scholarly journals The influence of environmental factors, the pollen : ovule ratio and seed bank persistence on molecular evolutionary rates in plants

2006 ◽  
Vol 19 (1) ◽  
pp. 302-308 ◽  
Author(s):  
C.-A. WHITTLE
Keyword(s):  
Environmental Factors ◽  
Seed Bank ◽  
Evolutionary Rates ◽  
Molecular Evolutionary Rates

scholarly journals Rainfall in growing season determines the size of an annual-dominated soil seed bank in a desert ecosystem

2020 ◽  
Author(s):  
Ya-Fei Shi ◽  
Zengru Wang ◽  
Bing-Xin Xu ◽  
Jian-Qiang Huo ◽  
Rui Hu ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Species Composition ◽  
Seed Bank ◽  
Soil Seed Bank ◽  
Growing Season ◽  
Seed Banks ◽  
Desert Ecosystem ◽  
Perennial Herb ◽  
Desert Ecosystems ◽  
Soil Seed Banks

Soil seed banks may offer great potential for restoring and maintaining desert ecosystems that have been degraded by climate change and anthropogenic disturbance. However, few studies have explored the annual dynamics in the composition and relative abundance of these soil seed banks. We conducted a long-term observational study to assess the effects of environmental factors (meteorology and microtopography) and aboveground vegetation on the soil seed bank of the Tengger Desert, China. The desert seed bank was dominated by annual herbs. We found that more rainfall in the growing season increased the number of seeds in the soil seed bank, and that quadrats at relatively higher elevations had fewer seeds. The species composition had more similarity in the seed bank than in the aboveground vegetation, though the seed bank and aboveground vegetation did change synchronously due to the rapid propagation of annuals. Together, our findings suggest that the combined effects of environmental factors and plant life forms determine the species composition and size of soil seed banks in deserts. Thus, if degraded desert ecosystems are left to regenerate naturally, the lack of shrub and perennial herb seeds could crucially limit their restoration. Human intervention and management may have to be applied to enhance the seed abundance of longer-lived lifeforms in degraded deserts.

scholarly journals Evolutionary rates of mitochondrial genomes correspond to diversification rates and to contemporary species richness in birds and reptiles

2010 ◽  
Vol 277 (1700) ◽  
pp. 3587-3592 ◽  
Author(s):  
Soo Hyung Eo ◽  
J. Andrew DeWoody
Keyword(s):  
Species Richness ◽  
Nuclear Data ◽  
Synonymous Substitution ◽  
Evolutionary Rates ◽  
Rate Variation ◽  
Substitution Rates ◽  
Diversification Rates ◽  
Extinction Process ◽  
Molecular Evolutionary Rates ◽  
Speciation Rates

Rates of biological diversification should ultimately correspond to rates of genome evolution. Recent studies have compared diversification rates with phylogenetic branch lengths, but incomplete phylogenies hamper such analyses for many taxa. Herein, we use pairwise comparisons of confamilial sauropsid (bird and reptile) mitochondrial DNA (mtDNA) genome sequences to estimate substitution rates. These molecular evolutionary rates are considered in light of the age and species richness of each taxonomic family, using a random-walk speciation–extinction process to estimate rates of diversification. We find the molecular clock ticks at disparate rates in different families and at different genes. For example, evolutionary rates are relatively fast in snakes and lizards, intermediate in crocodilians and slow in turtles and birds. There was also rate variation across genes, where non-synonymous substitution rates were fastest at ATP8 and slowest at CO 3. Family-by-gene interactions were significant, indicating that local clocks vary substantially among sauropsids. Most importantly, we find evidence that mitochondrial genome evolutionary rates are positively correlated with speciation rates and with contemporary species richness. Nuclear sequences are poorly represented among reptiles, but the correlation between rates of molecular evolution and species diversification also extends to 18 avian nuclear genes we tested. Thus, the nuclear data buttress our mtDNA findings.

Wing shape and environmental energy are associated with molecular evolutionary rates in a large avian radiation

2020 ◽  
Author(s):  
David Alejandro Duchêne ◽  
Paola Montoya ◽  
Carlos Daniel Cadena
Keyword(s):  
Uv Radiation ◽  
Positive Association ◽  
Evolutionary Rates ◽  
Wing Morphology ◽  
Geographic Ranges ◽  
Molecular Evolutionary Rates ◽  
Strong Positive Association ◽  
Genomic Regions ◽  
Avian Family

AbstractAmong the macroevolutionary drivers of molecular evolutionary rates, metabolic demands and environmental energy have been a central topic of discussion. The large number of studies examining these associations have found mixed results, and have rarely explored the interactions among various factors impacting molecular evolutionary rates. Taking the diverse avian family Furnariidae as a case study, we examined the association between several estimates of molecular evolutionary rates with a proxy of metabolic demands imposed by flight (wing morphology) and proxies of environmental energy across the geographic ranges of species (temperature and UV radiation). We found a strong positive association between molecular rates in genomic regions that can change the coded amino-acid with wing morphology, environmental temperature, and UV radiation. Strikingly, however, we did not find evidence of such associations with molecular rates at sites not impacting amino-acids. Our results suggest that the demands of flight and environmental energy primarily impact genome evolution by placing selective constraints, instead of being associated with basal mutation rates.

scholarly journals Divergence time of the two regional medaka populations in Japan as a new time scale for comparative genomics of vertebrates

2009 ◽  
Vol 5 (6) ◽  
pp. 812-816 ◽  
Author(s):  
Davin H. E. Setiamarga ◽  
Masaki Miya ◽  
Yusuke Yamanoue ◽  
Yoichiro Azuma ◽  
Jun G. Inoue ◽  
...  
Keyword(s):  
Comparative Genomics ◽  
Molecular Clock ◽  
Divergence Time ◽  
Evolutionary Rates ◽  
Implicit Assumption ◽  
Molecular Evolutionary Rates ◽  
Clock Analysis ◽  
The Japanese Archipelago ◽  
Two Populations ◽  
Rates Of Molecular Evolution

The southern and northern Japanese populations of the medaka fish provide useful tools to gain insights into the comparative genomics and speciation of vertebrates, because they can breed to produce healthy and fertile offspring despite their highly divergent genetic backgrounds compared with those of human–chimpanzee. Comparative genomics analysis has suggested that such large genetic differences between the two populations are caused by higher molecular evolutionary rates among the medakas than those of the hominids. The argument, however, was based on the assumption that the two Japanese populations diverged approximately at the same time (4.0–4.7 Myr ago) as the human–chimpanzee lineage (5.0–6.0 Myr ago). This can be misleading, because the divergence time of the two populations was calculated based on estimated, extremely higher molecular evolutionary rates of other fishes with an implicit assumption of a global molecular clock. Here we show that our estimate, based on a Bayesian relaxed molecular-clock analysis of whole mitogenome sequences from 72 ray-finned fishes (including 14 medakas), is about four times older than that of the previous study (18 Myr). This remarkably older estimate can be reconciled with the vicariant events of the Japanese archipelago, and the resulting rates of molecular evolution are almost identical between the medaka and hominid lineages. Our results further highlight the fact that reproductive isolation may not evolve despite a long period of geographical isolation.

Classification of canola (Brassica napus) winter cultivars by secondary dormancy

2009 ◽  
Vol 89 (4) ◽  
pp. 613-619 ◽  
Author(s):  
S Gruber ◽  
K Emrich ◽  
W Claupein
Keyword(s):  
Cluster Analysis ◽  
Brassica Napus ◽  
Environmental Factors ◽  
Seed Bank ◽  
Soil Seed Bank ◽  
Canola Seed ◽  
Brassica Napus L ◽  
Secondary Dormancy ◽  
Specific Trait

Secondary dormancy is the major reason for seed persistence of canola (Brassica napus L.) in the soil. Volunteers emerging from the soil seed bank can lead to unwanted gene dispersal. More than 40 B. napus canola cultivars were tested for secondary dormancy under laboratory conditions. All cultivars were classified into groups of low, medium, and high dormancy by performing a cluster analysis. The results suggest that secondary dormancy is a cultivar-specific trait. Additionally, inter-year variation in dormancy indicates that it seems to be influenced by a set of environmental factors. Among years, classification of cultivars based on relative rank was more robust than classification based on absolute dormancy values. The classification of cultivars by their dormancy level would allow farmers to select and grow low-dormancy cultivars. Knowledge about the relative secondary dormancy of the currently grown cultivars could help growers and breeders lower canola seed bank persistence. Key words: Brassica napus, cluster analysis, genotype, secondary dormancy, soil seed bank

scholarly journals Soil seed bank variation patterns according to environmental factors in a natural grassland

2004 ◽  
Vol 26 (2) ◽  
pp. 126-137 ◽  
Author(s):  
Fernanda Costa Maia ◽  
Renato Borges de Medeiros ◽  
Valério de Patta Pillar ◽  
Telmo Focht
Keyword(s):  
Environmental Factors ◽  
Seed Bank ◽  
Soil Seed Bank ◽  
Chemical Properties ◽  
Low Fertility ◽  
Soil Variables ◽  
Variation Patterns ◽  
Vegetation Heterogeneity ◽  
South Of Brazil ◽  
Natural Grassland

This research aimed to determine the soil seed bank and its relationship with environmental factors that have an influence in the distribution of the vegetation above the ground in an excluded area of natural grassland in the South of Brazil. Most of the 122 identified species in the seed bank were perennials. Data analysis indicated three distinct community groups, according to the size and composition of the soil seed bank in lowlands with permanent wet soils, in lowlands and in other areas. In general, lowlands were characterized by low-fertility soils, high moisture and aluminum contents, being spatially homogeneous habitats and, therefore, more restricted to vegetation heterogeneity than other parts of the relief. Environmental factors most associated with soil seed bank size and composition were relief position and their co-related soil variables such as: soil moisture content, potassium content, organic matter, basic saturation of cation exchange soil capacity, exchangeable basics sum of the soil and clay soil content. According to that, relief position, associated with combined effects of soil chemical properties related to it, determines the observed variation pattern of the soil seed bank, as a reflection of the vegetation above the area.

scholarly journals Fenologi Rhododendron spp. (Subgenus Vireya) Koleksi Kebun Raya Eka Karya Bali

2016 ◽  
Vol 21 (3) ◽  
pp. 232
Author(s):  
Dyan Meiningsasi Putri
Keyword(s):  
Environmental Factors ◽  
Seed Bank ◽  
Botanical Garden ◽  
Seed Banks ◽  
Botanical Gardens ◽  
Temperature And Humidity ◽  
Grading Model

Hingga saat ini belum banyak data hasil penelitian tentang fenologi Rhododendron spp. Penelitian fenologi Rhododendron spp. sangat dibutuhkan untuk upaya pengembangan pemanfaatan koleksi. Studi fenologi Rhododendron spp. (Subgenus Vireya) telah dilakukan di pembibitan Kebun Raya Eka Karya Bali dari bulan Januari 2008 sampai dengan Desember 2010. Penelitian bertujuan untuk mengetahui fenologi Rhododendron spp. (Subgenus Vireya). Metode yang digunakan ialah model kelas/grading. Dari hasil pengamatan masa berbunga dan berbuah 14 jenis Rhododendron spp. yang dipelajari diketahui bahwa Rhododendron dapat dikelompokkan menjadi tiga yaitu: (1). Rhododendron yang berbunga pada bulan–bulan tertentu saja, (2)  Rhododendron yang berbunga sepanjang tahun, dan (3). Rhododendron yang belum atau tidak berbunga. Faktor lingkungan seperti suhu dan kelembaban udara juga mempengaruhi jumlah jenis Rhododendron  yang dapat berbunga dan berbuah. Bulan Mei merupakan bulan di mana paling banyak jenis Rhododendron yang berbunga, sedangkan untuk masa buah siap panen bervariasi tiap tahunnya. Hasil penelitian ini dapat dimanfaatkan untuk meningkatkan jumlah koleksi Rhododendron spp. koleksi Kebun Raya Eka Karya Bali, dasar untuk penelitian kawin silang (breeding), dan pengoleksian biji (seed bank).<br /><br /><br />Until now there are a lot of data resulted from phenology researches on of Rhododendron spp. Phenology research of Rhododendron spp. is needed to develop utility of their collection. The phenology study of Rhododendron spp. (subgenus vireya) was conducted at Bali Botanical Garden from January 2008 to Desember 2010. This study aimed to determine the phenology of Rhododendron spp. (subgenus vireya). The method used was the classroom/grading model. From the observation it was known period of flowering and fruiting 14 species of Rhododendron and grouped into three categories, namely: (1) Rhododendron which blooming in certain month only, (2) Rhododendron which blooming throughout the year, and (3) Rhododendron which not or not yet flowering. Environmental factors such as temperature and humidity also affected the amount of Rhododendron species that can flower and bear fruit. May was the appropriate month for flowering of the Rhododendron where most species flowered, while for the fruit ready for harvest varied each year. The results of this study could be used to increase the number of Rhododendron spp. collections in Bali Botanical Gardens, the basis for intercross research (breeding), and collecting of seeds (seed banks).

scholarly journals Prosopis juliflora invasion and environmental factors on density of soil seed bank in Afar Region, Northeast Ethiopia

2019 ◽  
Vol 43 (1) ◽  
Author(s):  
Wakshum Shiferaw ◽  
Tamrat Bekele ◽  
Sebsebe Demissew ◽  
Ermias Aynekulu
Keyword(s):  
Environmental Factors ◽  
Seed Bank ◽  
Native Species ◽  
Soil Seed Bank ◽  
Prosopis Juliflora ◽  
Soil Samples ◽  
Ex Situ ◽  
Litter Layer ◽  
Fecal Matter ◽  
Grazing Lands

AbstractThe aims of the study were to analyze (1) the effects of Prosopis juliflora (Prosopis) on the spatial distribution and soil seed banks (SSB) diversity and density, (2) the effects of environmental factors on SSB diversity and density (number of seeds in the soil per unit area), and (3) the effects of animal fecal droppings on SSB diversity, density, and dispersal. Aboveground vegetation data were collected from different Prosopis-infested habitats from quadrats (20 × 20 m) in Prosopis thickets, Prosopis + native species stand, non-invaded woodlands, and open grazing lands. In each Prosopis-infested habitats, soil samples were collected from the litter layer and three successive soil layer, i.e., 0–3 cm, 3–6 cm, and 6–9 cm. Seeds from soil samples and animal fecal matter were separated in the green house using the seedling emergence technique. Invasion of Prosopis had significant effects on the soil seed bank diversity. Results revealed that the mean value of the Shannon diversity of non-invaded woodlands was being higher by 19.2%, 18.5%, and 11.0% than Prosopis thickets; Prosopis + native species stand and open grazing lands, respectively. The seed diversity and richness, recovered from 6–9-cm-deep layer were the highest. On the other hand, the density of Prosopis seeds was the highest in the litter layer. About 156 of seeds/kg (92.9%) of seeds were germinated from cattle fecal matter. However, in a small proportion of seedlings, 12 of seeds/kg (7.1%) were germinated from shot fecal matter. Thus, as the seeds in the soil were low in the study areas, in situ and ex situ conservation of original plants and reseeding of persistent grass species such as Cynodon dactylon, Cenchrus ciliaris, Chrysopogon plumulosus, and Brachiaria ramosa are recommended.

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