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The Population Reference Bureau (PRB) Country ranking and comparison by TFR: 1970 and 2013 list is sourced and based on the data of the 2014 World Population Data Sheet, [16] which was published online. [17] [18] Forecast/prediction ranking lists: The UN ranking list is sourced from the United Nations World Population Prospects. Figures are ...
A 2023 map of countries by fertility rate. Blue indicates negative fertility rates. Red indicates positive rates. The total fertility rate (TFR) of a population is the average number of children that are born to a woman over her lifetime, if they were to experience the exact current age-specific fertility rates (ASFRs) through their lifetime, and they were to live from birth until the end of ...
Inbreeding is also used to reveal deleterious recessive alleles, which can then be eliminated through assortative breeding or through culling. In plant breeding, inbred lines are used as stocks for the creation of hybrid lines to make use of the effects of heterosis. Inbreeding in plants also occurs naturally in the form of self-pollination.
For example, adaptation to changing environmental conditions often causes relevant genetic changes during inbreeding. Furthermore, if inbreeding is due to a reduction in population size, selection against new deleterious mutations can become less efficient, and this can induce additional fitness decline in the medium-long term.
The birth rates [1] and death rates [2] in columns one and two are the CIA World Factbook estimates for the year 2022 unless otherwise noted, rounded to the nearest tenth (except for Mayotte and the Falkland Islands with 2010 and 2012 estimates respectively). The natural increase rate in column three is calculated from the rounded values of ...
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.
When a species exist in small populations there is an increased risk of inbreeding and greater susceptibility to loss of diversity due to drift. These populations can benefit greatly from the introduction of unrelated individuals [11] who can increase diversity [16] and reduce the amount of inbreeding, and potentially increase population size. [17]
A graphical representation of the typical human karyotype The human mitochondrial DNA. Human genetic variation is the genetic differences in and among populations.There may be multiple variants of any given gene in the human population (), a situation called polymorphism.