摘要:

Diet of two syntopic populations ofRana dalmatinaandR.synkleptonesculentawere studied in order to collect data about competition and niche overlap in relation to habitats frequented. Field observations confirm previous ecological researches and show that the former species has a short aquatic phase during the mating period; it lives in woods after breeding relatively far from water. The edible frog, on the contrary, remains near damp areas during the whole activity period. Trophic niche breadth proved greater inR. dalmatinathan inR.synkleptonesculenta.Niche overlap between species was low, because of the different kind of habitats frequented, while that between sexes was low inR. dalmatina, because males and females show different activity patterns during the year. On the contrary, overlap was complete inR.synkleptonesculenta.No correlation was found between the size of frogs and preys. In conclusion, frogs are opportunistic predators and our results suggest that maintaining a highly diversified habitat is useful for avoiding competition between species.

ISSN:1125-0003    

DOI:10.1080/11250000009356297

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Feeding of tawny owl,Strix aluco, was studied from 14 localities of northern and central Italy, where it preyed mainly upon mammals and birds, but amphibians and invertebrates were also frequently eaten. Predation upon mammals was more important from autumn to spring, when alternative prey (amphibians, birds and invertebrates) were less available. The food niche overlaps, the linear distances (in km) between the various localities were negatively correlated, and the mean size of prey taken increased with the proportion of forested territory. However, where tawny owl preyed upon large forest mammals, it also preyed upon larger mammals not typical of forests. Considering the relationships between forest structure and tawny owl diet, it was found that forest density was positively correlated with the proportion of arvicolids and negatively with prey size diversity and the proportion of myoxids. The amount of forest territory within 1 km radius from each pellet collection site largely explained diet variability. Results of discriminant analysis, in addition, suggested that tawny owl is likely to avoid thick Mediterranean coppice forests as hunting habitats.

ISSN:1125-0003    

DOI:10.1080/11250000009356298

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Counts of squirrel nests (dreys) and vegetation surveys in 32 1‐ha census stations were carried out to estimate densities in different forest types and determine habitat selection of the subspecies of red squirrelSciurus vulgaris meridionalisin the Sila Grande forests, Calabria, South Italy. Dreys were not built randomly, but the majority was constructed at 60–70% of the total height of the nest‐tree, pines and oaks being the preferred tree species. Mean drey densities, 2.75/ha, 2.78/ha, and 2.00/ha in, respectively, Cal‐abrian black pine forest, beech dominated mixed forest, and chestnut woodlands, did not differ between forest types and extrapolated to estimated squirrel densities ranging from 0.44 to 0.61 squirrels/ha. Variation between stations in a tree species diversity index and in distance from the nearest plot of pine woodland significantly affected variation in drey density: squirrels preferred forest habitats dominated by beech, with also black pine and oak available, or chestnut woodlands that were within the range of one (male) squirrel home range diameter (310 m) of a plot of pine forest (mean drey density 5.4/ha). Fewer dreys were found in deciduous (beech or chestnut) woodland >310 m away from areas with pine forest (1.1 dreys/ha). Hence, the availability, at least in the vicinity of the census station, of pine seeds of the Calabrian black pine as main food resource strongly influenced habitat choice.

ISSN:1125-0003    

DOI:10.1080/11250000009356299

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The type material ofSpongilla lacustris, recently found in the Linnean herbarium, is described. Type locality and present distribution are shown. Morphological diagnostic traits are described by SEM microphotography. This is the single species of Porifera out of 12 described by Linnaeus in 1759, with type specimen known. A lectotype is selected from two syntypes.

ISSN:1125-0003    

DOI:10.1080/11250000009356300

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The generaZanclea, HalocoryneandZanclellaare surveyed, with description of all known species, including eight new ones ofZanclea(Z.bomala, Z, divergens, Z. fanella, Z. giancarloi, Z. medusopolypata, Z. retraduis, Z. gilii, Z. hirohitoi), two new species ofHalocoryne(H. frasca, H. pirainoid), and two new ones ofZanclella(Z.diabolica, Z. glomboides). For most species, the description covers the whole life cycle. The hydroids of this group can be symbiotic with either bryozoans, bivalves, or corals and only few species are not substrate‐specialist. Symbiotic relationships led to polymorphism and colony integration with the hosts. The morphologies of hydroid and medusa stages are often not consistent, so that species with very derived hydroids have non‐derived medusae (e.g.,Halocoryne pirainoid), or species with very derived medusae have non‐derived hydroids (e.g.,Zanclella diabolica).The architecture of the newly released medusae ofZanclellais exceptional due to a sharp compression of the exumbrella and of the presence of just two radial canals. A phylogenetic scenario is suggested, in spite of the inconsistencies in the rates of change in the two main stages of the cycle.

ISSN:1125-0003    

DOI:10.1080/11250000009356301

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A new species of Stygarctidae, belonging to the genusPseudostygarctusMcKirdyet al., 1976,Pseudostygarctus apuliae, was found in subtidal sediments of Porto Colombo, near Bari (Adriatic Sea) and is described. The new species has intermediate characters betweenP. triungulatusMcKirdyet al., 1976, andP. mirabilisde Zio Grimaldiet al., 1998. Its major distinctive traits are: the dorsal plates morphology and the cuticle sculpture.

ISSN:1125-0003    

DOI:10.1080/11250000009356302

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

One of the most important theories of evolutionary change arising around the turn of the century, “hologenesis” proposed by Daniele Rosa, has often been misinterpreted and widely ignored, perhaps because of the lack of an English translation. In this paper we discuss the theory of the Italian zoologist, with an emphasis on its historical value and its links with current evolutionary thought. In particular, we detect four main themes within Rosa's work that can be referred to the current evolutionary debate: namely vicariance biogeography, the concept of species as individuals, the dichotomous branching of phylogenetic trees and the concept of apotypic and plesiotypic branches. The evident links between Rosa's hologenesis on the one hand and vicariance biogeography, panbiogeography, and Hennigian cladistics on the other, lead us tq the re‐evaluation of some aspects of Rosa's thought.

ISSN:1125-0003    

DOI:10.1080/11250000009356303

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

VERTEBRATE LIFE (Fifth Edition). F. Harvey Pough, Christine M. Janis, John B. Heiser, Prentice Hall, Upper Saddle River, New Jersey 07458, USA, 1999.

ISSN:1125-0003    

DOI:10.1080/11250000009356304

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

ISSN:1125-0003    

DOI:10.1080/11250000009356286

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor