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.