Seasonal differences in energy requirements of Garden Warblers Sylvia borin migrating across the Sahara desert

The Sahara desert acts as an ecological barrier for billions of passerine birds on their way to and from their African wintering areas. The Garden Warbler Sylvia borin is one of the most common migrants involved. We used body mass of this species from Greece in autumn and spring to simulate the desert crossing and to assess how body mass relates to fuel requirement. The flight range estimates were adjusted to the seasonal extent of the desert, 2200 km in autumn and about 2800 km in spring. In autumn, with an average fuel load of about 100% of body mass without fuel, birds were not able to cross the desert in still air, but northerly winds prevail during September and with the average wind assistance only one in 14 was predicted to fail to make the crossing. Body mass data from spring, after the desert crossing, was used to estimate departure body mass from south of the desert. The average wind assistance in spring is close to zero and departure body mass of the average bird arriving at Antikythira, a small Greek island, under such conditions was estimated to be 34.6 g, which corresponded to a fuel load of 116%. Calculations based on 1% body mass loss per hour of flight showed slightly larger body mass loss than that calculated from flight range estimates. The results suggest that passerine birds about to cross the eastern part of the Sahara desert need to attain a larger fuel load in spring than in autumn.     

Dispersal and population structure of two sympatric species of the mediterranean land snail genus Mastus (Gastropoda, Pulmonata, Enidae)

We studied the population dynamics of Mastus by investigating the effects of population structure, spatial ecology and biology of reproduction on the genetic diversity of two sympatric Mastus species endemic to the island of Crete. Over a period of 27 months, we carried out both mark–recapture and random quadrat sampling techniques in order to assess the dispersal trends, the aggregation patterns, the neighbourhood size and the habitat preferences of these species. There were 154 recorded movements for M. butoti and 114 for M. cretensis . Mean monthly dispersal was estimated at d  = 0.5 m for M. butoti and d  = 1 m for M. cretensis . Both species showed a random dispersal pattern but tended to aggregate in the field. Their populations were found to be highly structured owing to their highly parsimonious dispersal behaviour and the very low population densities, estimated at D  = 2.07 ± 0.16 and D  = 0.73 ± 0.16 individuals m⁻² for M. butoti and M. cretensis , respectively. The neighbourhood size did not exceed 150 individuals for either species. The habitat occupied by each species changed during the active season, but both the immature and the adult individuals of each species seemed to prefer the same habitats throughout the active season. Partial population activation during the active season was observed in both species. We conclude that the population structure, the partial population activation and the species-specific reproductive strategies have a profound effect on maintaining the genetic diversity of the genus' populations.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 83 , 131–144.     

The species–area relationship in centipedes (Myriapoda: Chilopoda): a comparison between Mediterranean island groups

The present study article examines the shapes of centipede species–area relationships (SARs) in the Mediterranean islands, compares the results of the linear form of the power model between archipelagos, discusses biological significance of the power model parameters with other taxa on the Aegean archipelago, and tests for a significant small‐island effect (SIE). We used 11 models to test the SARs and we compared the quality‐of‐fit of all candidate models. The power function ranked first and Z‐values was in the range 0.106–0.334. We assessed the presence of SIEs by fitting both a continuous and discontinuous breakpoint regression model. The continuous breakpoint regression functions never performed much better than the closest discontinuous model as a predictor of centipede species richness. We suggest that the relatively low Z‐values in our data partly reflect better dispersal abilities in centipedes than in other soil invertebrate taxa. Longer periods of isolation and more recent island formation may explain the somewhat lower constant c in the western Mediterranean islands compared to the Aegean islands. Higher breakpoint values in the western Mediterranean may also be a result of larger distance to the mainland and longer separation times. Despite the differences in the geological history and the idiosyncratic features of the main island groups considered, the overall results are quite similar and this could be assigned to the ability of centipedes to disperse across isolation barriers. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 146–159.     

Mitochondrial DNA phylogeny and morphological diversity in the genus Mastus (Beck, 1837): a study in a recent (Holocene) island group (Koufonisi, south-east Crete)

Three endemic Cretan land snail species of the genus Mastus (Beck, 1837) from the island group of Koufonisi (south-east Crete) and the eastern part of Crete, were studied by multivariate analysis of shell morphology and analysis of mtDNA sequences. The phylogeny of the populations studied and the processes effecting the genetic and morphological diversity of the species were investigated. Extremely high mtDNA sequence divergence was observed both within and between populations. The Cretan populations could not be distinguished morphologically, while the populations of the islets were more distinct. We argue that the active geological past of the area (including sea level changes) and the long-term presence of humans has produced a mixing up of Mastus populations leading to the accumulation of high divergence of mtDNA sequences on a small spatial scale. The limited morphological diversity and the distinct shell 'identity' of the islets' populations can be attributed to the selective pressures of the island group.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 78, 383–399.     

Isolation and characterization of polymorphic microsatellite markers in the wall lizard Podarcis erhardii (Squamata: Lacertidae)

Five polymorphic microsatellite loci (containing di‐ and penta‐nucleotide repeats) were developed for the Erhard's wall lizard, Podarcis erhardii, an endemic species of southern Balkan Peninsula. The number of alleles ranged from five to 17. Observed and expected heterozygosities ranged from 0.28 to 0.92 and 0.57 to 0.91, respectively. These markers will provide a valuable tool for population genetics analyses and can contribute to the evaluation of conservation programs.     

Isolation and characterization of six polymorphic microsatellite markers in the freshwater turtle Mauremys rivulata (Testudines: Geoemydidae)

Six polymorphic microsatellite loci containing dinucleotide repeats were developed for the freshwater turtle Mauremys rivulata. The number of alleles ranged from five to 18. The observed and expected heterozygosities ranged from 0.19 to 0.79 and 0.46 to 0.90, respectively. These markers may serve as a valuable tool for population genetics analyses and provide information on the evolutionary history of the species.     

Isolation and amplification of shrew DNA from barn owl pellets

The last decade has seen a number of studies reporting the extraction of DNA from ancient sources, such as fossil bones. Owl pellets, which contain an excellent skeletal record of small mammals consumed, can be used in a non-invasive sampling method for genetic studies of free-ranging animals without the need for direct capture or even observation. Such a non-invasive sampling method will allow us to address questions that cannot be answered using conventional methods and will lead to a more integrated study of micromammals. In the present study, various protocols used for ancient DNA extraction were investigated, in order to determine the applicability of owl pellets as a source of DNA for phylogenetic and phylogeographical studies of micromammals. Of the 12 bone samples used in this study, 11 gave sequences of expected species ( Crocidura , Rattus and Mus ) and size (around 300 bp), using the pair of primers L14841/H15149, which target a highly conserved region of the cytochrome b gene. The results obtained demonstrate that mitochondrial DNA can be isolated and amplified using bones of micromammals found in barn owl ( Tyto alba ) pellets. The recovery of genetic data from owl pellets will enable the identification of prey species for several phylogenetic and phylogeographical studies of small mammals (Muridae and Insectivora) appearing in the owl's diet. The main advantages of this new approach are that (a) the pellets are very easy to find and collect, (b) the pellets can potentially provide a large number of individuals of small mammals, and (c) the method can cover a wide geographical area complementary to the range of owls of this type.  © 2005 The Linnean Society of London, Biological Journal of the Linnean Society , 2005, 85 , 331–340.