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101.
Concentrations of heavy metals (zinc, copper and lead) were manipulated experimentally to test the hypotheses about effects on intertidal, soft-sediment assemblages of animals in two sand-flats in Port Hacking, Australia. Hypotheses about changes in the structure and composition of whole assemblages and changes in mean abundance and variability of individual taxa were tested. Specific hypotheses were derived a priori from repeated observations of assemblages in urban and non-urban areas of Port Hacking.After manipulation, concentrations of metals were similar to those in sediments near urban areas. Nevertheless, responses of assemblages to the increased concentrations of metals were weak. Polychaetes, spionids and amphipods responded to experimental treatments. Changes were, however, not consistent among times and places and generally not in agreement with what had been predicted. Significant spatial and temporal variability were detected for all variables investigated. Increased concentrations of metals did not affect variability or overall structure of assemblages. Thus, there was little evidence that increased concentrations of metals caused benthic assemblages in pristine areas to become more similar to those in areas contaminated by human activities.Several potential explanations for the discrepancy between previously observed correlative patterns and the results presented here are discussed. These include a critical assessment of different aspects of the experimental study, such as lack of statistical power, insufficient basis for prediction, artefacts due to experimental procedures and issues to do with the difference between evidence based on correlation and manipulation. Explicit comparisons showed that there were significant effects of physical disturbance due to repeated sampling and that assemblages of animals at the start of the experiment were different from those previously observed in uncontaminated areas. These observations were surprising and made interpretation more difficult. Nevertheless, it is possible that the metals investigated really contribute only marginally to previously observed differences between urban and non-urban areas. Repeated comparisons between observations of patterns and manipulative experiments like these can only improve the basis for prediction and the power of current mechanistic models. 相似文献
102.
Comparative efficiency of clove oil and rotenone for sampling tropical reef fish assemblages 总被引:2,自引:0,他引:2
A quantitative examination of the reef fish assemblage at Orpheus Island, Great Barrier Reef, contrasting clove oil and rotenone, sampled 365 individuals of 47 species with clove oil v. 536 individuals of 53 species with rotenone. Number of species and individuals were not found to differ significantly between the two techniques, largely due to variation among samples. Neopomacentrus bankieri (Pomacentridae) and Eviota queenslandica (Gobiidae) were the most dominant in the samples using either technique. Although the samples appeared to be comparable, only 31 species (45%) in eight families were common to both techniques. Fishes often recovered before collection when using clove oil and were not driven out of the reef during induction to anaesthesia. Although the samples collected with clove oil approximate the results obtained using rotenone, enclosed rotenone stations are the preferred method for providing relatively complete quantitative samples. 相似文献
103.
The tropical butterfly Bicyclus anynana shows phenotypic plasticity in its ventral wing pattern as an adaptive response to wet‐dry seasonality. Wet season form individuals have large eyespots, whereas individuals of the dry season generation have small eyespots. In the laboratory these forms can be obtained by rearing larvae at high and low temperatures, respectively. To study the extent to which the shape of the nearly linear reaction norms for eyespot size can be changed we applied four generations of sib selection by rearing full‐sib families across three temperatures. In addition, we measured ecdysteroid titres shortly after pupation in the final generation. Although phenotypic variation in shape was present initially, the experiment yielded lines with reaction norms with similar shapes but different elevations. High, positive genetic correlation across temperatures can explain this lack of response. Differences in ecdysteroid titres did not readily relate to differences in eyespot size. 相似文献
104.
Abstract. Using the unusually well-documented butterfly fauna of Davis, Yolo County, California, it is shown that the mainly native species commonly observed in gardens breed mostly or entirely on alien plants, especially naturalized weeds. Over 40% of the fauna has no known native hosts in the urban–suburban environment. Were certain alien weeds to be eradicated or their abundance greatly reduced, the urban-suburban butterfly fauna would disappear. This might be regarded as an unfortunate, and perhaps intolerable, side-effect of such programs. 相似文献
105.
Abstract. A study to assess the influence of abiotic (climatic conditions) and biotic factors (food resources, habitat preference and human activity) on endemism patterns of dung beetles in the Mediterranean region was conducted in the Iberian Peninsula and the Balearic Islands. The Thermicity Index (It), the Mediterraneity Index (Im3) and the Aridity Index (Ia) were used to assess the influence of abiotic factors. Relative rabbit density (DR), the proportion of landscape used historically for grazing by sheep and goats and the nature of the food resource were used to assess the influence of biotic factors. Relative endemism (EN) of dung beetle assemblages was positively and significantly related with all of the factors considered. However, the Aridity and Mediterraneity Indices are the best predictors of EN. The predicted endemism (EN = 0.017 Ia + 0.004 Im3 + 0.422) was highly positively and significantly related with the observed endemism. Dung beetle assemblages with the highest relative endemism were observed in the south-eastern part of the Iberian Peninsula. This distribution corresponded to the highest Aridity and Mediterraneity. In contrast, dung beetle assemblages with lower endemism were located in more humid and temperate areas. Assemblages of dung beetles with the highest endemism comprise many species adapted to aridity and the exploitation of dry dung pellets. Conservation of traditional grazing activity by pellet-dropping sheep and goats might benefit the maintenance of dung beetle biodiversity in Mediterranean ecosystems. 相似文献
106.
The relationship between butterfly diversity and both habitat and landscape variables was studied in two areas of southern Sweden. The habitat quality of the grasslands was similar in the two study areas but the landscape pattern differed in grain size and amount of grassland and forest. Using a transect survey method, a total of 3341 butterflies were observed and 30 taxa identified. We found that both habitat and landscape variables influenced the butterfly diversity of the investigated grasslands. Species composition differed markedly between the two study areas. A study area with a fine-grained landscape pattern, a high cover of semi-natural grassland and many forest edges had twice as many butterfly species but half the number of individuals compared with a coarser-grained study area with larger grasslands widely spread in a matrix of arable fields. The results of our study indicate that both habitat quality and landscape pattern have to be considered when developing conservation strategies for grassland butterflies. 相似文献
107.
黔东早—中寒武世凯里组疑源类组合及其界线意义 总被引:13,自引:0,他引:13
通过对台江八郎和丹寨两条剖面凯里组中疑源类化石的分析,研究,台江剖面产疑源类化石有17属35各(12未定种),其中以Leiosphaeridia,Synsphareidium,Cymatiosphaera,Pterospermella最为丰富,可划分为3个组合,即Cymatiosphaera cf.cristata-Fimbriaglomerella memebrancea组合,Cristallinium-Micrhystridium-Pterospermella组合和Dictyotidium-Granomarginata组合,丹寨平寨剖面凯里组所产疑源类化石有:13属21种(5未定种),同样划分为3个组合,即Leiosphaeridia-Tasmanites组合,Retisphaeridium-Micrhystridium tentatium组合和Baltisphaeridium-Bubomorpha hunjiangensis组合,本文对两条剖面中的凝源类化石的组成,相对含量做了详细的统计,发现在八郎剖面9-2层和平寨剖面3层疑源类的丰度,分异度开始发生明显的变化,表现由早寒武世向中寒武世疑源类组合面貌的转变,这一疑源类转变层位正好是与三叶虫划分的中,下寒武统界线的层位位置相一致,这充分表明疑源类化石可作为划分中,下寒武统的极有价值的微体生物化石证据。 相似文献
108.
Dependence on wild seed sources is often impractical for large‐scale habitat restoration programs. Reliance on commercial seed supplies of unknown provenance and fitness is thereby warranted. Little consideration has been given, however, to how the large volumes of seed required should be sourced. We evaluated commercial and locally collected seed sources for potential use in a New York State‐based, landscape‐scale program for restoring blue lupine Lupinus perennis. Through analysis of microsatellite markers we determined that “native” lupine designations by some commercial suppliers were in fact interspecific hybrids and therefore unreliable; at least two commercial sources, however, were genetically as close to native New York populations as native New York populations were to one other. Common garden experiments revealed that seed source influenced first‐year overwintering survival and subsequent height growth of surviving plants; seed sources more closely related genetically to native New York populations survived better and produced more stems per individual in the field in the area targeted for restoration. We conclude that (1) commercial suppliers often but not always offer reliably characterized seed sources of sufficient genetic similarity to native populations to warrant their use in restoration projects and (2) genetic affinity of potential seed stock to native populations is positively related to its fitness in the environment targeted for restoration. 相似文献
109.
In the framework of the palaeogeographical reconstruction of the Western Taurus during Jurassic, the study of northern and eastern boundary of the Taurids started. Detailed facies analysis evidenced the position of the Barla Dag ramp between two elevated areas: the southern rimmed shelf extension of the platform system and the northern neritic-beach-land plain. In the basal biostratigraphical and ecological characteristics of the Balcikhisar volcano-sedimentary sequence, correlated with the Fele outcrop, one genus and three new species of foraminifers have been found: Sievoides kocyigiti n. gen., n. sp. and Mesoendothyra altineriana n. sp. from neritic environment, and Kurnubia feleensis n. sp. from rimmed shelf lagoon. Both carbonate sedimentary deposits are intercalated with spilitic-basalt pillow lava flows. The age of the new three species is Kimmeridgian, controlled by some foraminifer golden hooks. 相似文献
110.
Philip E. Howse 《Biological journal of the Linnean Society. Linnean Society of London》2013,109(1):203-214
The hypothesis of satyric mimicry postulates that the colour patterns of an animal may make its identity ambiguous, and this ambiguity interferes with the process of perception in vertebrate predators for a sufficient time to allow the potential prey to take evasive action. It has now been found that eyespots and other designs on the wings of many insect species are often coupled with other wing patterns and designs. These composite images often closely resemble heads and bodies of vertebrates (including birds and reptiles) and of various invertebrates. Such images can be perceived in living insects, although only rarely in set specimens because of displacement of the components. Visual processing by non‐mammalian vertebrates generally involves attention to detail, suggesting that, at least initially, and unlike humans, they perceive embedded images on insect wings and bodies and ignore the whole or Gestalt. They are therefore likely to be confused by the ambiguity of the potential prey. It can be calculated that a delay of the order of only tenths of a second in the attack on a stationary insect by a predator could result in failure of capture. It is proposed in the present review that the concept of satyric mimicry be extended to include complex imagery of other organisms. Such iconic images, which often represent toxic or dangerous animals, are particularly common amongst saturniid moths and nymphalid and danaid butterflies (including the Monarch butterfly, Danaus plexippus). © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109 , 203–214. 相似文献