A gene polymorphism can be defined as the existence of two or more variants of the same gene (i.e., alleles). A polymorphism may be a difference of one nucleotide base in DNA (single nucleotide polymorphisms, SNPs) or indels (i.e., insertions and deletions). A gene under selection will have many polymorphisms in its sequence which may lead to convergence and disproportionate divergence among sequences, and thereby will be uninformative to trace the evolutionary history among individuals within a species, population, etc. Conversely, neutral molecular markers exhibit fewer nucleotide differences, it is for that reason that they are commonly used to determine genetic population structure among individuals.
In plants, hormones travel large throughout the body via the vascular tissue (xylem and phloem) and cell-to-cell via plasmodesmata. In contrast, many animal hormones are produced only in specific glands. Plants do not have specialized hormone-producing glands.
