Inbreeding in wild populations ?
- Thread starter zooman
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Normaly inbreeding in wild populations is quite rare but it depends on how large ( or small ) the population is. With only one or two pairs of a surtain species left, inbreeding will have to take place if the species want to survaive !
In larger populations this is much less the case and most species have strategies to avoid inbreeding for example males which get mature have to leave the group.
If a small population is left ( or reach ) in a sutain area without the possibility to pair with other specimens of their species, it is well possible that new (sub) species develope.
In larger populations this is much less the case and most species have strategies to avoid inbreeding for example males which get mature have to leave the group.
If a small population is left ( or reach ) in a sutain area without the possibility to pair with other specimens of their species, it is well possible that new (sub) species develope.
Is this based on scientific evidence? I think that there is much inbreeding. Animals from a group will disperse to neighbouring groups, where in the past related animals have also dispersed to. There are species that only live along rivers, they can only disperse northwards or southwards, where they will also meet related animals. So I think that inbreeding is very common. It could be the basis of benificial mutations, making the species stronger and guiding evolution. Negative effects of inbreeding will be disappear through natural selection.
in a very broad sense, I'd say, this is how sub-species come about. ;-)
Inbreeding is usually defined as closely related animals interbreeding (i.e. siblings, cousins, and offspring to parents or grandparents). Most species have mechanisms in place to discourage inbreeding, dispersal being a common one, as mentioned above.
Any breeding will produce genetic mutations. Beneficial mutations, and those that have no noticeable effect, will usually persist in the population. If the mutation is deleterious (=non-beneficial) then it will usually die out. However, inbreeding results in an increase in the frequency of mutated genes, including the deleterious ones, which is why inbreeding is detrimental to a population's survival.
New species (or subspecies) occur when their genetic makeup changes to adapt to different circumstances. New mutations that are beneficial will increase in frequency within the population until all or most of the population have the mutation. Inbreeding will speed up this process, but is not the creator of the process. In fact, inbreeding could slow the process down by producing unfit individuals who die early, or don't breed at all(i.e wasted effort).
Hix
Any breeding will produce genetic mutations. Beneficial mutations, and those that have no noticeable effect, will usually persist in the population. If the mutation is deleterious (=non-beneficial) then it will usually die out. However, inbreeding results in an increase in the frequency of mutated genes, including the deleterious ones, which is why inbreeding is detrimental to a population's survival.
New species (or subspecies) occur when their genetic makeup changes to adapt to different circumstances. New mutations that are beneficial will increase in frequency within the population until all or most of the population have the mutation. Inbreeding will speed up this process, but is not the creator of the process. In fact, inbreeding could slow the process down by producing unfit individuals who die early, or don't breed at all(i.e wasted effort).
Hix
Broadly speaking, I'd say that covers the distinction of the Florida Panther. Maybe a few other subspecies whose distinctions are based on geographic isolation from other populations. I suspect that isolation, genetically speaking, is what people speak of when noting those distinctions. I.e Amur Tiger vis Caspian Tiger or Indochonese vis Malayian vis Bengal. A broad palate with several bold colors that gradually smear in between. In a broad sense evidence of breeding within a geographic grouping. With a wink an a nod, some of what we refer to as subspecies are really just examples of kissing cousins. It's when the isolation combines with a very small population that the negative effects show up. In Florida this was off set by the introduction of Texas Cougars to infuse more genetic diversity in the population. Now...did that alter the subspecies designation of the Florida Panther or otherwise diminish the conservation value of the population? I'd say no. I'm a "lumper" when it comes to continental populations and raise an eyebrow at subspecies designations that are confirmed only though genetics. Given enough time this may lead to new species, but I think it's more likely evidence of habitat loss effecting the natural interchange of genetic material.
Well, now you only talk about adaption to circumstances. Mutations do not always have an effect on the fitness of an animal, let's just take an example of the moustache of a emperor tamarin. And if a mutation has no negative effects, then inbreeding can speed up the process of change. We see that in populations of primate species that are at the border of their distribution range, which is limited by a river. In some area group members can only disperse into one direction, resulting in more inbreeding. Here we often see a bleaching occuring, with no evidence that this bleaching is decreasing their fitness.
Many mutations are neutral, for example replacing one amino acid by another in an enzyme (provided it does not happen near the active site or an important structural region). However I doubt if the emperor tamarin's moustache has no effect: I think it must aid species recognition and prevent hybridisation at the least.
Alan
Inbreeding in wild populations
A majority of inbred laboratory animal populations go extinct. Some get through a genetic bottleneck and become really useful laboratory animals because of being very similar and thus easily comparable for experimental purposes. Small pockets of wild animals, isolated from others of their kind, are also likely to go extinct.
A majority of inbred laboratory animal populations go extinct. Some get through a genetic bottleneck and become really useful laboratory animals because of being very similar and thus easily comparable for experimental purposes. Small pockets of wild animals, isolated from others of their kind, are also likely to go extinct.
But then you are talking about massive inbreeding, many generations. I once worked in a zoo where the owner said: you can inbreed until they stop breeding; then it is time to introduce new animals. GREAT MANAGEMENT
I have often wondered about this very thing with amphibians in small ponds, the population has to return to breed in the same place each year and it occurs to me there must be an element of in breeding if the adult populations dip from natural or accidental die off from year to year.
I once kept rocket frogs, the originals had been collected under license from Trinidad, a few years down the line I got some of the offspring, and my nuclease of 1:4:0 eventually produced a good 3 or 4 hundred, some I passed on to other keepers. I noticed no difference until I had had them about 5 years when they started to throw out the odd pale orange ones that lacked most of the brown colouring of the adults, and had clear eyes, they seamed to do OK, but never thrived. Over the next year a few more started to appear, sadly I lost the lot when the power failed while I was away and the water dropped to below 50oF and they all perished. So i will never know if they were as fertile as the parents had been, or if they were sterile.
I once kept rocket frogs, the originals had been collected under license from Trinidad, a few years down the line I got some of the offspring, and my nuclease of 1:4:0 eventually produced a good 3 or 4 hundred, some I passed on to other keepers. I noticed no difference until I had had them about 5 years when they started to throw out the odd pale orange ones that lacked most of the brown colouring of the adults, and had clear eyes, they seamed to do OK, but never thrived. Over the next year a few more started to appear, sadly I lost the lot when the power failed while I was away and the water dropped to below 50oF and they all perished. So i will never know if they were as fertile as the parents had been, or if they were sterile.
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I should've mentioned, many small, isolated animal populations, such as those on islands, are prone to inbreeding. I saw a documentary about an island bird called the black robin, that at one point was reduced to only a few individuals, with one breeding female. There are about 200 now, and they don't seem to be suffering from inbreeding depression. Apparently this kind of thing appears in these small island animal populations, where it doesn't take much for most of the population to get wiped out. A population inbreeds so much that all of the bad recessive genes normally associated with inbreeding eventually get forced out through natural selection. I think this was also observed in a rabbit population somewhere in Japan, where they're all descended from just two rabbits.
Sorry Hix my mistake
I should also mention our pond full of European Sticklebacks Gasteroteus aculeatus, a small fish in case any one is wondering. I bought 2 in 1998 and from those 2 I have bread thousands, some I sold to a pet shop at 50p each, some went to friends ponds, after a die off here I was able to bring some from a friends pond to re establish them again.
The only difference is they aren't as large as wild ones being about 2/3rds as large, but that could be due to the smaller pond and more restricted food supply than they would get in the wild.
I should also mention our pond full of European Sticklebacks Gasteroteus aculeatus, a small fish in case any one is wondering. I bought 2 in 1998 and from those 2 I have bread thousands, some I sold to a pet shop at 50p each, some went to friends ponds, after a die off here I was able to bring some from a friends pond to re establish them again.
The only difference is they aren't as large as wild ones being about 2/3rds as large, but that could be due to the smaller pond and more restricted food supply than they would get in the wild.
As I said before, every breeding produces some genetic mutations, many of them benign. Every individual produced has its own little mutations so species that produce lots of offspring, and can reproduce again quickly (like fish, frogs, mice), are creating genetic diversity within the population with each breeding. Species that can do this can cope with inbreeding better than species that produce one or only a few offspring once a year. Species that produce one offspring every two years need to have a large population initially.
Hix
zooboy28
Well-Known Member
This seems to be a common misconception here. When a small number of individuals colonise a new area, like an island, they undergo a bottleneck called the founder effect, where genetic diversity is lowered compared to the source population - due to the small number of founders only bringing a subset of the diversity with them, and the further loss due to drift in small populations. As the population expands, there may be some initial inbreeding, but this would quickly drop off as the population's level of relatedness drops over generations and its size increases (meaning more mates are available). Most "inbred" animals would be lost from the population fairly early, either because they do not survive, or fail to reproduce.
And this brings me to another misconception here. An animal is inbred if its parents were closely related. However, any offspring it has will only be inbred if it mates with a close relative. So an inbred animal is not of no use to a captive breeding programme, as long as it is bred with an unrelated animal (and as long as it has not been inbred for the last ten generations and has built up a massive genetic load). Any managed captive population will be managed to minimise inbreeding and maximise diversity, and for good reason - offspring resulting from a father/daughter mix have a 50% reduction in expected survival, most of this mortality occurs before an animal is born.
Inbreeding in wild populations is relatively rare, as most species actively avoid it through all kinds of mechanisms - dipsersal, kin avoidance, etc. It really only becomes a problem when a population becomes small and isolated - a scenario that is becoming increasingly common for many wild populations today.
If a species arrives on an island with only a few individuals, then the resulting population will quickly become inbred. But as you explained, once the population grows beyond this then outbreeding begins. But they would still have started from a small founder base.
That seems to be the key issue. A rapid population growth is needed that then enables individual animals to mate with others that are not closely related. Also not all health problems in a small population can be attributed to inbreeding. If a particular genetic disorder occurs that is dominant, especially if affected animals still survive to breed then it will quickly spread through a small population but that is not a result of inbreeding but rather a result of the smallness of the population.
An example of this in humans would be the spread of Haemophilia in Europes royal families in the 19th and early 20th centuary. That did not occurr because of inbreeding as critics of royals would attest but simply the natural spread of a genetic disease within a small population