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101.
C. Rosche K. Schrieber S. Lachmuth W. Durka H. Hirsch V. Wagner M. Schleuning I. Hensen 《Plant biology (Stuttgart, Germany)》2018,20(4):789-796
- Habitat fragmentation and small population size can lead to genetic erosion in threatened plant populations. Classical theory implies that dioecy can counteract genetic erosion as it decreases the magnitude of inbreeding and genetic drift due to obligate outcrossing. However, in small populations, sex ratios may be strongly male‐ or female‐biased, leading to substantial reductions in effective population size. This may theoretically result in a unimodal relationship between sex ratios and genetic diversity; yet, empirical studies on this relationship are scarce.
- Using AFLP markers, we studied genetic diversity, structure and differentiation in 14 highly fragmented Antennaria dioica populations from the Central European lowlands. Our analyses focused on the relationship between sex ratio, population size and genetic diversity.
- Although most populations were small (mean: 35.5 patches), genetic diversity was moderately high. We found evidence for isolation‐by‐distance, but overall differentiation of the populations was rather weak. Females dominated 11 populations, which overall resulted in a slightly female‐biased sex ratio (61.5%). There was no significant relationship between population size and genetic diversity. The proportion of females was not unimodally but positively linearly related to genetic diversity.
- The high genetic diversity and low genetic differentiation suggest that A. dioica has been widely distributed in the Central European lowlands in the past, while fragmentation occurred only in the last decades. Sex ratio has more immediate consequences on genetic diversity than population size. An increasing proportion of females can increase genetic diversity in dioecious plants, probably due to a higher amount of sexual reproduction.
102.
Local pre‐adaptation to disturbance and inbreeding–environment interactions affect colonisation abilities of diploid and tetraploid Centaurea stoebe 下载免费PDF全文
- Primary colonisation in invasive ranges most commonly occurs in disturbed habitats, where anthropogenic disturbance may cause physical damage to plants. The tolerance to such damage may differ between cytotypes and among populations as a result of differing population histories (adaptive differentiation between ruderal verus natural habitats). Moreover, founder populations often experience inbreeding depression, the effects of which may increase through physical damage due to inbreeding–environment interactions. We aimed to understand how such colonisation processes differ between diploid and tetraploid Centaurea stoebe populations, with a view to understanding why only tetraploids are invasive.
- We conducted a clipping experiment (frequency: zero, once or twice in the growing season) on inbred versus outbred offspring originating from 37 C. stoebe populations of varying cytotype, range and habitat type (natural versus ruderal). Aboveground biomass was harvested at the end of the vegetation period, while re‐sprouting success was recorded in the following spring.
- Clipping reduced re‐sprouting success and biomass, which was significantly more pronounced in natural than in ruderal populations. Inbreeding depression was not detected under benign conditions, but became increasingly apparent in biomass when plants were clipped. The effects of clipping and inbreeding did not differ between cytotypes.
- Adaptive differentiation in disturbance tolerance was higher among populations than between cytotypes, which highlights the potential of pre‐adaptation in ruderal populations during early colonisation on anthropogenically disturbed sites. While the consequences of inbreeding increased through clipping‐mediated stress, they were comparable between cytotypes, and consequently do not contribute to understanding the cytotype shift in the invasive range.
103.
A molecular and evolutionary study of the beta-globin gene family of the Australian marsupial Sminthopsis crassicaudata 总被引:1,自引:0,他引:1
Cooper SJ; Murphy R; Dolman G; Hussey D; Hope RM 《Molecular biology and evolution》1996,13(7):1012-1022
Beta-globin gene families in eutherians (placental mammals) consist of a
set of four or more developmentally regulated genes which are closely
linked and, in general, arranged in the order 5'-embryonic/fetal genes-
adult genes-3'. This cluster of genes is proposed to have arisen by tandem
duplication of ancestral beta-globin genes, with the first duplication
occurring 200 to 155 MYBP just prior to a period in mammalian evolution
when eutherians and marsupials diverged from a common ancestor. In this
paper we trace the evolutionary history of the beta-globin gene family back
to the origins of these mammals by molecular characterization of the
beta-globin gene family of the Australian marsupial Sminthopsis
crassicaudata. Using Southern and restriction analysis of total genomic DNA
and bacteriophage clones of beta-like globin genes, we provide evidence
that just two functional beta-like globin genes exist in this marsupial,
including one embryonic- expressed gene (S.c-epsilon) and one
adult-expressed gene (S.c-beta), linked in the order 5'-epsilon-beta-3'.
The entire DNA sequence of the adult beta-globin gene is reported and shown
to be orthologous to the adult beta-globin genes of the North American
marsupial Didelphis virginiana and eutherian mammals. These results,
together with results from a phylogenetic analysis of mammalian beta-like
globin genes, confirm the hypothesis that a two-gene cluster, containing an
embryonic- and an adult-expressed beta-like globin gene, existed in the
most recent common ancester of marsupials and eutherians. Northern analysis
of total RNA isolated from embryos and neonatals indicates that a switch
from embryonic to adult gene expression occurs at the time of birth,
coinciding with the transfer of the marsupial from a uterus to a pouch
environment.
相似文献
104.
Mohammad?Abass?AhangerEmail author Megha?Tittal Rayees?Ahmad?Mir RM?Agarwal 《Protoplasma》2017,254(5):1953-1963
Present communication reports laboratory and pot experiments conducted to study the influence of water and osmotic stress on nitrogen uptake and metabolism in two wheat (Triticum aestivum L) cultivars with and without potassium supplementation. Polyethylene glycol 6000-induced osmotic stress/restricted irrigation caused a considerable decline in the activity of nitrate reductase, glutamate synthase, alanine and aspartate aminotransferases, and glutamate dehydrogenase. Potassium considerably improved nitrogen metabolism under normal water supply conditions and also resulted in amelioration of the negative impact of water and osmotic stresses indicating that potassium supplementation can be used as a potential tool for enhancing the nitrogen use efficiency in wheat for exploiting its genetic potential. 相似文献
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108.
One of the limitations of the use of phage antibody libraries in high throughput selections is the production of sufficient phage antibody library at the appropriate quality. Here, we successfully adapt a bioreactor-based protocol for the production of phage peptide libraries to the production of phage antibody libraries. The titers obtained in the stirred-tank bioreactor are 4 to 5 times higher than in a standard shake flask procedure, and the quality of the phage antibody library produced is indistinguishable to that produced using standard procedures as assessed by Western blotting and functional selections. Availability of this protocol will facilitate the use of phage antibody libraries in high-throughput scale selections. 相似文献
109.
D Deprez J Fransen M Lenoir RM Philippaerts R Vaeyens 《Biology of sport / Institute of Sport》2015,32(1):65-70
The aim of the study was to investigate test reliability of the Yo-Yo intermittent recovery test level 1 (YYIR1) in 36 high-level youth soccer players, aged between 13 and 18 years. Players were divided into three age groups (U15, U17 and U19) and completed three YYIR1 in three consecutive weeks. Pairwise comparisons were used to investigate test reliability (for distances and heart rate responses) using technical error (TE), coefficient of variation (CV), intra-class correlation (ICC) and limits of agreement (LOA) with Bland-Altman plots. The mean YYIR1 distances for the U15, U17 and U19 groups were 2024 ± 470 m, 2404 ± 347 m and 2547 ± 337 m, respectively. The results revealed that the TEs varied between 74 and 172 m, CVs between 3.0 and 7.5%, and ICCs between 0.87 and 0.95 across all age groups for the YYIR1 distance. For heart rate responses, the TEs varied between 1 and 6 bpm, CVs between 0.7 and 4.8%, and ICCs between 0.73 and 0.97. The small ratio LOA revealed that any two YYIR1 performances in one week will not differ by more than 9 to 28% due to measurement error. In summary, the YYIR1 performance and the physiological responses have proven to be highly reliable in a sample of Belgian high-level youth soccer players, aged between 13 and 18 years. The demonstrated high level of intermittent endurance capacity in all age groups may be used for comparison of other prospective young soccer players. 相似文献
110.
Kjellman BM Fredrikson M Glad-Mattsson G Sjöberg F Huss FR 《Annals of surgical innovation and research》2011,5(1):4-8