Search results for "Systematics"

Population Structure and Habitat Selection by Anisakis simplex in 4 Odontocete Species from Northern Argentina

2003

We described the population structure and habitat selection of Anisakis simplex in 46 franciscanas, Pontoporia blainvillei, 8 Burmeister's porpoises, Phocoena spinnipinis, 2 Dusky dolphins, Lagenorhynchus ob- scurus, and 2 common dolphins, Delphinus delphis, caught incidentally in the coastal fisheries of northern Argentina. Prevalence ranged from 50% to 100%, but mean intensities were low (1.0-3.6), suggesting that A. simplex has low recruitment rates to coastal dolphins in this area. Adult nematodes were found exclusively in the main stomach of 64.5% of franciscanas (the first stomach of this species) and the forestomach of 50% of Burmeister's porpoises and Dusky dolphins. Other developme…

Fishless-stream mayflies express behavioural flexibility in response to predatory fish

1996

The fish avoidance behaviour of nymphs of the grazing mayfly Baetis rhodani (Ephemerop- tera) was examined. The nymphs originated from a fishless stream. To study their responses to the addition of predator cues, nymphs were exposed to (1) chemical cues from a caged fish, or (2) a freely moving diurnal fish (European minnow, Phoxinus phoxinus). The nymphs immediately increased their refuge use when exposed to a live fish, whereas chemical cues alone did not cause any avoidance responses. In a second experiment, the eVects of (1) fish chemicals and (2) a fish model plus fish chemicals on the diel refuge use patterns of Baetis nymphs were examined. In the presence of a fish model, more nymphs…

The mammalian geochronology and biogeography of Paşalar (Middle Miocene, Turkey)

1990

Abstract The Pasalar fauna includes 56 mammalian species of European. Asian, African and North American origin. Evidence provided on the stage-of-evolution of the primates Sivapithecus darwini and cf. Kenyapithecus, the rodent Turkomys pasalarensis, insectivores, carnivores, rhinos, suids and ruminants suggests that Pasalar is correlative with the Late Langhian marine stage and European Mammal Neogene Zone 6., circa 15 Ma (million years ago). A review of the Pasalar fauna's biogeographic history suggests that it was aggregated by a succession of pulsed intercontinental geographic extensions tied to global sea-level lowering events during the earlier half of the Miocene.

Typification of the marine siphonous green algae Caulerpa prolifera (Bryopsidales, Chlorophyta)

2015

The typification of the marine siphonous green algae Caulerpa prolifera (Forsskål) J.V. Lamouroux (≡ Fucus prolifer Forsskål) (Caulerpaceae), including f. obovata (J. Agardh) Weber-van Bosse and f. zosterifolia Børgesen, is discussed. Original material conserved in the Natural History Museum of Denmark (Copenhagen) at C (Herbarium Forsskålii) and in the Botanical Museum of Lund University at LD are designated as the corresponding lectotypes.

Notes: FOOD AND PARASITES FROM TWO HOURGLASS DOLPHINS, LAGENORHYNCHUS CRUCIGER (QUOY AND GAIMARD, 1824), FROM PATAGONIAN WATERS

2003

Combining stable isotope and intestinal parasite information to evaluate dietary differences between individual ringed seals (Phoca hispida botnica)

2006

The diet and foraging behaviour of nine individual Baltic ringed seals ( Phoca hispida botnica Gmelin, 1785) in the Bothnian Bay were studied by combining results from stable isotope analyses (δ13C and δ15N) with data on intestinal parasites whose occurrence varied among the fish hosts. The patterns of infection with three acanthocephalan parasites, Corynosoma semerme (Forssell, 1904), Corynosoma magdaleni Montreuil, 1958, and Corynosoma strumosum (Rudolphi, 1802), and with a cestode larva, Schistocephalus solidus (Müller, 1776), were examined. The ringed seals become infected with these intestinal parasites by feeding on the fish hosts and hence have different parasite species and differe…

Can large branchiopods shape microcrustacean communities in Mediterranean temporary wetlands?

2011

It was recently suggested that large branchiopods may play a keystone role in temporary aquatic habitats. Using a microcosm experiment manipulating microcrustacean communities of Mediterranean temporary wetlands (Camargue, Southern France), we tested the following hypotheses: (i) large branchiopods (the notostracan Triops cancriformis and the anostracan Chirocephalus diaphanus) can limit microcrustacean densities through both competition and predation; (ii) notostracans create high suspended-matter concentrations through bioturbation, which can negatively impact microcrustaceans; and (iii) the outcome of these biotic interactions is more detrimental at high salinities. We found a strong pr…

Behavioural responses of voles to simulated risk of predation by a native and an alien mustelid: an odour manipulation experiment

2010

Context. Potential mammalian prey commonly use the odours of their co-evolved predators to manage their risks of predation. But when the risk comes from an unknown source of predation, odours might not be perceived as dangerous, and anti-predator responses may fail, except possibly if the alien predator is of the same archetype as a native predator. Aims. In the present study we examined anti-predator behavioural responses of voles from the outer archipelagos of the Baltic Sea, south-western Finland, where they have had no resident mammalian predators in recent history. Methods. We investigated responses of field voles (Microtus agrestis) to odours of native least weasels (Mustela nivalis)…

A comparison of infestation patterns by Ixodes ticks in urban and rural populations of the Common Blackbird Turdus merula

2002

Although spatial variation in the patterns of parasite infestations among host populations may have important ecological and epidemiological consequences, the causes underlying such variation are poorly known. In the context of a long-term study on the population biology of Common Blackbirds Turdus merula , we examined the prevalence and intensity of infestation by Ixodes ticks between birds living in rural vs. urban habitats. The overall prevalence of tick infestations was significantly higher in the rural habitat where 74% of individuals ( n = 130) were infested. This result contrasted markedly with the situation in the urban habitat where less than 2% of individuals ( n = 360) carried ti…

Shoaling behaviour of fish under parasitism and predation risk

2008

Shoaling is a common antipredatory adaptation in several fish species. However, parasite infections may alter shoaling behaviour of fish by impairing fish sensory/motor systems and by reducing the net benefit of shoaling. In an experimental study, we investigated whether Diplostomum spathaceum (Trematoda) eye flukes alter shoaling behaviour of rainbow trout, Oncorhynchus mykiss, and if this has an interaction with predation risk. The parasite reduces the vision of fish by inducing cataract formation, which in previous studies has been shown to alter fish escape responses and crypsis. We found that the shoals of infected fish contained fewer individuals and they divided into separate groups …