The ants of the genus Protalaridris are revised based upon their morphology. Seven species are recognized; the type species (P. armata Brown, 1980) and six species described as new: P. aculeata Lattke & Alpert, sp. n., P. arhuaca Guerrero, Lattke & Alpert, sp. n., P. bordoni Lattke, sp. n., P. leponcei Delsinne & Lattke, sp. n., P. loxanensis Lattke, sp. n., and P. punctata Lattke, sp. n. The genus is patchily distributed in mesic forested areas from western Panama to northern Venezuela and along the Andes to the Amazon watershed of southwestern Peru. The generic description is modified to accommodate a short-mandibulate species. Sporadic biological observations of one long-mandibulate species suggest they are sit-and-wait ambush predators that open their jaws to approximately 180° when stalking. All species are described and imaged, an identification key and a distribution map is provided. Comparing the mandibular morphology of long-mandibulate Protalaridris with other extant and extinct ants bearing elongate, dorsoanterior arching mandibles suggests the supposed mandibular apex in these taxa is actually a hypertrophied, preapical tooth and their supposed basal mandibular tooth is the main mandibular shaft., John E. Lattke, Thibaut Delsinne, Gary D. Alpert, Roberto J. Guerrero., and Obsahuje bibliografii
Deserts and semi-deserts, such as the Sahara-Sahel region in North Africa, are exposed environments with restricted vegetation coverage. Due to limited physical surface structures, these open areas provide a promising ecosystem to understand selection for crypsis. Here, we review knowledge on camouflage adaptation in the Sahara-Sahel rodent community, which represents one of the best documented cases of phenotype-environment convergence comprising a marked taxonomic diversity. Through their evolutionary history, several rodent species from the Sahara-Sahel have repeatedly evolved an accurate background matching against visually-guided predators. Top-down selection by predators is therefore assumed to drive the evolution of a generalist, or compromise, camouflage strategy in these rodents. Spanning a large biogeographic extent and surviving repeated climatic shifts, the community faces extreme and heterogeneous selective pressures, allowing formulation of testable ecological hypotheses. Consequently, Sahara-Sahel rodents poses an exceptional system to investigate which adaptations facilitate species persistence in a mosaic of habitats undergoing climatic change. Studies of these widely distributed communities permits general conclusions about the processes driving adaptation and can give insights into how diversity evolves.
The caterpillars of the butterfly Methona themisto (Nymphalidae: Ithomiinae) are conspicuously coloured and feed exclusively on Brunfelsia uniflora (Solanaceae), a plant that is rich in secondary plant substances, which suggests the caterpillars are chemically protected against predators. Results of experiments indicate that predators determine the survival of Methona themisto caterpillars in the field and laboratory bioassays that this organism is eaten by ants and spiders but not chicks. Both the conspicuous orange and black striped colouration and chemical compounds of Methona themisto caterpillars seem to be related to protection against predation by visually hunting predators. Chicks ate proportionally more of the cryptically coloured 1st instar caterpillars than of the conspicuously coloured later instar caterpillars. That Methona themisto caterpillars are chemically defended is supported by the activity of the dichloromethanic extract of 5th instars in preventing predation by chicks. Caterpillars of Methona themisto are aposematic as they are both (1) unpalatable, and (2) their warning signal is easily recognized by potential predators. Chicks learned to avoid the aposematic 3rd or 5th instar caterpillars after one encounter. Mealworms painted to look like caterpillars were also rejected by chicks that had previously encountered Methona caterpillars. Naïve chicks did not avoid eating the painted mealworms, which indicates they do not innately avoid this specific colour pattern.
We studied the diet of the American mink (Neovison vison) in small artificial watercourses located in a farmland area of the valley of the River Barycz in Poland. Rodents, mainly Microtus spp., were the most frequent prey identified, occurring in 88.3 % of all analyzed mink scat. Minks also fed willingly on fish, birds and amphibians, whereas insects, crayfish and reptiles accounted for only a small part of the biomass of food consumed. The food niche breadth of the mink’s diet was wide, and varied significantly between seasons; in spring and autumn minks preyed mainly on rodents and fish, while the winter and summer diets consisted of a broad characterization of prey items. The proportion of mammals in the diet also decreased significantly during the summer months. These patterns differ from those previously reported in Europe, and demonstrate the plasticity of the mink diet across habitats.
In forest ecosystems in the temperate and boreal zones in Europe, red wood ants (RWA, Formica rufa group) have a significant affect as predators and competitors in communities of ground-dwelling arthropods. Therefore, the spatiotemporal distribution and abundance of RWA affect the distribution of many other species. The hypothesis that a reduction in the abundance of RWA in clear-cut areas enables other arthropods to increase in abundance was tested. The study was conducted in NW Poland in 2007 and 2008. A total of 276 1×1 m plots were sampled and 1,696 individuals recorded. The probability of the occurrence of RWA decreased significantly towards the center of clear-cut areas and increased with increasing plant cover. The frequency of Lasius platythorax, Formica fusca and spiders in the plots significantly increased towards the edge of a clear-cut area. Moreover, the occurrence of L. platythorax was negatively associated with the presence of RWA, while that of the Myrmica species was positively associated. The effect of the distance to the edge of a clear-cut area seems to be much more pronounced than the effect of RWA. This suggests that the arthropods studied prefer habitats close to the edge that are utilized by RWA than RWA-free sites located in the centre of clear-cut areas. and Michal Zmihorski.
Predators activate a search image process for the most frequent prey type as a result of repeated chance encounters with that prey. In addition, selective attention to a limited subset of prey visual features should increase the precision with which the prey is discriminated from the background. In our experiment, we investigated the effects of multiple backgrounds on prey detection by captive American kestrels (Falco sparverius). We predicted that the background itself can serve to cue attention towards the prey type and that a most recent experience provided predictive information. As expected, we observed the effects of search image formation where the background was informative (familiar substrate). Nevertheless, search image effects disappeared with extended practice and kestrels rapidly increased the use of unfamiliar background where prey were completely non-cryptic. Our data suggest that short-term changes in prey detection of a predator cue with the background upon which this prey is found. We discussed the results in the light of related studies on neophobia, visual acuity and achromatic and chromatic contrasts.
We studied diet and prey preferences of the Eurasian lynx (Lynx lynx) inhabiting south-east Poland, based on kills found during GPS-GSM telemetry and opportunistic winter tracking. Among 64 lynx kills were roe deer (Capreolus capreolus) (91%), red deer (Cervus elaphus) (3%) and brown hare (Lepus europaeus) (6%). From the ungulate community, lynx selected roe deer (D = 0.845) and avoided all other ungulates. We recorded one case of surplus and two cases of parallel killing. Lynx visited the same killed roe deer on average for 2.3 days, and for up to six days when surplus or parallel killing occurred. High numbers of the roe deer in south-east Poland supports the persistence of the lynx, but we urge managers to take under consideration food requirements of the lynx when planning game management.
The prey of 66 free-ranging urban and rural house cats Felis catus was studied in a mainland area in SW Finland. The data included 1624 home-brought prey animals, of which 92 % could be identified at least to the class level. The mean number of prey brought home was 4.1 per cat per month (excluding winter). Rodents were the most common prey (72 %), 18 % of prey being birds, 5.4 % insectivores, and the rest other mammals (hares, least weasels, pine martens, and a bat), reptiles or amphibians. Six “super predator” cats accounted for 40 % of all prey items captured. There were no differences between the sexes in the number or diversity of prey
brought home. The prey of young cats was more diverse than that of older, more experienced cats. Especially old cats in rural areas benefit humans by killing many rodents. The proportion of birds captured was 24 % in urban areas where cats represent a possible threat to native birds: probably > 1 million prey animals are monthly killed by free-ranging cats in Finland, at least 144000 of these being birds. “Super predator” cats should thus be kept in the house, especially in urban areas, to prevent predation on birds.
The consumption and preferences of polyphagous ground beetles (Coleoptera: Carabidae) for the seeds of herbaceous plants was determined. The seeds were stuck into plasticine in small tin trays and exposed to beetle predation on surface of the ground. In the laboratory the effect of carabid (species, satiation) and seed (species, size) on the intensity of seed predation was investigated. The consumption of the generally preferred Cirsium arvense seed by 23 species of common carabids increased with body size. Seed of Capsella bursa-pastoris was preferred by small carabids and their consumption rates were not related to their size. The average daily consumption of all the carabid species tested (0.33 mg seeds . mg body mass-1 . day-1) was essentially the same for both kinds of seed. Because of satiation the consumption of seed of C. arvense provided ad libitum to Pseudoophonus rufipes decreased over a period of 9 days to 1/3-1/4 of the initial consumption rate. Preferences of P. rufipes (body mass 29.6 mg) and Harpalus affinis (13.4 mg) for the seeds of 64 species of herbaceous plants were determined. The small H. affinis preferred smaller seed than the large P. rufipes. Predation of seed present on the ground in the field was studied in 1999-2000, at Praha-Ruzyne (50°06´ N 14°16´E). Seeds were placed in stands of different crops as in the laboratory experiments and vertebrate predation was excluded by wire mesh cages. Pitfall traps placed near the cages revealed that carabids were the only seed predators active in the area. Rates of removal of seed of 6 weed species varied with crop, season, seed and site. Average rate of removal in June-August was 2.5 seeds.day-1.tray-1 and was smaller before and after this period. The rates of removal increased with increasing activity density of the carabids and paucity of seed from naturally occurring weeds, which may have satiated the carabids. In stands of winter wheat, millet and soybeans there were significant differences in the rates of removal of the seed of 43 herbaceous species. The field preferences were correlated with those established in the laboratory. Predation of seed on the ground in arable fields can be as high as 1000 seeds.m-2.day-1 and may selectively influence the quantity of seed of particular herb species that enters the soil seed bank. Seed predation thus may be an effective component of weed control on arable land, particularly at low weed densities.