Nokkala Seppo, Kuznetsova Valentina G, Nokkala Christina
Laboratory of Genetics, Department of Biology, University of Turku, FI-20014, Turku, Finland.
Department of Karyosystematics, Zoological Institute, Russian Academy of Sciences, St. Petersburg 199034, Russia.
Comp Cytogenet. 2017 Nov 24;11(4):807-817. doi: 10.3897/CompCytogen.v11i4.21362. eCollection 2017.
Characteristics of parthenogenesis in (Flor, 1861) were analyzed using cytological and molecular approaches. In all three populations studied from Finland, i.e. Turku, Kustavi and Siikajoki, males were present at a low frequency but were absent from a population from Vorkuta, Russia. In a follow-up study conducted in the Turku population during 2010-2016, the initial frequency of males was ca. 10 % and showed no intraseasonal variation, but then dramatically decreased down to approximately 1-2 % level in seasons 2015-2016. Male meiosis was chiasmate with some traces of chromosomal fragmentation and subsequent fusions. In most females, metaphase in mature eggs included 39 univalent chromosomes which indicated apomictic triploidy. Only a small fraction of females was diploid with 13 chiasmate bivalents. The frequency of diploid females approximately equaled that of males. barcode analyses showed that triploid females (N = 57) and diploids (7 females and 5 males) displayed different haplotypes, demonstrating that triploid females reproduced via obligate parthenogenesis. The rarity of diploids, along with the lack of males' preference towards diploid females, suggested that most likely diploids were produced by rare triploid females which shared the same haplotype with the diploids (not found in the present analysis). Minimum haplotype diversity was detected in the Turku population, but it was much higher in Vorkuta with some indication for the mixed origin of the population. We suggest that functional diploids produced in a parthenogenetic population can give rise either to a new parthenogenetic lineage or even to a new bisexual species.
利用细胞学和分子方法分析了（弗洛尔，1861年）孤雌生殖的特征。在从芬兰研究的所有三个种群中，即图尔库、库斯塔维和尚卡约基，雄性个体出现频率较低，但在俄罗斯沃尔库塔的一个种群中未发现雄性。在2010 - 2016年对图尔库种群进行的后续研究中，雄性的初始频率约为10%，且季节内无变化，但在2015 - 2016年季节中急剧下降至约1 - 2%的水平。雄性减数分裂有交叉现象，并伴有一些染色体片段化和随后融合的痕迹。在大多数雌性中，成熟卵的中期包含39条单价染色体，这表明是无融合生殖三倍体。只有一小部分雌性是二倍体，有13个交叉二价体。二倍体雌性的频率与雄性大致相等。条形码分析表明，三倍体雌性（N = 57）和二倍体（7只雌性和5只雄性）表现出不同的单倍型，表明三倍体雌性通过专性孤雌生殖进行繁殖。二倍体的稀少，以及雄性对二倍体雌性没有偏好，表明很可能二倍体是由与二倍体共享相同单倍型的罕见三倍体雌性产生的（在本分析中未发现）。在图尔库种群中检测到最小的单倍型多样性，但在沃尔库塔要高得多，这表明该种群有混合起源。我们认为，孤雌生殖种群中产生的功能性二倍体可以产生一个新的孤雌生殖谱系，甚至可能产生一个新的两性物种。
