Search results for "102"

Dental microwear texture gradients in guinea pigs reveal that material properties of the diet affect chewing behaviour

2021

ABSTRACT Dental microwear texture analysis (DMTA) is widely used for diet inferences in extant and extinct vertebrates. Often, a reference tooth position is analysed in extant specimens, while isolated teeth are lumped together in fossil datasets. It is therefore important to test whether dental microwear texture (DMT) is tooth position specific and, if so, what causes the differences in wear. Here, we present results from controlled feeding experiments with 72 guinea pigs, which received either fresh or dried natural plant diets of different phytolith content (lucerne, grass, bamboo) or pelleted diets with and without mineral abrasives (frequently encountered by herbivorous mammals in natu…

Adaptive strategies of territory formation

2003

How do territorial animals gain ownership of an area? Early modelling has considered the evolution of fighting when the winner can claim the right to the resource. Recently, alternative hypotheses have been offered where repeated interactions lead to division of space through 'nagging' instead of one decisive fight. However, these models assume that animals avoid areas in which they have taken part in aggressive interactions, but do not consider whether avoidance itself is adaptive. We aim to bridge this gap between mechanistic and adaptive explanations, by presenting a game-theory model where individuals choose whether to return to an area after a fight with a specific outcome (win, loss, …

Différenciation morphologique et génétique des populations de douroucoulis (Aotus infulatus, Primates, Platyrhiniens, Cebidae) provenant des rives dr…

2007

11 pages; La morphologie crânienne de 28 spécimens de douroucoulis (genre Aotus), provenant du Bassin amazonien, a été étudiée à l'aide de méthodes de morphométrie géométrique en trois dimensions. De nouveaux résultats concernant la distinction morphologique de populations de l'espèce Aotus infulatus, réparties de part et d'autre du rio Tocantins, sont proposés. Ces résultats morphologiques concordent avec la distinction génétique de ces populations publiée par Schneider – et Sampaio –, et indiquent probablement de récents et rapides changements évolutifs au sein de cette espèce. Les résultats de cette étude ont une application taxinomique, mais pourraient également ouvrir de nouvelles pers…

Chemosensory enrichment as a simple and effective way to improve the welfare of captive lizards

2018

Mussel Farming and Its Potential in the Baltic Sea

2017

Abstract The paper covers research findings on mussel farming and the analysis of current situation in mussel farming in the Baltic Sea. The mussel farming has a development potential in the Baltic Sea region. Some developers have chosen progressive activities to achieve the aim. For example, in Sweden the development of mussel farming is suggested as one of the instruments for reducing eutrophication. Several countries in the Baltic Sea region are in the beginning phase of the mariculture development. The following research methods were used in the research: studies of scientific publications, case studies and document studies on some important factors impeding the development of mussel fa…

The Leiobunum rupestre species group: resolving the taxonomy of four widespread European taxa (Opiliones: Sclerosomatidae)

2016

Within the central European opilionid fauna the widely used species names Leiobunum rupestre Herbst, 1799 and Leiobunum tisciae Avram, 1968 pose taxonomic and distributional problems. In addition, Nelima apenninica Martens, 1969 is close to L. tisciae in terms of external and genital morphology, but is specifically distinct. While coxal denticulation is largely lacking in N. apenninica, the validity of the genus Nelima Roewer, 1910 is questioned again. In addition, Leiobunum subalpinum Komposch, 1998, a recently described novelty from the eastern Alps, is closely related to L. rupestre. The four species are combined as the morphologically defined Leiobunum rupestre species group. Except for…

Synthesis of habitat restoration impacts on young-of-the-year salmonids in boreal rivers

2019

River restoration offers the potential to enhance biological integrity, often measured as fish population changes. We used a meta-analytical approach to synthesize density responses to in-stream habitat restoration by young-of-the year (YOY) brown trout and Atlantic salmon in 28 rivers (overall 32 restoration projects) in Finland. We also examined which local and watershed-scale factors most influenced restoration success. Finally, we conducted an expert survey to obtain an independent estimate of a sufficient density enhancement for restoration to be considered successful. Despite strong context-dependency, habitat restoration had an overall positive effect on YOY salmonid density. When co…

The Bias of combining variables on fish's aggressive behavior studies.

2019

Made available in DSpace on 2019-10-06T16:27:42Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-07-01 Quantifying animal aggressive behavior by behavioral units, either displays or attacks, is a common practice in animal behavior studies. However, this practice can generate a bias in data analysis, especially when the variables have different temporal patterns. This study aims to use Bayesian Hierarchical Linear Models (B-HLMs) to analyze the feasibility of pooling the aggressive behavior variables of four cichlids species. Additionally, this paper discusses the feasibility of combining variables by examining the usage of different sample sizes and family distributions to aggressive …

Nest defence against avian brood parasites is promoted by egg-removal events in a cowbird–host system

2011

Recent studies of birds have found that the antiparasite behaviour of host species is modified by social learning. We tested whether individual or social learning modifies the nest defence of yellow warblers, Setophaga petechia, against the parasitic brown-headed cowbird, Molothrus ater. Using field experiments, we exposed warblers to simulated events of nest parasitism and predation, or allowed them to observe conspecifics mobbing a cowbird. Intensity of nest defence by yellow warblers was greater after simulated threats at their nest than after they had observed mobbing of cowbirds by conspecifics. Warblers defended their nests more aggressively when they perceived a cowbird as an egg pre…

2021

Hosts of brood parasitic cuckoos often employ mobbing attacks to defend their nests and, when mobbing is costly, hosts are predicted to adjust their mobbing to match parasitism risk. While evidence exists for fine-tuned plasticity, it remains unclear why mobbing does not track larger seasonal changes in parasitism risk. Here we test a possible explanation from parental investment theory: parents should defend their current brood more intensively as the opportunity to replace it declines (re-nesting potential), and therefore “counteract” any apparent seasonal decline to match parasitism risk. We take advantage of mobbing experiments conducted at two sites where reed warblers (Acrocephalus sc…