Ant versus bird exclusion effects on the arthropod assemblage of an organic citrus grove

1. Predation‐exclusion experiments have highlighted that top‐down control is pervasive in terrestrial communities, but most of these experiments are simplistic in that they only excluded a single group of predators and the effect of removal was evaluated on a few species from the community. The main goal of our study was to experimentally establish the relative effects of ants and birds on the same arthropod assemblage of canopy trees. 2. We conducted 1‐year long manipulative experiments in an organic citrus grove intended to quantify the independent effects of bird and ant predators on the abundance of arthropods. Birds were excluded with plastic nets whereas ants were excluded with sticky barriers on the trunks. The sticky barrier also excluded other ground dwelling insects, like the European earwig Forficula auricularia L. 3. Both the exclusion of ants and birds affected the arthropod community of the citrus canopies, but the exclusion of ants was far more important than the exclusion of birds. Indeed, almost all groups of arthropods had higher abundance in ant‐excluded than in control trees, whereas only dermapterans were more abundant in bird‐excluded than in control trees. A more detailed analysis conducted on spiders also showed that the effect of ant exclusion was limited to a few families rather than being widespread over the entire diverse spectrum of spiders. 4. Our results suggest that the relative importance of vertebrate and invertebrate predators in regulating arthropod populations largely depends on the nature of the predator–prey system.     

Two closely linked tomato HKT coding genes are positional candidates for the major tomato QTL involved in Na+/K+ homeostasis

The location of major quantitative trait loci (QTL) contributing to stem and leaf [Na⁺] and [K⁺] was previously reported in chromosome 7 using two connected populations of recombinant inbred lines (RILs) of tomato. HKT1;1 and HKT1;2, two tomato Na⁺‐selective class I‐HKT transporters, were found to be closely linked, where the maximum logarithm of odds (LOD) score for these QTLs located. When a chromosome 7 linkage map based on 278 single‐nucleotide polymorphisms (SNPs) was used, the maximum LOD score position was only 35 kb from HKT1;1 and HKT1;2. Their expression patterns and phenotypic effects were further investigated in two near‐isogenic lines (NILs): 157‐14 (double homozygote for the cheesmaniae alleles) and 157‐17 (double homozygote for the lycopersicum alleles). The expression pattern for the HKT1;1 and HKT1;2 alleles was complex, possibly because of differences in their promoter sequences. High salinity had very little effect on root dry and fresh weight and consequently on the plant dry weight of NIL 157‐14 in comparison with 157‐17. A significant difference between NILs was also found for [K⁺] and the [Na⁺]/[K⁺] ratio in leaf and stem but not for [Na⁺] arising a disagreement with the corresponding RIL population. Their association with leaf [Na⁺] and salt tolerance in tomato is also discussed.     

An integrative taxonomic revision of the Tarentola geckos (Squamata,Phyllodactylidae) of the Cape Verde Islands

Recent phylogeographical analyses using mitochondrial DNA (mtDNA) sequences indicate that the Tarentola geckos from the Cape Verde archipelago originated from a propagule that dispersed from the Canary Islands approximately 7.7 Mya and that underwent a fast evolutionary radiation. Molecular analyses carried out to date clearly show some incongruences with the current taxonomy of Tarentola from the Cape Verde Islands, with some species being paraphyletic or polyphyletic, and several independently evolving lineages needing formal taxonomic recognition. The aim of this study was to clarify the systematics of this group to unravel its taxonomy by applying an integrative approach based on information from three independent sources: mtDNA, nuclear genes, and morphology. As a result of this taxonomic revision, two novel species for the islands of S. Nicolau and Fogo are described and eight subspecies are upgraded to species level. Moreover, an identification key for the genus Tarentola from the Cape Verde archipelago is presented. This study reconciles taxonomy and phylogeny in this group, provides a better understanding of diversity patterns, new insights on evolutionary hypotheses, and supports the basic framework for the future management and conservation of this unique reptile radiation. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 164 , 328–360.     

NEW SPECIES OF PARAPHIOMYS (RODENTIA, THRYONOMYIDAE) FROM THE LOWER MIOCENE OF AS-SARRAR, SAUDI ARABIA

Abstract:  The family Thryonomyidae is represented in the Lower Miocene of Saudi Arabia by a single species, Paraphiomys knolli sp. nov. This new taxon differs from all other thryonomyids in being small, lower molars having a short metalophulid II and an isolated anterolabial cuspid, and upper molars being antero-posteriorly compressed and pentalophodont. A cladistic analysis involving all extinct and extant species of thryonomyids is provided. Paraphiomys knolli branches as the sister-species of Paraphiomys pigotti , type species of the genus.     

Phylogeography of the marine isopod Stenosoma nadejda (Rezig, 1989) in North African Atlantic and western Mediterranean coasts reveals complex differentiation patterns and a new species

The transition zone between the Mediterranean and Atlantic basins has been extensively addressed in phylogeographical studies of marine species. However, biases exist towards the analysis of highly dispersive species, and there is a higher sampling effort in European coasts compared to North Africa. This may be hindering a detailed understanding of the historical and contemporary processes that shaped patterns of population genetic structure in the region. In the present study, we investigated the phylogeographical and phylogenetic patterns of mitochondrial cytochrome c oxidase subunit I sequences from a species with direct development and low dispersal abilities, Stenosoma nadejda (Rezig, 1989). The study area included 13 localities along the Atlantic and Mediterranean North African coasts, as well as the Alboran Sea. A new Stenosoma species, from the coasts of Algeria and Alboran Island, was discovered. For S. nadejda, phylogeographical analyses revealed three distinct clades: one in the Iberian Atlantic plus the Alboran Sea, one in the western Mediterranean, and another in the Atlantic coast of Africa. Haplotypes from the Alboran Island were more related to those from the western Mediterranean coast (east of the Almeria–Oran Front). Given the strong differentiation, it is probable that this species survived in multiple glacial refugia during the Pleistocenic glaciations. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104 , 419–431.     

Revealing the mechanisms of sexual isolation in a case of sympatric and parallel ecological divergence

Two ecotypes of a marine intertidal snail (Littorina saxatilis), living at different microhabitats and shore levels, have evolved in sympatry and in parallel across the Galician rocky shore. These ecotypes differ in many traits (including size) due to differential adaptation. They meet, mate assortatively, and partially hybridize at the mid shore where the two microhabitats overlap. The partial sexual isolation observed is claimed to be a side‐effect of the size differences between ecotypes combined with a size assortative mating found in most populations of this species. We investigated this hypothesis using three complementary experimental approaches. First, we investigated which of the different shell variables contributed most to the variation in individual sexual isolation in the field by using two new statistics developed for that purpose: (1) pair sexual isolation and (2) r_i, which is based on the Pearson correlation coefficient. We found that size is the most important trait explaining the sexual isolation and, in particular, the males appear to be the key sex contributing to sexual isolation. Second, we compared the size assortative mating between regions: exposed rocky shore populations from north‐westwern Spain (showing incomplete reproductive isolation due to size assortative mating) and protected Spanish and Swedish populations (showing size assortative mating but not reproductive isolation between ecomorphs). Most of the variation in size assortative mating between localities was significantly explained by the within‐population level of variation on size. Third, we performed a laboratory male choice experiment, which further suggested that the choice is made predominantly on the basis of size. These results confirm the mechanism proposed to explain the sexual isolation in the Galician hybrid zone and thus support this case as a putative example of parallel incipient speciation. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 94 , 513–526.     

Differentiation of innate but not learnt responses to host‐habitat odours contributes to rapid host finding in a parasitoid genotype

Abstract In parasitoids, host‐habitat odour can influence host searching within the habitat. This is the case in Leptopilina sp. (Hymenoptera, Figitidae), a Drosophila parasitoid searching for larvae by ovipositor probes. This a behaviour can be conditioned to fruit odours. In a previous study, the latency of probing to a fruit odour is reported to have a genetic variability within a laboratory strain. This suggests a link between rapidity of host discovery and fitness. In the present study, this hypothesis is tested by comparing responses to host‐habitat odours between two genotypes of Leptopilina heterotoma Thomson, from the Mediterranean coast (Antibes) and from Burgundy (Tailly). The two genotypes present contrasting rhythms and levels of locomotor activity linked to contrasting interspecific competition in their area of origin. The high activity observed in the Mediterranean genotype is interpreted as an adaptive response to a limited time‐window to win against a competitor species absent in Burgundy. The present study finds differentiation in innate but not learnt responses to host‐habitat odours. The more active genotype (Antibes) has a higher probability and a shorter latency of innate probing to the odours than the less active genotype (Tailly); Antibes females also find larvae and complete infestations more rapidly. Learning equalizes the probability and the latency of probing to the odours in both strains, and increases the probing duration. Innate responses to host‐habitat odours would allow time‐limited insects to increase their reproductive rate, when host predictability is high in the habitat. Selection of faster innate responses to host and habitat cues without evolution of learnt responses indicates that the initial host discovery is more crucial to fitness than subsequent ones.     

Haptoglobin and CCR2 receptor expression in ovarian cancer cells that were exposed to ascitic fluid: Exploring a new role of haptoglobin in the tumoral microenvironment

Haptoglobin (Hp) is an acute-phase protein that is produced by the liver to capture the iron that is present in the blood circulation, thus avoiding its accumulation in the blood. Moreover, Hp has been detected in a wide variety of tissues, in which it performs various functions. In addition, this protein is considered a potential biomarker in many diseases, such as cancer, including ovarian carcinoma; however, its participation in the cancerous processes has not yet been determined. The objective of this work was to demonstrate the expression of Hp and its receptor CCR2 in the ovarian cancer cells and its possible involvement in the process of cell migration through changes in the rearrangement of the actin cytoskeleton using western blot and wound-healing assays and confirming by confocal microscopy. Ovarian cancer cells express both Hp and its receptor CCR2 but only after exposure to ascitic fluid, inducing moderated cell migration. However, when the cells are exposed to exogenous Hp, the expression of CCR2 is induced together with drastic changes in the actin cytoskeleton rearrangement. At the same time, Hp induced cell migration in a much more efficient manner than did ascitic fluid. These effects were blocked when the CCR2 synthetic antagonist RS102895 was used to pretreat the cells. These results suggest that Hp-induced changes in the cell morphology, actin cytoskeleton structure, and migration ability of tumor cells, is possibly “preparing” these cells for the potential induction of the metastatic phenotype.