Is there a word that refer to homologous chromosomes within a polyploid species? If I have AABB species, what is A to B?

The words "homeolog" and "ohnolog" are reserved for the cases if the homologous chromosomes have diverged via speciation or whole genome duplication event. But what if we just don't know?

I hesitate to use word "homologous chromosomes" since they do not for a choromosome pair anymore, they are homologous in sense of an recent common chromosome ancestor.

  • 2
    $\begingroup$ I think homolog is as good a term as you'll get, though I'm certainly not an expert in this area. $\endgroup$
    – canadianer
    Oct 24, 2018 at 23:22
  • 1
    $\begingroup$ In the case of (A+A'+B+B'), A and A' are homologous chromosomes. In canonically sexual species, one is inherited from each parent. "Homeology" applies to chromosomes that are related by ancestral duplication, yet segregate independently at meiosis. en.wikipedia.org/wiki/Homologous_chromosome $\endgroup$
    – J--
    Oct 25, 2018 at 15:25
  • $\begingroup$ @canadianer Hope is the last to die... @J It's the same with ohnologs - they are also expected to segregate independently at meiosis. However "homologous chromosomes" are quite tightly linked to meiosis. $\endgroup$ Oct 25, 2018 at 15:28
  • $\begingroup$ @J-- i think that this comment should be an answer. It is more appropriate IMO than Kamil S Jaron's answer. $\endgroup$ Jan 10, 2021 at 23:28
  • $\begingroup$ @MaximilianPress The main problem of J's comment is that the provided reference doesn't say that homologous chromosomes are defined by shared ancestry, contrary it does say they must pair/segregate in meiosis. $\endgroup$ Jan 11, 2021 at 16:09

1 Answer 1


Unfortunately, there is no such term. Look at Glover et al. 2016 for a proposal how to unify the ploidy related homology terms, none of the words describes exactly what I searched for, so I at least compiled the relevant vocabulary

  • homoeolog/homeolog - homologous chromosomal sets in an organism diverged in isolated populations/subspecies and broght back by a hybridization event; note that the two spellings with exactly the same meaning are possible
  • ohnolog - homologous chromosomal sets originated from a whole-genome duplication (WGD) event; however usually this is used for ancient WGD events (like the R1 and R2 at the base of vertebrates, or the WGD at the base of bony fishes). It is not really possible to distinguish between WGD and hybridization in these ancient cases and therefome ohnologs perhaps suit "unknown" category better.
  • homologous chromosomes - chromosomes that pair during meiosis (does not strictly correspond to the homology in the context of molecular evolution)
  • homologous sequences/homologs - any sequences that have a common ancestor (as used in molecular evolution; but does not have to be on a genome-scale or within a genome; tandem duplicates or orthologs in two species are also homologous sequences)

2020 update:

I asked when I was writing this paper. I needed the term to describe the heterozygosity structure of some polyploids and I ended up calling them homolog (A <-> A' divergence) and homoeolog heterozygosity (AA' <-> BB' divergence) or composite when I was unable to set them apart (the majority of cases in fact).


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