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1.
The degree of intergradation between two species of Sulawesi macaques,Macaca tonkeana andM. hecki, was studied by examining the diagnostic external characteristics of more than 100 monkeys kept as pets by natives. Two possible hybrid monkeys were found and both originated from the borderland between the two species, located in the most proximal region of the northern peninsula of Sulawesi. The previously postulated wide area of integradation between the two species at the possible contact zone was, however, not recognized, and typical examples oftonkeana orhecki were found to be present on the two sides of a narrow “hybrid” zone which was defined by direct observations. Furthermore, despite considerable individual variations, we were able to allocate most monkeys to one or other of the species. Each of ten external characteristics of the members of both species more or less encompassed the individual variations, but may undergo changes with the development of the monkeys. The mechanisms of reproduction of hybrid monkeys and the maintenance of differences between the species are discussed.  相似文献   

2.
The purpose of this study was to develop a model to predict electroshock‐induced mortality in embryos of freshwater fishes. Herein, electroshock‐induced mortality was evaluated for sauger Sander canadensis and rainbow trout Oncorhynchus mykiss, and results were combined with published results obtained for eight other species in studies that used consistent methodology. The model was based on embryo diameter (1·1–4·1 mm among species), the most sensitive stage of embryonic development (near completion of epiboly for all species), and mortality (to hatching or eyed stage) after exposure to a homogeneous electric field [direct current (DC) or 60 Hz pulsed DC (PDC)]. Embryo diameter was positively related to electroshock‐induced mortality for DC (P < 0·001) and 60 Hz PDC (P < 0·05). Results suggested that vulnerability to electroshock‐induced mortality was related to physical characteristics (i.e. size) of embryos rather than species differences, and indicated that prediction of vulnerability in untested species is possible. This is particularly important for protection of endangered species, and those species with larger embryo sizes may be at most risk from electroshock. Conversely, results also suggested that it may be possible to assist in removal of invasive non‐native fish species with large embryo diameters (e.g. O. mykiss) by application of electroshock to target and kill embryos of these species in some freshwater habitats.  相似文献   

3.
A population dynamic model of Batesian mimicry, in which populations of both model and mimetic species were considered, was analyzed. The probability of a predator catching prey on each encouter was assumed to depend on the frequency of the mimic. The change in population size of each species was considered to have two components, growth at the intrinsic growth rate and carrying capacity, and reduction by predation. For simplicity in the analyses, three assumptions were made concerning the carrying capacities of each population: (1) with no density effects on the mimic population growth rate; (2) with no density effects on the model species; and (3) with density effects on both species. The first and second cases were solved analytically, whereas the last was, for the most part, investigated numerically. Under assumption (1), two stable equilibria are possible, in which both species either coexist or go to extinction. Under assumption (2), there are also two stable equilibria possible, in which either only the mimic persists or both go to extinction. These results explain the field records of butterflies (Pachliopta aristolochiae and its mimic Papilio polytes) in the Ryukyu Islands, Japan.  相似文献   

4.
A protocol using insect specimens or parts thereof allows for sequencing of sections of nuclear 28S rDNA. In the present note it is demonstrated that this protocol can readily be applied to strongly degraded DNA (ancient, fixed or contaminated). Primers that are specifically designed to discriminate against human DNA but also other non‐arthropod species are tested on a range of species covering all insect groups (59 insect species from all 33 orders). Additionally, the samples represent a selection of various, mostly DNA‐degrading, preservation methods, including the most common fixatives used for morphological investigations and for long‐term storage in collections. Successful amplification was possible for all tested samples including ca. 200 year‐old dried museum specimens as well as for over 4000 year‐old fossil insects embedded in copal. When the NCBI database contained information on the tested species an unambiguous taxonomic discrimination was possible. This approach is based on a standardized protocol that guarantees easy application. This note presents primer pairs for 28S rDNA that can be a useful tool for ancient DNA (aDNA) research.  相似文献   

5.
The reproductive biology of two species of endemic Southern Ocean octopods was investigated around the sub-Antarctic islands of South Georgia and Shag Rocks. The females of both the species produce few, large eggs. This appears to be governed by phylogenetic constraint. No evidence was found for ontogenetic migration or seasonality associated with gonad maturation. Based on oocyte length frequency distributions and observations of oocyte development within the ovary, it is possible that both species could have either a single or multiple-batch spawning strategy. Pareledone turqueti ovaries contained fewer larger oocytes than those of Adelieledone polymorpha, which may help to reduce competition for resources immediately after hatching.  相似文献   

6.
Mathematical expressions of variability or similarity based on data from pyrolysis-gas-liquid chromatograms were calculated for each combination among three strains of each of nine fasciculatePenicillium spp. The mean similarity for eight of these species clustered around 41 but the similarity forP. cyclopium was 58. Within each of the nine species, exceptP. urticae, at least one combination of strains had a similarity of 51 or greater. Similarities were also calculated for 576 possible combinations among 27 strains used in this study. These data indicate that certain strains of these nine penicillia may be more closely related to strains of other fasciculate species than they are to strains within their own species. This agrees with previous observations on variability and intergradation in the subsection Fasciculata.  相似文献   

7.
Infant sharing in the family colobidae emphasizingPygathrix   总被引:1,自引:1,他引:0  
Infant sharing of newborn has been observed in nature or captivity forColobus, Pygathrix, and several species ofPresbytis. It is suggested that this behavior may also occur inNasalis andProcolobus. Captive evidence demonstrates a need for field confirmation on birth intervals and further work on infant sharing as a possible survival mechanism.Juvenile males may participate more in infant sharing than is generally realized. Captive behavior inPygathrix indicates possible female dominance in infant sharing, for this species.  相似文献   

8.
Summary Fifteen species from three genera of the Casuarinaceae were inoculated with suspensions ofFrankia prepared from single nodule-lobes collected from different species and genera within the Casuarinaceae. Host-endophyte specificity was expressed mainly at the generic level. There was marked cross-inoculation within Casuarina and little nodulation ofCasuarina species from Allocasuarina sources with the exception of 3 sources ofFrankia fromA. torulosa which showed a high tendency to nodulateCasuarina species. Few sources from Casuarina nodulated species of Allocasuarina and while cross-inoculation within Allocasuarina was frequent it was less marked than within Casuarina. SomeFrankia inocula had wider host ranges than others, nodulating outside the genus or series of origin. It was not possible to determine if these apparent wider ranges in host spectra reflected genotypic differences betweenFrankia or were associated with the presence of more than oneFrankia strain in some inocula.  相似文献   

9.
A checklist of the Orchidaceae of Timor is presented, with emphasis on the eastern half of the island (East Timor), based on historical herbarium collections and recent botanical explorations. This list comprises 38 genera with 66 species, including 15 new genera and 32 new species records for this island. Moreover, four new species are described: Bulbophyllum sundaicum , Habenaria ankylocentron , Habenaria cauda‐porcelli , and Pterostylis timorensis . Of these, we consider the finding of a new species of Pterostylis to be especially noteworthy, because this species seems to be more closely related to certain Australian members of the genus than to the Malesian ones, suggesting earlier contacts of Timor with Australia. Four new synonyms are proposed: Calanthe veratrifolia var. timorensis J.J.Sm. (C. triplicata), Habenaria cornuta Span. (H. giriensis), H. grandis Benth. ex Ridl. (Peristylus goodyeroides), and H. mutica Span. (H. elongata). The best represented genus is Habenaria, with 13 species, followed by Dendrobium with four, and Bulbophyllum with three. Because of insufficient or sterile material, it was not possible to identify, or describe as new, 20 different taxa. The conservation status of the ten endemic species, plus six possible new undescribed species and two non‐endemic, but threatened, species, was assessed using the World Conservation Union (IUCN) criteria, and categories of threat were proposed. Seven endemic species are considered to be Critically Endangered and two Endangered. One of the nonendemic species is considered to be Critically Endangered, and the other Endangered. The survival of some of these species might be less insecure if an effective application of Regulation project N.2000/19 on protected areas (UNTAET/REG/2000/19) was implemented and maintained, because most of these species were collected in areas considered for protection under this Regulation. Further studies are required, however, in order to complete our knowledge of the diversity and population dynamics of this interesting part of Timor's biodiversity. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 157 , 197–215.  相似文献   

10.
Traditionally, control of European corn borer (Ostrinia nubilalis) Hübner has been achieved through the use of chemical insecticides. With increasing emphasis on reducing pesticide inputs in agricultural production, alternative management technologies are now being used including transgenic silage corn modified to express Cry1Ab protein toxins derived from Bacillus thuringiensis (Bt) Berliner. The Cry1Ab toxin is expressed by all plant cells and throughout the growing season. Furthermore, the toxins are exuded from corn plant roots into the rhizosphere, raising concerns over possible side-effects on non-target beneficial organisms in the same habitat. In addition, detrivores are exposed to crop residues containing the toxin when incorporated into the soil. The current 2-year study (2003, 2004) evaluated effects of two silage-corn varieties: Pioneer var. 38A25 (Bt-corn expressing the Cry1Ab toxin) and Pioneer var. 38A24 (parent isoline) on species diversity and evenness of carabid beetles and Collembola. Pitfall traps were used to collect surface-dwelling species on a bimonthly schedule from April to October. Soil cores were taken once a month from April to October to sample subterranean species, which were extracted using Berlese funnels. All individuals were recorded and identified where possible to species level for analysis in the Simpson’s D and Shannon–Wiener H’ diversity indices. Evenness was measured using Simpson’s E’, after which dominant species were analyzed in a multivariate ordination analysis. Results showed Bt-corn had no negative effects on any of the organisms analyzed. There was a significant year effect on the abundance of surface-dwelling Collembola and on species diversity of soil-dwelling Collembola. Our findings suggest that crop management practices and/or environmental conditions (e.g., heavy rainfall during the 2004 growing season) had the greatest impact on species diversity and evenness, rather than the crop itself (Bt or isoline).  相似文献   

11.
Sex allocation by the polyphagous solitary pupal parasitoid wasp Pimpla luctuosa Smith to a small host species, Galleria mellonella (L.), and a large host species, Mamestra brassicae L., was investigated to test whether female wasps responded to hosts of different sizes across different host species. In the experiments, both host species were presented to each test female wasp. Primary and secondary sex ratio experiments revealed that female wasps laid more female eggs in larger pupae of each host species, indicating that female wasps recognized size differences within host species. The wasp sex ratio (male ratio) from M. brassicae, however, was much higher than that expected on the basis of the sex ratio curve from different-sized G. mellonella. Larger hosts of each host species yielded larger wasps, indicating that the host size estimation by female wasps across different host species was incomplete or was not simple. These results suggested that P. luctuosa evaluated host size not only by physical measures such as dimension but also by other unknown measures. A possible explanation for the adaptiveness of different sex ratio responses by Pimpla luctuosa to different host species was discussed.  相似文献   

12.
13.
Abstract The species richness of the scuttle fly (Diptera: Phoridae) genus Megaselia was estimated by various non‐parametric estimators from EstimateS, Species Prediction And Diversity Estimation (SPADE) and Ws2m, based on material from a Swedish hemiboreal forest area recently affected by major wildfires, Tyresta National Park and Nature Reserve (TNPNR), south of Stockholm. A total of 21 249 individuals were collected in Malaise traps, of which males constituted 16 976 and females 4 273. The analysed dataset represents 37 samples containing 18 549 specimens sorted into 330 species (184 described, 146 are either undescribed or of unsettled taxonomic status). It was not possible to estimate the total species richness using all samples due to heterogeneity caused by inclusion of different communities and temporal incoherencies between samples within and between years. Even with material obtained from a sampling program that was not designed for species richness estimates, it was possible to obtain reliable results when sample heterogeneity was minimized. By dividing the data into community‐specific datasets – for bog, forest and wildfire – it was possible to obtain asymptotic curves for the smaller of the two wildfire datasets. A total estimate of 357–439 (95% CI) was attained by using the smaller wildfire dataset and adding the 85 unique species from the samples not included in the estimation analysis. TNPNR has one of the richest known scuttle fly communities in Europe, consisting of almost 50% of the currently named Megaselia species; 48 of these species are reported as new records for Sweden in this study.  相似文献   

14.
Summary Restriction fragment length polymorphisms (RFLPs) of nuclear DNAs have been used to explore the origin and evolution of the six cultivated Brassica species. Extensive RFLP variation was found at the species, subspecies and variety levels. Based on RFLP data from Brassica and related genera, a detailed phylogenetic tree was generated using the PAUP microcomputer program, which permits a quantitative analysis of the interrelationships among Brassica species. The results suggested that 1) B. nigra originated from one evolutionary pathway with Sinapis arvensis or a close relative as the likely progenitor, whereas B. campestris and B. oleracea came from another pathway with a possible common ancestor in wild B. oleracea or a closely related nine chromosome species; 2) the amphidiploid species B. napus and B. juncea have evolved through different combinations of the diploid morphotypes and thus polyphyletic origins may be a common mechanism for the natural occurrence of amphidiploids in Brassica; 3) the cytoplasm has played an important role in the nuclear genome evolution of amphidiploid species when the parental diploid species contain highly differentiated cytoplasms. A scheme for the origins of diploid and amphidiploid species is depicted based on evidence gathered from nuclear RFLP analysis, cpDNA RFLP analysis, cytogenetic studies and classical taxonomy.  相似文献   

15.
Abstract. Common reed (Phragmites australis Trin.) has spread in fen meadows on the Swiss Plateau during the last decades. An increased dominance of this tall grass may reduce the plant species richness and displace rare or endangered species because of the additional shade. To investigate whether this has actually happened and whether shading by Phragmites was likely to be responsible for the reduction, the plant species composition was surveyed in 241 plots (4 m2) with differing above-ground biomass of Phragmites (ABP). Species richness and the occurrence of characteristic fen species were negatively related to site productivity (total above-ground biomass), but correlations with ABP were generally weaker. The main change associated with increasing ABP within species-rich fens (alliances Molinion and Caricion davallianae) was an increase of species characteristic of the more species-poor alliance Filipendulion. Thus, Phragmites did apparently not play a disproportionate role in the reduction of species richness in the plant communities studied. Selective clipping experiments and light measurements also indicated that shading by Phragmites does not have a strong effect upon the performance of other species in the community, at least in the short term. The reason appeared to lie in the later seasonal growth of Phragmites compared with the other species. These results suggest that the direct impact of shading by Phragmites on the species richness of fen meadows is probably lower than has been assumed. However, possible long-term or indirect effects still need to be investigated.  相似文献   

16.
Deep-water habitats are among the least studied but most vulnerable environments. By-catch data from deep-water fisheries in Latin America are limited, and detailed reports on associated molluscs are scarce. This study provides information on deep-water shelled molluscs collected between 2010 and 2011 by commercial shrimp trawling fisheries along the Pacific coast of Costa Rica at depths from 112 to 271?m. Twenty-six species were identified, 23 gastropods and three bivalves. Our data extend the depth range of 14 species, and Homalopoma cf. grippii is reported for the first time for Costa Rica. The most common species were the gastropods Fusinus spectrum, Polystira nobilis and Solenosteira gatesi. Only one species (Sinum debile) was captured below 250?m. The catch of molluscs per unit effort was influenced by depth, but not by seasonality or geographic area. It is speculated that these long-lasting bottom-trawling activities have caused negative effects on species diversity and mollusc biomass. Nevertheless, a monitoring program is recommended to assess possible impacts of this type of fishery on mollusc diversity and biomass.  相似文献   

17.
Understanding the evolutionary potential of morphological evolution is still a major problem in evolutionary biology. In this study, we tried to quantify the amount of variation of different traits among species of a Drosophila clade reared under standard conditions. Nineteen different traits have been measured on nine species of the same clade, the Neotropical saltans group of Drosophila. Measured traits can be distributed into five categories: size‐traits (wing and thorax), shape indices (ratios among the size traits), number of sternopleural bristles on the thorax, number of abdominal bristles on successive sternites, and dorsal pigmentation of abdomen. All species are of medium size with a generally dark pigmentation. A remarkable feature is the presence of numerous bristles on the 6th sternite of the males, while this segment is bare in other Drosophila species. A multivariate analysis revealed that it was possible to discriminate all the investigated species by using the complete set of measured traits. For each trait, phenotypic variability was investigated at the within‐ and between‐species levels. As a rule, the interspecific coefficient of variation (CV) was much greater than the within species CV, and it is proposed to call it realized evolvability. All possible correlations were calculated between traits across species, providing many unexpected results. Size traits were highly correlated among them, but not correlated with shape indices. Abdominal traits (bristles and pigmentation) were correlated, but often in opposite directions, with thoracic shape indices. Tergite pigmentation was negatively correlated with bristle number on sternite. For the moment, most of the correlations cannot be explained by developmental processes or parallel selective pressures. Nonetheless, mapping the evolution of the two characters on a molecular phylogeny of the studied species revealed two opposite phylogenetic trends for abdominal pigmentation and setation, respectively. Our data suggest a need for similar studies in other well‐defined Drosophila clades.  相似文献   

18.
Plant chemistry can strongly influence interactions between herbivores and their natural enemies, either by providing volatile compounds that serve as foraging cues for parasitoids or predators, or by affecting the quality of herbivores as hosts or prey. Through these effects plants may influence parasitoid population genetic structure. We tested for a possible specialization on specific crop plants in Chelonus insularis and Campoletis sonorensis, two primary parasitoids of the fall armyworm, Spodoptera frugiperda. Throughout Mexico, S. frugiperda larvae were collected from their main host plants, maize and sorghum and parasitoids that emerged from the larvae were used for subsequent comparison by molecular analysis. Genetic variation at eight and 11 microsatellites were respectively assayed for C. insularis and C. sonorensis to examine isolation by distance, host plant and regional effects. Kinship analyses were also performed to assess female migration among host‐plants. The analyses showed considerable within population variation and revealed a significant regional effect. No effect of host plant on population structure of either of the two parasitoid species was found. Isolation by distance was observed at the individual level, but not at the population level. Kinship analyses revealed significantly more genetically related—or kin—individuals on the same plant species than on different plant species, suggesting that locally, mothers preferentially stay on the same plant species. Although the standard population genetics parameters showed no effect of plant species on population structure, the kinship analyses revealed that mothers exhibit plant species fidelity, which may speed up divergence if adaptation were to occur.  相似文献   

19.
Many species of microscopic invertebrates, such as tardigrades or rotifers, have been traditionally regarded as cosmopolitan. This conviction was based on classical taxonomic observations of very similar phenotypes across the globe and hypothetical abilities of micrometazoans for large-scale dispersal with air and water currents. However, several recent studies showed that micrometazoan species may have restricted geographic ranges, suggesting that microscopic size is not the only determinant of dispersal. Here, we describe the first Australasian record of Echiniscus testudo, a heterotardigrade originally described from the Holarctic. Morphological and genetic analyses gave congruent conclusions and confirmed that European and New Zealand populations represent a single species. Importantly, however, without broader sampling in primeval localities, it is not possible to test whether the New Zealand record of E. testudo is a result of natural dispersal or whether the species was brought to Australasia by humans.  相似文献   

20.
The duplex coefficient of specific correlation was applied for the first time for the estimation of possible interaction between water and terrestrial hyphomycetes (Alternaria sp. and Fusarium sp.) and oomycete Achlya sp. under microcosm conditions. Values of the either direct or indirect coefficient for correlation between water and terrestrial hyphomycetes and oomycete Achlya sp. were predominantly negative. Values of the coefficient for correlation between more frequent water hyphomycete species were more often positive or near 0. Rare water hyphomycete species had usually more or less distinct negative correlation with other water hyphomycete species.  相似文献   

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