Module 6 Blog Post : Positive and Negative side of Inbreeding

 Inbreeding is the mating of organisms that are related genetically. Inbreeding is a common phenomenon in natural populations. Inbreeding is not considered an evolutionary force. It has an association with selection. According to the textbook, in inbreeding excess number of homozygotes produces which causes increasing an increase in the probability that individuals are homozygous for recessive deleterious alleles. Recessive deleterious alleles are usually rare. Mating’s that led to individuals with two copies of recessive deleterious alleles are very unlikely homozygotes. That changes when inbreeding becomes common in a population. Along with negative fitness consequences for the individual, the increased probability of combining deleterious recessive alleles also reduces the average fitness in a population, which can be problematic for endangered species. In inbreeding, mating between close relatives in many species yields deleterious outcomes, because blood-relative mating partners have similar DNA, the chances of them carrying the same recessive gene is great increases. In humans, consanguineous mating leads to higher childhood mortality and adverse effects on traits such as lung function and cognitive ability found an example that shows if any species wants to choose a breeding mate based on their preference of inheriting the desired trait it has consequences in long run. Inbreeding may help to inherit certain beneficiary traits to the offspring. At the same time, it reduces the chance of having a diverse gene. Diverse gene helps the offspring survive in the adverse environment and save from being extinct. I found an example; it shows how inbreeding impacted Ancient Egyptian royal mummies. Inbreeding prevented another family from marrying in and lining up to take the throne. A 2015 study examined 259 adult Egyptian mummies and found that royal mummies had consistently different heights from the general population, with male royals being taller than average and female royals being shorter than average.     

the peacock's tail is advantageous in mating. Study shows that peahens choose their mates by the size and shape of his tail. The largest tail indicates a healthy bird and a better chance for healthy offspring. Looks are certainly important for the peacock, with his absurdly bright, burdensome train that he shows off to attract a female.

Peahens often choose males for the quality of their trains, the quantity, size, and distribution of the colorful eyespots. Experiments show that offspring of males with more eyespots are bigger at birth and better at surviving in the wild than offspring of birds with fewer eyespots.
If this way of choosing a mate continues, the offspring will have a bigger and attractive tail. But bigger is only better up to a point. If peacock trains become too big or too colorful over time, they may no longer confer a selective advantage. Exaggerated trains might attract a new kind of predator or become too heavy to carry around. As a result, those super males will die out eventually faster than the ordinary ones.

 Several species have developed inbreeding avoidance mechanisms such as disassortative mate choice or matrilineal group-living where male offspring are ostracized before they reach sexual maturity to limit its effects.

Yengo, L., Wray, N.R. & Visscher, P.M. Extreme inbreeding in a European ancestry sample from the contemporary UK population. Nat Commun 10, 3719 (2019). https://doi.org/10.1038/s41467-019-11724-6

https://www.nature.com/articles/s41467-019-11724-6#citeas

http://www.pbs.org/web/evolution/library/01/6/l_016_09.html

 https://www.nature.com/articles/s41467-019-11724-6

http://www.pbs.org/wgbh/evolution/library/01/6/l_016_09.html

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