scholarly journals Explaining the worldwide distributions of two highly mobile species: Cakile edentula and Cakile maritima

2020 ◽  
Author(s):  
Elliot C. Shaw ◽  
Rachael Fowler ◽  
Sara Ohadi ◽  
Michael J. Bayly ◽  
Rosemary A. Barrett ◽  
...  
Keyword(s):  
Mobile Species ◽  
Cakile Maritima ◽  
Cakile Edentula

scholarly journals Inheritance of breeding system in Cakile (Brassicaceae) following hybridization: implications for plant invasions

2019 ◽  
Vol 125 (4) ◽  
pp. 639-650 ◽  
Author(s):  
Chengjun Li ◽  
Mohsen B Mesgaran ◽  
Peter K Ades ◽  
Roger D Cousens
Keyword(s):  
Breeding System ◽  
Population Model ◽  
Pollen Viability ◽  
Plant Invasions ◽  
Quantitative Agreement ◽  
Fertilization Success ◽  
Breeding Systems ◽  
Success Rates ◽  
Cakile Maritima ◽  
Cakile Edentula

Abstract Background and Aims Hybridization is commonly assumed to aid invasions through adaptive introgression. In contrast, a recent theoretical model predicted that there can be non-adaptive demographic advantages from hybridization and that the population consequences will depend on the breeding systems of the species and the extent to which subsequent generations are able to interbreed and reproduce. We examined cross-fertilization success and inheritance of breeding systems of two species in order to better assess the plausibility of the theoretical predictions. Methods Reciprocal artificial crosses were made to produce F1, F2 and backcrosses between Cakile maritima (self-incompatible, SI) and Cakile edentula (self-compatible, SC) (Brassicaceae). Flowers were emasculated prior to anther dehiscence and pollen was introduced from donor plants to the recipient’s stigma. Breeding system, pollen viability, pollen germination, pollen tube growth and reproductive output were then determined. The results were used to replace the assumptions made in the original population model and new simulations were made. Key Results The success rate with the SI species as the pollen recipient was lower than when it was the pollen donor, in quantitative agreement with the ‘SI × SC rule’ of unilateral incompatibility. Similar outcomes were found in subsequent generations where fertile hybrids were produced but lower success rates were observed in crosses of SI pollen donors with SC pollen recipients. Much lower proportions of SC hybrids were produced than expected from a single Mendelian allele. When incorporated into a population model, these results predicted an even faster rate of replacement of the SC species by the SI species than previously reported. Conclusions Our study of these two species provides even clearer support for the feasibility of the non-adaptive hybridization hypothesis, whereby the colonization of an SI species can be assisted by transient hybridization with a congener. It also provides novel insight into reproductive biology beyond the F1 generation.

Invasion of the New Zealand Coastline by European Sea-Rocket (Cakile maritima) and American Sea-Rocket (Cakile edentula)

2011 ◽  
Vol 4 (2) ◽  
pp. 260-263 ◽  
Author(s):  
Roger D. Cousens ◽  
Jane M. Cousens
Keyword(s):  
New Zealand ◽  
North America ◽  
West Coast ◽  
Congeneric Species ◽  
The West ◽  
The Past ◽  
The North ◽  
Cakile Maritima ◽  
Cakile Edentula ◽  
North And South

AbstractOn the west coast of North America and in Australia, there have been parallel cases of sequential invasion and replacement of the shoreline plant American sea-rocket by European sea-rocket. A similar pattern has also occurred in New Zealand. For 30 to 40 yr, from its first recording in 1921, American sea-rocket spread throughout the eastern coastlines of the North and South Islands of New Zealand. European sea-rocket has so far been collected only on the North Island. From its first collection in 1937, European sea-rocket spread to the northern extremity of the island by 1973, and by 2010, it had reached the southernmost limit. In the region where both species have occurred in the past, American sea-rocket is now rarely found. This appears to be another example of congeneric species displacement.

scholarly journals Hybridization can facilitate species invasions, even without enhancing local adaptation

2016 ◽  
Vol 113 (36) ◽  
pp. 10210-10214 ◽  
Author(s):  
Mohsen B. Mesgaran ◽  
Mark A. Lewis ◽  
Peter K. Ades ◽  
Kathleen Donohue ◽  
Sara Ohadi ◽  
...  
Keyword(s):  
Leading Edge ◽  
Allee Effects ◽  
Plant Populations ◽  
Individual Fitness ◽  
Founding Population ◽  
Species Invasions ◽  
Cakile Maritima ◽  
Model Predictions ◽  
Cakile Edentula

The founding population in most new species introductions, or at the leading edge of an ongoing invasion, is likely to be small. Severe Allee effects—reductions in individual fitness at low population density—may then result in a failure of the species to colonize, even if the habitat could support a much larger population. Using a simulation model for plant populations that incorporates demography, mating systems, quantitative genetics, and pollinators, we show that Allee effects can potentially be overcome by transient hybridization with a resident species or an earlier colonizer. This mechanism does not require the invocation of adaptive changes usually attributed to invasions following hybridization. We verify our result in a case study of sequential invasions by two plant species where the outcrosser Cakile maritima has replaced an earlier, inbreeding, colonizer Cakile edentula (Brassicaceae). Observed historical rates of replacement are consistent with model predictions from hybrid-alleviated Allee effects in outcrossers, although other causes cannot be ruled out.

Fruit and seed polymorphism and its relation to seedling growth in the genus Cakile

1989 ◽  
Vol 67 (9) ◽  
pp. 2743-2750 ◽  
Author(s):  
M. A. Maun ◽  
A. M. Payne
Keyword(s):  
Growth Rate ◽  
Seed Mass ◽  
Germination Percentage ◽  
Dispersal Ability ◽  
Relative Growth ◽  
Frequency Distributions ◽  
Cakile Maritima ◽  
Cakile Edentula ◽  
Germination Behaviour ◽  
Better Than

To ascertain the adaptive significance of dimorphism under unpredictable environments, the dimorphic fruit segments of Cakile edentula var. lacustris, Cakile edentula var. edentula, and Cakile maritima were tested for differences in size of propagules, dispersal ability, germination behaviour, and growth rate. The upper and lower fruit segments differed in some attributes but not in others. For example, the fruits, seeds, and shells of upper segments were significantly heavier than those of lower segments. However, the frequency distributions of mean mass per seed, shell, and fruit indicated a considerable zone of overlap beneath the histograms of upper and lower fruit segments. Under still conditions in a greenhouse, no differences were found in the floating ability of upper and lower fruit segments of C. edentula var. lacustris and C. maritima. Of the three taxa, C. maritima fruits had the highest shell to seed mass ratio and floated for the longest period of time. Morphological seed dimorphism was linked with a physiological seed dimorphism. The lower fruit segments of C. edentula var. lacustris germinated better than the upper fruit segments over a wider range of temperatures. Light did not alter the final germination percentage of upper or lower fruit segments but inhibited the rate of germination. The relative growth rate decreased in all three taxa with an increase in the age of a seedling, irrespective of its seed weight.

scholarly journals Temporal and spatial variation in adult and juvenile mobile fauna associated with natural and artificial coastal habitats

2021 ◽  
Vol 168 (2) ◽  
Author(s):  
Alice E. Hall ◽  
Roger J. H. Herbert ◽  
Richard Stafford
Keyword(s):  
Dicentrarchus Labrax ◽  
Early Summer ◽  
Coastal Habitats ◽  
Artificial Structures ◽  
Artificial Habitats ◽  
Mobile Species ◽  
Spatial And Seasonal Variation ◽  
Black Bream ◽  
Temporal And Spatial ◽  
Natural Reefs

AbstractCoastal habitats are important for commercially exploited and protected species of fish and larger mobile invertebrates. The addition of artificial structures within the marine environment has the potential to alter the connectivity between habitats and to affect metapopulations of a region. Baited remote underwater videos (BRUV) were used to investigate the spatial and seasonal variation in abundance of adult and juvenile mobile species associated with subtidal natural and artificial habitats within Poole Bay on the south coast of England in 2019. Metrics included the relative maximum abundance (MaxN), number of species seen (S), assemblage structure and size range of fish. Higher values of MaxN and S were recorded on artificial structures in the spring and early summer; however, this pattern was reversed by mid-summer and early autumn when more fish were recorded on the natural reefs. Yet overall differences in MaxN and S between habitats were not significant. Differences in assemblage composition between habitats varied monthly, but this was mostly driven by particular sites. Although most fish observed were juveniles, there were some seasonal differences in the size of fish using natural and artificial sites, especially bib (Trisopterus luscus), black bream (Spondyliosoma cantharus), bass (Dicentrarchus labrax) and pollack (Pollachius pollachius). The artificial habitats in this region appeared to be important in certain months, so temporal studies of this type need to be incorporated within surveys, particularly those in proximity to protected areas.

scholarly journals Theory of the Thermal Stability of Silicon Vacancies and Interstitials in 4H–SiC

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 167
Author(s):  
José Coutinho
Keyword(s):  
Thermal Stability ◽  
Fermi Level ◽  
Density Functional ◽  
Dynamic Properties ◽  
Type Material ◽  
Temperature Threshold ◽  
Effect Analysis ◽  
Mobile Species ◽  
Two Stages ◽  
Thermal Stability Of

This paper presents a theoretical study of the electronic and dynamic properties of silicon vacancies and self-interstitials in 4H–SiC using hybrid density functional methods. Several pending issues, mostly related to the thermal stability of this defect, are addressed. The silicon site vacancy and the carbon-related antisite-vacancy (CAV) pair are interpreted as a unique and bistable defect. It possesses a metastable negative-U neutral state, which “disproportionates” into VSi+ or VSi−, depending on the location of the Fermi level. The vacancy introduces a (−/+) transition, calculated at Ec−1.25 eV, which determines a temperature threshold for the annealing of VSi into CAV in n-type material due to a Fermi level crossing effect. Analysis of a configuration coordinate diagram allows us to conclude that VSi anneals out in two stages—at low temperatures (T≲600 °C) via capture of a mobile species (e.g., self-interstitials) and at higher temperatures (T≳1200 °C) via dissociation into VC and CSi defects. The Si interstitial (Sii) is also a negative-U defect, with metastable q=+1 and q=+3 states. These are the only paramagnetic states of the defect, and maybe that explains why it escaped detection, even in p-type material where the migration barriers are at least 2.7 eV high.

scholarly journals Molecular Dynamics Simulations of Crystal Nucleation near Interfaces in Incompatible Polymer Blends

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 347
Author(s):  
Wenlin Zhang ◽  
Lingyi Zou
Keyword(s):  
Molecular Dynamics ◽  
Polymer Blends ◽  
Md Simulations ◽  
Nucleation And Growth ◽  
Crystal Nucleation ◽  
Crystalline Order ◽  
Mobile Species ◽  
Deep Supercooling ◽  
Crystallizable Polymer ◽  
Dynamics Simulations

We apply molecular dynamics (MD) simulations to investigate crystal nucleation in incompatible polymer blends under deep supercooling conditions. Simulations of isothermal nucleation are performed for phase-separated blends with different degrees of incompatibility. In weakly segregated blends, slow and incompatible chains in crystallizable polymer domains can significantly hinder the crystal nucleation and growth. When a crystallizable polymer is blended with a more mobile species in interfacial regions, enhanced molecular mobility leads to the fast growth of crystalline order. However, the incubation time remains the same as that in pure samples. By inducing anisotropic alignment near the interfaces of strongly segregated blends, phase separation also promotes crystalline order to grow near interfaces between different polymer domains.

scholarly journals Patterns of intraspecific morphological variability in soil mites reflect their dispersal ability

2021 ◽  
Vol 83 (2) ◽  
pp. 241-255
Author(s):  
Julia Baumann
Keyword(s):  
Molecular Genetic ◽  
Morphological Variability ◽  
Mite Species ◽  
Molecular Genetic Analysis ◽  
Dispersal Ability ◽  
Geometric Morphometric ◽  
Geographic Population ◽  
Mobile Species ◽  
Population Structures ◽  
Subdivided Populations

AbstractThe ability to disperse is one of the most important factors influencing the biogeography of species and speciation processes. Highly mobile species have been shown to lack geographic population structures, whereas less mobile species show genetically strongly subdivided populations which are expected to also display at least subtle phenotypic differences. Geometric morphometric methods (GMM) were now used to analyze morphological differences between European populations of a presumed non-phoretic, little mobile mite species in comparison to a highly mobile, phoretic species. The non-phoretic species Scutacarus carinthiacus showed a phenotypic population structure, whereas the phoretic species S. acarorum displayed homogeneity. These different patterns most probably can be explained by different levels of gene flow due to different dispersal abilities of the two species. GMM proved to be a sensitive tool that is especially recommendable for the analysis of (old) museum material and/or specimens in microscopic slides, which are not suitable for molecular genetic analysis.

scholarly journals Moving apart together: co-movement of a symbiont community and their ant host, and its importance for community assembly

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
T. Parmentier ◽  
R. Claus ◽  
F. De Laender ◽  
D. Bonte
Keyword(s):  
Community Assembly ◽  
Species Interactions ◽  
Spatial Dynamics ◽  
Joint Movement ◽  
Red Wood Ants ◽  
Ant Nests ◽  
Mobile Species ◽  
Directional Movement ◽  
Wood Ants ◽  
Red Wood Ant

Abstract Background Species interactions may affect spatial dynamics when the movement of one species is determined by the presence of another one. The most direct species-dependence of dispersal is vectored, usually cross-kingdom, movement of immobile parasites, diseases or seeds by mobile animals. Joint movements of species should, however, not be vectored by definition, as even mobile species are predicted to move together when they are tightly connected in symbiont communities. Methods We studied concerted movements in a diverse and heterogeneous community of arthropods (myrmecophiles) associated with red wood ants. We questioned whether joint-movement strategies eventually determine and speed-up community succession. Results We recorded an astonishingly high number of obligate myrmecophiles outside red wood ant nests. They preferentially co-moved with the host ants as the highest densities were found in locations with the highest density of foraging red wood ants, such as along the network of ant trails. These observations suggest that myrmecophiles resort to the host to move away from the nest, and this to a much higher extent than hitherto anticipated. Interestingly, functional groups of symbionts displayed different dispersal kernels, with predatory myrmecophiles moving more frequently and further from the nest than detritivorous myrmecophiles. We discovered that myrmecophile diversity was lower in newly founded nests than in mature red wood ant nests. Most myrmecophiles, however, were able to colonize new nests fast suggesting that the heterogeneity in mobility does not affect community assembly. Conclusions We show that co-movement is not restricted to tight parasitic, or cross-kingdom interactions. Movement in social insect symbiont communities may be heterogeneous and functional group-dependent, but clearly affected by host movement. Ultimately, this co-movement leads to directional movement and allows a fast colonisation of new patches, but not in a predictable way. This study highlights the importance of spatial dynamics of local and regional networks in symbiont metacommunities, of which those of symbionts of social insects are prime examples.

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