Molecular species delimitation methods provide new insight into taxonomy of the endemic gammarid species flock from the ancient Lake Ohrid

Author(s):  
Michał Grabowski ◽  
Anna Wysocka ◽  
Tomasz Mamos
2010 ◽  
Vol 7 (11) ◽  
pp. 3387-3402 ◽  
Author(s):  
S. Trajanovski ◽  
C. Albrecht ◽  
K. Schreiber ◽  
R. Schultheiß ◽  
T. Stadler ◽  
...  

Abstract. Ancient Lake Ohrid on the Balkan Peninsula is considered to be the oldest ancient lake in Europe with a suggested Plio-/Pleistocene age. Its exact geological age, however, remains unknown. Therefore, molecular clock data of Lake Ohrid biota may serve as an independent constraint of available geological data, and may thus help to refine age estimates. Such evolutionary data may also help unravel potential biotic and abiotic factors that promote speciation events. Here, mitochondrial sequencing data of one of the largest groups of endemic taxa in the Ohrid watershed, the leech genus Dina, is used to test whether it represents an ancient lake species flock, to study the role of potential horizontal and vertical barriers in the watershed for evolutionary events, to estimate the onset of diversification in this group based on molecular clock analyses, and to compare this data with data from other endemic species for providing an approximate time frame for the origin of Lake Ohrid. Based on the criteria speciosity, monophyly and endemicity, it can be concluded that Dina spp. from the Ohrid watershed, indeed, represents an ancient lake species flock. Lineage sorting of its species, however, does not seem to be complete and/or hybridization may occur. Analyses of population structures of Dina spp. in the Ohrid watershed indicate a horizontal zonation of haplotypes from spring and lake populations, corroborating the role of lake-side springs, particularly the southern feeder springs, for evolutionary processes in endemic Ohrid taxa. Vertical differentiation of lake taxa, however, appears to be limited, though differences between populations from the littoral and the profundal are apparent. Molecular clock analyses indicate that the most recent common ancestor of extant species of this flock is approximately 1.99 ± 0.83 million years (Ma) old, whereas the split of the Ohrid Dina flock from a potential sister taxon outside the lake is estimated at 8.30 ± 3.60 Ma. Comparisons with other groups of endemic Ohrid species indicated that in all cases, diversification within the watershed started ≤2 Ma ago. Thus, this estimate may provide information on a minimum age for the origin of Lake Ohrid. Maximum ages are less consistent and generally less reliable. But cautiously, a maximum age of 3 Ma is suggested. Interestingly, this time frame of approximately 2–3 Ma ago for the origin of Lake Ohrid, generated based on genetic data, well fits the time frame most often used in the literature by geologists.


2021 ◽  
Vol 4 ◽  
Author(s):  
Anna Wysocka ◽  
Michal Grabowski ◽  
Lidia Sworobowicz ◽  
Sasho Trajanovski ◽  
Tomasz Mamos

Lake Ohrid, located on the Balkan Peninsula at the Albanian-Macedonian border, is the oldest European lake (1.3-1.9 My old) and one of the world’s smallest ancient lakes. Taking into account the size of the lake and its biodiversity, it harbors the highest level of endemism, especially within amphipod crustaceans (ca. 90%) with the endemic Gammarus species flock. Our previous studies upon this flock have shown a substantial decoupling between molecular and morphological diversity, existence of cryptic species and puzzling speciation history. In order to explore sources of observed diversity, in the current study we are investigating ecological preferences of the species within the flock, based on their distribution in depth gradient, in relation to molecular diversity based on DNA barcoding. In the study over 200 barcodes were generated and combined with 173 previously published. The specimens were collected from all depth ranges of Lake Ohrid as well as from springs located on or near the banks of the lake. Within the species flock, 13 BIN’s were identified, 12 previously known and one newly recognized, representing separate lineage and putatively a new species. Two of the flock species were found only in the springs: G. sketi and G. cryptosalemaai. G. sketi, previously found only in springs on the southern banks of Lake Ohrid, has now also been discovered in springs in its north-eastern part. Both species show low haplotypic diversity. All remaining species were recorded from the depth between 20 and 60 meters, that is characterized by the highest ecological diversity with different types of substrates: stones, macrophytes, abundant Dreissena shells as well as sand and silt. Among them G. sywulai, G. macedonicus, G. cryptoparechiniformis, G. lychnidensis, G. ochridensis, G. parechinifromis were found exclusively within this depth range. The three latter species represent single BIN and share haplotypes, at the same time this BIN has the highest number of haplotypes in comparison to others. The remaining species found on this depth represent separate BINs with different levels of haplotype diversity. Only G. lychnidensis, G. stankokaramani and G. solidus were found below the depth of 60 meters, in a quite homogenous environment dominated by silt. In the deepest parts of the lake, between 260 and 290 meters, only G. solidus was found. This species is represented only by three haplotypes while G. stankokaramani is characterized by multiple haplotypes partially shared with G. lychnidensis. The shared haplotype represents the only G. lychnidensis occurrences on the depths below 60 meters. Summarizing, the highest abundance of BINs, species and haplotypes was recovered from the most ecologically diversified depth range of the lake (20 to 60 meters). This suggests that ecological heterogeneity could be the main driver of Gammarus species flock diversification in the ancient Lake Ohrid. Due to the complex pattern of morphological diversity, DNA barcoding proved to be the best if not the only method in identification of the species flock diversity.


2021 ◽  
Author(s):  
◽  
Sergio Diaz Martinez

<p>Understanding speciation is one of the great challenges in evolutionary biology as many of the processes involved in speciation, as well as the forces leading to morphological and genetic differentiation, are not fully understood. Three main modes of speciation have been described: allopatric, parapatric and sympatric. Sympatric speciation is the most enigmatic mode because in the absence of physical barriers, disruptive selection, assortative mating and hybridization play central roles in reproductive isolation. Although it is accepted that sympatric speciation is possible, only a few examples of this process exist to date. Another common method of speciation in plants and algae is via polyploidization. Recently, a promising system to study speciation in sympatry was discovered: the endemic Cladophorales species flock in ancient Lake Baikal, Russia. The flock consists of sixteen taxa grouped in four genera: Chaetocladiella, Chaetomorpha, Cladophora and Gemmiphora. In spite of their morphological diversity, recent molecular analyses have shown that this is a monophyletic group with low genetic variation and nested within the morphologically simple genus Rhizoclonium. Due to their high number of species, endemism and sympatric distribution, many interesting questions have arisen such as what processes are involved in speciation, and whether this group might be a novel example of sympatric speciation. In this study, we analysed the population genetics of the endemic Baikalian Cladophorales to infer the processes shaping the evolution of the group. First, a set of microsatellites was designed using high-throughput sequencing data. Second, species delimitation methods based on genetic clustering were performed. Third, the population genetics of three widely distributed species was analysed looking for evidence of panmixia, a common criteria to support sympatric speciation. A total of 11 microsatellites that mostly cross-amplify between most species were obtained. The genotyping revealed that most loci had more than two alleles per individual indicating polyploidy. As such, the analyses required a different approach which consisted in coding the genotypes as ‘allelic phenotypes’, allowing the use of individuals of different ploidy levels in the same data set. The species delimitation of 15 operative morphotaxa and 727 individuals supported reproductive isolation of five morphotaxa and two hypotheses of conspecificity. However, some morphotaxa showed unclear assignments revealing the need of further research to clarify their reproductive limits. Finally, the population genetics of Chaetomorpha moniliformis, Cladophora compacta and Cl. kursanovii revealed patterns of genetic variation and structure that suggest different reproductive strategies and dispersal abilities. This demonstrates that contrasting biological characteristics may arise in closely related lineages: Chaetomorpha moniliformis with dominant asexual reproduction and long dispersal abilities; Cladophora compacta with high genetic diversity, no population structure and likely to reproduce sexually; Cl. kursanovii with a structure congruent with geographic distribution and more restricted dispersal. The results suggest that polyploidy, rather than speciation with gene flow, is the force driving the reproductive isolation and evolution of this flock. Although many questions remain to be studied, this research provides the first insights into the diversification of this Cladophorales species flock and contributes to the understanding of speciation in freshwater algae.</p>


2010 ◽  
Vol 7 (4) ◽  
pp. 5011-5045 ◽  
Author(s):  
S. Trajanovski ◽  
C. Albrecht ◽  
K. Schreiber ◽  
R. Schultheiß ◽  
T. Stadler ◽  
...  

Abstract. Ancient Lake Ohrid on the Balkan Peninsula is considered to be the oldest ancient lake in Europe with a suggested Plio-Pleistocene age. Its exact geological age, however, remains unknown. Therefore, molecular clock data of Lake Ohrid biota may serve as an independent constraint of available geological data, and may thus also help to refine age estimates. Such evolutionary data may also help unravel potential biotic and abiotic factors that promote speciation events. Here, mitochondrial sequencing data of one of the largest groups of endemic taxa in Lake Ohrid, the leech genus Dina, is used to test whether it represents an ancient lake species flock, to study the role of horizontal and vertical barriers in Lake Ohrid for evolutionary events, to estimate the onset of intralacustrine diversification in this group based on molecular clock analyses, and to compare this data with data from other endemic species for providing an approximate time frame for the origin of Lake Ohrid. Based on the criteria speciosity, monophyly and endemicity, it can be concluded that Lake Ohrid Dina, indeed, represents an ancient lake species flock. Lineage sorting of its species, however, does not seem to be complete. Analyses of population structures of Dina spp. in the Ohrid watershed indicate a horizontal zonation of haplotypes from spring and lake populations, corroborating the role of lake-side springs, particularly the southern feeder springs, for evolutionary processes in endemic Ohrid taxa. Vertical differentiation of lake taxa, however, appears to be limited, though differences between populations from the littoral and the profundal are apparent. Molecular clock analyses indicate that the most recent common ancestor of extant species of this flock is approximately 1.99±0.83 Ma old, whereas the split of the Lake Ohrid Dina flock from a potential sister taxon outside the lake is estimated at 8.30±3.60 Ma. Comparisons with other groups of endemic Ohrid species indicated that in all cases, intralacustrine diversification started ≤2 Ma ago. Thus, this estimate may provide information on a minimum age for the origin of Lake Ohrid. Maximum ages are less consistent and generally less reliable. But cautiously, a maximum age of 3 Ma is suggested. Interestingly, this time frame of approximately 2–3 Ma for the origin of Lake Ohrid, generated based solely on evolutionary data, well fits the time frame most often used in the literature by geologists. Future studies must show whether this concurrence holds true.


2021 ◽  
Author(s):  
◽  
Sergio Diaz Martinez

<p>Understanding speciation is one of the great challenges in evolutionary biology as many of the processes involved in speciation, as well as the forces leading to morphological and genetic differentiation, are not fully understood. Three main modes of speciation have been described: allopatric, parapatric and sympatric. Sympatric speciation is the most enigmatic mode because in the absence of physical barriers, disruptive selection, assortative mating and hybridization play central roles in reproductive isolation. Although it is accepted that sympatric speciation is possible, only a few examples of this process exist to date. Another common method of speciation in plants and algae is via polyploidization. Recently, a promising system to study speciation in sympatry was discovered: the endemic Cladophorales species flock in ancient Lake Baikal, Russia. The flock consists of sixteen taxa grouped in four genera: Chaetocladiella, Chaetomorpha, Cladophora and Gemmiphora. In spite of their morphological diversity, recent molecular analyses have shown that this is a monophyletic group with low genetic variation and nested within the morphologically simple genus Rhizoclonium. Due to their high number of species, endemism and sympatric distribution, many interesting questions have arisen such as what processes are involved in speciation, and whether this group might be a novel example of sympatric speciation. In this study, we analysed the population genetics of the endemic Baikalian Cladophorales to infer the processes shaping the evolution of the group. First, a set of microsatellites was designed using high-throughput sequencing data. Second, species delimitation methods based on genetic clustering were performed. Third, the population genetics of three widely distributed species was analysed looking for evidence of panmixia, a common criteria to support sympatric speciation. A total of 11 microsatellites that mostly cross-amplify between most species were obtained. The genotyping revealed that most loci had more than two alleles per individual indicating polyploidy. As such, the analyses required a different approach which consisted in coding the genotypes as ‘allelic phenotypes’, allowing the use of individuals of different ploidy levels in the same data set. The species delimitation of 15 operative morphotaxa and 727 individuals supported reproductive isolation of five morphotaxa and two hypotheses of conspecificity. However, some morphotaxa showed unclear assignments revealing the need of further research to clarify their reproductive limits. Finally, the population genetics of Chaetomorpha moniliformis, Cladophora compacta and Cl. kursanovii revealed patterns of genetic variation and structure that suggest different reproductive strategies and dispersal abilities. This demonstrates that contrasting biological characteristics may arise in closely related lineages: Chaetomorpha moniliformis with dominant asexual reproduction and long dispersal abilities; Cladophora compacta with high genetic diversity, no population structure and likely to reproduce sexually; Cl. kursanovii with a structure congruent with geographic distribution and more restricted dispersal. The results suggest that polyploidy, rather than speciation with gene flow, is the force driving the reproductive isolation and evolution of this flock. Although many questions remain to be studied, this research provides the first insights into the diversification of this Cladophorales species flock and contributes to the understanding of speciation in freshwater algae.</p>


2006 ◽  
Vol 6 (4) ◽  
pp. 294-307 ◽  
Author(s):  
C ALBRECHT ◽  
S TRAJANOVSKI ◽  
K KUHN ◽  
B STREIT ◽  
T WILKE

Diversity ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 428
Author(s):  
Martin Stervander ◽  
Bengt Hansson ◽  
Urban Olsson ◽  
Mark F. Hulme ◽  
Ulf Ottosson ◽  
...  

Larks constitute an avian family of exceptional cryptic diversity and striking examples of convergent evolution. Therefore, traditional morphology-based taxonomy has recurrently failed to reflect evolutionary relationships. While taxonomy ideally should integrate morphology, vocalizations, behaviour, ecology, and genetics, this can be challenging for groups that span several continents including areas that are difficult to access. Here, we combine morphometrics and mitochondrial DNA to evaluate the taxonomy of Calandrella larks, with particular focus on the African C. cinerea and the Asian C. acutirostris complexes. We describe a new range-restricted West African taxon, Calandrella cinerea rufipecta ssp. nov. (type locality: Jos, Plateau State, Nigeria), with an isolated relic population 3000 km from its closest relative in the Rift Valley. We performed molecular species delimitation, employing coalescence-based multi-rate Poisson Tree Processes (mPTP) on cytochrome b sequences across 52 currently recognized lark species, including multiple taxa currently treated as subspecies. Three species-level splits were inferred within the genus Calandrella and another 13 across other genera, primarily among fragmented sub-Saharan taxa and taxa distributed from Northwest Africa to Arabia or East Africa. Previously unknown divergences date back as far as to the Miocene, indicating the presence of currently unrecognized species. However, we stress that taxonomic decisions should not be based on single datasets, such as mitochondrial DNA, although analyses of mitochondrial DNA can be a good indicator of taxa in need of further integrative taxonomic assessment.


2021 ◽  
Author(s):  
Kenzi Takamura ◽  
Ryuhei Ueno ◽  
Natsuko Ito Kondo ◽  
Kako Ohbayashi

2020 ◽  
Vol 150 ◽  
pp. 106880
Author(s):  
Tonatiuh Ramírez-Reyes ◽  
Christopher Blair ◽  
Oscar Flores-Villela ◽  
Daniel Piñero ◽  
Amy Lathrop ◽  
...  

Zootaxa ◽  
2018 ◽  
Vol 4526 (4) ◽  
pp. 434
Author(s):  
ARTEM Y. SINEV ◽  
CHARO LÓPEZ-BLANCO

A new species of Cladocera, Alona begoniae sp. nov. (Anomopoda: Chydoridae) was found in ancient Lake Ohrid. Its habitus and outer morphology is similar to one of the most common Palearctic species, Coronatella rectangula (Sars, 1862), and this can be the main reason why it has remained undiscovered. A. begoniae sp. nov. belongs to the elegans-group of Alona s. lato, a relict genus-level group not formally recognised yet as a separate taxonomical unit. Its habitat seem to be sandy and stony substrates (at 2–12 m depth) bare of vegetation. The position of this new species within the Alona-like anomopods is evaluated and similarities with other cladocerans in ancient lakes are discussed. 


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