Biology Chapter 17 Key Questions

What is natural selection?

process in nature by which organisms better adapted to their environment tend to survive and reproduce more than those less adapted to their environment.

How do vestigial structures provide evidence for evolution?

provide evidence for evolution because they suggest that an organism changed from using the structure to not using the structure, or using it for a different purpose.

What three kinds of variations among organisms did Darwin observe during his voyage?

1. species vary globally 2. species vary locally 3. species vary over time

How does Hardy-Weinberg apply to evolution?

Hardy-Weinberg equilibrium principle describes the unchanging frequency of alleles and genotypes in a stable, idealized population. ... In the absence of these evolutionaryforces, the population would reach an equilibrium in one generation and maintain that equilibrium over successive generations.

sources of genetic variation

Mutations, Genetic Recombination in sexual reproduction, and lateral gene transfer.

what hypothesis have the grants been testing?

Natural selection shaped the beaks of different bird populations

What is the difference between a single-gene trait and a polygenic trait?

Single gene traits: controlled by a single gene that has two alleles (ex: widow's peak) - only two phenotypes are possible - widow's peak or no widow's peak.Polygenic traits: controlled by two or more genes. Has 2 or more alleles. One polygenic trait can have many possible genotypes and phenotypes!

In evolution, why have small changes in Hox genes had a significant impact?

Small changes in these genes during the development can create significant differences in the appearance of such body parts when they become adults.

what types of reproductive isolation may have been important in Galapagos finch speciation? Explain.

Speciation in Galapagos finches could have occured by the finding of a new population, geographic isolation, changes in the new population's gene pool, behavioral isolation, and ecological competition.

What is geographic isolation?

Whenever a physical barrier divides a population

What is sympatric speciation?

a species evolves into a new species without a physical barrier

What are the patterns of evolution?

coevolution, convergent evolution, divergent evolution

What is involved in the process of artificial selection?

human intervention in animal or plant reproduction or survival to allow any individuals with desired traits to produce, also known as selective breeding

What are Darwin's Ideas of Evolution?

individuals of a species are not identical; traits are passed from generation to generation; more offspring are born than can survive; and only the survivors of the competition for resources will reproduce.

how is biogeography useful for identifying evolutionary relationships?

is useful because it shows us the geographical distribution of organisms. In other words, it tells us where the plants and animals live, including their ancestors.

How is inherited variation used in artificial selection?

nature provides the variations, and humans select those they find useful.

HWP five conditions that disturb genetic recombination:

non-random mating, small population size, immigration. and emmigration, mutations, and natural selection

how did Malthus explain population growth?

population grows exponentially, thus out-growing a society's resources. forces that work against population growth are war, famine, and disease

What is homology?

similarity due to common ancestry

What are the modes of isolation?

temporal, behavioral, geographical, and reproductive

What are acquired characteristics?

traits altered by an individual organism during its life

In genetic terms, what indicates that evolution is occurring in a population?

when the allele frequency of a population is changing.

Do homologous structures have the same ancestor?

yes. Structural homologies indicate a shared common ancestor

What three patterns of biodiversity did Darwin observe?

(1) Species vary globally, (2) species vary locally, and (3) species vary over time. Darwin noticed that different, yet ecologically similar, animal species inhabited separated, but ecologically similar, habitats around the globe.

What three conditions are necessary for natural selection to occur?

1. There should be a struggle for existence, which means that there are more individuals that are born than can survive. 2. There should be a presence of heritable variation. 3. There should be a different fitness rate among individuals to initiate the "survival of the fittest."

what have scientists learned from fossils that have been discovered since Darwin's time?

Darwin came across fossils that serve as clues to what the Earth was in the past. The fossils of extinct animals resemble some characteristics of the living species. This indicates that modern species have evolved from their extinct ancestors. These fossil form series trace how the evolution took place.

What did Charles Darwin contribute to science?

During his travels he made numerous observations and collected evidence that led him to propose a hypothesis about the way life changes over time, evolution

What did Hutton and Lyell conclude about Earth's history?

Earth is extremely old and that the processes that changed Earth in the past are the same processes that operate in the present.

How does the Hardy-Weinberg Principle work?

Evolution only occurs when a population is NOT in genetic equilibrium

How does evolution explain both the unity and the diversity of all living things?

He proposed that the relationship between individuals can be traced using an evolutionary tree to show how modern organisms are all linked to one another by their common ancestors. He also noted that the evolution in the species, which took place over the years, is responsible for the great diversity of life that we have on Earth.

what is the relationship between hox genes and embryological development?

Hox genes control the timing of development and growth of embryos. Organisms A and B have very similar Hox genes, and their embryos, in the earliest stages of development, are also very similar.

what role did Lamarck think acquired characteristics played in evolution?

Lamarck explained that due to the involvement of natural selection in the way animals use their organs or body parts, organisms have altered, acquired and lost particular traits in their entire lifetime. Those traits that are well-adapted to the environment are passed down to the next generation. As a result, evolution in the species occurs.

How did Lamarck propose that species evolve?

Lamarck suggested that organisms could change during their lifetimes by selectively using or not using various parts of their bodies. He also suggested that individuals could pass these acquired traits on to their offspring, enabling species to change over time.

how do mutation, genetic recombination during sexual reproduction, and lateral gene transfer produce genetic variation?

Lateral: It increases variation when a species picks up new genes from different species Mutations: create diversity within a population by introducing new alleles Genetic recombo: pieces of DNA are broken and recombined to produce new combinations of alleles. This recombination process creates genetic diversity at the level of genes that reflects differences in the DNA sequences of different organisms.

what does evolutionary theory suggest about the unity and diversity of life?

descents from common ancestors

how can crossing-over result in gene duplication?

during cross-over, there may be unequal swapping of DNA. one of the homologous chromosomes may receive extra DNA that carries part or all of a gene.

What is Darwin's theory of biological evolution?

evolution happens by natural selection.

What does Darwin's theory of evolution explain about the natural world?

explains how modern organisms evolved over long periods of time through descent from common ancestors. Darwin meant that different, yet ecologically similar, animal species inhabited separate, but ecologically similar, habitats around the globe.

What are the conditions necessary for natural selection?

reproduction, heredity, variation in fitness or organisms, variation in individual characters among members of the population

Under what conditions does natural selection occur?

reproduction, heredity, variation in fitness or organisms, variation in individual characters among members of the population.

how does a molecular clock allow scientists to study evolutionary history?

show the DNA mutation rate, scientists can estimate the amount of time that has passed since the two species shared a common ancestor. This method can show how these two organisms are closely related. The more mutations the longer it has been since the species shared a common ancestor.

What is the evolutionary theory?

the area that focuses on further development and refinement of the modern synthesis of evolution and genetics.