Causes of speciation
<span>Geographic isolation
In the fruit fly example, some fruit fly larvae were washed up on an island, and speciation started because populations were prevented from interbreeding by geographic isolation. Scientists think that geographic isolation is a common way for the process of speciation to begin: rivers change course, mountains rise, continents drift, organisms migrate, and what was once a continuous population is divided into two or more smaller populations.
</span>Reduction of gene flow
<span>However, speciation might also happen in a population with no specific extrinsic barrier to gene flow. Imagine a situation in which a population extends over a broad geographic range, and mating throughout the population is not random. Individuals in the far west would have zero chance of mating with individuals in the far eastern end of the range. So we have reduced gene flow, but not total isolation. This may or may not be sufficient to cause speciation. Speciation would probably also require different selective pressures at opposite ends of the range, which would alter gene frequencies in groups at different ends of the range so much that they would not be able to mate if they were reunited.</span>
<span>Serum potassium, phosphate, calcium
and magnesium concentrations will not directly suggest intrarenal acute renal
failure. The confirmatory test for acute renal failure is the ratio of serum
creatinine and blood urea nitrogen (BUN). </span>They serve as indicators of decrease
renal function when there is a small amount of waste products primarily blood
urea nitrogen and creatinine found in the blood of the patient. Moreover, the
decline measurement of these two serum in the blood will be use for the
diagnosis of intrarenal acute renal failure.
Bicarbonate buffer system. Human blood contains large amounts of carbonic acid, which is a weak acid, and bicarbonates, a strong base. If blood pH falls below 6.8 or rises above 7.8, one can become sick or die. This bicarbonate buffer system help maintain blood pH at 7.4. The bicarbonate neutralizes excess acids in the blood while the carbonic acid neutralizes excess bases.
Answer is: yes, it is <span>possible to be </span>reinfected<span> with the norovirus.
</span>Noroviruses ( food poisoning) are cause of acute gastroenteritis - diarrhea and vomiting. People are infected with noroviruses when they eat or drink contaminated foods and liquors. <span>Once someone </span><span>caught </span>norovirus<span>, </span>they<span> are immune to the illness for around 14 weeks.</span>
