Search results for "Intraspecific competition"
showing 10 items of 124 documents
Fitness costs of intrinsic competition in two egg parasitoids of a true bug
2015
Intrinsic competition in insect parasitoids occurs when supernumerary larvae develop in the same host as consequence of multiple ovipositions by females of the same species (intra-specific competition) or by females of different species (inter-specific competition). Studies on intrinsic competition have mainly focused on understanding the factors that play a role in the outcome of competition, while fitness-related effects for the parasitoid surviving the competition have been poorly investigated, especially in egg parasitoids. Interestingly, even the winning parasitoid can experience fitness costs due to larval development in a host in which multiple factors have been injected by the ovipo…
Interspecific Social Learning: Novel Preference Can Be Acquired from a Competing Species
2007
SummaryNongenetic transmission of behavioral traits via social learning allows local traditions in humans, and, controversially, in other animals [1–4]. Social learning is usually studied as an intraspecific phenomenon (but see [5–7]). However, other species with some overlap in ecology can be more than merely potential competitors: prior settlement and longer residence can render them preferable sources of information [8]. Socially induced acquisition of choices or preferences capitalizes upon the knowledge of presumably better-informed individuals [9] and should be adaptive under many natural circumstances [10, 11]. Here we show with a field experiment that females of two migrant flycatch…
Interspecific and intraspecific interactions in the monogenean communities of fish: a question of study scale?
2007
SUMMARYMonogenean communities of fish have generally been considered non-interactive as negative interspecific interactions have rarely been reported. Most of the earlier studies on monogenean communities, however, have been conducted not only in systems with relatively low parasite abundances but, more importantly, at study scales where microhabitat-level interactions between the parasites are easily overlooked. We examined the communities of 3 abundant Dactylogyrus (Monogenea) species on the gills of crucian carp (Carassius carassius) by analysing the interactions at the scale of individual gill filaments, where interactions between the species, if any, should most likely take place. Cont…
Genecological and isozyme studies in Senecio vernalis Waldst. & Kit. and S. vulgaris L. var. vulgaris (Asteraceae) from Central Europe and Israel
1995
Summary Genecological evidence and evidence obtained from an isozyme survey suggest a considerable amount of intraspecific differentiation in Senecio vernalis . Plants of this species from Israel were found to differ strikingly from those of C European (German) origin in most of the traits investigated, e.g., in the possession of pronounced seed dormancy, which seems to be governed by a single gene, a shorter life cycle, lack of rosette growth correlated with stem elongation prior to budding, a larger number of smaller capitula with fewer (disc) florets, and an ephemeral habit with plants only flowering soon after the first winter rains. Both accessions achieved a similar reproductive poten…
Direct interference or indirect exploitation? An experimental study of fitness costs of interspecific competition in voles
2002
Studies on competing mammalian species in the past have focused mainly on the competitive exclusion of one species from the preferred habitat of the other. Investigations on effects of competition and coexistence on individual fitness are rare. In this study we were able to measure effects of interspecific competition on major fitness components, using a system with two vole species in asymmetric competition. Survival, reproduction and space use of bank vole Clethrionomys glareolus females were monitored in 32 enclosed populations over four replicates of eight parallel run enclosures. Into half of the enclosures we introduced an additional number of field voles Microtus agrestis, a dominant…
Mating system variation inVeronica(Plantaginaceae): inferences from pollen/ovule ratios and other reproductive traits
2012
The pollen–ovule ratio (P/O) is commonly used to estimate the mode of sexual reproduction in flowering plants. In previous studies, a clear correspondence has been detected between this character and the degree of autogamy. We here investigate variation in this character and its expected correlates in the genus Veronica (Plantaginaceae). Pollen–ovule ratios of 45 species representing eleven percent of all the species in the genus were investigated and compared with results from crossing experiments from previous studies. In addition, multiple populations of 17 of the 45 studied species were sampled and a controlled-environment experiment was conducted to evaluate the extent of intraspecific…
Lymnaea schirazensis, an Overlooked Snail Distorting Fascioliasis Data: Genotype, Phenotype, Ecology, Worldwide Spread, Susceptibility, Applicability
2011
BackgroundLymnaeid snails transmit medical and veterinary important trematodiases, mainly fascioliasis. Vector specificity of fasciolid parasites defines disease distribution and characteristics. Different lymnaeid species appear linked to different transmission and epidemiological patterns. Pronounced susceptibility differences to absolute resistance have been described among lymnaeid populations. When assessing disease characteristics in different endemic areas, unexpected results were obtained in studies on lymnaeid susceptibility to Fasciola. We undertook studies to understand this disease transmission heterogeneity.Methodology/principal findingsA ten-year study in Iran, Egypt, Spain, t…
Variable mode of estrus affects female decision for multiple mating
2011
Investigating patterns of variation in mating strategies may shed light on their evolutionary importance as well as their impact on the strength and shape of sexual selection. Multimale mating (polyandry) and mate choice are intensely studied subjects in the area of sexual selection, but little is known about intraspecific patterns of variation that may respond to dynamic cost-benefit balances. In a laboratory study, we investigated the mating behavior of female bank voles (Myodes glareolus) with distinctly different time and energy budgets: They were either in cycling estrus (CE) or postpartum estrus (PPE) shortly after delivery. Postpartum mating is highly constrained by time and energy d…
Consequences of 3,4-dichloroaniline to guppy populations (Poecilia reticulata): computer simulation and experimental validation
1993
Abstract In order to evaluate the effects of 3,4-dichloroaniline (3,4-DCA), which were detected in a life-cycle test with guppies, on the population level, laboratory guppy populations were examined with regard to regulative parameters. Among the endpoints investigated in life-cycle tests, fecundity was shown to be a sensitive parameter. In laboratory guppy populations, however, intraspecific predation on newborn was the main regulator. Based on these data, a computer simulation programme was used to predict the consequences of 3,4-DCA to guppy populations. A population exposure experiment was conducted to validate the simulation results. The effects detected in the life-cycle test (LOEC: 2…
Comparative phylogeography of the Veronica alpina complex in Europe and North America
2006
The Veronica alpina complex comprises eight species of alpine habitats over a wide range of mountain systems in the Northern Hemisphere. The occurrence of sympatric species in the European and North American mountain systems allowed us not only to investigate the effect of the ice ages on intraspecific phylogeographical patterns and genetic diversity in different continents of the Northern Hemisphere, but also to compare these patterns in closely related species. Plastid DNA trnL-F sequences and AFLP (amplified fragment length polymorphism) fingerprints were used to infer the phylogenetic history of the group and phylogeographical patterns within species. Hybrid origin of tetraploid eastern…