Fig. 1
From: Inferring synteny between genome assemblies: a systematic evaluation
Definition of synteny block and break. Genes located on chromosomes of two species are denoted in letters. Each gene is associated with a number representing the species they belong to (species 1 or 2). Orthologous genes are connected by dashed lines and genes without an orthologous relationship are treated as gaps in synteny programs. Under the criterion of at least three orthologous genes (anchors): a synteny block can be orthologs with the same order (block a), with reversed order (block b), or allowing some gaps (block c). In contrast, cases of causing a synteny break can be lack of orthologs (break a), co-arranged gene order (break b) or gaps (break c)