What is the def. of extinct, and how do hybridization work in phylogeny

[Guest Anton Juhl]

Greetings.

I was just having a discussion with my brother about, whatever it makes sense to say, that the Neanderthals are extinct.

So I was hoping that someone could point me to the definition of extinct  used in biology.

I also hope that someone could explain how or point me to an article about how hybridization is handled in phylogeny?

Sincerely Anton

[brachiosteve 14]

Dear Anton.

Great questions. I have been writing quite a long answer which may also be worth a wider readership given such interesting and relevant points, so pleaser bear with me, though anyone else is welcome to join in the response.

Steve

[brachiosteve 14]

Dear Anton. It has been a long time and I see that no-one has responded, so I'll give it a shot.

‘Extinct’ in biology means to no longer exist as a living representative. It could be a species hypothesis or other taxon hypothesis. So, dinosaurs still exist because a branch (aves) still lives. Pterosaurs are extinct to the best of our knowledge (meaning that the fourth independent branch of flight ceased to exist). The dodo (as a species representative) is extinct. The Thylacine is classed as extinct, but if we find a living example, it will be removed from that list.

According to the IUCN Red list category, they uniquely use the term with some caveats. For example, extinct in the wild represents the fact that we have managed to preserve the example(s) by way of using zoos, insemination or similar artificial means that would otherwise mean it became extinct entirely.

If an organism is bread back, such as attempts have been made with the quagga for example, then it gets more complex.

Which leads to the other parts of the question.

As far as we know, Neanderthals/Neandertals (whether you refer to the species or subspecies https://en.wikipedia.org/wiki/Neanderthal), is extinct, though we have found that we (Homo sapiens sapiens) have reproduced with them, based on testing the DNA of many modern humans.

Rumours (by scientists too) exist that suggest the hobbit (Homo florensiensis) in parts of Indonesia still exist, but no convincing support has been brought to bear.

Regarding hybrids, it is a topic that particularly interests me and I spoke a little of this, regarding cladograms on the Facebook group. For example, the largest cat to have ever existed is the Liger, which is a male Lion/female tigress hybrid, (with that combination accounting for the growth from the female tigress) but most zoos do not support such cross breeding as it offers science little and creates genetic weaknesses. Hybrids have sometimes gone on to breed with standard species or even other hybrids, but this tends to push health boundaries. Almost all big cats can interbreed, including cross continent, e.g. jaguars with lions, tigers or leopards.

Did you know that in the history of the world, only one example of an African/Asian elephant has ever existed? Born in Chester zoo, England, Motty (male) was born on 11^th July 1978. He only survived a couple of weeks. See photo.

Phylogenetic trees do not represent such examples as it has little interest to science and is complex to represent on the cladograms or dendrograms in current use.

Another reason is the definition or interpretation of a species. A species is not something that actually exists. You can’t touch a species, you can only touch an individual organism. It is a concept or a hypothesis to demonstrate (and when attempted, always seems to fail or omit something at best). Like any other taxa which equally do not exist in reality.

Systematics is a better word replacement for taxonomy. The purpose of examining organisms is to systematise them. Taxonomy pre-supposes things and restricts its use.

I hope this answered your question(s).