Biology ch.13
The phrase Darwin used to describe his broad theory of evolution is ______
"Descent with modification"
The DNA difference between humans and chimps is____
1.8%
In human gamete production there is an average of _____ crossover events per chromosome pair.
2-3 These crossover events increase the genetic variation among gametes.
HMS Beagle
5 yr trip to map the coast of S. America, Darwin studied a wide variety of plants and amimals.
Fathers of evolutionary thought were ______
Alfred Russel and Charles Darwin
In The Origin of Species, Darwin reasoned in favor of two maim points:
All organisms inhabiting Earth today are derived from ancestral species that may have looked differently (descent with modification) The mechanism by which this was accomplished is natural selection.
Overproduction
All species produce more offspring in a generation than it would take to replace the parents. This leads to a struggle for existence among the offspring.
individual variation
All the individuals in a population have slightly different characteristics. Much of this variation is heritable.
The human immune system cannot effectively suppress the HIV virus on its own. What key feature of HIV makes it so hard to beat?
The HIV virus has an extremely high rate of mutation.
comparative anatomy
The comparison of body structures and how they vary among species. Such comparisons confirm that evolution is a remodeling process.
HIV has become an important source of mortality for humans. If AIDS persists as a major factor for humans for many generations in the future, natural selection theory predicts that _____.
any heritable traits that help humans survive and reproduce in the presence of AIDS should become more frequent over time
disruptive selection causes_____
both extreme phenotypes to be favored over the intermediate phenotype. This type of selection may occur when the habitat is varied.
genotype frequencies____
can be calculated from allele frequencies
stabilizing selection does not _______
change the mean of the population; only the extreme phenotypes become less common. Reducing variation.
Hardy-Weinberg equilibrium
condition that occurs when the frequency of alleles in a particular gene pool remain constant over time.
Fossils allow us to____
conduct detailed comparisons with animals living in other epochs.
Evolution is one of the best_____
demonstrated, most comprehensive, and longest lasting theories. It is a theory and adjustable, thus not a law.
Through ________ we are able to produce better applications of biology in medicine, pharmacology, agriculture, and other fields of research.
evolutionary patterns
molecular biology allows us to______
fine-tune the evolutionary relationships among species.
All the alleles of all the genes of a population make up a _____
gene pool
Modern travel along with migration reduces the probability of _____ having an effect on the evolution of humans.
genetic drift
The evolution of populations due to chance is _____
genetic drift
Four causes of Microevolution
genetic drift, gene flow, mutations, natural selection.
The founder effect is genetic drift______
in a new colony
The bottleneck effect____
is an example of genetic drift.
Homology
is similarity of structures resulting from common ancestry
Crossing over, resulting in an increase in genetic variation, occurs between_____
nonsister chromatids of homologous chromosomes
Tracking the genetic makeup_____
of populations over time allows us to determine whether a population is evolving and how fast it is changing.
Genetic drift
random change in allele frequencies(gene pool) that occurs in small populations.
Fossils are_____
remnants of organisms that lived in the past that have been turned to stone. (Organic material replaces with minerals.)
The fossil record is_____
the chronology of fossils in rock layers. Provides evidence that organisms appeared in a historical sequence.
The gene pool is___
the collective genome of the population. Includes all versions of alleles.
Darwinian fitness
the contribution that an individual makes to the gene pool of the next generation in comparison to the contributions from other individuals. For a human male to transfer all his genes into the next generation(requires passing on both his X and Y chromosome, meaning a son and a daughter)
After a bottleneck event has occurred
the genetic diversity of a population is decreased causing the population to be more vulnerable to extinction due to lack of genetic variation.
Directional selection
Favors phenotypes at one end of a range and is common in periods of environmental change.
Evidence for evolution comes in several distinctive forms:
Fossils. Biogeography. Comparative anatomy and embryology. Molecular biology. (Each contributes to the whole)
Which of the following events could NOT be caused by a population bottleneck?
Increased population size
_______ is a type of sexual selection in which individuals of one sex(usually males) compete directly for mates. This may involve ritualized displays or physical combat.
Intrasexual selection
Hardy-Weinberg formula
Is a mathematical representation of a gene pool. Adds up all of the genotypes in a population.
comparative embryology
Is the comparison of homologous structures that appear during the development of different organisms. All vertebrates together have a common ancestry bc of pharyngeal pouches and post anal tails (which are not present in adult mammals but are visible at certain points in embryonic development)
Analogy
Is the similarity of structures based on function.
Examples of natural selection scientists are studying right now include:
Pesticide resistance in insects. Development of antibiotic-resistant bacteria.
differential reproductive success
Phenomenon in which individuals with adaptive genetic traits produce more living offspring than do individuals without such traits.
The genes of individuals that are favored by differential reproductive success are_____will occur in greater frequency in the population than genes of individuals not favored _______
Selected for/ selected against
artificial selection
Selection by humans for breeding of useful traits from the natural variation among different organisms. Reproducing most wanted characteristics.
In sexual selection, individuals with certain inherited characteristics are more likely to obtain mates other than individuals. This often results in________, differences between the sexes in size, appearance, and behavior.
Sexual dimorphism
Genetic drift is a process based on _____.
the role of chance
A population is a_____
group of individuals of the same species living in the same area at the same time. This is the smallest unit that can evolve
Natural selection has_____
two conditions: overproduction and individual variation
Evolution has become the_____
unifying theme in biology
Darwin became convinced that the Earth was ...
very old, and had been shaped by slow processes, and continues to change everyday. Just as earth changed, or evolved, so could the organisms that lived upon it.
Using molecular clocks______
we can independently verify when a lineage split, and what the age of certain fossils should be.
sedimentary rock is______
where fossilization is most likely. Dust that floats then settles.
Natural selection answers the question______
why organisms live where they live.
Scientific evidence for evolutionary processes is not rare but_____
abundant
Evolution works_____
Blindly not perfectly(tail and pouch genes still in our DNA though we don't need them, gills turn to lower jaw in us.)
Microevolution
Change in allele frequencies in a population over generations.
________, who promoted the idea of an ancient earth
Charles Lyell
Fossils include
actual organisms(petrified trees), mineralized bones(dinosaurs), or impressions left by soft tissues(jellyfish).
Imagine that four people are infected with HIV from a common source (an infected blood sample). Initially, the patients' HIV populations are genetically identical. By the time they develop full-blown AIDS, how would the viral populations of the four patients compare?
Each patient's viral population would be unique, specifically adapted to deal with—and overcome—his or her unique immune system responses.
Natural selection can best be described as_____
a filtering process that fine-tunes the traits of populations by sorting among existing, randomly produced variations.
Gene flow
Movement of alleles into or out of a population due to the migration of individuals to or from the population.
Biogeography
Study of past and present distribution of organisms around the world. How certain species came to live where they do now, common ancestry in an evolutionary context is often the best.