Systemic lupus erythematosus, often abbreviated as SLE or lupus, is a systemic autoimmune disease (or autoimmune connective tissue disease) in which the bodyâs immune system mistakenly attacks healthy tissue.ystemic lupus erythematosus, often abbreviated as SLE or lupus, is a systemic autoimmune disease (or autoimmune connective tissue disease) in which the bodyâs immune system mistakenly attacks healthy tissue.
Natural selection will only cause evolution if there is enough genetic variation in a population. Before the discovery of Mendelian genetics, one common hypothesis was blending inheritance. But with blending inheritance, genetic variance would be rapidly lost, making evolution by natural selection implausible.
Mechanisms of Evolutionary Change. Microevolution (evolution on a small-scale) refers to the changes in allele frequencies within a single population. Allele frequencies in a population may change due to four fundamental forces of evolution: Natural Selection, Genetic Drift, Mutations and Gene Flow. Mutations are the ultimate source of new alleles in a gene pool. Two of the most relevant mechanisms of evolutionary change are: Natural Selection and Genetic Drift.