Biology Test 4 (Ch 14)

Darwin

Darwin

Observing the unique life forms on these islands, including the many types of finches, prompted ______ to wonder whether the environment causes populations to change.

vampire finches

______ _______ found on the Galápagos Islands have been observed feasting on the blood of large seabirds.

evolution

The many organisms that inhabit our planet are well matched to their environment as a result of _______

evolution

________ explains both the diversity of life and the similarities that exist among life forms.

HMS beagle

After his 5 years aboard the ____ _____, Darwin made a bold proposal: species have descended from ancestral forms and have been modified to suit their environments.

Darwin and Wallace

______ and ______ both proposed a mechanism of evolution called natural selection.

natural selection

can be broadly defined as an evolutionary process that adapts a population to its environment

On the Origin of Species

In 1859, Darwin laid out the theory of evolution by natural selection in the book __ ____ ___ ___ _____ in which he provided extensive support for the theory.

new

Darwin further observed that when natural selection acts differently on two populations, they may emerge as two ___ species descended from one ancestral population.

allele frequencies

We can define evolution more specifically as a change in _____ _______ of a gene pool.

gene pool

the sum of all the genetic information carried by all the individuals in a population. As the proportion of alleles within the population changes, so, too, do the traits that these genes encode.

(1) Mutation, (2) gene flow, (3) genetic drift, (4) natural selection

Four mechanisms can change the composition of a population’s gene pool:

mutations

are the ultimate source of all genetic variation and are the result of random changes in DNA sequences

random, needs it

Mutations are purely ______ and do not occur because an individual or species “_____ ___.”

Mistakes in DNA replication, Collisions of the DNA molecule with other molecules, Damage from heat or chemical agents

Gene mutations are caused by various accidents such as:

evolution

New mutations that are inherited change the overall genetic composition of the descendant population (change in gene pool), resulting in ______.

alleles, genotype

DNA variants produced by mutation are _____ and the two alleles for each gene in an individual make up the ______ of that individual for that gene.

rare, increase

Although a beneficial mutation is ____, once it is introduced, natural selection can rapidly _____ the frequency of the new allele.

Culex pipiens

Resistance to DDT in _____ ______ mosquitoes is caused by a single mutation.

gene flow

is the movement of genes from one population to another.

migration

A population evolves when there is a change in the gene pool through _______ or out-migration (emigration).

genetic drift

is a random process that can cause the gene pool of a population to change randomly from one generation to the next over time.

genetic drift

______ ____ may cause individuals with a unique set of characteristics to die off while allowing individuals with different characteristics to survive and reproduce.

small, large

Genetic drift is more likely to alter the gene pool of a ____ population than that of a ____ population.

genetic bottleneck

When a drop in the size of a population leads to a loss of genetic variation, the population is said to experience a _____ _______

the founder effect

a type of genetic bottleneck created when a small group of individuals established a new population far from existing populations.

natural population

Individuals in a ______ _________ must compete for resources, such as food, mates, and living space, and avoid predators and defend against pathogens; individuals best able to do so are more likely to survive and reproduce.

natural selection

a nonrandom, directional process that shifts the genetic characteristics of a population in one direction that leads to adaptation over successive generations.

adaptation

The process by which a population as a whole becomes better matched to its habitat over successive generations is known as _______

Adaptive traits

are genetic characteristics that enable the individuals to function well, and therefore survive and reproduce better in a competitive environment

does not

Natural selection ____ ___ craft perfection for all time and all circumstances

1. Directional selection

2. Stabilizing selection

3. Disruptive selection

Individuals with certain forms of an inherited phenotypic trait tend to have better survival rates and to produce more offspring than do individuals with other forms of that trait in all three types of natural selection:

directional selection

When individuals at one extreme of an inherited phenotypic trait have an advantage over other individuals in the population, they exhibit _______ _______

stabilizing selection

When individuals with intermediate values of an inherited phenotypic trait have an advantage over other individuals in the population, they exhibit __________ _______

disruptive selection (fairly uncommon)

When individuals with either extreme of an inherited phenotypic trait have an advantage over individuals with an intermediate phenotype, they exhibit ________ ________

match

Adaptations show a close ____ between organism and environment

Adaptations

help organisms accomplish important functions, such as feeding, defense against predators, and reproduction.

99

Scientists estimate that __ percent of all species that have ever lived are now extinct. Every extinct species is a silent testament to an inability to adapt in the face of adversity.

absence, limit

In some cases the ______ of genetic variation places a direct ____ on the ability of natural selection to generate adaptations in descendant populations.

Ecological trade-offs

_________ ______ ____ may also limit adaptation. To survive and reproduce, organisms must perform many functions, such as finding food and mates, avoiding predators, and surviving challenges posed by the physical environment. However, the conflicting demands that organisms face result in trade-offs, or compromises, in their ability to perform these essential functions.

sexual selection

When individuals differ in inherited characteristics that affect their ability to get mates, they exhibit _____ _____

sexual dimorphism

Sexual selection can lead to _______ ________, which means that males and females are distinctly different in appearance.

Fossils

are the preserved remains, or their impressions, of formerly living organisms, which enable biologists to reconstruct the history of life on Earth

mirrored

The evolutionary and ecological history of some groups is ______ in an almost seamless fossil record that shows organisms changing from ancestral forms to forms that are still present.

Artificial selection

the process by which only individuals with certain inherited characteristics are allowed to breed.

continental drift (or plate tectonics)

The slow movement of the Earth’s continents over time is called:

geographic location

By measuring continental drift, scientists can predict the ________ _______ of fossils, providing another important line of evidence for evolution

population

Evolution is the change that occurs in _____ over time

Adaptations

_________ are often complex. Happen in a stepwise function.

evolutionary past

Patterns of growth in the very earliest stages of life can provide evidence of an organism’s _________ ______.

ancestral

The manner in which an embryo develops, especially at the early stages, may mirror early developmental stages of _______ forms.

more similar

DNA sequences and protein sequences of organisms that share a more recent common ancestor are ____ _______ than those that shared a common ancestor further back in time

B

Of the following situations that pertain to evolution, which one is false? A. Organisms inherit traits from their parents. B. Organisms can adapt to prepare their offspring for future events. C. Evolution can happen by chance.

B

Of the following, which term or phrase best describes the process of natural selection? A. genetic drift B. differential reproductive success C. mutation D. gene flow

B

The average litter size for a squirrel is three. Above and below three is not favored. What type of selection is occurring? A. disruptive selection B. stabilizing selection C. directional selectionB