Search results for " Reproduction"

The evolution of sex roles in mate searching

2016

Searching for mates is a critical stage in the life cycle of most internally, and many externally, fertilizing species. Males usually invest more in this costly activity than females, but the reasons for this are poorly understood. Previous models have shown that female-biased parental investment, including anisogamy, does not by itself select for male-biased mate searching, so it requires additional explanations. Here, we correct and expand upon earlier models, and present two novel hypotheses that might explain the evolution of male-biased mate searching. The "carry-over hypothesis" states that females benefit less from searching if the associated costs affect other stages of the life cyc…

Social capital and the networked public sphere: Implications for political social media sites

2012

Submitted version of a paper from the 45th Hawaii International Conference on System Science (HICSS), 2012. Published version available from IEEE: http://dx.doi.org/10.1109/hicss.2012.535 This paper presents a theoretical lens for research on social media use in eParticipation, along with an example case study. The idea of the public sphere and how it can be applied to eParticipation research is presented. The public sphere is discussed in relation to Castell's notion of the network society as the "networked public sphere", and social capital is introduced as a possible explanation for why some people choose to participate while others refrain from doing so. An example case is presented and…

Evolutionary population dynamics

2005

The interface between the evolution of life history traits and population dynamics in temporally and spatially variable environments is the topic of this chapter. Thus, the frame for the life history processes is set by spatial and temporal fluctuations in population density. Here, we will focus primarily on modes of reproduction and we are especially interested in whether alternative reproductive strategies can co-exist in a population. We show that spatially structured populations may allow co-existence of various life history strategies that do not easily co-exist in a nonstructured environment. Also, intrinsic and external temporal fluctuations in the environment tend to enhance polymor…

Corporate Reputation and the Theory of Social Capital

2013

Color constancy in dermatoscopy with smartphone

2017

The recent spread of cheap dermatoscopes for smartphones can empower patients to acquire images of skin lesions on their own and send them to dermatologists. Since images are acquired by different smartphone cameras under unique illumination conditions, the variability in colors is expected. Therefore, the mobile dermatoscopic systems should be calibrated in order to ensure the color constancy in skin images. In this study, we have tested a dermatoscope DermLite DL1 basic, attached to Samsung Galaxy S4 smartphone. Under the controlled conditions, jpeg images of standard color patches were acquired and a model between an unknown device-dependent RGB and a device independent Lab color space h…

Emotions et personnalité : au cœur des décisions chez un poisson monogame

2018

During their lives animals constantly need to make decisions that influence their survival and their reproductive success. The objective of this thesis was to evaluate the role of two variability sources in decision-making — personality and emotional states — in a sexual context in a monogamous fish, the convict cichlid. Our work about personality highlights its importance on pair compatibility and reproductive success. We also observe that reactive individuals adjusted their behaviour to their partner and thus increased their reproductive fitness. This result supports the hypothesis that reactive individuals are more flexible and thus compensate for their weak competitiveness.Personality t…

Modalités fonctionnelles et évolutives des parasitoses développées par les crabes Pinnotheridae aux dépens des échinides fouisseurs

2010

Ce travail s’est intéressé aux liens existant entre la stratégie d’exploitation développée par un crustacé ectoparasite et son comportement reproductif. Le crabe Pinnotheridae Dissodactylusprimitivus exploite deux espèces Spatangidae vivant dans la Mer des Caraïbes, Meomaventricosa et Plagiobrissus grandis. Des approches comportementales, démographiques etgénétiques ont été adoptées afin de mettre en lumière le fonctionnement et la biologie de cettesymbiose. Par son comportement alimentaire, le crabe occasionne des lésions tégumentairessur ses hôtes. Celles-ci affectent la fitness de M. ventricosa, au travers de son développementgonadique. Dissodactylus primitivus exploite ses deux espèces …

Pollen-pollen interactions in Betula pendula in vitro

1998

Direct pollen interactions, as well as interactions mediated by a recipient, can have a remarkable influence on pollen fertilization ability. Under conditions of pollen competition it could be advantageous if pollen grains interfered with the germination of other pollen. The aim of this study was to find out if there are direct negative or positive pollen–pollen interactions between pollen grains from genetically slightly different donors. The in vitro germinability of the pollen from several Betula pendula Roth clones was investigated. The pollen interactions between the clones were examined pairwise by using equal pollen mixtures. In three of the eight cases the germination percentage of …

Early bearing and vegetative growth of 153 Sicilian olive accessions

2018

In 2014, an olive germplasm collection was established in south-western Sicily, Italy. The collection included 153 Sicilian accessions and 3 international varieties (reference), each with 7 trees, spaced at 5×2 m and trained to hedgerow system. The aim of the trial was to study early growth and yield responses of the accessions to super-high planting density (SHD). Trunk cross sectional area, tree height, pruning weights, shoot positioning, blooming and fruit yield (kg tree-1) were measured in 2015 and 2016. Based on trunk growth and amount of prunings, the 153 accessions were separated into four categories of vigor as it follows: very high vigor (6 accessions), high vigor (13), medium vigo…

Halophila stipulacea descriptors in the native area (Red Sea): A baseline for future comparisons with native and non-native populations

2018

Abstract Halophila stipulacea is a small tropical seagrass species native to the Red Sea. Due to its invasive character, there is growing interest in understanding its ability to thrive in a broad range of ecological niches. We studied temporal (February 2014 and July 2014), depth (5, 9, 18 m) and spatial (NB and SB) related dynamics of H. stipulacea meadows in the northern Gulf of Aqaba. We evaluated changes in density, morphometry, biomass, and biochemical parameters alongside the reproductive effort. In both sites, maximal growth and vegetative performance occurred in the summer with a marked increase of 35% in shoot density and 18% in biomass; PAR reduction with season and depth induced…