The potential for floral evolution in response to competing selection pressures following the loss of hawkmoth pollination in Ruellia humilis.

Premise: In the absence of hawkmoth pollinators, chasmogamous (CH) flowers of Ruellia humilis self-pollinate by two secondary mechanisms. Other floral visitors might exert selection on CH floral traits to restore outcrossing, but at the same time preferential predation of CH seeds generates selection to increase the allocation of resources to cleistogamous (CL) flowers.

Methods: To assess the potential for an evolutionary response to these competing selection pressures, we estimated additive genetic variances ( ) and covariances for 14 reproductive traits and three fitness components in a Missouri population lacking hawkmoth pollinators.

Social jobs and the returns to drinking.

We uniquely show that the returns to drinking in social jobs exceed those in non-social jobs. The higher returns remain when controlling for worker personality, when including individual fixed effects and in a series of robustness exercises. This showing fits the hypothesis that drinking assists the formation of social capital, capital that has greater value in social jobs.

Genetic and environmental integration of the hawkmoth pollination syndrome in Ruellia humilis (Acanthaceae).

Background And Aims: The serial homology of floral structures has made it difficult to assess the relative contributions of selection and constraint to floral integration. The interpretation of floral integration may also be clouded by the tacit, but largely untested, assumption that genetic and environmental perturbations affect trait correlations in similar ways. In this study, estimates of both the genetic and environmental correlations between components of the hawkmoth pollination syndrome are presented for chasmogamous flowers of Ruellia humilis , including two levels of control for serial homology.

Did liberalising bar hours decrease traffic accidents?

Legal bar closing times in England and Wales have historically been early and uniform. Recent legislation liberalised closing times with the object of reducing social problems thought associated with drinking to "beat the clock." Indeed, using both difference in difference and synthetic control approaches we show that one consequence of this liberalisation was a decrease in traffic accidents.

An exact form of the breeder's equation for the evolution of a quantitative trait under natural selection.

Starting with the Price equation, I show that the total evolutionary change in mean phenotype that occurs in the presence of fitness variation can be partitioned exactly into five components representing logically distinct processes. One component is the linear response to selection, as represented by the breeder's equation of quantitative genetics, but with heritability defined as the linear regression coefficient of mean offspring phenotype on parent phenotype. The other components are identified as constitutive transmission bias, two types of induced transmission bias, and a spurious response to selection caused by a covariance between parental fitness and offspring phenotype that cannot be predicted from parental phenotypes.

BIPARENTAL INBREEDING DEPRESSION IN THE SELF-INCOMPATIBLE ANNUAL PLANT GAILLARDIA PULCHELLA (ASTERACEAE).

Biparental inbreeding is thought to be a common feature of plant populations with restricted pollen dispersal. It is generally assumed that the inbreeding depression frequently observed to accompany self-fertilization can be extrapolated to the lesser degrees of consanguinity involved in biparental inbreeding, but this is virtually untested. To test this assumption, seeds collected from a single natural population of the self-incompatible annual Gaillardia pulchella were used to generate full-sib families derived by crossing either noninbred full-sibs (inbred families) or noninbred nonrelatives (outbred families).

SEXUAL SELECTION BY THE HANDICAP MECHANISM.

The handicap mechanism of sexual selection by female choice has been strongly criticized because it does not cause sexual selection to reinforce viability selection and it cannot account for the origin of mating preferences. However, several models indicate that the handicap mechanism can have important effects when operating in conjunction with Fisher's mechanism in polygynous populations. These models have been criticized because they require that fitness remains heritable indefinitely.

CLINAL VARIATION ASSOCIATED WITH EDAPHIC ECOTONES IN HYBRID POPULATIONS OF GAILLARDIA PULCHELLA.

The variety pulchella of the outcrossing annual plant species Gaillardia pulchella consists of two edaphic races in central Texas which are divergent for one morphological and four electrophoretic characters. Reduced pollen stainability in F hybrids suggests the races are also divergent in chromosome structure. The recent proliferation of this species on roadsides and in pastures has led to hybridization between these races.

ASSOCIATIONS BETWEEN ALLOZYME FREQUENCIES AND SOIL CHARACTERISTICS IN GAILLARDIA PULCHELLA (COMPOSITAE).

Selection favoring different alleles in different environments frequently has been suggested as an explanation for allozyme variation within and among populations. This hypothesis predicts that allozyme frequencies will be correlated with environmental variables. Previous studies on allozyme frequency-environment covariation in plants often have relied on qualitative assessments of the environment and have emphasized highly autogamous species.