[pranjalv123]

Don't all time-dependent processes result in dependency graphs? The only way you could have a circular dependency is if one organism was a parent of one of their ancestors, which is obviously impossible*

*actually, it's not impossible, since you could have a child transmit DNA horizontally to its parent, but this would in reality happen over a sufficiently short timescale that you wouldn't see it on a phylogenetic tree.

[DoreenMichele]

No clue what you are talking about, but, technically, human women become chimeras when they reproduce because the baby leaves behind some of its genetic material. Human children transmit their DNA to their mothers in utero to some degree.

[TeMPOraL]

Couldn't lifecycles of some parasites be considered circular dependencies?