Search

The article describes the cross-amplification of microsatellite loci for several Testudo species. Species examined include T. hermanni, T. hercegovinensis, T. marginata and T. graeca. 23 microsatellite loci were tested, with 12 being discarded. The 11 microsatellite loci gave reliable and repeated genotyping results in all tested Testudo species/subspecies. A total of 8-10 polymorphic loci was defined across the tested microsatellite genetic markers. Results of the study confirmed the validity of cross-amplification tests across taxa which are phylogenetically distant.

Scylla serrata (Decapoda: Portunidae) is a swimming crab that is widespread in the Indo-Pacific region and commonly found in estuarine and mangrove waters. An extended planktonic larval phase suggests high dispersal potential and the possibility of extensive gene flow between conspecific populations at least on a geographic mesoscale (tens to hundreds of kilometres).Intraspecific variation of the mitochondrial DNA cytochrome oxidase subunit I (mtDNA COI) gene was investigated in 77 individuals from four representative mangrove swamps of the African tropics (Kenya and Zanzibar) by means of DNA sequencing. We examined 535 base pairs (bp) and identified 24 different haplotypes. Each population sample is characterised by a single most frequent haplotype, shared among all four populations, and a small number of rare ones, typically present in only one or two individuals and representative of a specific population.Analysis of molecular variance (AMOVA), FST statistics and χ2 contingency analysis of spatial distribution of mtDNA haplotype frequencies revealed in toto a significant genetic differentiation among populations. These results could indicate that gene flow might be reduced, even between geographically close sites, despite the high potential for dispersal; anyway, at the recorded level of divergence and owing to the abundance of rare haplotypes and singletons in our data set, repeated sampling over time is necessary to establish whether the recorded pattern of genetic differentiation is stable and biologically significant.Finally, integration of our data with those reported by Gopurenko et al. [Mar. Biol. 134 (1999) 227] on S. serrata from South Africa, Red Sea and Mauritius Islands allowed to infer S. serrata population structure within a larger area of the Indian Ocean region. [Copyright &y& Elsevier]

Activity and clustering in two intertidal species of hermit crabs, Clibanarius virescens and Calcinus laevimanus, were studied during a semilunar tide cycle in Somalia. Three groups were marked and examined throughout 16 low waters, and 12 samples of clustered and scattered crabs were collected from similar habitats. During high water, the animals took refuge in mass in holes of the cliff; they began to reappear (especially at night) and feed during ebb‐tide (feeding phase). When exposed to the air, the crabs entered a resting phase with some aggregating in clusters, then when the tide rose became active again before going back to their refuges. Clusters composed of up to 95 quiescent individuals (which were even more crowded during nocturnal and spring low tides) occurred at every low tide and at approximately the same place. Size and sex composition of clumps differed from scattered samples, suggesting that the clustering habit is exclusive to crabs which either need to frequently change their shells (due to their faster growth rate) or are less efficient in the competition to acquire such resources. [ABSTRACT FROM PUBLISHER]

The activity rhythms of the swimming Portunid Thalamita crenata have been studied on the basis of crab sightings in surveys along three transects of a mangrove swamp in Kenya. Activity is well matched to the environmental regime and is prevalent during the high tides. However, activity does not occur over the whole of the high tide, but is confined to “temporal windows”; corresponding to a water level between 10 and 30 cm. Our findings suggest that activity in Thalamita crenata is shaped by the tidal cycles and we propose that variation in hydrostatic pressure as the tide changes is the cue which elicits activity. [ABSTRACT FROM PUBLISHER]

The spatial strategy of the hermit crab Clibanarius longitarsus was studied during a semilunar tidal cycle in a mangrove swamp in Kenya. This species is isospatial, being active at HW and taking refuge during its wrong phase (air) within the mangrove roots at LW. However, as revealed by radio‐telemetry, these animals (as well as other decapods) may miss one or more activity cycles. During their displacements, they followed a straight course parallel to the coast‐line but limited within a narrow and constant channel from the mangrove edge to the sea. Displacement was significantly higher at spring tides (with a maximum of 450 m), but there was no difference in extent between nocturnal and diurnal tides. Animals maintained the same locomotory sense during single HWs, and over subsequent HWs. These movement patterns were fast dispersal along the x‐axis, as revealed by both a low recovery rate of tagged animals and the trajectories followed by 12 radio‐tracked hermits. This nomadic behaviour may be explained as a means of intercepting spatially unforeseeable resources. Empty shells are a limiting factor in this habitat, and to periodically obtain new gastropod shells is fundamental for hermits (due to the animals’ growth or deterioration of old shells). Acquiring them from dead snails or conspecifics may have placed a fitness premium on this expensive spatial strategy. [ABSTRACT FROM PUBLISHER]

We explore the use of experts in arbitration proceedings by analysing public procurement contract disputes in Italy. Balancing cost with accuracy, participants to a contract select arbitration when speedy dispute resolution is valued highly. Alternative dispute resolution mechanisms tend to give appointed arbitrators discretion in how to proceed. Consequently, principal‐agent problems can arise. Using an inverse‐probability‐weighted approach, we show that the use of an expert causes a slowing down of the case resolution, without having an effect on the outcome of the dispute nor resolving uncertainty as measured by unanimous decisions by the panel of arbitrators. Conflict resolution mechanism designers should consider the alignment of incentives between the disputants and the service providers. [ABSTRACT FROM AUTHOR]

Arbitration, as an alternative to litigation for contract disputes, reduces costs and time. While it has frequently been thought of as a substitute to pretrial bargaining and litigation, in fact, parties may be able to reach a settlement privately while engaged in the arbitration process. Consequently, the institutional design may influence the bargaining. We develop a theoretical model of pre-arbitration bargaining that is able to identify the impact of the institutional features on its success. A detailed data set from arbitration proceedings in Italy is analyzed. The exogenous heterogeneity in the composition of the panel of arbitrators allows us to illustrate its effect on bargaining. We show that the number of arbitrators used interacts with their experience and independence to reduce uncertainty and facilitate settlement. [ABSTRACT FROM AUTHOR]

Many Indo-Pacific mangrove macroinvertebrates are herbivorous and heavily dependent on leaf litter. As a consequence, fallen leaves become a limiting factor and competition occurs among conspecifics and heterospecifics. Neosarmatium meinerti and Cardisoma carnifex are two of the most common herbivorous crabs of the landward mangrove belt in East Africa, often sharing an area and time of activity. This study used a series of field experiments to investigate their feeding habits when co-existing. The high density reached by both species led to overlapping of the individual feeding ranges: during the feeding excursions each crab inevitably encountered, and actively interacted with, other conspecifics and heterospecifics. Competition for food was high: N. meinerti lost approximately 50% of its leaves to theft by C. carnifex. Thus, approximately half of the leaves obtained by C. carnifex were stolen from a foraging N. meinerti. Considering the frequency of such thefts, C. carnifex may be regarded as a facultative kleptoparasitic species. This is the first time that a such strategy has been recorded for a crab species and for a vegetable resource. [ABSTRACT FROM AUTHOR]

Biological rhythms with lunar components are common in nature. In the sea, the moon's gravitational pull on earth is the principal cause of the tides, which normally reach maximum amplitudes every new and full moon. Many populations synchronize spawning to this time. Some choose either the new or the full moon, implying that moonlight is important; but one lunar phase usually has higher tides than the other, and many species select the phase with the higher tide to improve the offshore transport of their progeny. However, tidal dominance by one lunar phase is not constant; it switches between new and full moon every seven months. We tested the influence of this 14-month "syzygy inequality cycle" (SIC) on lunar synchrony by sampling 11 populations of intertidal crabs at two locations in East Africa for 21 months. Eight populations synchronized larval release with the SIC. Tidal cues were more important than moonlight in entraining the reproductive rhythm, although two populations synchronized spawning to the new moon. SIC synchrony increased with population shore level, because only the higher lunar tide permitted top- shore spawning. Top-shore species therefore have a restricted lunar choice. SIC synchrony could be common, given that it occurs in most marine environments. [ABSTRACT FROM AUTHOR]