6.2 Inbreeding
What are some benefits of inbreeding that may lead to the evolution of assortative mating? What are some of the costs of inbreeding that may have prompted to evolution of inbreeding avoidance (disassortative mating)?
Inbreeding can be seen in a few species, such as Mangrove Killfish, some plants, and endangered species. Inbreeding can lead to assortative mating, where individuals with similar genotypes mate to produce offspring. I could see this as being potentially beneficial if the traits that the individuals have are favorable, and allow the species to survive and thrive in the environment they're in. Assortative mating can evolve as more and more individuals are produced from inbreeding, therefore the offspring simply do not have anyone else to mate with, since all the possible mates have similar genotypes. We can see inbreeding in endangered species, which in turn could continue to produce that species and help fight endangerment. But, it's not a given that these offspring produced will have the same fitness or overall survivability as the parents, because a lot of funky stuff can happen when inbreeding occurs.
Inbreeding does not change the allele frequency, therefore evolution does not occur. I feel that some costs of inbreeding that led to disassortative mating could have been that they were not surviving well by inbreeding. If the individuals produced from inbreeding were not surviving, they might seek out other partners to introduce some variability in the population. I also feel that disassortative mating can come about if the females cannot obtain viable offspring from the same-genotype-partner she is trying to mate with. If this is the case, the female will seek other mates to be able to reproduce. This would lead to variation in the genotype, therefore eliminating some inbreeding.
Hey Allie! I appreciate that you pointed out how common inbreeding is in endangered species. This just goes to show that conservation biologists have an important job of making sure that a species with limited genetic diversity is equipped to handle changes in their environment such as introduction of disease. After you pointed out that funky stuff can happen when inbreeding occurs, I first thought of the introduction of recessive diseases when two heterozygotes mate. Were you able to think of other issues that arise from inbreeding? Additionally, in my own blog, I also talked about how important disassortative mating is for keeping genetic diversity within a population. Genetic diversity helps populations evolve more quickly in changing environments due to the ability to select for alternative alleles. Thank you for also sharing that inbreeding is not evolution. It increases the ratio of homozygotes but not the actual allele frequencies.
ReplyDeleteAllie, I am so glad you distinguished that inbreeding is not an evolutionary mechanism! While it can maintain traits, it does not introduce variability that could lead to evolution. You are absolutely right when you said that disassortative mating could have resulted from individuals not surviving well after utilizing inbreeding. In my blog post, I talked about a royal family that ruled most of Europe over the last 600 years. Their inbreeding led many of their children to be sterile, so they couldn't even produce an heir to keep the legacy going!
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