Are genetic sequences the only way to determine species relations?

[Jekertee]

A very simple question I am struggling about, I don't know how to determine two species are related. Is it only the similarity in the genetic sequences ?

Thanks

 

[Jekertee]

I think I should ask ALL of my questions so that I won't keep asking

that,

Is there also a strange problem as when 3 or 4 species having the same degree of similarity in their compared sequences ? (please don't laugh at my question :-( )

 

[jim mcnamara]

For plants and animals it usually is:
1. similarity of reproductive organs (flowers, ovaries, etc..)
2. similarity of DNA sequences of course - this is called cladistics
3. Specific conservative phenotypic values (visible traits) - like mammalian teeth or the structure of the pelvis. This is used with non-living species - fossils.

#2 is the gold standard, but until we have that for every existing species we go with number 1, and secondarily things like #3.