Search results for "Production"
showing 10 items of 7600 documents
Experimental assessment of the fecundity of Eucypris virens (Ostracoda, Crustacea) under natural sex ratios
2007
Summary 1. The adaptive significance of the observed variations in sex ratios in non-marine ostracods is unclear. This study quantified the fecundity of females taken from a presumed fully sexual Eucypris virens population that were experimentally combined with different proportions of males (male : female sex ratios: 1 : 1, 1 : 2, 1 : 4, 1 : 8 and 0 : 1). 2. The results yielded no indications that female fecundity is altered by short-term variations in the proportion of males, at least not within the range of sex ratios that are common in natural ostracod populations. Complete removal of males, however, did strongly reduce hatching success of dried eggs. This suggests the need for multiple…
Conflict and the Evolution of Societies
2012
The Malthusian theory of evolution disregards a pervasive fact about human societies: they expand through conflict. When this is taken account of the long-run favors not a large population at the level of subsistence, nor yet institutions that maximize welfare or per capita output, but rather institutions that maximize free resources. These free resources are the output available to society after deducting the payments necessary for subsistence and for the incentives needed to induce pro- duction, and the other claims to production such as transfer payments and resources absorbed by elites. We develop the evolutionary underpinnings of this model, and examine the implications of free resourc…
Scheduling a cellular manufacturing system with GA
2002
The flexible manufacturing cell scheduling problem is considered with a multi-objective approach, pursuing together makespan minimisation and the in process job wait minimisation. The formulation of the scheduling problem is discussed, analysing how to generate well suited sequences, like generalised permutation sequences, and the proper construction of a JIT timing of activities. An evolutionary sequencing algorithm based on both classic genetic operators and hybrid operators is then proposed. The hybrid operators have been introduced to construct highly fit initial population, to perform periodically a local search on the population and to maintain enough genetical diversity in the actual…
Allocation patterns in modes of reproduction in two facultatively sexual cryptic rotifer species
2015
Many zooplankters rely on diapausing stages to survive unsuitable conditions in time-varying habitats. In facultativesexualrotifers, reproductive effortallocatedtothe sexuallyproduced diapausingeggs isat the expenseofthe subitaneousparthenogenetic eggs, generatingatrade-offbetweencurrentand future population growth.Thetimingand the amountof sex (the sexual pattern) affect diapausing-egg production. This switch to sex is complex because the reproductivemode is separated in distinct females: asexual (female-producing), unfertilized sexual (male-producing) and fertilizedsexual (diapause-egg-producing). We studied sexual patterns and life-history variation of these females in two crypticspecies…
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…
Effects of defoliation on male and female reproductive traits of a perennial orchid, Dactylorhiza maculata
2000
1The effects of defoliation on male reproductive traits of plants have received little attention. We conducted two field experiments with Dactylorhiza maculata (L.) Soo to examine the effects of defoliation on both male and female reproductive traits. We removed 0, 50 or 100% of leaves prior to flowering. The quality of pollen was tested by transferring pollen from the differently treated plants to untreated plants of the same population. 2The non-defoliated plants did not differ from the defoliated plants in mass of pollinia. No differences were found in the weight of seed capsules or in the proportion of embryonic seeds raised by flowers receiving pollen from differently treated pollen do…
Mate recognition as a reproductive barrier in sexual and parthenogenetic Eucypris virens (Crustacea, Ostracoda)
2013
Mate selection is one of the motors of evolution and of particular importance in the case of organisms in which sexual and parthenogenetic populations coexist. Sexual populations of the ostracod species complex Eucypris virens are often mixed with parthenogenetic ones. A powerful mate selection mechanism must exist to avoid time, energy and sperm loss, for the maintenance and success of sexual reproduction in these mixed populations. There are four types of E. virens individuals: males (diploid), sexual females (diploid) and asexual females (parthenogenetic and either di- or triploid). From one parthenogenetic population and two populations with males of E. virens, we sampled early stage ju…
Minority Integration in a Western City: An Agent-Based Modelling Approach
2019
This chapter describes the design and construction of an agent-based model we refer to as the ‘Simulation of Extended Time Integration’ (SETI) model. This model was designed with the goal of obtaining a better understanding of the conditions and mechanisms leading to the structural, social, and cultural integration of minorities into large Western societies. SETI is a virtual society with structural (employment, income, education) and demographic (marriage, reproduction, life expectancy) variables typical of Westerns countries. Initialization occurs after a hypothesized immigration event in which a single minority population settles into the majority population, bracketing the first decade …
Ecological genetics of a cyclical parthenogen in temporary habitats
1995
Populations of the rotifer Brachionus plicatilis inhabiting three temporary ponds in Torreblanca Marsh (Castellon, Spain) were regularly screened for allozyme variation, sexual reproduction levels and population densities during an annual cycle. Relevant ecological parameters in the ponds were also recorded. The electrophoretic survey of the three ponds (Poza Sur, Poza Norte and Canal Central) revealed a high level of overall genetic polymorphism in four marker loci, but only 13 multilocus genotypes were found. We classified clones into three clonal groups (SS, SM, L) characterized by unique arrays of alleles in the four marker loci, and significant differences in body shape and size. Clona…
Methodology, Sources and New Evidence
2018
This chapter presents the methodology used to construct the new estimates of regional GDP in Spain, breaking down the territory into NUTS3 and NUTS2 regions (provinces and autonomous communities respectively) and dividing sectors homogeneously into five production areas: agriculture, mining, manufacturing and public utilities, construction and services. Taken as a whole in combination with data on regional population, this information provides a picture of regional inequality in per-capita income in Spain over the long term, starting from the early stages of modern economic growth. This new quantitative evidence enables to point out some of the stylized facts observed in the regional distri…