bluuebunny/crossref_metadata_2025_split huggingface dataset:
The diversity of sexual cycles
Authors: Beukeboom Leo W. , Perrin Nicolas 
Published: August 2014

AbstractThe sexual cycles of eukaryotes vary immensely in terms of the relative importance of the haploid and diploid phases, the differentiation between gametes, and the timing and mode of sex determination. The chapter discusses the evolutionary advantages of haploid and diploid phases, the conditions for the maintenance of haplo-diplontic cycles, and the role of disruptive selection in the evolution from isogamy to anisogamy and oogamy. The chapter proposes a typology for sexual cycles based on the relative importance of haploid and diploid phase, whether sex is determined at the haploid or diploid stage, and whether the initial trigger is genetic or epigenetic. The chapter develops the concepts of heterothallism versus homothallism, haplo- versus diplo-genotypic sex determination, dioicy versus dioecy, monoicy versus monoecy, self-incompatibility systems and secondary mating types. The chapter considers the diversity of epigenetic sex-determination systems (mating-type switching, simultaneous and sequential hermaphroditism, as well as environmental, social, maternal, or parasite control of sex determination) and discusses the ultimate and proximate causes favouring their evolution, as well as their likely role in transitions from haplo- to diplo-genotypic sex determination.The electronic addendum of this chapter (Section 2.2) describes in more detail the diversity and phylogenetic distribution of sex-determination types among extant eukaryotes.
Molecular mechanisms of sex determination
Authors: Beukeboom Leo W. , Perrin Nicolas 
Published: August 2014

AbstractThis chapter first describes the overall structure of sex-determination cascades and the function of the main upstream and downstream actors (Section 3.1). Given the fundamental bipotentiality of genomes, the mechanisms of sex determination must insure proper development towards one or the other sex, and not towards intermediate phenotypes of reduced fertility. This is achieved via antagonisms that inhibit alternative pathways, and feedback auto-regulatory loops, acting as memory devices that maintain sexual identity throughout life. Transitions in sex-determination pathways may occur at any step along the cascade, through neo- or sub-functionalization following gene duplication, changes in the hierarchical position or timing of gene expression, alterations of gene function, or changes in transcriptional and translational regulation of genes. Section 3.2 delineates the structure and functioning of MAT loci, and describes specific pathways of haploid mating-type determination in a few model systems, as well as the molecular mechanisms of mating-type switching and homothallism. Section 3.3 focuses on diploid sex determination in two contrasted systems. In angiosperms, where floral meristems are organized by MADS-box transcription factors, different genders evolve via the selective abortion of male or female organs, as exemplified in a few model systems. In contrast, genders in animals evolve via the development of undifferentiated gonads into either testes or ovaries. The crucial roles of DM-domain genes in all animals, Sox genes in vertebrates, and transformer genes in insects, are developed. Finally, Section 3.4 outlines the molecular mechanisms of self-incompatibility and induction types in some diplontic or sub-diplontic lineages.
The quantitative genetics of sex determination
Authors: Beukeboom Leo W. , Perrin Nicolas 
Published: August 2014

AbstractThis chapter approaches sex determination from a quantitative genetics perspective. Although inheritance of sexes is often Mendelian, sex is better described as a threshold trait, underlain by a liability factor that may have both genetic and environmental variance. Accordingly, sex genotypes are best described as reaction norms in the multi-dimensional space generated by environmental and liability factors. Genetic variance may stem from one multi-allelic locus or multiple loci. Environmental variance may stem from a diversity of social effects (e.g. density) or external conditions, of which temperature plays a prominent role. Mixed systems, with a mixture of genotypic and environmental effects on sex determination, seem widespread, running against the traditional dichotomous view that opposes GSD to ESD. Large heritability values for the pivotal temperature have been found in ‘ESD’ species, and many studies have revealed significant genotype × environment interactions for sex ratios. Selection experiments have triggered quick sex-ratio responses to selection, even in the presence of specialised sex chromosomes. Although several case studies have uncovered examples of local adaptation, the adaptive significance of genetic and environmental control over sex determination requires further study.
Evolutionary correlates of sex-determination systems
Authors: Beukeboom Leo W. , Perrin Nicolas 
Published: August 2014

AbstractSex-determination systems have profound consequences on the biology of organisms, affecting many aspects of their life histories. Certain sex-determination systems may affect the evolution of polyploidy and parthenogenesis. Sex allocation, the relative investment of resources to the male versus female function, bears direct link with sex determination; sex chromosomes play an important role in this context because they can constrain adaptive sex allocation, harbour meiotic drive elements, or protect against the invasion of cytoplasmic sex-ratio distorters. Sex chromosomes and patterns of heterogamety may also affect sexual selection: there is extensive theory about the evolution of sex linkage of sexually dimorphic traits, including sexually antagonistic genes, but more empirical evidence is required. Finally, sex-determination systems can interfere with reproductive isolation and speciation processes. Sex chromosomes largely contribute to the several ‘rules of speciation’ including Haldane’s rule (higher sensitivity of the heterogametic sex to hybridization), Darwin’s corollary (asymmetric hybrid sensitivity), and large X-effects (disproportionate effect of X chromosomes on hybrid sterility or unviability). These reciprocal interactions between sex-determination systems and processes of sexual selection and speciation are illustrated with specific examples.
The quantitative genetics of senescence in wild animals
Authors: Charmantier Anne , Brommer Jon E. , Nussey Daniel H. 
Published: August 2014

Abstract
There is now overwhelming empirical evidence for age-related declines in fitness-related traits, i.e. senescence, during adulthood in wild vertebrate populations, presumably underpinned by physiological deterioration. Longitudinal field studies are also demonstrating that the rates of these observed declines vary among individuals and among traits. From an evolutionary perspective, the challenge remains to determine the contribution of genetic sources to this variation and the genetic correlations among traits underpinning fitness at different ages in natural systems. Although laboratory studies are revealing an ever-increasing amount about potential genetic and physiological pathways regulating lifespan and ageing in model systems, quantitative genetic studies in the wild can provide unique insights into how selection has shaped and maintained variation in ageing trajectories and senescence under complex, natural conditions. This chapter briefly discusses the classical evolutionary theories of ageing, emphasising the importance of estimating age-dependent patterns of genetic (co)variance (genotype-by-age interactions; G × A), rather than attempting to disentangle non-mutually exclusive putative mechanisms such as mutation accumulation and antagonistic pleiotropy. It provides an overview of approaches for quantifying G × A, emphasising the importance of function-valued trait models, such as the random regression animal model, and presents a critical review of the limited number of studies that have implemented these approaches in the context of wild populations. Finally, this chapter identifies a number of statistical issues/challenges that are likely to hold back much needed developments in this field and provides recommendations of ways to overcome these challenges as well as for avenues for future work.
The effects of others’ genes: maternal and other indirect genetic effects
Authors: McAdam Andrew G. , Garant Dany , Wilson Alastair J. 
Published: August 2014

AbstractAn individual’s phenotype may frequently be affected by the phenotypes (and hence genotypes) of other individuals with whom it interacts. Phenotypic effects that are caused by the genotype of another individual are referred to as indirect genetic effects, and these can have large and sometimes counterintuitive effects on evolutionary dynamics. Despite their potential importance, studies of indirect genetic effects in the wild are still rare. One class of indirect effect that has been investigated more commonly in natural populations is the effects of mothers on the phenotypes of their offspring. Maternal effects are defined as the contribution that a mother makes to the phenotypes of her offspring beyond the direct inheritance of genes from mother to offspring. Maternal effects have been widely studied phenotypically, and genetic variation in many important maternal traits has been quantified in the wild but rarely in the context of the indirect effects of this genetic variation on offspring traits. As a result, the importance of maternal genetic effects for evolutionary dynamics remains largely unexplored. This chapter provides conceptual background to the importance of maternal effects for evolution, and an overview of the various methods that can be employed to quantify maternal effects in the wild. Finally, this chapter provides some examples of important emerging questions in the field that could most rapidly advance our understanding of the importance of indirect genetic effects for evolutionary dynamics in the wild.
Case study: quantitative genetics and sexual selection of weaponry in a wild ungulate
Authors: Kruuk Loeske E. B. , Clutton-Brock Tim , Pemberton Josephine M. 
Published: August 2014

Abstract
This case study illustrates three key themes in current evolutionary quantitative genetics: the role of genetic associations in the evolutionary dynamics of selection, the insights gained from multivariate models, and the utility of a Bayesian Markov Chain Monte Carlo (MCMC) approach. This chapter presents a multivariate analysis of sexually selected weaponry, antlers in red deer, using data from a long-term study of a wild population of red deer. Using a Bayesian MCMC framework, the relationship between a component of fitness, male annual breeding success (ABS), and two antler traits (size (mass) and shape (the number of points, or form)) is estimated. Using a multivariate animal model to dissect these relationships revealed substantial positive environmental associations between each trait and ABS, presumably reflecting condition-dependence of both antler growth and the traits determining mating success. In contrast, a lack of genetic covariance between either trait and ABS suggested that neither would be predicted to evolve further via sexual selection. Furthermore, a significant difference between the genetic and the environmental multivariate gradients between antler form and fitness indicated a lack of causal effects on fitness. The analyses reveal a complex set of relationships not apparent at either a phenotypic or a univariate level, and suggest constraints to evolution despite the presence of genetic variance in the focal fitness component. This chapter also discusses advantages and problems associated with using multivariate quantitative genetic analyses to explore the process of selection in wild populations.
Evolutionary potential and constraints in wild populations
Authors: Teplitsky Céline , Robinson Matthew R. , Merilä Juha 
Published: August 2014

AbstractThis chapter asks: How can evolutionary potential be measured? The question is deceptively simple: whilst evolutionary potential is typically defined on a per-trait basis, it has become clear that the complex genetic architecture of quantitative traits requires other ways to quantify evolutionary potential and constraints. This chapter reviews knowledge about multivariate evolutionary potential in the wild and the extent to which genetic covariances, as summarized in the G-matrix, impact evolutionary trajectories of natural populations both in terms of rate and direction. In terms of constraints, genetic covariances among traits can slow down the rate of adaptation, and influence the direction of the response to selection. However, the constraints posed by genetic covariances are insurmountable only if G-matrices are stable. The chapter thus reviews firstly theoretical predictions about the stability of G in relation to selection, migration and drift, and secondly methods available to test differentiation among matrices. To date, a majority of studies imply conservatism of G-matrices; however, a couple of recent studies have revealed that differentiation of G-matrices among wild populations can also be very fast, especially during colonisation of new habitats. Furthermore, as an increasing number of methods have been proposed for comparing G-matrices, we assessed how these methods perform under different hypothetical scenarios. The chapter shows that limited statistical power could often lead to erroneous conclusion of matrix conservatism, suggesting caution is needed in interpreting the results of matrix comparisons. The chapter concludes by identifying areas in need of further research.
Phrase Structure and Argument Structure
Authors: Lohndal Terje 
Published: August 2014

AbstractThis book focuses on how syntax and meaning go together. It argues that two seemingly unrelated questions are actually intimately related: whether thematic arguments should be severed from the verb and whether there is a syntactic difference between specifiers and complements. Thus the book combines research in the domain of argument structure with research on phrase structure. It is argued that it is possible to create a mapping from syntax to logical form such that each syntactic Spell-Out domain corresponds to a conjunct at logical form. The book shows how one can adjust Spell-Out in order to achieve this, an operation which turns out to be closely related to whether or not the grammar distinguishes between specifiers and complements. An entire chapter is devoted to the latter issue, where it is shown that specifiers qua specifiers are not required by the grammar. The mapping is argued to be transparent in the sense that each conjunct at logical form is directly connected to a specific syntactic domain. The book closes with a discussion of compositionality in some detail, arguing that a semantics based on conjunction is compositional.
The Syntax‐Semantics Mapping
Authors: Lohndal Terje 
Published: August 2014

AbstractThe goal of this chapter is to tie Chapters 2 and 3 together and provide a syntax that maps transparently onto logical forms where all thematic arguments are severed from the verb. Specifically Lohndal argues that an argument is semantically tied to a head iff it is a sister of that head. The chapter starts out by presenting its syntactic assumptions before turning to the mapping hypothesis itself. A few alternative mapping hypotheses are also considered before the semantic composition operations are scrutinized. Lastly the chapter presents a number of syntactic consequences of the theory: Spell-Out, movement, linearization, thematic uniqueness, and agreement.
The interpretation of indefinites in future tense sentences: A novel argument for the modality of will?
Authors: Del Prete Fabio 
Published: August 2014

AbstractThe chapter considers two semantic issues concerning will-sentences: Stalnaker’s Asymmetry and modal subordination in Karttunen-type discourses. The former points to a distinction between will and modal verbs, seeming to show that will does not license non-specific indefinites. The latter, conversely, suggests that will-sentences involve some kind of modality. To account for the data, the chapter proposes that will is semantically a tense, hence it doesn’t contribute a quantifier over modal alternatives; a modal feature, however, is introduced in the interpretation of a will-sentence through a supervaluational strategy universally quantifying over possible futures. That this is not part of will’s lexical semantics is shown to have consequences that ultimately contribute to explain Stalnaker’s Asymmetry. Furthermore, that a modal quantification is present in the interpretation of a will-sentence is shown to imply the availability of modal subordination in Karttunen-type discourses.
Causal chains for futurates
Authors: Copley Bridget 
Published: August 2014

AbstractOne problem for accounts of future reference is the fact that there are different ways to refer to future times. In a strictly temporal theory of future reference, the differences must be temporal, and in a branching framework that treats future reference as quantifying over possible worlds, the differences must either be temporal or stem from the use of different sets of worlds. This chapter contrasts two different kinds of future reference: sentences with ‘real’ futures and futurate sentences, to argue that understanding the latter requires the notion of causal relations between events or event-like entities. Consequently, it is the causal relations inside the verb phrase that give rise to the future reference in futurates, rather than a temporal or branching future operator.
Markers of futurity and aspect in West Greenlandic
Authors: Trondhjem Naja 
Published: August 2014

AbstractOriginally Inuit languages had a temporal opposition between future and non-future. Over time, Iñupiaq has evolved an opposition between past, present, and future, while Inuktitut and West Greenlandic (WG) have retained the future/non-future opposition. This chapter will show that it is incorrect to describe WG as tenseless; WG has grammaticalized tense affixes. There are five such future-tense affixes: -ssa ‘future’, -niar ‘inevitable future’, -jumaar ‘vague future’, -ssamaar ‘planned future’, and -ler ‘near future’. The first three also have modal meanings: -ssa ‘should’, -niar ‘intention’, -jumaar ‘promise’. While, ssamaar has only one meaning, -ler has an additional three: two in the inner phasal aspect (‘begin’ and ‘be about to’), and one in outer phasal aspect (‘be about to’). This chapter shows that it is necessary to pay close attention to morphological structure, and to allow for the possibility that tense can be expressed by derivational affixes.
Balance Sheet Recessions and Time-Varying Coefficients in a Phillips Curve Relationship: An Application to Finnish Data
Authors: Juselius KatarinaM , Juselius Mikael 
Published: August 2014

Abstract
Edmund Phelps (1994) introduced a modified Phillips curve where the natural rate of unemployment is a function of the real interest rate instead of a constant. Koo (2010) argues that the effect of the interest rate on the macro economy is likely to be diluted during a balance sheet recession such as those recently seen in many countries. In the late 1980s, after having deregulated credit and capital movements, Finland experienced a housing boom which subsequently developed into a serious economic crisis similar to the recent ones. To learn from the Finnish experience we estimate the Phelps modified Phillips curve and use a Smooth Transition (STR) model to distinguish between ordinary periods and balance sheet recessions.
Fundamental Problems with Nonfundamental Shocks
Authors: Lütkepohl Helmut 
Published: August 2014

Abstract
Economic agents using information that is not incorporated in the econometric model is seen as a possible reason for why nonfundamental shocks are important in econometric models. Allowing for nonfundamental shocks in structural vector autoregressive (SVAR) analysis by considering moving average (MA) representations with roots in the complex unit circle is a possible response to the problem. Such models lead to nonlinear optimal forecast functions in general and are in this sense nonlinear models. A case is made for viewing nonfundamentalness as an omitted variables problem rather than a problem of MA roots in the unit circle. The omitted variables problem will always lurk in the background of SVAR analysis as well as other econometric studies and cannot be avoided. In SVAR analysis it is even more problematic than what the literature on nonfundamental shocks suggests.
Penalized Estimation of Semi-Parametric Additive Time-Series Models
Authors: Medeiros Marcelo C. , Mendes Eduardo F. 
Published: August 2014

AbstractThis paper studies oracle properties of ℓ1-penalized least squares estimator, such as the LASSO, in a semi-parametric regression setting with dependent data. We extend previous results in the literature of semi-parametric models and show that sparsity oracle inequalities for the LASSO also hold in a time-series environment. The results are valid even when the dimension of the model is (much) larger than the sample size and the regression matrix is not positive definite. Our results are derived when the nonparametric component is approximated by a linear combination of known basis functions (sieves), such that the approximating model is linear in the parameters. We advocate the use of a set of randomly generated logistic functions to approximate the nonparametric component of the model. Both simulations and an empirical exercise with Brazilian energy consumption data deliver promising results.
Asymmetric Dependence Patterns in Financial Returns: An Empirical Investigation Using Local Gaussian Correlation
Authors: Støve Bård , Tjøstheim Dag 
Published: August 2014

Abstract
A number of studies have provided evidence that financial returns exhibit asymmetric dependence, such as increased dependence during bear markets, but there seems to be no agreement as to how such asymmetries should be measured. We introduce the use of a new measure of local dependence to study this asymmetry. The central idea of the new approach is to approximate an arbitrary bivariate return distribution by a family of Gaussian bivariate distributions. At each point of the return distribution there is a Gaussian distribution that gives a good approximation at that point. The correlation of the approximating Gaussian distribution is taken as the local correlation in that neighborhood. The new measure does not suffer from the selection bias of the so-called conditional correlation in case of Gaussian data, and is able to capture nonlinear dependence. Analysing several financial returns from the US, UK, and German markets, we confirm and are able to explicitly quantify the asymmetry. Finally, we point out a number of possible extensions.
Bagging Constrained Equity Premium Predictors
Authors: Hillebrand Eric , Lee Tae-Hwy , Medeiros Marcelo C. 
Published: August 2014

AbstractThe literature on excess return prediction has considered a wide array of estimation schemes, among them unrestricted and restricted regression coefficients. We consider bootstrap aggregation (bagging) to smooth parameter restrictions. Two types of restrictions are considered: positivity of the regression coefficient and positivity of the forecast. Bagging constrained estimators can have smaller asymptotic mean-squared prediction errors than forecasts from a restricted model without bagging. Monte Carlo simulations show that forecast gains can be achieved in realistic sample sizes for the stock return problem. In an empirical application using the data set of Campbell and Thompson (2008), we show that we can improve the forecast performance further by smoothing the restriction through bagging.