automixis การใช้

• The details vary, but at least some species can reproduce automixis.
• Some authors consider all forms of automixis sexual as they involve recombination.
• The WW females are likely produced by terminal automixis.
• Automixis with central fusion tends to maintain heterozygosity in the passage of the genome from mother to daughter.
• Automixis with terminal fusion tends to promote homozygosity in the passage of the genome from mother to daughter.
• Automixis appears to involve central fusion of two of the haploid products of meiosis ( see diagram ).
• Those cases of automixis that are classified as sexual reproduction are compared to self-fertilization in their mechanism and consequences.
• Oocytes that undergo automixis with central fusion often have a reduced rate of crossover recombination, which helps to maintain heterozygosity and avoid inbreeding depression.
• Oocytes that undergo automixis with central fusion often display a reduced rate of heterozygosity, and only a slow transition from heterozygosity to homozygosity over successive generations.
• Among these authors the threshold for classifying automixis as a sexual process depends on when the products of anaphase I or of anaphase II are joined together.
• This form of automixis tends to maintain crossover recombination occurs at a greatly reduced rate during meiosis, which likely restrains the transition from heterozygosity to homozygosity.
• This form of automixis has been observed in the water flea " Daphnia magna " and the Colombian rainbow boa constrictor " Epicrates maurus ".
• The form of thelytoky in hymenopterans is a kind of automixis in which two haploid products ( proto-eggs ) from the same meiosis fuse to form a diploid zygote.
• However, survival of offspring over two successive litters was poor, suggesting that automixis with terminal fusion leads to homozygosity and expression of deleterious recessive alleles ( inbreeding depression ).
• The oocytes that undergo automixis display much lower rates of crossover recombination ( by a factor of 45 ) than the oocytes produced by sexually reproducing queens that give rise to workers.
• The type of parthenogenesis that likely occurs is automixis with terminal fusion ( see figure ), a process in which two terminal products from the same meiosis fuse to form a diploid zygote.
• When clonally aged " P . tetraurelia " are stimulated to undergo meiosis in association with either conjugation or automixis, the progeny are rejuvenated, and are able to have many more mitotic binary fission divisions.
• The sharp decrease in recombination rates likely allows clonal queens using automixis to benefit from thelytoky ( transmission of their entire genomes to individual progeny ), while also avoiding the potential for inbreeding depression that would result from random fusion of meiotic products leading to loss of heterozygosity.
• This form of automixis has been observed in several ant species including the desert ant " Cataglyphis cursor ", the predaceous ant " Platythyrea punctata ", Automixis with central fusion also occurs in the Cape honey bee " Apis mellifera capensis ", the brine shrimp " Artemia parthenogenetica ", and the termite " Embiratermes neotenicus ".
• This form of automixis has been observed in several ant species including the desert ant " Cataglyphis cursor ", the predaceous ant " Platythyrea punctata ", Automixis with central fusion also occurs in the Cape honey bee " Apis mellifera capensis ", the brine shrimp " Artemia parthenogenetica ", and the termite " Embiratermes neotenicus ".