On the Origin of "Species"

Don't blame me, blame this guy
http://www.icr.org/index.php?module=art ... iew&ID=338

I found the distinguishing characteristics of cladism to be of the most interest, because when thinking about the relation of species to each other, within the genus, I usually also think of the ancestral forms also as species.
When I relate the present forms to each other, then "think back" to where they could have come from, the kind of ancestral angelfish long ago, and that is also thought of as a "species", the conceptual difficulties are greater than if the ancestral form is thought of as a part of the clade, with possible inter-twining relations amongst the various groups within the clade. And by giving titles to these groups it is much easier to picture.

As an example, when describing my family, if all are just called "family member 'Jane' " or "family member 'Chris' ", things become more complex in understanding the relationship.

If I referred to "Grandfather Chris" , even a person with a small knowlege of my family tree might know I referred to my mother's father, he would have some approximation of the age or date of birth i.e. grand father is not one of the babies. He would have information of the "line" we are talking about. It would be clear we were not talking about a 3rd cousin to myself. If the person knew my paternal grandfather's name, then he could also deduce that Chris is my maternal grandfather.

Just realized the useful ideas cladism presents.
Last edited by rag on Sun Jan 08, 2006 1:45 am, edited 1 time in total.

re: On the Origin of "Species"

neatly disposed of anyway and making sense too, from the perspective of his era.
I would say that there is a reality despite the many distorted views we see thru the various methods.
the thing is Darwin avoided describing that reality , but left a gaping hole in our ability to communicate effectively about what he's talking about. Left the object ( not the subject) of his study undefined.
OK, simplified, as "things change, and for a reason", we can buy the Darwin stuff wholesale.
But we want much more than that now. We want to know relationships concerning this group of angelfish.

re: On the Origin of "Species"

Dave might want to bring up again his post on the Heroine family (High Bodied Cichlids), related to this subject.

Don't know if anyone has bothered to find out which of the species in the group was first, but specialization requires a relativey long evolution.

Looking at the group, It would seem sensible to me that the more specialized genera, such as Symphysodon and Pterophyllum sprang out of what I would think are more primitive genera, such as Heros and Mesonauta.

You can actually find Pterophyllum and Mesonauta in a same creek, the former hanging out near the river banks amongst the overhanging roots, branches and reeds, the latter, feeling tranquil in more open and shallow water.

Just some thoughts....

God listens. He may not always give you everything you want, when you want it; but he always gives you what you really need, when you need it most!

re: On the Origin of "Species"

Ed, I
I was wondering if there was any sense in looking at things from a viewpoint of more refined vs. more crude features on the fish, supposing that the more refined features such as it seems altum have would be a later or further development than a festivum-type fish.
Izeni put Pterophyllum as the base group in some tree of the heroines ( will find that article) though from the fin development and body look, angels are more specialized than discus.

re: On the Origin of "Species"

It looks very likely that angels and such as Heros, Mesonauta (look at the similarity of festivums esepecially to leopoldi) and maybe Uaru would come from a common ancestor.
That would take some study to determine, but must be readily possible.

The discus look just as specialised to me as the angels, but Dave might be right.

If we evolved from very ape like creatures in a million years or so, then I'd expect a fish with a breeding cycle of 12 months to radiate other species in just a few thousand years at most once new territorial or environmental possibilities opened up.

Someone has probably developed a formula for that...


re: On the Origin of "Species"

This is about Izeni Farias and the reference to the pterophyllum genus being the basal genus is in here.

http://golab.unl.edu/publications/Faria ... s_JME.html

"The monophyly of heroines was well supported by the 16S data and three major clades were found: (1) Symphysodon (Hoplarchus + Hypselecara); (2) Uaru, Heros and Mesonauta ; and (3)`Cichlasoma', Petenia, Archocentrus and Caquetaia. The relationship of taxa within and among these clades, however, was not well defined. Pterophyllum was identified in the ME and MP trees as the basal genus of the heroine group (Fig. 2 and 3)."

Re: re: On the Origin of "Species"

Alec wrote:Too true Dave.
One thing I'm often struck by is the relative speed of evolution.
Look at this article about cats.

That's the sort of study we need with angels.

while I don't think they call this a new species because of the adaptation , at least one definition of species would require both the old and new groups to be able to share the same evironment, and by that definition the "old style" and the "new PBC-friendly style" killies would be separate species.

http://www.washingtonpost.com/wp-dyn/co ... 00650.html

re: On the Origin of "Species"

Something I came across today.
http://www.nytimes.com/2006/02/21/scien ... ref=slogin

Interesting viewpoint of the time needed for certain new specieas to evolve.

IMO they are still too high by a significant factor. Would have thought hundreds should be enough, rather than thousands.
Also they don't just pop out overnight, so there has to be a progression.
I would have guessed a graph of a fish species evolving would show a very high rate of change in the beginning, slowing down as the fish adapt more.


re: On the Origin of "Species"

a little bit of synchronicity , Alec.
Yesterday while scoping out the skeptic forum ( the article mentions sceptics a few times) I noticed just the thing the article mentions a debate about.
A bird, I think it is a black cap something ?? , that lives in Europe, and winters in the south, has a population that has some go to one southerly winter resort, the other half to another resort for the winter. Upon return, they only mate with those that spent the winter in the same resort as themselves.
This is showing speciation independent of geographical separation (during the mating time).
the skeptic forum is a great place for finding diverse subjects under argument - very eloquent yet brief arguments.

one such interesting bit of info was on stickleback evolution, as they lose the armour as they move into fresh water.
Other subjects include examining the way physical complexity can come popping out due to genetics in a surprising way, trashing argument from anti-evolutionists.
Unfortunately ( or interestingly ) you may have to wade through pro-and-con Superior Being / Intelligent Design arguments, but they are even more fun as they are so crisply handled.
Maybe the brains are weightier on the sceptic side, as it is home base, but you can just search any subject and see such talent and info here.

re: On the Origin of "Species"

With genetic lines are too many questions now. Some ichtyologists are theorizing, that for determine of new species is importantly only detailed analys of their genetic fund DNA and conversely are ichtyologists, which assert, that analys of DNA cann´t rule for destine of new specie . If I can think ( only as lover and breeder any groups of freshwater fishes), that serious detailed analys of DNA is base element in orient now.

And about evolution of cichlids. If I take their first started place - it was Gondwana continent, where we searching their mother´s cradle, it was before more milions ages (yet before it was living in sea remote ancestor of ).
After it , how was break off continents from Gondwana to south America and Africa, was break off that remote ancestor to the lines of specific species. Through it too much species of cichlids have same form of their body (Apistogramma - Pelvicachromis, Cichlasoma /old genus/ - Haplochromis /old genus/, etc..). Here I can surmising, that remote ancestor was in his body similar as they.

Discus and scalars have different building of their bodies. I´m afford judge from it, that this fishes have young genetic fund, which is making yet now. I think, that they are evolve constantly yet now.

You know that case about one lake in Africa, where for last 100 years result from any few species of cichlids more species new?

Amazonian basin are too big place, where are living too much fishes, which we not know yet. Who know, what we are looking of Pterophyllum species in future time? On too much white places in map are yet write "hic sunt leones" now.
Breathing never coming from fashion!