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What is the smallest unit upon which natural selection directly acts?

an individual's phenotype

You are maintaining a small population of fruit flies in the laboratory by transferring the flies to a new culture bottle after each generation. After several generations, you notice that the viability of the flies decreased greatly. Recognizing that small population size is likely to be linked to decreased viability, the best way to reverse this trend is to...

cross your flies with flies from another lab

Over time, the movement of people on Earth has steadily increased. This has altered the course of human evolution by increasing

gene flow

"improving the intelligence of an adult through education will result in the adult's descendants being born with a greater native intelligence." This statement is an example of


Darwin's mechanism of natural selection required long time spans in order to modify species. From whom did Darwin get the concept of Earth's ancient age?


Which of the following represents an idea Darwin took from the writings of Thomas Malthus?

populations tend to increase at a faster rate than their food supply

How does the evolution of pesticide resistance occurs in a population of insects?

A number of genetically resistant pesticide survivors reproduce. The next generation of insects contain more genes from the survivors that it does from susceptible individuals.

What anatomical structure is homologous to the wing of a bat?

the arm of a human

As adults, certain species of whales possess baleen instead of teeth. Baleen is used to filter the whales' diet of planktonic animals from seawater. As embryos, baleen whales possess teeth, which are later replaced by baleen. The teeth of embryonic baleen whales are evidence that

baleen whales are descendants of toothed whales

Over evolutionary time, many cave-dwelling organisms have lost their eyes. Tapeworms have lost their digestive systems. Whales have lost their hind limbs. How can natural selection account for these losses?

Under particular circumstances that persisted for long periods, each of these structures presented greater loss than benefits.

What would be the best technique for determining the evolutionary relationships among several closely related species, each of which still contains living members?

DNA or RNA analysis

It has been observed that organisms on islands are different, but closely related to, similar forms found on the nearest continent. This is taken as evidence that

the islands were originally part of the same continent

Upon close examination of the skeleton of an adult python, a pelvic girdle and leg bones can be observed. These features are examples of...

vestigial structures

The theory of continental drift hypothesizes that Africa and South America slowly drifted apart after once being a single landmass. The monkeys on the two continents, although similar, show numerous genetic differences. Which factor was probably important in maintaining these differences?

geographic isolation

Why do some traits, such as thicker fur of flowers of different colors, evolve overtime within a population of organisms?

organisms with these traits survived longer and had more offspring than other organisms in the population, so their trats were passed on to more offspring

What are the five Hardy Weinberg conditions?

no mutaions
random mating
a large population
no gene flow
no natural selection

point mutation

A change in a gene at a single nucleotide pair
these small changes are usually harmful making it less likely for the organism to reproduce but when the mutation has a positive effect on the organism it can enhance reproductive success

gene duplication

over generations these small mutations build up allowing mutations to accumulate and take on new functions

sexual recombination

after each generation alleles rearrange to add variation

What is the relationship between mutation rates and generation spans?

Mutations occur in about 1 gene for every 100,000 in each generation

genetic drift

chance events that cause allele frequencies to fluctuate unpredictably from one generation to the next, especially in small populations

bottleneck effect

Genetic drift resulting from the reduction of a population, typically by a natural disaster, such that the surviving population is no longer genetically representative of the original population.

founder effect

when a few individuals become isolated from a larger population, this smaller group may establish a new population whose gene pool isn't reflective of the source population

gene flow

the transfer of alleles form one population to another, which results in the movement of fertile individuals or their gametes

adaptive evolution

Evolution that results in a better match between organisms and their environment

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