Homologs
orthologs/orthologous
(直向同源)：
共同祖先的直接後代(沒有發生基因複製事件)之間的同源基因稱為直向同源。
Orthologs are homologs produced by speciation.
paralogs/paralogous (共生同源)：
兩個物種
A 和 B 的同源基因，分別是共同祖先基因組中由複製事件而產生的不同拷貝的後代，這被稱為共生同源基因。
Paralogs are homologs produced by gene
duplication.
a
A*
b*
c
B
C*
orthologous
orthologous
paralogous
A*
C*
b*
A mixture of orthologues and paralogues sampled
Duplication to give 2 copies = paralogues on the same genome
Ancestral gene
Xenologs are homologs resulting from
horizontal gene transfer between two
organisms.
Synologs are homologs resulting from
genes ended up in one organism through fusion
of lineages
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