Allopatric speciation is just a fancy name for speciation by geographic isolation, discussed earlier. In this mode of speciation, something extrinsic to the organisms prevents two or more groups from mating with each other regularly, eventually causing that lineage to speciate.
The downside of this is that it can only tell if youâve engaged in drug use in that window. For example, if you smoke marijuana on a daily basis but stop 2-3 days prior to your mouth swab test, the results will probably come back negative. It canât detect prolonged use or the remaining presence of a trace amounts like a urine test can.
Blood testsâ effective ranges will vary based on the half-life of the drug but are generally sensitive for about one to three days.[1] Marijuana edibles will linger longer, for up to seven days. Saliva tests range depending on the drug, but most can detect drugs used in the last 12 hours to three days. Urine tests will also differ depending on the drugâs half-life but can detect most drugs for about two to four days.[2] Drugs that can linger longer include marijuana and PCP.