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Bet hedging

Jonathan P Caulkins
Cannabis legalization is often falsely depicted as a binary choice between status quo prohibition and legalizing production and distribution by (regulated) for-profit industry. There are, however, many more prudent architectures for legalization, such as restricting production and distribution licenses to not-for-profit entities. Wilkins describes how New Zealand applied that concept to gambling machines and proposes a parallel for cannabis legalization. Greater investment in proposing good designs along these lines, including attending to governance structures, would be valuable...
January 11, 2018: International Journal on Drug Policy
Johanna Sunde, Carl Tamario, Petter Tibblin, Per Larsson, Anders Forsman
Environmental heterogeneity is a key determinant of genetic and phenotypic diversity. Stable and homogenous environments tends to result in evolution of specialism and local adaptations, while temporally unpredictable environments may maintain a diversity of specialists, promote generalist strategies, or favour diversified bet hedging strategies. We compared salinity tolerance between two anadromous subpopulations of pike (Esox Lucius) that utilize freshwater spawning sites with different salinity regimes. Eggs from each population were artificially fertilized and incubated in a salinity gradient (0, 3, 5, 7, and 9 psu) using a split-brood design...
January 8, 2018: Scientific Reports
William R Shoemaker, Jay T Lennon
Dormancy is a bet-hedging strategy that allows organisms to persist through conditions that are suboptimal for growth and reproduction by entering a reversible state of reduced metabolic activity. Dormancy allows a population to maintain a reservoir of genetic and phenotypic diversity (i.e., a seed bank) that can contribute to the long-term survival of a population. This strategy can be potentially adaptive and has long been of interest to ecologists and evolutionary biologists. However, comparatively little is known about how dormancy influences the fundamental evolutionary forces of genetic drift, mutation, selection, recombination, and gene flow...
January 2018: Evolutionary Applications
Øystein Nordeide Kielland, Claus Bech, Sigurd Einum
Diversified bet-hedging (DBH) by production of within-genotype phenotypic variance may evolve to maximize fitness in stochastic environments. Bet-hedging is generally associated with parental effects, but phenotypic variation may also develop throughout life via developmental instability (DI). This opens for the possibility of a within-generation mechanism creating DBH during the lifetime of individuals. If so, DI could in fact be a plastic trait itself; if a fluctuating environment indicates uncertainty about future conditions, sensing such fluctuations could trigger DI as a DBH response...
December 2017: Ecology and Evolution
Anne Thonig, Gary Thomas Banta, Benni Winding Hansen, K Emily Knott
Poecilogonous species show variation in developmental mode, with larvae that differ both morphologically and ecologically. The spionid polychaete Pygospio elegans shows variation in developmental mode not only between populations, but also seasonally within populations. We investigated the consequences of this developmental polymorphism on the spatial and seasonal genetic structure of P. elegans at four sites in the Danish Isefjord-Roskilde-Fjord estuary at six time points, from March 2014 until February 2015...
December 2017: Ecology and Evolution
Jan-Ulrich Kreft, Caroline M Plugge, Clara Prats, Johan H J Leveau, Weiwen Zhang, Ferdi L Hellweger
Models are important tools in microbial ecology. They can be used to advance understanding by helping to interpret observations and test hypotheses, and to predict the effects of ecosystem management actions or a different climate. Over the past decades, biological knowledge and ecosystem observations have advanced to the molecular and in particular gene level. However, microbial ecology models have changed less and a current challenge is to make them utilize the knowledge and observations at the genetic level...
2017: Frontiers in Microbiology
Lluis Franch-Gras, Eduardo M García-Roger, Manuel Serra, María José Carmona
Understanding how organisms adaptively respond to environmental fluctuations is a fundamental question in evolutionary biology. The Mediterranean region typically exhibits levels of environmental unpredictability that vary greatly in habitats over small geographical scales. In cyclically parthenogenetic rotifers, clonal proliferation occurs along with occasional bouts of sex. These bouts contribute to the production of diapausing eggs, which allows survival between growing seasons. Here, we studied two diapause-related traits in rotifers using clones from nine Brachionus plicatilis natural populations that vary in the degree of environmental unpredictability...
December 6, 2017: Proceedings. Biological Sciences
Bram Kuijper, Rufus A Johnstone
Maternal effects can provide offspring with reliable information about the environment they are likely to experience, but also offer scope for maternal manipulation of young when interests diverge between parents and offspring. To predict the impact of parent-offspring conflict, we model the evolution of maternal effects on local adaptation of young. We find that parent-offspring conflict strongly influences the stability of maternal effects; moreover, the nature of the disagreement between parents and young predicts how conflict is resolved: when mothers favor less extreme mixtures of phenotypes relative to offspring (i...
December 6, 2017: Evolution; International Journal of Organic Evolution
Rainer Neumann, Nicole Ruppel, Jutta M Schneider
Background: Animal growth is often constrained by unfavourable conditions and divergences from optimal body size can be detrimental to an individual's fitness, particularly in species with determinate growth and a narrow time-frame for life-time reproduction. Growth restriction in early juvenile stages can later be compensated by means of plastic developmental responses, such as adaptive catch-up growth (the compensation of growth deficits through delayed development). Although sex differences regarding the mode and degree of growth compensation have been coherently predicted from sex-specific fitness payoffs, inconsistent results imply a need for further research...
2017: PeerJ
Yukio Yasui, Jin Yoshimura
The origin and maintenance of polyandry is one of the key unresolved questions in evolutionary biology. In particular, extra-pair paternity (EPP) due to polyandry is observed in most (socially-) monogamous female birds and the frequency of EPP is surprisingly high (up to 72% in a clutch on average in some species). Many case-by-case hypotheses have been presented to explain this phenomenon but a ubiquitous explanation is still lacking. One possible general explanation is bet-hedging, which is a strategy to avoid the risk associated to mating with a single unsuitable male and thus to minimize the chances of complete reproductive failure by the female...
January 21, 2018: Journal of Theoretical Biology
Lei Wang, Hong-Ling Wang, Lan Yin, Chang-Yan Tian
BACKGROUND: Dimorphic seeds from Suaeda aralocaspica exhibit different germination behaviors that are thought to be a bet-hedging strategy advantageous in harsh and unpredictable environments. To understand the molecular mechanisms of Suaeda aralocaspica dimorphic seed germination, we applied RNA sequencing and small RNA sequencing for samples collected at three germination stages. RESULTS: A total of 79,414 transcripts were assembled using Trinity, of which 57...
October 19, 2017: BMC Genomics
Caroline M Williams, Gregory J Ragland, Gustavo Betini, Lauren B Buckley, Zachary A Cheviron, Kathleen Donohue, Joe Hereford, Murray M Humphries, Simeon Lisovski, Katie E Marshall, Paul S Schmidt, Kimberly S Sheldon, Øystein Varpe, Marcel E Visser
Seasonality is a critically important aspect of environmental variability, and strongly shapes all aspects of life for organisms living in highly seasonal environments. Seasonality has played a key role in generating biodiversity, and has driven the evolution of extreme physiological adaptations and behaviors such as migration and hibernation. Fluctuating selection pressures on survival and fecundity between summer and winter provide a complex selective landscape, which can be met by a combination of three outcomes of adaptive evolution: genetic polymorphism, phenotypic plasticity, and bet-hedging...
November 1, 2017: Integrative and Comparative Biology
BingKan Xue, Stanislas Leibler
Biological organisms have to cope with stochastic variations in both the external environment and the internal population dynamics. Theoretical studies and laboratory experiments suggest that population diversification could be an effective bet-hedging strategy for adaptation to varying environments. Here we show that bet hedging can also be effective against demographic fluctuations that pose a trade-off between growth and survival for populations even in a constant environment. A species can maximize its overall abundance in the long term by diversifying into coexisting subpopulations of both "fast-growing" and "better-surviving" individuals...
September 8, 2017: Physical Review Letters
Ilan N Rubin, Michael Doebeli
Phenotypic heterogeneity refers to genetically identical individuals that express different phenotypes, even when in the same environment. Traditionally, "bet-hedging" in fluctuating environments is offered as the explanation for the evolution of phenotypic heterogeneity. However, there are an increasing number of examples of microbial populations that display phenotypic heterogeneity in stable environments. Here we present an evolutionary model of phenotypic heterogeneity of microbial metabolism and a resultant theory for the evolution of phenotypic versus genetic specialization...
December 21, 2017: Journal of Theoretical Biology
John Soghigian, Todd Livdahl
Mixed dispersal strategies are a form of bet hedging in which a species or population utilizes different dispersal strategies dependent upon biotic or abiotic conditions. Here we provide an example of a mixed dispersal strategy in the Aedes albopictus / Ascogregarina taiwanensis host/parasite system, wherein upon host emergence, the gregarine parasite is either carried with an adult mosquito leaving the larval habitat, or released back into the larval habitat. We show that the parasite invests a larger proportion of its dispersing (oocyst) life stage into adult female mosquitoes as opposed to adult male mosquitoes at low parasite exposure levels...
2017: PloS One
Lisa N S Shama
Increasing climate variability may pose an even greater risk to species than climate warming because temperature fluctuations can amplify adverse impacts of directional warming on fitness-related traits. Here, the influence of directional warming and increasing climate variability on marine stickleback fish (Gasterosteus aculeatus) offspring size variation was investigated by simulating changes to the mean and variance of ocean temperatures predicted under climate change. Reproductive traits of mothers and offspring size reaction norms across four climate scenarios were examined to assess the roles of standing genetic variation, transgenerational and within-generation plasticity in adaptive potential...
August 21, 2017: Scientific Reports
Vaibhhav Sinha, Akshit Goyal, Sine L Svenningsen, Szabolcs Semsey, Sandeep Krishna
Bacteriophages are the most abundant organisms on the planet and both lytic and temperate phages play key roles as shapers of ecosystems and drivers of bacterial evolution. Temperate phages can choose between (i) lysis: exploiting their bacterial hosts by producing multiple phage particles and releasing them by lysing the host cell, and (ii) lysogeny: establishing a potentially mutually beneficial relationship with the host by integrating their chromosome into the host cell's genome. Temperate phages exhibit lysogeny propensities in the curiously narrow range of 5-15%...
2017: Frontiers in Microbiology
Nick Vallespir Lowery, Luke McNally, William C Ratcliff, Sam P Brown
Bacterial cells, like many other organisms, face a tradeoff between longevity and fecundity. Planktonic cells are fast growing and fragile, while biofilm cells are often slower growing but stress resistant. Here we ask why bacterial lineages invest simultaneously in both fast- and slow-growing types. We develop a population dynamic model of lineage expansion across a patchy environment and find that mixed investment is favored across a broad range of environmental conditions, even when transmission is entirely via biofilm cells...
August 8, 2017: MBio
Rebecca L Scholz, E Peter Greenberg
Many proteobacteria utilize acyl-homoserine lactone quorum-sensing signals. At low population densities, cells produce a basal level of signal, and when sufficient signal has accumulated in the surrounding environment, it binds to its receptor, and quorum-sensing-dependent genes can be activated. A common characteristic of acyl-homoserine lactone quorum sensing is that signal production is positively autoregulated. We have examined the role of positive signal autoregulation in Pseudomonas aeruginosa We compared population responses and individual cell responses in populations of wild-type P...
July 25, 2017: MBio
Pawel Lycus, Kari Lovise Bøthun, Linda Bergaust, James Peele Shapleigh, Lars Reier Bakken, Åsa Frostegård
Present-day knowledge on the regulatory biology of denitrification is based on studies of selected model organisms. These show large variations in their potential contribution to NO2(-), NO, and N2O accumulation, attributed to lack of genes coding for denitrification reductases, but also to variations in their transcriptional regulation, as well as to post-transcriptional phenomena. To validate the relevance of these observations, there is a need to study a wider range of denitrifiers. We designed an isolation protocol that identifies all possible combinations of truncated denitrification chains (NO3(-)/NO2(-)/NO/N2O/N2)...
October 2017: ISME Journal
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