【作者】 王林云；

【Author】 Linyun Wang (Nanjing Agricultural University,Nanjing 210095)

【机构】 南京农业大学；

【摘要】 物种是生物分类中的基本单位。在同一物种内,某一个体是"纯种"?还是"杂种",是相对的。一个生物是纯种或是杂种,需要有一个参照生物体。生物个体B是否是纯种,必须有一个同物种(或品种)的纯种个体A作为参照生物体。当B的DNA中单核苷酸序列与A的DNA中单核苷酸序列完全相同时,可以说,它与A是同一物种(或品种)的纯种。从"核苷酸序列"的角度说,地球上的每个人和动物都是杂合体,或可称为"杂种"。也可以说,地球上没有两个人是完全相同的,没有两头猪是完全相同的。配猪生猪,子猪似亲猪,子猪非亲猪。同一物种内两个生物体之间的交配可视为"杂交",称之为"杂合体之间的杂交"。同一物种内的生物体为了自己的繁衍与世代延续,总是在不断的杂交。这种亲代间的杂交会引起子代核苷酸序列的轻微变异,这种轻微的改变,多数情况下,不会改变生物的主要性状。当这种变异积累到一定程度,又引起更多、更大的变异,特别在某些核苷酸序列的关键位点发生改变,有时甚至只要有一个核苷酸被置换,就有可能改变生物的某些性状。本文对同一物种内生物个体种质的"纯"与"杂"的相对性及一个新物种的形成过程进行了阐述。更多还原

【Abstract】 Species is the basic unit of biological classification.A biological individual is a"pure"or"hybrid"is relative within the same species.To estimate a biological individual is pure or hybrid needs a control biological individual.Whether a biological individual B is purebred,there must be a same species of individual A as a control.When the B’s DNA is the same as the A’s DNA,you can say B and A are the same purebred.From"nucleotide sequence"point of view, every human and animal on Earth is heterozygous,or can be called"hybrid."Can also say that no two people on Earth are the same,no two pigs are exactly the same.Boars and sows mating gave birth to piglets,piglets are similar,but different with their parents.Within the same species, mating between two individuals can be considered"hybrid",called"a cross between two heterozygotes."Within the same species for their own reproduction and to future generations, they are always hybrid.This hybrid between parents will cause minor variations of nucleotide sequence.This slight change,in most cases,will not change the main characters of this specie. When this mutation accumulation to a certain extent,then lead to more and greater variation, particularly in some key sites of nucleotide sequence changes,sometimes as long as a single nucleotide is replaced,it is possible to change some of the characters.This article on the theory of relativity of"purebred"or"hybrid"within the same specie and the formation of a new specie are described.更多还原