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.
This is the reason that drug tests, namely urine tests, look for 9-carboxy-THC. Many of the following numbers are estimates. Typical Periods of Time that Marijuana Use May be Detectedâ¡. â¡ Some private companies may use hair tests to detect possible marijuana use.The detection period for 9-carboxy-THC in urine may be as long as three months in extremely heavy users. Research on saliva tests indicated that they may be able to detect THC up to eight hours after ingestion but they aren't widely used.