Breeding Hints and Tips
The Real Value of a Hybrid
Written by Thursday, 07 December 2000 01:00
A short introduction by the Author:
My name is Simona Santini, 31, and I am a biologist, a fish keeper and a scuba diver. Every thing in my life, as you may see, is related to fish; to study, watch and breed them. I live in Pisa, Italy and am currently doing some research at the University. My wildest dream is to scuba dive in Lake Tanganyika, but this is almost impossible for the time being. The cichlids I am keeping at the moment are: Cyphotilapia frontosa "Kasanga", Julidochromis regani "Kipili", Tropheus sp. black "Ikola", Tropheus sp. red "Chilanga", Eretmodus cyanostictus "Zambia", Cyprichromis sp. Jumbo "Kitumba".
I wrote this comment on fish hybrids just to explain that the evolution is probably the most interesting subject related to fish and that people thinking of "improving" species are, at least, presumptuous....
The title may seem odd: “And now they’re trying to convince us that hybrids have a (real) value? We’ve been pestered for months when trying to sell/trade a fish at the annual auction (Is it a “pure breed” ? Are you sure it’s not a crossbreed between the Tanzania variety and the one from Zambia?!?!)”. Take it easy it’s all perfectly clear and that’s why I’ve put the term hybrid among “quotes”; I need it to make my opinion more clear. Hybrids, in any tank, have to be avoided, period! They have no value at all and any serious cichlid keeper should stay away from them. And to clarify things further here comes the reasoning: In the past (by the way, not that far ago!) the concept of “species” had been defined relying on the ability of specimens of opposite sexes to spawn giving birth to fertile fry. They used to say: “if their offspring is infertile then the parents should come from different species”. But what happens if they manage to breed? I keep in my tank the result of what I thought to be a “normal” spawning between a male and a female Black Altolamprologus calvus. Well … spawning took place in a community tank hosting, among others, five Neolamprologus caudopunctatus. The fry were looking like A. calvus, but upon their growth they started to look like N.caudopunctatus, or better, something in between: the shape was that of N. caudopunctatus, but the mouth looked like A.calvus, the colours looked like A. calvus but the fins like N.caudopunctatus. Till now I do not know how it happened since the male A. calvus was fertile and really “active” during that spawning. What probably happened was that a male N. caudopunctatus decided, while the spawning was still taking place, to “spray” a bit of its own sperm and unfortunately he was capable of wasting an otherwise perfect brood. Then what would you answer to the question "do A. calvus and N. caudopunctatus belong to the same species"? If - as I DO hope - your opinion is "NO", why the hell did they succeed in breeding? The old definition of “species” doesn’t fit any longer; chances are that the fry will be infertile and - since I did not dispose of them - that’s my last hope. If there’s a thing I do not need is fry from those fishes, period!
But the main question is still there: How is it possible for two species which are so profoundly different to crossbreed? The answer has to be related to the fact that those two species of cichlid are, so to speak, “young”. Lake Tanganyika, the environment where those two species came from, is also – from a geological point of view – young, being the result of earth’s surface movements about 12 millions years ago. Consider that the human species became significantly different from “monkeys” about two million years ago. However, most mammals started to follow different evolution paths between 65 and 10 millions year ago. Then the lake is young and species populating it are even younger. Two really "young" species even though they are different, still they have only a few genetic differences. Genomes are, still, quite similar in the cells of the two animals. This results in the chance of interbreeding. The fact that two different species can’t interbreed is because of a lot of tiny, slight, insignificant differences hidden in the genomes of two species living “close” in the wild. There is a point when those tiny, slight, insignificant differences begin to be “too much” to allow milt of male “A species” being compatible with eggs of female “B species”. At this point the two species will be considered different by humans. In reality, the two species started to “differentiate” from each other long before those tiny, slight, insignificant differences started to add up. Ichthyologists and genetists tend to consider “different species” some species that only differ in color. Just a few years ago there were only Tropheus duboisi and T. moori, while right now there are, at least, six different species. We are also aware of the fact that in the Rift Valley Lakes there are still species which are undergoing their process TO BECOME DIFFERENT. Being that young they haven’t been still able to fix all their own “characteristics”; they simply haven’t had the time they need to finish the process. Any kind of uncontrolled crossbreeding regardless of whether it has been intentional or accidental (mostly in a “small” environment such as a tank) is simply a step back in the evolution path which for millions of years selects and defines separate species. It needs centuries of tiny, slight, insignificant differences to differentiate two species naturally. On the other hand, it only takes an ignorant fish keeper to turn back the clock and God only knows how much …
Crossbreeding and producing hybrids is an unlucky event which every aquarium keeper involved in spawning in his tanks had had the opportunity to look at, at least once in his life. The main point is not to crossbreed on purpose just in order to “produce” something new at all cost. Generally speaking, those fishes are ugly (from an aesthetic point of view) and furthermore they are "monuments" from a different time point in the course of evolution. There’s no scientific interest in producing hybrids - this should be clear to all of us. We all know that it is possible to get hybrids so there is nothing new to discover by producing those unfortunate creatures. There is no way to describe anything (neither phylogenetically nor taxonomically) on these fishes. There’s no use in trying to crossbreed cichlids in our own tanks to see if it works. This is Goofy’s science. Evolution links among the different species are studied by means of an in depth analysis of data, repeated measurements of their morphological characteristics and study their genetic sequences.
However, things are far more serious (worse I would say) if the aim of crossbreeding (mixing eggs and milt of different species) is commercial. I would just refer to the Red Blood Parrot (possibly the result of breeding Amphilophus labiatus and Heros severus). As in this case, the result will be the distribution of something that could never exist in the wild.
This is the main point, and “crossbreeding addicts” seem not to get it right. Hybrids appear in a tank since a tank, despite all our efforts, is an unnatural environment for our fish which simply try to do their best. No matter how huge the tank may be it will always be very little compared to the space they would have in their natural environment. Crossbreeding is the result of living in an overcrowded environment and would never happen in the wild among the very same two species. Each one would have many more opportunities to meet a specimen of the opposite sex but SAME species instead of one of a DIFFERENT species. It’s a huge mistake to believe that if Mother Nature (who is that after all ?) hasn’t set up “genetic blocks ” to avoid crossbreeding then we’re allowed to crossbreed them. Those bringing up these arguments should better spend their time in observing nature and studying genetics in depth while at the same time examine the ethologic parameters of their actions rather than pursuing easy money and/or business needs.
As a suggestion to avoid this mistake as far as this is possible : closely related species are better kept in separate tanks. If this is not possible never keep a single specimen mixed in a group of members of a different species. Sooner or later the “single” specimen will be forced to spawn with a different species. Colour morphs and/or geographical varieties have to be kept separated, too. Keeping them in the same tank could result in crossbreeding. This in turn will result in further distributing species which are to become totally different than they should. This attitude will reduce the biodiversity of the species on this planet considerably - which is already at great risk for many reasons.
Despite all your efforts sometimes it may still happen. This has been the case for my “calvauds”, but once is more than enough! I haven’t “advertised” those fishes and neither “distributed” them and I DO hope every clever aquarium keeper will do the same. The aim of this article is to convince everybody that hybrids are “bad” culture, as further away from nature and REAL science as it can be.
You may contact the Author by This e-mail address is being protected from spambots, you need JavaScript enabled to view it
| < Prev | Next > |
|---|