designer fish and genetics discussion

I think there are some misperceptions about inbreeding here. Inbreeding is certain to occur in any finite population. If you're expansive with your definition of inbreeding it's impossible not to inbreed, since all individuals of a monophyletic species come from the same ancestral population. In some (probably a minority) situations inbreeding definitely does have benefits compared to outbreeding. A good example are two closely related populations of plants (this is from a real paper, I forget the species), one in the mountains where it is cool and dry and one in the valley where it is warmer with a longer growing season. Both are well adapted to their respective locations and climates. If there is interbreeding between the two, the resulting offspring is less fit in either location than the parents, so inbreeding within each population is reinforced. In animals, inbreeding has been noted in the cheetah, which is so inbred that (again, another actual experiment) one can take skin from any cheetah and successfully graft it onto any other cheetah without rejection. Their genomes show very low heterogeneity, if I recall correctly one of the lowest of all mammals. A hypothesis in this situation is that the majority of the deleterious alleles have already been eliminated from the population (fixed at 0). Granted, hunting by human beings probably hasn't helped the situation. Without inbreeding, sympatric speciation (speciation where the parent and new species are not separated geographically) would be difficult to impossible.

As for clownfish, seeing as how they do not widely disperse in the wild, I would not be surprised to find many small wild populations that show low heterogeneity. Remember we're talking about a group of species where often, due to sex changes, a lost parent is replaced by an offspring (e.g. if the male dies, one of the juvenile offspring will pair with the female, its mother). My point is that without knowing the heterogeneity of the wild clownfish populations where they collect their parent stock, it's impossible to know if their breeding methods significantly increase the rate of sib or parent mating from the wild. I also don't know of any connection between barring patterns and strongly deleterious alleles. As for "benefit of the species" I think that is beside the point, as captive clownfish are completely reproductively isolated from their wild counterparts. From an ecological standpoint they're as good as dead, especially in that unlike a cat or dog they're not going to go feral (god help us) and overrun the city streets :). Welfare of individuals is important, we are morally responsible for the well-being of our livestock, but if concern for the species as a whole is foremost then the possibility of fixation of deleterious alleles from inbreeding captives shouldn't be a large concern, it should be protecting wild populations from overharvesting. I also highly doubt that ORA is going to risk their all of their broodstock to inbreeding depression.
 
FutureInterest;127310 wrote: YES :).

Anyways it just boils down to you being against all types of selective breeding, which you are assuming they are using in their breeding program. It's your opinion and you are entitled to it. I respect your stance, I just happen to disagree. :)
Click to expand...

We will agree to disagree then, and I will sahke your hand the next time I see you. well said. I still think you are misunderstanding me. I am absolutely not against selective breeding, but I favor it in terms of improving vaibility, fecundity, or other "positive traits, not for negative traits which show no benefit to the species (or marginally the individual).
 
LockeOak;127333 wrote: I think there are some misperceptions about inbreeding here. Inbreeding is certain to occur in any finite population. If you're expansive with your definition of inbreeding it's impossible not to inbreed, since all individuals of a monophyletic species come from the same ancestral population. In some (probably a minority) situations inbreeding definitely does have benefits compared to outbreeding. A good example are two closely related populations of plants (this is from a real paper, I forget the species), one in the mountains where it is cool and dry and one in the valley where it is warmer with a longer growing season. Both are well adapted to their respective locations and climates. If there is interbreeding between the two, the resulting offspring is less fit in either location than the parents, so inbreeding within each population is reinforced. In animals, inbreeding has been noted in the cheetah, which is so inbred that (again, another actual experiment) one can take skin from any cheetah and successfully graft it onto any other cheetah without rejection. Their genomes show very low heterogeneity, if I recall correctly one of the lowest of all mammals. A hypothesis in this situation is that the majority of the deleterious alleles have already been eliminated from the population (fixed at 0). Granted, hunting by human beings probably hasn't helped the situation. Without inbreeding, sympatric speciation (speciation where the parent and new species are not separated geographically) would be difficult to impossible.

As for clownfish, seeing as how they do not widely disperse in the wild, I would not be surprised to find many small wild populations that show low heterogeneity. Remember we're talking about a group of species where often, due to sex changes, a lost parent is replaced by an offspring (e.g. if the male dies, one of the juvenile offspring will pair with the female, its mother). My point is that without knowing the heterogeneity of the wild clownfish populations where they collect their parent stock, it's impossible to know if their breeding methods significantly increase the rate of sib or parent mating from the wild. I also don't know of any connection between barring patterns and strongly deleterious alleles. As for "benefit of the species" I think that is beside the point, as captive clownfish are completely reproductively isolated from their wild counterparts. From an ecological standpoint they're as good as dead, especially in that unlike a cat or dog they're not going to go feral (god help us) and overrun the city streets :). Welfare of individuals is important, we are morally responsible for the well-being of our livestock, but if concern for the species as a whole is foremost then the possibility of fixation of deleterious alleles from inbreeding captives shouldn't be a large concern, it should be protecting wild populations from overharvesting. I also highly doubt that ORA is going to risk their all of their broodstock to inbreeding depression.
Click to expand...

Firstly, if you could find the references you're speaking of, I would love to read them, please forwrad them to me. But I think you are misapplying the inbreeding principle. Of course, scale is everything, and we can, of course, say inbreeding occurs no matter what because of common ancestry millions of years ago. However, would you not agree that the level of differention and specializiation between isolated populations does not establish in am ere two or three generations? Or ten, or twenty? But instead, hundreds? This is the core of my viewpoint. Inbreeding will only ahve the beenfits you describe in the LONG term, not in the short term of less thana decade. This is where my contention of dmoesticated selcetive breeding vs. wild selective breeding comes into play.
I would disagree that clownfish inbreed in the wild. With the pelagic phase of their deveopment, I would suggest the offspring scatter distantly through the area, and a mere fraction of the offspring survive, so the likelihood for animals with direct relatedness actually pairing and breeding is quite low, not high as you have suggested. The evidence I can show is that of the millions of clownfish that are caught in the wild, how many misbars, hunchbacks, or picasso are seen? Few if any. Yet, how can ORA (or whoever) create hunderds of them a year (or less)? The answer is simple.
as for ORA risking their livestock, you are overlooking a major point- they will not see the results as they sell their offspring! And even if they would depress the "quality", why wouldnt they risk it? How much money ahve they made already for mselling a genetically wasteful animal for a big premium? I think you are giving ORA more credit than they are worth. Hey, if I was seeing the money they were, I might reconsider my morals too, and this is the issue. Money talks, and morals defintiely do not pay the bills. Especially in a marginally profitable profession such as fish breeding.
 
Hm, I admit I'm not as knowledgeable about the clownfish life cycle as I would like. I assumed they did not disperse very widely as juveniles due to the fact that clownfish in general are relatively poor open water swimmers. My impression was that many of the offspring congregate in groups of juveniles, trying to establish dominance for when the opportunity arises. Is this incorrect? I agree that in any case survival would be very low. As for why they do not appear to be present in the wild, perhaps there is a sexual selection effect where they find it difficult to pair (I think this unlikely). Its indisuptable that their breeding practices are reliably producing the desired pattern morphs. I'm not familiar with hunchbacks, is it deleterious or cosmetic?

I think the scale at which inbreeding has deleterious effects depends entirely on the organism in question. Some organisms, such as some plants, self almost exclusively. I don't know enough about the genetics of fish to say what their threshold is. I'll try to find a citation for the cheetah paper.

Another thought: could the pattern morphs be a result of environment in any way in addition to genetics? Perhaps the pattern morph results from some condition of the breeding facilities (water temperature, stress or lack thereof). I don't know much about ORA's business practices, but I'm assuming they would notice any severely malformed batches before they left their facilities. I agree that dollar signs can definitely override ethics.
 
Clownfish bio9logy really doesnt condone inbreeding at all. The fry are pelagic for approx 8 days, where they consume microplankton out of the water column. They are actually drawn into the water column by the moonlight, so they are the currents mercy. Once they metamorphose into juviniles, they seek shelter in an abandoned anemone, or as a subservient juvi with a dominant pair present. This is if they are extremely lucky and havent perished first. If the pair is disrupted, and the female is lost, then perhaps the juvi will become a male (never a female without being the amle first). You can imagine, the statistical probability of this fry landing in his parent anemone after 8 days in the water column, and succceding his father, are quite imporbably small.

Regarding lants, it is not my forte, but I have spoken to the hoprticulturist I work with, and he has mentioned that the cultivars, hybrids, and selected traitrs are quite intensively managed by humans, not the plantrs. He indicated if the plants were left to their own vices, they would possibly be able to create a more true variant, but it would take "forever".

I wont comment much on the cheetahs, until you can get me a link or title or something so I can read the paper, but I am guessing this is a recently (in the past 100 years) isolated colony which is escaping community extinction by inbreeding. However, I would argue that the effects on fecundit, fitness, and viability, have not likely been determined yet. But I will reserve any more comment until I read the paper.

Getting back to ORA in particular, they are quite proud of their picasso clowns (which are aberrant colors not induced by any environmnetal factor), naked clowns (the same conditions as picassos), and their "stubby" clowns, which they boast are actually missing vertebrae from their spine. Now, while the aberrant colors are surely no ill effect as these are not wild fish, how are they miraculously creating multiple broods of these fish which are abberants. This, by defnition means anomolous physical conditions. How can something tyhat is anomolous be suddenly predictable and repeatable? However, I would argue stringly that the "stubby" clowns are in fact of reduced fitness, as there has been an anatomical alteration which is directly related to the nervous system, the locomotion, and the social impacts of this fish. How are these repetitively reoccuring? I think we all know the answer to that.
 
The cheetah paper I was thinking about is:

O’Brien SJ, Roelke ME, Marker L, Newman A, Winkler CA. 1985. Genetic basis for species vulnerability in the cheetah. Science 227:1428–34

Which is covered in a review by the same author in:

SJ O'Brien, WE Johnson. 2005. Big cat genomics. Annual Review of Genomics and Human Genetics.
"Yet one species, the African cheetah, showed little difference in the incidence of infant mortality between related and unrelated parents. All cheetah matings—unrelated and consanguineous—resulted in 30% to 40% infant mortality, the highest level seen in Ralls’ survey for unrelated matings (70, 71). Cheetahs, it turned out, appeared to have naturally inbred with 90% to 99% reduction of overall genetic diversity as measured by allozymes two-dimentional protein electrophoresis (2DE) of fibroblast proteins, RFLP variants at the major histocompatibility complex (MHC), and SNP sequencing (estimated by random shotgun sequencing of cheetah genomic DNA; K. Lindblad-Toh, personal communication). Perhaps the most dramatic affirmation of the cheetah’s genetic uniformity was the demonstration that reciprocal skin grafts, surgically exchanged between 12 unrelated cheetahs, were accepted by their immune systems as if they were identical twins (70). The cheetah’s MHC, which specifies class I and II cell surface antigens that trigger graft rejections in all other mammals, alleles were all the same, an extraordinary discovery for a free-ranging species. Somehow the ancestors of modern cheetahs off-loaded most of their endemic genomic diversity, so breeding between siblings today has a minimal effect on an already elevated juvenile mortality."

It goes on to estimate a population bottleneck about 10,000 years ago and a BioScience paper titled "Surprising Cheetah Genetics" quoted O'Brien as comparing their homogeneity to that of lab mice. Another paper (B Keane, SR Creel, PM Waser. 2004. No evidence of inbreeding avoidance or inbreeding depression in a social carnivore. Behavioral Ecology) found a situation in dwarf mongoose:

"Theory suggests that animals will not necessarily evolve to
avoid inbreeding, since avoiding inbreeding may have costs
that outweigh the benefits (Bengtsson, 1978; Waser et al.,
1986). In social carnivores, the costs of avoiding inbreeding
include the risk of starvation or predation during dispersal,
the risk of aggression during immigration into packs containing
non-relatives, and the loss of indirect fitness. For Serengeti
dwarf mongooses, these costs are now high. If they were equally
high in the ancestors of present-day dwarf mongooses, restricted
dispersal and repeated dispersal within local clusters
of packs could have been favored despite the genetic cost of
mating with relatives. If the cost to inbreeding in ancestral
mongooses was caused by the unmasking of deleterious alleles,
then continued inbreeding would have reduced the cost
of inbreeding in succeeding generations. Lack of disassortatrve
mating within packs would then reflect both a lack of
opportunities for outbreeding and a lack of strong selection
against inbreeding.
In 1983, Cheney and Seyfarth suggested that non-random
dispersal among primate groups could potentially elevate,
rather than reduce, relatedness within a group. Our results
confirm that their suggestion also applies to a pack-living carnivore.
Mechanisms that could produce this result include selective
transfer to groups containing siblings, to adjacent
groups, or to particular groups linked by safe corridors."


My point here is that inbreeding does occur in the wild, and while it can be and, outside of plants, usually is deleterious, it isn't necessarily so.
 
Forgot to comment about the "stubby" clowns... yeah, that's definitely genetic and probably deleterious. Whether or not it's deleterious enough in an aquarium environment to make a difference in survival or quality of life I don't know, but it wouldn't surprise me. I agree that I find those in particular ethically problematic (and they're not even attractive!)
 
LockeOak;127560 wrote: The cheetah paper I was thinking about is:

O’Brien SJ, Roelke ME, Marker L, Newman A, Winkler CA. 1985. Genetic basis for species vulnerability in the cheetah. Science 227:1428–34

Which is covered in a review by the same author in:

SJ O'Brien, WE Johnson. 2005. Big cat genomics. Annual Review of Genomics and Human Genetics.
"Yet one species, the African cheetah, showed little difference in the incidence of infant mortality between related and unrelated parents. All cheetah matings—unrelated and consanguineous—resulted in 30% to 40% infant mortality, the highest level seen in Ralls’ survey for unrelated matings (70, 71). Cheetahs, it turned out, appeared to have naturally inbred with 90% to 99% reduction of overall genetic diversity as measured by allozymes two-dimentional protein electrophoresis (2DE) of fibroblast proteins, RFLP variants at the major histocompatibility complex (MHC), and SNP sequencing (estimated by random shotgun sequencing of cheetah genomic DNA; K. Lindblad-Toh, personal communication). Perhaps the most dramatic affirmation of the cheetah’s genetic uniformity was the demonstration that reciprocal skin grafts, surgically exchanged between 12 unrelated cheetahs, were accepted by their immune systems as if they were identical twins (70). The cheetah’s MHC, which specifies class I and II cell surface antigens that trigger graft rejections in all other mammals, alleles were all the same, an extraordinary discovery for a free-ranging species. Somehow the ancestors of modern cheetahs off-loaded most of their endemic genomic diversity, so breeding between siblings today has a minimal effect on an already elevated juvenile mortality."

It goes on to estimate a population bottleneck about 10,000 years ago and a BioScience paper titled "Surprising Cheetah Genetics" quoted O'Brien as comparing their homogeneity to that of lab mice. Another paper (B Keane, SR Creel, PM Waser. 2004. No evidence of inbreeding avoidance or inbreeding depression in a social carnivore. Behavioral Ecology) found a situation in dwarf mongoose:

"Theory suggests that animals will not necessarily evolve to
avoid inbreeding, since avoiding inbreeding may have costs
that outweigh the benefits (Bengtsson, 1978; Waser et al.,
1986). In social carnivores, the costs of avoiding inbreeding
include the risk of starvation or predation during dispersal,
the risk of aggression during immigration into packs containing
non-relatives, and the loss of indirect fitness. For Serengeti
dwarf mongooses, these costs are now high. If they were equally
high in the ancestors of present-day dwarf mongooses, restricted
dispersal and repeated dispersal within local clusters
of packs could have been favored despite the genetic cost of
mating with relatives. If the cost to inbreeding in ancestral
mongooses was caused by the unmasking of deleterious alleles,
then continued inbreeding would have reduced the cost
of inbreeding in succeeding generations. Lack of disassortatrve
mating within packs would then reflect both a lack of
opportunities for outbreeding and a lack of strong selection
against inbreeding.
In 1983, Cheney and Seyfarth suggested that non-random
dispersal among primate groups could potentially elevate,
rather than reduce, relatedness within a group. Our results
confirm that their suggestion also applies to a pack-living carnivore.
Mechanisms that could produce this result include selective
transfer to groups containing siblings, to adjacent
groups, or to particular groups linked by safe corridors."


My point here is that inbreeding does occur in the wild, and while it can be and, outside of plants, usually is deleterious, it isn't necessarily so.
Click to expand...

Interesting papers. I dont necessarily agree with the deductions, and I will forwrad them to some of my professors nack in NY, and see what their take is on them to. I tend to think that some of the things stated are digestible, provided we only look at these populations, rather than the species as a whole, or that we only look for 2 or 3 generations, not 30 or 40 down the road. I would almost guarantee that dleeterious effects will be seen within this species or population, as compard to those who outbreed.

regarding the Cheetahs, from what I took from that paper is NOT that inbreeding isnt causing bad effects, it is just that inbreeding has been prevalent for so long in these isolated populations, that the negative effects are now common traits, even if outbreeding occurs. This is the same road the mongoose etc will be in in 200 or 300 years I presume.
 
You must log in or register to reply here.
Back
Top