# Problems with inbreeding/lack of genetic diversity?



## AFK

Have you guys ever noticed problems with this, and if so, how many generations in do you start noticing these problems? Surely, inbreeding can't be healthy.


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## Rick

Nope, never noticed a problem. I'm sure it doesn't hurt to get some new genes in there but it's not a problem.


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## anthony2001a

> Have you guys ever noticed problems with this, and if so, how many generations in do you start noticing these problems? Surely, inbreeding can't be healthy.


In the wild, an ooth will produce hundreds of mantids. Odds are that in a given area, a wild mantis will mate with a relative. Insects are very different from mammals and don't have the same issues as mammal interbreeding (like bad hips on dogs, retardation, etc.)

Anthony


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## AFK

Okay, I did some wiki-ing and it looks like the topic of inbreeding isn't so simple:

http://en.wikipedia.org/wiki/Inbreeding

Anyone wanna summarize the main points?  Like how and why it is sometimes beneficial or benign and why and how it is sometimes harmful? I've always thought that the biggest reason inbreeding in general is bad is because it makes the species prone to disease?


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## Rick

> Okay, I did some wiki-ing and it looks like the topic of inbreeding isn't so simple:http://en.wikipedia.org/wiki/Inbreeding
> 
> Anyone wanna summarize the main points?  Like how and why it is sometimes beneficial or benign and why and how it is sometimes harmful? I've always thought that the biggest reason inbreeding in general is bad is because it makes the species prone to disease?


Yeah but like we said we're talking about insects which I don't think it makes that big of a difference.


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## AFK

Okay, but now that only makes me wonder why insect genetics aren't as prone to inbreeding problems as mammals then? :?: :| :?:


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## Rick

> Okay, but now that only makes me wonder why insect genetics aren't as prone to inbreeding problems as mammals then? :?: :| :?:


Simpler life form?


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## AFK

I was thinking about that too, but that still doesn't pinpoint exactly why insects don't have this problem. If I understand correctly, there is less genetic material in insects in comparison to mammals, but I still don't see how genetic volume has an effect on basic principles of evolution/survival of the fittest (and in this case, in regards to resistance to disease). :?


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## chun

Inbreeding does and can have detrimental effects on insects, not just only mammals. Inbreeding increase the chances of homozygosity; subsequently increasing the chances of detrimental mutations/genes being expressed. The expressed homozygous deleterious phenotype can decrease the fitness of the organism.

Inbreeding can be beneficial as well, although this is rare. Inbreeding played a big role in domestication and selective breeding, by breeding heterozygous siblings to increase the chances of producing progenies with the dominant homozygous alleles/genes. For example, if one species of plant exhibit effective immune response to virus X, then it will have higher fitness. If this immune response is caused by homozygous recessive alleles, then inbreeding will definitely ensure that the progenies/offsprings would inherit this homozygotic advantage. Thus the offsprings will have a higher fitness, icnreasing its chances of surviving and reproducing itself. so therefore inbreeding can fix a desired advantageous traits into a population. Also inbreeding is used to fix a desired characteristic such as leaner meat in pigs.

If anything, the effect of inbreeding would "take its toll" quicker in insects than mammals due to its quicker generation time. For example, the marclays stick insect, _Extatosoma tiaratum _were considered "common" around the 70s; but over time, the number of _Extatosoma tiaratum_ kept by breeders and hobbyists decreased dramatically and this species was deemed rare at one point. Hatchlings were subjected to a high mortality rate and even if they did survive their first moults many did not survive till adulthood. The _Extatosoma tiaratum_ culture in the UK was very heavily inbred. Breeders around the world started trading ovas to increase the gene pool, and thus this species is still in the hobby today. When i started keeping mantids, i have kept some pretty exotic species such as _Hestiasula sp., Acanthop sp. _and _Majanga sp._. I havent seen these species in culture in years, due to breeders having trouble maintaining cultures past the third or fourth (even second) generations as the breeding stocks were became weak from inbreeding and eventually died.

Even though many of the mantids species are inbred, it doesnt mean detrimental inbreeding does not occur. Inbreeding doesnt always lead to deaths, deformaties or lower fitness, but the chances detrimental traits being expressed are higher.

"In the wild, an ooth will produce hundreds of mantids. Odds are that in a given area, a wild mantis will mate with a relative. Insects are very different from mammals and don't have the same issues as mammal interbreeding (like bad hips on dogs, retardation, etc.)"

In the wild, an ootheca will hatch out hundreds of mantids, but hatchlings tend to be extremely energetic and would no doubt be scurrying around. A mantid's habitat is huge, and the chances of a hundred lreated nymphs remaining in the same area is very very slim. Mantids do migrate, so if competition is high (so low food), then they will migrate to find new locations with lower competition (and higher food).

The rules of genetics are UNIVERSAL, it applies to every organisms. There are no differences between how our DNA works and how an insects DNA work. DNA replication, translation and transcription follow the same rules...The mechanism for DNA expression is the same in all eukaryotic organisms (organisms that are not bacteria/viruses). So insects will have the "same inssues as mammal inbreeding". Although insects do not get "bad hips" due to the fact that they do not have hips or an internal skeleton but deformaties do happen.

Insects and Mammals are faced with the same evolutionary pressures and genetic mechanisms, so inbreeding does make a big difference. So far that some species such as Hymenopus, the males mature much quicker than females to prevent inbreeding.

Sorry if this is a little bit confusing or unstructured (as i am writing this off the top of my head)...atleast it's better than revising

Peace

Chun


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## AFK

chun, great post! Thanks for the summary...makes perfect sense! In fact, that was all what I suspected, but I wanted to see and research it myself with mantis owners here. I also remember reading how _Hymenopus _males will mature a lot faster to prevent inbreeding too!  (which, by the way, is also congruent with your theory that mantises in general vastly spread out in large habitats, because from what I understand, _Hymenopus _seems to be a lot more static of a species, staying put on the same flower or something, so they have to evolve some other anti-inbreeding tactic in order to survive...that's just my theory though)

In regards to human selective breeding/inbreeding, whether it be with plants or pigs or domesticated dog breeds, I, myself, call that a form of "accelerated survival of the fittest." Because given a longer timeline with no human intervention, it could be said that that plant/pig/dog "breed" would have evolved anyway...it's just that humans decided to shorten this process from an otherwise thousands or more years to a few decades or less. But yeah, EVEN THEN, humans still need to be careful that the parents they are "inbreeding" with also won't be passing on outstandingly harmful traits.

With casual inbreeding, e.g. as found among exotic pets, most likely there isn't a carefully selective breeding program, so the danger is very much there. Again, it's a numbers game...it's playing with chance...but as probability dictates, given enough time, the probability becomes 100%. What is enough time though is what is chance.

This is also why I see this potentially problematic not just within mantis breeders, but also with the Giant Pandas in the zoos. I don't keep up with zoo news, and I really don't know, but are they inbreeding because it's just far easier at the moment, or are they already trying to find genes outside these panda's bloodlines? Of course, it's a balancing act of what's momentarily _feasible _and what can be _afforded _in the short-term and what's to _prevent _in the long-term.


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## Rick

Where did you get your info chun? I really don't think inbreeding will be an issue for the average hobbyist.


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## AFK

In related news, the Yangtze River dolphin was just very recently declared extinct (very recent as in just months ago). Very sad indeed, but even sadder was that scientists had already proclaimed the species DOOMED many many years ago...SIMPLY because the population had dropped to a point where genetic diversity had become beyond dangerously too low.  

Moral of the story: Genetic diversity is ESSENTIAL to a species's survival. If there are only a few members left of a species, we might be able to _*temporarily*_ increase the population from a few to maybe a hundred, but after that, chances are that the species will begin to mysteriously die off. It's not so mysterious when you consider the ACCUMULATED effects of inbreeding. Perhaps some of our mantis species in our culture "mysteriously die for no apparent reason" due to inbreeding problems? Just a theory.


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## AFK

Here's a counterpoint to consider though:

What about with bacteria that multiply from just a few or even one bacterium? Like a harmful bacteria infects a host, and it multiplies and multiplies. Can an entire population survive and thrive from just one parent?

Or is it the same where over time, that specific population will eventually begin to die off, and evolution will weed that bacterium out of existence?

Or maybe bacteria is different because bacteria mutates like there is no tomorrow.

I really don't know though...I'm no geneticist, but this is very interesting and also a potentially real problem in the hobby.


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## AFK

Okay, and what about animals, which are clearly not bacteria, that reproduce without mating? Like, aren't there mantises that are all females and reproduce on their own? How do they maintain genetic diversity then?


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## AFK

> Here's a counterpoint to consider though:What about with bacteria that multiply from just a few or even one bacterium? Like a harmful bacteria infects a host, and it multiplies and multiplies. Can an entire population survive and thrive from just one parent?
> 
> Or is it the same where over time, that specific population will eventually begin to die off, and evolution will weed that bacterium out of existence?
> 
> Or maybe bacteria is different because bacteria mutates like there is no tomorrow.
> 
> I really don't know though...I'm no geneticist, but this is very interesting and also a potentially real problem in the hobby.


Alright, I did some thinking and I think the case of bacteria multiplying within a host is not a valid comparison because bacteria that is already multiplying within a host obviously has already proven itself to have good genes since it was successful in infecting a host, so I guess it's already selective breeding in process. And bacteria don't need mates of different genetic make-up to reproduce...bacteria mutate like crazy, and this high mutation rate creates the genetic diversity. However, do higher animals, like some grass mantises, that reproduce without mating, create their own genetic diversity with high mutation rates too?


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## chun

i love this topic..it's getting me all excited about evolution (got my evolution exam in a week!)

Hmm, am in quite a rush atm; but i will definitely get back to this when i have (abit) more time


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## yen_saw

Based on my experience, it is far better chance on getting stronger and healthier batch of mantis if your breeding stock is from nymphs of a large hatching rate. So in a way, i am doing a "selective inbreeding", and have yet to see any detrimental effect, maybe the effect will show up after few more generations of "selective inbreeding". But the million dollars question is when's the "threshold" point.


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## AFK

> i love this topic..it's getting me all excited about evolution (got my evolution exam in a week!)Hmm, am in quite a rush atm; but i will definitely get back to this when i have (abit) more time


bump!


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## Asa

> Based on my experience, it is far better chance on getting stronger and healthier batch of mantis if your breeding stock is from nymphs of a large hatching rate. So in a way, i am doing a "selective inbreeding", and have yet to see any detrimental effect, maybe the effect will show up after few more generations of "selective inbreeding". But the million dollars question is when's the "threshold" point.


I'm betting pretty soon.


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## yen_saw

> Based on my experience, it is far better chance on getting stronger and healthier batch of mantis if your breeding stock is from nymphs of a large hatching rate. So in a way, i am doing a "selective inbreeding", and have yet to see any detrimental effect, maybe the effect will show up after few more generations of "selective inbreeding". But the million dollars question is when's the "threshold" point.
> 
> 
> 
> I'm betting pretty soon.
Click to expand...

How soon?! It takes a while just to breed a generation.


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## Asa

Maybe 3, 4, generations.


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## yen_saw

I am into the third generation for my orchid with "selective inbreeding" and hasn't seen any detrimental effect with inbreeding.


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## Asa

> I am into the third generation for my orchid with "selective inbreeding" and hasn't seen any detrimental effect with inbreeding.


Wow. With most species of insects, detrimental effects happen within a few generations. Maybe mantids are an exception to that rule.


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## OGIGA

> Wow. With most species of insects, detrimental effects happen within a few generations. Maybe mantids are an exception to that rule.


Really? Which insects?


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## Asa

Beetles, arachnids, anthropods.


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## colddigger

> I am into the third generation for my orchid with "selective inbreeding" and hasn't seen any detrimental effect with inbreeding.
> 
> 
> 
> Wow. With most species of insects, detrimental effects happen within a few generations. Maybe mantids are an exception to that rule.
Click to expand...

well you know, the mantis is the hick of the insect world...


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## athicks

> well you know, the mantis is the hick of the insect world...


lol!

I'm sure that there would have to be problems with lack of genetic diversity eventually. But in the short term there is not as many complicated things to mess up... like a complex nervous system. So the problems of inbreeding may not be pronounced or great after only a few generations.

Also, some of these rare mantids don't have huge populations in the wild right? I mean, it may be that they inbreed often there as well. It may be a genetically selected trait to NOT be affected by inbreeding!


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## Asa

> well you know, the mantis is the hick of the insect world...
> 
> 
> 
> lol!
> 
> I'm sure that there would have to be problems with lack of genetic diversity eventually. But in the short term there is not as many complicated things to mess up... like a complex nervous system. So the problems of inbreeding may not be pronounced or great after only a few generations.
> 
> Also, some of these rare mantids don't have huge populations in the wild right? I mean, it may be that they inbreed often there as well. It may be a genetically selected trait to NOT be affected by inbreeding!
Click to expand...

As mantids have different mating patterns, they do not interbreed often in the wild. The effects are not very pronounced in a few generations, but they are visible within most species.


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## Hypoponera

One possible reason you don't see the effects of inbreeding is numbers. How many eggs are in an ootheca? Perhaps the eggs that contain genetic problems simply die in the ootheca. Thus, you do not see any individuals with problems. This might explain why a large ootheca does not produce as many nymphs as expected.


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