Search results for " Plasticity"
showing 10 items of 494 documents
Plastic adjustments of biparental care behavior across embryonic development under elevated temperature in a marine ectotherm
2021
Abstract Phenotypic plasticity in parental care investment allows organisms to promptly respond to rapid environmental changes by potentially benefiting offspring survival and thus parental fitness. To date, a knowledge gap exists on whether plasticity in parental care behaviors can mediate responses to climate change in marine ectotherms. Here, we assessed the plasticity of parental care investment under elevated temperatures in a gonochoric marine annelid with biparental care, Ophryotrocha labronica, and investigated its role in maintaining the reproductive success of this species in a warming ocean. We measured the time individuals spent carrying out parental care activities across three…
Morphological adaptation in host races of Tephritis conura
2007
The present study investigates morphological differentiation among host races of the fruit fly Te phritis conura Loew (Diptera: Tephritidae) for two fitness-related traits and whether these traits are host induced or genetically determined. Flies were analyzed from independent sympatric regions, and from one syntopic site where parental host plants [ Cirsium heterophyllum (L.) Hill. and Cirsium oleraceum (L.) Scop. (Cardueae)] and hybrid plants ( C. heterophyllum × C. oleraceum ) co-occur. As both host races may oviposit on hybrid plants and hybrid plants provide an identical environment for larvae of both host races, flies emerging from C. heterophyllum × C. oleraceum hybrids were used to …
Genetic and morphological differentiation in Tephritis bardanae (Diptera: Tephritidae): evidence for host-race formation
2003
The fruit fly Tephritis bardanae infests flower heads of two burdock hosts, Arctium tomentosum and A. minus. Observations suggest host-associated mating and behavioural differences at oviposition indicating host-race status. Previously, flies from each host plant were found to differ slightly in allozyme allele frequencies, but these differences could as well be explained by geographical separation of host plants. In the present study, we explicitly test whether genetic and morphological variance among T. bardanae are explained best by host-plant association or by geographical location, and if this pattern is stable over a 10-year period. Populations of A. tomentosum flies differed signific…
Do avian predators select for seasonal polyphenism in the European map butterfly Araschnia levana (Lepidoptera: Nymphalidae)?
2012
Seasonal polyphenism in animal colour patterns indicates that temporal variation in selection pressures maintains phenotypic plasticity. Spring generation of the polyphenic European map butterfly Araschnia levana has an orange–black fritillary-like pattern whilst individuals of the summer generation are black with white bands across the wings. What selects for the colour difference is unknown. Because predation is a major selection pressure for insect coloration, we first tested whether map butterfly coloration could have a warning function (i.e. whether the butterflies are unpalatable to birds). In a following field experiment with butterfly dummies we tested whether the spring form is bet…
EctoparasiticArgulus coregoni(Crustacea: Branchiura) hedge their bets - studies on egg hatching dynamics
2004
Unpredictability in the temporal availability of susceptible hosts is likely to act as a selection pressure affecting the life history strategies of parasites. In highly variable environments the future of the lineage can be secured by spreading the risk, for example, by producing descendants that differ in their timing of emergence. Counter to this, in predictable environments a single “best-adapted” phenotype is expected. We asked whether ectoparasitic Argulus coregoni egg hatching pattern can be explained as a genetically canalized individual trait; an instance of phenotypic plasticity or bet-hedging. We collected egg clutches laid by individual A. coregoni females in early and late repr…
Molecular-genetic-based contribution to the taxonomy of theAcanthocyclops robustusgroup
2013
Long-standing taxonomic problems involving the Acanthocyclops robustus–vernalis complex of freshwater cyclopoids have not been resolved. After Kiefer's designation of A. robustus Sars as an older synonym of Acanthocycops americanus Marsh, a lot of data indicating their differentiation have been accumulated. To handle this taxonomical problem, representative populations from type localities of the respective taxa and from other European and US sites were analyzed morphologically and genetically using mitochondrial COI and 12S rRNA. Molecular-genetic analysis revealed that the three species described at the end of the nineteenth century: A. robustus, A. americanus and A. vernalis are well-sep…
Life in suspension and its impact on phytoplankton morphology: an homage to Colin S. Reynolds
2020
The amazing morphological diversity of phytoplankton has to be considered an evolutionarily driven compendium of strategies to cope with the strong variability and unpredictability of the pelagic environment. Phytoplankton collects unicellular and colonial photosynthetic organisms adapted to live in apparent suspension in turbulent water masses. Turbulence represents a key driver of phytoplankton dynamics in all aquatic ecosystems and phytoplankton morphological variability is the evolutionary response of this group of photosynthetic organisms to the temporal and spatial scales of variability of turbulence. This paper reviews the existing literature on the effects exerted by turbulence on p…
The multiple slope discontinuity beam element for nonlinear analysis of RC framed structures
2018
The seismic nonlinear response of reinforced concrete structures permits to identify critical zones of an existing structure and to better plan its rehabilitation process. It is obtained by performing finite element analysis using numerical models classifiable into two categories: lumped plasticity models and distributed plasticity models. The present work is devoted to the implementation, in a finite element environment, of an elastoplastic Euler–Bernoulli beam element showing possible slope discontinuities at any position along the beam span, in the framework of a modified lumped plasticity. The differential equation of an Euler–Bernoulli beam element under static loads in presence of mul…
An energy residual-based approach to gradient effects within the mechanics of generalized continua
2012
AbstractGeneralized continua exhibiting gradient effects are addressed through a method grounded on the energy residual (ER)-based gradient theory by the first author and coworkers. A main tool of this theory is the Clausius-Duhem inequality cast in a form differing from the classical one only by a nonstandard extra term, the (nonlocality) ER, required to satisfy the insulation condition (its global value has to vanish or to take a known value). The ER carries in the nonlocality features of the mechanical problem through a strain-like rate field, being the specific nonlocality source, and a concomitant higher-order long-range stress (or microstress) field. The thermodynamic restrictions on …