Phylogeography and regional endemism of a passively dispersing zooplankter: mitochondrial DNA variation in rotifer resting egg banks.

We investigated the phylogeography of the salt water rotifer Brachionus plicatilis, a cyclical parthenogen with passive dispersal mechanisms, using resting eggs recovered from saline lake sediments. Individual resting eggs were obtained from a large selection of lakes which were representative of five endorheic basins and the chain of coastal ponds in the Iberian Peninsula. The novel use of resting eggs allows the integration of seasonal and annual variations as well as the impact of stochastic effects such as drift and local extinction. A 653 bp fragment of the mitochondrial cytochrome oxidase subunit I (COI) gene was sequenced from 98 eggs. Our results revealed a deep phylogeographical structure in this species, with a division into two main lineages with distinct geographical distributions, which probably diverged at the beginning of the Pleistocene period. Most of the mitochondrial DNA haplotypes were restricted to single lakes. Nested clade analysis supported Early Pleistocene fragmentation of populations, low gene flow and some long-distance colonization. These conclusions contrast strongly with previous ideas on rotifer biogeography and this pattern is consistent with a recolonization of the Iberian Peninsula from two glacial refugia. The results provide new insights into the processes responsible for the genetic diversification of passive dispersers, a life-history trait typical of zooplanktonic biotas.     

Widespread secondary contact and new glacial refugia in the halophilic rotifer Brachionus plicatilis in the Iberian Peninsula

Small aquatic organisms harbour deep phylogeographic patterns and highly structured populations even at local scales. These patterns indicate restricted gene flow, despite these organisms' high dispersal abilities, and have been explained by a combination of (1) strong founder effects due to rapidly growing populations and very large population sizes, and (2) the development of diapausing egg banks and local adaptation, resulting in low effective gene flow, what is known as the Monopolization hypothesis. In this study, we build up on our understanding of the mitochondrial phylogeography of the halophilic rotifer Brachionus plicatilis in the Iberian Peninsula by both increasing the number of sampled ponds in areas where secondary contact is likely and doubling sample sizes. We analyzed partial mitochondrial sequences of 252 individuals. We found two deep mitochondrial DNA lineages differing in both their genetic diversity and the complexity of their phylogeographic structure. Our analyses suggest that several events of secondary contact between clades occurred after their expansion from glacial refugia. We found a pattern of isolation-by-distance, which we interpret as being the result of historical colonization events. We propose the existence of at least one glacial refugium in the SE of the Iberian Peninsula. Our findings challenge predictions of the Monopolization hypothesis, since coexistence (i.e., secondary contact) of divergent lineages in some ponds in the Iberian Peninsula is common. Our results indicate that phylogeographic structures in small organisms can be very complex and that gene flow between diverse lineages after population establishment can indeed occur.     

Speciation in ancient cryptic species complexes: evidence from the molecular phylogeny of Brachionus plicatilis (Rotifera)

Continental lake-dwelling zooplanktonic organisms have long been considered cosmopolitan species with little geographic variation in spite of the isolation of their habitats. Evidence of morphological cohesiveness and high dispersal capabilities support this interpretation. However, this view has been challenged recently as many such species have been shown either to comprise cryptic species complexes or to exhibit marked population genetic differentiation and strong phylogeographic structuring at a regional scale. Here we investigate the molecular phylogeny of the cosmopolitan passively dispersing rotifer Brachionus plicatilis (Rotifera: Monogononta) species complex using nucleotide sequence variation from both nuclear (ribosomal internal transcribed spacer 1, ITS1) and mitochondrial (cytochrome c oxidase subunit I, COI) genes. Analysis of rotifer resting eggs from 27 salt lakes in the Iberian Peninsula plus lakes from four continents revealed nine genetically divergent lineages. The high level of sequence divergence, absence of hybridization, and extensive sympatry observed support the specific status of these lineages. Sequence divergence estimates indicate that the B. plicatilis complex began diversifying many millions of years ago, yet has showed relatively high levels of morphological stasis. We discuss these results in relation to the ecology and genetics of aquatic invertebrates possessing dispersive resting propagules and address the apparent contradiction between zooplanktonic population structure and their morphological stasis.     

Long-term coexistence of rotifer cryptic species

Despite their high morphological similarity, cryptic species often coexist in aquatic habitats presenting a challenge in the framework of niche differentiation theory and coexistence mechanisms. Here we use a rotifer species complex inhabiting highly unpredictable and fluctuating salt lakes to gain insights into the mechanisms involved in stable coexistence in cryptic species. We combined molecular barcoding surveys of planktonic populations and paleogenetic analysis of diapausing eggs to reconstruct the current and historical coexistence dynamics of two highly morphologically similar rotifer species, B. plicatilis and B. manjavacas. In addition, we carried out laboratory experiments using clones isolated from eight lakes where both species coexist to explore their clonal growth responses to salinity, a challenging, highly variable and unpredictable condition in Mediterranean salt lakes. We show that both species have co-occurred in a stable way in one lake, with population fluctuations in which no species was permanently excluded. The seasonal occurrence patterns of the plankton in two lakes agree with laboratory experiments showing that both species differ in their optimal salinity. These results suggest that stable species coexistence is mediated by differential responses to salinity and its fluctuating regime. We discuss the role of fluctuating salinity and a persistent diapausing egg banks as a mechanism for species coexistence in accordance with the 'storage effect'.     

Phylogeographical and speciation patterns in subterranean worm lizards of the genus Blanus (Amphisbaenia: Blanidae)

The peculiar lifestyle of subterranean reptiles must determine their modes of speciation and diversification. To further understand the evolutionary biology of subterranean reptiles, we studied the phylogeny of worm lizards of the genus Blanus and the phylogeography of its Iberian representatives. We used mitochondrial (ND4 and 16S rRNA) and nuclear (anonymous) partial gene sequences to resolve phylogenetic relationships within Blanus. The Eastern Mediterranean Blanus strauchi was recovered as sister group of Western Mediterranean species. Iberian and North African Blanus were recovered as reciprocally monophyletic groups. The same genes were used to determine phylogeography of 47 populations of Blanus cinereus. Mitochondrial and nuclear sequence data recovered two highly supported Iberian clades. Parapatry and high sequence divergences between them suggest that these clades may represent independent taxonomic units. A molecular clock was calibrated considering that the split between Iberian and North African Blanus was due to the re-opening of the Betic Strait in the Upper Tortonian (8-9 million years ago). Differentiation between the two Iberian clades was estimated to date back to 5.2 million years ago. The Central Iberian clade included five mitochondrial haplotype lineages (A-E). Geographical ranges of two of them broadly overlap in the central Iberian plateau. After testing alternative hypotheses, the most likely explanation for this striking phylogeographical pattern involves recent dispersal of one of the lineages (C) over the geographical range of the other (B). The inferred recent dispersal of this fossorial reptile is explained in terms of demographic advantages associated to underground lifestyle.     

Genetic differentiation and phylogeographical structure of the Brachionus calyciflorus complex in eastern China

Spatio-temporal patterns and processes of genetic differentiation in passively dispersing zooplankton are drawing much attention from both ecologists and evolutionary biologists. Two opposite phylogeographical scenarios have already been demonstrated in rotifers, which consist of high levels of genetic differentiation among populations even on small geographical scales on the one hand and the traditionally known cosmopolitanism that is associated with high levels of gene flow and long-distance dispersal via diapausing stages on the other hand. Here, we analysed the population genetic structure and the phylogeography of the Brachionus calyciflorus species complex in eastern China. By screening a total of 318 individuals from ten locations along a 2320-km gradient and analysing samples from two growing seasons, we aimed at focusing on both small- and large-scale patterns. We identified eight cryptic species and verified species status of two of these by sexual reproduction tests. Samples in summer and winter yielded different cryptic species. The distribution patterns of these genetically distinct cryptic species were diverse across eastern China, from full cosmopolitanism to local endemism. The two most abundant cryptic species BcWIII and BcSW showed a pattern of strong genetic differentiation among populations and no significant isolation by distance. Long-distance colonization, secondary contact and recent range expansion are probably responsible for the indistinct pattern of isolation by distance. Our results suggest that geographical distance is more important than temporal segregation across seasons in explaining population differentiation and the occurrence of cryptic species. We explain the current phylogeographical structure in the B. calyciflorus species complex by a combination of recent population expansion, restricted gene flow, priority effects and long-distance colonization.     

Phylogeny of slug species of the genus Arion: evidence of monophyly of Iberian endemics and of the existence of relict species in Pyrenean refuges

The Iberian Peninsula contains the majority of the Paleartic land slug species of the genus Arion, which exhibits diverse taxonomic problems. The present study investigated Arion taxonomy on the basis of analyses of the mitochondrial ND1 gene and nuclear internal transcribed spacer 1 (ITS1) sequences. The Iberian endemic species were monophyletically clustered in two divergent sister clades. The topotype specimens of Arion lusitanicus and the closely related species Arion nobrei and Arion fuligineus, as well as Arion hispanicus and Arion flagellus, were grouped into an ‘Atlantic’ clade, whereas Arion baeticus, Arion gilvus, Arion anguloi, Arion wiktori and Arion paularensis were included in a ‘Continental–Mediterranean’ clade. Calibration of mutation rate in the ND1 gene suggested that the divergence of these two clades occurred around the Pliocene–Pleistocene boundary, with subsequent speciation events during the Pleistocene. A group of ancestral and divergent endemic species with distribution centred in the Pyrenean mountain range (Arion molinae, Arion lizarrusti, Arion antrhacius and Arion iratii) arose in the Pliocene and survived through the Pleistocene in geographically confined small populations. Arion lusitanicus showed up to be polyphyletic: specimens, sampled outside the geographic range of the topotype in the north‐western Iberian Peninsula, were included in a non‐monophyletic clade together with the widely distributed species Arion ater and Arion rufus. The divergent species with a wide European distribution (Arion subfuscus, Arion hortensis, Arion fagophilus and Arion intermedius) were located in basal positions in all topologies. The evolutionary history of these slug species (highly sensitive to climatic factors, with capacity for both outcrossing and selfing, and with low dispersal ability) appears to have been moulded by Pliocene–Pleistocene climate events and by the rugged topography of southern Europe, giving rise to repeated cycles of population isolation during periods of glaciation alternating with interglacial expansions limited by geographic barriers.     

The interplay between colonization history and gene flow in passively dispersing zooplankton: microsatellite analysis of rotifer resting egg banks

Zooplanktonic organisms that disperse passively as diapausing eggs often exhibit surprisingly strong population subdivision given their high colonization ability. Here we attempt to disentangle the impacts of colonization history and gene flow on these organisms by studying the population genetic structure of the rotifer Brachionus plicatilis. The resting egg banks of B. plicatilis in fourteen salt lake populations in the Iberian Peninsula were examined using seven microsatellite loci. A remarkably high degree of geographical structuring was found (F_st=0.43), with a significant pattern of isolation by distance. Microsatellite loci were in genetic equilibrium, ruling out inbreeding as an important force in population structuring. Comparisons are drawn with previously published phylogeographical data. Surprisingly, introgression of nuclear genes was detected in neighbouring populations with divergent mtDNA haplotypes. These results stress the long lasting impact of colonization history and the modulating effect of gene flow at local scales in these organisms.     

Phylogeography of a habitat specialist with high dispersal capability: the Savi's Warbler Locustella luscinioides

In order to describe the influence of Pleistocene glaciations on the genetic structure and demography of a highly mobile, but specialized, passerine, the Savi's Warbler (Locustella luscinioides), mitochondrial DNA sequences (ND2) and microsatellites were analysed in c.330 individuals of 17 breeding and two wintering populations. Phylogenetic, population genetics and coalescent methods were used to describe the genetic structure, determine the timing of the major splits and model the demography of populations. Savi's Warblers split from its sister species c.8 million years ago and have two major haplotype groups that diverged in the early/middle Pleistocene. One of these clades originated in the Balkans and is currently widespread, showing strong evidence for population expansion; whereas the other is restricted to Iberia and remained stable. Microsatellites agreed with a genetic break around the Pyrenees, but showed considerable introgression and a weaker genetic structure. Both genetic markers showed an isolation-by-distance pattern associated with the population expansion of the eastern clade. Breeding populations seem to be segregated at the wintering sites, but results on migratory connectivity are preliminary. Savi's Warbler is the only known migratory bird species in which Iberian birds did not expand beyond the Pyrenees after the last glaciation. Despite the long period of independent evolution of western and eastern populations, complete introgression occurred when these groups met in Iberia. Mitochondrial sequences indicated the existence of refugia-within-refugia in the Iberian Peninsula during the last glacial period, which is surprising given the high dispersal capacity of this species. Plumage differences of eastern subspecies seemed to have evolved recently through natural selection, in agreement with the glacial expansion hypothesis. This study supports the great importance of the Iberian Peninsula and its role for the conservation of genetic variation.     

Cryptic diversity of Italian bats and the role of the Apennine refugium in the phylogeography of the western Palaearctic

The Mediterranean Basin is typified by a high degree of species rarity and endemicity that reflects its position, geomorphology, and history. Although the composition and cryptic variation of the bat faunas from the Iberian and Balkan Peninsulas are relatively well studied, data from the Apennine Peninsula are still incomplete. This is a significant shortfall, given the presumed refugial role of this region in the context of Europe's Pleistocene phylogeography. It was thus our aim to supplement the phylogeographical information from the region, generating mitochondrial sequences and reviewing published data, with a focus on the dispersal and diversification patterns characterizing taxa with different life strategies. Site‐specific lineages were ascertained, especially in the genera Myotis and Plecotus and amongst the pipistrelloid bats, representing speciose radiations. It was possible to observe disjunct ranges with patches isolated south of the Alps in several species, corresponding with evolution of elevated genetic distance. The genetic subdivision within the continuous Italian range into northern and southern lineages in several taxa indicated the possible past substructure of the refugium. Several shared lineages between the Apennine and Ibero‐Maghrebian regions were observed, indicating connectivity between the Adriatic and Atlantic?Mediterranean refuges, and raising questions as to which region these clades originated from and what was the direction of faunal exchange between them. In contrast to Europe's other two main refugia, the Apennine Peninsula is a smaller region with simpler phylogeographical patterns. Nevertheless, our results support the idea that the region generated novel lineages. Whereas diversification in sedentary bats may have been driven through the generation of in situ adaptations, specialization, and niche differentiation, the emergence of species with a tramp strategy could have entailed the utilization of faunal drift and the taxon cycle. © 2015 The Linnean Society of London     

Evolutionary and biogeographical patterns within Iberian populations of the genus Squalius inferred from molecular data

Origins and biogeography of the chub, genus Squalius (formerly within the genus Leuciscus), in the Iberian Peninsula were inferred from comparison between patterns of geographic distribution and phylogenetic relationships among populations belonging to 14 European Squalius species. The phylogeny recovered was based on the complete sequence of the mitochondrial cytochrome b gene. Squalius species were grouped into three major clades. The basal clade included species distributed across the ancient Paratethys Sea. The second clade included species from Central and East Europe and the northern areas of the Mediterranean basin towards Minor Asia. The third clade included species from the Mediterranean Peninsulas (Iberian, Italy, and Balkans). The Iberian Squalius species do not constitutes a monophyletic group. Our data indicate that the Iberian Peninsula was colonized at least twice by two different monophyletic lineages, a meridional group and a Central Europe group. The amount of species diversity found in the Iberian Peninsula and the phylogenetic relationships among these species, together with their geographic distribution, suggest that the Central Europe lineage colonized the Iberian Peninsula at a latter time. Our data indicate that the northeastern Iberian lineage is phylogenetically close to Greek populations of Squalius cephalus, while the second lineage formed a monophyletic group including Squalius pyrenaicus, Squalius carolitertii, Squalius aradensis, and Squalius torgalensis. The speciation process that generated these species and the geographic structure of their populations, principally in S. pyrenaicus, can be attributed to paleogeographical events like the ancient endorrheism and the development of hydrographic basins.     

Species status and phylogeography of two closely related Coptolabrus species (Coleoptera: Carabidae) in South Korea inferred from mitochondrial and nuclear gene sequences

We investigated the species status and intraspecific phylogeography in South Korea of two ground beetle species, Coptolabrus jankowskii and Coptolabrus smaragdinus (Coleoptera: Carabidae), using statistical parsimony networks and nested clade analyses based on sequences from the mitochondrial cytochrome oxidase subunit I (COI) and nuclear phosphoenolpyruvate carboxykinase (PepCK) and wingless (Wg) genes. Although traditional parsimony tree construction generally failed to resolve interspecific relationships and construct biologically meaningful genealogies, analysis using statistical parsimony networks yielded statistically significant inter- and intraspecific genealogical structures. We found that although these two species represent a notable case of trans-species polymorphisms in both mitochondrial and nuclear gene sequences, their status as separate species was evidenced by the nonrandom association between species and nested clades at various nesting levels. The exceptional occurrence of shared identical or very similar COI sequences was considered to be the result of introgressive hybridization. In addition, range expansion and fragmentation events across the Korean Peninsula and adjacent islands were inferred from nested clade phylogeographical analyses. The COI gene revealed the geographical divergence of major eastern and western clades and historical biogeographical events within each major clade, whereas the nuclear PepCK gene, which did not reveal corresponding east-west clades, indicated past fragmentation and range expansion across wide areas that may have been the result of older biogeographical events. Thus, phylogeographical inferences drawn from analyses of mitochondrial and nuclear genes can reveal different and potentially complementary information about phylogeographical processes.     

Evidence for the persistence of the land planarian species Microplana terrestris (Müller, 1774) (Platyhelminthes, Tricladida) in microrefugia during the Last Glacial Maximum in the northern section of the Iberian Peninsula

The land planarian species Microplana terrestris (Müller, 1774), shows a wide distribution in the north of the Iberian Peninsula, where mature humid forests can be found. Since most terrestrial planarians require the presence and good condition of wet forests to survive, a parallel evolution of the taxon and its habitat might be expected. Performing molecular analyses (mitochondrial cytochrome oxidase I and nuclear ITS-1 genes) we estimated the demography and biogeographic history of the species in that region. Our results show the species to present levels of genetic diversity likely originating before the Pleistocene. However, it presents a genetic structure that presumably resulted from its survival in various refugees during the Pleistocene glacial cycles. The two main genetic groups, present on the Iberian Peninsula, seem to have different origins: the western one being of Iberian origin, while the eastern group may have been the result of a re-colonization from the north. In both cases, their biogeographical history mirrors their habitat range movements, reinforcing the phylogeographical hypothesis put forward for its preferred habitat, i.e. humid forests.     

Impact of mountain chains, sea straits and peripheral populations on genetic and taxonomic structure of a freshwater turtle, Mauremys leprosa (Reptilia, Testudines, Geoemydidae)

Mauremys leprosa, distributed in Iberia and North‐west Africa, contains two major clades of mtDNA haplotypes. Clade A occurs in Portugal, Spain and Morocco north of the Atlas Mountains. Clade B occurs south of the Atlas Mountains in Morocco and north of the Atlas Mountains in eastern Algeria and Tunisia. However, we recorded a single individual containing a clade B haplotype in Morocco from north of the Atlas Mountains. This could indicate gene flow between both clades. The phylogenetically most distinct clade A haplotypes are confined to Morocco, suggesting both clades originated in North Africa. Extensive diversity within clade A in south‐western Iberia argues for a glacial refuge located there. Other regions of the Iberian Peninsula, displaying distinctly lower haplotype diversities, were recolonized from within south‐western Iberia. Most populations in Portugal, Spain and northern Morocco contain the most common clade A haplotype, indicating dispersal from the south‐western Iberian refuge, gene flow across the Strait of Gibraltar, and reinvasion of Morocco by terrapins originating in south‐western Iberia. This hypothesis is consistent with demographic analyses, suggesting rapid clade A population increase while clade B is represented by stationary, fragmented populations. We recommend the eight, morphologically weakly diagnosable, subspecies of M. leprosa be reduced to two, reflecting major mtDNA clades: Mauremys l. leprosa (Iberian Peninsula and northern Morocco) and M. l. saharica (southern Morocco, eastern Algeria and Tunisia). Peripheral populations could play an important role in evolution of M. leprosa because we found endemic haplotypes in populations along the northern and southern range borders. Previous investigations in another western Palearctic freshwater turtle (Emys orbicularis) discovered similar differentiation of peripheral populations, and phylogeographies of Emys orbicularis and Mauremys rivulata underline the barrier status of mountain chains, in contrast to sea straits, suggesting common patterns for western Palearctic freshwater turtles.     

Interspecific interactions in the marine rotifer microcosm

Copepods and protozoans often co-exist in marinerotifer mass cultures. Interspecific interactionbetween the rotifer Brachionus rotundiformisTschugunoff and eight other zooplankton species,namely Brachionus plicatilis O. F. Müller (rotifer),Diaphanosoma celebensis Stingelin (cladoceran),Tigriopus japonicus Mori, Acartia sp. (copepod),Euplotes sp., Vorticella sp., an unidentifiedprotozoan species (P1 strain) (protozoan) and Artemiasp. (anostracan) at two developmental stages (nauplii –0.95 mm, 0 days old; adults – 3.3 mm, 19 days old) wereinvestigated in the laboratory.There was no contaminating species that contributedto an increase in rotifer population growth during theexperiments. Four types of interspecific interactionswere seen between B. rotundiformis and otherco-existing zooplankton species. These include effectson population growth: (1) both species declined, (2) onespecies is promoted while the other is not influenced,(3) one species is declined while the other is notinfluenced and (4) one species is promoted while theother declined. The first type was exhibited by B. rotundiformis vs B. plicatilis, B. rotundiformis vsD. celebensis and B. rotundiformis vs Artemia sp. The second type was exhibited by B. rotundiformis vsVorticella sp. and the third type by B. rotundiformisvs Euplotes sp. and B. rotundiformis vs T. japonicus. The fourth type was exhibited by B. rotundiformis vs Acartia sp. and B. rotundiformis vs P1 strain.     

Vicariant versus dispersal processes in the settlement of Pseudamnicola (Caenogastropoda,Hydrobiidae) in the Mediterranean Balearic Islands

The genus Pseudamnicola comprises a group of tiny springsnails inhabiting several continental and insular regions of the Mediterranean basin. Given the limited dispersal capabilities of these animals, it is difficult to explain the wide distribution range of the genus and, more specifically, its presence in isolated habitats, such as on islands. Thus, to investigate the process(es) that may explain these distribution patterns, we morphologically re‐described and genetically analysed the six Pseudamnicola (Pseudamnicola) species occurring in the Iberian Peninsula and the nearby Balearic Islands. Genetic relationships were explored by sequencing two mitochondrial (cytochrome c oxidase subunit I and 16S rRNA) and one nuclear (28S rRNA) gene in 19 populations. Our morphological study confirmed the presence of previously described species, whereas our phylogenetic results revealed three lineages within the subgenus: one clade grouping the species from Minorca Island with an Iberian Peninsula species, a second clade grouping the three species from Majorca Island, and a third clade that consists of a single species, which occurs in both the Iberian Peninsula and Ibiza Island. Calculated speciation times show that the cladogenetic events involving the insular species seem to have occurred after the current conformation of the Balearic Islands (c. 20 Mya). Therefore, the speciation process may have been related to subsequent transmarine colonizations, probably during the Messinian Salinity Crisis, and the Pleistocene glaciations when landmass corridors connected the islands with the continent. © 2014 The Linnean Society of London     

Postglacial dispersal of the European rabbit (Oryctolagus cuniculus) on the Iberian peninsula reconstructed from nested clade and mismatch analyses of mitochondrial DNA genetic variation

Nested clade analysis was applied to cytochrome b restriction site data previously obtained on 20 natural populations of the European rabbit across the Iberian Peninsula to test the hypothesis of postglacial dispersal from two main refugia, one in the northeast and the other in the southwest. Apart from historical fragmentation that resulted in geographic discontinuity of two distinct mitochondrial DNA (mtDNA) clades A and B, patterns of haplotype genetic variability have been shaped mostly by restricted gene flow via isolation by distance. The distribution of tip versus interior haplotypes suggests that dispersal occurred from both the southwestern and northeastern groups. Dispersal from the southwest had a north and northwest direction, whereas from the northeast it had mostly a western and southern orientation, with subsequent overlap in a southeastern-northwestern axis across the Iberian Peninsula. The analysis of the pairwise mismatch distribution of a 179-181-bp fragment of the mtDNA control region, for seven of those populations, further supports the idea that major patterns of dispersal were in the direction of central Iberia. Additionally, rabbit populations do not show signs of any significant loss of genetic diversity in the recent past, implying that they maintained large population sizes and structure throughout the ice ages. This is congruent with the fact that the Iberian Peninsula was itself a glacial refugium during Quaternary ice ages. Nonetheless, climatic oscillations of this period, although certainly milder than in northern Europe, were sufficient to affect the range distributions of Iberian organisms.     

Past tree range dynamics in the Iberian Peninsula inferred through phylogeography and palaeodistribution modelling: A review

The forests in the Iberian Peninsula have been strongly influenced by past climatic changes, but reconstructing their historical distributions and dynamics is very difficult due to the complex climatic characteristics and relief of the region. Research disciplines such as phylogeography and species distribution modelling can describe the past range dynamics of individual tree species in relatively great detail and help elucidate how these species have reacted to climatic changes. Here we review phylogeographical and modelling studies from species representative of the major Iberian forest types and attempt to extract general trends from the diversity of individual species histories in the Peninsula. To date most studies focus on geographical range dynamics during the Pleistocene, but an increasing body of evidence shows that some species have also retained the genetic imprints of much more ancient processes. Many widespread Iberian species show a deep and often remarkably clear-cut divide between populations from the Mediterranean and from the Atlantic regions of the Iberian Peninsula, suggesting that both areas have independently sustained viable populations over extended periods. In fact, phylogeographical studies commonly find that species had several glacial refugia across the Iberian Peninsula. On the other hand, distribution models help identifying further suitable areas that could have sustained so far undetected refugia. Such studies are of interest for species conservation, because refugium populations are high-priority targets due to their long-term persistence and unique evolutionary trajectory. Overall, we conclude that palaeoecology, phylogeography and species distribution modelling have a great potential to inform each other because of their complementary perspectives and results. A true integration of these approaches is therefore fundamental for further progress in our understanding of past Iberian environments and the organisms they harboured.     

褶皱臂尾轮虫同胞物种复合类群分类的研究进展

褶皱臂尾轮虫包含复杂的同胞物种,对其分类研究经过了一个长期发展的过程。综述了轮虫分类手段的发展进程,介绍和分析了轮虫特别是褶皱臂尾轮虫同胞物种复合类群分类的研究进展。褶皱臂尾轮虫的L-型和S-型属于B.plicatilis和B.rotundiformis两个物种。这个复合类群中还包括更多的种类,如B.plicatilis sensu stricto、B.ibericus和B.rotundiformis,其中B.plicatilis sensu stricto属于L型,B.ibericus属于SM-型,B.rotundiformis属于SS-型。此类研究丰富了轮虫系统分类学,提高了水域生态调查的准确性。     

Survival and long-term maintenance of tertiary trees in the Iberian Peninsula during the Pleistocene: first record of Aesculus L. (Hippocastanaceae) in Spain

The Italian and Balkan peninsulas have been places traditionally highlighted as Pleistocene glacial refuges. The Iberian Peninsula, however, has been a focus of controversy between geobotanists and palaeobotanists as a result of its exclusion from this category on different occasions. In the current paper, we synthesise geological, molecular, palaeobotanical and geobotanical data that show the importance of the Iberian Peninsula in the Western Mediterranean as a refugium area. The presence of Aesculus aff. hippocastanum L. at the Iberian site at Cal Guardiola (Tarrasa, Barcelona, NE Spain) in the Lower–Middle Pleistocene transition helps to consolidate the remarkable role of the Iberian Peninsula in the survival of tertiary species during the Pleistocene. The palaeodistribution of the genus in Europe highlights a model of area abandonment for a widely-distributed species in the Miocene and Pliocene, leading to a diminished and fragmentary presence in the Pleistocene and Holocene on the southern Mediterranean peninsulas. Aesculus fossils are not uncommon within the series of Tertiary taxa. Many appear in the Pliocene and suffer a radical impoverishment in the Lower–Middle Pleistocene transition. Nonetheless some of these tertiary taxa persisted throughout the Pleistocene and Holocene up to the present in the Iberian Peninsula. Locating these refuge areas on the Peninsula is not an easy task, although areas characterised by a sustained level of humidity must have played an predominant role.