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Abstract：
Despite the recent wealth of studies targeted at contact zones of cytotypes in various species, some aspects of polyploid evolution are still poorly understood. This is especially the case for the frequency and success rate of spontaneous neopolyploidization or the temporal dynamics of ploidy coexistence, requiring massive ploidy screening and repeated observations, respectively. To fill this gap, an extensive study of spatio-temporal patterns of ploidy coexistence was initiated in the widespread annual weed Tripleurospermum inodorum (Asteraceae).
DNA flow cytometry along with confirmatory chromosome counts was employed to assess ploidy levels of 11 018 adult individuals and 1263 ex situ germinated seedlings from 1209 Central European populations. The ploidy screening was conducted across three spatial scales and supplemented with observations of temporal development of 37 mixed-ploidy populations.
The contact zone between the diploid and tetraploid cytotypes has a diffuse, mosaic-like structure enabling common cytotype coexistence from the within-population to the landscape level. A marked difference in monoploid genome size between the two cytotypes enabled the easy distinction of neotetraploid mutants from long-established tetraploids. Neotetraploids were extremely rare (0·03 %) and occurred solitarily. Altogether five ploidy levels (2 x -6 x ) and several aneuploids were discovered; the diversity in nuclear DNA content was highest in early ontogenetic stages (seedlings) and among individuals from mixed-ploidy populations. In spite of profound temporal oscillations in cytotype frequencies in mixed-ploidy populations, both diploids and tetraploids usually persisted up to the last census.
Diploids and tetraploids commonly coexist at all spatial scales and exhibit considerable temporal stability in local ploidy mixtures. Mixed-ploidy populations containing fertile triploid hybrids probaby act as effective generators of cytogenetic novelty and may facilitate inter-ploidy gene flow. Neopolyploid mutants were incapable of local establishment.
DNA flow cytometry along with confirmatory chromosome counts was employed to assess ploidy levels of 11 018 adult individuals and 1263 ex situ germinated seedlings from 1209 Central European populations. The ploidy screening was conducted across three spatial scales and supplemented with observations of temporal development of 37 mixed-ploidy populations.
The contact zone between the diploid and tetraploid cytotypes has a diffuse, mosaic-like structure enabling common cytotype coexistence from the within-population to the landscape level. A marked difference in monoploid genome size between the two cytotypes enabled the easy distinction of neotetraploid mutants from long-established tetraploids. Neotetraploids were extremely rare (0·03 %) and occurred solitarily. Altogether five ploidy levels (2 x -6 x ) and several aneuploids were discovered; the diversity in nuclear DNA content was highest in early ontogenetic stages (seedlings) and among individuals from mixed-ploidy populations. In spite of profound temporal oscillations in cytotype frequencies in mixed-ploidy populations, both diploids and tetraploids usually persisted up to the last census.
Diploids and tetraploids commonly coexist at all spatial scales and exhibit considerable temporal stability in local ploidy mixtures. Mixed-ploidy populations containing fertile triploid hybrids probaby act as effective generators of cytogenetic novelty and may facilitate inter-ploidy gene flow. Neopolyploid mutants were incapable of local establishment.
摘要：
尽管最近针对各种物种的细胞类型接触区进行了大量研究，多倍体进化的某些方面仍然知之甚少。对于自发的新多倍体化的频率和成功率或倍性共存的时间动力学尤其如此，需要大量倍性筛选和重复观察，分别。为了填补这个空白，在广泛的一年生杂草Tripleurospermuminodorum（菊科）中，对倍性共存的时空模式进行了广泛的研究。
使用DNA流式细胞术和确认染色体计数来评估来自1209个中欧种群的11018个成年个体和1263个异位发芽幼苗的倍性水平。倍性筛选在三个空间尺度上进行，并辅以对37个混合倍性种群的时间发展的观察。
二倍体和四倍体细胞类型之间的接触区具有弥漫性，马赛克状结构，可实现从人口内部到景观级别的常见细胞类型共存。两种细胞类型之间单倍体基因组大小的显着差异使得新四倍体突变体与长期建立的四倍体容易区分。新四倍体极为罕见（0·03％），并单独出现。总共发现了五个倍性水平（2x-6x）和几个非整倍体；在个体发育早期（幼苗）和来自混合倍性种群的个体中，核DNA含量的多样性最高。尽管混合倍性种群的细胞型频率发生了深刻的时间振荡，二倍体和四倍体通常持续到最后一次人口普查。
二倍体和四倍体通常在所有空间尺度上共存，并且在局部倍性混合物中表现出相当大的时间稳定性。含有可育三倍体杂种的混合倍性种群可能是细胞遗传学新颖性的有效产生者，并可能促进倍性基因流。新多倍体突变体无法在本地建立。
使用DNA流式细胞术和确认染色体计数来评估来自1209个中欧种群的11018个成年个体和1263个异位发芽幼苗的倍性水平。倍性筛选在三个空间尺度上进行，并辅以对37个混合倍性种群的时间发展的观察。
二倍体和四倍体细胞类型之间的接触区具有弥漫性，马赛克状结构，可实现从人口内部到景观级别的常见细胞类型共存。两种细胞类型之间单倍体基因组大小的显着差异使得新四倍体突变体与长期建立的四倍体容易区分。新四倍体极为罕见（0·03％），并单独出现。总共发现了五个倍性水平（2x-6x）和几个非整倍体；在个体发育早期（幼苗）和来自混合倍性种群的个体中，核DNA含量的多样性最高。尽管混合倍性种群的细胞型频率发生了深刻的时间振荡，二倍体和四倍体通常持续到最后一次人口普查。
二倍体和四倍体通常在所有空间尺度上共存，并且在局部倍性混合物中表现出相当大的时间稳定性。含有可育三倍体杂种的混合倍性种群可能是细胞遗传学新颖性的有效产生者，并可能促进倍性基因流。新多倍体突变体无法在本地建立。
