scholarly journals Evolution in novel environments: do restored prairie populations experience strong selection?

2019 ◽  
Author(s):  
Susan M. Magnoli ◽  
Jennifer A. Lau
Keyword(s):  
Source Population ◽  
Plant Populations ◽  
Strong Selection ◽  
Common Gardens ◽  
Close Proximity ◽  
Established Plant ◽  
Restored Prairie ◽  
Prairie Restorations ◽  
Time Specific ◽  
New Habitats

AbstractWhen populations colonize new habitats, they are likely to experience novel environmental conditions, and as a consequence may experience strong selection. While selection and the resulting evolutionary responses may have important implications for establishment success in colonizing populations, few studies have estimated selection in such scenarios. Here we examined evidence of selection in recently established plant populations in two prairie restorations in close proximity (< 15 km apart) using two approaches: 1) we tested for evidence of past selection on a suite of traits in two Chamaecrista fasciculata populations by comparing the restored populations to each other and their shared source population in common gardens to quantify evolutionary responses and 2) we measured selection in the field. We found evidence of past selection on flowering time, specific leaf area, and root nodule production in one of the populations, but detected contemporary selection on only one trait (plant height). This demonstrates that while selection can occur in colonizing populations, resulting in significant evolutionary responses in less than 6 generations, rapid evolutionary responses may be weak in even nearby populations sown with the same source population. Because contemporary measures of selection rarely predicted observed evolutionary responses, it also suggests that selection likely differs over the early stages of succession that characterize young prairies.

scholarly journals Plasticity of plant defense and its evolutionary implications in wild populations of Boechera stricta

2017 ◽  
Author(s):  
Maggie R. Wagner ◽  
Thomas Mitchell-Olds
Keyword(s):  
Natural Selection ◽  
Environmental Gradient ◽  
Natural Populations ◽  
Reaction Norm ◽  
Relative Fitness ◽  
Adaptive Plasticity ◽  
Common Gardens ◽  
Evolutionary Trajectories ◽  
Boechera Stricta ◽  
New Habitats

AbstractPhenotypic plasticity is thought to impact evolutionary trajectories by shifting trait values in a direction that is either favored by natural selection (“adaptive plasticity”) or disfavored (“nonadaptive” plasticity). However, it is unclear how commonly each of these types of plasticity occurs in natural populations. To answer this question, we measured glucosinolate defensive chemistry and reproductive fitness in over 1,500 individuals of the wild perennial mustard Boechera stricta, planted in four common gardens across central Idaho, USA. Glucosinolate profiles—including total glucosinolate quantity as well as the relative abundances and overall diversity of different compounds—were strongly plastic both among habitats and within habitats. Patterns of glucosinolate plasticity varied greatly among genotypes. More often than expected by chance, glucosinolate profiles shifted in a direction that matched the direction of natural selection, indicating that plasticity among habitats tended to increase relative fitness. In contrast, we found no evidence for within-habitat selection on glucosinolate reaction norm slopes (i.e., plasticity along a continuous environmental gradient). Together, our results indicate that glucosinolate plasticity may improve the ability of B. stricta populations to persist after migration to new habitats.

Response of nine genotypes of irrigated soybeans to planting pattern and sowing date

1980 ◽  
Vol 20 (102) ◽  
pp. 88 ◽  
Author(s):  
GA Constable ◽  
IA Rose
Keyword(s):  
Sowing Date ◽  
The Other ◽  
Average Increase ◽  
Plant Populations ◽  
Planting Pattern ◽  
Breeding Lines ◽  
Yield Increase ◽  
Sowing Dates ◽  
Established Plant ◽  
New Cultivars

A three year study compared the response of promising breeding lines, new cultivars and commercial soybean cultivars to three planting patterns and two sowing dates. The planting patterns were: 25-45 cm rows on 200 cm wide beds, twin 15 cm rows on 100 cm hills, and single rows on 100 cm hills. In all planting patterns, the established plant populations were 20-25 m-2. The sowing dates were December 1 or 5 and January 15 or 22. There was a yield increase of up to 14% (433 kg ha-1) with narrow rows on wide beds and twin rows over 100 cm rows, the extent depending on cultivar and season, with an overall average increase of only 5 to 8%. In the two seasons where narrow rows yielded more than 100 cm rows, cv. Forrest yielded best in twin rows, while the other genotypes yielded best with narrow rows on wide beds. These effects were the same for both sowing dates. January sowings yielded 30% less than December sowings, but this decline in yield was least evident in cvv. Forrest and Ruse. Forrest was the highest yielding cultivar for both sowing dates in every season (3605 and 271 6 kg ha-1 respectively). We conclude that the small increase in yield with narrow rows may be worthwhile economically, as long as no extra costs are involved. The planting pattern and sowing date response of promising lines should be examined as part of a breeding program.

Ficus subgen. Ficus . Two rare and primitive pachycaul species

1970 ◽  
Vol 259 (831) ◽  
pp. 353-381 ◽  
Keyword(s):  
New Species ◽  
Growth Forms ◽  
Limited Distribution ◽  
Close Proximity ◽  
The Common ◽  
Floral Characters ◽  
New Britain ◽  
A New Species ◽  
New Habitats

Ficus diamantiphylla (sect. Ficus ser. Auratae Corner) is described as a new species from Borneo, F. sciaphila (sect. Sycidium Miq. ser. Copiosae Corner) as a new species from New Britain. Both are small pachycaul trees of limited distribution presenting the most primitive vegetative and floral characters in their series. They contrast with the leptocaul species which, with advanced structure, become the common and widespread members of the series. Both species illustrate the manner in which subgeneric evolution, origin and dispersal can be learnt from the pachycaul-leptocaul sequence. F. diamantiphylla places the origin of ser. Auratae in Borneo where the series is mainly endemic. It links with the widespread ser. Eriosyceae Corner, and it is shown how subsect. Eriosycea (Miq.) Corner bears upon the Sino-Himalayan origin of ser. Cariceae Corner with F. carica L. Specific evolution involves the production of new growth-forms and the occupation of new habitats; vicariism plays so little, if any, part that primitive and advanced species live in the same forest. F. sciaphila places the origin of ser. Copiosae , so far as the species with smooth seeds is concerned, in Melanesia in close proximity with ser. Phaeopilosae Corner and ser. Scabrae Miq. It is the pachycaul antecedent to the common and widespread F. copiosa Steud. and F. wassa Roxb.

scholarly journals The effect of increasing plant population on maize silage yield and quality

2003 ◽  
pp. 117-121
Author(s):  
R.J. Densley ◽  
R.J. Brenton-Rule ◽  
G.M. Austin ◽  
D.W. Densley ◽  
R. Tsimba
Keyword(s):  
Dry Matter ◽  
Plant Population ◽  
Maize Silage ◽  
Higher Plant ◽  
Plant Populations ◽  
The Past ◽  
Yield And Quality ◽  
Established Plant ◽  
Modern Maize

For the past decade maize silage has been planted at 100000 plants/ha in New Zealand. Modern maize silage hybrids have enhanced stress tolerance making them more adaptable to higher plant populations. This study examined the effect of a range of established plant populations (85000, 100000, 115000, 130000 and 145000 plants/ha) on the yield and quality of 12 Pioneer® brand maize silage hybrids grown at 13 locations over two seasons. As plant population increased maize silage dry matter (DM) yield increased significantly (P

Field frequency and pattern of inheritance of the herbivory-defence trait “resistance-by-ducking” in the giant goldenrod (Solidago gigantea, Asteraceae)

2018 ◽  
Vol 151 (2) ◽  
pp. 271-277 ◽  
Author(s):  
Michael J. Wise
Keyword(s):  
Evolutionary Dynamics ◽  
Major Gene ◽  
Large Field ◽  
Source Population ◽  
Plant Populations ◽  
Field Frequency ◽  
Solidago Gigantea ◽  
Herbivore Interactions ◽  
Genetic Mechanisms ◽  
Plant Herbivore

Background and aims – For a more complete understanding of the eco-evolutionary dynamics of plant-herbivore interactions, it is important to know the genetic mechanisms that control defence traits, as well as the levels of genetic variation for these traits in plant populations. Here, I present results of a study of the occurrence and pattern of inheritance of the recently discovered trait of ‘resistance-by-ducking’ in the goldenrod Solidago gigantea (Asteraceae).Methods – I grew maternal families of seedlings from fruits collected in a large field population of S. gigantea in southwestern Virginia, USA. I determined stem phenotype (ducking or erect) for 704 plants across 36 maternal families.Key results – Of the 704 plants, 72% had ducking stems and 28% had erect stems. Employing bootstrapping with Hardy-Weinberg principles, I found that the pattern of inheritance was consistent with stem phenotype being controlled by a major gene, with the ducking morph being recessive to the erect morph. The allele frequencies for stem phenotype in the source population were estimated to be 0.85 ducking and 0.15 erect alleles.Conclusions – These findings not only help inform ecological studies of ducking in S. gigantea, but they lay the groundwork for comparative studies of similar goldenrod species whose populations have differing proportions of ducking stems. For example, in all previous studies on populations of S. altissima, ducking stems have been the minority morph, occurring at a frequency of less than 20%. These results suggest that ducking may be costlier in S. altissima, while S. gigantea may face different ecological pressures, or has somehow overcome some of the costs of ducking.

scholarly journals Source population characteristics affect heterosis following genetic rescue of fragmented plant populations

2013 ◽  
Vol 280 (1750) ◽  
pp. 20122058 ◽  
Author(s):  
M. Pickup ◽  
D. L. Field ◽  
D. M. Rowell ◽  
A. G. Young
Keyword(s):  
Evolutionary Biology ◽  
Population Characteristics ◽  
Outbreeding Depression ◽  
Source Population ◽  
Genetic Rescue ◽  
Fitness Components ◽  
Plant Populations ◽  
High Genetic Diversity ◽  
Perennial Plant ◽  
Experimental Crosses

Understanding the relative importance of heterosis and outbreeding depression over multiple generations is a key question in evolutionary biology and is essential for identifying appropriate genetic sources for population and ecosystem restoration. Here we use 2455 experimental crosses between 12 population pairs of the rare perennial plant Rutidosis leptorrhynchoides (Asteraceae) to investigate the multi-generational (F 1 , F 2 , F 3 ) fitness outcomes of inter-population hybridization. We detected no evidence of outbreeding depression, with inter-population hybrids and backcrosses showing either similar fitness or significant heterosis for fitness components across the three generations. Variation in heterosis among population pairs was best explained by characteristics of the foreign source or home population, and was greatest when the source population was large, with high genetic diversity and low inbreeding, and the home population was small and inbred. Our results indicate that the primary consideration for maximizing progeny fitness following population augmentation or restoration is the use of seed from large, genetically diverse populations.

Effects of Vincristine on Endothelial Microtubules in the Spinal Cord

1976 ◽  
Vol 34 ◽  
pp. 58-59
Author(s):  
John L. Beggs ◽  
John D. Waggener ◽  
Wanda Miller
Keyword(s):  
Spinal Cord ◽  
Biological Activity ◽  
Horseradish Peroxidase ◽  
Transport Mechanism ◽  
Vasogenic Edema ◽  
Vesicular Transport ◽  
Close Proximity

Microtubules (MT) are versatile organelles participating in a wide variety of biological activity. MT involvement in the movement and transport of cytoplasmic components has been well documented. In the course of our study on trauma-induced vasogenic edema in the spinal cord we have concluded that endothelial vesicles contribute to the edema process. Using horseradish peroxidase as a vascular tracer, labeled endothelial vesicles were present in all situations expected if a vesicular transport mechanism was in operation. Frequently,labeled vesicles coalesced to form channels that appeared to traverse the endothelium. The presence of MT in close proximity to labeled vesicles sugg ested that MT may play a role in vesicular activity.

Experiments with a scanning tunneling microscope (STM) mounted in a scanning electron microscope (SEM)

1986 ◽  
Vol 44 ◽  
pp. 636-639
Author(s):  
Oliver C. Wells ◽  
Mark E. Welland
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Mechanical Stability ◽  
Tunneling Current ◽  
Feedback System ◽  
Scanning Tunneling ◽  
Surface Profiling ◽  
Close Proximity ◽  
Metal Tip ◽  
Scanning Electron

Scanning tunneling microscopes (STM) exist in two versions. In both of these, a pointed metal tip is scanned in close proximity to the specimen surface by means of three piezos. The distance of the tip from the sample is controlled by a feedback system to give a constant tunneling current between the tip and the sample. In the low-end STM, the system has a mechanical stability and a noise level to give a vertical resolution of between 0.1 nm and 1.0 nm. The atomic resolution STM can show individual atoms on the surface of the specimen.A low-end STM has been put into the specimen chamber of a scanning electron microscope (SEM). The first objective was to investigate technological problems such as surface profiling. The second objective was for exploratory studies. This second objective has already been achieved by showing that the STM can be used to study trapping sites in SiO2.

Ultrastructure and Senescence in an Achloroplastic Mutant of Hordeum vulgare L. cv. Dyan

1992 ◽  
Vol 50 (1) ◽  
pp. 844-845
Author(s):  
R.H.M. Cross ◽  
C.E.J. Botha ◽  
A.K. Cowan ◽  
B.J. Hartley
Keyword(s):  
Cell Wall ◽  
Hordeum Vulgare ◽  
Leaf Tissue ◽  
Ultrastructural Changes ◽  
Hordeum Vulgare L ◽  
Mesophyll Cells ◽  
Lethal Mutant ◽  
Cytoplasmic Matrix ◽  
Close Proximity ◽  
Pinocytotic Vesicles

Senescence is an ordered degenerative process leading to death of individual cells, organs and organisms. The detection of a conditional lethal mutant (achloroplastic) of Hordeum vulgare has enabled us to investigate ultrastructural changes occurring in leaf tissue during foliar senescence.Examination of the tonoplast structure in six and 14 day-old mutant tissue revealed a progressive degeneration and disappearance of the membrane, apparently starting by day six in the vicinity of the mitochondria associated with the degenerating proplastid (Fig. 1.) where neither of the plastid membrane leaflets is evident (arrows, Fig. 1.). At this stage there was evidence that the mitochondrial membranes were undergoing retrogressive changes, coupled with disorganization of cristae (Fig. 2.). Proplastids (P) lack definitive prolamellar bodies. The cytoplasmic matrix is largely agranular, with few endoplasmic reticulum (ER) cisternae or polyribosomal aggregates. Interestingly, large numbers of actively-budding dictysomes, associated with pinocytotic vesicles, were observed in close proximity to the plasmalemma of mesophyll cells (Fig. 3.). By day 14 however, mesophyll cells showed almost complete breakdown of subcellular organelle structure (Fig. 4.), and further evidence for the breakdown of the tonoplast. The final stage of senescence is characterized by the solubilization of the cell wall due to expression and activity of polygalacturonase and/or cellulose. The presence of dictyosomes with associated pinocytotic vesicles formed from the mature face, in close proximity to both the plasmalemma and the cell wall, would appear to support the model proposed by Christopherson for the secretion of cellulase. This pathway of synthesis is typical for secretory glycoproteins.

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