Search results for "Biological Evolution"
showing 10 items of 522 documents
Towards a resolution of the lek paradox
2001
Genetic benefits in the shape of 'good genes' have been invoked to explain costly female choice in the absence of direct fitness benefits. Little genetic variance in fitness traits is expected, however, because directional selection tends to drive beneficial alleles to fixation. There seems to be little potential, therefore, for female choice to result in genetic benefits, giving rise to the 'lek paradox'. Nevertheless, evidence shows that genetic variance persists despite directional selection and genetic benefits of female choice are frequently reported. A theoretical solution to the lek paradox has been proposed on the basis of two assumptions: that traits are condition-dependent, and th…
Mate choice for optimal (k)inbreeding.
2011
Mating between related individuals results in inbreeding depression, and this has been thought to select against incestuous matings. However, theory predicts that inbreeding can also be adaptive if it increases the representation of genes identical by descent in future generations. Here, I recapitulate the theory of inclusive fitness benefits of incest, and extend the existing theory by deriving the stable level of inbreeding in populations practicing mate choice for optimal inbreeding. The parsimonious assumptions of the model are that selection maximizes inclusive fitness, and that inbreeding depression is a linear function of homozygosity of offspring. The stable level of inbreeding that…
Evolutionary Hysteresis and Ratchets in the Evolution of Periodical Cicadas
2019
It has been previously hypothesized that the perfectly synchronized mass emergence of periodical cicadas (Magicicada spp.) evolved as a result of a switch from size-based to age-based emergence. In the former case, cicada nymphs emerge immediately (at the first opportunity) on reaching maturity, whereas in the latter case, nymphs wait in order to emerge at a specific age. Here we use an individual-based model to simulate the cicada life cycle and to study the evolution of periodicity. We find that if age-based emergence evolves in a constant abiotic environment, it typically results in a population that is protoperiodic, and synchronous emergence of the whole population is not achieved. How…
Vector Transmission of a Plant-Pathogenic Bacterium in the Arsenophonus Clade Sharing Ecological Traits with Facultative Insect Endosymbionts
2009
Bressan, A., Semetey, O., Arneodo, J., Lherminier, J., and BoudonPadieu, E. 2009. Vector transmission of a plant-pathogenic bacterium in the Arsenophonus clade sharing ecological traits with facultative insect endosymbionts. Phytopathology 99:1289-1296. The planthopper Pentastiridius leporinus (Hemiptera: Cixiidae) is the major vector of a nonculturable plant-pathogenic γ-3 proteobacterium associated with a disease of sugar beet called syndrome “basses richesses” (SBR). The bacterium, here called SBR bacterium, belongs to the Arsenophonous clade, which includes mostly insect-associated facultative symbionts. Assays using field-collected planthopper nymphs and adults were carried out to inve…
Sibling cooperation in earwig families provides insights into the early evolution of social life.
2014
The evolutionary transition from solitary to social life is driven by direct and indirect fitness benefits of social interactions. Understanding the conditions promoting the early evolution of social life therefore requires identification of these benefits in nonderived social systems, such as animal families where offspring are mobile and able to disperse and will survive independently. Family life is well known to provide benefits to offspring through parental care, but research on sibling interactions generally focused on fitness costs to offspring due to competitive behaviors. Here we show experimentally that sibling interactions also reflect cooperative behaviors in the form of food sh…
Magnetic resonance pharmacokinetic imaging clusterization of hepatocellular carcinomas as a means to grade tumor aggressiveness.
2012
Hepatocellular carcinoma (HCC) management takes into account clinical and radiological findings, such as tumor stage, hepatic functional status and clinical symptoms. It is necessary to evaluate the number, size and location of the lesions. However, lesion aggressiveness is not considered in this therapeutic workflow, although the biology and the growth rate of the lesions have an important impact on survival. The aim of this work was to establish if the quantitative pharmacokinetic assessment of dynamic contrast-enhanced magnetic resonance images of HCC can separate lesions with different microvascular properties and biological evolution. Forty five patients with HCC and dynamic contrast-e…
Species-specific effects of single sensillum ablation on mating position in Drosophila.
2003
0022-0949 (Print) Comparative Study Journal Article Research Support, Non-U.S. Gov't; Dipteran insects show a wide range of species-specific mating positions. Interspecific transitions from one position to another may reflect sexual or natural selection, or be pleiotropic consequences of other genetic changes. Like many cyclorrhaphan flies, Drosophila species mate with the male on the back of the female, positioned centrally. Mechanosensory sensilla on the male genitalia of three species of the melanogaster species sub-group of Drosophila have species-specific effects on mating position and on courtship success: ablation of a single pair of bristles on the genital claspers of D. melanogaste…
Late Pleistocene Human Evolution in Sicily: Comparative morphometric analysis of grotta di San Teodoro craniofacial remains.
2007
Late Pleistocene human evolution in Sicily: comparative morphometric analysis of Grotta di San Teodoro craniofacial remains. D'Amore G, Di Marco S, Tartarelli G, Bigazzi R, Sineo L. Source Laboratorio di Archeoantropologia, Soprintendenza per i Beni Archeologici della Toscana, Via dei Rossi 26/A, 50018 Scandicci, Firenze, Italy. Abstract The paleoanthropological remains from Grotta di San Teodoro near Acquedolci (province of Messina, Italy) represent the oldest and largest skeletal collection yet found documenting human settlement of Sicily. The sample, attributed to the Late Epigravettian (between 14,000 and 10,000 years B.P.), consists of seven variously complete adult individuals (San Te…
Quantifying male attractiveness
2003
Genetic models of sexual selection are concerned with a dynamic process in which female preference and male trait values coevolve. We present a rigorous method for characterizing evolutionary endpoints of this process in phenotypic terms. In our phenotypic characterization the mate-choice strategy of female population members determines how attractive females should find each male, and a population is evolutionarily stable if population members are actually behaving in this way. This provides a justification of phenotypic explanations of sexual selection and the insights into sexual selection that they provide. Furthermore, the phenotypic approach also has enormous advantages over a genetic…
Selection analysis on the rapid evolution of a secondary sexual trait
2015
Evolutionary analyses of population translocations (experimental or accidental) have been important in demonstrating speed of evolution because they subject organisms to abrupt environmental changes that create an episode of selection. However, the strength of selection in such studies is rarely measured, limiting our understanding of the evolutionary process. This contrasts with long-term, mark–recapture studies of unmanipulated populations that measure selection directly, yet rarely reveal evolutionary change. Here, we present a study of experimental evolution of male colour in Trinidadian guppies where we tracked both evolutionary change and individual-based measures of selection. Guppie…