Competition for foraging resources and coexistence of two syntopic species of Messor harvester ants in Mediterranean grassland

1. Diet composition of two syntopic species of Messor seed‐harvester ants (M. wasmanni Krausse and M. minor André) was evaluated during different periods over the year (May, July, October), by analysing food type (plant parts and species) and food size (weight, length, width). Morphological traits of foragers (head width and femur length) considered important features promoting diet partitioning were measured. 2. We used two robust randomisation algorithms (RA2 and RA3), adopted in niche overlap studies, to check for random vs non random utilisation of resources at intra‐ and interspecific level for the different periods. 3. Analyses showed high levels of overlap in the diet of the two species and no evidence of interspecific competition during most of the activity season. In particular, there was an aggregated use of resources in summer, whilst niche partitioning and evidence of competition when resources decreased in autumn. Intraspecifically, no evidence of competition was found. 4. Results suggest two different mechanisms for minimising competition: when food resources are abundant (summer), ants collected the same plant species but selected different sizes; when food resource is scarce (autumn), ants foraged on different plants. 5. The importance of different factors (morphological, behavioural, ecological) possibly affecting competition and coexistence are discussed.     

Variation in the assessment of adequacy in cervical smears

OBJECTIVE: To assess the interobserver reproducibility of the diagnosis of 'adequacy' of cervical smears according to the Bethesda System criteria in cervical smears. STUDY DESIGN: 358 cervical smears were obtained from three Italian cytopathological centres in 1998-99. All centres provided consecutively collected smears. The cervical smears were independently and blindly assessed by four cytologists.The screening was performed using a 10x objective and an additional evaluation of the percentage of cellularity was performed using a 4x objective. RESULTS: The proportion of smears assessed by the four cytologists as 'adequate' ranged from 60% to 70%, the proportion of 'satisfactory for evaluation but limited by' ranged from 27% to 38%, and the proportion of 'inadequate smears' ranged from 2% to 4%. Full agreement in the assessment of smear adequacy was observed in 311 slides and disagreement was observed only in 47. The category 'inadequate smear' was less reliable than the other two; however, the kappa value observed was acceptable. CONCLUSION: The present study shows that it is possible to achieve a high reproducibility in the assessment of smear adequacy, at least among expert cytologists who follow the Bethesda System criteria strictly.     

Survival in the Rockies of an endangered hybrid swarm from diverged caribou (Rangifer tarandus) lineages

In North America, caribou ( Rangifer tarandus ) experienced diversification in separate refugia before the last glacial maximum. Geographical isolation produced the barren-ground caribou ( Rangifer tarandus groenlandicus ) with its distinctive migratory habits, and the woodland caribou ( Rangifer tarandus caribou ), which has sedentary behaviour and is now in danger of extinction. Herein we report on the phylogenetics, population structure, and migratory habits of caribou in the Canadian Rockies, utilizing molecular and spatial data for 223 individuals. Mitochondrial DNA analyses show the occurrence of two highly diverged lineages; the Beringian–Eurasian and North American lineages, while microsatellite data reveal that present-day Rockies' caribou populations have resulted from interbreeding between these diverged lineages. An ice-free corridor at the end of the last glaciation likely allowed, for the first time, for barren-ground caribou to migrate from the North and overlap with woodland caribou expanding from the South. The lack of correlation between nuclear and mitochondrial data may indicate that different environmental forces, which might also include human-caused habitat loss and fragmentation, are currently reshaping the population structure of this postglacial hybrid swarm. Furthermore, spatial ecological data show evidence of pronounced migratory behaviour within the study area, and suggest that the probability of being migratory may be higher in individual caribou carrying a Beringian–Eurasian haplotype which is mainly associated with the barren-ground subspecies. Overall, our analyses reveal an intriguing example of postglacial mixing of diverged lineages. In a landscape that is changing due to climatic and human-mediated factors, an understanding of these dynamics, both past and present, is essential for management and conservation of these populations.     

Ribosomal Discrimination of tRNAs

Mutations in two proteins of the 30S ribosomal subunit indicate that the ribosome provides a recognition screen for tRNAs before, or simultaneous with, their interaction with mRNA.     

Patterns of Amazonian area relationships based on raw distributions of papilionid butterflies (Lepidoptera: Papilioninae)

Diversifications within a biota are due to several factors. Although some of these are untestable with current analytical methods, hierarchical congruence obtained with different cladistic methods and based on independent taxa are undoubtedly important. In the recent past, most hypotheses of historical biogeography (e.g. refugial, riverine, disturbance, vicariance) were tested on the Amazonian biota, selecting a number of diverse organisms such as plants, anurans, lizards, butterflies, birds and monkeys. In this study we used parsimony analysis of endemicity to infer historical relationships among 16 interfluvial areas in the Amazonian lowlands based on raw distributions of 114 Papilioninae (Lepidoptera). The analysis yielded two most parsimonious trees of area relationships. One tree was characterized by two main clusters of areas which showed a separation of Guyanan + south-east Amazonian interfluvial areas from western Amazonian interfluvial areas. The second tree showed the Guyanan interfluvial areas basal to a cluster which included all the other interfluvial areas. This latter cluster was subdivided into two main groups of areas separating the south-east Amazonian and the western Amazonian interfluvial areas. This result is discussed in the light of previous hypotheses obtained with the same method using some vertebrate taxa in the Amazonian lowlands. Likewise, comparisons with other hypotheses on lineages of birds, mammals and butterflies obtained applying cladistic biogeographical methods are made. The two alternative vicariant patterns presented for papilionid butterflies are strictly congruent with those for birds.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 82 , 345–357.     

Decline and recovery in otter Lutra lutra populations in Italy

• 1 Changes in otter Lutra lutra distribution in Italy were examined by analysing geographical, historical and survey data.
• 2 As in other European countries, otters declined sharply in Italy during the late 1970s and throughout the 1980s. Between 1985 and 2004 the species became extinct, except for some reintroductions, in northern and most of central Italy while the species appears to have substantially recovered in its southern range. This recovery of the otter population is apparently not due to increased research effort, but reflects a real expansion of range.
• 3 Differences in the degree of range reduction during the second half of the 20th century and in the availability of suitable habitats are probably the major factors that have determined the two opposite trends shown by otter populations in the last 20 years.
• 4 Better knowledge of otter status and distribution is needed for effective conservation management. We suggest that a national survey of the Italian otter population that employs genetic approaches should represent a first step of the national action plan for otter conservation.

     

Do non‐native fish as prey favour the conservation of the threatened indigenous Eurasian otter?

1. Biological invasions are considered a major threat to biodiversity. Most research has focused on the distribution, biology and impacts of non‐native species on native fauna and flora. However, few studies have explored their role as prey for native predators of conservation concern. 2. To assess the incidence and intensity of predation by the Eurasian otter Lutra lutra on established non‐native fish species, data were collated from the published literature. To be selected, studies had to cover at least 1 year, analyse more than 100 spraints and report the study period and percentage relative frequency (%RF) of all prey fish species. 3. To permit reliable, time‐related comparisons with %RF of non‐native fishes in otter diet, we also reviewed available information about both the distribution of non‐native fishes and history of their introductions to European countries, revealing a decrease with longitude in the number of naturalised non‐native fishes taken (ranging between 5 and 34) and their percentage in each fish assemblage. 4. Our selective criteria were met by 30 dietary studies from 44 study areas in 15 European countries during 1970–2010. The extent to which otters rely on non‐native fishes was almost negligible (mean %RF = 4.8), with the number of non‐native fishes preyed upon by otters decreasing with both latitude and longitude. 5. The %RF of non‐native fish in the diet increased slightly with time, with otters preying significantly more on non‐native fish in study areas where alterations of the fish assemblage had been highlighted in the reference papers. No relationship was found between otter diet breadth and the occurrence of non‐native fishes in their diet. 6. The current role of non‐native species in otter diet suggests that effective otter conservation management plans should focus on the maintenance and/or enhancement of native fish assemblages.