Search results for "Body Size"
showing 10 items of 205 documents
Body size variability across habitats in the Brachionus plicatilis cryptic species complex
2020
AbstractThe body size response to temperature is one of the most recognizable but still poorly understood ecological phenomena. Other covarying environmental factors are frequently invoked as either affecting the strength of that response or even driving this pattern. We tested the body size response in five species representing the Brachionus plicatilis cryptic species complex, inhabiting 10 brackish ponds with different environmental characteristics. Principal Component Analysis selected salinity and oxygen concentration as the most important factors, while temperature and pH were less influential in explaining variation of limnological parameters. Path analysis showed a positive interclo…
Knowing the Risk: Crickets Distinguish between Spider Predators of Different Size and Commonness
2013
Predators unintentionally release chemical and other cues into their environment that can be used by prey to assess predator presence. Prey organisms can therefore perform specific antipredator behavior to reduce predation risk, which can strongly shape the outcome of trophic interactions. In contrast to aquatic systems, studies on cue-driven antipredator behavior in terrestrial arthropods cover only few species to date. Here, we investigated occurrence and strength of antipredator behavior of the wood cricket Nemobius sylvestris toward cues of 14 syntopic spider species that are potential predators of wood crickets. We used two different behavioral arena experiments to investigate the infl…
Starvation endurance in the antTemnothorax nylanderidepends on group size, body size and access to larvae
2013
Social interactions in animal groups can buffer environmental stress and may enhance survival under unfavourable conditions. In the present study, the impact on starvation endurance of social group, access to larvae and cold shock is studied in the ant Temnothorax nylanderi Forster. Resource sharing is expected to lead to grouped workers surviving longer than isolated ones. Access to larvae may increase longevity if larvae serve as food, or may interfere with survival if they induce caring behaviour in workers. Cold shock serves as a stress factor and a negative influence on survival is expected. The results show that isolated workers have a shorter lifespan than grouped workers, which in t…
Robust estimation and inference for bivariate line-fitting in allometry.
2011
In allometry, bivariate techniques related to principal component analysis are often used in place of linear regression, and primary interest is in making inferences about the slope. We demonstrate that the current inferential methods are not robust to bivariate contamination, and consider four robust alternatives to the current methods -- a novel sandwich estimator approach, using robust covariance matrices derived via an influence function approach, Huber's M-estimator and the fast-and-robust bootstrap. Simulations demonstrate that Huber's M-estimators are highly efficient and robust against bivariate contamination, and when combined with the fast-and-robust bootstrap, we can make accurat…
Motor learning and body size within an insect brain computational model
2014
Nowadays modeling insect brains is also an important source of inspiration to develop learning architectures and control algorithms for applications on autonomous walking robots. Within the insect brain two important neuropiles received a lot of attention: the mushroom bodies (MBs) and the central complex (CX). Recent research activities considered the MBs as a unique architecture where different behavioural functions can be found. MBs are well known in bees and flies for their role in performing associative learning and memory in odor conditioning experiments [4]. They are also involved in the processing of multiple sensory modalities including visual tasks [3], different forms of learning…
Subsistence strategies throughout the African Middle Pleistocene: Faunal evidence for behavioral change and continuity across the Earlier to Middle S…
2018
Abstract The African Middle Pleistocene (781–126 ka) is a key period for human evolution, witnessing both the origin of the modern human lineage and the lithic turnover from Earlier Stone Age (ESA) Acheulean bifacial tools to Middle Stone Age (MSA) prepared core and point technologies. This ESA/MSA transition is interpreted as representing changing landscape use with greater foraging distances and more active hunting strategies. So far, these behavioral inferences are mainly based on the extensive stone tool record, with only a minor role for site-based and regional faunal studies. To provide additional insights into these behavioral changes, this paper details a pan-African metastudy of 63…
Large body size variation is linked to low communication success in tandem running ants
2019
AbstractDiversity in animal groups is often assumed to increase group performance. In insect colonies, genetic, behavioral and morphological variation among workers can improve colony functioning and resilience. However, it has been hypothesized that during communication processes, differences between workers, e.g. in body size, could also have negative effects. Tandem running is a common recruitment strategy in ants and allows a leader to guide a nestmate follower to resources. A substantial proportion of tandem runs fail because leader and follower loose contact. Using the ant Temnothorax nylanderi as a model system, we tested the hypothesis that tandem running success is impaired if lead…
Has long-term metal exposure induced changes in life history traits and genetic diversity of the enchytraeid worm Cognettia sphagnetorum (Vejd.)?
2004
We studied whether long-term metal exposure has affected life history traits, population growth patterns and genetic diversity of the asexual enchytraeid worm Cognettia sphagnetorum (Vejd.). Enchytraeids from metal contaminated and uncontaminated forest soil were compared by growing them individually in the laboratory and by following their population development in patchily Cu contaminated microcosms. Genetic differences between the two native populations were studied using allozyme electrophoresis. Individuals from the contaminated site had slower growth rate and they produced fewer fragments of larger size when compared to individuals from the uncontaminated site. In patchily Cu contamin…
Spatial and temporal structure of the trematode component community inValvata macrostoma(Gastropoda, Prosobranchia)
2008
SUMMARYWe conducted the first comprehensive study on the spatiotemporal structure of trematode communities in the large-mouthed valve snail,Valvata macrostoma. A total of 1103 snails were examined monthly between May and October 2007 from Lake Konnevesi, Central Finland, from a shallow (1–2 m deep) and an offshore site (5–6 m deep), located ca. 50–70 m apart. Snails were infected by 10 trematode species. The species composition and prevalence were strikingly different between the sites with high species diversity in the shallow site (all 10 species; total prevalence of sporocysts/rediae 12·1%, metacercariae 55·4%) compared to the deeper site (3 species; prevalence 15·0% and 1·9%, respective…
Terrestrial carbon and intraspecific size-variation shape lake ecosystems
2007
Conceptual models of lake ecosystem structure and function have generally assumed that energy in pelagic systems is derived from in situ photosynthesis and that its use by higher trophic levels depends on the average properties of individuals in consumer populations.These views are challenged by evidence that allochthonous subsidies of organic carbon greatly influence energy mobilization and transfer and the trophic structure of pelagic food webs, and that size variation within consumer species has major ramifications for lake communitydynamics and structure. These discoveries represent conceptual shifts that have yet to be integrated into current views on lake ecosystems. Here, we assess k…