Polyandry in the genus Apis, particularly Apis andreniformis

Using four polymorphic microsatellite loci, we found that four Apis andreniformis queens collected in Thailand each mated at least 10–20 times, producing an average relatedness, g _ww, of workers of 0.30 ± 0.007, and an average effective number of matings of 9.1 ± 2.2. The degrees of polyandry and intra-colonial genetic relatedness in A. andreniformis are similar to those in A. mellifera, slightly more than in A. florea, and up to 6 times less than in A. dorsata. We argue that while presently favoured hypotheses for the evolution of polyandry in monogynous social insects may adequately explain the evolution of up to five or six matings, they are inadequate to explain the extreme polyandry (10–60 matings) observed in Apis. One alternative possibility is that colony fitness is a non-additive function of the fitness of individual subfamilies. Such behavioral over-dominance may mean that queen fitness is increased by high levels of polyandry, which increase the probability of desirable combinations of worker genotypes occurring in one colony. The special attributes of honey bees which may lead to behavioral over-dominance include colony aggregation (which may increase the incidence of disease), and frequent long-distance migration. Received: 8 May 1996/Accepted after revision: 9 August 1996     

Variation among populations of the sailfin molly in the rate of concurrent multiple paternity and its implications for mating-system evolution

We examined patterns of concurrent multiple mating in a live-bearing poeciliid fish, the sailfin molly (Poecilia latipinna). We tested whether the probability of multiple paternity was related to female body size or fertility and whether the rate of multiple paternity varied among four populations that differed in their distributions of female body size and fertility. We analyzed data on mother and offspring genotypes for three polymorphic allozymes by three techniques, including a maximum-likelihood estimator that accounts for sampling error in both parental and offspring allele frequencies. The estimated rate of multiple paternity varied between 0.09 and 0.85, and the rate in one population varied seasonally between 0.33 (spring) and 0.85 (autumn). The variation in these rates was not associated with variation in body-size distributions among populations but was closely associated with variation in size-specific fertility: populations with greater variation in female fertility had higher multiple-paternity rates. Within two populations, logistic regression revealed that individual females of larger body size and greater size-specific fertility were more likely to carry multiply sired broods. This result is consistent with observations made in one of the populations 5 years earlier. In general, the results strongly suggest that the mating system varies markedly among conspecific populations of sailfin mollies and that larger, more fertile females are the objects of intermale competition. Received: 6 May 1996 / Accepted in revised form: 5 December 1996     

Prenatal diagnosis in multiple gestation: 20 Years' experience with amniocentesis

Three hundred and thirty-nine cases of multiple gestation underwent prenatal diagnosis by amniocentesis. The spontaneous abortion rate (to 28 weeks) in this group was 3.57 per cent compared with our singleton abortion rate of 0.60 per cent. The perinatal mortality rate (PMR) and prematurity rate were not different from the singletons, and compared favourably with the PMR reported in the literature for multiple gestations which did not undergo any intervention during pregnancy. This increased abortion rate following amniocentesis may only represent the increased natural loss rate in multiple gestations, and not indicate any increased risk added by the procedure.     

Mating behavior of female rock shrimp Rhynchocinetes typus (Decapoda: Caridea)—indication for convenience polyandry and cryptic female choice

While studies on a wide diversity of organisms have demonstrated the importance of female behavior during matings, in crustacean studies, a strong bias towards male mating behavior prevails. Reproductively mature rock shrimp (Rhynchocinetes typus) exist as several ontogenetic stages that differ in their morphological and physiological capacities. In natural populations, the majority of males are in early ontogenetic stages (termed typus), many are in intermediate stages (intermedius), and few are in the terminal molt stage (robustus). Dominant robustus males, which have already demonstrated their biological fitness by surviving to this stage, have previously been shown to have a higher potential than subordinate typus males to defend receptive females against other males, and fertilize the entire clutch of a female. While females should thus show a preference for robustus males, they nevertheless frequently receive sperm from typus males. These observations suggested that females might have mechanisms to discriminate against sperm from subordinate males. In laboratory experiments, we observed that females avoided being seized by typus males for longer time periods in the absence of robustus males than in their presence. Following seizure, females that were initially held by typus males, required more time to initiate spawning than those held by robustus males. Many typus males transferred spermatophores to females before these started to spawn while robustus males waited until females began to spawn before they transferred spermatophores. Females manipulated spermatophores received from typus males for long time periods (minutes), but not those they received from robustus males. By accepting sperm from subordinate typus males, females may avoid further harassment (convenience polyandry), but they subsequently may discriminate against these subordinate males by delaying spawning and removing their sperm. These observations suggest that female behavior influences the outcome of matings, favoring fertilization of eggs by sperm from dominant males. Convenience polyandry and cryptic female choice may be common in other crustaceans as well.Electronic Supplementary Material Supplementary material is available in the online version of this article at .Communicated by T. Czeschlik     

Task specialization in a wild bee,Apis florea (Hymenoptera: Apidae), revealed by RFLP banding

Workers in a wild in situ colony of the dwarf honey bee, Apis florea, were observed undertaking the following behavior: liquid foraging, pollen foraging, guarding, stinging, fanning and wagging abdomen. Bees of each behavioral class were separately collected and frozen. Collections were made over a period of 10 days. Random samples of brood and workers were also collected. DNA was extracted from each bee and fingerprinted using a probe of unknown sequence obtained from an A. mellifera genomic library. Patterns of fingerprints (Fig. 1) were dissimilar among behavioral classes (Tables 1 and 2), strongly suggesting a genetic component to division of labor in this species. This result supports similar findings in A. mellifera in a species that is not troubled by many of the experimental difficulties inherent in A. mellifera. Correspondence to: B.P. Oldroyd     

Multiple sexual advertisements honestly reflect health status in peacocks (Pavo cristatus)

The evolution of multiple sexual traits remains controversial and poorly understood in evolutionary biology. In many bird species, males exhibit complex courtships involving feather ornaments and behavioral display. Multiple traits may convey information on the genetic and phenotypic quality of males. In particular, fixed characters, such as feather ornaments (produced once a year during the annual molt in many bird species) might convey information about past male condition (at the time of trait development); whereas flexible traits such as behavioral displays should be sensitive to present condition. Here we show that both flexible behavioral displays and fixed feather ornaments of peacocks, used by females to choose a mate, honestly reflect health status. Correlative data showed that peacocks with high display rate (the number of behavioral displays per hour) and a large number of tail eyespots had low levels of circulating heterophils, suggesting better health status. Experimental activation of the immune system, through LPS injection, significantly reduced display rate compared to a control group. However, the sensitivity of a male display rate to the immune challenge was dependent on the number of tail eyespots: males with higher number of tail eyespots were better able to cope with the experimental immune challenge, and maintained their display rate at levels closer to the levels performed before the immune activation. These results are consistent with the idea that multiple signaling might enhance information reliability.     

Looking on the bright side: females prefer coloration indicative of male size and condition in the sexually dichromatic spadefoot toad, <Emphasis Type="Italic">Scaphiopus couchii</Emphasis>

Females across many taxa commonly use multiple or complex traits to choose mates. However, the functional significance of multiple or complex signals remains controversial and largely unknown. Different elements of multiple or complex signals may convey independent pieces of information about different aspects of a prospective mate (the “multiple messages” hypothesis). Alternatively, multiple or complex signals could provide redundant information about the same aspect of a prospective mate (the “redundant” or “back-up” signal hypothesis). We investigated these alternatives using spadefoot toads, Scaphiopus couchii. Spadefoot toads primarily use calls to attract their mates, but males also exhibit sexually dimorphic coloration. We investigated whether male coloration is indicative of male size, condition, or infection status by a socially transmitted monogenean flatworm. We found that male coloration and dorsal patterning predicts male size and condition but not infection status. Moreover, when we presented females with a choice between a bright male model and a dark male model, we found that females preferred the bright model. Because aspects of males’ calls are also associated with male size and condition, we conclude that coloration is a potentially redundant indicator of male phenotype. We suggest that coloration could enhance mate choice in conjunction with male calling behavior by providing females with a long distance cue that could enable them to identify prospective mates in a noisy chorus environment where the discrimination of individual calls is often difficult. Generally, such redundant signals may facilitate mate choice by enhancing the quality and accuracy of information females receive regarding prospective mates.     

环保产业投入产出评价模型

本文在GNP指标基础上提出了NCV指标 ,其主要作用是同时考察经济增长和环境代价。对环境代价的测量目前还没有一个完全可行的方法。对此 ,文章提出生态乘数概念和自然资源再生周期函数 ,旨在提供一个定量分析环境污染的思路。     

Sperm competition and ejaculate investment in red squirrels (<Emphasis Type="Italic">Tamiasciurus hudsonicus</Emphasis>)

Sperm competition is widespread in mammals and occurs when ejaculates from two or more males compete within the female’s reproductive tract to fertilize the ova. Enlarged testes are associated with sperm competition because they produce sperm, but the accessory glands produce fluids and proteins that are also important for fertilization success. Sperm morphology can also have consequences for fertilization success because of its influence on sperm motility. Red squirrels engage in multiple mating, and thus sperm competition is likely. Here, we assess levels of multiple paternity in a natural population of red squirrels, test the prediction that testis size is correlated with size of the accessory glands and sperm morphometry, and test the prediction that ejaculate investment is condition-dependent. Five of six litters (83%) showed evidence of multiple paternity, indicating that sperm competition is likely to have occurred. Testis size was correlated with the size of all three accessory glands (prostate, seminal vesicle, epididymides), and there was a generally positive relationship between the size of the accessory glands and sperm length. Sperm morphology showed significant variation in size and shape among individual male squirrels. There was no evidence of condition dependence of testis size or the size of the accessory glands, but sperm midpiece length was negatively related to body condition. Further work should include determining the fitness consequence of variation in sperm morphometry, testis size, and accessory gland size, and determining the effects of variation in ejaculate investment on sperm motility.     

Resource distributions affect social learning on multiple timescales

We study how learning is shaped by foraging opportunities and self-organizing processes and how this impacts on the effects of “copying what neighbors eat” on multiple timescales. We use an individual-based model with a rich environment, where group foragers learn what to eat. We vary foraging opportunities by changing local variation in resources, studying copying in environments with pure patches, varied patches, and uniform distributed resources. We find that copying can help individuals explore the environment by sharing information, but this depends on how foraging opportunities shape the learning process. Copying has the greatest impact in varied patches, where local resource variation makes learning difficult, but local resource abundance makes copying easy. In contrast, copying is redundant or excessive in pure patches where learning is easy, and mostly ineffective in uniform environments where learning is difficult. Our results reveal that the mediation of copying behavior by individual experience is crucial for the impact of copying. Moreover, we find that the dynamics of social learning at short timescales shapes cultural phenomena. In fact, the integration of learning on short and long timescales generates cumulative cultural improvement in diet. Our results therefore provide insight into how and when such processes can arise. These insights need to be taken into account when considering behavioral patterns in nature.