Search results for "fertility"
showing 10 items of 629 documents
Larval intraspecific competition for food in the European grapevine moth Lobesia botrana.
2014
AbstractEffective pest management with lower amounts of pesticides relies on accurate prediction of insect pest growth rates. Knowledge of the factors governing this trait and the resulting fitness of individuals is thus necessary to refine predictions and make suitable decisions in crop protection. The European grapevine moth, Lobesia botrana, the major pest of grapes in Europe, is responsible for huge economic losses. Larvae very rarely leave the grape bunch on which they were oviposited and thus cannot avoid intraspecific competition. In this study, we determined the impact of intraspecific competition during the larval stage on development and adult fitness in this species. This was tes…
Negative frequency-dependent selection of sexually antagonistic alleles in Myodes glareolus.
2011
Sexually antagonistic genetic variation, where optimal values of traits are sex-dependent, is known to slow the loss of genetic variance associated with directional selection on fitness-related traits. However, sexual antagonism alone is not sufficient to maintain variation indefinitely. Selection of rare forms within the sexes can help to conserve genotypic diversity. We combined theoretical models and a field experiment with Myodes glareolus to show that negative frequency-dependent selection on male dominance maintains variation in sexually antagonistic alleles. In our experiment, high-dominance male bank voles were found to have low-fecundity sisters, and vice versa. These results show …
Relationship between maternal transfer of immunity and mother fecundity in an insect.
2012
Trans-generational immune priming (TGIP) corresponds to the plastic adjustment of offspring immunity as a result of maternal immune experience. TGIP is expected to improve mother's fitness by improving offspring individual performance in an environment where parasitism becomes more prevalent. However, it was recently demonstrated that maternal transfer of immunity to the offspring is costly for immune-challenged female insects. Thus, these females might not provide immune protection to all their offspring because of the inherent cost of other fitness-related traits. Females are therefore expected to adjust their investment to individual offspring immune protection in ways that maximize the…
Prolonged diapause has sex-specific fertility and fitness costs
2019
AbstractDiapause in seasonal environments allows insects to survive adverse seasons. However, individuals can sometimes enter a prolonged diapause for more than a year, and also skip favourable seasons, which can bring additional costs through e.g. loss of metabolic resources. At the same time, prolonged diapause can be beneficial if it allows individuals to have a risk-spreading strategy to skip potentially suboptimal breeding seasons. We studied if prolonged diapause (2-year diapause) negatively affects the fertility and fitness of female and male Colorado potato beetles (Leptinotarsa decemlineata) compared to control (1-year diapause) beetles. We also tested the parental effects on the s…
Morphogenetic modifications induced by Pseudomonas fluorescens A6RI and Glomus mosseae BEG12 in the root system of tomato differ according to plant g…
2002
Summary • The ability of fluorescent pseudomonads and glomalean fungi to promote plant growth has been reported many times. However, little is known of their effects on root morphogenesis. Growth and root morphogenesis were compared in tomato ( Lycopersicon esculentum ) plants inoculated or not with a model strain of Pseudomonas fluorescens (A6RI) or with the arbuscular mycorrhizal fungus Glomus mosseae (BEG12). • Plants were cultivated in a sandy-loam soil mixed with sand at two different ratios (2 : 1 and 1 : 2), in gnotobiotic conditions. Plant growth was evaluated by measuring root and shoot fresh weight, and various morphometric parameters were compared. • Growth of control plants was …
Long-term mineral fertiliser use and maize residue incorporation do not compensate for carbon and nutrient losses from a Ferralsol under continuous m…
2015
9 pages; International audience; It has been repeatedly argued that mineral fertiliser application combined with in situ retention of crop residue biomass can sustain long-term productivity of West African soils. Using 20-year experimental data from southern Togo, a biannual rainfall area, we analysed the effect of two rates of mineral NPK fertiliser application to maize–cotton rotation on the long-term dynamics of soil C and nutrient contents, as compared with two control treatments. Mineral fertiliser treatments consisted of application to both maize (first season) and cotton (second season) the research-recommended NPK rates (Fertiliser-RR) and 1.5 times these rates (Fertiliser-1.5 RR). …
Sexually extravagant males age more rapidly
2011
Evolutionary theories of ageing posit that increased reproductive investment occurs at the expense of physiological declines in later life. Males typically invest heavily in costly sexual ornaments and behaviour, but evidence that the expression of these traits can cause senescence is lacking. Long-lived houbara bustards (Chlamydotis undulata) engage in extravagant sexual displays to attract mates and here we show that males investing most in these displays experience a rapid senescent deterioration of spermatogenic function at a younger age. This effect is sufficiently large that the expected links between male showiness and fertility reverse in later life, despite showy males continuing t…
Parasitism and queen presence interactively shape worker behaviour and fertility in an ant host
2019
Parasites with complex life cycles regularly alter host traits in their own interest. In social hosts, phenotypic alterations induced by parasites can also affect uninfected group members. The tapeworm Anomotaenia brevis uses Temnothorax nylanderi ants as intermediate hosts, reducing host activity and behavioural repertoire, but increasing life span. Uninfected nestmates are less active and less aggressive and suffer from higher mortality. Next to parasites, the social environment, such as the queen, influences worker behaviour, reproduction and longevity. Here, we studied how tapeworm parasitism interacts with the queen to affect the behaviour and reproductive potential of ant workers. We …
Soil functional indicators in a mountain forest-rangeland mosaic of northern Iran
2021
Abstract Soil plays an essential role in providing ecosystem services, especially in mountain ecosystems which are often considered as fragile and sensitive systems and commonly consist of a mosaic of forest and rangeland plant communities. The relationship between above-ground plant cover and the properties of soil organic and mineral layers in mountain areas are rarely studied. This research aimed to assess the effect of different land covers (i.e. forest, forest-rangeland ecotone, and rangeland) on soil functional indicators, i.e. fertility and biological activities, in the Hyrcanian region of northern Iran. We hypothesized that (i) the presence of tree cover enhances soil fertility and …
Factors influencing infection patterns of trophically transmitted parasites among a fish community: host diet, host-parasite compatibility or both?
2011
20 pages; International audience; Parasite infection patterns were compared with the occurrence of their intermediate hosts in the diet of nine sympatric fish species in a New Zealand lake. Stomach contents and infection levels of three gastrointestinal helminth species were examined from the entire fish community. The results highlighted some links between fish host diet and the flow of trophically transmitted helminths. Stomach contents indicated that all but one fish species were exposed to these helminths through their diet. Host feeding behaviour best explained infection patterns of the trematode Coitocaecum parvum among the fish community. Infection levels of the nematode Hedruris spi…