Darwin's ‘mystery of mysteries’: the role of sexual selection in plant speciation

Sexual selection is considered one of the key processes that contribute to the emergence of new species. While the connection between sexual selection and speciation has been supported by comparative studies, the mechanisms that mediate this connection remain unresolved, especially in plants. Similarly, it is not clear how speciation processes within plant populations translate into large-scale speciation dynamics. Here, we review the mechanisms through which sexual selection, pollination, and mate choice unfold and interact, and how they may ultimately produce reproductive isolation in plants. We also overview reproductive strategies that might influence sexual selection in plants and illustrate how functional traits might connect speciation at the population level (population differentiation, evolution of reproductive barriers; i.e. microevolution) with evolution above the species level (macroevolution). We also identify outstanding questions in the field, and suitable data and tools for their resolution. Altogether, this effort motivates further research focused on plants, which might potentially broaden our general understanding of speciation by sexual selection, a major concept in evolutionary biology.     

A Sense of Belonging and Exclusion: ‘Touchability’ and ‘Untouchability’ in Tamil Nadu

In India, touch is a prime marker of status and social relations. Those who are impure are ‘untouchable’,1 The terms ‘Untouchable’ and ‘Untouchability’ have been abandoned due to the humiliating meaning these terms confer, therefore I use them in inverted commas. The politically correct and common terms today are Scheduled Castes, in short sc, or Dalits, or sometimes Harijan. I use them here synonymously. but those who are of a relatively higher purity are also, depending on the context, either ‘untouchable’ or ‘touchable’ only under certain fixed rules. In this paper, I will explore the contexts in which body contact and touch can be part of personal relations. I describe how these body contacts signify important social relations and establish community identity. Further, I will analyse how patterns of body contact on the one hand change during childhood, and on the other hand produce changes in the status of a social persona. The last point to be investigated is the meaning of touch as a sign for public representations.     

Sex in the morning or in the evening? Females adjust daily mating patterns to the intensity of sexual harassment

Selection on males to mate at a higher rate than females often results in male harassment of females and counteracting female responses. When the reproductive value of copulation changes over time, these mating strategies are expected to be time dependent. Here, we demonstrate that variation in the intensity of male harassment leads to drastic changes in female daily mating patterns. In feral populations of fowl Gallus gallus domesticus, male harassment is intense, particularly in the evening when inseminations are most likely to result in fertilization. We experimentally manipulated the intensity of male harassment through similar-sized groups of different sex ratios. Male mating propensity was always higher than females', particularly in male-biased groups and in the evening, when males were closer to and more likely to approach females. Females counteracted male harassment by escalating resistance to mating and--crucially--by shifting their daily mating pattern: in strongly female-biased groups with relaxed sexual harassment, females solicited sex in the evening, while in male-biased groups, they solicited sex in the morning, thus avoiding harassment in the evening. Together, these results indicate that intersexual conflict may occur not only over mating rates but also over when in the day to copulate.     

‘A Culture of Immediatism’: Co-optation and Complicity in Post-war Angola

This article explores the notion of a ‘culture of immediatism’ that characterises the current political and socio-economic environment of Angola, according to residents of its capital, Luanda. Analysing the material and symbolic affects of the post-war economic boom in the lives of ‘ordinary’ citizens, the article proposes to read the discourses and practices deployed on the ideological terrain of ‘immediatism’ as renegotiations of hegemony. By ethnographically unpacking the ‘aesthetics of power', I sketch out the contours of hegemony to see how power relations change in practice over time. This then sheds new light on the social processes involved in rapid economic change and contemporary, ‘neo-authoritarian’ statecraft, balancing the standard ‘clientelist’ account of power in post-war Angola.     

Women’s sexual strategies in pregnancy

Humans exhibit an unusual pattern of sexual behavior compared to other mammalian females. Women's extended sexuality has been hypothesized to be related to a variety of possible benefits, especially non-genetic reproductive benefits, such as securing male investment via reinforced pairbonds or paternity confusion. But sexual behavior also comes at a cost, particularly for pregnant women, in terms of energetic costs, potential disease, and possible harm to the fetus. We hypothesize, therefore, that sexual behavior in pregnant women should reflect adaptive strategies and that pregnant women will be particularly strategic about their sexual behavior in order to maximize potential benefits while minimizing potential costs. One hundred twelve pregnant women completed a survey of their partners' qualities and their sexual desires toward their primary partners and men other than their primary partners. Results showed that women's perceptions of relationship threat positively predicted sexual desire for primary partners, while their perceptions of their partner's investing qualities negatively predicted sexual desire for extra-pair mates. These qualities, as well as cues to partner's genetic quality and gestation age, also interacted in ways that suggest that pregnant women's sexual desires are sensitive to cues of future investment and relationship stability.     

Kinetics of degradation of ‘short-’ and ‘long-lived’ proteins in cultured mammalian cells

Two distinct classes of protein referred to as short- and long-lived (Poole and Wibo, 1973) were found in pulse-chased HeLa S-3 and BHK 21/C13 cells. From experiments with pulse times ranging from 1 min to 20 h, a clear inverse correlation emerged between the pulse length and the percentage of protein which was hydrolysed intracellularly in the first h of chase. Using a 5 min pulse labelling with ³H-leucine, cells were either harvested immediately or after a 2 h chase. Approximately 35% of the label incorporated by cells was lost in a 2h chase; however, electrophoretic separation of cytosol and residual cytoplasmic fractions revealed no significant alteration in their protein profiles. The technique of selectively labelling ‘short’ and ‘long-lived’ proteins, which implies qualitative differences between them, is more readily interpreted as an artificial polarisation of a declining statistical probability curve of proteolysis with time which is similar for all nascent proteins.     

Inversion of ‘fluorescent’ segment in chromosome 3: A polymorphic trait

Summary The frequency of the inversion of fluorescent constitutive heterochromatin in chromosome 3 was the same in a sample of 370 retarded persons as in a sample of 222 mentally normal men. It can be concluded that this inversion is not associated with mental retardation. This variant is more common (4%) in the Canadian population we studied than in samples reported by most other authors (0–1.7%). Possibly the founder effect could play a role in the differences. Two cases of homozygotes for this inversion were identified.     

Species-specific ‘fingerprints’ of deer in China

State governments in China have laid down laws for protecting rare and endangered species, but the effective protection depends on accurate species identification. Although DNA fingerprinting has appeared in court as legal evidence for many years, it is unsuitable for species identification as previous multilocus probes produce individual-specific fingerprints. This study outlines the development of a new species-specific probe – the pta₂ probe. Using this oligonucleotide probe, the identification of all deer species in China is made possible by species-specific fingerprints. Material evidence can then be provided to any judicial organization, which will have a profound effect on the criminal activities of poachers, thereby helping to protect wild animals and conserve biodiversity. Interestingly, the pta₂ probe can also reveal the gender of detected deer species.     

A constructional account of French -clé ‘key’ and Dutch sleutel- ‘key’ as in mot-clé / sleutelwoord ‘key word’

The article studies the status of French clé ??key?? and Dutch sleutel ??key?? which are recurrent in complex nouns such as mot-clé / sleutelwoord ??keyword??, notion-clé / sleutelbegrip ??key notion?? and figure-clé / sleutelfiguur ??key figurè. In spite of the semantic similarities between the two elements, both occurring in similar compound-like constructions, it is shown that the degree of cohesion of N-clé and sleutel-N widely differs. More particularly, whereas sleutel forms cohesive NN compounds, clé can be observed in adjectival contexts, in the same way as its English counterpart key (e.g. un r?le absolument clé ??an absolutely key rolè??, ce livre est absolument clé ??this book is absolutely key??, etc.). This paradox is dealt with within the theoretical framework of Construction Grammar.     

Patterns of injury in zoo-housed spider monkeys: A problem with males?

Aggression among wild spider monkeys is most frequently reported to occur between the sexes, with adult males directing aggression towards adult females and the aggression is normally non-injurious. After two severe instances of aggression in the group of spider monkeys housed at Chester Zoo, we developed a questionnaire to investigate the frequency, direction and possible reasons for aggression in zoo-housed spider monkeys. We sent our questionnaire to 55 zoos worldwide and obtained records from 26 groups, which yielded detailed accounts of 143 aggressive incidents: 56 events for the actors and 127 events for the targets of aggression. We found that zoo-housed spider monkeys are predominantly maintained in small social groups, with a single adult male, two adult females and their offspring. Of the aggression reported, 23.1% of incidents resulted in severe or lethal injuries. Adult males were the most frequent actors of aggression and accounted for 66.7% of incidents. Six cases of male–male aggression were lethal. The most striking pattern was that adult males directed aggression towards non-adult males more than any other age/sex category. The most frequently reported context of aggression was tension between adult and non-adult males. These findings contradict previous reports from wild spider monkeys where female-directed male aggression is most frequently reported. In light of our findings, we recommend that males form the core of the group and that females be relocated among groups to reflect the wild condition of male philopatry and female dispersal. In addition, enclosure design should allow opportunities for the monkeys to segregate themselves from other group members, simulating fission, which is a conflict management strategy for avoiding aggression in wild spider monkeys.     

A ‘WATCH’ census of common British butterflies

In summer 1981, members of WATCH made a quantitative survey of common butterflies throughout Britain. Adult numbers were recorded along standardized transects on 670 sites, covering most commonplace biotopes. Butterflies were identified into families, except for five conspicuous species.

Ten common biotopes were sufficiently well sampled for general conclusions to be made about their value. Although garden flowers attracted the few species of butterfly that are very mobile, sedentary species were virtually absent from gardens especially in urban areas. Improved pasture also contained few sedentary species, but road verges and woods held moderate densities. Abandoned railway tracks and wasteland supported large numbers of common butterflies, but the highest counts were made in unimproved pasture. Numbers along hedges differed little from the open fields that they bordered.

The method was modified in 1982 so that sponsored counts could be made in the richest biotopes. These raised about £4000 for conservation.     

A texture-processing model of the ‘visual sense of number’

It has been suggested that numerosity is an elementary quality of perception, similar to colour. If so (and despite considerable investigation), its mechanism remains unknown. Here, we show that observers require on average a massive difference of approximately 40% to detect a change in the number of objects that vary irrelevantly in blur, contrast and spatial separation, and that some naive observers require even more than this. We suggest that relative numerosity is a type of texture discrimination and that a simple model computing the contrast energy at fine spatial scales in the image can perform at least as well as human observers. Like some human observers, this mechanism finds it harder to discriminate relative numerosity in two patterns with different degrees of blur, but it still outpaces the human. We propose energy discrimination as a benchmark model against which more complex models and new data can be tested.     

Innatism in the Anthropology of A. L. Kroeber: A Critique of ‘the Boasian Paradigm’

Basing his analysis on Kroeber's ‘The superorganic’ (1917 Kroeber, A. L. 1917. The superorganic.. American Anthropologist, 19: 163–213. [Crossref] [Google Scholar]) and ‘Eighteen professions’ (1915 Kroeber, A. L. 1915. Eighteen professions.. American Anthropologist, 17: 283–88. [Crossref] [Google Scholar]), Derek Freeman has put forward the notion of a ‘Boasian paradigm’, whereby Kroeber is alleged to have perpetuated the biology/culture split suggested by Boas. I argue, instead, that there is a strong innatist element in Kroeber's writings throughout his long career; and that the articles noted above need to be placed in the social and intellectual contexts of their time, particularly the encroachment of the eugenics movement on social theory and its application to immigration restriction.