Search results for "Systematics"
showing 10 items of 6702 documents
Influence of temperature and photoperiod on embryonic development in the dragonflySympetrum striolatum(Odonata: Libellulidae)
2015
Temperature and photoperiod play major roles in insect ecology. Many insect species have fixed degree-days for embryogenesis, with minimum and maximum temperature thresholds for egg and larval development and hatching. Often, photoperiodic changes trigger the transfer into the next life-cycle stadium. However, it is not known whether this distinct pattern also exist in a species with a high level of phenotypic plasticity in life-history traits. In the present study, eggs of the dragonfly Sympetrum striolatum Charpentier (Odonata: Libellulidae) are reared under different constant and fluctuating temperatures and photoperiodic conditions in several laboratory and field experiments. In general…
2021
Interactions between organisms and their environments are central to how biological diversity arises and how natural populations and ecosystems respond to environmental change. These interactions involve processes by which phenotypes are affected by or respond to external conditions (e.g., via phenotypic plasticity or natural selection) as well as processes by which organisms reciprocally interact with the environment (e.g., via eco-evolutionary feedbacks). Organism-environment interactions can be highly dynamic and operate on different hierarchical levels, from genes and phenotypes to populations, communities, and ecosystems. Therefore, the study of organism-environment interactions requir…
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…
Regulation of pteridine biosynthesis and aromatic amino acid hydroxylation in Drosophila melanogaster
1989
The relationship between high dietary levels of aromatic amino acid and regulation of pteridines in Drosophila eyes was examined by measuring changes in pool levels of six pterins in the wild type and mutants and amino acid pool levels in flies that carry mutations for pteridine biosynthesis. The effect upon relative viability and developmental times was also analyzed; relative viability was affected by L-phenylalanine, L-tryptophan, and L-tyrosine in decreasing order and the D-amino acids had little or no effect. The changes in concentration of biopterin, dihydrobiopterin, pterin, sepiapterin, drosopterins, and isoxanthopterin showed a characteristic pattern of increased and/or decreased a…
Interkalarbl�tter beiPedicularis L.
1967
Pedicularis besitzt wie einige andere Mitglieder der TribusPedicularieae (Scrophulariaceae) sogenannte Interkalarblatter, frondose Deckblatter an der Basis der Floreszenz, die in ihrer Achsel mehr oder minder weit ruckgebildete, oft auf primordialer Stufe sistierte Bluten bergen. Die durch sie gekennzeichnete Hemmzone der Floreszenz kann bis zur Laubblattrosette der Pflanze hinabreichen. Ihre Gegenwart darf in taxonomischer Hinsicht nicht vernachlassigt werden. Die basipetale Hemmung der Bluten kann eine basipetale („zentrifugale“) Aufbluhfolge vortauschen.