DB junkie;2355601; said:
There are many natural barriers that prevent fish from migrating from one river to another. Its not just distance.
Black rays, hybrdization, and locations. P14, BD, leos, henleii
- Thread starter michael
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There are many natural barriers that prevent fish from migrating from one river to another. Its not just distance.
x2. I think they are lots of stingrays that probly migrate just like other animals. You can't tell me that Leo are locked down in their part of the river, P14s in another and Henlei in another. I am sure these have crossed in the wild.DB junkie;2355927; said:
There are many fish species whos whole population is isolated to just one or two sections of a small creek.
Obviously this is not the case with rays but things like water falls and rapids sure make it hard for rays to get out of certain rivers. But like I said in the relative recent past, say just say ten thousand years ago, its possible these rivers could have been on a different course and ran together for a short (geological time) while allowing the fish to interbreed.
Obviously this is not the case with rays but things like water falls and rapids sure make it hard for rays to get out of certain rivers. But like I said in the relative recent past, say just say ten thousand years ago, its possible these rivers could have been on a different course and ran together for a short (geological time) while allowing the fish to interbreed.
I also wanted to add that both the Xingu and Tocantins end in miles and miles of rushing rapids and water falls which is not that common in the amazon. A ray CAN NOT travel through that. I think its more then a coincidence (sp? lol) that two very unique rays are from such isolated rivers.
Check out these maps.. seasonal flooding makes migration through the flooded forest very possible, even if the rivers have rapids near their outflow areas..
First map is the area that black rays come from.. helps put it in perspective. Remember, Brazil is the largest country in the world, these rivers are far apart.
Leos from Xingu
Henlei from Tocantins
P14 from Tapajos
Second Map shows the flooded forests from a satellite image.. the blue areas are completed submersed in water. The darker the blue, the deeper the water.. It is the area near Manaus, but most all of those 3 river systems will become flooded depending on the area.
Also.. a dam was built in the Tocantins that apparently has isolated a very large group of Henlei, to the point where they have become a nuisance to local fisherman. Apparently fisherman are reporting raised levels of populations behind the dam.
One thing to ponder and consider is the thought of a single male species (say Leopldi for example) is to cross a very narrow bridge of flooded areas, only to become isolated in a completely new tributary system during the next dry season. Naturally, it will attempt to breed with other species if it can find no company of it's own.. So it makes me wonder if a single rogue Male Leopoldi could infect an ENTIRE river systems potamotrygon population by pregnating 3-4 females in a single sseason.. and then effects the colour pattern of that species for many generatinos to come... and to think, this scenario could happen EVERY flooded season, more than we think..
First map is the area that black rays come from.. helps put it in perspective. Remember, Brazil is the largest country in the world, these rivers are far apart.
Leos from Xingu
Henlei from Tocantins
P14 from Tapajos
Second Map shows the flooded forests from a satellite image.. the blue areas are completed submersed in water. The darker the blue, the deeper the water.. It is the area near Manaus, but most all of those 3 river systems will become flooded depending on the area.
Also.. a dam was built in the Tocantins that apparently has isolated a very large group of Henlei, to the point where they have become a nuisance to local fisherman. Apparently fisherman are reporting raised levels of populations behind the dam.
One thing to ponder and consider is the thought of a single male species (say Leopldi for example) is to cross a very narrow bridge of flooded areas, only to become isolated in a completely new tributary system during the next dry season. Naturally, it will attempt to breed with other species if it can find no company of it's own.. So it makes me wonder if a single rogue Male Leopoldi could infect an ENTIRE river systems potamotrygon population by pregnating 3-4 females in a single sseason.. and then effects the colour pattern of that species for many generatinos to come... and to think, this scenario could happen EVERY flooded season, more than we think..
