Answer:
Fourth Stage
Explanation:
During the fourth stage of demographic transition, the birth rates with in a population fall below the level of replacement and thus the population of such countries starts shrinking. This was once a common scenario in countries like Japan, Italy and Germany. The economy sees a down fall as the ageing population increases with no replacement of it in near by future.
Mostly the developed nations after the post industrial age are facing this situation.
effect.
B. Disruptive selection divides a population into two new species.
C. Selective breeding creates a new species of dog.
D. A mutation spreads rapidly through a small population.
The example of genetic drift is A. The allele frequency of a population changes due to a bottleneck effect.
Genetic drift refers to random fluctuations in the frequency of alleles (variants of a gene) in a population over time. This can occur due to various factors, such as a reduction in population size or migration of individuals between populations.
The bottleneck effect is a type of genetic drift that occurs when a population experiences a sharp reduction in size, which can reduce the genetic diversity of the population. This can result in certain alleles becoming more common or being lost altogether, even if they were not necessarily more advantageous or disadvantageous for survival.
Disruptive selection (option B) and selective breeding (option C) are mechanisms of natural and artificial selection, respectively, and do not necessarily involve random fluctuations in allele frequencies.
Hence, A mutation spreading rapidly through a small population (option D) could be an example of genetic drift if it results in a change in allele frequency, but the fact that it spreads rapidly suggests that it may be under the influence of natural selection instead.
Learn more about genetic drift at :
#SPJ7
B.biotic
C. habitat
D.abiotic
1. Location of mountains and fossils
The ancient mountain ranges (many now eroded to their cores) and the location of rock types and fossils all match up. Earthquakes and Volcanoes, If we map the location of all the earthquakes recorded over time, almost all of them occur along what we recognize as plate boundaries.
2. The Earth’s magnetic = field flips every few hundred thousand years, and the stripes on the ocean floor show a record of those changes. By estimating when the flips occurred and pairing that with the distance the strips have moved from the spreading zone, scientists can estimate how fast the continents are moving.
3. Direct Measurement = Modern technology gives us a range of ways to directly measure the movement of tectonic plates. These methods are based around the idea of measuring distance between two points on Earth by using some intermediary transmitter in space. For example, SLR (Satellite Laser Ranging) uses two lasers on Earth, each of which fires a laser to a satellite orbiting the planet.