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  • Fondi, Marco; Karkman, Antti; Tamminen, Manu V.; Bosi, Emanuele; Virta, Marko; Fani, Renato; Alm, Eric; McInerney, James O. (2016)
    The spatial distribution of microbes on our planet is famously formulated in the Baas Becking hypothesis as everything is everywhere but the environment selects." While this hypothesis does not strictly rule out patterns caused by geographical effects on ecology and historical founder effects, it does propose that the remarkable dispersal potential of microbes leads to distributions generally shaped by environmental factors rather than geographical distance. By constructing sequence similarity networks from uncultured environmental samples, we show that microbial gene pool distributions are not influenced nearly as much by geography as ecology, thus extending the Bass Becking hypothesis from whole organisms to microbial genes. We find that gene pools are shaped by their broad ecological niche (such as sea water, fresh water, host, and airborne). We find that freshwater habitats act as a gene exchange bridge between otherwise disconnected habitats. Finally, certain antibiotic resistance genes deviate from the general trend of habitat specificity by exhibiting a high degree of cross-habitat mobility. The strong cross-habitat mobility of antibiotic resistance genes is a cause for concern and provides a paradigmatic example of the rate by which genes colonize new habitats when new selective forces emerge.
  • Cornetti, Luca; Fields, Peter D.; Van Damme, Kay; Ebert, Dieter (2019)
    In the post-genomic era, much of phylogenetic analyses still relies on mitochondrial DNA, either alone or in combination with few nuclear genes. Although this approach often makes it possible to construct well-supported trees, it is limited because mtDNA describes the history of a single locus, and nuclear phylogenies based on a few loci may be biased, leading to inaccurate tree topologies and biased estimations of species divergence time. In this study, we perform a phylogenomic analysis of the Daphniidae family (Crustacea: Branchiopoda: Anomopoda) including some of the most frequently studied model organisms (Daphnia magna and D. pulex) whose phylogenetic relationships have been based primarily on an assessment of a few mtDNA genes. Using high-throughput sequencing, we were able to assemble 38 whole mitochondrial genomes and draft nuclear genomes for 18 species, including at least one species for each known genus of the family Daphniidae. Here we present phylogenies based on 636 nuclear single-copy genes shared among all sampled taxa and based on whole mtDNA genomes. The phylogenies we obtained were highly supported and showed some discrepancies between nuclear and mtDNA based trees at deeper nodes. We also identified a new candidate sister lineage of Daphnia magna. Our time-calibrated genomic trees, which we constructed using both fossil records and substitution rates, yielded very different estimates of branching event times compared to those based on mtDNA. By providing multi-locus, fossil-calibrated trees of the Daphniidae, our study contributes to an improved phylogenetic framework for ecological and evolutionary studies that use water fleas as a model system.
  • Partanen, Pasi; Hultman, Jenni; Paulin, Lars; Auvinen, Petri; Romantschuk, Martin (2010)
  • Immanen, Juha; Nieminen, Kaisa; Duchens Silva, Hector; Rodriguez Rojas, Fernanda; Meisel, Lee A.; Silva, Herman; Albert, Victor A.; Hvidsten, Torgeir R.; Helariutta, Yrjö (2013)
  • Sun, Zhihong; Harris, Hugh M. B.; McCann, Angela; Guo, Chenyi; Argimon, Silvia; Zhang, Wenyi; Yang, Xianwei; Jeffery, Ian B.; Cooney, Jakki C.; Kagawa, Todd F.; Liu, Wenjun; Song, Yuqin; Salvetti, Elisa; Wrobel, Agnieszka; Rasinkangas, Pia; Parkhill, Julian; Rea, Mary C.; O'Sullivan, Orla; Ritari, Jarmo; Douillard, Francois P.; Ross, R. Paul; Yang, Ruifu; Briner, Alexandra E.; Felis, Giovanna E.; de Vos, Willem M.; Barrangou, Rodolphe; Klaenhammer, Todd R.; Caufield, Page W.; Cui, Yujun; Zhang, Heping; O'Toole, Paul W. (2015)
    Lactobacilli are a diverse group of species that occupy diverse nutrient-rich niches associated with humans, animals, plants and food. They are used widely in biotechnology and food preservation, and are being explored as therapeutics. Exploiting lactobacilli has been complicated by metabolic diversity, unclear species identity and uncertain relationships between them and other commercially important lactic acid bacteria. The capacity for biotransformations catalysed by lactobacilli is an untapped biotechnology resource. Here we report the genome sequences of 213 Lactobacillus strains and associated genera, and their encoded genetic catalogue for modifying carbohydrates and proteins. In addition, we describe broad and diverse presence of novel CRISPR-Cas immune systems in lactobacilli that may be exploited for genome editing. We rationalize the phylogenomic distribution of host interaction factors and bacteriocins that affect their natural and industrial environments, and mechanisms to withstand stress during technological processes. We present a robust phylogenomic framework of existing species and for classifying new species.
  • Pavic, Ana; Ji, Yurui; Serafini, Agnese; Garza-Garcia , Acely; J. McPhillie, Martin; Holmes, Alexandra O. M.; Sório de Carvalho , Luiz Pedro; Wang, Yingying; Bartlam, Mark; Goldman, Adrian; Postis, Vincent L. G. (2021)
    Characterizing the mycobacterial transporters involved in the uptake and/or catabolism of host-derived nutrients required by mycobacteria may identify novel drug targets against tuberculosis. Here, we identify and characterize a member of the amino acid-polyamine-organocation superfamily, a potential gamma-aminobutyric acid (GABA) transport protein, GabP, from Mycobacterium smegmatis. The protein was expressed to a level allowing its purification to homogeneity, and size exclusion chromatography coupled with multiangle laser light scattering (SEC-MALLS) analysis of the purified protein showed that it was dimeric. We showed that GabP transported gamma-aminobutyric acid both in vitro and when overexpressed in E. coli. Additionally, transport was greatly reduced in the presence of beta-alanine, suggesting it could be either a substrate or inhibitor of GabP. Using GabP reconstituted into proteoliposomes, we demonstrated that gamma-aminobutyric acid uptake is driven by the sodium gradient and is stimulated by membrane potential. Molecular docking showed that gamma-aminobutyric acid binds MsGabP, another Mycobacterium smegmatis putative GabP, and the Mycobacterium tuberculosis homologue in the same manner. This study represents the first expression, purification, and characterization of an active gamma-aminobutyric acid transport protein from mycobacteria. IMPORTANCE The spread of multidrug-resistant tuberculosis increases its global health impact in humans. As there is transmission both to and from animals, the spread of the disease also increases its effects in a broad range of animal species. Identifying new mycobacterial transporters will enhance our understanding of mycobacterial physiology and, furthermore, provides new drug targets. Our target protein is the gene product of msmeg_6196, annotated as GABA permease, from Mycobacterium smegmatis strain MC2 155. Our current study demonstrates it is a sodium-dependent GABA transporter that may also transport beta-alanine. As GABA may well be an essential nutrient for mycobacterial metabolism inside the host, this could be an attractive target for the development of new drugs against tuberculosis.
  • Liu, Li-Na; Razaq, Abdul; Atri, Narender Singh; Bau, Tolgor; Belbahri, Lassaad; Bouket, Ali Chenari; Chen, Lai-Ping; Deng, Chu; Ilyas, Sobia; Khalid, Abdul Nasir; Kitaura, Marcos Junji; Kobayashi, Takahito; Li, Yu; Lorenz, Aline Pedroso; Ma, Yuan-Hao; Malysheva, Ekaterina; Malysheva, Vera; Nuytinck, Jorinde; Qiao, Min; Saini, Munruchi Kaur; Scur, Mayara Camila; Sharma, Samidha; Shu, Li-Li; Spirin, Viacheslav; Tanaka, Yoshikazu; Tojo, Motoaki; Uzuhashi, Shihomi; Valerio-Junior, Claudio; Verbeken, Annemieke; Verma, Balwant; Wu, Ri-Han; Xu, Jian-Ping; Yu, Ze-Fen; Zeng, Hui; Zhang, Bo; Banerjee, Arghya; Beddiar, Arifa; Bordallo, Juan-Julian; Dafri, Ahlem; Dima, Balint; Krisai-Greilhuber, Irmgard; Lorenzini, Marilinda; Mandal, Raghunath; Morte, Asuncion; Nath, Partha Sarathi; Papp, Viktor; Pavlik, Jozef; Rodriguez, Antonio; Sevcikova, Hana; Urban, Alexander; Voglmayr, Hermann; Zapparoli, Giacomo (2018)
    Eight new species presented are Calostoma areolatum collected in Wuyishan National Park (China), Crinipellis bidens from Hubei Province (China), Lactifluus sainii from Himalayan India, Inocybe elata from Yunnan (China), Inocybe himalayensis from Pakistan. Specimens previously identified as Massalongia carnosa represent a new species, namely M. patagonica restricted to southern South America. Saprolegnia maragheica is a new oomycete species of fresh water in Maraghe (Iran). Uncispora wuzhishanensis is a new aquatic hyphomycete species. A type specimen of Raddetes turkestanicus was studied and based on this the new combination Conocybe turkestanica, is proposed. Argyranthemum frutescens is a new host for Alternaria alternata and Syzygium cumini for Phyllosticta capitalensis in India. Crepidotus ehrendorferi is confirmed for Hungary and Pluteus leucoborealis for Central Europe, and for the phytogeographical region of Carpaticum. Pseudopithomyces palmicola is shown to occur on grapevine and it is validated by adding a unique identifier. Terfezia fanfani is reported first from Algeria.
  • EuroEPINOMICS-RES Consortium; Lal, Dennis; May, Patrick; Perez-Palma, Eduardo; Kurki, Mitja; Palotie, Aarno; Daly, Mark J.; Lehesjoki, Anna-Elina (2020)
    Background Classifying pathogenicity of missense variants represents a major challenge in clinical practice during the diagnoses of rare and genetic heterogeneous neurodevelopmental disorders (NDDs). While orthologous gene conservation is commonly employed in variant annotation, approximately 80% of known disease-associated genes belong to gene families. The use of gene family information for disease gene discovery and variant interpretation has not yet been investigated on a genome-wide scale. We empirically evaluate whether paralog-conserved or non-conserved sites in human gene families are important in NDDs. Methods Gene family information was collected from Ensembl. Paralog-conserved sites were defined based on paralog sequence alignments; 10,068 NDD patients and 2078 controls were statistically evaluated for de novo variant burden in gene families. Results We demonstrate that disease-associated missense variants are enriched at paralog-conserved sites across all disease groups and inheritance models tested. We developed a gene family de novo enrichment framework that identified 43 exome-wide enriched gene families including 98 de novo variant carrying genes in NDD patients of which 28 represent novel candidate genes for NDD which are brain expressed and under evolutionary constraint. Conclusion This study represents the first method to incorporate gene family information into a statistical framework to interpret variant data for NDDs and to discover new NDD-associated genes.
  • Tugume, Arthur K.; Amayo, Robert; Weinheimer, Isabel; Mukasa, Settumba B.; Rubaihayo, Patrick R.; Valkonen, Jari P. T. (2013)
  • Urquhart, Andrew; Mondo, Stephen; Mäkelä, Miia Riitta; Hane, James; Wiebenga, Ad; He, Guifen; Mihaltcheva, Sirma; Pangilinan, Jasmyn; Lipzen, Anna; Barry, Kerrie; de Vries, Ronald; Grigoriev, Igor V.; Idnurm, Alexander (2018)
    Species in the genus Paecilomyces, a member of the fungal order Eurotiales, are ubiquitous in nature and impact a variety of human endeavors. Here, the biology of one common species, Paecilomyces variotii, was explored using genomics and functional genetics. Sequencing the genome of two isolates revealed key genome and gene features in this species. A striking feature of the genome was the two-part nature, featuring large stretches of DNA with normal GC content separated by AT-rich regions, a hallmark of many plant-pathogenic fungal genomes. These AT-rich regions appeared to have been mutated by repeat-induced point (RIP) mutations. We developed methods for genetic transformation of P. variotii, including forward and reverse genetics as well as crossing techniques. Using transformation and crossing, RIP activity was identified, demonstrating for the first time that RIP is an active process within the order Eurotiales. A consequence of RIP is likely reflected by a reduction in numbers of genes within gene families, such as in cell wall degradation, and reflected by growth limitations on P. variotii on diverse carbon sources. Furthermore, using these transformation tools we characterized a conserved protein containing a domain of unknown function (DUF1212) and discovered it is involved in pigmentation.
  • Miraldo, Andreia; Duplouy, Anne (2019)
    Determining the drivers of diversity is a major topic in biology. Due to its high level of micro-endemism in many taxa, Madagascar has been described as one of Earth's biodiversity hotspot. The exceptional Malagasy biodiversity has been shown to be the result of various eco-evolutionary mechanisms that have taken place on this large island since its isolation from other landmasses. Extensive phylogenetic analyses have, for example, revealed that most of the dung beetle radiation events have arisen due to allopatric speciation, and adaptation to altitudinal and/or longitudinal gradients. But other biotic factors, that have yet to be identified, might also be at play. Wolbachia is a maternally transmitted endosymbiotic bacterium widespread in insects. The bacterium is well-known for its ability to modify its host reproductive system in ways that may lead to either discordance patterns between the host mitochondrial and nuclear phylogenies, and in some cases to speciation. Here, we used theMultiLocus Sequence Typing system, to identify and characterize five Wolbachia strains infecting several species within the Nanos clypeatus dung beetle clade. We discuss the implications of these Wolbachia strains for the evolution and diversification of their dung beetle hosts in Madagascar.
  • Oversti, Sanni; Majander, Kerttu; Salmela, Elina; Salo, Kati; Arppe, Laura; Belskiy, Stanislav; Etu-Sihvola, Heli; Laakso, Ville; Mikkola, Esa; Pfrengle, Saskia; Putkonen, Mikko; Taavitsainen, Jussi-Pekka; Vuoristo, Katja; Wessman, Anna; Sajantila, Antti; Oinonen, Markku; Haak, Wolfgang; Schuenemann, Verena J.; Krause, Johannes; Palo, Jukka U.; Onkamo, Paivi (2019)
    Human ancient DNA studies have revealed high mobility in Europe's past, and have helped to decode the human history on the Eurasian continent. Northeastern Europe, especially north of the Baltic Sea, however, remains less well understood largely due to the lack of preserved human remains. Finland, with a divergent population history from most of Europe, offers a unique perspective to hunter-gatherer way of life, but thus far genetic information on prehistoric human groups in Finland is nearly absent. Here we report 103 complete ancient mitochondrial genomes from human remains dated to AD 300-1800, and explore mtDNA diversity associated with hunter-gatherers and Neolithic farmers. The results indicate largely unadmixed mtDNA pools of differing ancestries from Iron-Age on, suggesting a rather late genetic shift from hunter-gatherers towards farmers in North-East Europe. Furthermore, the data suggest eastern introduction of farmer-related haplogroups into Finland, contradicting contemporary genetic patterns in Finns.
  • Pessi, Igor S.; Viitamäki, Sirja; Virkkala, Anna-Maria; Eronen-Rasimus, Eeva; Delmont, Tom O.; Marushchak, Maija E.; Luoto, Miska; Hultman, Jenni (2022)
    Background In contrast to earlier assumptions, there is now mounting evidence for the role of tundra soils as important sources of the greenhouse gas nitrous oxide (N2O). However, the microorganisms involved in the cycling of N2O in this system remain largely uncharacterized. Since tundra soils are variable sources and sinks of N2O, we aimed at investigating differences in community structure across different soil ecosystems in the tundra. Results We analysed 1.4 Tb of metagenomic data from soils in northern Finland covering a range of ecosystems from dry upland soils to water-logged fens and obtained 796 manually binned and curated metagenome-assembled genomes (MAGs). We then searched for MAGs harbouring genes involved in denitrification, an important process driving N2O emissions. Communities of potential denitrifiers were dominated by microorganisms with truncated denitrification pathways (i.e., lacking one or more denitrification genes) and differed across soil ecosystems. Upland soils showed a strong N2O sink potential and were dominated by members of the Alphaproteobacteria such as Bradyrhizobium and Reyranella. Fens, which had in general net-zero N2O fluxes, had a high abundance of poorly characterized taxa affiliated with the Chloroflexota lineage Ellin6529 and the Acidobacteriota subdivision Gp23. Conclusions By coupling an in-depth characterization of microbial communities with in situ measurements of N2O fluxes, our results suggest that the observed spatial patterns of N2O fluxes in the tundra are related to differences in the composition of denitrifier communities.
  • Weitschek, Emanuel; Cunial, Fabio; Felici, Giovanni (2015)
    Alignment-free algorithms can be used to estimate the similarity of biological sequences and hence are often applied to the phylogenetic reconstruction of genomes. Most of these algorithms rely on comparing the frequency of all the distinct substrings of fixed length (k-mers) that occur in the analyzed sequences. In this paper, we present Logic Alignment Free (LAF), a method that combines alignment-free techniques and rule-based classification algorithms in order to assign biological samples to their taxa. This method searches for a minimal subset of k-mers whose relative frequencies are used to build classification models as disjunctive-normal-form logic formulas (if-then rules). We apply LAF successfully to the classification of bacterial genomes to their corresponding taxonomy. In particular, we succeed in obtaining reliable classification at different taxonomic levels by extracting a handful of rules, each one based on the frequency of just few k-mers. State of the art methods to adjust the frequency of k-mers to the character distribution of the underlying genomes have negligible impact on classification performance, suggesting that the signal of each class is strong and that LAF is effective in identifying it.
  • Bourdais, Gildas; Burdiak, Pawel; Gauthier, Adrien Guy Bernard; Nitsch, Lisette; Salojärvi, Jarkko Tapani; Rayapuram, Channabasavangowda; Idänheimo, Niina Johanna; Hunter, Kerri Alyssa; Kimura, Sachie; Merilo, Ebe; Vaattovaara, Aleksia Fanni Maria; Oracz, Krystyna; Kaufholdt, David; Pallon, Andres; Anggoro, Damar Tri; Glow, Dawid; Lowe, Jennifer; Zhou, Ji; Safronov, Omid; Puukko, Tuomas; Albert, Andreas; Lang, Hans; Ernst, Dieter; Kollist, Hannes; Brosche, Mikael Johan; Durner, Jörg; Borst, Jan Willem; Collinge, David B.; Karpinski, Stanislaw; Lyngkjaer, Michael F.; Robatzek, Silke; Wrzaczek, Michael Alois; Kangasjärvi, Jaakko Sakari (2015)
    Cysteine-rich receptor-like kinases (CRKs) are transmembrane proteins characterized by the presence of two domains of unknown function 26 (DUF26) in their ectodomain. The CRKs form one of the largest groups of receptor-like protein kinases in plants, but their biological functions have so far remained largely uncharacterized. We conducted a large-scale phenotyping approach of a nearly complete crk T-DNA insertion line collection showing that CRKs control important aspects of plant development and stress adaptation in response to biotic and abiotic stimuli in a non-redundant fashion. In particular, the analysis of reactive oxygen species (ROS)-related stress responses, such as regulation of the stomatal aperture, suggests that CRKs participate in ROS/redox signalling and sensing. CRKs play general and fine-tuning roles in the regulation of stomatal closure induced by microbial and abiotic cues. Despite their great number and high similarity, large-scale phenotyping identified specific functions in diverse processes for many CRKs and indicated that CRK2 and CRK5 play predominant roles in growth regulation and stress adaptation, respectively. As a whole, the CRKs contribute to specificity in ROS signalling. Individual CRKs control distinct responses in an antagonistic fashion suggesting future potential for using CRKs in genetic approaches to improve plant performance and stress tolerance.
  • Brozzo, Alissa; Harl, Josef; De Mattia, Willy; Teixeira, Dinarte; Walther, Frank; Groh, Klaus; Pall-Gergely, Barna; Glaubrecht, Matthias; Hausdorf, Bernhard; Neiber, Marco T. (2020)
    The Geomitrini is the most species-rich group of land snails in the Madeiran Archipelago. The phylogeny of the group is reconstructed based on mitochondrial and nuclear genetic markers. The timing of diversification, the colonisation history of the islands of the Madeiran Archipelago and the evolution of characters of the dart apparatus are studied. The results of the phylogenetic analyses confirm the sister group relationship of Geomitrini and Cochlicellini, but also show that several previously accepted genus-group taxa are not monophyletic. A new classification for the Geomitrini is proposed, including the description of two new genera, Domunculifex Brozzo, De Mattia, Harl & Neiber, n. gen. and Testudodiscula Brozzo, De Mattia, Harl & Neiber, n. gen. The onset of diversification of Geomitrini was dated in our analysis at 13 Ma, which largely coincides with the emergence of the present-day islands. The ancestral state estimation recovered the presence of two appendiculae in the reproductive system as the ancestral state in Geomitrini. One appendicula was lost three times independently within the tribe and is even missing completely in one group. The ancestral area estimation suggests recurrent colonisations of Madeira (and the Ilhas Desertas) from the older island Porto Santo.
  • Mizuno, Carolina M.; Prajapati, Bina; Lucas-Staat, Soizick; Sime-Ngando, Telesphore; Forterre, Patrik; Bamford, Dennis Henry; Prangishvili, David; Krupovic, Mart; Oksanen, Hanna Maarit (2019)
    The diversity of archaeal viruses is severely undersampled compared with that of viruses infecting bacteria and eukaryotes, limiting our understanding on their evolution and environmental impacts. Here, we describe the isolation and characterization of four new viruses infecting halophilic archaea from the saline Lake Retba, located close to Dakar on the coast of Senegal. Three of the viruses, HRPV10, HRPV11 and HRPV12, have enveloped pleomorphic virions and should belong to the family Pleolipoviridae, whereas the forth virus, HFTV1, has an icosahedral capsid and a long non-contractile tail, typical of bacterial and archaeal members of the order Caudovirales. Comparative genomic and phylogenomic analyses place HRPV10, HRPV11 and HRPV12 into the genus Betapleolipovirus, whereas HFTV1 appears to be most closely related to the unclassified Halorubrum virus HRTV-4. Differently from HRTV-4, HFTV1 encodes host-derived minichromosome maintenance helicase and PCNA homologues, which are likely to orchestrate its genome replication. HFTV1, the first archaeal virus isolated on a Haloferax strain, could also infect Halorubrum sp., albeit with an eightfold lower efficiency, whereas pleolipoviruses nearly exclusively infected autochthonous Halorubrum strains. Mapping of the metagenomic sequences from this environment to the genomes of isolated haloarchaeal viruses showed that these known viruses are underrepresented in the available viromes.
  • Jike, Wuhe; Li, Mingai; Zadra, Nicola; Barbaro, Enrico; Sablok, Gaurav; Bertorelle, Giorgio; Rota-Stabelli, Omar; Varotto, Claudio (2020)
    Polyploidization is a frequent phenomenon in plants, which entails the increase from one generation to the next by multiples of the haploid number of chromosomes. While tetraploidization is arguably the most common and stable outcome of polyploidization, over evolutionary time triploids often constitute only a transient phase, or a "triploid bridge", between diploid and tetraploid levels. In this study, we reconstructed in a robust phylogenomic and statistical framework the evolutionary history of polyploidization inArundo, a small genus from the Poaceae family with promising biomass, bioenergy and phytoremediation species. Through the obtainment of 10 novel leaf transcriptomes forArundoand outgroup species, our results prove that recurrent demiduplication has likely been a major driver of evolution in this species-poor genus. Molecular dating further demonstrates that the species originating by demiduplication stalled in the "triploid bridge" for evolutionary times in the order of millions of years without undergoing tetratploidization. Nevertheless, we found signatures of molecular evolution highlighting some of the processes that accompanied the genus radiation. Our results clarify the complex nature ofArundoevolution and are valuable for future gene functional validation as well as reverse and comparative genomics efforts in theArundogenus and other Arundinoideae.
  • Löytynoja, Ari (Humana press, 2021)
    Methods in Molecular Biology
    Evolutionary analyses require sequence alignments that correctly represent evolutionary homology. Evolutionary homology and proteins' structural similarity are not the same and sequence alignments generated with methods designed for structural matching can be seriously misleading in comparative and phylogenetic analyses. The phylogeny-aware alignment algorithm implemented in the program PRANK has been shown to produce good alignments for evolutionary inferences. Unlike other alignment programs, PRANK makes use of phylogenetic information to distinguish alignment gaps caused by insertions or deletions and, thereafter, handles the two types of events differently. As a by-product of the correct handling of insertions and deletions, PRANK can provide the inferred ancestral sequences as a part of the output and mark the alignment gaps differently depending on their origin in insertion or deletion events. As the algorithm infers the evolutionary history of the sequences, PRANK can be sensitive to errors in the guide phylogeny and violations on the underlying assumptions about the origin and patterns of gaps. To mitigate the effects of such model violations, the phylogeny-aware alignment algorithm has been re-implemented in program PAGAN. By using sequence graphs, PAGAN can model and accumulate evidence from more complex gap structures than PRANK does, and incorporate this uncertainty in the inferred ancestral sequences. These issues are discussed in detail below and practical advice is provided for the use of PRANK and PAGAN in evolutionary analysis. The two software packages can be downloaded from
  • Leavitt, Steven D.; Lumbsch, H. Thorsten; Stenroos, Soili; St Clair, Larry L. (2013)
    Pleistocene climatic fluctuations influenced patterns of genetic variation and promoted speciation across a wide range of species groups. Lichens are commonly found in habitats that were directly impacted by glacial cycles; however, the role of Pleistocene climate in driving speciation in most lichen symbionts remains unclear. This uncertainty is due in part to limitations in our ability to accurately recognize independently evolving lichen-forming fungal lineages and a lack of relevant fossil calibrations. Using a coalescent-based species tree approach, we estimated divergence times for two sister clades in the genus Xanthoparmelia (Parmeliaceae) restricted to western North America. We assessed the influence of two different species circumscription scenarios and various locus-specific rates of molecular evolution on divergence estimates. Species circumscriptions were validated using the program BP&P. although speciation was generally supported in both scenarios, divergence times differed between traditional species circumscriptions and those based on genetic data, with more recent estimates resulting from the former. Similarly, rates of evolution for different loci resulted in variable divergence time estimates. However, our results unambiguously indicate that diversification in the sampled Xanthoparmelia clades occurred during the Pleistocene. Our study highlights the potential impact of ambiguous species circumscriptions and uncertain rates of molecular evolution on estimating divergence times within a multilocus species tree framework