Search results for "life stage"
showing 10 items of 32 documents
Evaluating responses to temperature during pre-metamorphosis and carry-over effects at post-metamorphosis in the wood tiger moth (Arctia plantaginis)
2019
Insect metamorphosis is one of the most recognized processes delimiting transitions between phenotypes. It has been traditionally postulated as an adaptive process decoupling traits between life stages, allowing evolutionary independence of pre- and post-metamorphic phenotypes. However, the degree of autonomy between these life stages varies depending on the species and has not been studied in detail over multiple traits simultaneously. Here, we reared full-sib larvae of the warningly coloured wood tiger moth ( Arctia plantaginis ) in different temperatures and examined their responses for phenotypic (melanization change, number of moults), gene expression (RNA-seq and qPCR of candidate ge…
Occurrence of Two-Year Cyclicity, “Saw-Blade Fluctuation”, in Vendace Populations in Finland
2021
The tendency towards two-year cyclicity is considered typical of many Fennoscandian vendace populations, especially in fluctuation of recruitment, based on time series of individual lakes. We used two robust indicators to identify and quantify two-year cycles in vendace population proxy time series at different life-stages — spawning stock biomass (SB), density of newly hatched larvae (LD) and recruitment (REC) — from 22 Finnish lakes. Then we applied Fisher’s meta-analytical test to assess the adequacy of the evidence to support the hypothesis that vendace population dynam-ics include two-year cyclicity. The results supported this hypothesis for RECbut not for SB or LD. Yet, the indicators…
Condition-dependent skipped spawning in anadromous brown trout (Salmo trutta)
2018
Repeat spawners of anadromous salmonids may contribute significantly to population resilience by providing multiple cohorts to both seawater and freshwater life stages. In this study, winter survival of sea trout (Salmo trutta Linnaeus, 1758) post spawners (kelts) was 89%. Sea survival increased linearly with female length with a return probability between 30% and 50%, whereas males attained a maximum return probability of 60% at 520 mm. Of the returning sea trout, 40% skipped spawning and they had significantly lower condition factor as kelts compared with those who returned after one summer. These results suggest that sex-specific differences in individual post-spawning growth–survival t…
Diet and trophic niche of the invasive signal crayfish in the first invaded Italian stream ecosystem.
2021
The occurrence of the signal crayfsh Pacifastacus leniusculus in the Valla Stream was the frst established population of this invasive species recorded in an Italian stream ecosystem. We evaluated the seasonality of diet and trophic niche of invasive signal crayfsh in order to estimate the ecological role and efects on native communities of the stream ecosystem. We studied the diferences in food source use between sexes, life stages and seasons using carbon and nitrogen stable isotope analyses. To supplement stable isotope analyses, we evaluated food source usage using traditional stomach content analysis. We tested the hypothesis that juveniles have a diferent diet, showing diferent trophi…
Differential impact of marine debris ingestion during ontogenetic dietary shift of green turtles in Uruguayan waters
2018
Anthropogenic debris ingestion has been reported for green turtles in all their life stages worldwide. The aim of the present study is to evaluate the marine debris ingestion by green turtles stranded in Uruguayan coast between 2005 and 2013. Debris items were categorized and quantified by frequency of occurrence, relative weight, volume and number of items. A total of 96 dead stranded turtles were analyzed and 70% presented debris in their guts. The majority of debris found were plastic, being hard plastics the most abundant in weight. We found no differences in debris ingestion in stranded turtles a long the Uruguayan coast. However we detected a negative correlation between the presence …
The shoot concept of the flower: Still up to date?
2016
Abstract The shoot concept of the flower suggests that flowers correspond to vegetative short-shoots except the fact that their lateral appendages are floral and not vegetative leaves. However, in view of the different properties of vegetative and flower meristems, this concept should be questioned. Differential meristem activity resulting in tubes, hypanthia and inferior ovaries, continuous meristem expansion providing space for stamen fascicles and additional structures and the process of (repeated) fractionation using a given space completely, are characteristics of flower meristems hardly explainable with the shoot concept. Linking instead flower development with recent findings in mole…
Heat hardening capacity in Drosophila melanogaster is life stage-specific and juveniles show the highest plasticity
2019
Variations in stress resistance and adaptive plastic responses during ontogeny have rarely been addressed, despite the possibility that differences between life stages can affect species' range margins and thermal tolerance. Here, we assessed the thermal sensitivity and hardening capacity of Drosophila melanogaster across developmental stages from larval to the adult stage. We observed strong differences between life stages in heat resistance, with adults being most heat resistant followed by puparia , pupae and larvae . The impact of heat hardening (1 h at 35°C) on heat resistance changed during ontogeny, with the highest positive effect of hardening observed in puparia and pupae and the …
Antipredator strategies of pupae: how to avoid predation in an immobile life stage?
2019
Antipredator strategies of the pupal stage in insects have received little attention in comparison to larval or adult stages. This is despite the fact that predation risk can be high during the pupal stage, making it a critical stage for subsequent fitness. The immobile pupae are not, however, defenceless; a wide range of antipredator strategies have evolved against invertebrate and vertebrate predators. The most common strategy seems to be ‘avoiding encounters with predators' by actively hiding in vegetation and soil or via cryptic coloration and masquerade. Pupae have also evolved behavioural and secondary defences such as defensive toxins, physical defences or deimatic movements and soun…
Small pelagic fish in the new millennium: A bottom-up view of global research effort
2021
The present review is an outcome of discussions at the ICES-PICES Symposium on Drivers of Dynamics of Small Pelagic Fish convened in Victoria, B.C., Canada in spring 2017.-- This review is a first contribution of a new international Working Group on Small Pelagic Fish started jointly by ICES (WGSPF) and PICES (WG43) to continue world-wide collaboration to advance knowledge on the drivers of populations of SPF.
The close link between the fetal programming imprinting and neurodegeneration in adulthood: The key role of “hemogenic endothelium” programming
2021
The research on neurodegenerative diseases (NeuroDegD) has been traditionally focused on later life stages. There is now an increasing evidence, that they may be programmed during early development. Here, we propose that NeuroDegD are the result of the complex process of imprinting on fetal hemogenic endothelium, from which the microglial cells make to origin. The central role of placenta and epigenetic mechanisms (methylation of DNA, histone modifications and regulation by non-coding RNAs) in mediating the short and long-term effects has been also described. Precisely, it reports their role in impacting plasticity and memory of microglial cells. In addition, we also underline the necessity…