Asexuals looking for sex: conflict between species and mate-quality recognition in sailfin mollies (Poecilia latipinna)

When two closely related species are sympatric the process of species recognition (identifying conspecifics) and mate-quality recognition (increased fitness benefits) can yield a conflict when heterospecifics resemble high-quality conspecifics. Conflict in species versus mate-quality recognition may serve as a possible mechanism for the persistence of unisexual, gynogenetic Amazon mollies (Poecilia formosa). Amazon mollies require sperm from closely related species (e.g., sailfin mollies, P. latipinna) to start embryogenesis but inheritance is strictly maternal. When choosing mates, male sailfin mollies from populations sympatric with Amazon mollies may rely on traits indicating species identity rather than those indicating mate quality. Conversely, males from allopatric populations may rely more on traits indicating mate quality. Previous work has found that male sailfin mollies in sympatry exhibit a significantly greater mating preference for female sailfin mollies over Amazon mollies compared to males in allopatry. In addition, male sailfin mollies prefer to associate with and produce more sperm in the presence of larger conspecific females, which are more fecund. We hypothesized that male sailfin mollies experience a conflict in species recognition and mate-quality recognition in the presence of Amazon mollies that are relatively larger than female sailfin mollies. To test this hypothesis, we paired males from sympatric and allopatric populations with a larger Amazon molly and a smaller female sailfin molly. We scored the number of mating attempts that males directed to conspecific and heterospecific females. Males in most sympatric and allopatric populations demonstrate no clear preference for conspecifics. In addition, we found some evidence for a difference in mating preference between allopatric and sympatric populations with males from allopatry showing a greater heterospecific mate preference. These results indicate a conflict between species and mate-quality recognition. In sympatry this conflict may contribute to the persistence of gynogenetic Amazon mollies.     

Effects of movement and eating on chemosensory tongue-flicking and on labial-licking in the leopard gecko (Eublepharis macularius)

Summary Two forms of lingual protrusion, tongueflicking and labial-licking, were differentially affected by combinations of movement and eating conditions in a eublepharid gecko (Eublepharis macularius). Tongue-flicking, in which the tongue contacts substrates beyond the lizard's body, occurred at increased rates during locomotion and during locomotion was significantly more frequent after eating than in a baseline condition. Labial-licking, in which a protruded portion of the tongue touches the labial, mental or rostral scales that surround the mouth, increased after eating. Unlike tongue-flick rates, by far the highest labial-lick rates were observed in stationary lizards after eating. The elevated tongue-flicking rates during movement after eating may be a manifestation of a postingestive chemosensory search for prey. In addition to grooming, several possible chemosensory functions of labial-licking are discussed, including gustatory sampling, sampling prey chemicals on the labials for transfer to the vomeronasal system, and redistribution of chemicals on the tongue to enhance transfer. It is suggested that labial-licking might help motionless lizards maintain vigilance for visual prey stimuli associated with the specific chemical prey cues. Another possible explanation for the increased labial-lick rate while motionless after eating is that prey chemicals induce tongue-flicking, but that the distance protruded is lessened and the tongue does not contact environmental substrates. Tongue-flicking while stationary is unlikely to lead to detection of additional prey and might incur detection by the lizard's predators or prey.     

Ant gardens: interspecific recognition in parabiotic ant species

 In French Guiana, parabiotic societies (natural mixed colonies) are frequently found in ant gardens. Crematogaster limata parabiotica (Myrmicinae), often associated with Camponotus femoratus (Formicinae), was found for the first time in parabiosis with ponerine ants: Pachycondyla goeldii and Odontomachus mayi. A detailed study of the relationships between Cr. l. parabiotica and O. mayi showed that each species is aggressive towards allospecific or conspecific individuals belonging to another colony, but tolerates allospecific individuals from the multi-species society. Studies of cuticular substances of the four ant species were made using gas chromatography. The results showed that each species, living alone or in parabiosis, possesses a specific chemical profile. Thus, the ants are able to recognise nestmate and non-nestmate individuals of the associated species, even though their cuticular profiles are different. The hypothesis that the nestmate allospecific profile is learned is suggested to explain this pattern of recognition. Received: 5 June 1996 / Accepted after revision: 17 October 1996     

Learning and natal host influence host preference,handling time and sex allocation behaviour in a pupal parasitoid

The host choice and sex allocation decisions of a foraging female parasitoid will have an enormous influence on the life-history characteristics of her offspring. The pteromalid Pachycrepoideus vindemiae is a generalist idiobiont pupal parasitoid of many species of cyclorrhaphous Diptera. Wasps reared in Musca domestica were larger, had higher attack rates and greater male mating success than those reared in Drosophila melanogaster. In no-choice situations, na?ve female P. vindemiae took significantly less time to accept hosts conspecific with their natal host. Parasitoids that emerged from M. domestica pupae spent similar amounts of time ovipositing in both D. melanogaster and M. domestica. Those parasitoids that had emerged from D. melanogaster spent significantly longer attacking M. domestica pupae. The host choice behaviour of female P. vindemiae was influenced by an interaction between natal host and experience. Female P. vindemiae reared in M. domestica only showed a preference among hosts when allowed to gain experience attacking M. domestica, preferentially attacking that species. Similarly, female parasitoids reared on D. melanogaster only showed a preference among hosts when allowed to gain experience attacking D. melanogaster, again preferentially attacking that species. Wasp natal host also influenced sex allocation behaviour. While wasps from both hosts oviposited more females in the larger host, M. domestica, wasps that emerged from M. domestica had significantly more male-biased offspring sex ratios. These results indicate the importance of learning and natal host size in determining P. vindemiae attack rates, mating success, host preference and sex allocation behaviour, all critical components of parasitoid fitness. Electronic Publication     

土壤遥感分类识别专家系统的结构设计

介绍了土壤遥感分类识别专家系统的设计原理与实现方法，阐述了土壤遥感分类识别专家系统的土壤分类决策判断树的构造原理，讨论了土壤遥感分类识别专家知识表示的基本原则和系统知识库中专家知识的组织方式，以及专家系统推理机的设计原理和推理规则的构建方法。系统采用压缩编码方式存储地学专题图形和遥感图像数据，具有数据与图像的存储更新、查询检索、分析处理、特征提取和信息输出等功能。该系统可以对遥感图像进行土壤类型的分类识别，并对分类精度进行监测与评价。用该系统对新疆天山北麓阜康试验区的土壤分类识别进行了试验研究，并对试验结果进行了讨论与评价。     

Attractive and repellent host odours guide ticks to their respective feeding sites

Summary. We have studied on-host behaviour of adults of the brown ear tick (Rhipicephalus appendiculatus Neumann, 1901) and the red-legged tick (R. evertsi Neumann, 1897), which prefer to feed mainly inside the ears and the anal regions of bovids respectively. Both species were found to be relatively successful in orienting toward and locating their respective feeding sites from different parts of the host body. Our observations suggested the operation of both avoidance (closer to the feeding site of the other) and attraction (closer to its own feeding site) responses of the ticks. In the laboratory, odour trapped from cattle ears attracted R. appendiculatus but repelled R. evertsi, whereas that from the anal region had an opposite effect. This odour-based push-pull pair of stimuli may largely account for efficient orientation behaviour of the two tick species to their respective feeding sites. We propose that such concurrent deployment of repulsive and attractive cues may be quite widespread among arthropods and related organisms that specialise on specific hosts or microenvironments in the performance of their biological functions.     

Does information of predators influence general wariness?

Antipredator behavior includes several qualitatively distinct activities, but few studies have determined the degree to which these activities are independent. If behaviors are not independent, then the nature of the relationship would illustrate potential performance constraints. We studied crimson rosellas (Platycercus elegans) and first focused on acoustic predator discrimination. We measured time allocation before and after playback of one of three experimental treatments (peregrine falcons—Falco peregrinus, wedge-tailed eagles—Aquila audax, and crimson rosellas) to determine whether or not rosellas discriminated predators from non-predators, and specifically whether or not they discriminated large from small predators. We then focused on the decision to flee. We experimentally approached subjects and measured the distance at which they oriented to us (alert distance) and the distance at which they fled (flight initiation distance; FID). We found that rosellas could distinguish among predators; however, there was no effect on general wariness as measured by FID. These two processes of antipredator behavior may, thus, be independent.     

Do echolocation calls of wild colony-living Bechstein's bats (Myotis bechsteinii) provide individual-specific signatures?

Social animals often use vocal communication signals that contain individual signatures. As bats emit echolocation calls several times per second to orient in space, these might seem ideal candidates for conveying the caller's individual identity as a free by-product. From a proximate perspective, however, coding of caller identity is hampered by the simple acoustic structure of echolocation signals, by their task-specific design and by propagation loss. We investigated the occurrence of individual signatures in echolocation calls in individually marked, free-living Bechstein's bats (Myotis bechsteinii) in a situation with defined social context in the field. The bats belonged to two different colonies, for both of which genetic data on relatedness structure was available. While our data clearly demonstrate situation specificity of call structure, the evidence for individual-specific signatures was relatively weak. We could not identify a robust and simple parameter that would convey the caller's identity despite the situation-specific call variability. Discriminant function analysis assigned calls to call sequences with good performance, but worsened drastically when tested with other sequences from the same bats. Therefore, we caution against concluding from a satisfactory discrimination performance with identical training and test sequences that individual bats can reliably be told apart by echolocation calls. At least the information contained in a single call sequence seems not to be sufficient for that purpose. Starting frequencies did give the best discrimination between individuals, and it was also this parameter that was correlated with genetic relatedness in one of our two study colonies. Echolocation calls could serve as an additional source of information for individual recognition in Bechstein's bats societies, while it is unlikely that a large number of individuals could be reliably identified in different situations based on echolocation alone.     

Loft features influence the processing of navigational information by pigeons

The present study evaluates the impact of lofts on the development of the navigational system of pigeons. A series of results obtained between 2000 and 2004 were analyzed. The H-loft was placed 10 m above the ground, with a ring format and seven windows all around it as well as three external aviaries that allowed birds to have a wide view of the outdoors and of the sky and knowledge of the wind dynamics. The L-loft was placed at ground level, with a single window transformed into an external aviary. The L-loft was protected from the wind by surrounding trees, reducing the ability of the pigeons to access the wind dynamics and also restricting their access to information regarding the outside area and the sky. In a preliminary analysis, we found the parameter of “vanishing time” to differ significantly between lofts in two of the five age classes. A thorough analysis of this parameter throughout the ontogenetic development of the birds demonstrated a pronounced improvement in the information-processing system with age, with adults vanishing quicker than younger birds, although an impairment of development occurred during the third month of age, perhaps due to a reorganization of the system. This result was obtained when the effect of lofts was considered in the different age classes. Results suggest that loft features are an important factor in the ability of the young pigeons to exploit navigational cues.     

Time course of pyrrolizidine alkaloid sequestration in <Emphasis Type="Italic">Longitarsus</Emphasis> flea beetles (Coleoptera,Chrysomelidae)

Summary. Several species of Longitarsus take up, metabolize and store pyrrolizidine alkaloids (PAs) from their host plants. In feeding experiments using radioactively labeled PAs of different types we examined the time course of the sequestration process in L. jacobaeae and L. aeruginosus. We found that adapted species efficiently store PAs for at least two weeks without major losses. During that time, there is virtually no change in the ratio of tertiary alkaloids to stored non-toxic N-oxides, regardless of chemical form fed to the beetles. This implies a transient N-oxidation process where the alkaloids are only temporarily accessible to the enzyme. A dissection experiment with L. aeruginosus six days after uptake of labeled PAs showed that the tertiary alkaloids are not found in the hemolymph but are stored in the elytra and other body compartments. This conforms with earlier experiments that localized the enzymes site of action in the hemolymph. Furthermore we show that different total alkaloid doses in the diet of L. jacobaeae and the potentially less adapted L. succineus do not affect the ratio of recovered N-oxides to tertiary molecules. Thus, the efficiency of the N-oxidizing enzyme is not dependent on the concentration of alkaloids offered.