Shoaling behaviour in a surface-dwelling and a cave-dwelling population of a barb Garra barreimiae (Cyprinidae, Teleostei)

Polyandry (female multiple mating) can confer important benefits to females, but few studies have considered its potential costs. One such cost may arise through differences in the relatedness of offspring born to females with different mating histories; offspring born to monandrous females are always full siblings, while those produced by polyandrous females may be full or half siblings. These differences may have important consequences for social interactions among offspring. We used artificial insemination in the guppy ( Poecilia reticulata ), a promiscuous live-bearing fish, to evaluate shoaling behaviour in polyandrous and monandrous broods. We combined this information with known parentage data for the polyandrous broods to determine whether sibling relatedness influenced offspring shoaling behaviour. While we detected no effect of mating treatment (polyandry/monandry) on shoaling behaviour, we found that pairs of full siblings spent significantly more time shoaling (and in close proximity) than pairs of half siblings. This latter finding confirms the ability of newborn guppies to distinguish brood mates on the basis of kinship, but also suggests an important and hitherto unrealized potential cost of polyandry: a reduction in within-brood relatedness with potentially important implications for offspring social behaviour.

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First draft genome of loach (Orenectus shuilongensis; Cypriniformes: Nemacheilidae) provide insights into the evolution of cavefish

10.21203/rs.3.rs-192229/v1 ◽

2021 ◽

Author(s):

Zhijin Liu ◽

Xuekun Qian ◽

Ziming Wang ◽

Huamei Wen ◽

Ling Han ◽

...

Keyword(s):

Single Molecule ◽

Genome Assembly ◽

Eye Development ◽

Draft Genome ◽

Evolutionary Process ◽

Integrated Approach ◽

Sequencing Data ◽

Retina Development ◽

Draft Genome Assembly ◽

Surface Dwelling

Abstract BcakgroundLoaches of the superfamily Cobitoidea (Cypriniformes, Nemacheilidae) are small elongated bottom-dwelling freshwater fishes with several barbels near the mouth. The genus Oreonectes with 18 currently recognized species contains representatives for all three key stages of the evolutionary process (a surface-dwelling lifestyle, facultative cave persistence, and permanent cave dwelling). Some Oreonectes species show typical cave dwelling-related traits, such as partial or complete leucism and regression of the eyes, rendering them as suitable study objects of micro-evolution. Genome information of Oreonectes species is therefore an indispensable resource for research into the evolution of cavefishes.ResultsHere we assembled the genome sequence of O. shuilongensis, a surface-dwelling species, using an integrated approach that combined PacBio single-molecule real-time sequencing and Illumina X-ten paired-end sequencing. Based on in total 50.9 Gb of sequencing data, our genome assembly from Canu and Pilon spans approximately 515.64 Mb (estimated coverage of 100 ×), containing 803 contigs with N50 values of 5.58 Mb. 25,247 protein-coding genes were predicted, of which 95.65% have been functionally annotated. We also performed genome re-sequencing of three additional cave-dwelling Oreonectes fishes. Twenty-nine pseudogenes annotated using DAVID showed significant enrichment for the GO terms of “eye development” and “retina development in camera-type eye”. It is presumed that these pseudogenes might lead to eye degeneration of semi/complete cave-dwelling Oreonectes species. Furthermore, Mc1r (melanocortin-1 receptor) is a pseudogenization by a deletion in O. daqikongensis, likely blocking biosynthesis of melanin and leading to the albino phenotype.ConclusionsWe here report the first draft genome assembly of Oreonectes fishes, which is also the first genome reference for Cobitidea fishes. Pseudogenization of genes related to body color and eye development may be responsible for loss of pigmentation and vision deterioration in cave-dwelling species. This genome assembly will contribute to the study of the evolution and adaptation of fishes within Oreonectes and beyond (Cobitidea).

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Exopolysaccharide anchoring creates an extreme resistance to sedimentation

Journal of Bacteriology ◽

10.1128/jb.00023-21 ◽

2021 ◽

Author(s):

Nickolas G. Kessler ◽

David M. Caraballo Delgado ◽

Neel K. Shah ◽

Jeff A. Dickinson ◽

Sean D. Moore

Keyword(s):

Single Species ◽

Adaptive Strategy ◽

Genetic Screens ◽

E Coli ◽

Aqueous Environments ◽

Sedimentation Resistance ◽

Surface Dwelling ◽

Stress Sensing ◽

Response To Temperature ◽

Unusual Phenotype

By evolving strains of E. coli that hyper-resist sedimentation, we discovered an uncharacterized mechanism that bacteria can use to remain in suspension indefinitely without expending energy. This unusual phenotype was traced to the anchoring of long colanic acid polymers (CAP) that project from the cell surface. Although each characterized mutant activated this same mechanism, the genes responsible and the strengths of the phenotypes varied. Mutations in rcsC, lpp, igaA, or the yjbEFGH operon were sufficient to stimulate sedimentation resistance, while mutations altering the cps promoter, cdgI, or yjbF provided phenotypic enhancements. The sedimentation resistances changed in response to temperature, growth phase, and carbon source and each mutant exhibited significantly reduced biofilm formation. We discovered that the degree of colony mucoidy exhibited by these mutants was not related to the degree of Rcs pathways activation or to the amount of CAP that was produced; rather, it was related to the fraction of CAP that was shed as a true exopolysaccharide. Therefore, these and other mutations that activate this phenotype are likely to be absent from genetic screens that relied on centrifugation to harvest bacteria. We also found that this anchored CAP form is not linked to LPS cores and may not be attached to the outer membrane. IMPORTANCE Bacteria can partition in aqueous environments between surface-dwelling, planktonic, sedimentary, and biofilm forms. Residence in each location provides an advantage depending on nutritional and environmental stresses and a community of a single species is often observed to be distributed throughout two or more of these niches. Another adaptive strategy is to produce an extracellular capsule, which provides an environmental shield for the microbe and can allow escape from predators and immune systems. We discovered that bacteria can either shed or stably anchor capsules to dramatically alter their propensity to sediment. The degree to which the bacteria anchor their capsule is controlled by a stress sensing system, suggesting that anchoring may be used as an adaptive response to severe environmental challenges.

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The earliest evidence for dwelling construction in the Upper Palaeolithic of Eastern Europe: a 30,000-year-old surface structure from Mira layer I

Vita Antiqua ◽

10.37098/va-2021-13-43-54 ◽

2021 ◽

pp. 43-54

Author(s):

V.N. Stepanchuk ◽

Keyword(s):

Eastern Europe ◽

Surface Structure ◽

Steppe Zone ◽

East European Plain ◽

Upper Palaeolithic ◽

Interior Space ◽

Radiocarbon Dates ◽

East European ◽

Surface Dwelling ◽

Layer I

The purpose of this article is to present data on the surface structure identified in the upper layer of the Mira site in the Dnieper valley. The occupation of layer I, based on a set of consistent data, constitutes the remains of a seasonal winter camp of Pleistocene horse hunters. Ten available radiocarbon dates place the calibrated age of layer I between 31,000 to 28,000 cal BP. The rapid albeit gentle overlapping of the settlement remains with alluvial sediments ensured that the original settlement and dwelling patterns and their elements survived well. Thanks to this, it is possible to reconstruct some significant aspects of the construction process, as well as details of the arrangement of the dwelling’s interior space. A 30,000-year-old, permanent skeleton cylindrical yaranga type surface construction from Mira layer I is currently representing the oldest dwelling known in the Upper Palaeolithic of Ukraine and a broader context of the steppe zone of the East European plain. Keywords: Upper Palaeolithic, surface dwelling, Eastern Europe

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On the Suggestion that the Secretion from the Metathoracic Scent Glands of A Surface-Dwelling Aquatic Insect, Gerris Najas (De Geer), (Heteroptera; Gerridae) has a Waterproofing Function

Journal of Experimental Biology ◽

10.1242/jeb.57.3.765 ◽

1972 ◽

Vol 57 (3) ◽

pp. 765-769

Author(s):

B. W. STADDON

Keyword(s):

Methyl Alcohol ◽

Aquatic Insect ◽

Surface Forces ◽

Scent Glands ◽

Scent Gland ◽

Surface Dwelling

1. Experiments have been carried out which give no support to the suggestion that the secretion from the metathoracic scent glands of the pond skater Gerris najas has a waterproofing function. 2. The ability of the hair pile to resist wetting by surface forces was determined by treatment with graded solutions of pure methyl alcohol in water. 3. In experiments of up to 7.5 weeks duration it was found that the hydrofuge hair pile of insects with sealed scent gland openings was no less resistant to wetting by surface forces than that of the controls.

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Long-term fasting and realimentation in hypogean and epigean isopods: a proposed adaptive strategy for groundwater organisms

Journal of Experimental Biology ◽

10.1242/jeb.205.14.2079 ◽

2002 ◽

Vol 205 (14) ◽

pp. 2079-2087 ◽

Cited By ~ 2

Author(s):

Frédéric Hervant ◽

David Renault

Keyword(s):

Metabolic Response ◽

Large Body ◽

Adaptive Strategy ◽

Energy System ◽

Adaptive Responses ◽

Rapid Restoration ◽

Surface Dwelling ◽

Unpredictable Environment ◽

Lipid Stores

SUMMARYThe effects of long-term fasting and subsequent refeeding on digestive physiology and energy metabolism were investigated in a subterranean aquatic crustacean, Stenasellus virei, and in a morphologically similar surface-dwelling species, Asellus aquaticus. Metabolic response to food deprivation was monophasic in A. aquaticus, with an immediate,large decrease in all energy reserves. In contrast, S. vireidisplayed three successive periods of phosphageno-glucidic, lipidic and,finally, proteo-lipidic-dominant catabolism over the course of the nutritional stress. To represent the responses of subterranean crustaceans to food stress and renutrition, a sequential energy strategy was hypothesized, suggesting that four successive phases (called stress, transition, adaptation and recovery) can be distinguished. Based on these results, a general adaptive strategy for groundwater organisms was proposed. Their remarkable resistance to long-term fasting may be partly explained by (1) a depressed metabolism,during which they mainly subsist on lipid stores, (2) a prolonged state of glycogen- and protein-sparing, (3) low energetic requirements and (4) large body stores. In addition, these groundwater species displayed high recovery abilities during refeeding, showing an optimal utilization of available food and a rapid restoration of their body reserves. These adaptive responses might be considered for numerous subterranean organisms as an efficient energy-saving strategy in a harsh and unpredictable environment where fasting(and/or hypoxic) periods of variable duration alternate with sporadic feeding events (and/or normoxic periods). Therefore, food-limited and/or hypoxia-tolerant groundwater species appear to be good examples of animals representing a low-energy system.

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