Hi Christian, what do you mean by the difference between "true parallel evolution" and "parallelism"?

Pan and Gorilla after the split with Homo evolved in parallel e.g. knuckle-walking and iliac elongation, and possibly a number of other traits.

hello Christian,

Searching for true cases, you suggest that they are generally false....

What do you need to define "trus parallelism" ?

- same global morphology

- same function

- same structures modified to produce this morphology (which implies searching within a same clades !)...

- with similar modifications (at which point of details ? this might be limited at some point by the fact that you compare 2 different taxa)

Meeting all points, you might find some nice cases in fishes, for instance comparing South American and African catfish families that occupy similar habitat.

Best,

Olga.

Hi, Christian,

I think that a good example may be the fact of enucleated red blood cells in the lungless salamanders (Plethodontidae). This trait is independent of similar situation in mammals.

Regards,

Alexey

Hi, Christian, I think that a good example may be the fact of enucleated red blood cells in the lungless salamanders (Plethodontidae). This trait is independent of similar situation in mammals. Regards, Alexey

Dear Marc,

parallelism implies that the direction the evolution of a trait assumes is the same in two lineages, but the rate or degree of change differs.

Parallel evolution means that both the direction and the rate or degree are the same.

Best wishes,

Christian.

Late Volgian craspeditid ammonites are showing good example of parallel evolution for lineages evolving in three semi-isolated areas (see Article Khetoceras (Craspeditidae, ammonoidea)—A new genus from the ...

Similar examples of parallel evolution within the different basins are relatively common for latest Jurassic Boreal regions (i.e. Kimmeridgian - Volgian Dorsoplanitidae vs Virgatitidae, etc)

Hi Christian, "parallelism implies that the direction the evolution of a trait assumes is the same in two lineages, but the rate or degree of change differs. Parallel evolution means that both the direction and the rate or degree are the same."

I wonder whether one can find many cases where traits evolve in parallel at exactly the same rate or degree: does "true parallel evolution" exist?

I wrote a few papers on parallel evolutions (what you call "parallelisms"?) in ape & human evolution.

In the case of the great apes (hominids & pongids), Pan & Gorilla evolved knuckle-walking in parallel (the hominid LCA didn't have it), but Pan & Gorilla KWing are somewhat different ontogenetically & morphologically. Pongo evolved "fist-walking", not KWing, whereas humans (infants) & gibbons remained palm-walkers.

Iliac elongation evolved in Pan, Gorilla & Pongo in parallel, and partly in Hylobates, and was/remained absent in most fossil hominoids & Homo.

Hand & arm elongation occurred in hylobatids, Pongo & in a lesser degree in Pan, more than in Gorilla & Homo.

Dear Colleagues!

All cases of the true parallel evolution in the same taxon are the results of the parallelisms or convergence (no true boundary) based on the Osbourne's principle of latent homology. But we have many examples of convergence between taxa with initially different structures of the body: Gryllotalpidae and mole, Sphingidae and caliber, worm and lamprey, eyes of the octopus of mesoderm origin and eyes of vertebrates of ectoderm origin, etc. I specially gave examples between two very different groups of animals: Protostome and Deuterostome. This may indicate that the environment itself dictates the rules. However, it would be easier to answer your broad question if you had formulated your tasks specifically.

Thanks a lot for all your answers!

Hi all,

all above remarks are noteworthy. But a "good" example can be found with freshwater dolphins: Iniidae (Amazon river) versus Platanistidae (Indian rivers), see C.E. Page et N. Cooper. 2017. Morphological convergence in « river dolphin » skulls. PeerJ 5:e4090; DOI 10.7717/peerj.4090 and Steeman et al. (2009).

Some authors (e.g., Gould) restrict the use of "parallelism" to the cases where a similar morphology is evolved using the same genes/developmental pathways. They use a broader meaning for "convergence" when similar morphologies can be evolved using different genes/developmental pathways.

A well-documented example of convergence/parallelism (not sure whether we can know whether the similar morphologies were evolved using the same genes...) is the evolution of third molars with very high and long crowns in African suids. That happened independently in at least three clades of suids (probably more), presumably as herbivorous adaptations in response to environmental changes.

Thanks for your answers!

Since I am working with fossils, I am largely limited to morphological data.