frequencies
Genetic drift?
+Changes in the allele frequencies of a population due to change rather than selection by the environment
- Does not necessarily lead to adaptation to the environment
- Occurs by disproportionate random sampling from population
- Stronger effect in small populations
- Likely to occur: after a bottleneck, when severe inbreeding occurs, or when founders start a new population
What are the three types of natural selection?
Directional, Stabilizing, and disruptive.
Directional selection?(4)
- An extreme phenotype is favored.
- The curve shifts in one direction.
- Bacteria become resistant to antibiotics.
- Body size increases in horse evolution
Stabilizing selection?(2)
-An intermediate phenotype is the most adaptive for the given environmental conditions. -The peak of the curve increases and tails decrease.
Ex. Human babies with low or high birth weight are less likely to survive
Disruptive selection?(
- Two or more extreme phenotypes are favored over the intermediate phenotype.
-The curve has two peaks
Ex. British land snails vary because a wide geographic range causes selection to vary
Stabilizing selection?
An intermediate phenotype is the most adaptive for the given environmental conditions. -The peak of the curve increases and tails decrease.
Ex. Human babies with low or high birth weight are less likely to survive
Tell what most birds male dominant appearance look like?
Flamboyant and colorful
Geographical isolation
occurs when no migration occurs, the genetic makeup is too large, the genepool becomes more different
The bottleneck effect
a random event presents a majority of individuals from entering the next generation
-The next generation is composed of alleles that just happened to make it
Adaptation?
Change that helps a species become more suited to its environment.
-Product of natural selection
Define fossils?
the remains and traces of past life or any other direct evidence of past life such as traits, footprints, or preserved droppings. They record the history of life from the past
Tell how animal fossils form?
- Animal dies and is burried by sediment. 2. Extreme pressure turns sediment into stone. 3. Skeleton dissolves and leaves hole/mold. 4. Minerals crystalize in hole and a cast is formed. 5. Millions of years later, the fossil is exposed on the earth’s surface.
Know about the galapagos islands
+Tortoises
-Darwin observed that tortoise neck length varied from island to island.
-He proposed that speciation on islands correlated with a difference in vegetation.
+Finches
-Darwin observed many different species of finches on various islands.
-Significant variety in beaks
-He speculated that they could have descended from a mainland finch species.
Know about what darwin discovered about the finches on the galapagos island-
Flinches
-observed many different species of them on various islands. -Significant variety beaks. -He speculated that they would have descended from a mainland finch species
Know what Darwin said about evolution and when and how it occurred?
+Individual organisms in nature differ from one another. Some of this variation is inherited. +Organisms in nature produce more offspring than can survive and many of those that survived do not reproduce.
+Because more organisms are produced than can survive, members of each species must compete for resources.
+Because each organisms is unique each has different advantages and disadvantages in the struggle for existence. +Believed the view of nature was determined by deep-seated beliefs held to be intractable truths rather than experimentation and observation.
Know about homologous structures?
Anatomically similar because they are inherited from a common ancestor. May be functionally similar or not. All contain the same sets of organized bones in similar ways
vestigial structures
Fully developed anatomical structures in one group of organisms. -Reduced or obsolete function in similar groups
evolution?
is the unifying principle of biology- explains the unity and diversity of life
Microevolution
pertains to evolutionary changes within populations
Artificial selection
a breeder chooses which traits to perpetuate and selects the plants and animals that will reproduce
How old is the earth
4.6 Billion Years old
What call the earth formation of pangea to break apart?
Continental drift
What does half life mean? Radioisotope?
Half life is the length of time required for half the atoms to change into another stable element. Unaffected by temperature, light, pressure,. All radioactive isotopes have a dependable half life. It occurs at a constant rate. Many isotopes are used in absolute dating and their combined half lives make them useful.
The age of fossils?
The age of fossils in strata has helped them come up with a geological timescale
Charles Lyell?
Earth is a subject to slow but continuous cycles of erosion and uplift
He proposed uniformitarianism, which states that rates and processes of change are constant
Stanley Miller and Harold Urey (1953)
Conducted an experiment to test the Oparin/Haldane hypothesis. -Showed that gases can react with one another to produce small organic molecules.
Fossils
are the remains and traces of past life
What comes after dna?
RNA
First cells were either anaerobic or aerobic?
Anaerobic
Ecology?
the branch of biology that deals with the relations of organisms to one another and to their physical surroundings.
Anaerobic gives rise to
prokaryotic oxygen
Aerobic Prokaryotes give rise to the
Mitochondria
strata of the same age tend to contain the similar fossil _______ (____ ____) that can be used for relative dating?
assemblages (index fossils)
