4
$\begingroup$

Definition of Convergent evolution - from Wikipedia > Convergent Evolution

Convergent evolution is the independent evolution of similar features in species of different lineages. Convergent evolution creates analogous structures that have similar form or function, but that were not present in the last common ancestor of those groups.

Examples

-- Lactase --

Humans have evolved the ability to digest lactose at adult age twice; once in Europe and once in Africa. Different mutations are involved in European lineage and in African lineages.

Source: Tishkoff et al. (2007)

-- White fur --

Beach mice and mammoths have both evolved white fur independently. The same mutation is involved in both lineages.

Source: Römpler (2006)

Question

Is there a term to differentiate convergent evolution that involves the same mutation in different lineages from convergent evolution that involves different mutations in different lineages?

$\endgroup$
  • $\begingroup$ This is really a question of semantics, as there are not universally accepted definitions of these terms. The first example (lactase) is by the given Wikipedia definition not really "convergent evolution" since it states that it occurs "in species of different lineages" - not within one or very closely related species. This is a mutation that occurred twice in lineages of one species, and might be better termed genetic parallelism. I am not sure it is useful to speak in vague macroscopic terms like "convergent evolution" when discussing subtleties at a genetic or molecular level. $\endgroup$ – Harry Vervet Feb 25 '16 at 22:42
  • 1
    $\begingroup$ I have to say I really enjoyed this question, it was a new thought for me and it's great when biology SE gets to poke around in these sorts of very academic areas! Enjoyed reading for it and scouring literature for an answer - nice one @remi.b thanks for posting such a good question! $\endgroup$ – rg255 Feb 26 '16 at 16:24
2
$\begingroup$

As you already know convergent evolution is when two separate lineages evolve the same (or similar) trait, and this is generally assumed to be a result of similar selection. For example, if flying helps both birds and bats catch insects to eat, then convergent evolution of flight is somewhat unsurprising. Other examples include those of mimicry where the convergence on a common colour patterning reduces predation rates.

The wikipedia page on convergent evolution does a pretty good job of explaining the subtle difference between parallel and convergent with its illustration. In convergent evolution, two lineages have dissimilar starting points and arrive independently at similar end points. In parallel evolution, two lineages have similar start points and arrive independently at similar end points.

"...a convergent change at an amino acid site refers to changes from different ancestral amino acids to the same descendant amino acid along independent evolutionary lineages ... It is distinguished from a parallel change, in which amino acid changes along independent lineages have occurred from the same ancestral amino acid (see fig. 1A for examples). Both convergent and parallel evolution, if verified, suggest adaptive evolution."

This, and other sources (page 113), suggests that convergent and parallel evolution/change/mutation are relevant terms. In your context you are looking for a term to differentiate two cases.

  • Case 1: convergent evolution of a trait, by different mutations; either different nucleotides at the same site, or mutations at different sites. This is seen in your lactase example.

  • Case 2: convergent evolution of a trait, by the same mutations; the same nucleotide changes at the same site(s). This is seen in your white fur example.

A key point is that your are looking at convergence at two different levels, phenotypic and molecular. In both cases you have convergent evolution at the phenotypic trait level. The cases differ at the molecular level where you have convergent and non-convergent mutation respectively. I have found one term being used in this paper.

"In some cases it has been shown that different loci are involved in phenotypic convergence (e.g. Refs [8,25,26]), demonstrating that similar phenotypes can be reached through alterations of distinct enzymes. However, other studies have traced phenotypic convergence to modifications of homologous genes (e.g. Refs [3,5,6,26,27]); in this paper such phenomena will be further referred to as convergent recruitment (Glossary)."

I think the term you are looking you are looking for would be convergent recruitment to describe case 2, and some form of antonym* for case 1, perhaps you could say non-convergent recruitment. However, non-convergent could make it sound like no convergence is occurring so I'm not a fan and you should be careful in any papers to clarify. I'd say something like:

"Phenotypic convergence by the recruitment of different genes and/or mutations is herein referred to as non-convergent recruitment, in this case convergent evolution is occurring but through non-homologous changes at the molecular level."

You would then have to be consistent in your writing, talking about the phenotypic level as (non-)convergent evolution and molecular level as (non-)convergent recruitment. E.g.

"The convergent evolution of flight occurred as a result of non-convergent recruitment."


* I couldn't find an established antonym term, and as I suggest in the post, I don't think non-convergent recruitment is a perfect antonym, we could discuss it in chat or the comments to try to come up with some new terminology. Perhaps "non-homologous convergent evolution" or "non-genetic convergence" would work? In this paper they simply refer to it as "convergence through different mutations".

$\endgroup$
3
$\begingroup$

I'm not aware of a specific term for this. In the places I can find the concept discussed in the literature (here and here), the authors simply describe the pattern as "the same [...] mutation in two lineages" and "parallel mutation in two lineages".

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.