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821.
The difficult reconstruction of the evolutionary history of the major surface protein gene oprF highlighted an adaptive radiation in the Pseudomonas fluorescens group. The recent work of Hao (2013) showed that partial recombination events in oprF gene occurred specifically in a P. fluorescens lineage under ecological niche segregation. So, I suggest that identification of lineage-specific fine-scale recombination may be a way to detect putative adaptive radiation in bacteria.  相似文献   
822.
Women in Kinshasa, Democratic Republic of Congo are increasingly entering new professions partly due to an increase in higher education levels. In so doing, and as they become more visible in political and economic spheres, women are subjected to new forms of moral suspicion. While women have historically maintained a strong presence in the informal sector, such as commerce, new urban modes of employment dictate new kinds of visibility. It is within this context that notions of femininity and female virtue in Kinshasa continue to be redefined. This article explores several modes of employment for women, such as money-changing, journalism, and politics as they relate to local concepts of encadrement (supervision) and débrouillardisme (resourcefulness). Further, it also examines the threat that a woman's social network outside of her kin poses to men, as well as how women's participation in the economic sphere can motivate distrust between the genders.  相似文献   
823.
We tested the ability of a Euclidean algorithm to predict attraction to potential mates—a relatively upstream domain in the temporal sequence of the mating process. Participants in two studies reported their ideal mate preferences using a 23-item preference instrument. Separately, they rated their attraction to profiles of potential mates that varied on those 23 dimensions. Study 1 (N = 522) found that Euclidean distances predicted attraction to potential mates both in terms of (1) overall mate value and (2) unique mate value. Study 2 (N = 411) replicated these effects and further found that Euclidean mate values discriminatively predict between short- and long-term attraction. Across both studies, a Euclidean model outperformed a variety of alternative models for predicting attraction to potential mates. These results suggest that a Euclidean algorithm is a good model for how multiple preferences are integrated in mate choice.  相似文献   
824.
Why do flowers of a hummingbird-pollinated mistletoe face down?   总被引:3,自引:1,他引:2  
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825.
826.
Ultraviolet (UV) colour patterns, particularly those deriving from surface structures, serve a role in sexual signalling and mate choice in a range of animal groups. In the butterfly Colias eurytheme (Pieridae), male-limited iridescent UV functions in species recognition, and has potential as an intraspecific sexual signal of mate quality. I compared the dorsal colouration and body size of males discovered ‘in-copula’ (N = 95) with a random sample of free-flying individuals (N = 129), both collected from a high density agricultural population located in Chandler, U.S.A. Despite reasonable variance in each trait, I found no among-group differences in UV characters (brightness, hue and angular visibility) or in the coincident pigmentary yellowish-orange (brightness and saturation). Statistical power was sufficient to detect all but the smallest among-group differences, and there was a marginally significant tendency for in-copula males to be larger. These data do not support the hypothesis for intraspecific female choice upon male dorsal colouration. However, I discuss how the density and apparently very young age of individuals in the sampling population may have pre-disposed this result, and thus, how sexual selection on male colouration may operate in a density dependent manner.  相似文献   
827.
“Peering”—close-proximity staring at the mouth of another—was observed in ten (three males and seven females) mature (at least 7 years old) bonobos (Pan paniscus) living in three social groups at the San Diego Zoo and Wild Animal Park. Instantaneous scan samples, taken at 2-min intervals, over a three-and-a-half year period, yielded 617 observations of peering (1.4 per observation hour). Food was exchanged in only 15 of these scans. Peering was most often performed by younger animals and was primarily directed toward older females (“matrons”). In a given dyad, the animal more likely to peer at the other was also more like to both peer and be peered at if they frequently groomed and infrequently displayed aggression at a given female. An adolescent male showed the highest frequency of peering when living with two older females, but dropped to adult male levels when later housed with two younger (albeit mature) females. A reversal in which animal was more likely to peer, follow, and groom occurred in one female dyad, after the birth of the younger animal's first infant. After a similar birth in the other group, no such changes were observed. We discuss how these and related findings, in conjunction with what is known of the social structure of this species, suggest that one possible function of peering in bonobos may be as a signal acknowledging female status.  相似文献   
828.
The mutant brevistylis of Oenothera (Onagraceae) is characterized mainly by malformations of the style and by female sterility. Morphological features of the style and stigmas, such as the length of the style and the number, size, and shape of the stigmatic lobes is very variable. The abscission layer between ovary and style is missing and the placenta with ovules is protruded into the style. An interpretation of the disturbances in development observed in the br/br homozygotes is presented. The primary influence of br on development is proposed to be a general delay in meristematic growth, followed by irregularities in the timing of morphogenetic events which in turn lead to the anomalies in morphology of style and stigmas.  相似文献   
829.
A variety of characteristics were studied in populations of the onion root maggot, Hylemya antiqua, to determine the extent to which the age of the female producing a batch of eggs might affect heterogeneity in her offspring. Early-born offspring were found to be reproductively most successful. They had the longest mean expectation of life, a relatively low mortality rate into mid-life, the highest average fecundity, the highest mean rate of egg production, and they produced the highest percentage of female offspring. On the other hand, mid-born offspring were hardiest. They also had a long mean expectation of life, comparable to that for early-born offspring but, in addition, they had the lowest sustained mortality rate and the greatest ability to survive food stress. Their robustness may have been acquired at the expense of certain reproductive capabilities however, in that their average fecundity was lower than their early-born siblings', and their rate of egg production was more variable. Late-born offspring were the most mortality-prone and the least fecund, but they had the shortest mean generation time. These differences must be evaluated in terms of their effects on the rate of natural increase and on population growth. Maternal age was found to influence pupal size, although the provenance groups differed significantly from each other and, in fact, showed opposite trends within their respective cohort groups. Size itself, and the ability of a species to alter the size at which it pupates, may be characteristics which have evolved to fit a specific set of environmental conditions.  相似文献   
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