The northern elephant seal was hunted almost to extinction during the 18th and 19th centuries. Less than 100 seals were left to contribute to the gene pool of their future generations. Since the early 20th century, the elephant seals have been protected by law in both the U. S. and Mexico. Over 100,000 seals now inhabit the western shores of North America, all related to the small population that survived the slaughter of hunters. Scientists fear the elephant seals may be more susceptible to disease and pollution due to a .A. heterozygous advantageB. disruptive type of selectionC. Founder EffectD. Bottleneck Effect

The correct answer is option D, that is, bottleneck effect.

Explanation:

A phenomenon, which occurs due to events like earthquakes, floods, or other natural calamities that result in the severe declination in the size of a particular population is known as the bottleneck effect. The bottleneck effect is an extreme illustration of genetic drift that results in the reduction of a population's genetic variability.  

With the decline in the size of a specific population, a reduction in the genetic variability of the same population is witnessed due to the loss of alleles. This eventually makes the population vulnerable to pollution and diseases. Hence, the given case is an example of the bottleneck effect.  

from almost the creation of the first true maps of the earth, people started seeing how continents would be able to fit together.   in particular, people noticed that south america fits almost exactly into africa.

you should be aware that while world maps were around early in the 1600’s and better defined by the end of the 1700’s, those maps were not ‘public’ but were treated as state secrets.   and so it was not till much later that the broader ‘science’ community had access to good quality and accurate world maps.

get the whole story here…

it is now known that most of the major continental masses can be fit together in a jigsaw process.   in fact we now know that the continents were indeed once all joined together as one land mass – the supercontinent of pangaea.

if you look at most world maps you will ponder how this is evidence, as the continents really don’t appear to ‘fit’ together very well.   what you need to understand is that the vast majority of maps are drawn using a map projection that has the north and south poles (which are points) are a line the width of the map at the top and bottom.   this means that the map distorts the true shape of the earth’s land and oceans as you love closer to the poles.     some other map projections distort less, but have the map shape looking like segments of an orange.   see here for a range of map projections.   check out the way greenland changes size in each!

what is more remarkable, is the next piece of evidence when added to the shape of continents.

location of mountains and fossils

what is remarkable, when you reassemble all the continents together, the ancient mountain ranges (many now eroded to their cores) and the location of rock types and fossils all match up.

answers are:

lysogenic     viral dna merges with host cell dna

lysogenic     no symptoms

lytic               viral dna takes over

lysogenic     virus does not destroy host cell

lytic               virus destroys host cell

lytic               induces symptoms of viral infection

lysogenic       cell reproduces and spreads provirus