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Author Topic: Ugrozene i nestale vrste  (Read 24839 times)

Offline saulosi

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Re: Ugrozene i nestale vrste
« Reply #30 on: 14 January, 2006, 12:08:17 »
Santa hvala na korekciji u pravu si za jednu stvar, heterozis se mnogo cesce(gotovo uvijek) ispoljava prilikom ukrstanja ratlicitih rasa ili linija sa visokom homozigotnoscu a velikom medjusobnom razlikom izmedju istih.I zato jedno izvinjenje.
Ona prica za svinjei goveda i dalje vazi.
Sto se tice heterozisa,on se jos naziva i hibridni vigor sto jasno ukazuje da se mnogo cesce pojavljuje kod hibridizacije nego inbreedinga, a definitivno je definisan upravo onako kao sam ja napisao, pa provjeri jos jedanput.

Offline piroman

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Re: Ugrozene i nestale vrste
« Reply #31 on: 15 January, 2006, 07:01:59 »
Heterosis
From Wikipedia, the free encyclopedia.

    Heterotic string theory is a field of physics.

Heterosis is increased strength of different characteristics in hybrids; the possibility to obtain a "better" individual by combining the virtues of its parents.


This is commonly known as hybrid vigor or outbreeding enhancement. It is often the opposite process of inbreeding depression, which increases homozygosity. Heterosis is an example of heterozygous advantage. The term often causes controversy, particularly in terms of domestic animals, because it is sometimes believed that all crossbred plants or animals are better than their parents; this is untrue. Rather, when a hybrid is seen to be superior to its parents, this is known as hybrid vigor. It may also happen that a hybrid inherits such different traits from their parents that make them unfit for survival. This is known as outbreeding depression, and usually occurs in breeding between wild fish and hatchery fish that have incompatible adaptations.

Heterosis in humans

One study suggests that hybrid vigor may be associated with increased intelligence in humans. Nagoshi and Johnson (1986) found that children of Japanese-Caucasian cross-ethnic unions scored .26 SD higher on several cognitive tests than those from within-ethnic families, despite having virtually identical parental educational and occupational backgrounds (p. 204). The increase in scores tended to be higher on cognitive tests that were more g-loaded, suggesting that hybrid vigor improves g. To become more reliable, the study would have to match the intelligence averages of the parents as well as compute the intelligence scores of their children. Mingroni (2004) has argued that heterosis may be partially responsible for the Flynn effect.

The Minnesota Transracial Adoption Study shows US children of African-Caucasian cross-ethnic unions score .47 SD lower on cognitive tests taken at age 17 than adopted children of Caucasian heritage, and .67 SD higher than adopted children of African heritage. (The average IQ of the adopting parents in this study was more than 1 standard deviation above the population mean of 100.) The exact interpretation of this study is disputed.



F1 hybrid
From Wikipedia, the free encyclopedia.

F1 hybrids are the first generation seeds/plants or animal offspring resulting from a cross mating of distinctly different parental types, the offspring of which produce a new, uniform variety with specific characteristics from both parents. In fish breeding, those parents frequently are two closely related fish species, while in plant and animal genetics those parents usually are two inbred lines. Mules are F1 hybrids between horse and donkey. Crossing specific parent plants produces a hybrid seed (plant) by means of controlled pollination. To produce consistent F1 hybrids, the original cross must be repeated each season. As in the original cross, in plants this is usually done through controlled hand-pollination, and explains why F1-seeds are so expensive.
In agronomy the term "F1 hybrids" is usually reserved for agricultural cultivars where he parental types are two inbred and thus almost homozygous lines. Because of the almost pure homozygosity of the parent lines, F1 hybrids have a very high level of heterozygosity. As a result of this, F1 hybrids display improved growth and yield characteristics.
In agronomy the term "F1 hybrids" is usually reserved for agricultural cultivars where he parental types are two inbred and thus almost homozygous lines. Because of the almost pure homozygosity of the parent lines, F1 hybrids have a very high level of heterozygosity. As a result of this, F1 hybrids display improved growth and yield characteristics.

Production of F1 hybrids


In plants

Two populations of breeding stock with desired characteristics are subject to inbreeding until the homozygocy of the population exceeds a certain level, usually 90% or more. Typically this requires more than ten generations. After this happens, both populations must be crossed while avoiding self-fertilization. Normally this happens in plants by deactivating or removing male flowers from one population, taking advantage of time differences between male and female flowering or hand-pollinating[1].



In animals

Commonly breeded fish species as well as all mammals and birds are not hermaphrodite, like most plants are, and therefore it is much more easy to prevent self-fertilization during a F1 cross. F1 crosses in fish can be between two inbred lines or between two closely related fish species, like between cichlid subspecies.[2]. The cross usually is performed by natural or artificial insemination.


Advantages

    * Homogenity and predictability - because of the homozygocy of the parent pure lines, there is next to none genetic variation between individual plants or animals. This makes their phenotype extremely uniform and thus attractive for mechanical operations and makes it easier to fine-tune the management of the population. Once the characteristics of the cross are known, repeating this cross will yield exactly the same result.
    * Higher performance - As all not junk DNA alleles codify for a certain version of a protein or enzyme, having two different versions of this allele amounts in having two different versions of the enzyme. This will increase the likelihood of having an optimal version of the enzyme present and reduce the likelihood of a genetic defect. This effect is referred to in genetics as the genetic hysteresis effect.



Disadvantages

    * The main advantage of F1 hybrids is their drawback as well. When F1 cultivars are used for the breeding of a new generation, their offspring will revert to the natural level of heterozygocy and thus will have a depression in yield. Of course, this is a desired characteristic from the point of view of the seed producer.
    * Both inbreeding as well as crossing both lines requires a lot of work, which translates in a much higher seeds cost. In general, the higher yield offsets this disadvantage.




Inbreeding
From Wikipedia, the free encyclopedia.


Inbreeding is breeding between close relatives.

If practised repeatedly, it typically leads to a reduction in genetic diversity. Inbreeding often leads to reduced health and fitness (called consanguinity depression, inbreeding depression); however, livestock breeders often practice inbreeding, then cull unfit offspring, especially when they are trying to establish a new and desirable trait in their stock.

An inbred individual is likely to possess several physical and health defects, in addition to higher incidence of inheriting a poor trait. They include:

    * reduced fertility both in litter size and in sperm viability
    * increased congenital defects
    * fluctuating facial asymmetry
    * lower birth rate
    * higher neo-natal mortality
    * slower growth rate
    * smaller adult size
    * loss of immune system function.


Means to avoid inbreeding

Mammals, most other animals, and higher plants as well, have ways to minimize inbreeding. They can be mechanical or societal.

An example of mechanical means is the sweet cherry. It has an elaborate biochemical mechanism that precludes self-fertilisation and combination of gametes of high genetical similarity. Fruit flies, on the other hand, have a sensing mechanism to do the same thing, and more genetic diversity than expected by random mating is observed even in a closed population.

The incest taboo in humans is a societal means to avoid inbreeding. Mating with close relatives is often forbidden, although the definition of "close relatives" varies - it can include immediate family (parents, siblings), extended family (cousins) or even exclude whole generations (anyone of your father/mother's generation). Many pack or herd animals (such as lions, horses and dogs) inadvertently practice a social method to reduce inbreeding: young males are expelled from the group before they reach sexual maturity and might become competition for the alpha male, the only one to have sexual rights within his group.

The cheetah is a highly inbred species, probably because of a population bottleneck in the species' recent past. Inbreeding is also deliberately induced in laboratory mice in order to guarantee a consistent and uniform animal model. Human genetic diversity is also limited, indicating a population bottleneck perhaps some 70,000 years ago.

Purebred animals are often inbred; some critics argue the practice is unhealthy.

Where a species is threatened by extinction, the population may fall below a minimum whereby the forced interbreeding between the remaining animals will result in extinction.


Inbred humans

Royalty

The royal families of Europe have close blood ties which are strengthened by intermarriage; the most discussed instances of interbreeding relate to European monarchies. Examples abound in every royal family; in particular, the ruling dynasties of Spain and Portugal were very inbred. Even in the British royal family, which is very moderate in comparison, there has scarcely been a monarch in 300 years who has not married a (near or distant) relative. Indeed, Queen Elizabeth II and her husband Prince Philip are second cousins once removed, both being descended from Christian IX of Denmark. They are also third cousins as great-great-grandchildren of Queen Victoria. Other examples include:

    * Mary, Queen of Scots and Henry Stuart, Lord Darnley were half first cousins, and 3rd cousins once removed
    * King William III and Queen Mary II were first cousins
    * King George I and Princess Sophia Dorothea of Celle were paternal first cousins
    * King George IV and Princess Caroline of Brunswick were first cousins
    * Queen Victoria and Prince Albert of Saxe-Coburg-Gotha were first cousins
    * King George V and Princess Mary of Teck were second cousins once removed
    * The House of Habsburg intermarried famously
    * Many Egyptian Pharaohs married their sisters

However, it is not necessarily the case that there is a greater amount of inbreeding within royalty than there is in the population as a whole: it is simply better documented. Among genetic populations that are isolated, opportunities for exogamy are reduced. Isolation may be geographical, leading to inbreeding among peasants in remote mountain valleys. Or isolation may be social, induced by the lack of appropriate partners, such as Protestant princesses for Protestant royal heirs. Since the late middle ages, it is the urban middle class that has had the widest opportunity for outbreeding.


The Rothschilds

Among the descendants of Mayer Amschel Rothschild, the founder of the famous financial and banking family, many of the men married their brothers's daughters or cousins related through the male line, neither if which practices is forbidden by Jewish law. They also had the tradition that only male descendants in the male line could participate in the business, though daughters did inherit considerable wealth. These two traditions were a means of keeping the business closely in the family, for purposes of secrecy. This was the reason that, in 1901, the Frankfurt branch of the family business was closed when the male line, that managed it, died out.

Zivela nam www.wikipedia.org
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Piroman



Offline saulosi

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Re: Ugrozene i nestale vrste
« Reply #32 on: 15 January, 2006, 11:10:25 »
Piromane svaka cast for the effort

Ono sto mene zanima je , jesi li ti procitao sve ovo?
Moja greska je bila u tome sto sam napisao da se heterozis desava kod inbreedinga i jos jednom se izvinjavam.Pokazalo se da je ovakve stvari najbolje pisati u trezvenom stanju i nikako u sitne sate

Offline aleks667

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Re: Ugrozene i nestale vrste
« Reply #33 on: 15 January, 2006, 15:29:14 »
Ne znam za Piromana, ali ja NISAM procitao ono. Izvinite sto sam uopste pokrenuo temu :)

Offline piroman

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Re: Ugrozene i nestale vrste
« Reply #34 on: 16 January, 2006, 05:24:58 »
Jesam Saulosi, procitao sam, i zakljucio sam da je trebalo da studiram biologiju :(

Aleks, koji ti je??? Sto se izvinjavas??? Tema je tema, i sukobi misljenja su ono sto donosi znanje i napredak! Ja sam se "svadjao" mnogo puta na ovom sajtu oko mnogih stvari, i mislim da su mnogi imali samo korist od mojih "svadja" !!!
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Piroman



Offline aleks667

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Re: Ugrozene i nestale vrste
« Reply #35 on: 16 January, 2006, 08:20:18 »
Smajli, vidis smajli. Izgleda da cu morati da stavljam one zute. Zezao sam diskusija je put do znanja  CIKLID_111

Offline piroman

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Re: Ugrozene i nestale vrste
« Reply #36 on: 16 January, 2006, 09:31:28 »
Sorry Aleks, my bad!
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Offline saulosi

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Re: Ugrozene i nestale vrste
« Reply #37 on: 30 July, 2006, 02:21:57 »
Spisak ugroyenih sa IUCN crvene liste po reviziji iz 2000 godine:

Astatotilapia       Status and Location
Astatotilapia "dwarf bigeye scraper"    Critically Endangered  in Lake Kanyaboli
Astatotilapia "shovelmouth"    Endangered in Lake kyoga, Lake Nawampasa
Astatotilapia barbarae    Endangered in Lake Nawampasa, Lake Victoria, and Victoria Nile
Astatotilapia brownae     Endangered in Lake Victoria
Astatotilapia latifasciata     Critically Endangered in Lake Nawampasa
Astatotilapia martini    Extinct status is being re-evaluated
Astatotilapia megalops    Extinct status is being re-evaluated
Astatotilapia piceata    Endangered in Lake Victoria
Astatotilapia velifer      Vulnerable in Nabugabo Lakes
Enterochromis    
Enterochromis paropius    Critically Endangered in Lake Victoria
Haplochromis    
Haplochromis "ruby"    Critically Endangered in Lake Nawampasa
Haplochromis annectidens    Critically Endangered in Nabugabo
Haplochromis lividus       Extinct in the Wild
Haplochromis obliquidens    Endangered in Lake Bunyoni, Lake Victoria
Harpagochromis    
Harpagochromis "frogmouth"        Vulnerable in Lake Victoria
Harpagochromis artaxerxes    Extinct status is being re-evaluated
Harpagochromis boops     Extinct status is being re-evaluated
Harpagochromis cavifrons    Extinct status is being re-evaluated
Harpagochromis guiarti ssp. complex    Critically Endangered in Lake Victoria
Harpagochromis maculipinna      Extinct status is being re-evaluated
Harpagochromis michaeli      Extinct status is being re-evaluated
Harpagochromis nyanzae    Extinct status is being re-evaluated
Harpagochromis pachycephalus    Extinct status is being re-evaluated
Harpagochromis paraplagiostoma    Extinct status is being re-evaluated
Harpagochromis pectoralis     Extinct status is being re-evaluated
Harpagochromis plagiostoma     Critically Endangered in Lake Victoria
Harpagochromis spekii    Extinct status is being re-evaluated
Harpagochromis thuragnathus      Extinct status is being re-evaluated
Harpagochromis victorianus     Extinct status is being re-evaluated
Harpagochromis worthingtoni     Critically Endangered in Lake Nawampasa
Hoplotilapia    
Hoplotilapia retrodens    Extinct status is being re-evaluated
Labrochromis    
Labrochromis ishmaeli    Extinct in the Wild in Lake Victoria
Labrochromis mylergates    Extinct status is being re-evaluated
Labrochromis pharyngomylus    Extinct status is being re-evaluated
Labrochromis teegelaari      Extinct status is being re-evaluated
Lipochromis    
Lipochromis "backflash cryptodon"    Critically Endangered  in Lake Nawampasa
Lipochromis "black cryptodon"    Critically Endangered  in Lake Victoria but is believed to be extinct
Lipochromis "parvidens - like"    Critically Endangered in Lake Nawampasa
Lipochromis "small obesoid"    Critically Endangered in Lake Nawampasa
Lipochromis maxillaris    Critically Endangered in Lake Kanyaboli
Lipochromis melanopterus ssp. complex    Critically Endangered in Lake Victoria
Lipochromis microdon    Extinct status is being re-evaluated
Macropleurodus    
Macropleurodus bicolor     Critically Endangered in Lake Victoria
Paralabidochromis    
Paralabidochromis beadle    Critically Endangered in Lake Nabugabo
Paralabidochromis chilotes ssp. complex    Vulnerable in Lake Victoria
Paralabidochromis chromogynos     Vulnerable in Lake Victoria
Paralabidochromis crassilabris    Vulnerable in Lake Victoria
Paralabidochromis victoriae     Critically Endangered in Lake Victoria
Platyaeniodus    
Platytaeniodus degeni    Extinct in the Wild
Prognathochromis    
Prognathochromis "long snout"    Endangered in Lake Kyoga, Lake Nawampasa
Prognathochromis arcanus     Extinct status is being re-evaluated
Prognathochromis argenteus    Extinct status is being re-evaluated
Prognathochromis bartoni     Extinct status is being re-evaluated
Prognathochromis bayoni    Extinct status is being re-evaluated
Prognathochromis decticostoma    Extinct status is being re-evaluated
Prognathochromis dentex    Extinct status is being re-evaluated
Prognathochromis estor     Extinct status is being re-evaluated
Prognathochromis flavipinnis    Extinct status is being re-evaluated
Prognathochromis gilberti    Extinct status is being re-evaluated
Prognathochromis gowersi     Extinct status is being re-evaluated
Prognathochromis howesi ssp. complex    Endangered in Lake Victoria
Prognathochromis longirostris    Extinct status is being re-evaluated
Prognathochromis macrognathus    Extinct status is being re-evaluated
Prognathochromis mandibularis    Extinct status is being re-evaluated
Prognathochromis mento    Critically Endangered in Lake Victoria
Prognathochromis nanoserranus    Extinct status is being re-evaluated
Prognathochromis nigrescens    Extinct status is being re-evaluated
Prognathochromis paraguiarti     Extinct status is being re-evaluated
Prognathochromis percoides    Extinct status is being re-evaluated
Prognathochromis perrieri    Extinct in the Wild in Lake Victoria
Prognathochromis prognathus    Extinct status is being re-evaluated
Prognathochromis pseudopellegrini    Extinct status is being re-evaluated
Prognathochromis venator    Endangered in Nabugabo Lakes
Prognathochromis vittatus     Extinct status is being re-evaluated
Prognathochromis worthingtoni    Critically Endangered in Lake Nawampasa
Prognathochromis xenostoma    Extinct status is being re-evaluated
Psammochromis    
Psammochromis acidens     Vulnerable in Lake Victoria
Psammochromis aelocephalus     Vulnerable in Lake Victoria
Psammochromis cassius    Extinct status is being re-evaluated
Ptyochromis    
Ptyochromis"Rusinga oral sheller"    Critically Endangered in Lake Victoria
Ptyochromis "rainbow sheller"    Critically Endangered in Lake Victoria
Ptyochromis annectens    Endangered in Lake Victoria
Ptyochromis granti    Endangered in Lake Victoria
Ptyochromis sauvagei     Vulnerable in Lake Victoria
Pyxichromis    
Pyxichromis orthostoma    Vulnerable in Lake Kyoga, Lake Nawampasa
Pyxichromis parorthostoma    Extinct status is being re-evaluated
Xystichromis    
Xystichromis "Kyoga flameback"    Critically Endangered in Lake Nawampasa
Xystichromis bayoni    Extinction not questioned
Xystichromis nuchisquamulatus    Endangered in Lake Victoria
Xystichromis phytophagus    Critically Endangered in Lake Kanyaboli
Yssichromis    
Yssichromis argens    Extinct in the Wild in Lake Victoria
Yssichromis pyrrhocephalus    Vulnerable in Lake Victoria
Other Endangered Fish in the Area    
Oreochromis esculentus    Vulnerable
Oreochromis variabilis    Vulnerable  in Lake Nawampasa, Lake Victoria

Offline saulosi

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Re: Ugrozene i nestale vrste
« Reply #38 on: 30 July, 2006, 02:24:09 »
Izvinjavam se zbog nepreglednosti ali  nisam mogao da ukljuchim ni italic ni bold opciju.

Offline ducia

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Re: Ugrozene i nestale vrste
« Reply #39 on: 30 July, 2006, 21:25:48 »
E, a koje od ugrozenih vrsta mogu da se nadju u Srbiji, tj. u Srpskim AQ?
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