Search results for "diapause"
showing 10 items of 78 documents
Species size affects hatching response to different temperature regimes in a rotifer cryptic species complex
2013
The strategy of decreasing size with increasing temperature known as Bergmann’s rule operates at geographic scale and in spite of extensive studies still presents a puzzle to researches. The aim of this work was to verify whether patterns of diapausing egg hatching of closely related species are consistent with the expectations from Bergmann’s rule. In a laboratory study of the cryptic species complex of the rotifer Brachionus plicatilis, the response to temperature (17.5, 22.5, and 25.0 °C) of diapausing eggs collected in a pond where the three tested species coexist was assessed by (1) the number of hatchlings emerging or (2) the time needed to hatch. Our results show that the response to…
Nietoperze Chiroptera: estywacja, hibernacja, torpor
2021
Wahania temperatury otoczenia i obniżona wilgotność powodują u wielu zwierząt, w t u nietoperzy, stres fizjologiczny. Jego następstwem jest spadęk temperatury ciała, czyli hipotermia adaptacyjna. c aktywacja mechanizmu odrętwienia. Stany odrętwienia mogą być wywoływane przez różne czynniki: najcz ęście . to zmiany temperatury, brak pożywienia, światła i fotoperiodyzm, poziom tlenu lub dwutlenku węgla w organizn Minimalizacji ulega także wrażliwość osobnika na bodźce zewnętrzne. Stan odrętwienia u nietoperzy może podzielić na podkategońe. Wyróżniamy takie stany aktywności sezonowych zwierząt, jak: hibernacja, estywa torpor. Zjawisko heterotermii dotyczy wszystkich gatunków nietoperzy, które …
Respostas e adaptações de comunidades de colêmbolos (Hexapoda: Collembola) a condições de inundação e hipoxia
2009
Standard ecological methods (pitfall traps, trunk eclectors and soil cores) were used to evaluate collembolan community responses to different flooding intensities. Three sites of a floodplain habitat near Mainz, Germany, with different flooding regimes were investigated. The structures of collembolan communities are markedly different depending on flooding intensity. Sites more affected by flooding are dominated by hygrophilic and hygrotolerant species, whereas the hardwood floodplain is dominated by mesophilic species. The survival strategies of the hygrophilic and hygrotolerant species include egg diapause and passive drifting. The physiological adaptations to hypoxic conditions of sever…
Measuring the potential for growth in populations investing in diapause
2014
AbstractThe intrinsic rate of population increase (r) is a common performance measure in many ecological and evolutionary studies. However, in life cycles with diapause investment resources are split into a short-term (current population growth) and a long-term (population survival through periods of unsuitable habitat conditions) component, which complicates the use of r as a single performance measure. Here we propose a new measure that integrates both performance components into a single parameter, the potential intrinsic growth rate, rpot. This is the rate of increase that a population/genotype would have if no investment in diapausing stages would occur. We show that rpot can be comput…
Selection of low investment in sex in a cyclically parthenogenetic rotifer
2009
Cyclical parthenogens, which combine asexual and sexual reproduction, are good models for research into the ecological and population processes affecting the evolutionary maintenance of sex. Sex in cyclically parthenogenetic rotifers is necessary for diapausing egg production, which is essential to survive adverse conditions between planktonic growing seasons. However, within a planktonic season sexual reproduction prevents clonal proliferation. Hence, clones with a low propensity for sex should be selected, becoming dominant in the population as the growing season progresses. In this context, we studied the dynamics of the heritable variation in propensity for sexual reproduction among clo…
Responses in metabolic rate to changes in temperature in diapausing Colorado potato beetleLeptinotarsa decemlineatafrom three European populations
2015
Many insects survive adverse periods in seasonal environments by entering diapause, a deep resting stage, during which energy consumption is typically low and gas exchange is in the form of a discontinuous gas exchange cycle (DGC). Because insects in high-latitude environments are severely time constrained during summer, an effective diapause termination with careful regulation of metabolic rate is important. The present study examines whether diapausing Colorado potato beetles Leptinotarsa decemlineataSay originating from three latitudinally different regions in Europe differ in their quantitative or qualitative gas exchange patterns in response to an increasing temperature. Overall produc…
Involvement of circadian oscillation(s) in the photoperiodic time measurement and the induction of reproductive diapause in a northern Drosophila spe…
2013
An ability to predict forthcoming changes in environmental conditions and get prepared for them in advance is crucial for the survival and reproduction of organisms living in a seasonally changing environment. We have studied the possible involvement of circadian oscillator(s) in the photoperiodic timer controlling seasonal responses by tracing Drosophila montana females' diapause induction in constant darkness and in a classical Nanda-Hamner experiment. Nearly all females developed ovaries in continuous darkness, which shows the direct development to be their default developmental pathway in the absence of photoperiods. In Nanda-Hamner experiment the females' diapause incidence was close t…
Nanda-Hamner Curves Show Huge Latitudinal Variation but No Circadian Components in Drosophila Montana Photoperiodism
2021
Insect species with a wide distribution offer a great opportunity to trace latitudinal variation in the photoperiodic regulation of traits important in reproduction and stress tolerances. We measured this variation in the photoperiodic time-measuring system underlying reproductive diapause in Drosophila montana, using a Nanda-Hamner (NH) protocol. None of the study strains showed diel rhythmicity in female diapause proportions under a constant day length (12 h) and varying night lengths in photoperiods ranging from 16 to 84 h at 16°C. In the northernmost strains (above 55°N), nearly all females entered diapause under all photoperiods and about half of them even in continuous darkness, while…
Changes in gene expression linked with adult reproductive diapause in a northern malt fly species: a candidate gene microarray study
2010
Background: Insect diapause is an important biological process which involves many life-history parameters important for survival and reproductive fitness at both individual and population level. Drosophila montana, a species of D. virilis group, has a profound photoperiodic reproductive diapause that enables the adult flies to survive through the harsh winter conditions of high latitudes and altitudes. We created a custom-made microarray for D. montana with 101 genes known to affect traits important in diapause, photoperiodism, reproductive behaviour, circadian clock and stress tolerance in model Drosophila species. This array gave us a chance to filter out genes showing expression changes…
Responses and adaptations of collembolan communities (Hexapoda: Collembola) to flooding and hypoxic conditions
2009
Standard ecological methods (pitfall traps, trunk eclectors and soil cores) were used to evaluate collembolan community responses to different flooding intensities. Three sites of a floodplain habitat near Mainz, Germany, with different flooding regimes were investigated. The structures of collembolan communities are markedly different depending on flooding intensity. Sites more affected by flooding are dominated by hygrophilic and hygrotolerant species, whereas the hardwood floodplain is dominated by mesophilic species. The survival strategies of the hygrophilic and hygrotolerant species include egg diapause and passive drifting. The physiological adaptations to hypoxic conditions of sever…