Breeding care, instinct or learning process?

[cageman]

On the Dutch Dwarfcichlid forum there is an interesting discussion going.

Some say young Dwarfcichlids learn the broodcare from their parents.
Some say this is nonsense and broodcare is instinct, and thereby genetically determined. Fact is that fish who did not have broodcare can perform broodcare just as their parents would have done for them. Maybe even if there are some generations between them.

I wanted to know how some of the experienced breeders think about this theme.
Maybe someone knows of some researches on this subject.

 

[lab]

I don't think it has anything to do with learning either. I do think that there could be an effect on the longer term if eggs are artificially hatched continuously for many generations, but that would be an effect on the gene pool by artificial selection.

A friend of mine is performing a bachelor's project in biology on the University of Copenhagen on this subject. He is using convict cichlids in his experiment. There should be some results before the end of this year, if all goes well.

Lars

 

[ed seeley]

I'll be very interested to see the results of your friend's experiment.

I have always assumed there must be a learnt aspect to broodcare. That doesn't mean there aren't genetic aspects too. Complicated behaviours can be inherited but they are also often learnt by experiencing them too in vertebrates. Studies done on some birds that were fostered by brooder chickens tried to breed with other chickens, rather than their own species as they had imprinted on their foster parent (I can't remember the paper, but it was a classic study).
If mate recognition can be a learnt apsect why not brood care patterns too?

Brood care behaviours could be encouraged by genes coding for certain aspects of the behaviour, but may need to be triggered in life by having the experience themselves, or, as in some insects, they may have to be completely inherited as the offspring never meet their parents.

I have heard people who have experienced poor brood care in their fish that they knew had been raised artificially. I have not experienced this myself, but I don't think I have ever had an artificially raised cichlid AFAIK.

 

[Peter Lovett1]

I do not think brood care is a learned behavior but instinctive.

We forget that in the wild the survival rate of fry is very small less than 1% of any brood. In captivity the rate may be as high as 99%. I dont think anyone know how instincts are encoded into DNA but the coding most be very complex equally as complex as the instinct its self.

Brood care is a complex instinct. A female fish has to gauge the energy she puts into it. When to eat eggs when to eat or abandon fry. Even the smallest error in this coding will cause problems in a females ability to carry out brrod care.

When artificial raising of eggs and fry are used errors in the encoding make no deferents.

In the wild females with bad coding would not raise fry as well as other females and so her badly coded DNA would die out.

 

[cageman]

Thanks for the answers. I think about it the same way as you all.
Altough there migt be a little learning process in breeding care itself.

I do think parents get more experienced in the breeding care after a few nests. Mainly in things like finding food for the young or getting to know the possible predators.

@Lab: I'm also very interested in the research of your friend. If he finishes it, is there a possibility I can have a copy? When it is in English ofcource, my Danisch is a bit rusty lately:tongue:

 

[ProF_FR]

Hi,

I personnaly would said at first shot that there is the instinct but also a learning process. BUT i'm convinced its not really "learning" but closer to imitation .. the saw how mom cared about them and they reproduce such a behavior.

What is sure is that fry NEVER saw their parents during spawning and egg fertilization but they know how to do

ProF

 

[tjudy]

I think that the basics are instinct, because there are many cases when young fish are not raised in the presence of breeders and cannot therefore learn from them. Perfection is a matter of experience. IME many first or second spawns are unsuccessful, but the pair gets better in later broods.

 

[lab]

Lab: I'm also very interested in the research of your friend. If he finishes it, is there a possibility I can have a copy? When it is in English ofcource, my Danisch is a bit rusty lately:tongue:

He, he:biggrin: I really don't understand why there are not more people learning Danish. It would make things so much easier:wink:

I think there is a possibility that he will do an article in English, so let's see. Anyway I promise to give you guys a resume of the results. In my own interpretation off course:tongue:

 

[Nick S.]

Brood care

I think a lot has to do with the species and how long they have been linebred. If you take Angel fish for example the fancy ones have no idea or inkling how to look after their eggs, they eat them they knock them down, or they eat the wigglers or free swimmers. The instinct is there they just don't know how to look after them.

 

[Apistomaster]

I second Nick S on this.
Most Apistogramma are still pretty much intact as far as brood insticts go. I do think practice makes perfect.
But when fish like angels and domestic discus have been subjected to intensive breeding for innumerable generations in captivity their brood instincts can be nil to zero in many cases.

 

[Graham]

I'm curious as to why captive raised livestock would be prone to losing the brood-care instinct? For example, I have some A. trifasciata that are reportedly "about F-350" and the brood care instinct is alive and well. I seriously question even an F-1's ability to "know" they aren't in the wild if one caters to their physiological needs as a species.

I think it would have more to do with water parameters and overall environmental conditions than any loss of instinct - in other words: environment, not genetics. Wild fish are just as prone to eating eggs and being poor parents IME, maybe even moreso than the captive-raised stock I've bred. If I have a pair eating eggs, I'll wager 9 times out of 10 it's not them, it's "me".

You also have the argument of needing to give the mothers something to protect the brood from. Dithers go a long way in "forcing" brood care.

Take instinctive brood-care behavior in dogs for example. They are largely more domesticated than any fish other than possibly goldfish. They haven't lost their maternal instincts and most dogs are about as far removed from the wild as any animal on earth. A more complex beast without a doubt, but still full of instinct.

 

[ed seeley]

'Linebreeding' and 'Captive breeding' will effect the genetic diversity of the captive population. Founder Effect, caused by the small sample of fish taken into captivity from the wild, will mean that only a proportion of the genetic diversity of the wild population will be represented in captivity. Some genes, rare in the wild, may be present at high levels in the captive population whereas some genes will be lost. When these fish are bred (as only a percentage of those captured will be bred) more gentic diversity will be lost from the F1 generation. So even after one generation in captivity our population may well be significantly different, genetically, from the wild population. This loss of genetic diversity though may not effect the appaearance or behaviour of the captive population at all though!

There is the potential for 'good brood care' genes not being passed onto future generations in captivity by artificial rearing of those individuals who do not look after their young, but I am pretty sure that this is not happening. The reason for this is that a mutation at some point would have to have occured that gave this lack of brood care a genetic factor that could then be acted on by selection and be, or not be, passed on!
This could happen with a species (and the longer they are kept without needing genes for good brood care the longer there is potential for this to happen) but for the mutation to occur after only a few generations is extremely unlikely.

The simple explanation, IMHO, is that generally fish artificially reared are not good parents themselves because there is a learnt aspect to brood care. Fish that were raised by their parents use a combination of instinct and memory to be better at it the first time. This first brood is still a huge learning curve for the parent(s) and is often unsuccessful, but then, by the second of third brood, a combination of instinct (possibly/probably the major factor), memory from when they were raised and learnt behaviour from previous broods would lead to greater success. Fish certainly seem to get better at raising broods as they get older IME. I have a pair of P.suboccelatus 'Matadi' successfully raising a brood in a tank with 5 congo tetras, 2 wild angels and 10 corydoras. Their first brood didn't survive glowlight and cardinal tetras!!!

Anyone sitting there thinking, "Fish can't remember like that, certainly not from being a fry!" should look at Salmon. These fish have memory of the spawning grounds that they carry throughout their lives (probably them smell of them). Once they hatch, they drift downstream, but as adults they return to the same spawning area. Transplanted salmon fry/spawn re-intorduced from different rivers have returned to the place they were released, not the river they were spawned so that can't be a genetic factor because then they should reutrn to their genetic origin.
Why can't cichlids remember things from when they were fry too? As improbable as it may seem...

 

[lab]

Ed, I think you are discussing two separate issues. The parents' ability to defend their brood, which may very well be learned to some extent, and the parents ability not to eat their eggs/wrigglers. I really don't see how a behaviour like that can be learned. I don't think that trial and error could be involved in that. It just doesn't make sense. Have you ever thought about why all cichlids have brood care in some form? This suggests to me that there must be a very strong genetic foundation for this behaviour.
Apart from that there could be lots of explanations for parents to eat their eggs, like Graham suggested.
As long as there are no scientific results, all we can do is speculate. So let's wait and see

 

[ed seeley]

Ed, I think you are discussing two separate issues. The parents' ability to defend their brood, which may very well be learned to some extent, and the parents ability not to eat their eggs/wrigglers. I really don't see how a behaviour like that can be learned. I don't think that trial and error could be involved in that. It just doesn't make sense. Have you ever thought about why all cichlids have brood care in some form? This suggests to me that there must be a very strong genetic foundation for this behaviour.
Apart from that there could be lots of explanations for parents to eat their eggs, like Graham suggested.
As long as there are no scientific results, all we can do is speculate. So let's wait and see

I totally agree with almost all of this, and didn't contradict any of this in my post as far as I am aware, but I don't see that there are major differences between caring for eggs, wrigglers and fry. They are all part of the same thing and would increase fitness only if they were all effectively used by the fish. I said instinct is probably the major factor, but I was talking about the whole raising process, not just one bit. Obviously didn't make myself clear on that, sorry.

The topic of 'Brood instincts' and the amount of 'line breeding' came up, and to me that is the whole raising process, not just eating eggs or not. The title of the thread is "Breeding Care, instinct or learning process?".

The effects of captivity on the genetics of a population are wide reaching and I was discussing those with a view to the potential effect they may have on genes and possibly brood care genes too. Off topic maybe, but thought they may add something - maybe I was wrong!

I agree, at egg/wriggler stage there has to be instinct at work, which presumably will be a heritable factor, but then there will be a learnt aspect to the subsequent stages and maybe this one too. Please note though that there will be heritable aspects to learnt behaviour too. Some individuals will be 'better' at learning what to do!

As to the fact that there is brood care in all cichlids. There are a number of possible answers to the commonality of this. The first, and most probable, is that it evolved once in a founder species and all have inherited this. If something is inherited it must have a genetic factor that can be selected. I have never thought, or said, that all of brood care is learnt. I believe both learning and genes/instinct are responsible. Of course brood care has arisen independantly in a large number of fish species, they almost certainly didn't all arise from 1 brood caring ancestor, but brood care must have arisen independantly more than once. It may have in cichlids.

I don't think (but it is just my opinion) that you can breed fish with genes that 'make' them eat their eggs and it would be almost impossible to prove that fish had 'lost' genes for not eating their eggs. I think even captive bred angelfish posess the genes to raise broods, I don't know why they don't. It may have something to do with other selective pressures. Maybe actually to answer this question what needs to be done is a series of crossing experiments with wild angels to see how brood care is inherited, if at all. Or maybe captive bred eggs could be fostered by wild parents and see what happens when those babies bred. I would love to try this if only I had the space.

New parents often eat their first brood but then go on to make great parents? I have had fish eat first broods that were bigger than subsequent broods that they left in the same tank and conditions AFAIK. Maybe they 'learnt' (found may be a better word) that their eggs were safe in this territory??? Therefore they let their next batch develop.
Please note this is total hypothesis, but I don't think there's anything wrong with that - I'm not saying I know the answers and if it comes across like that I apologise. I'm merely adding my views/ideas to this debate.
I'm looking forward to the results of actual experiments too, but what's wrong with speculating until we have some results? As long as everyone realises this why not debate it?

 

[lab]

Nothing wrong with speculating. A great hobby of mine too I just meant that it would be nice with some experiments backing it up. I don't think we disagree on that.

Maybe not on so much else really. I might have been a little one eyed reading your opinion. I'm sorry if I came across a little harsh.

One thing I have to say is that I never had reason to conclude that new parents are worse parents at first than they are later on. I have read this so many times, but simply disagree with the conclusion. I believe more in the hypothesis that let environmental factors explain this. Or in monogamous species something may have gone wrong in the relation between the parents.

Oh, btw what does AFAIK mean? (English is not my native tongue)

 

[Graham]

AFAIK = As far as I know

Good discussion, folks!

 

[beleg]

My female A.agassizi which have been eating batch after batch has been caring for its last brood. I think adding a lot of Java fern and anubias that i have no where to put has made her feel more secure. The plants are not even rooted, they just float in the tank.

 

[ed seeley]

Nothing wrong with speculating. A great hobby of mine too I just meant that it would be nice with some experiments backing it up. I don't think we disagree on that.

Maybe not on so much else really. I might have been a little one eyed reading your opinion. I'm sorry if I came across a little harsh.

One thing I have to say is that I never had reason to conclude that new parents are worse parents at first than they are later on. I have read this so many times, but simply disagree with the conclusion. I believe more in the hypothesis that let environmental factors explain this. Or in monogamous species something may have gone wrong in the relation between the parents.

Oh, btw what does AFAIK mean? (English is not my native tongue)

I don't think we disagree much at all either lab.
Didn't come across that harsh, I just assumed I hadn't made things clear (again!)! :biggrin:

I've definitely noticed parents getting better with future broods for my dwarfs. But then maybe I did something different, who knows when it's not set up under controlled conditions!

I had a thought to the whole debate this morning while waiting for my class to file in. We are discussing this like there's a single unit of inheritance that codes for brood care (or some part of it). Of course it can't work like that. Dawkins, in the 'Selfish Gene' and 'Extended Phenotype' proposes that genes, or really sets of genes, may well code for behaviour like "If x, y or z happen do a." They will be giving the organism a set of simple directions, much like a computer program, that will build on each other to form seemingly complex behaviours from simple starts. (This, by the way, will all be programmed into the fishes brain as it develops during growth, well before the actual decision is made.)

The learning aspect may well just be "If you lost the brood doing x last time, do something else." This will lead to improvements in success one brood from another, but wouldn't pass on the fact to do something else first to the next generation.

The point I'm trying to make is that maybe a lack of recognition by the fish at some point in the brood care might trigger a gene complex and cause the brood to be eaten at any stage. Any, seemingly insignificant, trigger may cause it, not necessarily a particularly relevant one. This may be a part of the care the parent recieved when it was a fry, rather than an actual memory of the same stage when it was an egg!

Have I made that understandable?

 

[Graham]

I think we're trying to identify that bridge between instinct and memory-based learning - or at least make it more cut and dry, when I don't think we can. It may be a part of each, though I think "fish memories" or cognitive learning is likely quite rudimentary at best when it comes to something complex like brood care. Training your fish to learn to come to the top of the tank when you add food is one thing... Learning how to take care of babies - I'm not so sure!

 

[nightowl1350]

I think it is both instinct and learned.

I raised some rams from eggs as the male kept eating the wigglers. He would chase the female away from the eggs, but I know the female was parent raised.

A pair from the spawn I raised went on to parent raise in a well planted tank for someone else.

I have had this happen with angels as well. Sometimes it was both of the angels I raised other times they were pair with a non sibling, but we didn't know if the other angel was parent raised or not.