Answer:
Species separated by a physical barrier for a long time, suffer allopatric speciation, so they can not interbreed anymore.
Explanation:
Allopatric speciation consists of the geographic separation of a continuous genetic background giving place to two or more new geographically isolated populations. These separations might be due to migration, extinction of geographically intermediate populations, or geological events. In this speciation, some barriers impede genetic interchange, or genetic flow, as the two new populations that are separated can not get together and mate anymore. These barriers might be geographical or ecological.
Vicariance is the geographical separation of an original population into two or more new groups. Discontinuities in the physical environment like rivers, mountains, water, etc., are physical barriers that impede genetic flow between the separated groups.
The process of allopatric speciation involves different steps:
- The emergence of the barrier.
- Interruption in the genetic interchange
- The occurrence of new mutations and their accumulation in time in each population. Slow and gradual differentiation.
- Genetic divergence by natural selection and reproductive isolation makes it impossible for the two groups to mate even if the barrier disappears.
- Prezigotic isolation mechanisms favored by selection once occurs a secondary contact between the new species in formation.
Answer:
C. The chance of survival decreases when there is intraspecific competition for resources among surviving yearlings
Explanation:
The survival rate of the offspring of the fish species will decrease as a result of the huge number of eggs produced giving rise to overpopulation. Pressure will be on the limited available resources. As a result of this, Intraspecific competition would occur as members of the same fish species would compete for the limited resources.
Interference and exploitation competition are two types of Intraspecific competition that can reduce the population size of the fish species.
For Interference competition, the dominant and stronger members would secure adequate supply of the limited resources to detriment of the weaker and less dominant ones. This leads to the death of those members that are weak to compete successfully, thereby leading to a reduction in population size.
In exploitation competition, it involves all individual members of the fish species sharing the limited resources equally, while none of them gets an adequate amount. With time, a great size of the population decrease would be noticed when compared to that of Interference competition.
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T cells
The immune response to a transplanted organ consists of both cellular (lymphocyte mediated) and humoral (antibody mediated) mechanisms. Although other cell types are also involved, the T cells are central in the rejection of grafts. The rejection reaction consists of the sensitization stage and the effector stage.
The Law of Conservation of mass is important because then when performing a chemical reaction scientists can determine about the amount of substance that will be produced.
