Search results for "Selection"

Sexual selection and the chemical signal design of lacertid lizards

2018

Animal signals can differ considerably in complexity and composition, even among closely related species. Work on vocal and visual signals has revealed how sexual selection can elaborate signals relevant in mate choice or rival assessment, but few studies have investigated this process in chemical signals. In this study, we correlated chemical signalling diversity and richness with degree of sexual dimorphism in a data set of 60 species of the lizard family Lacertidae. The femoral glands of male lacertid lizards exude waxy secretions, of which the lipophilic fraction is known to function in chemical communication. We determined the composition of the gland secretions using gas chromatograph…

Ageing via perception costs of reproduction magnifies sexual selection.

2018

Understanding what factors modulate sexual selection intensity is crucial to a wide variety of evolutionary processes. Recent studies show that perception of sex pheromones can severely impact male mortality when it is not followed by mating (perception costs of reproduction). Here, we examine the idea that this may magnify sexual selection by further decreasing the fitness of males with inherently low mating success, hence increasing the opportunity for sexual selection. We use mathematical modelling to show that even modest mortality perception costs can significantly increase variability in male reproductive success under a wide range of demographic conditions. We then conduct a series …

Biased predation could promote convergence yet maintain diversity within Müllerian mimicry rings of Oreina leaf beetles.

2019

Mullerian mimicry is a classic example of adaptation, yet Muller's original theory does not account for the diversity often observed in mimicry rings. Here, we aimed to assess how well classical Mullerian mimicry can account for the colour polymorphism found in chemically defended Oreina leaf beetles by using field data and laboratory assays of predator behaviour. We also evaluated the hypothesis that thermoregulation can explain diversity between Oreina mimicry rings. We found that frequencies of each colour morph were positively correlated among species, a critical prediction of Mullerian mimicry. Predators learned to associate colour with chemical defences. Learned avoidance of the green…

Direct and correlated responses to bi-directional selection on pre-adult development time in Drosophila montana.

2019

Selection experiments offer an efficient way to study the evolvability of traits that play an important role in insects’ reproduction and/or survival and to trace correlations and trade-offs between them. We have exercised bi-directional selection on Drosophila montana flies’ pre-adult development time under constant light and temperature conditions for 10 generations and traced the indirect effects of this selection on females’ diapause induction under different day lengths, as well as on the body weight and cold tolerance of both sexes. Overall, selection was successful towards slow, but not towards fast development. However, all fast selection line replicates showed at the end of selecti…

Intensity of male-male competition predicts morph diversity in a color polymorphic lizard.

2017

Sexual selection is one of the main processes involved in the emergence and maintenance of heritable colour polymorphisms in a variety of taxa. Here we test whether the intensity of sexual selection, estimated from population sex ratio, predicts morph diversity in Podarcis muralis, a colour polymorphic lizard with discrete white, yellow, orange, white-orange, and yellow-orange male and female phenotypes (i.e. morphs). In a sample of 116 Pyrenean populations and 5421 lizards, sex ratios (m/f) vary from 0.29 to 2.5, with the number of morphs for each sex ranging from 2 to 5. Male-biased sex ratios are associated with increased morph diversity as measured with Shannon's diversity index. The ma…

Effects of the temporal scale of observation on the analysis of aquatic invertebrate metacommunities

2020

The development of metacommunity theory has boosted the implementation of numerous empirical tests with field data, mostly focused on the role of spatial and environmental gradients on metacommunity organization. These studies showed an important dependence of the results on the observational scale considered, i.e., spatial grain, sampling spacing, and extent. However, few works deal with time per se as a component explaining metacommunity structure, even when data from periodic sampling are available. We suggest adding time explicitly to metacommunity analysis, but taking into account that the temporal scale of observation could affect the estimation of the relative influence of environmen…

Genomic processes underlying rapid adaptation of a natural Chironomus riparius population to unintendedly applied experimental selection pressures

2020

Evolve and Resquence (E&R) studies are a useful tool to study genomic processes during rapid adaptation, e.g., in the framework of adaptive responses to global climate change. We applied different thermal regimes to a natural Chironomus riparius (Diptera) population in an E&R framework to infer its evolutionary potential for rapid thermal adaptation. We exposed two replicates to three temperatures each (14°C, 20°C and 26°C) for more than two years, the experiment thus lasting 22, 44 or 65 generations, respectively. The two higher temperatures presented a priori moderate, respectively strong selection pressures. Life-cycle fitness tests revealed no appreciable adaptation to thermal regimes b…

Bacillus thuringiensis Vip3Aa Toxin Resistance in Heliothis virescens (Lepidoptera: Noctuidae)

2017

ABSTRACT Laboratory selection with Vip3Aa of a field-derived population of Heliothis virescens produced >2,040-fold resistance in 12 generations of selection. The Vip3Aa-selected (Vip-Sel)-resistant population showed little cross-resistance to Cry1Ab and no cross-resistance to Cry1Ac. Resistance was unstable after 15 generations without exposure to the toxin. F 1 reciprocal crosses between Vip3Aa-unselected (Vip-Unsel) and Vip-Sel insects indicated a strong paternal influence on the inheritance of resistance. Resistance ranged from almost completely recessive (mean degree of dominance [ h ] = 0.04 if the resistant parent was female) to incompletely dominant (mean h = 0.53 if the resistan…

2018

Chemically defended animals often display conspicuous colour patterns that predators learn to associate with their unprofitability and subsequently avoid. Such animals (i.e. aposematic), deter predators by stimulating their visual and chemical sensory channels. Hence, aposematism is considered to be ‘multimodal’. The evolution of warning signals (and to a lesser degree their accompanying chemical defences) is fundamentally linked to natural selection by predators. Lately, however, increasing evidence also points to a role of sexual selection shaping warning signal evolution. One of the species in which this has been shown is the wood tiger moth, Arctia plantaginis, which we here put forward…

Condition‐dependent mortality exacerbates male (but not female) reproductive senescence and the potential for sexual conflict

2020

Disentangling the relationship between age and reproduction is central to understand life-history evolution, and recent evidence shows that considering condition-dependent mortality is a crucial piece of this puzzle. For example, nonrandom mortality of 'low-condition' individuals can lead to an increase in average lifespan. However, selective disappearance of such low-condition individuals may also affect reproductive senescence at the population level due to trade-offs between physiological functions related to survival/lifespan and the maintenance of reproductive functions. Here, we address the idea that condition-dependent extrinsic mortality (i.e. simulated predation) may increase the a…