Species evolve independently possibly due to geographical isolations or behavioural isolations.
Geographical isolation includes the isolation of 2 groups of the same species. Since these 2 groups live in different locations, (e.g. a volcanic eruption resulting in a barrier between one side of an ocean and another side of the ocean), they will have different selection pressures in their different environments as well (e.g. one side of the ocean may have more sunlight and thus more underwater plantations than the other side of the ocean). Natural selection will eliminate those with disadvantageous characteristics (e.g. Fishes that only eat plants and nothing else on the side of the ocean with little plantations) with unfavourable alleles, and select for those with advantageous characteristics (e.g. Fishes are able to eat plants and other organic substances as well on the side of the ocean with little plantations) with favourable alleles.
Since the 2 groups have different selection pressures, natural selection will occur in different ways, selecting for and against different types of fishes with different types of alleles. Also, because of the barrier, they are not able to mate with each other, and there are no mixing of genes from one side of the ocean and the other side. They are genetically isolated. As genetic drift occurs over time, their gene pools become different from each other. Thus, they evolve independently.
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Whales use their lower jawbone to the middle ear. whereby they can ear clearly while they are in the water. Human ears and dolphins ears they work the same . They receive sound directly from the air.
In similar way dolphins and human ears are placed in basic anatomical location which is same as on the head. Without a medium hearing is not possible.
The medium sound for human is air. Sound travels 343 meters per second in air and 147 meters per second in water. The most effective way of transmitting sound waves is through water.
We can say that the sound will be fast to travel in medium if the molecules are closer.
Table 1: The horizontal pulling forces (F) and resulting acceleration (a) for the cart.
The cart experiences no motion when there is 0.1 N of horizontal force, so F=0 in this case. When one uses Newton's Second Law to find the acceleration caused by each force, it becomes clear that every row in the chart represents a horizontal force of approximately F=20 N. The best fit for the missing value is F=-30N.
Answer:
Microtubules play an important role in cell division by contributing to the formation of the mitotic spindle, which plays a part in the migration of duplicated chromosomes during anaphase.
