AP Biology : Speciation
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Example Question #11 : Understanding Reproductive Barriers
Which of the following is true regarding speciation?
Allopatric and sympatric speciation are two major types of speciation
Barriers to reproduction are critical in speciation
It is an outcome of evolution
All of these
All of these
Speciation is a process in which one species diverges into two. Two major types of speciation are allopatric and sympatric speciation, with each type featuring a unique barrier to reproduction that halts genetic exchange between populations.
Example Question #1622 : Ap Biology
Which of the following is not an example of a reproductive barrier?
Two species of cicada live in the same area. Species A is sexually mature every 7 years. Species B is sexually mature every 2 years.
For a certain species of walrus, males defend large groups of females called harems. Typically, one male's harem will consist of about 20 females, and he will mate with all of them. Some male walruses don't have harems.
Horses and donkeys are different species, but can breed with each other to produce mules. However, mules are sterile (they cannot have offspring of their own).
Two species of birds live in the same area. Species A has dull gray plumage and has developed an elaborate courtship dance. Species B has vibrant orange plumage and has no courtship dance. Females from Species A choose mates based on their dance, and females from Species B choose mates based on their plumage.
For a certain species of walrus, males defend large groups of females called harems. Typically, one male's harem will consist of about 20 females, and he will mate with all of them. Some male walruses don't have harems.
A reproductive barrier is something that prevents two populations from interbreeding, eventually leading to speciation. The cicada populations are an example of temporal isolation--the two species do not interbreed because they do not breed at the same time. The horse and donkey example shows hybrid sterility--the two species can produce offspring, but the offspring cannot have offspring of their own. The bird species are an example of behavioral isolation--the two species have different courtship rituals (dance vs. plumage) which leads to minimal interbreeding.
Example Question #12 : Understanding Reproductive Barriers
Which of the following is an example of a post-zygotic reproductive barrier?
Two species of toads do not interbreed because one species breeds in the summer and the other breeds in the spring.
Two species of beetle do not interbreed because the males have different pheromones.
Two species of sticklebacks do not interbreed because one species lives in fresh water and the other lives in coastal estuaries.
A horse and a donkey breed successfully to produce a mule, which is sterile.
A horse and a donkey breed successfully to produce a mule, which is sterile.
A post-zygotic reproductive barrier occurs after fertilization has occurred. That is, the two individuals have already mated but either the offspring has died or it is sterile. A pre-zygotic barrier occurs before fertilization occurs. Pre-zygotic barriers are those that prevent individuals of different species from mating in the first place.
Example Question #13 : Understanding Reproductive Barriers
There was once a population on planet M311, called the Freg, who lived on a planet not unlike Earth. At the height of the Fregs technology and evolution, a collection of asteroids bombarded the planet and the devastation was so great that the planet was split in two, as was the Freg population. Much of the Freg population died, but many still survived on both pieces of M311.
Thousands of years ago, the environment on M311 was almost entirely dry and the Freg had evolved to suit that environment. Over time, the environment became more water-based and the Freg developed webbed feet and gills. However, as a result of the asteroid catastrophe, the climate returned to a more hot, dry, desert-like climate. As a result, the Freg began to to lose their webbed feet and gills. What is this process called?
Anti-evolution
Devolution
Amphibiatory genesis
Regressive growth
Hydrocorporeal restoration
Devolution
The correct answer to this question is devolution. Devolution refers to when a species reverts to an earlier, more primitive physical form as a result of environmental demands.
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