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Population bottleneck followed by recovery or extinction. A population bottleneck or genetic bottleneck is a sharp reduction in the size of a population due to environmental events such as famines, earthquakes, floods, fires, disease, and droughts; or human activities such as genocide, speciocide, widespread violence or intentional culling.
Intercellular ("between cells") selection occurs on a larger scale, and refers to the preferential growth of cells that have greater numbers of a certain mitochondrial genotype. [8] Selective differences can occur between naturally occurring, non-pathological mtDNA types when mixed in cells, and may depend on tissue type, age, and genetic ...
The impact of a population bottleneck can be sustained, even when the bottleneck is caused by a one-time event such as a natural catastrophe. An interesting example of a bottleneck causing unusual genetic distribution is the relatively high proportion of individuals with total rod cell color blindness ( achromatopsia ) on Pingelap atoll in ...
A bottleneck can reduce or eliminate genetic variation from a population. Further drift events after the bottleneck event can also reduce the population's genetic diversity. The lack of diversity created can make the population at risk to other selective pressures. [36] A common example of a population bottleneck is the Northern elephant seal ...
Male expendability, the relative expendability argument, or the expendable male hypothesis, is the idea that the lives of male humans are of less concern to a population than those of female humans because they are less necessary for population replacement.
The most notable components of the cell that are targets of cell damage are the DNA and the cell membrane.. DNA damage: In human cells, both normal metabolic activities and environmental factors such as ultraviolet light and other radiations can cause DNA damage, resulting in as many as one million individual molecular lesions per cell per day.
Biotic homogenization is the process by which two or more spatially distributed ecological communities become increasingly similar over time. This process may be genetic, taxonomic, or functional, and it leads to a loss of beta (β) diversity. [1]
The founder effect occurs when a small group of migrants—not genetically representative of the population from which they came—establish in a new area. [4] [5] In addition to founder effects, the new population is often very small, so it shows increased sensitivity to genetic drift, an increase in inbreeding, and relatively low genetic ...