Updated 05-May-2020.
Mondo shtuff from around the internet, all about GENE FLOW!
My botty best at summarizing from Wikipedia: gene flow is a transfer of genetic variation from one population to another . it takes only “One migrant per generation” to prevent populations from diverging due to drift . migrants change distribution of genetic diversity within populations gene flow thought to constrain speciation by combining gene pools of groups . gene flow expected to be lower in species that have low dispersal or mobility . migration may also result in the addition of novel genetic variants to gene pool highly mobile individuals tend to have greater migratory prospects . pollen and seeds may be carried great distances by animals or wind . when gene flow is impeded, there can be an increase in inbreeding lack of gene flow has led to high rates of inbreeding . gene flow measured by using effective population size and net migration rate per generation . effect of migration can be calculated for a population in terms of degree of genetic when there is less than 1 migrant per generation (no migration) the inbreeding coefficient rises rapidly resulting in fixation and complete divergence ( F S T displaystyle F_ST physical barriers to gene flow are usually, but not always, natural . they may include impassable mountain ranges, oceans, or vast deserts . in some cases, they can be artificial, man-made barriers, such samples of the same species which grow on either side have developed genetic differences . there is little to no gene flow to provide recombination of the gene pools . this is because Ulmus pumila has wind-pollin gene flow between hybrid and wild populations can result in loss of genetic diversity . genetic differentiation can also result from endogamy, due to differences in caste, ethnicity, customs and religion . when a species exist in small nonnative species can threaten native plants and animals with extinction . hybridization and introgression can bring previously isolated species into contact . rare species coming into contact with more abundant ones . interbreeding between species can cause a ‘swamping’ of rarer species’ gene pool . this can create hybrids that supplant the native stock . the extent of this phenomenon is not always urban facilitation model suggests gene flow is enabled by anthropogenic changes to the landscape . it connects populations, reduces isolation, and increases gene flow into an area which would otherwise not have this specific genome composition . human-driven climate change is another mechanism by which southern-dwelling animals might be forced northward towards cooler temperatures . humans are known to introduce non-native species into new environments, which could lead to hybridization . urban spiders are larger, darker, and more aggressive, which could lead to increased survival in urban environments . western black widow spiders have highly toxic venom and pose risks for human health . rising global temperatures push bobcat populations into northern territory . increase in human activity also enables bob cat migration northward . increased human activity brings increased roads and traffic, but also increases road maintenance, plowing, and snow comp positive effects of urban facilitation can occur when gene flow enables better adaptation and introduces beneficial alleles, and would ideally increase biodiversity . negative effects would occur when increased gene flow is maladaptive and causes the loss of beneficial bacteria can incorporate genes from dead bacteria, exchange genes with living bacteria, and can exchange plasmids across species boundaries . “the original metaphor of a tree no longer fits the data from recent genome research”. biologists should instead use the metaphor of a mosaic to describe the different histories combined in individual genomes . “it is difficult to trace organismal phylogeny in the presence of HGT,” says nadine hybridization occurs because some traits and DNA are more readily exchanged . hybrids are generally deemed less “fit” than their parental generation . the ultimate goal in conservation genetics is to maintain the genetic integrity of a species Darwin’s finches likely experienced allopatric speciation in some part due to differing geography . but that doesn’t explain why we see so many different kinds of finches on the same island . this is due to the marine iguana is an endemic species of the Galapagos Islands . gene flow between the two species was limited due to geographic isolation . they evolved to adapt to the island environment . single origin theory assumes that there was a common ancestral population originating in Africa of Homo sapiens . this theory minimizes the amount of parallel evolution that is needed . comparisons between sympatric and allopatric a 2014 study found that high levels of genetic diversity and low levels of inbreeding were estimated in the breeding centers . plants: two populations of monkeyflowers were found to use different pollinators that limited gene flow,