Search results for "Biological evolution"
showing 10 items of 522 documents
The effects of reproduction on courtship, fertility and longevity within and between alternative male mating tactics of the horned beetle, Onthophagu…
2007
Life history theory provides a powerful tool to study an organism's biology within an evolutionary framework. The notion that males face a longevity cost of competing for and displaying to females lies at the core of sexual selection theory. Likewise, recent game theory models of the evolution of ejaculation strategies assume that males face a trade-off between expenditure on the ejaculate and expenditure on gaining additional matings. Males of the dung beetle Onthophagus binodis adopt alternative reproductive tactics in which major males fight for and help provision females, and minor males sneak copulations with females that are guarded by major males. Minor males are always subject to sp…
Males influence maternal effects that promote sexual selection: a quantitative genetic experiment with dung beetles Onthophagus taurus
2003
J.S.K. was funded by the Academy of Finland, L.W.S. by the Australian Research Council, J.H. by an Australian Postgraduate Award, and J.L.T. by a postdoctoral research fellowship from the University of Western Australia. Recently, doubt has been cast on studies supporting good genes sexual selection by the suggestion that observed genetic benefits for offspring may be confounded by differential maternal allocation. In traditional analyses, observed genetic sire effects on offspring phenotype may result from females allocating more resources to the offspring of attractive males. However, maternal effects such as differential allocation may represent a mechanism promoting genetic sire effects…
Cuticular hydrocarbons: their evolution and roles in Drosophila pheromonal communication
2005
0001-8244 (Print) Journal Article Review; I review the recent literature on cuticular hydrocarbons (CHs) in Drosophila. First, the major structural features of CHs are examined in a variety of species with regard to phylogeny. The genetic bases of the CH variation between and within species have been investigated with some of the genes involved characterized and manipulated. The effect of non-genetic factors as temperature, food and development is also examined with regard to CH production. Using a model involving the stimulating or the inhibiting role of CHs, it is possible to speculate on the mechanisms of CH perception and on the role(s) that these substances could play on sexual isolati…
Sexual conflict over the duration of copulation in Drosophila montana: why is longer better?
2009
Background Conflicts of interest between the sexes are increasingly recognized as an engine driving the (co-)evolution of reproductive traits. The reproductive behaviour of Drosophila montana suggests the occurrence of sexual conflict over the duration of copulation. During the last stages of copulation, females vigorously attempt to dislodge the mounting male, while males struggle to maintain genital contact and often successfully extend copulations far beyond the females' preferred duration. Results By preventing female resistance, we show that females make a substantial contribution towards shortening copulations. We staged matings under different sex ratio conditions, and provide eviden…
To quiver or to shiver: increased melanization benefits thermoregulation, but reduces warning signal efficacy in the wood tiger moth
2013
Melanin production is often considered costly, yet beneficial for thermoregulation. Studies of variation in melanization and the opposing selective forces that underlie its variability contribute greatly to understanding natural selection. We investigated whether melanization benefits are traded off with predation risk to promote observed local and geographical variation in the warning signal of adult male wood tiger moths ( Parasemia plantaginis ). Warning signal variation is predicted to reduce survival in aposematic species. However, in P. plantaginis , male hindwings are either yellow or white in Europe, and show continuous variation in melanized markings that cover 20 to 90 per cent o…
Age, pathogen exposure, but not maternal care shape offspring immunity in an insect with facultative family life.
2016
Background To optimize their resistance against pathogen infection, individuals are expected to find the right balance between investing into the immune system and other life history traits. In vertebrates, several factors were shown to critically affect the direction of this balance, such as the developmental stage of an individual, its current risk of infection and/or its access to external help such as parental care. However, the independent and/or interactive effects of these factors on immunity remain poorly studied in insects. Results Here, we manipulated maternal presence and pathogen exposure in families of the European earwig Forficula auricularia to measure whether and how the sur…
Laboratory relationships between adult lifetime reproductive success and fitness surrogates in a Drosophila littoralis population.
2011
The difficulties in measuring total fitness of individuals necessitate the use of fitness surrogates in ecological and evolutionary studies. These surrogates can be different components of fitness (e.g. survival or fecundity), or proxies more uncertainly related to fitness (e.g. body size or growth rate). Ideally, fitness would be measured over the lifetime of individuals; however, more convenient short-time measures are often used. Adult lifetime reproductive success (adult LRS) is closely related to the total fitness of individuals, but it is difficult to measure and rarely included in fitness estimation in experimental studies. We explored phenotypic correlations between female adult LRS…
Evolution of alternative male morphotypes in oxyurid nematodes: a case of convergence?
2014
Male dimorphism has been reported across different taxa and is usually expressed as the coexistence of a larger morph with exaggerated male traits and a smaller one with reduced traits. The evolution and maintenance of male dimorphism are still poorly understood for several of the species in which it has been observed. Here, we analyse male dimorphism in several species of reptile parasitic nematodes of the genus Spauligodon, in which a major male morph (exaggerated morph), which presents the traditional male morphological traits reported for this taxon, coexists with a minor morph with reduced morphological traits (i.e. reduced genital papillae) resembling more closely the males of the sis…
Drosophila female courtship and mating behaviors: sensory signals, genes, neural structures and evolution.
2010
International audience; Interest in Drosophila courtship behavior has a long-standing tradition, starting with the works by Sturtevant in 1915, and by Bastock and Manning in the 50s. The neural and genetic base of Drosophila melanogaster courtship behavior has made big strides in recent years, but the studies on males far outnumber those on females. Recent technical developments have made it possible to begin to unravel the biological substrates underlying the complexity of Drosophila female sexual behavior and its decisive effect on mating success. The present review focus more on the female side and summarizes the sensory signals that the male sends, using multiple channels, and which neu…
Facial patterns in Cercopithecoidea and Hominoidea: a geometric approach.
2006
The maxillofacial and orbital compartments of the primate skull contribute to the ontogenetic and phylogenetic variability of the viscerocranium and are of crucial evolutionary relevance. As the form of organisms changes depending on endo- and exogenous factors, metrical evaluation of specific adaptations and incorporation of the results into a biological framework could be helpful in identifying valid characters for separation of taxa (e.g. family, genus, and species) and in understanding divergence and convergence. During the last two decades a morphometric "revolution" heralded by Rohlf & Marcus (1993), Adams et al. (2004) and Oxnard (2004) brought about a synthesis of traditional quanti…