Inconsistency between different measures of sexual selection.

Measuring the intensity of sexual selection is of fundamental importance to the study of sexual dimorphism, population dynamics, and speciation. Several indices, pools of individuals, and fitness proxies are used in the literature, yet their relative performances are strongly debated. Using 12 independent common lizard populations, we manipulated the adult sex ratio, a potentially important determinant of the intensity of sexual selection at a particular time and place. We investigated differences in the intensity of sexual selection, as estimated using three standard indices of sexual selection-the standardized selection gradient (β'), the opportunity of selection (I), and the Bateman gradient (βss)--calculated for different pools of individuals and different fitness proxies. We show that results based on estimates of I were the opposite of those derived from the other indices, whereas results based on estimates of β' were consistent with predictions derived from knowledge about the species' mating system. In addition, our estimates of the strength and direction of sexual selection depended on both the fitness proxy used and the pool of individuals included in the analysis. These observations demonstrate inconsistencies in distinct measures of sexual selection and underscore the need for caution when comparing studies and species

Invasion Fitness and Adaptive Dynamics in Spatial Population Models

Disentangling proximate and ultimate factors of dispersal and assessing their relative effects requires an appropriate measure of fitness. Yet there have been few theoretical attempts to coherently define fitness from demographic "first principles", when space-related traits like dispersal are adaptive. In this chapter, we present the framework of adaptive dynamics and argue that "invasion fitness" is a robust concept accounting for ecological processes that operate at the individual level. The derivation of invasion fitness for spatial ecological scenarios is presented. Spatial invasion fitness involves the effect of neighbors on a focal individual, mediated by coefficients analogous to relatedness coefficients of population genetics. Spatial invasion fitness can be used to investigate the joint evolution of dispersal and altruism - two traits that both have a direct influence on, and are strongly responsive to, the spatial distribution of individuals. Our deterministic predictions of dispersal and altruism evolution based on spatial invasion fitness are in good agreement with stochastic individual-based simulations of the mutation-selection process acting on these traits

Lifetime and intergenerational fitness consequences of harmful male interactions for female lizards.

Male mating behaviors harmful to females have been described in a wide range of species. However, the direct and indirect fitness consequences of harmful male behaviors have been rarely quantified for females and their offspring, especially for long-lived organisms under natural conditions. Here, lifetime and intergenerational consequences of harmful male interactions were investigated in female common lizards (Lacerta vivipara) using field experiments. We exposed females to male harm by changing the population sex ratio from a normal female-biased to an experimental male-biased sex ratio during the first experimental year. Thereafter, females and their first generation of offspring were monitored during two additional years in a common garden with a female-biased sex ratio. We found strong immediate fitness costs and lower lifetime reproductive success in females subjected to increased male exposure. The immediate fitness costs were partly mitigated by direct compensatory responses after exposure to male excess, but not by indirect benefits through offspring growth, offspring survival, or mating success of offspring. These results support recent empirical findings showing that the direct costs of mating are not outweighed by indirect benefits

Determinants of male fitness: disentangling intra- and inter-sexual selection.

Both intra- and inter-sexual selection may crucially determine a male's fitness. Their interplay, which has rarely been experimentally investigated, determines a male's optimal reproductive strategy and thus is of fundamental importance to the understanding of a male's behaviour. Here we investigated the relative importance of intra- and inter-sexual selection for male fitness in the common lizard. We investigated which male traits predict a male's access to reproduction allowing for both selective pressures and comparing it with a staged mating experiment excluding all types of intra-sexual selection. We found that qualitatively better males were more likely to reproduce and that sexual selection was two times stronger when allowing for both selective pressures, suggesting that inter- and intra-sexual selection determines male fitness and confirming the existence of multi-factorial sexual selection. Consequently, to optimize fitness, males should trade their investment between the traits, which are important for inter- and intra-sexual selection

The Adaptive Dynamics of Altruism in Spatially Heterogeneous Populations

We study the spatial adaptive dynamics of a continuous trait that measures individual investment in altruism. Our study is based on an ecological model of a spatially heterogeneous population from which we derive an appropriate measure of fitness. The analysis of this fitness measure uncovers three different selective processes controlling the evolution of altruism: the direct physiological cost, the indirect genetic benefits of cooperative interactions, and the indirect genetic costs of competition for space. In contrast with earliest suggestions, we find that the cost of competing for space with relatives exerts a negligible selective pressure against altruism. Our study yields a classification of adaptive patterns of altruism according to how the costs of altruism vary with an individuals investment in altruism (we distinguish between decelerating, linear, and accelerating dependence). The invasion of altruism occurs readily in species with accelerating costs, but large mutations are critical for altruism to evolve in selfish species with decelerating costs. Strict selfishness is maintained by natural selection only under very restricted conditions. In species with rapidly accelerating costs, adaptation leads to an evolutionarily stable rate of investment in altruism that decreases smoothly with the level of mobility. A rather different adaptive pattern emerges in species with slowly accelerating costs: high altruism evolves at low mobility, whereas a quasi-selfish state is promoted in more mobile species. The high adaptive level of altruism can be predicted solely from habitat connectedness and physiological parameters that characterize the pattern of cost. We also show that environmental changes that cause increased mobility in those highly altruistic species can beget selection-driven self-extinction, which may contribute to the rarity of social species

Jacques Henri Lartigue dans l’air du temps (1966-1967)

Les années soixante correspondent au moment où s’entame la canonisation véritable de la photographie de Jacques Henri Lartigue. Deux étapes majeures jalonnent l’histoire de cette lente reconnaissance : 1963, avec la première exposition monographique au Musée d’art moderne de New York, qui montre quelques images de la Belle-Époque, et 1970, avec la publication de la monographie Diary of a Century, consacrée pour la première fois à l’ensemble de son œuvre (près de soixante ans) et éditée par le célèbre photographe Richard Avedon. Les recherches récentes sur l’historiographie de la photographie de Lartigue ont montré que c’est l’exposition au MoMA qui déclenche le début de cette célébrité, notamment par son commissaire, John Szarkowski. Celui-ci aurait « inventé » Lartigue en tant qu’artiste. Mais c’est Avedon qui, sept ans plus tard, va définitivement promouvoir Lartigue au rang des grands photographes du XXe siècle avec Diary of a Century.It was in the 1960s that the canonization of the photography of Jacques Henri Lartigue truly began. The history of this gradual recognition is marked by two major milestones—the first in 1963, with the first solo exhibition at New York’s Museum of Modern Art, which displayed a number of images of the Belle Époque, and the second in 1970, with the publication of the monograph Diary of a Century, which was devoted for the first time to the entirety of his oeuvre (almost sixty years) and edited by the famous photographer Richard Avedon. Recent research on the historiography of Lartigue’s photography has shown that it was the MoMA exhibition which sparked the beginning of his celebrity, thanks especially to its curator, John Szarkowski, who is seen as having “invented” Lartigue as an artist. But it was Avedon who, seven years later, would definitively elevate Lartigue to the company of the great photographers of the twentieth century with Diary of a Century

In the spirit of the age

It was in the 1960s that the canonization of the photography of Jacques Henri Lartigue truly began. The history of this gradual recognition is marked by two major milestones — the first in 1963, with the first solo exhibition at New York’s Museum of Modern Art, which displayed a number of images of the Belle Époque, and the second in 1970, with the publication of the monograph Diary of a Century, which was devoted for the first time to the entirety of his oeuvre (almost sixty years) and edited by the famous photographer Richard Avedon. Recent research on the historiography of Lartigue’s photography has shown that it was the MoMA exhibition which sparked the beginning of his celebrity, thanks especially to its curator, John Szarkowski, who is seen as having “invented” Lartigue as an artist. But it was Avedon who, seven years later, would definitively elevate Lartigue to the company of the great photographers of the twentieth century with Diary of a Century

De la gestion de collection à l’analyse historique

L’auteur tient à remercier Jean-Luc Uro et André Gunthert pour leurs précieux conseils. Depuis 2003, un long travail de recherche sur le fonds Lartigue a été effectué au sein de la Fondation Lartigue en collaboration avec l’association des Amis de Jacques-Henri Lartigue. La Fondation Lartigue, créée en 2000 suite à un legs de la dernière femme du photographe, Florette Lartigue, à la Fondation de France, s’est jointe à l’association Lartigue en vue de tisser des liens entre les deux patrimoine..