Search results for "Photoperiod"
showing 10 items of 84 documents
Localization of quantitative trait loci for diapause and other photoperiodically regulated life history traits important in adaptation to seasonally …
2015
Seasonally changing environments at high latitudes present great challenges for the reproduction and survival of insects, and photoperiodic cues play an important role in helping them to synchronize their life cycle with prevalent and forthcoming conditions. We have mapped quantitative trait loci (QTL) responsible for the photoperiodic regulation of four life history traits, female reproductive diapause, cold tolerance, egg-to-eclosion development time and juvenile body weight in Drosophila montana strains from different latitudes in Canada and Finland. The F2 progeny of the cross was reared under a single photoperiod (LD cycle 16:8), which the flies from the Canadian population interpret a…
Changes in gene expression linked with adult reproductive diapause in a northern malt fly species: a candidate gene microarray study
2010
Abstract 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…
Characterisation, analysis of expression and localisation of the opsin gene repertoire from the perspective of photoperiodism in the aphid Acyrthosip…
2017
Organisms exhibit a wide range of seasonal responses as adaptions to predictable annual changes in their environment. These changes are originally caused by the effect of the Earth's cycles around the sun and its axial tilt. Examples of seasonal responses include floration, migration, reproduction and diapause. In temperate climate zones, the most robust variable to predict seasons is the length of the day (i.e. the photoperiod). The first step to trigger photoperiodic driven responses involves measuring the duration of the light-dark phases, but the molecular clockwork performing this task is poorly characterized. Photopigments such as opsins are known to participate in light perception, b…
Photoperiod-temperature and neuroblast proliferation-migration in the adult lizard cortex.
1997
The lizard medial cortex (a zone homologous to the mammalian fascia dentata) shows delayed postnatal neurogenesis throughout the lifetime of these animals. Experimental lesioning of this area is followed by neuronal regeneration, a unique phenomenon in the adult amniote telencephalon. The differential effects of temperature and photoperiod on postnatal neurogenetic activity were studied using tritiated thymidine pulses and posterior autoradiography as well as proliferating cell nuclear antigen (PCNA) immunostaining. Long (summer) photoperiods increased the number of proliferating neuroblasts in the ependymal neuroepithelium. Cold (winter) temperature prevented migration of the newly generat…
Identification of a gene overexpressed in aphids reared under short photoperiod.
2003
Most aphids develop a cyclic parthenogenesis life-cycle. After several generations of viviparously produced parthenogenetic females, follows a single annual generation of sexual individuals, usually in autumn, that mate and lay the sexual eggs. Shortening of photoperiod at the end of the summer (together with temperature) is a key factor inducing the sexual response. Currently no genes involved in the cascade of events that lead to the appearance of sexual forms have been reported. After a Differential Display RT-PCR survey performed on Acyrthosiphon pisum aphids, we identified a gene that is overexpressed in aphids reared under short photoperiod conditions that induce sexuality in this spe…
Adaptation and ecological speciation in seasonally varying environments at high latitudes: Drosophila virilis group
2022
Living in high latitudes and altitudes sets specific requirements on species’ ability to forecast seasonal changes and to respond to them in an appropriate way. Adaptation into diverse environmental conditions can also lead to ecological speciation through habitat isolation or by inducing changes in traits that influence assortative mating. In this review, we explain how the unique time-measuring systems of Drosophila virilis group species have enabled the species to occupy high latitudes and how the traits involved in species reproduction and survival exhibit strong linkage with latitudinally varying photoperiodic and climatic conditions. We also describe variation in reproductive barriers…
Mixed support for an alignment between phenotypic plasticity and genetic differentiation in damselfly wing shape
2023
The relationship between genetic differentiation and phenotypic plasticity can provide information on whether plasticity generally facilitates or hinders adaptation to environmental change. Here, we studied wing shape variation in a damselfly (Lestes sponsa) across a latitudinal gradient in Europe that differed in time constraints mediated by photoperiod and temperature. We reared damselflies from northern and southern populations in the laboratory using a reciprocal transplant experiment that simulated time-constrained (i.e. northern) and unconstrained (southern) photoperiods and temperatures. After emergence, adult wing shape was analysed using geometric morphometrics. Wings from individu…
Energy status and its control on embryogenesis of legumes: ATP distribution within Vicia faba embryos is developmentally regulated and correlated wit…
2003
To analyse the energy status of Vicia faba embryos in relation to differentiation processes, we measured ATP concentrations directly in cryosections using a quantitative bioluminescence-based imaging technique. This method provides a quantitative picture of the ATP distribution close to the in vivo situation. ATP concentrations were always highest within the axis. In pre-storage cotyledons, the level was low, but it increased strongly in the course of further development, starting from the abaxial region of cotyledons and moving towards the interior. Greening pattern, chlorophyll distribution and photosynthetic O2 production within embryos temporally and spatially corresponded to the ATP di…
Photosensitive Alternative Splicing of the Circadian Clock Gene timeless Is Population Specific in a Cold-Adapted Fly, Drosophila montana.
2018
To function properly, organisms must adjust their physiology, behavior and metabolism in response to a suite of varying environmental conditions. One of the central regulators of these changes is organisms' internal circadian clock, and recent evidence has suggested that the clock genes are also important in the regulation of seasonal adjustments. In particular, thermosensitive splicing of the core clock gene <i>timeless</i> in a cosmopolitan fly, <i>Drosophila melanogaster</i> , has implicated this gene to be involved in thermal adaptation. To further investigate this link we examined the splicing of <i>timeless</i> in a northern malt fly species, <i&…
Natural selection mediated by seasonal time constraints increases the alignment between evolvability and developmental plasticity
2021
Abstract Phenotypic plasticity can either hinder or promote adaptation to novel environments. Recent studies that have quantified alignments between plasticity, genetic variation, and divergence propose that such alignments may reflect constraints that bias future evolutionary trajectories. Here, we emphasize that such alignments may themselves be a result of natural selection and do not necessarily indicate constraints on adaptation. We estimated developmental plasticity and broad sense genetic covariance matrices (G) among damselfly populations situated along a latitudinal gradient in Europe. Damselflies were reared at photoperiod treatments that simulated the seasonal time constraints ex…