Search results for " ECOLOGY"
showing 10 items of 2331 documents
New insights into the diversity dynamics of Triassic conodonts
2013
International audience; In this paper, we examine the diversity trends and the evolutionary patterns of Triassic conodonts through a newly powered large-scale data-set compiled directly from the primary literature. Paleodiversity dynamics analyses have been undertaken by working at the species level and using a system of time units based on biozone subdivisions for a fine temporal level resolution. The role of heterogeneous duration of taxa in diversity estimates has been evaluated through the probabilistic profiles. Results reveal three different stages in the diversity behaviour of Triassic conodonts from standing metrics delimited by two inflections at the mid-Anisian and mid-Carnian. Su…
A new species of Crepidostomum (Allocreadiidae: Digenea) from northeastern Finland, with comments on its possible origin
1988
Crepidostomum wikgreni n. sp. is described from the gall-bladder and intestine of the whitefish Coregonus acronius in Lake Yli-Kitka in NE Finland. It is morphologically similar to Crepidostomum farionis, with which it occurs sympatrically and sometimes concurrently; but it differs in that the eggs are much larger, i.e. 96±6.5 μm mean-length, as opposed to 71±4.7 μm mean-length for C. farionis in the same host and locality. It is suggested that the new species has arisen from C. farionis after deglaciation and since c. 8,400 BP, at which time the waters of the Lake Kitka System were isolated from those in the rest of Finland and flowed eastwards into the White Sea Basin. The isolation of th…
Female bank voles ( Clethrionomys glareolus ) prefer dominant males; but what if there is no choice?
1996
Both intra-sexual competition between males and female mate choice have been found to affect mating behaviour in rodents. We studied female choice in the bank vole (Clethrionomys glareolus) under circumstances where male-male competition was excluded and the female could interact and mate freely with the males. Mating behaviour was observed in two situations: (1) the female encountered two males with a clear dominance relationship; and (2) the two males were equal in their social status. In all tests where a female in postpartum oestrus had a choice between males of different social rank she mated with the dominant one. When choosing between an even pair of males there was no difference in …
Predatory behavior in the genusLeptogenys: A comparative study
1997
We studied the predatory behavior of seven species of the genusLeptogenys from Mexico and Cameroon. The ants of this genus are armed with long, thin, curved mandibles articulated at the extreme corners of the anterior margin of the head, permitting them easily to seize oniscoid isopods, the obligate or the principal prey of mostLeptogenys species. Workers hunt these prey, which are able to roll themselves up, solitarily. Foraging behavior comprises sequences of up to eight activities. The prey can be seized by the body (rolled up or not), or alternatively by the edge of the shell, then turned over and stung on the ventral face. A relationship between the mandible size of the workers and the…
Isoëtes todaroana (Isoëtaceae, Lycopodiophyta), a New Species from Sicily (Italy)
2009
Isoetes todaroana, a new species from western Sicily (Italy), is described. Morpholog- ical, anatomical and ecological characters are given. The main differential characters are the presence of only two leaf air chambers, rather than four as in all other known species of the genus, and the shape of the scales, which have two lateral rounded lobes and one central spine-like lobe, together with its peculiar calcophilic habitat. So far, the species is known from a single locality.
A test of male mating and hunting success in the kestrel: the advantages of smallness?
1996
We tested female choice for male wing and tarsus length and body mass in the kestrel (Falco tinnunculus), a species in which males average about 10% smaller than females. We also studied how male characters are related to their hunting success. In the laboratory, females preferred lighter males with shorter tarsi as mates, if the difference in those characters between competing males was larger than average. Lighter and shorter-winged males seemed to be better hunters than heavier and longer-winged males. Field observations in a year in which voles were scarce suggested that shorter-winged males were also better food providers in courtship feeding than longer-winged males,although in good v…
Interspecific extrinsic and intrinsic competitive interactions in egg parasitoids
2012
Interspecific competitive interactions can occur either between adult parasitoids searching/exploiting hosts (extrinsic competition) or between parasitoid larvae developing within the same host (intrinsic competition). Understanding how interspecific competition between parasitoids can affect pest suppression is important for improving biological pest control. The purpose of this work was to review both extrinsic and intrinsic competition between egg parasitoid species. These are organisms that are often candidates for biological control programs due to their ability to kill the pest before the crop feeding stage. We first reviewed the literature about interspecific competitive abilities of…
Metarhizium anisopliae, a potential agent for the control of grape phylloxera
2004
This investigation deals with the control effects of the insect pathogenic fungus Metarhizium anisopliae var. anisopliae on Daktulosphaira vitifoliae. In pot experiments, the soil surrounding phylloxera-infected grapes was inoculated with barley colonised with M. anisopliae. After thirty-two days, ineight of ten Metarhizium-applied pots nofresh phylloxera infections could be observed.In two of ten plants, a few fresh nodositiessingly occupied with phylloxera or phylloxeraeggs could be found. In all untreated plants,fresh nodosities with either single (two of sixplants) or multiple (four of six plants)occupation with phylloxera could be observed.M. anisopliae could be re-isolated in aconcent…
Boat traffic in Lampedusa waters (Strait of Sicily, Mediterranean Sea) and its relation to the coastal distribution of common bottlenose dolphin (Tur…
2010
The volume of boat traffic and its potential connection to the coastal distribution of the common bottlenose dolphin (Tursiops truncatus) was evaluated off Lampedusa Island (Strait of Sicily). From July to September 2006 daily surveys were carried out at eight sites along the coast, three times a day, to assess the number, type, and size of boats moving, fishing, or stationed in Lampedusa waters. The study area was divided into four geographic areas: northwest, northeast, southwest, and southeast. Data were analyzed to determine the difference in the number of boats among the areas, sampling months, and times of day. The presence of dolphins was monitored by standardized land-based observat…
The nutritional composition of selected wild edible mushrooms from Sicily (southern Italy)
2011
The wide consumption of wild fungi by the local population is the basis for an evaluation of the as yet unknown nutritional composition of some selected species. Wild edible mushrooms (Fistulina hepatica, Infundibulicybe geotropa, Laetiporus sulphureus, Macrolepiota procera var. procera and Suillus granulatus) were collected in a number of Sicilian (southern Italian) forest ecosystems and analysed according to standard methodologies of fungal analysis, for their basic composition (ash, water, protein, fat, carbohydrate and vitamin). The results showed that the investigated mushrooms could be suggested as a source of nutritional elements for the human diet.