Evolution Mock Tests

Adaptive radiation is most classically demonstrated by which of the following examples?

The following passage is an excerpt from an article about evolutionary biology. Speciation is the process by which new species arise from existing ones. A species, in the biological species concept most commonly taught, is a group of organisms that can interbreed and produce fertile offspring. For speciation to occur, populations of a species must become reproductively isolated—meaning they can no longer exchange genetic material. Reproductive isolation can be prezygotic (occurring before fertilization) or postzygotic (occurring after fertilization). Prezygotic barriers include habitat isolation (populations live in different habitats and rarely encounter each other), temporal isolation (populations breed at different times), behavioral isolation (populations have different mating rituals), mechanical isolation (physical incompatibility of reproductive structures), and gametic isolation (sperm and egg are incompatible). Postzygotic barriers include reduced hybrid viability (hybrid offspring do not develop properly or are weak), reduced hybrid fertility (hybrids are sterile, as in the case of mules, which are sterile offspring of horses and donkeys), and hybrid breakdown (the first-generation hybrids are viable and fertile, but their offspring are weak or sterile). Allopatric speciation occurs when a population is divided by a geographical barrier, such as a mountain range, river, or ocean, preventing gene flow between the separated groups. Over time, genetic drift and natural selection in the different environments cause the populations to diverge genetically, and eventually they become reproductively isolated even if the barrier is removed. Sympatric speciation, in contrast, occurs without geographical separation: a new species evolves from a single ancestral species while inhabiting the same geographic region. Sympatric speciation can occur through mechanisms such as polyploidy (having extra sets of chromosomes, common in plants), habitat differentiation, and sexual selection. Polyploidy is particularly important in plant speciation: a duplication of chromosomes can produce an instant reproductive barrier, as the polyploid individual can no longer produce fertile offspring with its diploid parents. According to the passage, what is allopatric speciation?

A population of 1,000 individuals is in Hardy-Weinberg equilibrium. If the frequency of the recessive allele (q) is 0.4, how many individuals are expected to be heterozygous:

The following passage is an excerpt from an article about evolutionary biology. Darwin's theory of natural selection rests upon several observable facts and their logical consequences. First, populations produce more offspring than the environment can support, leading to a struggle for existence. Second, individuals within a population exhibit variable traits, many of which are heritable. Third, individuals with traits better suited to their environment are more likely to survive and reproduce, thereby passing those advantageous traits to the next generation. Over successive generations, this differential survival and reproduction results in the gradual accumulation of favorable characteristics within the population. However, natural selection acts only on existing variation; it cannot generate new traits on demand. New genetic variation arises through random mutations and recombination, which provide the raw material upon which selection operates. Furthermore, natural selection does not lead to perfect organisms, as environmental conditions change, trade-offs exist between different traits, and genetic drift may counteract selective pressures. According to the passage, why does natural selection not produce perfectly adapted organisms?

Co-evolution between a predator and its prey typically results in an "evolutionary arms race" characterised by:

Genetic drift causes changes in allele frequencies primarily in:

The Hardy-Weinberg principle states that allele frequencies in a population remain constant under which condition:

A population of beetles has two color variants: green and brown. A flock of birds regularly feeds on these beetles, easily spotting the green ones against the brown bark. Over several generations, the frequency of brown beetles increases. This scenario best illustrates: