The influence of the Benguela upwelling system on Namibia's marine biodiversity

Namibia's marine environment falls within the Benguela system, an eastern boundary current upwelling system in the south eastern Atlantic Ocean. Conditions within much of this environment change continuously as a consequence of the upwelling of nutrient-rich water into the surface zone. In addition, irregular anomalies in temperature, oxygen concentration and salinity occur, particularly in shelf waters. These fluctuations, which are inherent in the functioning of the Benguela system, tend to favour the persistence of few, generalist species, while at the same time high productivity supports large abundances. This trend is evident in all the major marine habitats off Namibia, where diversity is often lower than in comparable habitats in the southern Benguela system off the west coast of South Africa. Namibia's marine environment is considered 'relatively pristine', although threats to biodiversity are posed by both natural and anthropogenic phenomena.     

Biogeography of common dolphins (genus Delphinus) in the Southwestern Atlantic Ocean

• 1 The common dolphins (genus Delphinus) have one of most problematic taxonomies and complex distribution patterns of all cetaceans. Although the taxonomy and the distribution seem to have been clarified somewhat in the eastern North Pacific and Indo‐Pacific Oceans, many questions remain in the Southwestern Atlantic Ocean (SWA). We review the biogeography of Delphinus in the SWA.
• 2 We reviewed data from strandings, incidental catches and sightings since 1922. Systematic surveys were conducted in five major areas. Twenty‐one natural history collections were examined, and 135 skulls were measured.
• 3 A total of 184 records of common dolphins were compiled. Delphinus apparently occurs in three stocks in the SWA: one located in northern Brazil and two from southeastern Brazil (～22°S) to central Argentina (～42°S). Two distinct patterns in habitat use were observed by depth: in southeastern Brazil, sightings were restricted to coastal waters with water depths ranging from 18m to 70m. On the other hand, in the area that extends from southern Brazil to Central Argentina (from 28°S to 42°S), sightings were recorded in deeper waters, ranging from 71m to 1435m, with the exception of occasional coastal sightings. The cranial analyses demonstrated that both short‐beaked common dolphins Delphinus delphis and long‐beaked common dolphins Dephinus capensis occur in the SWA.
• 4 In the SWA, Delphinus seems to occur near areas of high productivity. One stock is associated with the productive waters discharged by the Amazon River and possibily with the coastal upwelling system off the coast of Venezuela, while the other stocks are associated with the Cabo Frio upwelling system and the Subtropical Convergence. Our results indicate that the current taxonomy does not adequately reflect the amount of variation within the genus in the world.

     

Genetic variation and population subdivision of the endangered Iberian cyprinid Chondrostoma lusitanicum

Products of 24 presumptive enzyme loci were used to analyse the consequences on genetic structure and variation of the Chondrostoma lusitanicum population decline within the Tejo basin. This rare cyprinid is endemic to the Iberian Peninsula and has a very restricted distribution. Five samples from the Tejo catchment were compared with a sample from a small basin, the Samarra, that has not suffered obvious anthropogenic pressures and where the fish is still abundant. Heterozygosity and polymorphism were higher overall in the Samarra. Several lines of evidence indicate a high degree of population subdivision within the Tejo basin. In fact, about half of the total gene diversity detected in the Tejo population was due to differences among samples. This differentiation appeared to be caused by genetic drift and possibly differential local selection, coupled with reduced gene flow among localities. The accelerated process of habitat degradation occurring in the lowland streams of the Tejo basin will lead to the inevitable reduction of intraspecies genetic diversity.     

Effect of Temperature on Germination in Northernmost Populations of Culcita macrocarpa and Woodwardia radicans

Abstract: Spore germination of Culcita macrocarpa C. Presl and Woodwardia radicans (L.) Sm. from nine populations at the northern limit of their distribution, in the northwest Iberian Peninsula, was investigated. In a first experiment, population type and temperature (10, 15, 20, and 25 °C) were both found to affect germination percentage and germination time significantly in both species. There were also significant interactions between the two factors with respect to the percentage germination of C. macrocarpa and the germination time of W. radicans. In C. macrocarpa there was an outstanding increase in germination time at 15 °C and, above all, at 10 °C, whereas in W. radicans the most remarkable result was the existence of two populations with especially low germination percentages. In a second experiment, germination of 20 individuals from each population of W. radicans was compared with similar inter-population differentiation. Although its variability possibly has a genetic basis, these species are able to germinate successfully, and it seems probable that the season in which it occurs depends more on spore release than on thermal conditions in the populations. The effect of temperature on germination in both species does not explain their coastal distribution. Temperature is probably more important in limiting other stages of the life cycle.     

Infraspecific variation and phylogeography of the high-polyploid Iberian endemic Anthoxanthum amarum Brot. (Poaceae; Pooideae) assessed by random amplified polymorphic DNA markers (RAPDs) and morphology

High morphological and ecological diversity has been observed in the north-west Iberian Peninsula endemic Anthoxanthum amarum Brot., for which two different morphotypes (northern and southern) have been described on the basis of qualitative traits and geographical origin. In the present study, a combined molecular and morphological method was applied to ten populations of this species with the following aims: (1) to assess whether the variation observed was taxonomically meaningful; (2) to assess the influence of the environment on the variation in the morphological characters; and (3) to track the potential phylogeographical information deduced from our random amplified polymorphic DNA marker (RAPD) data in order to draw inferences about the past history of this species in the north-west Iberian Peninsula. To achieve these aims, 26 macromorphological characters were recorded in 279 specimens, and 77 RAPD phenotypes were identified in the 79 plants studied. The association analyses performed using the morphological and molecular data showed that no clear separation existed between the morphs, and a strong correlation between qualitative characters and the environment was detected. Moreover, both the multivariate analyses and the assignment test based on RAPD data revealed that the genetic variation was hierarchically structured, and three genetically distinct groups could be identified. Two of these clusters might correspond to different expansion routes proposed in the literature for different plant species in the north-west Iberian Peninsula.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 155 , 179–192.     

Population genetic structure and hybridization patterns in the Mediterranean endemics Phlomis lychnitis and P. crinita (Lamiaceae)

BACKGROUND AND AIMS: The historical influence of gene flow and genetic drift after the last glacial phase of the Quaternary Period is reflected in current levels of genetic diversity and population structure of plant species. Moreover, hybridization after secondary contact might also affect population genetic diversity and structure. An assessment was made of the genetic variation and hybrid zone structure in Iberian populations of the Mediterranean Phlomis lychnitis and P. crinita, for which phylogenetic relationships are controversial, and hybridization and introgression are common. METHODS: Allozyme variation at 13 loci was analysed in 1723 individual plants sampled from 35 natural locations of P. lychnitis, P. crinita subsp. malacitana and P. crinita subsp. crinita in southern and eastern Spain. Standard genetic diversity parameters were calculated and patterns of genetic structure in each taxon were tested to fit the equilibrium between gene flow and genetic drift. Individual multilocus genotypes were subjected to Bayesian clustering analysis to estimate hybridization and introgression rates for both geographic regions. KEY RESULTS: Contrasting patterns in the distribution of genetic variation among the three taxa were found. Phlomis lychnitis showed no significant inbreeding, low genetic differentiation among populations and no evidence of isolation by distance. Phlomis crinita subsp. malacitana and P. crinita subsp. crinita showed high levels of genetic structure consistent with a pattern of gene flow-drift equilibrium. Higher instances of hybridization and introgression were detected in locations from southern Spain compared with locations from eastern Spain, matching unimodal and bimodal hybrid zones, respectively. CONCLUSIONS: High instances of historical gene flow, range expansion and altitudinal movement during the Quaternary Period, and lineage sorting can explain the diversity of patterns observed. The results suggest that P. lychnitis is the most differentiated lineage in the group; however, the relationship between the three taxa remains unclear.     

Identifying bipolar knapping in the Mesolithic site of Font del Ros (northeast Iberia)

Despite recent advances in the identification of bipolar knapping, its role in many sites is not well known. We propose to assess the significance of this technique in the context of changes that occur in the Mesolithic. A lithic assemblage was recovered from unit SG at Font del Ros (Catalunya, Spain) in which pitted stones, cores and products arising from bipolar reduction (flakes, fragments and splintered pieces) were identified. This study indicates that the bipolar technique is fundamental in the settlement. These results are key to defining the organization of Holocene hunter-gatherer subsistence in northeast Iberia.     

Atlas of Iberian water beetles (ESACIB database)

The ESACIB (‘EScarabajos ACuáticos IBéricos’) database is provided, including all available distributional data of Iberian and Balearic water beetles from the literature up to 2013, as well as from museum and private collections, PhD theses, and other unpublished sources. The database contains 62,015 records with associated geographic data (10×10 km UTM squares) for 488 species and subspecies of water beetles, 120 of them endemic to the Iberian Peninsula and eight to the Balearic Islands. This database was used for the elaboration of the “Atlas de los Coleópteros Acuáticos de España Peninsular”. In this dataset data of 15 additional species has been added: 11 that occur in the Balearic Islands or mainland Portugal but not in peninsular Spain and an other four with mainly terrestrial habits within the genus Helophorus (for taxonomic coherence). The complete dataset is provided in Darwin Core Archive format.     

Genetic evidence for multiple events of hybridization between wolves and domestic dogs in the Iberian Peninsula

Hybridization between wild species and their domestic counterparts may represent a major threat to natural populations. However, high genetic similarity between the hybridizing taxa makes the detection of hybrids a difficult task and may hinder attempts to assess the impact of hybridization in conservation biology. In this work, we used a combination of 42 autosomal microsatellites together with Y-chromosome microsatellite-defined haplotypes and mtDNA sequences to investigate the occurrence and dynamics of wolf-dog hybridization in the Iberian Peninsula. To do this, we applied a variety of Bayesian analyses and a parallel set of simulation studies to evaluate (i) the differences between Iberian wolves and dogs, (ii) the frequency and geographical distribution of hybridization and (iii) the directionality of hybridization. First, we show that Iberian wolves and dogs form two well-differentiated genetic entities, suggesting that introgressive hybridization is not a widespread phenomenon shaping both gene pools. Second, we found evidence for the existence of hybridization that is apparently restricted to more peripheral and recently expanded wolf populations. Third, we describe compelling evidence suggesting that the dynamics of hybridization in wolf populations is mediated by crosses between male dogs and female wolves. More importantly, the observation of a population showing the occurrence of a continuum of hybrid classes forming mixed packs may indicate that we have underestimated hybridization. If future studies confirm this pattern, then an intriguing avenue of research is to investigate how introgression from free-ranging domestic dogs is enabling wolf populations to adapt to the highly humanized habitats of southern Europe while still maintaining their genetic differentiation.