Search results for "photoperiodism"

Melatonin in the seasonal response of the aphid Acyrthosiphon pisum.

2018

Aphids display life cycles largely determined by the photoperiod. During the warm long-day seasons, most aphid species reproduce by viviparous parthenogenesis. The shortening of the photoperiod in autumn induces a switch to sexual reproduction. Males and sexual females mate to produce overwintering resistant eggs. In addition to this full life cycle (holocycle), there are anholocyclic lineages that do not respond to changes in photoperiod and reproduce continuously by parthenogenesis. The molecular or hormonal events that trigger the seasonal response (i.e., induction of the sexual phenotypes) are still unknown. Although circadian synthesis of melatonin is known to play a key role in verteb…

In Vitro Rooting of Capparis spinosa L. as Affected by Genotype and by the Proliferation Method Adopted During the Multiplication Phase

2020

The in vitro rooting of three caper (Capparis spinosa L.) selected biotypes, grown in a commercial orchard on the Sicilian island of Salina (38&deg

2021

Abstract Background Tracing the association between insect cold tolerance and latitudinally and locally varying environmental conditions, as well as key morphological traits and molecular mechanisms, is essential for understanding the processes involved in adaptation. We explored these issues in two closely-related species, Drosophila montana and Drosophila flavomontana, originating from diverse climatic locations across several latitudes on the coastal and mountainous regions of North America. We also investigated the association between sequence variation in one of the key circadian clock genes, vrille, and cold tolerance in both species. Finally, we studied the impact of vrille on fly co…

Inheritance patterns of photoperiodic diapause induction inLeptinotarsa decemlineata

2016

Photoperiod is a reliable indicator of season and an important cue that many insects use for phenological synchronization. Undergoing range expansion insects can face a change in the local photoperiod to which they need to resynchronize. Rapid range expansion can be associated with rapid photoperiodic adaptation, which can be associated with intense selection on strongly heritable polygenic traits. Alternatively, it is proposed that, in insects with an XO sex-determination system, genes with large effect residing on the sex chromosome could drive photoperiodic adaptation because the gene or genes are exposed to selection in the sex carrying only a single X-chromosome. The present study seek…

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, whil…

Multiple paths to cold tolerance: the role of environmental cues, morphological traits and the circadian clock gene vrille

2021

AbstractBackgroundTracing the association between insect cold tolerance and latitudinally and locally varying environmental conditions, as well as key morphological traits and molecular mechanisms, is essential for understanding the processes involved in adaptation. We explored these issues in two closely-related species, Drosophila montana and Drosophila flavomontana, originating from diverse climatic locations across several latitudes on the coastal and mountainous regions of North America. We also investigated the association between sequence variation in one of the key circadian clock genes, vrille, and cold tolerance in both species. Finally, we studied the impact of vrille on fly cold…

Inter- and intra-variability of seed germination traits of Carpobrotus edulis N.E.Br. and its hybrid C. affine acinaciformis.

2018

Invasions by alien Carpobrotus spp. have been recognised as one of the most severe threats to Mediterranean climate coastal ecosystems, and Carpobrotus is considered one of the most widespread invasive alien genera in the Mediterranean Basin. The aims of this study were to characterise seed germination of both C. edulis and its hybrid C. aff. acinaciformis, in terms of photoperiod, temperature and salinity. Inter- and intra-specific variability in the responses to photoperiod (12/12 h light and total darkness), constant temperatures (5, 10, 15, 20, 25 °C) and an alternating temperature regime (25/10 °C), salt stress (0, 125, 250, 500 mm NaCl) and the recovery of seed germination were evalua…

Effects of photoperiod on life-history and thermal stress resistance traits across populations of Drosophila subobscura

2019

Introduction Organisms use environmental cues to match their phenotype with the future availability of resources and environmental conditions. Changes in the magnitude and frequency of environmental cues such as photoperiod and temperature along latitudes can be used by organisms to predict seasonal changes. While the role of temperature variation on the induction of plastic and seasonal responses is well established, the importance of photoperiod for predicting seasonal changes is less explored. Materials and methods Here we studied changes in life‐history and thermal stress resistance traits in Drosophila subobscura in response to variation in photoperiod (6:18, 12:12 and 18:6 light:dark …

Inflexible versus flexible: the influence of temperature and photoperiod on pre- and post-eyespot development time in Libellulidae (Odonata)

2016

Temperature and photoperiod are important environmental parameters for organisms. The present study tests the hypothesis that, during embryogenesis, temperature and photoperiod influence pre- and post-eyespot development time in dragonflies of the family Libellulidae differently. Eggs are used from eight species (five different genera, from Africa/Europe, and lentic/lotic habitat preferences). The eggs are reared under different constant or fluctuating temperature and light conditions. There are no general species-specific degree-days for pre- or the post-eyespot development in these species. In all study species, the variance within and between the treatments of the duration in days and th…

Preparing for Winter: The Transcriptomic Response Associated with Different Day Lengths in Drosophila montana

2016

The work has been supported by a Natural Environment Research Council studentship to D.J.P. and an Academy of Finland grant to M.K. (project 268214). At northern latitudes, the most robust cue for assessing the onset of winter is the shortening of day lengths. Many species use day length as a cue to increase their cold tolerance and/or enter into diapause, but little is known about changes in gene expression that occur under different day lengths. We investigate the gene expression changes associated with differences in light/dark cycles in Drosophila montana, a northerly distributed species with a strong adult photoperiodic reproductive diapause. To examine gene expression changes induced …