Answer:
a. a portion of the population becomes isolated from the remainder of the population and experiences different selective pressures
Explanation:
This is an example of allopatric speciation Allopatric speciation is a form of speciation (formation of new species) that occurs as a result of geographic isolation. This means that a part of population becomes physically separated from the initial main population. There is no gene flow between these two populations and as a result the two populations reach a high level of genetic divergence. They can no longer interbreed which means they become two different species (speciation).
New populations evolve as result of mutation, genetic drift and natural selection.
For example, Galapagos finches are isolated from others by the ocean (geographic isolation). Because of the isolation, the finches don’t breed with one another. So, they developed unique characteristics and became endemic.
<span>Damming a river has a variety of effects on the freshwater ecosystem, more than just altering the flow from A to B. Dams create calm bodies of water, changing overall temperature regimes and sediment transport, leading to conditions which tend to favour generalist species. Loss of specialist species, particularly endemics, changes the community structure and leads to biotic homogenization. A dam will withhold sediment in the reservoir, not just decreasing the amount of substrate available to local freshwater species, but even impacting diadromous, estuarine and marine species much further downstream. The competition between resident species for food and breeding sites will increase as damming isolates populations, and perhaps more importantly, damming completely restricts migratory fish species. Isolation may lead to decreases in genetic diversity and therefore puts species at greater risk from disease. All of these effects may be exacerbated by changes in the surrounding land use. Overall, damming river flow will lead to both a loss of native species, but also an increase in exotic species which are more likely to become established in degraded habitats. For this reason, dams are one of the greatest global threats to freshwater biodiversity.</span>
Answer:
The answer is 97%.
Explanation:
The zika virus' 1% incidence rate in the population has no effect over the probability of the patient being infected or not. If the test has a 3% false positive rate that means that if it is positive, the results have a 97% chance of being true. Therefore the chance that the person who took the test and had a positive result being actually infected is 97%.
I hope this answer helps.
Answer:
D. Sun > Grass > Mouse > Owl
Explanation:
the arrows show the flow of energy; in other words they show who is receiving the energy
