Search results for "Animal Ecology"
showing 10 items of 120 documents
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…
Characterisation of the external features ofSchistocephalus solidus (M�ller, 1776) (Cestoda) from different geographical regions and an assessment of…
1995
A comparative study of some morphological (segment number, scolex morphology and biometry, length and weight) and biological (maturation in different hosts) features ofSchistocephalus solidus plerocercoids and adults from different geographical regions (Baltic Sea and the British Isles) was carried out. The length of the plerocercoids fromGasterosteus aculeatus was shown to be the variable that best correlated with segment number. A very clear bimodal distribution of segment numbers separated the majority of British and Baltic plerocercoids (British n=21, mean length 25.48, SD 5.63, range 14–34 mm; mean segment number 66.33, SD 8.68, range 51–86. Baltic n=30, mean length 33.23, SD 4.64, ran…
Behavioral response of the egg parasitoid Ooencyrtus telenomicida to host-related chemical cues in a tritrophic perspective
2010
The response of the generalist egg parasitoid Ooencyrtus telenomicida (Vassiliev) (Hymenoptera: Encyrtidae) to host-related chemical cues from tomato plants, Solanum lycopersicum L., and adults of Nezara viridula (L.) (Heteroptera: Pentatomidae) was investigated in laboratory-based no-choice and paired-choice tests. In Y-tube olfactometer experiments, when female wasps were exposed to volatiles from plants in different conditions, they were attracted only to volatiles produced by N. viridula adult-infested tomato plants. When female wasps were exposed to adults of N. viridula, they were attracted to volatiles from virgin males, and, at a lower level, to volatiles from mated females in preov…
The predatory mirid Dicyphus maroccanus as a new potential biological control agent in tomato crops
2014
The first record of the omnivorous predator Dicyphus maroccanus Wagner (Hemiptera: Miridae) inhabiting tomato crops in the Valencia region (East Coast of Spain) was in 2009. Since then, D. maroccanus has often been found preying on the eggs of Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) in this area. To evaluate this predator’s potential as a biological control agent, its life-history traits in the presence and absence of prey [(eggs of Ephestia kuehniella Zeller (Lepidoptera: Pyralidae)] on tomato plants were studied under laboratory conditions. Immature stages that preyed on eggs of E. kuehniella developed successfully. However, no nymph completed development on the plant without t…
Melanin-based colour polymorphism signals aggressive personality in nest and territory defence in the tawny owl (Strix aluco)
2013
Nest and territory defence are risky and potentially dangerous behaviours. If the resolution of life history trade-offs differs between individuals, the level of defence may also vary among individuals. Because melanin-based colour traits can be associated with life history strategies, differently coloured individuals may display different nest and territory defence strategies. We investigated this issue in the colour polymorphic tawny owl (Strix aluco) for which plumage varies from dark to light reddish melanic. Accordingly, we found that (1) our presence induced a greater response (flying around) from dark-coloured than light-coloured females and (2) dark reddish males suffered lower nest…
Species size affects hatching response to different temperature regimes in a rotifer cryptic species complex
2013
The strategy of decreasing size with increasing temperature known as Bergmann’s rule operates at geographic scale and in spite of extensive studies still presents a puzzle to researches. The aim of this work was to verify whether patterns of diapausing egg hatching of closely related species are consistent with the expectations from Bergmann’s rule. In a laboratory study of the cryptic species complex of the rotifer Brachionus plicatilis, the response to temperature (17.5, 22.5, and 25.0 °C) of diapausing eggs collected in a pond where the three tested species coexist was assessed by (1) the number of hatchlings emerging or (2) the time needed to hatch. Our results show that the response to…
Influences of geographic differentiation in the forewing warning signal of the wood tiger moth in Alaska
2014
Aposematic organisms have warning signals advertising their unpalatability to predators, and because signal efficiency is better in higher densities, positive frequency-dependent selection is expected to select against less common signals. The wood tiger moth (Parasemia plantaginis) occurs across the Holarctic and its conspicuous hindwings serve as warning signals to predators. It also has conspicuous black and white forewing patterns that could act as warning signals, or help to hide the moth by preventing predators from seeing the outline of the moth’s body (a strategy known as disruptive coloration). In Alaska, the predominant forewing pattern changes distinctly between the regions aroun…
On the evolutionary stability of female infanticide
1997
Territoriality among female rodents may have evolved as an adaptation to intraspecific competition for resources or, alternatively, to defend pups against infanticide. In order to evaluate the latter, we analyse the conditions that allow an infanticidal strategy to invade a population of non-infanticidal females, and the circumstances under which infanticide may become an evolutionarily stable strategy (ESS). Our game theoretical analyses indicate that infanticide has to be associated with some direct (cannibalism) or indirect (reduced competition) resource benefits in order to invade a non-infanticidal population. We also expect that females will primarily kill litters of nearby neighbors,…
Determinants of jaguar occupancy at the northern range edge
2020
Identifying factors promoting jaguar (Panthera onca) occupancy is crucial for planning effective conservation and management actions that can contribute to long-term population viability. We used camera-trapping and modeled factors affecting detection and occupancy for jaguars in Sonora at 149 sites during August-November 2008 and 2009. We measured 24 covariates presumed to affect detection (n = 6) and occupancy (n = 18) at camera sites, including sampling period and various habitat characteristics. We obtained 29 jaguar detections at 19 sites (naive occupancy = 0.12) in 5455 trap-days of effort. Jaguar detectability (p = 0.16 +/- 0.05) was negatively affected by human presence and varied b…
Breeding suppression in the bank vole as antipredatory adaptation in a predictable environment
1994
In northern Fennoscandia, microtine rodent populations fluctuate cyclically. The environment of an individual vole can be considered to be predictable when the risks of predation and intra- and interspecific competition change with the cycle, such that both are high during the population highs of voles. The risk of predation is also high during the vole crash. After the crash, the vole population is characterized by low intra- and interspecific competition and low predation pressure. The main predators affecting voles during the crash are the small mustelids, least weasel and stoat. The density of these specialist predators declines drastically during the winter after the vole crash. We stu…