Crespo-López María E, Duarte Tiago, Dowling Thomas, Coelho Maria M
Centro de Biologia Ambiental/Departamento de Biologia Animal, Faculdade de Ciências da Universidade de Lisboa, Bloco C2-3 piso, Campo Grande, 1749-016 Lisbon, Portugal.
Zoology (Jena). 2006;109(4):277-86. doi: 10.1016/j.zool.2006.03.008. Epub 2006 Sep 20.
The Squalius alburnoides complex was produced by hybridization between female S. pyrenaicus (PP genome) and an hypothetical paternal ancestor related with Anaecypris hispanica (AA genome). This study examined a diversity of mating types and found that there is the potential for considerable gene exchange among diploid, triploid and tetraploid hybrids. Using microsatellites, genomes were attributed to Squalius pyrenaicus (P) or reconstituted "nuclear non-hybrid"S. alburnoides (A), and subsequently confirmed in hybrids. Recombination of AA genomes in the "nuclear non-hybrid males" and recombination of the homogametic genomes (AA or PP) after exclusion of the heterogametic genome in triploid females (PAA) were observed by analysing parents and progeny of breeding experiments. Reproduction of tetraploids, generating a symmetric tetraploid genotype (PPAA) in the progeny, suggests a process that could potentially lead to the formation of a new bisexual species. Present results also support: (i) previously hypothesized pathways, in which PPA S. alburnoides females exclude the A genome, exhibit meiotic recombination between the P genomes and generate haploid eggs; (ii) reconstitution of the diploid maternal ancestor genome (PP) as well as of the unknown paternal ancestor (AA); (iii) the occurrence of the same genomic reproductive mechanisms when Anaecypris hispanica is involved; and (iv) the existence of an A. hispanica-like ancestor as the paternal ancestor of S. alburnoides.
拟鲤复合种是由雌性比利牛斯拟鲤（PP基因组）与一个与西班牙无齿鲱（AA基因组）相关的假定父本祖先杂交产生的。本研究考察了多种交配类型，发现二倍体、三倍体和四倍体杂种之间存在大量基因交换的可能性。利用微卫星，将基因组归为比利牛斯拟鲤（P）或重构的“核非杂种”拟鲤（A），随后在杂种中得到证实。通过分析育种实验的亲本和后代，观察到“核非杂种雄性”中AA基因组的重组以及三倍体雌性（PAA）中异型配子基因组被排除后同型配子基因组（AA或PP）的重组。四倍体的繁殖在后代中产生对称的四倍体基因型（PPAA），这表明该过程可能潜在地导致一个新的两性物种的形成。目前的结果还支持：（i）先前假设的途径，即PPA拟鲤雌性排除A基因组，在P基因组之间表现出减数分裂重组并产生单倍体卵子；（ii）二倍体母本祖先基因组（PP）以及未知父本祖先（AA）的重构；（iii）当涉及西班牙无齿鲱时相同基因组生殖机制的发生；以及（iv）存在一个类似西班牙无齿鲱的祖先作为拟鲤的父本祖先。
