scholarly journals Low and annually variable migratory connectivity in a long-distance migrant: Whinchats Saxicola rubetra may show a bet-hedging strategy

Ibis ◽  
2017 ◽  
Vol 159 (4) ◽  
pp. 902-918 ◽  
Author(s):  
Emma Blackburn ◽  
Malcolm Burgess ◽  
Benedictus Freeman ◽  
Alice Risely ◽  
Arin Izang ◽  
...  
Keyword(s):  
Migratory Connectivity ◽  
Bet Hedging ◽  
Long Distance ◽  
Hedging Strategy ◽  
Saxicola Rubetra

scholarly journals Individual reversible plasticity as a genotype‐level bet‐hedging strategy

2021 ◽  
Author(s):  
Thomas R. Haaland ◽  
Jonathan Wright ◽  
Irja I. Ratikainen
Keyword(s):  
Bet Hedging ◽  
Hedging Strategy

scholarly journals Different resource allocation in a Bacillus subtilis population displaying bimodal motility

2021 ◽  
Author(s):  
Simon Syvertsson ◽  
Biwen Wang ◽  
Jojet Staal ◽  
Yongqiang Gao ◽  
Remco Kort ◽  
...  
Keyword(s):  
Gene Expression ◽  
Bacillus Subtilis ◽  
Exponential Growth ◽  
Environmental Changes ◽  
Feedback Regulation ◽  
Bet Hedging ◽  
Hedging Strategy ◽  
Negative Feedback Regulation ◽  
Continuous Increase ◽  
Motile Cells

To cope with sudden changes in their environment, bacteria can use a bet-hedging strategy by dividing the population into cells with different properties. This so-called bimodal or bistable cellular differentiation is generally controlled by positive feedback regulation of transcriptional activators. Due to the continuous increase in cell volume, it is difficult for these activators to reach an activation threshold concentration when cells are growing exponentially. This is one reason why bimodal differentiation is primarily observed from the onset of the stationary phase when exponential growth ceases. An exception is the bimodal induction of motility in Bacillus subtilis, which occurs early during exponential growth. Several mechanisms have been put forward to explain this, including double negative-feedback regulation and the stability of the mRNA molecules involved. In this study, we used fluorescence-assisted cell sorting to compare the transcriptome of motile and non-motile cells and noted that expression of ribosomal genes is lower in motile cells. This was confirmed using an unstable GFP reporter fused to the strong ribosomal rpsD promoter. We propose that the reduction in ribosomal gene expression in motile cells is the result of a diversion of cellular resources to the synthesis of the chemotaxis and motility systems. In agreement, single-cell microscopic analysis showed that motile cells are slightly shorter than non-motile cells, an indication of slower growth. We speculate that this growth rate reduction can contribute to the bimodal induction of motility during exponential growth. IMPORTANCE To cope with sudden environmental changes, bacteria can use a bet-hedging strategy and generate different types of cells within a population, so called bimodal differentiation. For example, a Bacillus subtilis culture can contain both motile and non-motile cells. In this study we compared the gene expression between motile and non-motile cells. It appeared that motile cells express less ribosomes. To confirm this, we constructed a ribosomal promoter fusion that enabled us to measure expression of this promoter in individual cells. This reporter fusion confirmed our initial finding. The re-allocation of cellular resources from ribosome synthesis towards synthesis of the motility apparatus results in a reduction in growth. Interestingly, this growth reduction has been shown to stimulate bimodal differentiation.

scholarly journals Use of stable isotopes (δ2H, δ13C and δ15N) to infer the migratory connectivity of Terek Sandpipers (Xenus cinereus) at stopover sites in the East Asian–Australasian Flyway

2020 ◽  
Vol 13 (1-2) ◽  
pp. 10-17
Author(s):  
Young-Min Moon ◽  
Kwanmok Kim ◽  
Jinhan Kim ◽  
Hwajung Kim ◽  
Jeong-Chil Yoo
Keyword(s):  
Stable Isotopes ◽  
East Asian ◽  
Isotope Analysis ◽  
Light Level ◽  
Conservation Strategy ◽  
Migratory Connectivity ◽  
Long Distance ◽  
Δ13c And Δ15n ◽  
Stopover Sites ◽  
Wintering Areas

Stable isotopes are well documented as effective intrinsic markers to infer migratory connectivity which provides key information for establishing an effective conservation strategy in migratory birds. However, there are few studies using stable isotopes that have been applied to long-distance migratory shorebirds globally and such studies are especially scarce along the East Asian–Australasian Flyway. We used stable isotope analysis (δ2H, δ13C and δ15N) to infer breeding and wintering areas and examine the differences in those values among populations of Terek Sandpipers ( Xenus cinereus) at stopover sites in South Korea. The range of δ2H in feathers sampled from birds caught in the Korean peninsula at spring and autumn migration stopover sites was consistent with them being grown at sites throughout their flyway as confirmed by leg flag resightings of birds on this flyway. The eastern Siberia region from Yakutsk to Norilsk and Chukotka in Russia was inferred as the most probable breeding area of the population. Papua New Guinea in the Melanesia region, Malaysia and Indonesia were identified as the most probable wintering areas. Isotope values of populations at different stopover sites and different seasons were consistent. These results suggest that stable isotopes can be effectively used alongside other existing methods (e.g. ringing, coloured leg flags, light level geolocation, satellite tag telemetry) to infer the migratory connectivity for long-distance migratory shorebird species that occur over many countries and continents.

scholarly journals Migratory connectivity and population-specific migration routes in a long-distance migratory bird

2014 ◽  
Vol 281 (1778) ◽  
pp. 20132897 ◽  
Author(s):  
Christiane Trierweiler ◽  
Raymond H. G. Klaassen ◽  
Rudi H. Drent ◽  
Klaus-Michael Exo ◽  
Jan Komdeur ◽  
...  
Keyword(s):  
Migratory Bird ◽  
Habitat Characteristics ◽  
Sub Saharan Africa ◽  
Migratory Connectivity ◽  
Migration Routes ◽  
Long Distance ◽  
Comprehensive Overview ◽  
Migration System ◽  
Breeding Populations ◽  
Wintering Areas

Knowledge about migratory connectivity, the degree to which individuals from the same breeding site migrate to the same wintering site, is essential to understand processes affecting populations of migrants throughout the annual cycle. Here, we study the migration system of a long-distance migratory bird, the Montagu's harrier Circus pygargus , by tracking individuals from different breeding populations throughout northern Europe. We identified three main migration routes towards wintering areas in sub-Saharan Africa. Wintering areas and migration routes of different breeding populations overlapped, a pattern best described by ‘weak (diffuse) connectivity’. Migratory performance, i.e. timing, duration, distance and speed of migration, was surprisingly similar for the three routes despite differences in habitat characteristics. This study provides, to our knowledge, a first comprehensive overview of the migration system of a Palaearctic-African long-distance migrant. We emphasize the importance of spatial scale (e.g. distances between breeding populations) in defining patterns of connectivity and suggest that knowledge about fundamental aspects determining distribution patterns, such as the among-individual variation in mean migration directions, is required to ultimately understand migratory connectivity. Furthermore, we stress that for conservation purposes it is pivotal to consider wintering areas as well as migration routes and in particular stopover sites.

scholarly journals Costs and benefits of maternally inherited algal symbionts in coral larvae

2017 ◽  
Vol 284 (1857) ◽  
pp. 20170852 ◽  
Author(s):  
Valérie F. Chamberland ◽  
Kelly R. W. Latijnhouwers ◽  
Jef Huisman ◽  
Aaron C. Hartmann ◽  
Mark J. A. Vermeij
Keyword(s):  
Marine Invertebrates ◽  
Costs And Benefits ◽  
Bet Hedging ◽  
Hedging Strategy ◽  
Coral Larvae ◽  
Stony Coral ◽  
Algal Symbionts ◽  
Settlement Success ◽  
Spatio Temporal ◽  
Endosymbiotic Algae

Many marine invertebrates provide their offspring with symbionts. Yet the consequences of maternally inherited symbionts on larval fitness remain largely unexplored. In the stony coral Favia fragum (Esper 1797), mothers produce larvae with highly variable amounts of endosymbiotic algae, and we examined the implications of this variation in symbiont density on the performance of F. fragum larvae under different environmental scenarios. High symbiont densities prolonged the period that larvae actively swam and searched for suitable settlement habitats. Thermal stress reduced survival and settlement success in F. fragum larvae, whereby larvae with high symbiont densities suffered more from non-lethal stress and were five times more likely to die compared with larvae with low symbiont densities. These results show that maternally inherited algal symbionts can be either beneficial or harmful to coral larvae depending on the environmental conditions at hand, and suggest that F. fragum mothers use a bet-hedging strategy to minimize risks associated with spatio-temporal variability in their offspring's environment.

scholarly journals Continent-wide tracking to determine migratory connectivity and tropical habitat associations of a declining aerial insectivore

2012 ◽  
Vol 279 (1749) ◽  
pp. 4901-4906 ◽  
Author(s):  
Kevin C. Fraser ◽  
Bridget J. M. Stutchbury ◽  
Cassandra Silverio ◽  
Patrick M. Kramer ◽  
John Barrow ◽  
...  
Keyword(s):  
North American ◽  
Agricultural Landscape ◽  
Ground Cover ◽  
Light Level ◽  
Agricultural Landscapes ◽  
Habitat Associations ◽  
Migratory Connectivity ◽  
Population Declines ◽  
Long Distance ◽  
Breeding Populations

North American birds that feed on flying insects are experiencing steep population declines, particularly long-distance migratory populations in the northern breeding range. We determine, for the first time, the level of migratory connectivity across the range of a songbird using direct tracking of individuals, and test whether declining northern populations have higher exposure to agricultural landscapes at their non-breeding grounds in South America. We used light-level geolocators to track purple martins, Progne subis , originating from North American breeding populations, coast-to-coast ( n = 95 individuals). We show that breeding populations of the eastern subspecies, P. s. subis , that are separated by ca . 2000 km, nevertheless have almost completely overlapping non-breeding ranges in Brazil. Most (76%) P. s. subis overwintered in northern Brazil near the Amazon River, not in the agricultural landscape of southern Brazil. Individual non-breeding sites had an average of 91 per cent forest and only 4 per cent agricultural ground cover within a 50 km radius, and birds originating from declining northern breeding populations were not more exposed to agricultural landscapes than stable southern breeding populations. Our results show that differences in wintering location and habitat do not explain recent trends in breeding population declines in this species, and instead northern populations may be constrained in their ability to respond to climate change.

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