The unwanted ending … inbreeding 近親繁殖 - 貂

圖文網誌無音樂:http://www.wretch.cc/blog/polecatsoQ/14489576
　　這篇文章擷取於< Ferret Husbandry, Medicine and Surgery >，在討論近親
繁殖。會特別先把這段文字分享出來，真的是最近聽到一件很寒心的事情。這幾年
來越來越多貂賣家，其中有已經繁殖到好幾代的、也有今年才生第一胎的。不管你
是今年才養貂還是很多年前就養貂的，您知道您的血緣來自於何處嗎？您知道您購
買小孩的最源頭來自於哪裡嗎？不要認為網路上徵配台北寵物店買的和屏東寵物店
買的就不會有關係，試想一下中盤商收購貂去了哪裡？

　　不管您買貂是要生小孩或是結紮純粹陪伴自己，請您一定要看這段文。不要認
為結紮了就是小事，近親貂結紮了還是存在著免疫系統異常、抵抗病毒侵入能力降
低；而有想過要抱小貂寶寶的低出生率、新生兒的高死亡率，您或許覺得生有活就
賺到、生了死了也沒差嗎？發情、配種、懷孕到生產這過程母貂承受多少痛楚？

　　整篇大概在敘述現代的貂刻意的培育已經遠離原始基因。後面提到澳洲原有豐
富的品種但從２０世紀初因為政策關係沒有新血緣進入澳洲，最危險的事造成基因
缺陷/弱化和近親繁殖。說明為什麼澳洲政府不容許進口，原因是可能會傳入可怕的
阿留申病毒。然後提到近親的後果才又回頭說近親的
因素。


The unwanted ending … inbreeding

The modern ferret is becoming increasingly removed from its original
genetic pool by breeding, including inbreeding, for certain features. The
ferret genetic pool needs refreshment by outbreeding to new ferret lines.
The outlook for the Australian scene is that we had a variety of ferret
(ferret-polecat?) strains coming in during the nineteenth and early
twentieth centuries but no new bloodlines have been introduced for some
decades. We have had years of interbreeding with this basic stock, but the
danger is genetic weakness and inbreeding effects.
We could consider that there is a population of inbred ferrets in
WesternAustralia (where I live) and another in distant Tasmania where
Christina Bernard with her interest in ferret genetics, lives. We would
like to improve Australian ferrets by introduction of new blood lines but
quarantine laws do not allow this. The possibility of inadvertent
introduction of Aleutian disease, a chronic parvovirus disease, would be
devastating (Ch. 8).
Bernard considers that genetic fitness has no correlation with physical
fitness and is the overall ability to leave surviving offspring who themselves
will be able to reproduce themselves successfully. The signs of inbreeding
would show as reduced fertility, increased congenital defects, 'bent-nose'
condition, lower birth rate, higher neonatal mortality, smaller adult size
and loss of immune system function. Some of these traits had been found in
the Russian domestication experiments. 近親繁殖會造成生育力降低、先天基因缺陷
提高、歪鼻子、低生育率、新生兒死亡率高、成體較正常小和普遍性的免疫系統異常。
The outcome for individuals with 'weak' genes is a deficient immunological
system unable to prevent infecti on particularly by viruses. 缺乏免疫系統無法
防止感染，尤其是經由病毒感染的疾病。 Inbred laboratory animals, mice, etc.
need to be in a sterile environment. 需在無菌的環境裡 Endangered wild animals,
in decreased numbers, are at risk of being wiped out by epidemics due to
decreased immunological protection caused by unavoidable inbreed.
The function of the immune system is to recognize foreign invaders
to the body and destroy them by producing antibodies. The ability of the
immune system to recognize foreign antigens depends on the genetic diversity
of the major histocompatibility complex (MHC) genes. These are positioned
close together on one chromosome and are inherited together as a unit called
a haplotype. The MHC of a ferret is polygenetic with many genes and the
alleles of each MHC gene are numerous within a population; it is polymorphic.
Each ferret has two MHC haplotypes, one from each parent. The alleles of
both haplotypes are expressed in a co-dominant manner, so greater diversity
between the parents' haplotypes will give the offspring a better functioning
immune system. Ferrets in an inbred population, with less diverse haplotypes,
are at risk of being unable to recognize and respond to the challenge of
infection.
In the wild, the alleles will be numerous and variable adding to the
genetic mix of the species concerned. In the event of disease, individuals
of the species would survive as they would have the right mix of genes to
overcome the infection and would pass that to their offspring, so more and
more pathogens would be recognizable. It is considered that over time, the
DNA can get stronger by changing or mutation and natural selection working
on the changes. In fact, the MHC genes do have a high mutation rate as they
are essential for species survival.

以上文字來自 Ferret Husbandry, Medicine and Surgery

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