Inbreeding depression

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   It is interesting to note that it has been proved that in small isolated populations of sand lizards in Sweden, matings between siblings were shown to result in relatively high numbers of malformed offspring (which die in a short time). This work was, I think done by Olssen and Gulleberg if I recall righly.

It would seem to be wise to at least seriously consider the possibility of captive breeding and/ or translocation of commoner species to sites that have been isolated for some time. Sites could be considered as ranging from large areas with a good matrix of links, supporting a high metapopulation - at one end of the scale - through to small sites surrounded by intense urbanisation. These may be as cut off - for population transfer potential - as islands in the sea. For the many and varied range of sites falling inbetween these two extremes, one would expect that making and enhancing habitat links where possible would be the preferred option as far as naturalness goes. One would dare to hope that the forthcoming changes to CAP subsidies (more emphasis on agri-environment works) could go some way to helping bring this about in rural areas. 

In cases of isolated sites with no likely potential for linking existed, and where animals might to be introduced to boost the gene pool, one would want to be reasonably sure that the population on site was not dying out due to some other pressure such as cat predation or habitat decline (both of which may be big influences in many cases). Starting a programme of captive breeding and translocation would also imply monitoring of results to evaluate success, and assuming sites remained isolated, one would expect that there would come a time in the future when there would once more be a need for new animals to boost genetic variation of the population, so there might effectively be a need for an ongong cycle of transferes which mimics a natural flow of animals between populations within a meta population. An interesting idea - certainly very artificial (but the problem of isolation has been brought about by humans in the first place) - but it might become vital as a means of saving spicies in certain areas. The alternative could be to resign ourselves to the fact that many reptiles will tend to die out in their surviving pockets in areas with high human populations.

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davecowley Members Profile Send Private Message Find Members Posts Add to Buddy List Member Joined: 23 Jul 2003 Location: United Kingdom Status: Offline Points: 3	Post Options Post Reply Quote davecowley Report Post Thanks(0) Quote Reply Posted: 04 Aug 2003 at 12:16pm
	It is interesting to note that it has been proved that in small isolated populations of sand lizards in Sweden, matings between siblings were shown to result in relatively high numbers of malformed offspring (which die in a short time). This work was, I think done by Olssen and Gulleberg if I recall righly. It would seem to be wise to at least seriously consider the possibility of captive breeding and/ or translocation of commoner species to sites that have been isolated for some time. Sites could be considered as ranging from large areas with a good matrix of links, supporting a high metapopulation - at one end of the scale - through to small sites surrounded by intense urbanisation. These may be as cut off - for population transfer potential - as islands in the sea. For the many and varied range of sites falling inbetween these two extremes, one would expect that making and enhancing habitat links where possible would be the preferred option as far as naturalness goes. One would dare to hope that the forthcoming changes to CAP subsidies (more emphasis on agri-environment works) could go some way to helping bring this about in rural areas. In cases of isolated sites with no likely potential for linking existed, and where animals might to be introduced to boost the gene pool, one would want to be reasonably sure that the population on site was not dying out due to some other pressure such as cat predation or habitat decline (both of which may be big influences in many cases). Starting a programme of captive breeding and translocation would also imply monitoring of results to evaluate success, and assuming sites remained isolated, one would expect that there would come a time in the future when there would once more be a need for new animals to boost genetic variation of the population, so there might effectively be a need for an ongong cycle of transferes which mimics a natural flow of animals between populations within a meta population. An interesting idea - certainly very artificial (but the problem of isolation has been brought about by humans in the first place) - but it might become vital as a means of saving spicies in certain areas. The alternative could be to resign ourselves to the fact that many reptiles will tend to die out in their surviving pockets in areas with high human populations. Print size increased to help read. Edited by Moderator

laighleas Members Profile Send Private Message Find Members Posts Add to Buddy List Member Joined: 01 May 2004 Location: United Kingdom Status: Offline Points: 1	Post Options Post Reply Quote laighleas Report Post Thanks(0) Quote Reply Posted: 04 May 2004 at 12:02pm
	I remember seeing something similar on the demise of the Swallowtail butterfly in the UK. As habitats became more fragmented, and more distant from each other, the butterflies became less strong fliers, and thus moved around considerably less, very rarely leaving their patch. I suppose that selection favoured those individuals that stayed where they were, since they could breed. A strong flier that left its particular patch probably has a reduced or nil chance of breeding. Eventually you wind up with a population that remains very local - with potential problems of inbreeding - even if conservation exercises now mean that there are increased opportunities for greater movement. Consequently it may not be enough to simply improve habitats if this process is already underway - the species may still decline because it can no longer take advantage of the enlarged habitat.

calumma Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 27 Jun 2003 Location: United Kingdom Status: Offline Points: 375	Post Options Post Reply Quote calumma Report Post Thanks(0) Quote Reply Posted: 04 May 2004 at 5:26pm
	One concern I have here is the inappropriate application of 'genetic conservation' using animals that originate from development sites. A whole heap of work is required before this strategy can be promoted. Given the difficulties of finding (let alone preparing) appropriate receptor sites I can see the gleam in many a planning consultants eye...
	Lee Brady Kent Herpetofauna Recorder \| Independent Ecological Consultant Email

administrator Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Joined: 01 Jan 2007 Status: Offline Points: 10	Post Options Post Reply Quote administrator Report Post Thanks(0) Quote Reply Posted: 04 May 2004 at 8:57pm
	Good point Lee, any attempt at establishing whether or not 'genetic conservation' would provide a viable tool for future herpetological conservation lies in the realms of scientific research, not the translocation of animals for mitigation purposes. Those familiar with the Madsen study will realise that the adult males used to introduce the novel gene to the ailing population were in-fact returned to the donor site after mating occurred with the receptor site females. The donor site was that which was identified as the 'nearest large population' to the isolated site. We are not talking here about consultants collecting up adder in buckets and dumping them at their discretion in the name of genetic conservation. We are talking about individual isolated sites that have no prospect of introduction of novel genes through 'natural' mechanisms that will inevitably be lost in the years to come. I can think of number of sites off the top of my head where I would be amazed if any form of genetic flow occurs. Clearly no such work should be carried out without: 1) Scientific evidence that the receptor site is loosing viability due to the demonstrable affects of inbreeding depression. 2) long term study of the receptor sites recovery (5-10 years) would clearly be essential. 3) The animals possessing the 'donor novel genes' being returned to their original population in time. Not exactly the realms of a consultant looking for a dumping ground. Tony I'm a 100% in agreement that long distant translocation must be avoided at all costs and refer again to the Madsen study and the use of the 'nearest large population' for donor genes. I also hope that the work currently being carried out will give a body of evidence to show that on the whole adder are managing to remain genetically diverse. I still believe however we will see the extinction of some isolated populations particularly in urbanised and agricultural areas, due to the affects of inbreeding depression.

miccomte Members Profile Send Private Message Find Members Posts Add to Buddy List Member Joined: 02 Dec 2010 Location: Germany Status: Offline Points: 1	Post Options Post Reply Quote miccomte Report Post Thanks(0) Quote Reply Posted: 02 Dec 2010 at 12:43pm
	Hello, To be sure to know what you are speaking about, it's good to know how inbreeding is actually computed. Here it is: Inbredding