Natural selection, which includes sexual selection, is the fact that some traits make it more likely for an organism to survive and reproduce. Population genetics describes natural selection by defining fitness as a propensity or probability of survival and reproduction in a particular environment. The fitness is normally given by the symbol w=1-s where s is the selection coefficient.
Atrial fibrillation with RVR (Rapid Ventricular Response) is a heart condition caused by irregular electrical activity that results in irregular contractions of the heart walls and its chambers. The heart (atrium), shakes with a rapid tremulous movement or makes fine irregular twitching movements, generally referred to as fibrillating.
Introduction. Atrial fibrillation is a heart condition that causes an irregular and often abnormally fast heart rate. A normal heart rate should be regular and between 60 and 100 beats a minute when you're resting.You can measure your heart rate by feeling the pulse in your neck or wrist.ntroduction. Atrial fibrillation is a heart condition that causes an irregular and often abnormally fast heart rate. A normal heart rate should be regular and between 60 and 100 beats a minute when you're resting.