It is currently Sun Sep 24, 2017 7:59 am
 

 




Post new topic Reply to topic  [ 24 posts ]  Go to page Previous  1, 2
Author Message
PostPosted: Mon Oct 25, 2010 4:41 pm 
Offline
Administrator
User avatar

Joined: Sat Sep 17, 2005 3:21 am
Posts: 4232
Location: Salt Lake City, Utah
Heiko brings forth a very important note.
To have hobbyists provide fin samples from fish they have most likely acquired at an LFS, or at best, from a wholesale/importer, does not provide any degree of reliability as to the source of their specimens.
There are some populations of RNa (Rio Negro Altum-Scalare) from the Upper Rio Negro that are virtually identical to Orinoco Altum. Even experienced hobbyists (including myself) can have a hard time when encountering some of these populations.
Fishermen are not avid to reveal exact locations of their catch and sometimes intentionally mislead the exporter or middleman (those who buy from the fishermen and sell to the exporter).
We can have Inirida Altum (most common) sold as Atabapo or Ventuari Altum, or we can have a so called Pterophyllum altum (actually Rio Negro Altum-Scalare...considered P. scalare) imported from Brazil. Not saying that Colombians or Venezuelans cannot sell true P.altum to a Brazilian Exporter. Years back it was frequent for fishermen to trade P. altum for wild discus at San Carlos de Rio Negro.
The only way to obtain fin samples from reliably sourced wild fish is to count on multiple parties willing to do a responsible part for the benefit of science in such a project. This is not easy, but possible. It's a matter of knowing all the right people and asking them to join in the effort.
I would like to thank Heiko for this important observation.
Regards
Ed

_________________
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!
E.R.


Top
 Profile  
 
PostPosted: Wed Oct 27, 2010 12:43 pm 
Offline

Joined: Fri Jan 29, 2010 9:57 am
Posts: 37
Location: San Jose,CA,USA
naturally there is a caveat on samples from hobbyists. but if there exists a palpable variation in DNA between altums and scalares then you would expect to see this variation, provided that in the samples submitted there are indeed altums (we expect a lot of scalares). if everyone submits all scalares then we probably wont see anything significant save for geographical population differences (but to find this you will need to test a lot of primers).


Top
 Profile  
 
PostPosted: Wed Oct 27, 2010 2:20 pm 
Offline
Administrator
User avatar

Joined: Sat Sep 17, 2005 3:21 am
Posts: 4232
Location: Salt Lake City, Utah
Perfectly undertsand your point of view, but many hobbyists who think they own P. altum actually own RNa P. scalare. Several years ago there were some large importations out of Brazil of fish that look very, very much like Orinoco Altum. Still, your method is the base to resolve what we are all interested in.
Ed

_________________
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!
E.R.


Top
 Profile  
 
PostPosted: Wed Oct 27, 2010 6:23 pm 
Offline
Administrator
User avatar

Joined: Sat Sep 17, 2005 3:21 am
Posts: 4232
Location: Salt Lake City, Utah
Also L204, I can see you're on a level that allows you to better understand the in-lab side of the issue than I can. But on the sample collection side, for it to be really meaningful, requires good logistics, multiple teams working along the geographical distribution locations and above all, good will and trust among the parties, starting from the fellas that throw the seines in the Orinoco and Negro collection spots and ending at either the exporter or the willingful and responsible importer who will for once, put his spirit of collaboration before his ambition to fatten his pocket.
Or of course, a well funded collector who can just go and get the samples him or herself with little need of a team until it's labwork time.
Ed

_________________
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!
E.R.


Top
 Profile  
 
PostPosted: Wed Oct 27, 2010 7:28 pm 
Offline

Joined: Fri Dec 24, 2004 10:39 pm
Posts: 2955
Location: Toronto Canada
L204EmperorFlash wrote:
naturally there is a caveat on samples from hobbyists. but if there exists a palpable variation in DNA between altums and scalares then you would expect to see this variation, provided that in the samples submitted there are indeed altums (we expect a lot of scalares). if everyone submits all scalares then we probably wont see anything significant save for geographical population differences (but to find this you will need to test a lot of primers).

Hi EmperorFlash
I look at a test like this from several views.

1/ How does it compare to other tests specifically regarding exactly the kind of sampling that we will have.

2/ How does our method compare to the actual method of sampling from the top pros ?

3/ How does ours compare ( eventually) in sample size ?

In all three views it's a good test...and later additions to the samples can add more clarity as it's not something that is "finished" per se.


Top
 Profile  
 
PostPosted: Wed Oct 27, 2010 10:34 pm 
Offline
Administrator
User avatar

Joined: Sat Sep 17, 2005 3:21 am
Posts: 4232
Location: Salt Lake City, Utah
Kill a thread? Kind of. Take care.

Ed

_________________
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!
E.R.


Top
 Profile  
 
PostPosted: Wed Oct 27, 2010 10:55 pm 
Offline

Joined: Fri Dec 24, 2004 10:39 pm
Posts: 2955
Location: Toronto Canada
L204EmperorFlash wrote:
naturally there is a caveat on samples from hobbyists. but if there exists a palpable variation in DNA between altums and scalares then you would expect to see this variation, provided that in the samples submitted there are indeed altums (we expect a lot of scalares). if everyone submits all scalares then we probably wont see anything significant save for geographical population differences (but to find this you will need to test a lot of primers).
This is one approach that I see done. Just test and see. We might not have firm locations, so consider that a fact of life, and then use tentative locations or forget about locations entirely for now.

That's still better than studiously avoiding the Orinoco when talking about P altum or about anything else, in relation to P. altum.

My prediction would be that every single sample we sent at first would be of Orinoco origin, somewhere. thus right off the bat, we have a superior position than was enjoyed in previous works. We be first to get to dial in "altum", in this way.

They would not be naive picks from store tanks, after all. It would be our fish.

I have one set suspected to be RN and one set Orinoco. Some batches have been identified by importer as to "Puertoayacucho", "inirida", "Sipapo" or suchlike, if they have that info.

Regardless, all those labeled that specifically are very very likely to be Orinoco, I think.

Most of all, we're free to sort them morphologically into categories that we choose.

If we all agree it's a very altumish altum, then it is. If there's doubt, as happens even with one or two fish in the group, where they may not display every sign, then that individual fish that does not outwardly display all necessary traits, would not be said to fit the phenome of altumish altum.

For whatever reason, be it parasites or poor eating or genetic , if the fish has the wrong shape, then it's not fitting the phenome.

In essence I would try to obviate error due to overprecision in interpretation or assumption of phylogenic or taxonomic relationship before we start and well before knowledge is gained.

Looking to the morphometric mapping landmarks used, from the angelfish photo in the recent study, it seems to be that the most information about variance is gained from the "face", as seems natural enough.

Eyes - diameter and placement, gill cover position, mouth and jaw shape and length, and snout indentation. Caudal peduncle area too.

My view is that if it is being said that fish from the Rio Negro are found to be scalare, but look so much like P altum as to be indistinguishable to the exporter, importer, and us ( yet have scalare DNA, not altum DNA ), then it might be that they are seeing that particular gene's history, not the fish's ancestry or relationships.

Here's the catch: I would accept as true that certain individual traits of some scalare, or altum /scalare hybrid, could come together in some scalare individuals or groups that are in range of altum number or quantity i.e a fish might show scale count or fin ray count in the altum range, with snout indentation appearance, etc, enough to qualify by older textbook style meristics as P altum if you were working blinded, could not get to see the actual fish, and only got the numbers... yet the fish would definitely fail the "eyeball test". Decently developed "Eyeballing" skill, is, after all, an excellent curve fitter.

This fish would not look like the most altum of fish in all respects, or it probably WOULD show hybridization in some genetic test.


Last edited by rag on Mon Nov 15, 2010 4:56 pm, edited 1 time in total.

Top
 Profile  
 
PostPosted: Mon Nov 15, 2010 3:22 pm 
Offline

Joined: Fri Jan 29, 2010 9:57 am
Posts: 37
Location: San Jose,CA,USA
hi rag and puertoayucho,

ive been busy lately with work ill get back to you on your questions. that is i need to do a review of literature on the current pcr techniques since the last time i did RAPD was during the late 90s.

best, L204EmperorFlash


Top
 Profile  
 
PostPosted: Fri Mar 04, 2011 7:36 pm 
Offline

Joined: Fri Jan 29, 2010 9:57 am
Posts: 37
Location: San Jose,CA,USA
rag here is a paper that summarizes the techniques:

http://www.springerlink.com/content/r21 ... ltext.html


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 24 posts ]  Go to page Previous  1, 2


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to:  
cron
Powered by phpBB® Forum Software © phpBB Group

 

 
 

Species Identification Guide


Domestic Angelfish Genetics


Angelfish Chronicles


Members Galleries


 
Contact: Forum Administration
E-mail: info@finarama.com
Finarama.com
Dedicated to further understanding the Genus Pterophyllum