scholarly journals Proximate causes and possible adaptive functions of mast seeding and barren flower shows in spinifex grasses (Triodia spp.) in arid regions of Australia

2014 ◽  
Vol 36 (3) ◽  
pp. 297 ◽  
Author(s):  
Boyd R. Wright ◽  
Alain F. Zuur ◽  
Gary C. K. Chan
Keyword(s):  
Arid Regions ◽  
Seed Set ◽  
Heavy Rain ◽  
Mast Seeding ◽  
High Yield ◽  
Seed Predator ◽  
Related Form ◽  
Proximate Causes ◽  
High Precipitation ◽  
Seed Crops

Mast seeding, the intermittent production of large synchronised seed crops among plant populations, is a phenomenon that occurs at exceptionally long intervals in spinifex grasses (Triodia spp.) from arid regions of Australia. This is despite the reliance of these fire-sensitive plants on seeds for post-fire regeneration, and that spinifex grasslands rate among Australia’s most flammable ecosystems. The proximate causes and possible adaptive functions of masting in seven species of spinifex from arid regions within the 350-mm rainfall isohyet were investigated. Specifically, the seed set percentages of 79 specimens collected between 1947 and 2012 were related to the following environmental covariates: antecedent rainfall over 6, 12 and 36 months, relative humidity, and the number of days above 40°C and below 0°C during anthesis. Given the potential importance of seeding events for post-fire regeneration, it was also investigated whether masting in Triodia could represent a fire-related form of environmentally predictive masting, by testing whether high-yield years corresponded to years of increased fire occurrence. Examination of the dataset showed that 43% of specimens contained completely aborted inflorescences (0% seed fill), while seed set ranged from 2 to 69% in the remaining specimens. High levels of insect activity were also found, with 42% of specimens showing evidence of insect occupation. Statistical analyses showed that the main environmental driver of seed set was high precipitation over the previous 12 months, and that high-yield years were strongly related to years of increased fire likelihood. The number of days over 40°C was a weakly significant driver of yield, while the remaining covariates were not significant. It is hypothesised that intermittent reproduction by Triodia is a fire-related form of environmentally predictive masting, which maximises chances of post-fire regeneration by satiating seed predators during flammable periods (i.e. after heavy rain years). Furthermore, it is suggested that non-viable flower crops after initial low rainfalls may have an adaptive function, by diluting pre-dispersal seed predator densities with ‘decoy’ ovules that do not mature and lead to the starvation of developing larvae.

scholarly journals Inter-annual variation in seed production has increased over time (1900–2014)

2017 ◽  
Vol 284 (1868) ◽  
pp. 20171666 ◽  
Author(s):  
Ian S. Pearse ◽  
Jalene M. LaMontagne ◽  
Walter D. Koenig
Keyword(s):  
Seed Production ◽  
Seed Set ◽  
Global Climate ◽  
Mast Seeding ◽  
Plant Seed ◽  
Subtle Change ◽  
Animal Populations ◽  
Wide Range ◽  
Seed Crops ◽  
Over Time

Mast seeding, or masting, is the highly variable and spatially synchronous production of seeds by a population of plants. The production of variable seed crops is typically correlated with weather, so it is of considerable interest whether global climate change has altered the variability of masting or the size of masting events. We compiled 1086 datasets of plant seed production spanning 1900–2014 and from around the world, and then analysed whether the coefficient of variation (CV) in seed set, a measure of masting, increased over time. Over this 115-year period, seed set became more variable for plants as a whole and for the particularly well-studied taxa of conifers and oaks. The increase in CV corresponded with a decrease in the long-term mean of seed set of plant species. Seed set CV increased to a greater degree in plant taxa with a tendency towards masting. Seed set is becoming more variable among years, especially for plant taxa whose masting events are known to affect animal populations. Such subtle change in reproduction can have wide-ranging effects on ecosystems because seed crops provide critical resources for a wide range of taxa and have cascading effects throughout food webs.

scholarly journals Cone characteristics and insect predation levels vary across years in mast seeding white spruce

2021 ◽  
Author(s):  
Abigail C Leeper ◽  
Jalene M LaMontagne
Keyword(s):  
Seed Predation ◽  
Mixed Models ◽  
Linear Mixed Models ◽  
Population Level ◽  
White Spruce ◽  
Mast Seeding ◽  
Seed Predator ◽  
Cone Production ◽  
Insect Predation ◽  
Seed Crops

Populations of many tree species exhibit synchronous and highly temporally variable seed crops across years. This is called mast seeding, and there are two predominant hypotheses for this pattern of reproduction, pollination efficiency and seed-predator satiation. Mast seeding studies typically involve records of population-level reproduction, with less information on the characteristics of reproductive structures. Here, we use data across six years (2012-2017), spanning a range of population-level cone conditions, to characterize i) white spruce (Picea glauca) cone lengths and seeds per cone, and ii) levels of seed predation. We quantified population-level cone production and collected 1,399 cones from a total of 38 trees in the Huron Mountains, Michigan, USA. Linear mixed models showed that mean and minimum cone lengths varied significantly across years; both being longest during the greatest cone production year. Larger cones had more seeds and the slopes of the relationships as well as the intercepts varied significantly across years. Generalized linear mixed models and AIC model selection showed that cones with insect predation damage was greatest when population-level reproduction was the lowest, with a mean proportion of cones damaged 0.82 in that year. Our findings show that white spruce cone characteristics and losses to insect seed predation vary temporally, and follow expectations based on mast seeding hypotheses.

scholarly journals The functional response of a hoarding seed predator to mast seeding

Ecology ◽  
2010 ◽  
Vol 91 (9) ◽  
pp. 2673-2683 ◽  
Author(s):  
Quinn E. Fletcher ◽  
Stan Boutin ◽  
Jeffrey E. Lane ◽  
Jalene M. LaMontagne ◽  
Andrew G. McAdam ◽  
...  
Keyword(s):  
Functional Response ◽  
Mast Seeding ◽  
Seed Predator

scholarly journals Developing new lines of Japonica rice for higher quality and yield under arid conditions

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11592
Author(s):  
Mahmoud A.A. El Sayed ◽  
Ahmed M.S. Kheir ◽  
Fatma A. Hussein ◽  
Esmat F. Ali ◽  
Mahmoud E. Selim ◽  
...  
Keyword(s):  
Arid Regions ◽  
Mineral Elements ◽  
Quality Characteristics ◽  
High Yield ◽  
Japonica Rice ◽  
Total Production ◽  
Growing Seasons ◽  
Yield And Quality ◽  
Arid Conditions ◽  
Food Security And Nutrition

Rice is the world’s largest food crop, and its production needs to be doubled by 2050 to cope with population growth and associated demand. In addition to the value of improving yields, quality is also important for breeders and consumers, but it pays less attention in arid regions. During two successive summer growing seasons, the experimental material focused on 34 genotypes developed from different crosses on Fn generation after fixation as well as six of the most recent commercial cultivars used for comparisons. The results showed that a high yield of grain followed by high milling and grain quality characteristics were observed among the 34 genotypes used in this analysis. Highly important and positive correlations between the percentage of hulling and the percentage of milling (0.424) and the yield ability could be accomplished by choosing the number of panicles per plant and the weight of the panicles. Selection criteria for good quality should be met by the percentage of head rice and many mineral elements, particularly zinc and iron. As a consequence, the genotypes M.J 5460S/SK105-1, M.J 5460S/GZ7768-1, M.J 5460S/G177-1, M.J 5460S/SK105-3 and M.J 5460S/SK106-4 had desirable high yield and quality characteristics and could be used as promising accessions to the rice breeding program in arid regions. In addition to commercial genotypes, improved Japonica rice genotypes could be produced in arid conditions for higher yield and quality, leading to an increase in total production, supporting food security and nutrition.

scholarly journals Seed masting causes fluctuations in optimum litter size and lag load in a seed predator

2018 ◽  
Author(s):  
Andrew McAdam ◽  
Stan Boutin ◽  
Ben Dantzer ◽  
Jeff Lane
Keyword(s):  
Litter Size ◽  
Picea Glauca ◽  
Life Histories ◽  
Local Density ◽  
White Spruce ◽  
Tamiasciurus Hudsonicus ◽  
Seed Predator ◽  
Red Squirrels ◽  
Seed Predators ◽  
Seed Crops

The episodic production of large seed crops by some perennial plants, is referred to as masting and is known to increase seed escape by alternately starving and swamping seed predators. These pulses of resources, however, might also act as an agent of selection on the life histories of seed predators, which could indirectly enhance seed escape by inducing an evolutionary load on seed predator populations. Lag loads in seed predators could result from mast-induced shifts in optimum phenotypes that exceed the capacity of seed predators to adaptively track optimum phenotypes through phenotypic plasticity. Alternatively, masting could generate mismatches in selection across generations, where adaptation to the parental environment leads to maladaptation in the offspring environment. Here we measured natural selection on female North American red squirrels (Tamiasciurus hudsonicus) across 28 years and five white spruce (Picea glauca) masting events. Red squirrel litter sizes were similar to optimum litter sizes during non-mast years, but were well below optimum litter sizes during resource-rich mast years. Mast events, therefore caused selection for larger litters (B = 0.25) and a lag load (L = 0.25) on red squirrels during mast years. Furthermore, we found that the annual fitness of spruce trees was negatively related to the local density of squirrels during mast years, indicating that the observed lag load on squirrels enhanced the number of spruce cones escaping squirrel predation. Although, the frequency of mast events and the demography of red squirrels were such that offspring and parents often experienced opposite environments with respect to the mast, we found no effect of environmental mismatches across generations on either offspring survival or population growth. Instead, squirrels plastically increased litter sizes in anticipation of mast events, which partially, although not completely, reduced the lag load resulting from this change in food availability. Variable selection on litter size caused by white spruce mast events, therefore, induced a lag load on the population of red squirrels that was not affected by whether individual squirrels were born during mast (matching) or non-mast (mismatching) conditions.

scholarly journals Studying the genetic basis of masting

2021 ◽  
Vol 376 (1839) ◽  
Author(s):  
Akiko Satake ◽  
Dave Kelly
Keyword(s):  
Genetic Basis ◽  
Molecular Mechanisms ◽  
Mast Seeding ◽  
Ecological Genomics ◽  
Theme Issue ◽  
Natural Conditions ◽  
Genetic Level ◽  
Seed Crops

The mechanisms underlying mast seeding have traditionally been studied by collecting long-term observational data on seed crops and correlating seedfall with environmental variables. Significant progress in ecological genomics will improve our understanding of the evolution of masting by clarifying the genetic basis of masting traits and the role of natural selection in shaping those traits. Here, we summarize three important aspects in studying the evolution of masting at the genetic level: which traits govern masting, whether those traits are genetically regulated, and which taxa show wide variation in these traits. We then introduce recent studies on the molecular mechanisms of masting. Those studies measure seasonal changes in gene expression in natural conditions to quantify how multiple environmental factors combine to regulate floral initiation, which in many masting plant species is the single largest contributor to among-year variation in seed crops. We show that Fagaceae offers exceptional opportunities for evolutionary investigations because of its diversity at both the phenotypic and genetic levels and existing documented genome sequences. This article is part of the theme issue ‘The ecology and evolution of synchronized seed production in plants’.

Testing the environmental prediction hypothesis for mast-seeding in California oaks

2010 ◽  
Vol 40 (11) ◽  
pp. 2115-2122 ◽  
Author(s):  
Walter D. Koenig ◽  
Johannes M.H. Knops ◽  
William J. Carmen
Keyword(s):  
Mast Seeding ◽  
Acorn Production ◽  
Large Seed ◽  
Significant Relationships ◽  
The Mean ◽  
Seedling Germination ◽  
Environmental Prediction ◽  
Seed Crops ◽  
Independent Site

We analyzed 29 years of acorn production by five species of California oaks (genus Quercus ) to test the hypothesis that trees produce large seed crops prior to wet years, conditions facilitating seedling germination and survival. The mean crop of three of the species correlated positively and nontrivially with the following year’s rainfall, but none was statistically significant. Including the acorn crop 1 and 2 years earlier yielded several significant relationships between the acorn crop and future rainfall, but none held up when applied to a second, independent site. Across individuals, acorn production by 7% of trees correlated significantly with subsequent rainfall. Although these trees differed from other trees in several characters, differences were not sufficient to discriminate between trees that correlated significantly with subsequent rainfall from those that did not. We conclude that acorn production by California oaks does not forecast wet years and does not support the environmental prediction hypothesis.

scholarly journals The ecology and evolution of synchronized reproduction in long-lived plants

2021 ◽  
Vol 376 (1839) ◽  
Author(s):  
Mario B. Pesendorfer ◽  
Davide Ascoli ◽  
Michał Bogdziewicz ◽  
Andrew Hacket-Pain ◽  
Ian S. Pearse ◽  
...  
Keyword(s):  
Seed Production ◽  
Predictive Modelling ◽  
Ecosystem Dynamics ◽  
Mast Seeding ◽  
Plant Reproductive Success ◽  
Proximate Mechanisms ◽  
Human Interactions ◽  
Molecular Approaches ◽  
Ontogenetic Trajectory ◽  
Seed Crops

Populations of many long-lived plants exhibit spatially synchronized seed production that varies extensively over time, so that seed production in some years is much higher than on average, while in others, it is much lower or absent. This phenomenon termed masting or mast seeding has important consequences for plant reproductive success, ecosystem dynamics and plant–human interactions. Inspired by recent advances in the field, this special issue presents a series of articles that advance the current understanding of the ecology and evolution of masting. To provide a broad overview, we reflect on the state-of-the-art of masting research in terms of underlying proximate mechanisms, ontogeny, adaptations, phylogeny and applications to conservation. While the mechanistic drivers and fitness consequences of masting have received most attention, the evolutionary history, ontogenetic trajectory and applications to plant–human interactions are poorly understood. With increased availability of long-term datasets across broader geographical and taxonomic scales, as well as advances in molecular approaches, we expect that many mysteries of masting will be solved soon. The increased understanding of this global phenomenon will provide the foundation for predictive modelling of seed crops, which will improve our ability to manage forests and agricultural fruit and nut crops in the Anthropocene. This article is part of the theme issue ‘The ecology and evolution of synchronized seed production in plants’.

scholarly journals Small arthropods as pollinators in a New Zealand pak choi field trial

2009 ◽  
Vol 62 ◽  
pp. 92-98 ◽  
Author(s):  
M.K. Walker ◽  
B.G. Howlett ◽  
J.A. McCallum ◽  
A.R. Wallace ◽  
D.A.J. Teulon
Keyword(s):  
Gene Flow ◽  
New Zealand ◽  
Body Length ◽  
Honey Bees ◽  
Seed Set ◽  
Long Distance ◽  
Pak Choi ◽  
Brassica Crops ◽  
Seed Crops

Brassica seed crops are grown throughout New Zealand and worldwide and intercrop and cropweed contamination through gene flow is a major concern For Brassica large arthropods (body length > 3 mm) particularly honey bees are the most important pollinators and are considered key vectors of pollen Small arthropods (body length < 3 mm) are also abundant in Brassica crops but their role as pollinators is rarely assessed Numerous small arthropods (particularly Diptera and Thysanoptera) were recorded within cages surrounding pak choi inflorescences that excluded large arthropods Inflorescences inside these cages set seed but seed set was significantly reduced compared with inflorescences in cages that were hand pollinated and uncaged inflorescences Although the presence of large arthropods significantly increased seed set the role of small arthropods and wind cannot be excluded in pak choi pollination Further studies are required to fully determine the role of small arthropods in long distance pollen flow

Experimental studies on seed production of tropical grasses in Kenya. 5. The effect of time of nitrogen top dressing on seed crops of Setaria sphacelata cv. Nandi.

1972 ◽  
Vol 20 (4) ◽  
pp. 225-231
Author(s):  
J.G. Boonman
Keyword(s):  
Adverse Effect ◽  
Seed Production ◽  
Rainy Season ◽  
Seed Set ◽  
Experimental Studies ◽  
Late Season ◽  
Main Adverse Effect ◽  
Setaria Sphacelata ◽  
Seed Crops ◽  
Seed Yields

Effects of date of applying top-dressings of N to early-season and late-season seed crops of Setaria sphacelata cv. Nandi were studied in 4 trials in 1967-71. Highest seed yields were obtained when N was applied as soon as possible after the onset of the rainy season; a delay of 4 weeks reduced yields of pure germinating seed by >60%. Total yields of herbage DM and number of heads were also reduced, but to a lesser extent; the main adverse effect was on seed set/head. In late-season crops, applying N 2 weeks after the earliest possible date proved beneficial in 2 out of 3 years. (Abstract retrieved from CAB Abstracts by CABI’s permission)

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