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1.
The functioning of the vertebrate eye depends on its absolute size, which is presumably adapted to specific needs. Eye size variation in lidless and spectacled colubrid snakes was investigated, including 839 specimens belonging to 49 genera, 66 species and subspecies. Variations of adult eye diameters (EDs) in both absolute and relative terms between species were correlated with parameters reflecting behavioral ecology. In absolute terms, eye of arboreal species was larger than in terrestrial and semiaquatic species. For diurnal species, EDs of terrestrial species do not differ from semiaquatic species; for nocturnal species the ED of terrestrial species is larger than fossorial species but not different from semiaquatic species. In relative terms, ED did not differ significantly by habitat for diurnal species. Although the ED of terrestrial species is larger than fossorial species there were no differences for nocturnal species between semiaquatic and fossorial snakes. In contrast to other vertebrates studied to date, colubrid EDs in absolute and relative terms are larger in diurnal than in nocturnal species. These observations suggest that among colubrid snakes, eye size variation reflects adaptation to specific habitats, foraging strategies and daily activities, independently of phylogeny. J. Morphol. 2012. © 2012 Wiley Periodicals, Inc. 相似文献
2.
The probability that protected areas will deliver their potential for maintaining or enhancing biodiversity is likely to be
maximised if they are appropriately and effectively managed. As a result, governments and conservation agencies are devoting
much attention to the management of protected areas. In the U.K., the demand for performance accountability has resulted in
Public Service Agreements (PSA) that set out targets for government departments to deliver results in return for investments
being made. One such target for England is to ensure that all nationally important wildlife sites are in favourable condition
by 2010. Here, we tested the hypothesis, of potential strategic importance, that the ecological condition of these sites is
predictable from relationships with a range of physical, environmental and demographic variables. We used binary logistic
regression to investigate these relationships, using the results of English Nature’s 1997–2003 condition assessment exercise.
Generally, sites in unfavourable condition tend to be larger in area, located at higher elevations, but with higher human
population density and are more spatially isolated from units of the same habitat. However, despite the range of different
parameters included in our models, the extent to which the condition of any given site could be predicted was low. Our results
have implications for the delivery of PSA targets, funding allocation, and the location of new protected areas. 相似文献
3.
4.
5.
The Importance of Hydrodynamics for Protected and Endangered Biodiversity of Lowland Rivers 总被引:3,自引:3,他引:0
R. J. W. de Nooij W. C. E. P. Verberk H. J. R. Lenders R. S. E. W. Leuven P. H. Nienhuis 《Hydrobiologia》2006,565(1):153-162
This paper examines the relationship between protected and endangered riverine species (target species) and hydrodynamics
in river-floodplain ecosystems, combining ecological and policy-legal aspects of biodiversity conservation in river management.
The importance of different hydrodynamic conditions along a lateral gradient was quantified for various taxonomic groups.
Our results show that (i) target species require ecotopes along the entire hydrodynamic gradient; (ii) different parts of
the hydrodynamic gradient are important to different species, belonging to different taxonomic groups; (iii) in particular
low-dynamic parts are important for many species and (iv) species differ in their specificity for hydrodynamic conditions.
Many species of higher plants, fish and butterflies have a narrow range for hydrodynamics and many species of birds and mammals
use ecotopes along the entire gradient. Even when focussing only on target species, the entire natural hydrodynamic gradient
is important. This means that the riverine species assemblage as a whole can benefit from measures focussing on target species
only. River reconstruction and management should aim at re-establishing the entire hydrodynamic gradient, increasing the spatial
heterogeneity of hydrodynamic conditions. 相似文献
6.
Long-term assessments of species assemblages are valuable tools for detecting species ecological preferences and their dispersal
tracks, as well as for assessing the possible effects of alien species on native communities. Here we report a 50-year-long
study on population dynamics of the four species of land flatworms (Platyhelminthes, Tricladida, Terricola) that have colonized
or become extinct in a 70-year-old Atlantic Forest regrowth remnant through the period 1955–2006. On the one hand, the two
initially most abundant species, which are native to the study site, Notogynaphallia
ernesti and Geoplana multicolor have declined over decades and at present do not exist in the forest remnant. The extinction of these species is most likely
related with their preference for open vegetation areas, which presently do not exist in the forest remnant. On the other
hand, the neotropical Geoplaninae 1 and the exotic Endeavouria septemlineata were detected in the forest only very recently. The long-term study allowed us to conclude that Geoplaninae 1 was introduced
into the study area, although it is only known from the study site. Endeavouria septemlineata, an active predator of the exotic giant African snail, is originally known from Hawaii. This land flatworm species was observed
repeatedly in Brazilian anthropogenic areas, and this is the first report of the species in relatively well preserved native
forest, which may be evidence of an ongoing adaptive process. Monitoring of its geographic spread and its ecological role
would be a good practice for preventing potential damaging effects, since it also feeds on native mollusk fauna, as we observed
in lab conditions.
Júlio Pedroni: Granted by CNPQ–Brazil. 相似文献
7.
8.
Prey intake by Atlantic salmon Salmo salar and brown trout Salmo trutta was measured across different riparian vegetation types: grassland, open canopy deciduous and closed canopy deciduous, in upland streams in County Mayo, Western Ireland. Fishes were collected by electrofishing while invertebrates were sampled from the benthos using a Surber sampler and drifting invertebrates collected in drift traps. Aquatic invertebrates dominated prey numbers in the diets of 0+ year Atlantic salmon and brown trout and 1+ year Atlantic salmon, whereas terrestrial invertebrates were of greater importance for diets of 1+ and 2+ year brown trout. Terrestrial prey biomass was generally greater than aquatic prey for 1+ and 2+ year brown trout across seasons and riparian types. Prey intake was greatest in spring and summer and least in autumn apart from 2+ year brown trout that sustained feeding into autumn. Total prey numbers captured tended to be greater for all age classes in streams with deciduous riparian canopy. Atlantic salmon consumed more aquatic prey and brown trout more terrestrial prey with an ontogenetic increase in prey species richness and diversity. Atlantic salmon and brown trout diets were most similar in summer. Terrestrial invertebrates provided an important energy subsidy particularly for brown trout. In grassland streams, each fish age class was strongly associated with aquatic, mainly benthic invertebrates. In streams with deciduous riparian canopy cover, diet composition partitioned between conspecifics with older brown trout associated with surface drifting terrestrial invertebrates and older Atlantic salmon associated with aquatic invertebrates with a high drift propensity in the water column and 0+ year fish feeding on benthic aquatic invertebrates. Deciduous riparian canopy cover may therefore facilitate vertical partitioning of feeding position within the water column between sympatric Atlantic salmon and brown trout. Implications for riparian management are discussed. 相似文献
9.
LAURENCE M. COOK 《Biological journal of the Linnean Society. Linnean Society of London》2007,90(1):49-53
A test has been made of the association of heterozygosity with shell breadth in the polymorphic snail Cepaea nemoralis. The material was collected by C. B. Goodhart from a series of paired sites at which individuals reached different adult breadths. Dominant phenotypes, in which a large fraction was heterozygous, had a greater breadth and lower variance than recessive phenotypes regardless of whether the measurement was of shell ground colour, banding or the double recessive vs. the rest. Most of the difference was contributed by samples from the habitat where animals reached the largest size. The result is consistent with existence of heterotic sections of chromosome that include the colour and banding loci, and may help to explain the persistence of the polymorphism. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 90 , 49–53. 相似文献
10.
The use of plantations to manage extensive tracks of deforested lands in the tropics is a conservation strategy that has recently received considerable attention. Plantation trees can promote seed dispersal by attracting dispersers and creating favorable site conditions, leading to increased germination and establishment of indigenous trees. Subsequently, plantation trees can be harvested for profit or left to senesce, leaving a native tree community. We evaluated the effect of vine, grass, and shrub cutting (weeding) over a 3‐year period on regeneration of indigenous trees subsequent to the removal of plantation softwoods in Kibale National Park, Uganda. Counter to what would be expected if weeding released trees from competition, we found no difference in the total number of stems or in the stems greater than 10 cm diameter at breast height between control and weeded plots; there were more stems greater than 1 cm diameter at breast height in the control plots. For species found in both control and weeded plots, the maximum size of individuals did not differ. At the end of the study, 61 species were found in the control plots and 43 species were found in the weeded plots, and in both types of plots the three most abundant species were the same. The number of species and stems classified as early or middle successional species did not differ between weeded and control plots. The fact that weeding did not promote regeneration of indigenous trees after the removal of plantation trees illustrates the importance of evaluating and field‐testing potential management options. 相似文献