Biogeographical zonation of the western Iberian peninsula on the basis of the distribution of earthworm species

We used TWINSPAN and CANOCO to investigate the biogeography of the western Iberian Peninsula on the basis of the distribution of earthworms among ninety areas of Galicia, Portugal, Asturias, León, Zamora, Salamanca, Cáceres, Badajoz and Huelva. This part of Iberia is clearly divisible into a Eurosiberian Region in the north and west and a Mediterranean Region in the south and east. For earthworm faunas, however, the limit between these regions is considerably further south than is conventionally accepted on the basis of Rivas Martinez's (1987) vegetation-type classification. Species character- istic of the Eurosiberian Region include Dendrobaena madeirensis, D. octaedra, Allolobophora caliginosa and various species of the genus Lumbricus . Within this region the earthworm fauna of Asturias is clearly distinct from that of Galicia and northern Portugal. Species characteristic of the Mediterranean Region include Allolobophora caliginosa , A. chlorotica and A. rosea , but inventories from this region are most easily identified by the absence or scarcity of those species characteristic of the Eurosiberian Region. Many areas show intermediate characteristics between the two major regions, and in some cases one region 'intrudes' into the other.     

Freshwater molluscs of Yemen Arab Republic

A list is provided of the extant freshwater molluscan fauna of Yemen Arab Republic, based on collections made in wadis, brooks, and wells. A total of 12 freshwater snail species is recorded, some of which serve as intermediate hosts for Trematodes of the genera Schistosoma and Fasciola.     

Structure of Benthic Diatom Assemblages from a Mangrove Environment in a Mexican Subtropical Lagoon1

The taxonomic list and the structure of benthic diatom assemblages occurring in fine sediments (silt and sand) from the mangrove forest of the Balandra lagoon in Baja California Sur, Mexico was determined based on seasonal samplings for one year. Assemblage structure was analyzed using several ecological indices for estimating diversity (H'), dominance (REDI), equitability, and similarity. A total of 230 diatom taxa were identified and include 109 new records for the Baja California peninsula coast. Taxa representative of highly productive and hypersaline environments were common. Assemblages were characterized by a few abundant species and many uncommon or rare taxa. High diatom diversity estimates at all sampling sites during all seasons suggest that diatom assemblages in sediments of the Balandra lagoon represent a quasi-pristine environment.     

Climate increases regional tree-growth variability in Iberian pine forests

Tree populations located at the geographical distribution limit of the species may provide valuable information about tree‐growth response to changes on climatic conditions. We established nine Pinus nigra, 12 P. sylvestris and 17 P. uncinata tree‐ring width chronologies along the eastern and northern Iberian Peninsula, where these species are found at the edge of their natural range. Tree‐growth variability was analyzed using principal component analysis (PCA) for the period 1885–1992. Despite the diversity of species, habitats and climatic regimes, a common macroclimatic signal expressed by the first principal component (PC1) was found. Moreover, considering the PC1 scores as a regional chronology, significant relations were established with Spanish meteorological data. The shared variance held by the tree chronologies, the frequency of narrow rings and the interannual growth variability (sensitivity) increased markedly during the studied period. This shows an enhancement of growth synchrony among forests indicating that climate might have become more limiting to growth. Noticeably, an upward abrupt shift in common variability at the end of the first half of the 20th century was detected. On the other hand, moving‐interval response functions showed a change in the growth–climate relationships during the same period. The relationship between growth and late summer/autumn temperatures of the year before growth (August–September, negative correlation, and November, positive correlation) became stronger. Hence, water stress increase during late summer previous to tree growth could be linked to the larger growth synchrony among sites, suggesting that climate was driving the growth pattern changes. This agrees with the upward trend in temperature observed in these months. Moreover, the higher occurrence of extreme years and the sensitivity increase in the second half of the 20th century were in agreement with an increment in precipitation variability during the growing period. Precipitation variability was positively related to tree‐growth variability, but negatively to radial growth. In conclusion, a change in tree‐growth pattern and in the climatic response of the studied forests was detected since the mid‐20th century and linked to an increase in water stress. These temporal trends were in agreement with the observed increase in warmer conditions and in precipitation variability.     

Natural and human-mediated factors in the recovery and subsequent expansion of the Purple swamphen Porphyrio porphyrio L. (Rallidae) in the Iberian Peninsula

Instances of range contraction and population decline in bird species in Europe are more common than cases of recovery following decline. Here we report on the recovery and expansion processes of an endangered bird species in Europe, the purple swamphen (Porphyrio porphyrio L., Rallidae), with special reference to the Iberian Peninsula, its main distribution area in Western Europe. After a drastic decline during the first half of the 20th century, which restricted its range to a few areas in southern Spain, the Iberian population has recovered. Currently, the species occurs in a range similar to the one it had at the beginning of the 20th century, and has even colonized new areas. These processes seem to be the result of both human-mediated (effective protection of the species and suitable habitats; success of reintroduction programs as expansion focuses of birds colonizing nearby and distant regions [>300 km] wetlands) and natural factors (inter- and intra-seasonal cycles of wet and dry years). Thus, we found a significant relationship between rainfall and bird abundance and productivity, suggesting that such inter- and intra-seasonal cycles may have significant effects on demographic parameters that could be related to the expansion process. Finally the species shows remarkable adaptability, as proven by data on breeding success in recently colonized areas and the ability to breed shortly after reintroduction. We hypothesize that saturation of breeding habitats in established areas, a reasonable habitat continuity and favorable environmental conditions, and protection have facilitated the dispersion of birds.     

再论山东半岛和辽东半岛植物区系在区划中的地位

通过对山东半岛植物小区、辽东半岛植物小区、鲁中南低山丘陵植物小区和属于华北山地亚地区的北太行山_恒山植物小区属的相似性系数以及属的分布区类型的UPGMA分析, 结果表明 :山东半岛植物小区和鲁中南低山丘陵植物小区的相似性程度高, 关系近, 而辽东半岛植物小区与北太行山_恒山植物小区的相似性程度高, 关系近, 所以把山东半岛植物小区和辽东半岛植物小区划入同一个植物区系亚地区是不合理的, 建议把辽东半岛植物小区划归到华北山地亚地区, 原辽东、山东丘陵植物亚地区改名为山东丘陵植物亚地区。     

Food of introduced pumpkinseed sunfish: ontogenetic diet shift and seasonal variation

The pumpkinseed sunfish Lepomis gibbosus introduced into Lake Banyoles (Spain) were predominantly littoral but there was a tendency of large fish to use deeper zones. Their diet was dominated by littoral macrobenthos, particularly amphipods ( Echinogammarus sp.). There was ontogenetic variation in the diet, with small young-of-the-year (L_F<4 cm) feeding on several littoral microcrustaceans, especially the cladoceran Ceriodaphnia reticulata , whereas larger fish shifted to a freshwater shrimp ( Atyaephyra desmaresti ), snails and damselfly larvae. Seasonal variation in diet was linked to resource availability, with consumption of fish eggs and plant debris in spring and summer. In autumn, pumpkinseeds were partially zooplanktivores, preying on the cladoceran Daphnia longispina. The diet of pumpkinseeds in Lake Banyoles and other Iberian populations shows less molluscivory than North American populations. The potential ecological impact of this successful exotic species involves mainly predation on fish eggs and molluscs.     

Molecular phylogeography of the nose-horned viper (Vipera ammodytes, Linnaeus (1758)): evidence for high genetic diversity and multiple refugia in the Balkan peninsula

The nose-horned viper (Vipera ammodytes) occurs in a large part of the south-eastern Europe and Asia Minor. Phylogenetic relationships were reconstructed for a total of 59 specimens using sequences from three mitochondrial regions (16S and cytochrome b genes, and control region, totalling 2308 bp). A considerable number of clades were observed within this species, showing a large genetic diversity within the Balkan peninsula. Splitting of the basal clades was evaluated to about 4 million years ago. Genetic results are in contradiction with presently accepted taxonomy based on morphological characters: V. a. gregorwallneri and V. a. ruffoi do not display any genetic difference compared with the nominotypic subspecies (V. a. ammodytes), involving that these subspecies can be regarded as synonyms. High genetic divergence in the central part of the Balkan peninsula is not concordant with low morphological differentiation. Finally, the extensive genetic diversity within the Balkan peninsula and the colonisation routes are discussed.     

Genetic structure analysis of natural <Emphasis Type="Italic">Sargassum muticum</Emphasis> (Fucales,Phaeophyta) populations using RAPD and ISSR markers

Sargassum muticum is important in maintaining the structure and function of littoral ecosystems, and is used in aquaculture and alginate production, however, little is known about its population genetic attributes. In this study, random amplified polymorphic DNA (RAPD) and inter-simple sequence repeat (ISSR) markers were used to investigate the genetic structure of four populations of S. muticum and one outgroup of S. fusiforme (Harv.) Setchell from Shandong peninsula of China. The selected 24 RAPD primers and 19 ISSR primers amplified 164 loci and 122 loci, respectively. Estimates of genetic diversity with different indicators (P%, percentage of polymorphic loci; H, the expected heterozygosity; I, Shannon’s information index) revealed low or moderate level of genetic variations within each S. muticum population, and a high level of genetic differentiations were determined with pairwise unbiased genetic distance (D) and fixation index (F _ST ) among the populations. The Mantel test showed that two types of matrices of D and F _ST were highly correlated whether from RAPD (r = 0.9706, P = 0.009) or ISSR data (r = 0.9161, P = 0.009). Analysis of molecular variance (AMOVA) was conducted to apportion the variations among and within the S. muticum populations. It indicated that variations among populations were higher than those within populations, being 55.82% verse 44.18% by RAPD and 55.21% verse 44.79% by ISSR, respectively. Furthermore, the Mantel test suggested that genetic differentiations among populations were related to the geographical distances (r > 0.6), namely, conformed to the IBD (isolation by distance) model, as expected from UPGMA (unweighted pair group method with arithmetic averages) cluster analysis. On the whole, the high genetic structuring among the four S. muticum populations along the distant locations was clearly indicated in RAPD and ISSR analyses (r > 0.9, P < 0.05) in our study.     

Population genetic structure and diversity of the Apennine endemic stream frog, Rana italica--insights on the Pleistocene evolutionary history of the Italian peninsular biota

For most species in the Western Palaearctic region, southern Mediterranean peninsulas have been identified as major Quaternary refugia and hotspots of intraspecific diversity, and thus, as areas of particular relevance for the conservation of the evolutionary potential. We analysed the patterns of geographical variation among 26 populations of the Italian stream frog, using both nuclear (allozymes) and mitochondrial (partial cytochrome b sequences) markers. Phylogenetic, phylogeographical and population genetic analyses suggested that the species survived the last glacial–interglacial cycles in two distinct refugia, one restricted to the tip of the Calabrian peninsula, at the extreme south of the species' range, the other spanning from central Calabria to central Apennines and showing evidences for further population subdivision therein. Historical demographic tests suggested a significant population expansion from the latter, which most likely began around the last pleniglacial. This expansion would have led to the rapid colonization of the northern Apennines to the north, and to a secondary contact and population admixture with the population from the southern refugium in southern central Calabria. A comparison of the evolutionary history inferred for the Italian stream frog with the data emerging for other codistributed species suggests: (i) the generality of a multiple-refugia scenario for the Italian peninsula, (ii) the possible occurrence of at least one suture zone in southern Italy, and (iii) that for most species, this Pleistocene refugium is not only a hotspot, but also a melting pot of intraspecific genetic diversity. Finally, the conservation implications of these results are also briefly highlighted.