On one hand, studies on
Salmo
biological variations during the last centuries have led to the morphological description of several
Salmo
species (> 50). On the other hand,
Salmo trutta
is seen as a ...polymorphic species, i.e. including populations with different morphotypes and ecotypes, subdivided into nine genetically divergent evolutionary lineages. For 30 years, phylogeographic and phylogenetic investigations tried to solve the
Salmo
systematic problem using the mitochondrial control region, sometimes combined with other mitochondrial (e.g. protein-coding region or rRNA genes) or nuclear (e.g. allozymes or microsatellites) markers. With the advent of high-throughput next-generation sequencing, complete mitogenomes were made available for
Salmo
phylogenetic studies. Even better, complete genome or chromosomes with annotations as well as genes of interest can now be loaded from public database. However, in the genomic era, some challenges still need to be addressed such as an appropriate taxon sampling or the identification of orthologous genes before having an accurate phylogeny. In the present review, I examine how traditional molecular markers contributed to our knowledge of trout systematics, and what we can expect from the genomics revolution.
The main objective of this work was to develop and validate a robust and reliable “from‐benchtop‐to‐desktop” metabarcoding workflow to investigate the diet of invertebrate‐eaters. We applied our ...workflow to faecal DNA samples of an invertebrate‐eating fish species. A fragment of the cytochrome c oxidase I (COI) gene was amplified by combining two minibarcoding primer sets to maximize the taxonomic coverage. Amplicons were sequenced by an Illumina MiSeq platform. We developed a filtering approach based on a series of nonarbitrary thresholds established from control samples and from molecular replicates to address the elimination of cross‐contamination, PCR/sequencing errors and mistagging artefacts. This resulted in a conservative and informative metabarcoding data set. We developed a taxonomic assignment procedure that combines different approaches and that allowed the identification of ~75% of invertebrate COI variants to the species level. Moreover, based on the diversity of the variants, we introduced a semiquantitative statistic in our diet study, the minimum number of individuals, which is based on the number of distinct variants in each sample. The metabarcoding approach described in this article may guide future diet studies that aim to produce robust data sets associated with a fine and accurate identification of prey items.
Through the study of the phylogeographic structure and demographic history of the common goby, Pomatoschistus microps, the influence of Quaternary climatic changes on the evolutionary history of ...coastal and marine fishes is investigated. Because of its sedentary life cycle in Mediterranean lagoons, it is also a good model to study more specifically if the formation of lagoons during the Holocene had an impact on population structure and demography. Mitochondrial sequences of Northeastern Atlantic and Western Mediterranean specimens were used for phylogenetic reconstructions as well as divergence time estimates, demographic history and population structure analyses. Pomatoschistus microps was a highly supported monophyletic clade including four lineages. It may have appeared 77,000 yr ago, and the divergence of its lineages likely occured shortly thereafter (between 61,000 and 54,000 yr). Most lineages had polytomic topologies, low nucleotide diversity and demographic analyses providing evidence of population expansion. Each lineage was characterized by a large number of private haplotypes. Most haplotypes found in Mediterranean localities were endemic, and one was dominant. Complex reticulated relationships connecting North European, Atlantic and Mediterranean haplotypes were observed. Moderate to high population structure was underlined. Contrary to previous published studies, no significant differentiation was observed between Atlantic and Mediterranean populations, indicating that the Gibraltar Strait is not a phylogeographic break for P. microps. Indeed, molecular dating combined with the tree topologies, phylogeographic and demographic analyses as well as high haplotype diversity underline a recent and rapid population divergence during the last glacial. However, population structure indicates that differentiation is an ongoing process. From an ancestral population trapped in the Atlantic, this goby colonized first northern Europe and later the Mediterranean Sea. Shared haplotypes could have dispersed in the western Mediterranean basin before the lagoon formation, while most private haplotypes, evidencing a recent isolation, probably diverged in lagoons after their closure.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Knowledge on faunal diversification in African rainforests remains scarce. We used phylogeography to assess (i) the role of Pleistocene climatic oscillations in the diversification of the African ...common pangolin (Manis tricuspis) and (ii) the utility of our multilocus approach for taxonomic delineation and trade tracing of this heavily poached species. We sequenced 101 individuals for two mitochondrial DNA (mtDNA), two nuclear DNA and one Y‐borne gene fragments (totalizing 2602 bp). We used a time‐calibrated, Bayesian inference phylogenetic framework and conducted character‐based, genetic and phylogenetic delineation of species hypotheses within African common pangolins. We identified six geographic lineages partitioned into western Africa, Ghana, the Dahomey Gap, western central Africa, Gabon and central Africa, all diverging during the Middle to Late Pleistocene. MtDNA (cytochrome b + control region) was the sole locus to provide diagnostic characters for each of the six lineages. Tree‐based Bayesian delimitation methods using single‐ and multilocus approaches gave high support for ‘species’ level recognition of the six African common pangolin lineages. Although the diversification of African common pangolins occurred during Pleistocene cyclical glaciations, causative correlation with traditional rainforest refugia and riverine barriers in Africa was not straightforward. We conclude on the existence of six cryptic lineages within African common pangolins, which might be of major relevance for future conservation strategies. The high discriminative power of the mtDNA markers used in this study should allow an efficient molecular tracing of the regional origin of African common pangolin seizures.
Island evolution may be expected to involve fast initial morphological divergence followed by stasis. We tested this model using the dental phenotype of modern and ancient common voles (Microtus ...arvalis), introduced onto the Orkney archipelago (Scotland) from continental Europe some 5000 years ago. First, we investigated phenotypic divergence of Orkney and continental European populations and assessed climatic influences. Second, phenotypic differentiation among Orkney populations was tested against geography, time, and neutral genetic patterns. Finally, we examined evolutionary change along a time series for the Orkney Mainland. Molar gigantism and anterior-lobe hypertrophy evolved rapidly in Orkney voles following introduction, without any transitional forms detected. Founder events and adaptation appear to explain this initial rapid evolution. Idiosyncrasy in dental features among different island populations of Orkney voles is also likely the result of local founder events following Neolithic translocation around the archipelago. However, against our initial expectations, a second marked phenotypic shift occurred between the 4th and 12th centuries AD, associated with increased pastoral farming and introduction of competitors (mice and rats) and terrestrial predators (foxes and cats). These results indicate that human agency can generate a more complex pattern of morphological evolution than might be expected in island rodents.
Both morphological and molecular data are presented and discussed for indigenous
Salmo
sp. from Corsica and Sardinia, here called Tyrrhenian trout. For comparison, morphological data obtained from ...museum specimens, including the Algerian
S. macrostigma
, are discussed in the light of recent and new molecular findings. In total, 29 measurements and 20 meristic characters were taken from each specimen. Out of the meristic characters, 12 were obtained by means of X-ray. One important morphometric character in the present study is the size of the head measured from premaxilla to posterior margin of preoperculum. This character was particularly stable in all Tyrrhenian trout, showing relatively large head compared to Atlantic trout and to
S
.
macrostigma
. On the contrary, other characters like body punctuations, black and white edges of fins, body depth or number of epurals in the caudal skeleton are quite polymorphic. In certain meristic characters, range of variation of Tyrrhenian trout even exceeds that of the extensive comparative material. Each trout has been genetically characterized. New haplotypes from Tyrrhenian trout were discovered, belonging to three mitochondrial lineages viz. Adriatic, marble and Mediterranean, however, Adriatic haplotypes are dominant. Comparing morphological and genetic data, observed morphology lacks any obvious correlation to mitochondrial lineages and it is concluded that Tyrrhenian trout show no particular affinity to
S
.
macrostigma
from Algeria.
La présente étude détaille et discute les données morphologiques et moléculaires des truites indigènes,
Salmo
sp. de Corse et de Sardaigne, ici appelée truites tyrrhéniennes. À titre de comparaison, les données morphologiques obtenues à partir de spécimens de musée, y compris
S. macrostigma
d'Algérie, sont discutées à la lumière des découvertes moléculaires récentes et nouvelles. Au total, 29 mesures et 20 caractères méristiques ont été considérés pour chaque spécimen. Parmi ces caractères méristiques, 12 ont été obtenus au moyen de rayons X. Un caractère morphométrique important dans la présente étude est la taille de la tête mesurée du prémaxillaire à la marge postérieure du préopercule. Ce caractère est particulièrement stable chez toutes les truites tyrrhéniennes, qui ont montré une tête relativement grande par rapport à celle de la truite de l'Atlantique et de
S. macrostigma
. Au contraire, d'autres caractères comme les ponctuations du corps, les franges noires et blanches des nageoires, la profondeur du corps ou le nombre d'hypuraux dans le squelette caudal sont assez polymorphes. Pour certains caractères méristiques, la gamme de variation de la truite tyrrhénienne dépasse celle de tous les taxons comparés. Chaque truite a été génétiquement caractérisée et de nouveaux haplotypes de truite tyrrhénienne ont été découverts, appartenant à trois lignées mitochondriales à savoir les lignées adriatique, marbrée et méditerranéenne, les haplotypes adriatiques étant dominants. En combinant les données morphologiques et génétiques, il est montré que la morphologie n'a aucune corrélation évidente avec les lignées mitochondriales. D'autre part, la truite tyrrhénienne n'a aucune affinité particulière avec
S. macrostigma
d'Algérie.
Elucidating the colonization processes associated with Quaternary climatic cycles is important in order to understand the distribution of biodiversity and the evolutionary potential of temperate ...plant and animal species. In Europe, general evolutionary scenarios have been defined from genetic evidence. Recently, these scenarios have been challenged with genetic as well as fossil data. The origins of the modern distributions of most temperate plant and animal species could predate the Last Glacial Maximum. The glacial survival of such populations may have occurred in either southern (Mediterranean regions) and/or northern (Carpathians) refugia. Here, a phylogeographic analysis of a widespread European small mammal (Microtus arvalis) is conducted with a multidisciplinary approach. Genetic, fossil and ecological traits are used to assess the evolutionary history of this vole. Regardless of whether the European distribution of the five previously identified evolutionary lineages is corroborated, this combined analysis brings to light several colonization processes of M. arvalis. The species' dispersal was relatively gradual with glacial survival in small favourable habitats in Western Europe (from Germany to Spain) while in the rest of Europe, because of periglacial conditions, dispersal was less regular with bottleneck events followed by postglacial expansions. Our study demonstrates that the evolutionary history of European temperate small mammals is indeed much more complex than previously suggested. Species can experience heterogeneous evolutionary histories over their geographic range. Multidisciplinary approaches should therefore be preferentially chosen in prospective studies, the better to understand the impact of climatic change on past and present biodiversity.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Evaluating biodiversity and understanding the processes involved in diversification are noticeable conservation issues in fishes subject to large, sometimes illegal, ornamental trade purposes. Here, ...the diversity and evolutionary history of the Neotropical dwarf cichlid genus Apistogramma from several South American countries are investigated. Mitochondrial and nuclear markers are used to infer phylogenetic relationships between 31 genetically identified species. The monophyly of Apistogramma is suggested, and Apistogramma species are distributed into four clades, corresponding to three morphological lineages. Divergence times estimated with the Yule process and an uncorrelated lognormal clock dated the Apistogramma origin to the beginning of the Eocene (≈ 50 Myr) suggesting that diversification might be related to marine incursions. Our molecular dating also suggests that the Quaternary glacial cycles coincide with the phases leading to Apistogramma speciation. These past events did not influence diversification rates in the speciose genus Apistogramma, since diversification appeared low and constant through time. Further characterization of processes involved in recent Apistogramma diversity will be necessary.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The objective of this study was to establish whether the Quaternary climatic fluctuations influenced the tempo and mode of diversification in European rodents. Our case study is the subgenus Microtus ...(Terricola) distributed from western Europe to the Caucasus. Mitochondrial cytochrome b gene sequences from several representatives of all the species were used to generate maximum‐likelihood and Bayesian phylogenetic trees, to estimate divergence times, to identify biogeographic ancestral areas and to study the rate of diversification. Results showed that phylogenetic tree topologies were similar to previous published studies but with a better resolution at some nodes. The origin of Microtus (Terricola) is dated back to approximately 4.05 Myr in the Early Pliocene, and molecular dating for most Terricola species corresponds to several glacial periods of the Pleistocene. Results of the biogeographic ancestral area reconstruction suggest that Microtus (Terricola) diversified from the Caucasus/Turkey/Iran area through western Europe. Several periods of diversity variation were highlighted as follows: two period of diversity increase, between 3 and 2 Myr, and after 1 Myr; two periods of diversity decrease, before 3 Myr, and between 2 and 1 Myr. The diversification rate of Microtus (Terricola) was 0.353 ± 0.004 event/Myr, a rate similar to that of the Muridae family. To conclude, although the Pleistocene glacial conditions had an impact on the speciation events, the Quaternary does not appear however as a period with an exceptional rate of diversification for European rodents.
Microtus (Terricola) is particularly suitable to understand whether and how the Quaternary climatic fluctuations could have promoted the diversification of rapid evolving small mammals such as rodents in temperate zones. Mitochondrial sequences were used to generate phylogenetic trees, to estimate divergence times, to identify biogeographic ancestral areas and to study diversification rates. Results showed that the Quaternary would not be a period with an exceptional diversification rate for European rodents, although Pleistocene glacial conditions had an impact on speciation events.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
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