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34 Cards in this Set

  • Front
  • Back

what is the best definition of a population?

A group of interbreeding individuals of the same species in a given area

All of the alleles in a population make up the ______.

Gene pool.

How are new combinations of alleles introduced into chromosomes?

crossing over in meiosis I

Traits with more than two distinct forms are ____.


Mutations that result in the death of the individual are known as _____.


A ______ mutation changes the DNA sequence but has no impact on the fitness of the individual.


_______ increases the frequency of adaptive mutations in a population over time.

Natural selection

An allele's abundance within a population is referred to as ______ frequency.


Any change in allele frequencies in a gene pool is called ______.


Environmental pressures result in a(n) ______ of adaptive alleles.

increase in the frequency

What is the original source of new alleles?


With _______ selection, the frequency of a favored allele will increase as a phenotype variation become more adaptive.


Natural selection drives changes in allele frequencies bu influencing traits within a _____ basis.


_____ selection occurs when individuals choose mates with a particular desirable trait.


Fatter sociable weaver birds spend more time foraging where they are vulnerable to predation, are more attractive topredators, and are less likely to escape an attack. Conversely, thin birds risk starvation. Therefore, sociable weaver of anintermediate weight have a selective advantage. This is an example of ____ selection.


In Cameroon, seedcrackers have either small bills (adapted for feeding on soft sedge seeds) or large bills (adapted forfeeding on hard sedge seeds). During competition for scarce resources, these birds primarily feed on the seeds for whichthey are best adapted. This is an example of ____ selection.


Heterozygotes for the sickle cell trait have an adaptive advantage in areas where malaria is prevalent. This is anexample of ____.

a balanced polymorphism

A random change in allele frequency over time that is brought about by chance alone is known as ____.a. genetic drift

genetic drift

Which population is more likely to be affected by genetic drift?

12 squirrels in a forest

Overhunting of species, such as tigers, reduces their numbers and their genetic diversity. This is an example of _____.

a bottleneck

The Old Order Amish in Lancaster County is descended from one man and woman and has an unusually highfrequency of a recessive allele that causes Ellis-van Creveld syndrome. This is an example of ____.

a founder effect

The movement of alleles among populations is called _____.

gene flow

In the universal ABO blood grouping system, there are four phenotypes - A, B, AB, and O - which are determined bythree different alleles. The presence of three alleles in the ABO blood grouping system is an example of ____.

a polymorphism

What is one result of the bottleneck effect?

decreased genetic diversity

The process of speciation always includes ____ isolation.


Two species of toads have been successfully interbred in a laboratory but do not hybridize in nature because onespecies mates in summer and the other mates in the fall. This is an example of ____ isolation.


In Lake Victoria, hundreds of cichlid fish species arose after the lake last dried up 12,400 years ago. This is anexample of ____.

sympatric speciation

. In the 16th century, a Spanish ship explored a Pacific Island that had a small mountain range separating it. Mice thatwere on the ship escaped onto the island on both sides of the mountain range. After decades of separation the twopopulations developed different numbers of chromosomes, resulting in reproductive isolation that prevented any futureinterbreeding. This speciation event is an example of ____.

allopatric speciation

Over evolutionary time, flowering plants have evolved colors, odors, and nectar that attract pollinating insects and theinsects have evolved mechanisms that detect the changes in plants and to better collect pollen. This is an example of ____.


The appearance of lungs was a(n) ____ that drove the evolution of land vertebrates.

key innovation

When a physical barrier separates a population, leading to the evolution of new species on either side of the barrier,____ has occurred.

allopatric speciation

A major change in evolutionary patterns over long periods of time is best described as ____.


The emergence of hundreds of Hawaiian honeycreeper species from a single flock introduced to this islandarchipelago millions of years ago is an example of ____.

adaptive radiation

A ____ is a structural modification that enables an individual to exploit their habitat more efficiently.

key innovation