Evolution Warning: You are not logged in. Your IP address will be publicly visible if you make any edits. If you log in or create an account, your edits will be attributed to your username, along with other benefits.Anti-spam check. Do not fill this in! ==== Genetic hitchhiking ==== {{Further|Genetic hitchhiking|Hill–Robertson effect|Selective sweep}} Recombination allows alleles on the same strand of DNA to become separated. However, the rate of recombination is low (approximately two events per chromosome per generation). As a result, genes close together on a chromosome may not always be shuffled away from each other and genes that are close together tend to be inherited together, a phenomenon known as [[genetic linkage|linkage]].<ref>{{cite journal |last1=Lien |first1=Sigbjørn |last2=Szyda |first2=Joanna |last3=Schechinger |first3=Birgit |last4=Rappold |first4=Gudrun |last5=Arnheim |first5=Norm |date=February 2000 |title=Evidence for Heterogeneity in Recombination in the Human Pseudoautosomal Region: High Resolution Analysis by Sperm Typing and Radiation-Hybrid Mapping |journal=[[American Journal of Human Genetics]] |volume=66 |issue=2 |pages=557–566 |doi=10.1086/302754 |issn=0002-9297 |pmc=1288109 |pmid=10677316 |display-authors=3}}</ref> This tendency is measured by finding how often two alleles occur together on a single chromosome compared to [[independence (probability theory)|expectations]], which is called their [[linkage disequilibrium]]. A set of alleles that is usually inherited in a group is called a [[haplotype]]. This can be important when one allele in a particular haplotype is strongly beneficial: natural selection can drive a [[selective sweep]] that will also cause the other alleles in the haplotype to become more common in the population; this effect is called genetic hitchhiking or genetic draft.<ref>{{cite journal |last=Barton |first=Nicholas H. |author-link=Nick Barton |date=29 November 2000 |title=Genetic hitchhiking |journal=Philosophical Transactions of the Royal Society B |volume=355 |issue=1403 |pages=1553–1562 |doi=10.1098/rstb.2000.0716 |issn=0962-8436 |pmc=1692896 |pmid=11127900}}</ref> Genetic draft caused by the fact that some neutral genes are genetically linked to others that are under selection can be partially captured by an appropriate effective population size.<ref name="gillespie 2001" /> Summary: Please note that all contributions to Christianpedia may be edited, altered, or removed by other contributors. If you do not want your writing to be edited mercilessly, then do not submit it here. You are also promising us that you wrote this yourself, or copied it from a public domain or similar free resource (see Christianpedia:Copyrights for details). Do not submit copyrighted work without permission! Cancel Editing help (opens in new window) Discuss this page