首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 734 毫秒
1.
《Journal of Natural History》2012,46(37-38):2329-2356
A lineal “island” theory is proposed to account for the dispersal of marine/estuarine, supralittoral talitrid populations, both to and from isolated shore “islands” on continental and true oceanic islands. Evolution may occur following dispersal to shores that are contiguous with ecologically open habitats, inclusive of sub-tropical forest litter and caves. Specific hypotheses of the lineal “island” theory are therefore: the conventional wrack hypothesis 1 – direct from marine supralittoral wrack to subtropical forest litter; the driftwood hypothesis 2(a) – direct from marine supralittoral driftwood to subtropical forest litter; the driftwood hypothesis 2(b) – direct from the marine supralittoral driftwood to caves opening on a marine supralittoral; and the driftwood hypothesis 2(c) – direct from the marine supralittoral driftwood via caves to subtropical forest litter. Circumstantial evidence supporting each hypothesis is presented using the ecology and distribution data of the talitrid fauna of the northeast Atlantic islands, north of 25°N and south of 40°N, including the Canaries, Madeira and the Azores archipelagos. The currently known talitrid fauna of all these islands includes 15 species: seven endemic, subtropical landhoppers, two synanthropically introduced landhoppers, three wrack generalists, one sand-burrowing specialist, one specialist cavehopper, and one specialist driftwood hopper. Based on distributional data from the northeastern Atantic islands, specialist driftwood hoppers have a long distance dispersal capability, which makes them potential colonizers of distant oceanic islands. Talitrids provide an excellent model of dispersal and speciation, whose evolutionary pathways can be solved by modern genetic methods.  相似文献   

2.
We report 4 incidents of large (hundreds to hundreds of thousands of individuals) mixed-species flights of predatory and scavenging aquatic Heteroptera and Coleoptera. The events occurred on normal (mostly clear, calm) autumn 2005 and spring 2006 late afternoons near Flagstaff, Arizona. Flight days were either near the full moon or in advanced waning lunar periods. At least 18 species were involved in the flights, with as many as 16 species (7 species of Heteroptera in 3 families, 9 species of Coleoptera in 2 families) in a single flight. Heteroptera (especially from the family Corixidae) were 2–4 orders of magnitude more numerous than Coleoptera. The diasporas plummeted, with much direct mortality, onto green metal roofs, and the largest event lasted more than 2 hours. Even after 2 days, uninjured individuals failed to resume their flights. The literature suggests that such flights occur for autumn movement to winter habitats or for location of springtime habitats for reproduction. The relative proportions of species in flocks were similar neither to the relative proportions in the region nor to those in nearby livestock watering tanks, indicating that the flights consisted of nonrandom assemblages of species. These events are rare or unique observations of coordinated movement of mixed predatory and scavenging invertebrate species.  相似文献   

3.
In desert environments seeds are often heterogeneously distributed in small patches that vary in number of seed species and in seed density. Because seed harvest by rodents is often density dependent (a larger proportion of seeds is removed from high-density seed patches than from low-density patches), the proportion of residual or post-harvest seeds should be greater in low-density patches. In addition, seed preference can affect harvest. We tested whether the residual proportion of a highly preferred seed (Indian ricegrass, Oryzopsis hymenoides ) was less when in a seed patch with a 2nd species (mixed-species patch) than when in a monospecific seed patch. We predicted that the increased overall seed density due to the presence of 2 species in a patch would result in a lower residual proportion of ricegrass seeds in the mixed-species seed patches than in the monospecific patches. As predicted, the residual proportions of Indian ricegrass seeds were less each time ricegrass was paired with one of 6 other species in mixed-species patches. Similarly, the residual proportion of each of those 6 species was less when paired with ricegrass than when in a monospecific patch. We speculate on the potential implications of these results for the population dynamics of plant species and the physical structure of plant communities.  相似文献   

4.
《Journal of Natural History》2012,46(41-42):2577-2604
The influence of temporal variation in the host specificity of invertebrates to estimates of biodiversity is rarely considered. While patterns at large spatial scales have stimulated much attention, such comparisons are constrained for southern-hemisphere biomes because the patterning of invertebrates on plants is largely unknown. Here, we analyse variation of plant-dwelling Hemiptera from 15 understorey plant species over 18 months in the south-west Australian biodiversity hotspot. Analyses showed significant interactions in species composition between sampling period and plant species. Fauna that were “effectively specialized” (host-specificity index) to plants changed with season, although this was also related to the number of singletons and overall species richness. Sampling from a single season also overestimated the degree of host specificity by 52% and underestimated the perception of species richness when an outbreak of a particular herbivore occurred. High host-specificity values (12.7 hemipteran species per plant) support the case for high estimates of global arthropod richness.  相似文献   

5.
《Journal of Natural History》2012,46(27-28):1893-1906
This investigation focuses on the diversity and taxonomy of species of Microporella found north of the Arctic Circle. Firstly, however, a neotype is chosen for the Mediterranean type species M. ciliata (Pallas) in order to stabilize the taxonomy of this “pseudocosmopolitan” species, which has been recorded in the past from the Arctic. Study of type and other material using scanning electron microscopy shows that only two Arctic species of Microporella can be recognized, M. arctica Norman and M. klugei sp. nov. The first of these is characterized by a large ascopore divided by thin radial septa and situated close to the proximal rim of the orifice. Microporella klugei sp. nov. differs in having a smaller, undivided ascopore situated in a more proximal position on the frontal shield. Both Arctic species are notable among Microporella species for having a high proportion of autozooids without associated avicularia.  相似文献   

6.
A new species belonging to the genus Ooencyrtus Ashmead is described. Ooencyrtus marcelloi sp. nov. has been reared from eggs of Heliconiini (Lepidoptera: Nymphalidae, Heliconiinae) collected in Panama on Passiflora spp. The new species is compared with its closest Ooencyrtus species, i.e. O. caligo Noyes, O. neustriae Mercet, O. flavipes (Timberlake), O. camerounensis (Risbec), O. endymion Huang and Noyes and Ooencyrtus sp. “undet. C.” (from India). This represents the second record of Ooencyrtus from Heliconinae and the first record of this genus from Panama.  相似文献   

7.
《Journal of Natural History》2012,46(5-6):301-306
In 2007, a 3-year survey was started in northeastern Italy to assess the influence of agricultural management on parasitoid composition and parasitism rates of parasitoids attacking larvae and pupae of Syrphidae (Diptera). Two types of management were considered – intensive (including wheat and maize monoculture with very low or null vegetation diversity) and extensive (with different types of habitats, characterized by a higher vegetation complexity). In habitats simplified by intensive agriculture, and particularly in maize fields, parasitism rates of syrphid larvae were higher than recorded in more diversified habitats. A substantial difference in the composition of the parasitoid complex was also found. In extensive and wheat sites, Diplazontinae (Braconidae), highly specialized to Syrphidae, were the dominant parasitoids, whereas in maize fields Pachyneuron (Pteromalidae) species, known as generalists, accounted for more than 80% of total parasitoids. In the habitats where Pachyneuron spp. were dominant, parasitism rates were very high. Conversely, in habitats where Diplazontinae were more abundant, the parasitism rates were very low. The higher rate of parasitism of syrphid larvae and pupae recorded in intensive monocultures could have a large impact on the development and control of aphid populations in such crops.  相似文献   

8.
The Mediterranean Sea is known as a biodiversity hot spot, with 16,848 species reported. Biodiversity is higher in coastal areas and decreases with depth. However, knowledge about the southwestern sector remains scarce. For the last three decades, sampling of soft-bottom communities along the 1180 km of the shallow Algerian coast (0–136 m) has recorded 1642 macrobenthic species. There is a decreasing west–east species-richness gradient, especially for the total species richness and the amphipods. In addition, quantitative sampling in Bou Ismail Bay in summer 1988 (98 sampling sites for a total of 841 species) shows that diversity indices (i.e. species richness, >100 species for 0.2 m?2; Shannon diversity, >6.0; and ES50, >34) are among the highest for similar sand and muddy-fine sand communities in the Mediterranean Sea and the northeastern Atlantic Ocean. Bou Ismail Bay appears to have the highest species richness among Algerian bays, probably because of its variety of benthic habitats and the absence of significant pollution in this area. Monitoring must be undertaken to survey this high biodiversity, and a national strategy should be proposed to preserve high diversity zones.  相似文献   

9.
This study investigated local distribution and foraging behavior of the spotted bat ( Euderma maculatum ) in Dinosaur National Monument, Colorado-Utah, by monitoring audible echolocation calls. The occurrence of this species was verified in a variety of habitat types in canyon bottoms and other relatively low elevation sites, indicating that the animals were widely distributed and locally common in the area. Foraging spotted bats concentrated flight activity in the open-air space above meadows occasionally exploited near-canopy habitat (within 8 m of foliage). Bats began to forage shortly after dark, and activity levels were relatively constant throughout the night. Foraging spotted bats attacked airborne prey every 2.15 min on average. Consistent with published observations, spotted bats maintained exclusive foraging areas. Distinct vocalizations indicating agonistic encounters occurred when a bat encroached on the foraging area of a conspecific.  相似文献   

10.
Behavior of migrant birds in relation to temperature was studied and compared to that of resident species in the northern Mojave Desert. Migrants reduced foraging intensity above 30 C, but resident species showed no striking decrease in intensity of foraging at temperatures up to 35 C. Migrant species shifted activities to shaded microhabitats at temperatures between 20 and 30 C; the resident Verdin showed a similar shift at 35 C. Most migrants decreased the amount of time spent foraging at temperatures above 30; Verdins showed a similar but stronger response to temperatures about 30 C. Significant reductions in the use of hovering and hawking maneuvers were found among migrants at temperatures above 30 C. Migrants showed similar types of behavioral adjustments to temperatures as did resident desert species, but they responded earlier in the daily temperature cycle. Desert birds appear to correlate their daily activity strongly with temperature, but nondesert species may respond either to temperature or time of day.  相似文献   

11.
The revision of the saproxylic hoverflies collected in Serbia from 1950 to 2010 has revealed a total of 56 species, of which Sphiximorpha subsessilis (Illiger in Rossi) is new to the Balkan Peninsula and Arctophila superbiens (Muller), Blera fallax (Linnaeus), Brachyopa panzeri Goffe, Brachyopa testacea (Fallén), Brachyopa vittata Zetterstedt and Chalcosyrphus piger (Fabricius) are new to Serbia. According to “Syrph the Net, the database of European Syrphidae”, 16 of the 56 species are threatened with extinction in Europe, while 6 species are “strictly protected” and 13 are “protected” under Serbian legislation. Distribution maps for each species, as well as new data on adult habitats, are provided. The conservation status of the saproxylic hoverflies of Serbia is discussed. The present study attempts to provide a basis for the conservation of the saproxylic hoverflies of this Balkan country.  相似文献   

12.
13.
《Journal of Natural History》2012,46(41-44):2741-2755
A new species of the tardigrade genus Macrobiotus is described. The species, designated M. ciprianoi n. sp., was isolated from a mixture of Provence broom leaf litter and mosses, and from rock mosses collected in the Sierra de Guadarrama, Madrid (Spain). Given that Macrobiotus ciprianoi n. sp. shares several characters to members of the “tenuis group”, we assessed the taxonomic homogeneity of the group. The new species differs from those of the “tenuis group” according to a unique set of characters related with claw shape, features of the buccal‐pharyngeal apparatus, and egg morphology. Our analysis of holotypes and/or paratypes of “tenuis group” species and other Macrobiotus species with similar characters (M. bondavallii and M. caelicola) reflects the heterogeneity of this group of species as currently described.  相似文献   

14.
《Journal of Natural History》2012,46(19):1597-1625
Additional specimens belonging to the rare crangonid genus Prionocrangon Wood‐Mason and Alcock, collected from recent deep‐sea expeditions in the West Pacific enable a revision of this poorly known genus. The four previously described species are all valid. The type species P. ommatosteres Wood‐Mason and Alcock, , originally known only from the Andaman Sea, is considered to be also distributed in the Philippines and Indonesia. However, the material previously assigned to “P. ommatosteres” by de Man () and Chace () from Indonesia and the Philippines actually represents a new species, P. demani sp. nov., close to P. pectinata Faxon, . Prionocrangon pectinata and P. curvicaulis Yaldwyn, are still only known by their types. The distribution of P. dofleini Balss, is now extended from Japan to Taiwan. Two more new species are recognized. Prionocrangon formosa sp. nov. from Taiwan is closely related to P. curvicaulis while P. paucispina sp. nov. from Taiwan and New Caledonia is unique in having very few dorsal carapace spines. The genus Prionocrangon is newly diagnosed and a key to the species is provided. Nevertheless, a damaged specimen from the Sulu Sea could not be satisfactorily assigned to any of the above seven species, suggesting that this genus may have even higher diversity.  相似文献   

15.
In this report we analyze patterns of size-assortative mating in an insect genus by (1) describing the consistency and strength of assortative mating among populations of a species and among species of a genus, and (2) determining the role of sampling artifacts in generating this nonrandom pattern of mating. Our data consist of 18 samples of soldier beetles (8 species of the genus Chauliognathus ) from 17 sites within the southwestern United States. Of the 18 samples, just 6 exhibited significant correlations between elytron lengths of mating pairs. We show how these and other significant correlations are generated by 3 kinds of sampling artifacts: mixed-species samples, mixed-population samples, and mixed-microsite samples.  相似文献   

16.
A list of species of the family Caliscelidae Amyot et Serville known from India with data on distribution and sources for identification and a key to genera are given. The genus Bolbonaso Emeljanov, 2007 is revised. A new species, Bolbonaso chandri sp. nov., is described from Eastern India (Assam and Meghalaya States). Bolbonaso tapirifacies (Parshad, 1981) is redescribed and recorded for the first time from Southern India (Karnataka State). The lectotype is designated for Chirodisca eximia (Stål, 1859) which is recorded for the first time from Pakistan. New faunistic data in Nepal are listed for Delhina eurybrachydoides Distant, 1912.  相似文献   

17.
《Journal of Natural History》2012,46(35-36):2209-2226
Catenicella paradoxa sp. nov. is described from Mediterranean shallow bottoms. Colonies are small, rooted, erect and articulated, each segment either sterile unizooidal or bizooidal, or fertile bizooidal. Basal parts consist of an “articulated basal complex”, sometimes related to thick encrusting tubes, invariably followed by morphologically ordinary zooids belonging to each type of segment. The hypotheses of small separate colonies or subcolonies from a network of encrusting tubes are discussed, but relationships with the substratum remain unclear. The species represents the first known Mediterranean catenicellid, a family taxon with a warm, mostly Australasian present-day distribution. Nevertheless, catenicellids and Catenicella species have a long history in the European area from the Middle Eocene to the Early Pleistocene, with at least four different species. In this context, the meaning of C. paradoxa sp. nov. is discussed, bearing in mind problems of species spreading in relation to global warming and human activities.  相似文献   

18.
《Journal of Natural History》2012,46(14):1765-1777
Taxonomic families of insectivorous lizards are usually characterized by one of two distinct foraging modes, namely ambush ‘sit-and-wait’ or active ‘widely foraging’. In the Gekkonomorpha the situation has been unclear and in dispute, and among these, that in the Sphaerodactylini is almost unreported. We, therefore, examined the foraging mode of three sphaerodactylin species on Trinidad and Tobago, in May—June 2000 (totalling 72 individuals, observations averaging 23.6 min/individual). In terms of species averages, Gonatodes vittatus, G. humeralis and G. ocellatus all moved for only 1.6–3.55% of observation time (PTM, percent time moving), and switched from sitting to locomoting only 0.18–0.36 times per minute (MPM, moves per minute). The genus thus is a strict sit-and-wait forager. In G. vittatus, the foraging mode was unaffected by sex or habitat structure. In all three species, foraging mode was unaffected by the time of day or air temperature. In G. humeralis, foraging activity (PTM or MPM) correlated with light intensity in the forest within a population (at least MPM) and among populations (at least PTM). Among the three species, too, foraging activity (PTM and MPM) ranked with light intensity during sampling. In all three species, the geckos perched for 68–76% of the time (at any height) with the head pointing down, apparently so as to see better. In conclusion, the three species are strict sit-and-wait' visual hunters that are dependent on light.  相似文献   

19.
《Journal of Natural History》2012,46(39):3453-3470
This work is a study of the communities of oribatid mites in steppic areas of Burgos Province, central northern Spain, in relation to different habitat types belonging to natural or disturbed ecosystems. The primary objective was to find the relationship between anthropogenic use of land and several diversity indices. Parameters such as abundance, species richness, real diversity (H′) and equitability (J′) of the mite communities were calculated in 20 soil plots, sampled in spring and autumn 2000, belonging to the predominant habitat types of this area: (1) cultivated lands, (2) abandoned crop lands, (3) grasslands/pastures, and (4) natural oak forests or a pine plantation. The most widespread species in the area as well as the most abundant taxa overall are documented, together with the faunistic checklist of oribatid mites identified in the study. The results show a general decline in the composition of the oribatid community, in terms of species diversity and abundance, from non‐disturbed soils to cultivated lands. The number of species (richness) was usually higher in forest soils than in disturbed ecosystems, in which the most degraded soils showed the lowest number of species. The community analysis shows the differences due to habitat type and ubiquitous bioindicator species.  相似文献   

20.
Vegetation characteristics of 15 sagebrush community types identified on the Humboldt National Forest, northeastern Nevada, are described. A total of 218 plant species were found over the 372 relatively undisturbed rangeland communities sampled. The dominant plant families encountered were the Asteraceae (45 taxa), Poaceae (32 taxa), Scrophulariaceae (14 taxa), and the Fabaceae (12 taxa). Average annual dry weight production of the community types ranged from about 400 kg/ha/yr on types with Artemisia nova as the dominant sagebrush species to 1,200 kg/ha/yr on some A. tridentata ssp. vaseyana community types. A general increase in species richness and vegetation plus litter ground cover was observed within community types as the dominant sagebrush species changed from A. nova to A. arbuscula to A. longiloba to A. tridentata spp. tridentata to A. tridentata ssp. vaseyana . Major differences in plant species production and constancy exist between the sagebrush community types studied.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号