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1.
The sand goby Pomatoschistus minutus is a major component of marine shelf and estuarine food webs and an important study organism in behavioural research. Yet, despite the sand goby’s significance, its past and present patterns of migration and gene flow are poorly understood. Here we use the mtDNA control region and parts of the flanking tRNA genes of 63 fish from six localities in the Adriatic (Eastern Mediterranean), Western Mediterranean, Atlantic, and North Sea to investigate the phylogeography of this gobiid. Phylogenetic analyses and population genetics statistics reveal the existence of an Evolutionarily Significant Unit, sensu Moritz (1994), in the Adriatic and another in the Western Mediterranean, Atlantic, and North Sea. A possible biogeographical scenario for the separation of the ancestral population is that sand gobies in the Adriatic and Western Mediterranean split between 10,000 and 5000 years ago when due to the rise in sea temperature they migrated northwards and were bisected by the Italian peninsula. A testable prediction of this scenario is that sand gobies from the Western Mediterranean, Adriatic, and Aegean form three reciprocally monophyletic groups which are the descendants of a three-way diversification event.  相似文献   

2.
Habitat fragmentation is a major force that will influence the evolution of a species and its distribution range. Pomatoschistus minutus, the sand goby, has a North Atlantic–Mediterranean distribution and shows various level of habitat fragmentation along its geographic repartition. The use of mitochondrial sequences of the cytochrome b (cyt b) gene and two co‐dominant sets of nuclear markers (introns and microsatellites) allowed us to describe the relationships between P. minutus populations belonging to several different geographical regions of Europe and to assess the structure of populations inhabiting the Golfe du Lion, along the French Mediterranean coast. The present study confirms that the taxon located in the Adriatic Sea (Venice) should be considered as a distinct species, separated approximately 1.75 Mya. The comparison of P. minutus between the Atlantic and western Mediterranean coasts using polymorphic co‐dominant markers revealed that they belong to two demographically independent units, and thus could be considered as well as distinct species, more recently separated (0.3 Mya). The Pleistocene glaciations seem therefore to have played an important role in the diversification of this complex. Finally, at a regional scale in the Golfe du Lion, P. minutus appears to form a single huge homogeneous population. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 175–198.  相似文献   

3.
Sequence analysis of the mtDNA control region of four samples (n=195) of Atlantic bonito (Sarda sarda) collected along the northern Mediterranean reveals two clades about 8.1% divergent distributed in an east-west cline that fits an isolation by distance (IBD) model. The vicariant origin of this genetic discontinuity is proposed, supported in addition to the cline, by evidence of distinct historical demographic factors affecting each clade. Variation in Clade I suggests a large stable population, whereas Clade II displays a star-like phylogeny indicative of a population bottleneck followed by sudden expansion. The historical demography and biogeographic scenario is as follows: (1) Allopatric isolation during the Pleistocene give rise to Clade I (Atlantic) and Clade II (Mediterranean); (2) Population collapse followed by sudden expansion gives rise to the characteristic star-like phylogeny of Clade II; (3) Secondary contact as Clade I enters from the Atlantic, and (4) An east-west cline is maintained by IBD.  相似文献   

4.
The Patagonian steppe is an immense, cold, arid region, yet phylogeographically understudied. Nassauvia subgen. Strongyloma is a characteristic element of the steppe, exhibiting a continuum of morphological variation. This taxon provides a relevant phylogeographical model not only to understand how past environmental changes shaped the genetic structure of its populations, but also to explore phylogeographical scenarios at the large geographical scale of the Patagonian steppe. Here, we (1) assess demographic processes and historical events that shaped current geographic patterns of haplotypic diversity; (2) analyze hypotheses of isolation in refugia, fragmentation of populations, and/or colonization of available areas during Pleistocene glaciations; and (3) model extant and palaeoclimatic distributions to support inferred phylogeographical patterns. Chloroplast intergenic spacers, rpl32–trnL and trnQ–5′rps16, were sequenced for 372 individuals from 63 populations. Nested clade analysis, analyses of molecular variance, and neutrality tests were performed to assess genetic structure and range expansion. The present potential distribution was modelled and projected onto a last glacial maximum (LGM) model. Of 41 haplotypes observed, ten were shared among populations associated with different morphological variants. Populations with highest haplotype diversity and private haplotypes were found in central‐western and south‐eastern Patagonia, consistent with long‐term persistence in refugia during Pleistocene. Palaeomodelling suggested a shift toward the palaeoseashore during LGM; new available areas over the exposed Atlantic submarine platform were colonized during glaciations with postglacial retraction of populations. A scenario of fragmentation and posterior range expansion may explain the observed patterns in the center of the steppe, which is supported by palaeomodelling. Northern Patagonian populations were isolated from southern populations by the Chubut and the Deseado river basins during glaciations. Pleistocene glaciations indirectly impacted the distribution, demography, and diversification of subgen. Strongyloma through decreased winter temperatures and water availability in different areas of its range.  相似文献   

5.
The sand goby Pomatoschistus minutus is a major component of marine shelf and estuarine food webs and an important study organism in behavioural research. Yet, despite the sand goby's significance, its past and present patterns of migration and gene flow are poorly understood. Here we use the mtDNA control region and parts of the flanking tRNA genes of 63 fish from six localities in the Adriatic (Eastern Mediterranean), Western Mediterranean, Atlantic, and North Sea to investigate the phylogeography of this gobiid. Phylogenetic analyses and population genetics statistics reveal the existence of an Evolutionarily Significant Unit, sensu Moritz (1994), in the Adriatic and another in the Western Mediterranean, Atlantic, and North Sea. A possible biogeographical scenario for the separation of the ancestral population is that sand gobies in the Adriatic and Western Mediterranean split between 10,000 and 5000 years ago when due to the rise in sea temperature they migrated northwards and were bisected by the Italian peninsula. A testable prediction of this scenario is that sand gobies from the Western Mediterranean, Adriatic, and Aegean form three reciprocally monophyletic groups which are the descendants of a three-way diversification event.  相似文献   

6.
Mediterranean monk seals (MMS) are among the most endangered marine mammals on Earth. We screened mitochondrial variability (control region [CR1] and mitogenomes) of the species through a 180‐yr timeframe and extended by 20% (n = 205) the number of samples from a previous investigation, including historical specimens from 1833 to 1975. Although we detected two new, rare CR1 haplotypes, genetic diversity remained extremely low. Fully resolved haplotype median network and rarefaction analysis both suggested low probability for further unscreened haplotypes. There was no clear phylogeographic structure across the 12 marine subdivisions covered by the species’ range. Haplotypes previously considered diagnostic of the extant North Atlantic and eastern Mediterranean populations had their distributions extended into the western Mediterranean and the North Atlantic, respectively, by both historical and recent samples. Our study suggests that MMS have been genetically depauperate since at least the mid‐19th century, and that the massive 1997 die‐off in Western Sahara (North Atlantic) could have caused local haplotype extinctions. Our results support the hypothesis of past metapopulation dynamics across the species range, where the current segregation into geographically distant and genetically depauperate breeding populations (i.e., North Atlantic and eastern Mediterranean Sea) derives from the combined effects of historical extinctions, genetic drift on small breeding groups, and persistently low levels of genetic diversity.  相似文献   

7.
Aim Natural processes of colonization and human‐mediated introductions have shaped current patterns of biodiversity in the Mediterranean Basin. We use a comparative phylogeographic approach to investigate the genetic structure of Herpestes ichneumon and Genetta genetta (Carnivora) across the Strait of Gibraltar, and test for their supposedly contemporaneous introduction into Iberia. Location Mediterranean Basin and Africa. Methods We sequenced two mitochondrial fragments (cytochrome b and control region) of 91 (H. ichneumon) and 185 (G. genetta) individuals, including the sole archaeological record of G. genetta in Iberia, dating from the Muslim occupation. We used phylogenetic and tokogenetic methods, summary statistics, neutrality tests, geographic–genetic pairwise comparisons and coalescent estimates to explore the history of the two species in the Mediterranean Basin. Results In North Africa, an autochthonous (Clade I) and a western African mtDNA clade, coalescing in the Middle to Late Pleistocene, co‐occurred in both species. Only Clade I was present in Europe. In H. ichneumon, the European pool showed deep coalescence (median = 335 kyr) and high genetic differentiation and diversity compared with its North African counterpart, suggesting long‐term stability of female effective population size. In sharp contrast, G. genetta in Europe exhibited lower genetic diversity, weak differentiation with North Africa and recent demographic expansion; however, Andalusia and Catalonia (Spain) showed distinctly higher genetic diversity, and the archaeological specimen had the predominant European haplotype. Main conclusions The co‐occurrence of autochthonous and sub‐Saharan lineages in North Africa (1) supports a new, emerging biogeographic scenario in North Africa, and (2) suggests a connection through the Sahara, possibly from the Middle Pleistocene onwards. Our results refute the idea that H. ichneumon was introduced into Europe contemporaneously with G. genetta. Instead, they support a scenario of sweepstake dispersal during Late Pleistocene sea‐level fluctuations, followed by long‐term in situ evolution throughout the last glaciation cycles. Genetta genetta appears to have undergone a recent spread from at least two independent introduction ‘hotspots’ in Catalonia and Andalusia, possibly following antique trade routes and/or Muslim invasions. Despite their contrasting histories, the European gene pools of both species represent unusual cases leading to the preservation of autochthonous, North African lineages.  相似文献   

8.
The demographic history of Rhinolophus hipposideros (lesser horseshoe bat) was reconstructed across its European, North African and Middle‐Eastern distribution prior to, during and following the most recent glaciations by generating and analysing a multimarker data set. This data set consisted of an X‐linked nuclear intron (Bgn; 543 bp), mitochondrial DNA (cytb‐tRNA‐control region; 1630 bp) and eight variable microsatellite loci for up to 373 individuals from 86 localities. Using this data set of diverse markers, it was possible to determine the species’ demography at three temporal stages. Nuclear intron data revealed early colonization into Europe from the east, which pre‐dates the Quaternary glaciations. The mtDNA data supported multiple glacial refugia across the Mediterranean, the largest of which were found in the Ibero‐Maghreb region and an eastern location (Anatolia/Middle East)–that were used by R. hipposideros during the most recent glacial cycles. Finally, microsatellites provided the most recent information on these species’ movements since the Last Glacial Maximum and suggested that lineages that had diverged into glacial refugia, such as in the Ibero‐Maghreb region, have remained isolated. These findings should be used to inform future conservation management strategies for R. hipposideros and show the power of using a multimarker data set for phylogeographic studies.  相似文献   

9.
Different scales and frequencies of glaciations developed in Europe and Asia during the Pleistocene. Because species’ responses to climate change are influenced by interactive factors including ecology and local topography, the pattern and tempo of species diversification may vary significantly across regions. The great tit Parus major is a widespread Eurasian passerine with a range that encircles the central Asian desert and high‐altitude areas of the Tibetan Plateau. A number of genetic studies have assessed the effect of paleo‐climate changes on the distribution of the European population. However, none have comprehensively addressed how paleo‐climate change affected the distribution of the great tit in China, an apparent hotspot of P. major subspecific diversity. Here, we describe likely paleo‐climatic effects on P. major populations in China based on a combination of phylogeography and ecological niche models (ENMs). We sequenced three mitochondrial DNA markers from 28 populations (213 individuals), and downloaded 112 sequences from outside its Chinese range. As the first step in clarifying the intra‐specific relationships among haplotypes, we attempted to clarify the divergence and demography of populations in China. Phylogeographic analysis revealed that P. major is comprised of five highly divergent clades with geographic breaks corresponding to steep mountains and dry deserts. A previously undescribed monophyletic clade with high genetic diversity, stable niches and a long and independent evolutionary history was detected in the mountainous areas of southwest China. The estimated times at which these clades diverged was traced back to the Early‐Middle Pleistocene (2.19–0.61 mya). Contrary to the post‐LGM (the Last Glacial Maximum) expansion of European populations, demographic history indicates that Asian populations expanded before the LGM after which they remained relatively stable or grew slowly through the LGM. ENMs support this conclusion and predict a similar distribution in the present and the LGM. Our genetic and ecological results demonstrate that Pleistocene climate changes shaped the divergence and demography of P. major in China.  相似文献   

10.
Vertical divergence in marine organisms is being increasingly documented, yet much remains to be carried out to understand the role of depth in the context of phylogeographic reconstruction and the identification of management units. An ideal study system to address this issue is the beaked redfish, Sebastes mentella – one of four species of ‘redfish’ occurring in the North Atlantic – which is known for a widely distributed ‘shallow‐pelagic’ oceanic type inhabiting waters between 250 and 550 m, and a more localized ‘deep‐pelagic’ population dwelling between 550 and 800 m, in the oceanic habitat of the Irminger Sea. Here, we investigate the extent of population structure in relation to both depth and geographic spread of oceanic beaked redfish throughout most of its distribution range. By sequencing the mitochondrial control region of 261 redfish collected over a decadal interval, and combining 160 rhodopsin coding nuclear sequences and previously genotyped microsatellite data, we map the existence of two strongly divergent evolutionary lineages with significantly different distribution patterns and historical demography, and whose genetic variance is mostly explained by depth. Combined genetic data, analysed via independent approaches, are consistent with a Late Pleistocene lineage split, where segregation by depth probably resulted from the interplay of climatic and oceanographic processes with life history and behavioural traits. The ongoing process of diversification in North Atlantic S. mentella may serve as an ‘hourglass’ to understand speciation and adaptive radiation in Sebastes and in other marine taxa distributed across a depth gradient.  相似文献   

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