Search results for "general [Ray burst]"

PROTECTION FIRST THEN FACILITATION: A MANIPULATIVE PARASITE MODULATES THE VULNERABILITY TO PREDATION OF ITS INTERMEDIATE HOST ACCORDING TO ITS OWN DE…

2011

Many trophically transmitted parasites with complex life cycles manipulate their intermediate host behavior in ways facilitating their transmission to final host by predation. This facilitation generally results from lowering host's antipredatory defenses when the parasite is infective to the final host. However, a recent theoretical model predicts that an optimal parasitic strategy would be to protect the intermediate host from predation when noninfective, before switching to facilitation when the infective stage is reached. We tested this hypothesis in the fish acanthocephalan parasite Pomphorhynchus laevis using the amphipod Gammarus pulex as intermediate host. Gammarids parasitized by n…

Rapid Diversification of Sperm Precedence Traits and Processes Among Three Siblingdrosophilaspecies: Divergent Sperm Precedence Mechanisms

2013

Postcopulatory sexual selection is credited with driving rapid evolutionary diversification of reproductive traits and the formation of reproductive isolating barriers between species. This judgment, however, has largely been inferred rather than demonstrated due to general lack of knowledge about processes and traits underlying variation in competitive fertilization success. Here, we resolved processes determining sperm fate in twice-mated females, using transgenic Drosophila simulans and Drosophila mauritiana populations with fluorescently labeled sperm heads. Comparisons among these two species and Drosophila melanogaster revealed a shared motif in the mechanisms of sperm precedence, wit…

SEXUAL SELECTION WHEN FERTILIZATION IS NOT GUARANTEED

2005

Much of the theory of sexual selection assumes that females do not generally experience difficulties getting their eggs fertilized, yet sperm limitation is occasionally documented. How often does male limitation form a selection for female traits that improve their mating rate? The question is difficult to test, because if such traits evolve to be efficient, sperm limitation will no longer appear to be a problem to females. Here, we suggest that changes in choosiness between populations, and in particular between virgin and mated females, offer an efficient way to test this hypothesis. We model the "wallflower effect," that is, changes in female preferences due to time and mortality costs o…

Sex in space: population dynamic consequences

1999

Sex, so important in the reproduction of bigametic species, is nonetheless often ignored in explorations of the dynamics of populations. Using a growth model of dispersal-coupled populations we can keep track of fluctuations in numbers of females and males. The sexes may differ from each other in their ability to disperse and their sensitivity to population density. As a further complication, the breeding system is either monogamous or polygamous. We use the harmonic mean birth function to account for sex-ratio-dependent population growth in a Moran–Ricker population renewal process. Incorporating the spatial dimension stabilizes the dynamics of populations with monogamy as the breeding sys…

VARIATION BETWEEN POPULATIONS AND LOCAL ADAPTATION IN ACANTHOCEPHALAN-INDUCED PARASITE MANIPULATION

2010

Many trophically transmitted parasites manipulate their intermediate host phenotype, resulting in higher transmission to the final host. However, it is not known if manipulation is a fixed adaptation of the parasite or a dynamic process upon which selection still acts. In particular, local adaptation has never been tested in manipulating parasites. In this study, using experimental infections between six populations of the acanthocephalan parasite Pomphorhynchus laevis and its amphipod host Gammarus pulex, we investigated whether a manipulative parasite may be locally adapted to its host. We compared adaptation patterns for infectivity and manipulative ability. We first found a negative eff…

2018

Aposematic theory has historically predicted that predators should select for warning signals to converge on a single form, as a result of frequency-dependent learning. However, widespread variation in warning signals is observed across closely related species, populations and, most problematically for evolutionary biologists, among individuals in the same population. Recent research has yielded an increased awareness of this diversity, challenging the paradigm of signal monomorphy in aposematic animals. Here we provide a comprehensive synthesis of these disparate lines of investigation, identifying within them three broad classes of explanation for variation in aposematic warning signals: …

Effect of prefabricated thermoformable foot orthoses on plantar surface temperature after running: A gender comparison.

2020

Abstract There is a lack of evidence about the effect of different type of foot orthoses on plantar surface temperature. Moreover, that effect could be different depending on gender due to anatomical and physiological differences between men and women. The aim of the study was to analyze the effect of a prefabricated thermoformable foot orthosis on plantar surface temperature after running and taking gender differences into account. Thirty recreational runners (15 males, mean (standard deviation): 28 (7) years, 69.7 (6.5) kg, 1.74 (0.05) cm and 22.9 (1.7) kg/m2; and 15 females: 35 (7) years, 55.2 (6.9) kg, 1.63 (0.06) cm and 20.6 (1.9) kg/m2) carried out a maximum incremental test as pre-te…

Influence of infrared camera model and evaluator reproducibility in the assessment of skin temperature responses to physical exercise.

2021

Infrared thermography (IRT) has been gaining in popularity in clinical and scientific research due to the increasing availability of affordable infrared cameras. This study aims to determine the similarity of measurement performance between three models of IRT camera during assessment of skin temperature before and after physical exercise. Three models of FLIR thermographic cameras (E60bx, Flir-One Pro LT, and C2) were tested. Thermal images were taken of the foot sole, anterior leg, and anterior thigh from 12 well-trained men, before and after a 30-min run on a treadmill. Image files were blinded and processed by three evaluators to extract the mean, maximum, and standard deviation of skin…

A preliminary investigation about the observation of regional skin temperatures following cumulative training loads in triathletes during training ca…

2019

There are controversial results in the literature concerning the concept that cumulative training load could affect basal skin temperature in the days following training sessions. The objective was to measure skin temperature in triathletes during a training camp with cumulative training load. Ten male recreational triathletes involved in a training camp underwent measurements of perception of pain and fatigue (visual analogue scale), skin temperature (infrared thermography), and jump performance (counter movement jump test) before, one day, and two days after the beginning of the training camp. All measurements were performed before the breakfast. Jump height did not differ between the day…

Comparative transcriptomic analysis of the mechanisms underpinning ageing and fecundity in social insects.

2021

The exceptional longevity of social insect queens despite their lifelong high fecundity remains poorly understood in ageing biology. To gain insights into the mechanisms that might underlie ageing in social insects, we compared gene expression patterns between young and old castes (both queens and workers) across different lineages of social insects (two termite, two bee and two ant species). After global analyses, we paid particular attention to genes of the insulin/insulin-like growth factor 1 signalling (IIS)/target of rapamycin (TOR)/juvenile hormone (JH) network, which is well known to regulate lifespan and the trade-off between reproduction and somatic maintenance in solitary insects…