The behavior of sympatric Chilean populations of Drosophila larvae during pupation

The behavioral mechanisms by which the larvae of sympatric Chilean populations of Drosophila melanogaster, D. simulans, D. hydei and D. busckii select pupation sites are described in terms of larval substrate preferences. These species share the same breeding sites in Central Valley of Chile. It is important to investigate larval substrate preferences to pupate in sympatric natural populations of species of Drosophila because such behavior could contribute to the coexistence of the species in the wild. D. busckii larvae preferred humid substrates with a smooth surface to pupate, whereas D. simulans larvae selected humid substrates with a rough surface. Larvae of D. melanogaster chose dry and humid substrates with a rough surface, whereas D. hydei larvae occupied dry substrates with a smooth surface to form puparia. D. melanogaster larvae dug deeper into dry than into humid sand, whereas D. simulans larvae dug more into humid sand. D. busckii larvae pupated in the upper layers of humid and dry sand, and D. hydei larvae dug more into humid than into dry sand. Pupae of the four Drosophila species showed aggregated distributions on the substrates. Larval prepupation behaviors of D. melanogaster, D. simulans, D. hydei and D. busckii could be important to their coexistence in the wild.

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Low Frequency of “Double Molt” of Remiges in Ruddy Ducks Revealed by Stable Isotopes: Implications for Tracking Migratory Waterfowl

The Auk ◽

10.1093/auk/117.1.129 ◽

2000 ◽

Vol 117 (1) ◽

pp. 129-135 ◽

Cited By ~ 2

Author(s):

Keith A. Hobson ◽

Robert B. Brua ◽

William L. Hohman ◽

Len I. Wassenaar

Keyword(s):

Stable Isotopes ◽

Natural Populations ◽

Low Frequency ◽

Population Level ◽

Wintering Grounds ◽

Breeding Sites ◽

Isotopic Analyses ◽

Breeding Grounds ◽

In The Wild ◽

Ruddy Ducks

Abstract Ratios of the stable carbon (δ13C) and hydrogen (δD) isotopes in newly grown remiges of Ruddy Ducks (Oxyura jamaicensis) are influenced by the isotopic character of food types and ambient water. Systematic isotopic foodweb and water differences between coastal wintering grounds and prairie breeding grounds of Ruddy Ducks provide the basis for using isotopic analyses of feathers to trace the location and timing of molt. Anecdotal evidence, based largely on captive birds, suggests that Ruddy Ducks replace their remiges twice each year (once each on the breeding and wintering grounds), but a recent literature analysis indicates that this phenomenon is rare. Thus, we investigated the extent to which a biannual molt of the remiges occurs in the wild and at the population level. We analyzed the stable isotopes of carbon (n = 57 birds) and hydrogen (n = 50 birds) in flight feathers to estimate the prevalence of the so-called “double molt” of remiges in free-living Ruddy Ducks. Our data showed that natural populations of Ruddy Ducks express an overwhelming unimodal distribution of isotope ratios in their remiges, suggesting that they undergo a single molt at or near the breeding grounds. Only 3 to 6 of 50 birds from Manitoba showed isotopic evidence consistent with growing remiges on the wintering grounds. Feathers from Ruddy Ducks harvested during the fall in the Mississippi Flyway had isotopic profiles consistent with growth on northern freshwater breeding sites. Thus, our results confirm that the replacement of remiges twice each year by Ruddy Ducks is rare, and they suggest that this dual stable-isotope technique can be used to infer general molting origins of North American waterfowl.

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An ecological explanation for hyperallometric scaling of reproduction

10.1101/2021.03.12.435090 ◽

2021 ◽

Author(s):

Tomos Potter ◽

Anja Felmy

Keyword(s):

Body Size ◽

Reproductive Output ◽

Resource Competition ◽

Natural Populations ◽

Scaling Exponent ◽

Wild Populations ◽

Wet Season ◽

Size Dependent ◽

In The Wild ◽

The Relationship

AbstractIn wild populations, large individuals have disproportionately higher reproductive output than smaller individuals. We suggest an ecological explanation for this observation: asymmetry within populations in rates of resource assimilation, where greater assimilation causes both increased reproduction and body size. We assessed how the relationship between size and reproduction differs between wild and lab-reared Trinidadian guppies. We show that (i) reproduction increased disproportionately with body size in the wild but not in the lab, where effects of resource competition were eliminated; (ii) in the wild, the scaling exponent was greatest during the wet season, when resource competition is strongest; and (iii) detection of hyperallometric scaling of reproduction is inevitable if individual differences in assimilation are ignored. We propose that variation among individuals in assimilation – caused by size-dependent resource competition, niche expansion, and chance – can explain patterns of hyperallometric scaling of reproduction in natural populations.

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The sources of sex differences in aging in annual fishes

10.1101/2020.08.25.266411 ◽

2020 ◽

Author(s):

Martin Reichard ◽

Radim Blažek ◽

Jakub Žák ◽

Petr Kačer ◽

Oldřich Tomášek ◽

...

Keyword(s):

Sex Differences ◽

Social Environment ◽

Social Factors ◽

Environmental Conditions ◽

Natural Populations ◽

Experimental Results ◽

Survival Difference ◽

Captive Populations ◽

Baseline Mortality ◽

In The Wild

AbstractSex differences in lifespan and aging are widespread among animals, with males usually the shorter-lived sex. Despite extensive research interest, it is unclear how lifespan differences between the sexes are modulated by genetic, environmental and social factors. We combined comparative data from natural populations of annual killifishes with experimental results on replicated captive populations, showing that females consistently outlived males in the wild. This sex-specific survival difference persisted in social environment only in two most aggressive species, and ceased completely when social and physical contacts were prevented. Demographically, neither an earlier start nor faster rate of aging accounted for shorter male lifespans, but increased baseline mortality and the lack of mortality deceleration in the oldest age shortened male lifespan. The sexes did not differ in any measure of functional aging we recorded. Overall, we demonstrate that sex differences in lifespan and aging may be ameliorated by modulating social and environmental conditions.

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REPRODUCTION IN CAGE POPULATIONS OF A POLYMORPHISM REGULARLY OBSERVED IN THE NATURAL POPULATIONS OF DROSOPHILA MELANOGASTER IN FRANCE

Genetics ◽

10.1093/genetics/88.4.755 ◽

1978 ◽

Vol 88 (4) ◽

pp. 755-759

Author(s):

Annie Fleuriet

Keyword(s):

Drosophila Melanogaster ◽

Natural Populations ◽

Rate Of Return ◽

Rapid Rate ◽

Experimental Conditions ◽

Co2 Sensitivity ◽

In The Wild ◽

Strong Forces

ABSTRACT Polymorphism for both alleles of a gene ref(2)P, which is a usual trait of French natural populations of Drosophila melanogaster, can be reproduced in experimental conditions. ref(2)P is a gene for resistance to the hereditary, noncontagious Rhabdovirus α, responsible for CO2 sensitivity in Drosophila melanogaster. The equilibrium frequencies observed in cages are the same as in the wild, whether α virus is present or not. The rapid rate of return to these equilibrium frequencies indicates that strong forces, which remain to be determined, are responsible for the maintenance of this polymorphism.

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Effective boundary conditions for Stokes flow over a rough surface

Journal of Fluid Mechanics ◽

10.1017/s0022112096000511 ◽

1996 ◽

Vol 316 ◽

pp. 223-240 ◽

Cited By ~ 41

Author(s):

Kausik Sarkar ◽

Andrea Prosperetti

Keyword(s):

Rough Surface ◽

Stokes Flow ◽

Smooth Surface ◽

Traction Force ◽

Slip Condition ◽

Partial Slip ◽

Ensemble Averaging ◽

Effective Boundary ◽

Exact Boundary ◽

Effective Boundary Conditions

Ensemble averaging combined with multiple scattering ideas is applied to the Stokes flow over a stochastic rough surface. The surface roughness is modelled by compact protrusions on an underlying smooth surface. It is established that the effect of the roughness on the flow far from the boundary may be represented by replacing the no-slip condition on the exact boundary by a partial slip condition on the smooth surface. An approximate analysis is presented for a sparse distribution of arbitrarily shaped protrusions and explicit numerical results are given for hemispheres. Analogous conclusions for the two-dimensional case are obtained. It is shown that in certain cases a traction force develops on the surface at an angle with the direction of the flow.

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Captive Hill Mynah Gracula religiosa breeding success: potential for bird conservation in Thailand?

Bird Conservation International ◽

10.1017/s0959270905000651 ◽

2005 ◽

Vol 15 (4) ◽

pp. 327-335 ◽

Cited By ~ 3

Author(s):

MANEE ARCHAWARANON

Keyword(s):

Captive Breeding ◽

Natural Populations ◽

Reproductive Behaviour ◽

Free Access ◽

Bird Conservation ◽

Species Survival ◽

Conservation Problem ◽

In Captivity ◽

In The Wild ◽

Nest Materials

Hill Mynah Gracula religiosa is one of the most popular bird pets worldwide due to its ability to mimic diverse sounds, especially human speech. However, Mynahs have rarely been bred in captivity, so nestlings from natural populations are in large demand, resulting in many populations being threatened with extinction. Both subspecies in Thailand, intermedia and religiosa, are costly and desired in the pet market. Captive breeding is one of the most practical strategies to solve a conservation problem of this nature and this report describes a success in breeding Hill Mynahs in captivity. Mated pairs were given free access to food, nest-cavities and nest materials. Reproductive behaviour in captivity was not different from that in the wild, with the exception that breeding occurred throughout the year, even during the non-breeding season for wild populations. Although there are doubts concerning the reintroduction of captive-bred birds and whether successful Hill Mynah breeding in captivity is an economically competitive alternative to poaching, it ensures species survival in captivity as the risk of extinction increases.

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Effects of Friction on Contact of Transverse Ground Surfaces

Journal of Tribology ◽

10.1115/1.2928858 ◽

1994 ◽

Vol 116 (3) ◽

pp. 430-437 ◽

Cited By ~ 5

Author(s):

J. B. Mann ◽

T. N. Farris ◽

S. Chandrasekar

Keyword(s):

Rough Surface ◽

Contact Pressure ◽

Smooth Surface ◽

Bulk Material ◽

Elastic Half Space ◽

Material Surface ◽

Asperity Contact ◽

Hertz Contact ◽

Effective Stresses ◽

Subsurface Stress

The two-dimensional plane-strain sliding contact of a smooth rigid roller on a transverse ground rough surface is analyzed. The rough surface is idealized as an elastic half-space with periodic roughness modeled as cylindrical ridges oriented transverse to the sliding direction. The contact problem is solved using a numerical iterative method in which each asperity contact is treated as a micro-Hertz contact, and the exact treatment of asperity interaction is included. The subsurface stress field is calculated using Westergaard stress functions. The subsequent analysis compares the rough surface stress fields with the corresponding smooth Hertz contact to evaluate the influence of surface roughness and friction on the subsurface stress distributions. The results show that the real area of contact is less than the corresponding smooth surface Hertz contact area, and the magnitude of the actual localized maximum contact pressure is always greater than the corresponding smooth surface contact pressure. The asperity level subsurface effective stresses are greater in magnitude than the maximum subsurface stress due to the macro-Hertz contact for low coefficients of friction, and for high coefficients of friction the maximum effective stresses occur on the bulk material surface.

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The social and ecological costs of an ‘over-extended' phenotype

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2015.2359 ◽

2016 ◽

Vol 283 (1822) ◽

pp. 20152359 ◽

Cited By ~ 6

Author(s):

Lyndon Alexander Jordan ◽

Sean M. Maguire ◽

Hans A. Hofmann ◽

Masanori Kohda

Keyword(s):

Cichlid Fish ◽

Experimental Manipulation ◽

Ecological Interactions ◽

Natural Experiments ◽

Extended Phenotype ◽

Breeding Sites ◽

The Social ◽

In The Wild ◽

Social Policing ◽

Ecological Cost

Extended phenotypes offer a unique opportunity to experimentally manipulate and identify sources of selection acting on traits under natural conditions. The social cichlid fish Neolamprologus multifasciatus builds nests by digging up aquatic snail shells, creating an extended sexual phenotype that is highly amenable to experimental manipulation through addition of extra shells. Here, we find sources of both positive sexual selection and opposing natural selection acting on this trait; augmenting shell nests increases access to mates, but also increases social aggression and predation risk. Increasing the attractiveness of one male also changed social interactions throughout the social network and altered the entire community structure. Manipulated males produced and received more displays from neighbouring females, who also joined augmented male territories at higher rates than unmanipulated groups. However, males in more attractive territories received more aggression from neighbouring males, potentially as a form of social policing. We also detected a significant ecological cost of the ‘over-extended' phenotype; heterospecific predators usurped augmented nests at higher rates, using them as breeding sites and displacing residents. Using these natural experiments, we find that both social and ecological interactions generate clear sources of selection mediating the expression of an extended phenotype in the wild.

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Captive-bred Atlantic salmon released into the wild have fewer offspring than wild-bred fish and decrease population productivity

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2020.1671 ◽

2020 ◽

Vol 287 (1937) ◽

pp. 20201671

Author(s):

Ronan James O'Sullivan ◽

Tutku Aykanat ◽

Susan E. Johnston ◽

Ger Rogan ◽

Russell Poole ◽

...

Keyword(s):

Atlantic Salmon ◽

Natural Populations ◽

Mixed Population ◽

Lifetime Reproductive Success ◽

Wild Relative ◽

Offspring Survival ◽

Wild Populations ◽

Annual Productivity ◽

In The Wild ◽

Analyse Data

The release of captive-bred animals into the wild is commonly practised to restore or supplement wild populations but comes with a suite of ecological and genetic consequences. Vast numbers of hatchery-reared fish are released annually, ostensibly to restore/enhance wild populations or provide greater angling returns. While previous studies have shown that captive-bred fish perform poorly in the wild relative to wild-bred conspecifics, few have measured individual lifetime reproductive success (LRS) and how this affects population productivity. Here, we analyse data on Atlantic salmon from an intensely studied catchment into which varying numbers of captive-bred fish have escaped/been released and potentially bred over several decades. Using a molecular pedigree, we demonstrate that, on average, the LRS of captive-bred individuals was only 36% that of wild-bred individuals. A significant LRS difference remained after excluding individuals that left no surviving offspring, some of which might have simply failed to spawn, consistent with transgenerational effects on offspring survival. The annual productivity of the mixed population (wild-bred plus captive-bred) was lower in years where captive-bred fish comprised a greater fraction of potential spawners. These results bolster previous empirical and theoretical findings that intentional stocking, or non-intentional escapees, threaten, rather than enhance, recipient natural populations.

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Freeze-Thawing Damage Model of New-to-Old Concrete with Different Rough Interfaces

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.405-408.2707 ◽

2013 ◽

Vol 405-408 ◽

pp. 2707-2714 ◽

Cited By ~ 1

Author(s):

Cheng Yi ◽

Su Ling Lai ◽

Hong Guang Zhu ◽

Shi Hong Yan ◽

Jian Xia Liu ◽

...

Keyword(s):

Fractal Dimension ◽

Rough Surface ◽

Smooth Surface ◽

Substrate Surface ◽

Damage Model ◽

Test Results ◽

Two Stage ◽

Second Stage ◽

Rough Substrate ◽

Substrate Surfaces

New-to-old concrete freeze-thawing durability affects the safety and normal service of structure. In this paper, the freeze-thawing resistance of new-to-old concrete with different rough substrate surfaces was studied. The roughness of substrate surface was characterized by fractal dimension. Test results show that freeze-thawing damage of new-to-old concrete has two stage changes: first stage, freeze-thawing damage increases rapidly, mainly caused by the damage of interface; second stage, freeze-thawing damage increases slower, mainly reflects damage of substrate and overlay. Compared with smooth surface, rough surface can significantly improve freeze-thawing resistance of new-to-old concrete. In a certain range, with the increase of fractal dimension, the freeze-thawing resistance improves. When the fractal dimension is beyond the range, the freeze-thawing resistance impairs while the fractal dimension increases. A freeze-thawing damage model applied to new-to-old concrete is proposed, and a good correlation is found between the model and experimental results.

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