1,081 research outputs found
Lactation patterns of pinnipeds are not explained by optimization of maternal energy delivery rates
No full textTrillmich F, Weissing FJ. Lactation patterns of pinnipeds are not explained by optimization of maternal energy delivery rates. BEHAVIORAL ECOLOGY AND SOCIOBIOLOGY. 2006;60(2):137-149.Within pinnipeds, phocids and otariids show differing maternal care. strategies. Phocids rear young out of body stores in a yearly cycle with a single stay ashore when the mother fasts while lactating, whereas otariids provision their young by repeated foraging trips to sea alternating with brief stays ashore where they suckle their young. In a previous optimality model, these differences have been interpreted as adaptations based on differing energy requirements of large (phocid) and smaller (otariid) species, and the time budget of the large elephant and the much smaller Antarctic fur seal were correctly predicted. Our refined model-extended to pinniped species of all sizes-predicts lactation strategies to shift from attendance cycles to 1-year cycles with increasing body mass and provides an explanation for the finding that phocid pups are weaned at lower relative mass than otariid pups. However, other predictions do not correspond to empirical findings. In particular, the model does not explain the behavior of large otariids and small phocids. Thus, maternal metabolic requirements alone appear insufficient to explain observed lactation patterns. In the light of our results, we discuss more generally the scope and limitations of optimality models when applied in a comparative framework to a group of related species
Selection and Segregation Distortion in a Sex-Differentiated Population
No full textthis paper, we will focus on the interaction of selection and segregation distortion, which is harder to analyze and less well understood (e.g., Taylor and Jonker, 1978; Weissing, 1991; Hofbauer and Sigmund, 1998). In this case, w ij should be interpreted as the fitness of an individual of genotype A i A j viewed from the perspective of allele A i . Hence, our model explicitly takes the point of view of the allele instead of that of the genotyp
Data: Effects of sex and sex-related facial traits on trust and trustworthiness: An experimental sudy
No full textThese datasets support the findings of the article "Effects of sex and sex-related facial traits on trust and trustworthiness: An experimental study" by Rostovtseva VV, Butovskaya ML, Mezentseva AA, Weissing FJ</p
Competition for nutrients and light among phytoplankton species in a mixed water column: Theoretical studies
No full textA brief overview is given of modelling studies that aim to analyse the effects of nutrient and light limitations on the development of phytoplankton communities and lead to a qualitative understanding of the competitive interactions involved
Oscillations and chaos generated by competition for interactively essential resources
No full textRecent theory shows that: (i) competition between multiple species for multiple resources may generate oscillations and chaotic fluctuations in species abundances; and (ii) these non-equilibrium dynamics may favor a high biodiversity. These findings were based on Liebig's Law of the Minimum, which assumes that each species is limited by only one resource at a time. In reality, however, resources can have interactive effects on growth. Here, we investigate whether competition for interactively essential resources may generate oscillations and chaos as well. Our results show that competition for interactively essential resources may, indeed, exhibit dynamics of similar complexity. This illustrates the wide potential for non-equilibrium dynamics generated by multispecies competition, and suggests that competitive chaos may occur on a wide variety of different resource types
Fundamental unpredictability in multispecies competition
Get PDFOne of the central goals of ecology is to predict the distribution and abundance of organisms. Here, we show that, in ecosystems of high biodiversity, the outcome of multispecies competition can be fundamentally unpredictable. We consider a competition model widely applied in phytoplankton ecology and plant ecology in which multiple species compete for three resources. We show that this competition model may have several alternative outcomes, that the dynamics leading to these alternative outcomes may exhibit transient chaos, and that the basins of attraction of these alternative outcomes may have an intermingled fractal geometry. As a consequence of this fractal geometry, it is impossible to predict the winners of multispecies competition in advance
Irrigation institutions and the games irrigators play: Rule enforcement on government- and farmer-managed systems
No full textBiodiversity of plankton by species oscillations and chaos
No full textBiodiversity has both fascinated and puzzled biologists(1). In aquatic ecosystems, the biodiversity puzzle is particularly troublesome, and known as the 'paradox of the plankton'(2). Competition theory predicts that, at equilibrium, the number of coexisting species cannot exceed the number of limiting resources(3-6). For phytoplankton, only a few resources are potentially limiting: nitrogen, phosphorus, silicon, iron, light, inorganic carbon, and sometimes a few trace metals or vitamins. However, in natural waters dozens of phytoplankton species coexist(2). Here we offer a solution to the plankton paradox. First, we show that resource competition models(6-10) can generate oscillations and chaos when species compete for three or more resources. Second we show that these oscillations and chaotic fluctuations in species abundances allow the coexistence of many species on a handful of resources. This model of planktonic biodiversity may be broadly applicable to the biodiversity of many ecosystems. [KEYWORDS: Limited growth; competition; phytoplankton; communities limitation; hypothesis]
Reduced costs of mixed-species pairings in flycatchers: by-product or female strategy?
Get PDFHeterospecific matings are generally assumed to be unconditionally disadvantageous due to reduced viability or fertility of hybrid offspring. For female collared flycatchers (Ficedula albicollis) mated to male pied flycatchers (Ficedula hypoleuca), the cost of heterospecific pair formation is reduced due to high levels of conspecific extra-pair paternity and a male-biased offspring sex ratio. In order to investigate whether these cost-reducing mechanisms are the result of female mating strategies, rather than being a by-productof species incompatibilities, we manipulated the plumage of male collared flycatchers before pair formation to make them resemble male pied flycatchers. Since species incompatibilities are absent in this design, any systematic effect of manipulation on sec ratio or paternity would indicate a role of female mating strategy. Paternity was determined by means of a likelihood approach that controls the errors made in assigning a chick to be 'within-pair' or 'extra-pair'. Neither the sex ratio nor the male share of paternity was affected by the manipulation in a systematic manner. We therefore conclude that our experimental data provide no support for the suggestion that female behavioural strategies are markedly adjusted in response to formation of mixed-species pairs
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