Browsing by Subject "ISLANDS"

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  • Vizueta, Joel; Macias-Hernandez, Nuria; Arnedo, Miguel A.; Rozas, Julio; Sanchez-Gracia, Alejandro (2019)
    The coexistence of multiple eco-phenotypes in independently assembled communities makes island adaptive radiations the ideal framework to test convergence and parallelism in evolution. In the radiation of the spider genus Dysdera in the Canary Islands, species diversification occurs concomitant with repeated events of trophic specialization. These dietary shifts, to feed primarily on woodlice, are accompanied by modifications in morphology (mostly in the mouthparts), behaviour and nutritional physiology. To gain insight into the molecular basis of this adaptive radiation, we performed a comprehensive comparative transcriptome analysis of five Canary Island Dysdera endemics representing two evolutionary and geographically independent events of dietary specialization. After controlling for the potential confounding effects of hemiplasy, our differential gene expression and selective constraint analyses identified a number of genetic changes that could be associated with the repeated adaptations to specialized diet of woodlice, including some related to heavy metal detoxification and homeostasis, the metabolism of some important nutrients and venom toxins. Our results shed light on the genomic basis of an extraordinary case of dietary shift convergence associated with species diversification. We uncovered putative molecular substrates of convergent evolutionary changes at different hierarchical levels, including specific genes, genes with equivalent functions and even particular amino acid positions. This study improves our knowledge of rapid adaptive radiations and provides new insights into the predictability of evolution.
  • Mishra, Pashupati P.; Hänninen, Ismo; Raitoharju, Emma; Marttila, Saara; Mishra, Binisha H.; Mononen, Nina; Kähönen, Mika; Hurme, Mikko; Raitakari, Olli; Törönen, Petri; Holm, Liisa; Lehtimaki, Terho (2020)
    Smoking as a major risk factor for morbidity affects numerous regulatory systems of the human body including DNA methylation. Most of the previous studies with genome-wide methylation data are based on conventional association analysis and earliest threshold-based gene set analysis that lacks sensitivity to be able to reveal all the relevant effects of smoking. The aim of the present study was to investigate the impact of active smoking on DNA methylation at three biological levels: 5'-C-phosphate-G-3' (CpG) sites, genes and functionally related genes (gene sets). Gene set analysis was done with mGSZ, a modern threshold-free method previously developed by us that utilizes all the genes in the experiment and their differential methylation scores. Application of such method in DNA methylation study is novel. Epigenome-wide methylation levels were profiled from Young Finns Study (YFS) participants' whole blood from 2011 follow-up using Illumina Infinium Hu-manMethylation450 BeadChips. We identified three novel smoking related CpG sites and replicated 57 of the previously identified ones. We found that smoking is associated with hypomethylation in shore (genomic regions 0-2 kilobases from CpG island). We identified smoking related methylation changes in 13 gene sets with false discovery rate (FDR)
  • Sessa, Emily B.; Juslen, Aino; Väre, Henry; Chambers, Sally M. (2017)
    PREMISE OF THE STUDY: Our goal was to infer the phylogenetic relationships and historical biogeography of the genus Dryopteris with a focus on taxa in sub-Saharan Africa and neighboring islands. In general, little is known about the relationships between African fern species and their congeners in other geographic regions, and our aim was to determine whether the sub-Saharan African species of Dryopteris are monophyletic and evolved within Africa or arrived there via repeated dispersals into Africa from other regions. METHODS: We obtained sequence data for five chloroplast markers from 214 species of Dryopteris and 18 outgroups. We performed phylogenetic and molecular dating analyses using a Bayesian relaxed clock method in BEAST with fossil and secondary calibration points and estimated ancestral ranges for the genus globally by comparing multiple models in BioGeoBEARS. KEY RESULTS: We found that 22 of 27 accessions of sub-Saharan African Dryopteris belong to a large clade of 31 accessions that also includes taxa from Indian and Atlantic Ocean islands. Additional accessions of taxa from our regions of interest have Asian, Hawaiian, European, or North American species as their closest relatives. CONCLUSIONS: The majority of sub-Saharan African Dryopteris species are descended from a shared common ancestor that dispersed to Africa from Asia approximately 10 Ma. There have been subsequent dispersal events from the African mainland to islands in the Atlantic and Indian Oceans, including Madagascar. Several additional species are estimated to have descended from ancestors that reached Africa via separate events over the last roughly 20 million years.
  • Melvin, Richard G.; Lamichane, Nicole; Havula, Essi; Kokki, Krista; Soeder, Charles; Jones, Corbin D.; Hietakangas, Ville (2018)
    How dietary selection affects genome evolution to define the optimal range of nutrient intake is a poorly understood question with medical relevance. We have addressed this question by analyzing Drosophila simulans and sechellia, recently diverged species with differential diet choice. D. sechellia larvae, specialized to a nutrient scarce diet, did not survive on sugar-rich conditions, while the generalist species D. simulans was sugar tolerant. Sugar tolerance in D. simulans was a tradeoff for performance on low-energy diet and was associated with global reprogramming of metabolic gene expression. Hybridization and phenotype-based introgression revealed the genomic regions of D. simulans that were sufficient for sugar tolerance. These regions included genes that are involved in mitochondrial ribosome biogenesis and intracellular signaling, such as PPP1R15/Gadd34 and SERCA, which contributed to sugar tolerance. In conclusion, genomic variation affecting genes involved in global metabolic control defines the optimal range for dietary macronutrient composition.
  • Daneliya, Mikhail (2021)
    The mysid fauna of the Tasman Sea and its Australian coast, in particular, is barely known. The first special study of the subfamily Heteromysinae (family Mysidae) in the waters of New South Wales, based on the collections in the Australian Museum, yielded seven species of the genus Heteromysis (tribe Heteromysini). The Tasman Sea species of Heteromysis are distributed among three subgenera: Heteromysis s. str., Gnathomysis and Olivemysis. New species of Heteromysis include H. (H.) keablei, sp. nov. and H. (O.) murrayae sp. nov. The Tasman Sea members of the subgenus Heteromysis s. str., together with a number of other congeners, form a group of species with a particular structure of the pereopod 1 endopod and antennulae. Comparative review of the species of Heteromysis resulted in species rearrangement of another Heteromysini member, the genus Heteromysoides (for which a type species is fixed herein), with its species divided between Heteromysis, Platyops and Deltamysis (the tribe Mysidetini). Platyops is transferred to Heteromysini.
  • Tonteri, E.; Kurkela, S.; Timonen, S.; Manni, T.; Vuorinen, T.; Kuusi, M.; Vapalahti, O. (2015)
    The geographical risk areas for tick-borne encephalitis (TBE) in Finland remained the same until the beginning of the 21st century, but a considerable geographical expansion has been observed in the past 10 years. In order to support public health measures, the present study describes the number of laboratory-confirmed TBE cases and laboratory tests conducted and the associated trends by hospital district, with a particular emphasis on the suspected geographical risk areas. An additional investigation was conducted on 1,957 clinical serum samples throughout the country taken from patients with neurological symptoms to screen for undiagnosed TBE cases. This study identified new TBE foci in Finland, reflecting the spread of the disease into new areas. Even in the most endemic municipalities, transmission of TBE to humans occurred in very specific and often small foci. The number of antibody tests for TBE virus more than doubled (an increase by 105%) between 2007 and 2013. Analysis of the number of tests also revealed areas in which the awareness of clinicians may be suboptimal at present. However, it appears that underdiagnosis of neuroinvasive TBE is not common.
  • Yrjölä, Rauno A.; Holopainen, Sari; Pakarinen, Raimo; Tuoriniemi, Sini; Luostarinen, Matti; Mikkola-Roos, Markku; Nummi, Petri; Väänänen, Veli-Matti (2017)
    We studied the population growth and expansion of Barnacle Goose (Branta leucopsis) in Helsinki archipelago, southern Finland. Barnacle Goose breeding was first recorded in Helsinki in 1989. During our study 1996-2013 the number of nesting geese increased from 24 to 740 pairs. We analyzed the role of protected islands in the population growth, and the factors behind differences in growth rates. Our study data consisted of 104 islands. Of these, 29 are protected from private recreational activity (nature reserve ormilitary areas) and were established prior to the start of our study. We predicted that protected areas would have a positive impact on Barnacle Goose population growth. In part of the study period (2002-2013) the population growth in our study area was much steeper in protected islands compared to islands with open access. However, breeding densities in those unprotected islands were higher than in protected islands in the early years of the study. We found that the most important factors affecting pair numbers in islands are island size and the time it has been inhabited, in addition to island distance from the islands southeast of Helsinki, where breeding expansion started. Island protection had no effect on the breeding geese numbers or current densities on the islands. Results indicate that early breeders like Barnacle Geese do not benefit from island protection probably because the recreational use of the islands is scant early in the spring.