Search results for "life history"

Biological causes of cornflower regression

2012

International audience; Agroecosystems are currently experiencing high biodiversity loss. This decline results from intensive cropping systems. However, not all the anciently present weeds respond similarly. There should be specific biological traits that render some species more prone to disappear from arable fields than others. Investigating the biological causes of regression could inform about management strategies in changing agricultural farming systems. In this report we focus on cornflower (Centaurea cyanus) that is an emblem of the flora associated with traditional cereals in Europe. It is currently disappearing from Western regions. Several traits were investigated as seed longevi…

Is timing everything? : a longitudinal perspective on adult transitions, their antecedents, and psychological implications

2012

Life-history constraints and warning signal expression in an arctiid moth

2007

Summary 1 Traditionally, large pattern elements in conspicuous warning signals are assumed to be selected by predation because increasing signal strength enhances education and avoidance of predators. However, variation in the colour pattern of a warningly coloured species often exists even within a location, and many warning signals have relatively small pattern elements. This suggests that there must be opposing selection pressures that can constrain warning signal expression, resulting in variation in warning signals as well as suboptimal signals for predator education. 2 We quantified the variation in the warning signal of Parasemia plantaginis-moth larvae. With a full-sib rearing exper…

Melanin-based colour polymorphism signals aggressive personality in nest and territory defence in the tawny owl (Strix aluco)

2013

Nest and territory defence are risky and potentially dangerous behaviours. If the resolution of life history trade-offs differs between individuals, the level of defence may also vary among individuals. Because melanin-based colour traits can be associated with life history strategies, differently coloured individuals may display different nest and territory defence strategies. We investigated this issue in the colour polymorphic tawny owl (Strix aluco) for which plumage varies from dark to light reddish melanic. Accordingly, we found that (1) our presence induced a greater response (flying around) from dark-coloured than light-coloured females and (2) dark reddish males suffered lower nest…

Los jefes del primer carlismo

2018

En este artículo he intentado averiguar qué tipo de personas fueron los jefes carlistas que participaron en la primera guerra. Para ello he seleccionado a los 100 más destacados y he elaborado una serie de estadísticas con sus datos biográficos. La información la he extraído de la obra de Pirala, de otros trabajos sobre la Primera Guerra Carlista y de varias obras biográficas sobre jefes carlistas. Con esta investigación he podido saber que la mayoría de los jefes carlistas procedían de Cataluña, el País Vasco y Navarra, que eran en su mayoría militares apartados del servicio o jefes de voluntarios realistas y que tuvieron una trayectoria vital bastante variada, habiendo entre ellos idealis…

Phenolic metabolites from 5,000-year-old coprolites of Myotragus balearicus, an extinct insular bovid

2020

Abstract To date, the identification of polyphenols in the archaeological and palaeontological record has been limited. Here, we demonstrate for the first time the presence of flavonoid and phenolic metabolites from non-mineralised coprolites belonging to a non-human mammal species. Myotragus balearicus is the last species of a bovid lineage that became extinct during the Holocene in the western Mediterranean basin. In this work, we characterize the phenolic metabolites of M. balearicus coprolites for the first time. The chemical analysis of coprolites revealed the presence of flavonoids, such as flavones and flavonols. Moreover, the detection of conjugates of hydroxyphenylvaleric, hydroxyp…

Marine food web perspective to fisheries‐induced evolution

2021

Abstract Fisheries exploitation can cause genetic changes in heritable traits of targeted stocks. The direction of selective pressure forced by harvest acts typically in reverse to natural selection and selects for explicit life histories, usually for younger and smaller spawners with deprived spawning potential. While the consequences that such selection might have on the population dynamics of a single species are well emphasized, we are just beginning to perceive the variety and severity of its propagating effects within the entire marine food webs and ecosystems. Here, we highlight the potential pathways in which fisheries‐induced evolution, driven by size‐selective fishing, might reson…

Optimal rates of bisexual reproduction in cyclical parthenogens with density‐dependent growth

1999

This work explores theoretical patterns of reproduction that maximize the production of resting eggs and the long-term fitness of genotypes in cyclical parthenogens. Our focus is on density-dependent reproduction as it influences the consequences of a trade-off between producing amictic daughters – which reproduce parthenogenetically and subitaneously – and producing mictic daughters – which undergo meiosis and bisexual reproduction. Amictic females increase competitive ability and allow the population to achieve a larger size; mictic females directly contribute to population survival through harsh periods by producing resting eggs. Although morphologically indistinguishable, the two types …

Selection on life-history traits and genetic population divergence in rotifers

2009

A combination of founder effects and local adaptation – the Monopolization hypothesis – has been proposed to reconcile the strong population differentiation of zooplankton dwelling in ponds and lakes and their high dispersal abilities. The role genetic drift plays in genetic differentiation of zooplankton is well documented, but the impact of natural selection has received less attention. Here, we compare differentiation in neutral genetic markers (FST) and in quantitative traits (QST) in six natural populations of the rotifer Brachionus plicatilis to assess the importance of natural selection in explaining genetic differentiation of life-history traits. Five life-history traits were measur…

Measuring the potential for growth in populations investing in diapause

2014

AbstractThe intrinsic rate of population increase (r) is a common performance measure in many ecological and evolutionary studies. However, in life cycles with diapause investment resources are split into a short-term (current population growth) and a long-term (population survival through periods of unsuitable habitat conditions) component, which complicates the use of r as a single performance measure. Here we propose a new measure that integrates both performance components into a single parameter, the potential intrinsic growth rate, rpot. This is the rate of increase that a population/genotype would have if no investment in diapausing stages would occur. We show that rpot can be comput…