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- Fedorov, Vadim B.
(författare)
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Phylogeography and mitochondrial DNA diversity in arctic lemmings
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this thesis is to evaluate the effects of Quaternary environmental fluctuations on the present patterns of mitochondrial DNA variation in the wood lemming, Myopus schisticolor, and the two genera of Arctic lemmings: collared lemmings, Dicrostonyx, and true lemmings, Lemmus.The phylogeographic pattern and the limited mtDNA diversity in the Scandinavian populations of the wood lemming reflect recent colonization by a limited number of founders during the Holocene boreal forest expansion.The mtDNA phylogeny in the two genera of Arctic lemmings gives no support for the existence of a single Beringian refungium since the mid Pleistocene. Isolation by intermittent inundation of the Bering Strait during the interglacials was most probably important for speciation in both genera, Dicrostonyx and Lemmus.Comparative phylogeography of the two genera of Arctic lemmings, Lemmus and Dicrostonyx gives evidence for the vicariant separation by the glacial barriers in the Eurasian Arctic. There is genetic support for the importance of the Asian Beringia as a refugial area for the tundra specialist, D. torquatus, during warming periods in the interglacials.There is no evidence for the direct effect of the last glaciation on the present level of mtDNA diversity and population structure in Arctic lemmings. Intrapopulation and intraregion mtDNA diversity estimates in each genus reflect the demographic events which were likely a result of environmental changes in the Holocene. Comparisons of mtDNA diversity estimates across the two genera of Arctic lemmings suggest that historically and presently codistributed Lemmus and Dicrostonyx responded differently to environmental changes resulting from the Holocene warming events in the Eurasian Arctic.The mtDNA phylogeny supports the importance of vicariant events generated by the glacial-interglacial periods for allopatric speciation in chromosomally variable collared lemmings, Dicrostonyx, in the North America Arctic. In the Eurasian Arctic, the congruence between the phylogeographic structure in mtDNA variation and geographic distribution of chromosome races indicates that the fragmentation by the glacial barriers during the late Pleistocene and bottleneck events due to warming events in the Holocene were important for the origin of intraspecific chromosome races in the collared lemming, D. torquatus
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- Goropashnaya, Anna V., et al.
(författare)
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Phylogenetic relationships of Palaearctic Formica species (Hymenoptera, Formicidae) based on mitochondrial cytochrome b sequences
- 2012
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:7, s. e41697-
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Tidskriftsartikel (refereegranskat)abstract
- Ants of genus Formica demonstrate variation in social organization and represent model species for ecological, behavioral, evolutionary studies and testing theoretical implications of the kin selection theory. Subgeneric division of the Formica ants based on morphology has been questioned and remained unclear after an allozyme study on genetic differentiation between 13 species representing all subgenera was conducted. In the present study, the phylogenetic relationships within the genus were examined using mitochondrial DNA sequences of the cytochrome b and a part of the NADH dehydrogenase subunit 6. All 23 Formica species sampled in the Palaearctic clustered according to the subgeneric affiliation except F. uralensis that formed a separate phylogenetic group. Unlike Coptoformica and Formica s. str., the subgenus Serviformica did not form a tight cluster but more likely consisted of a few small clades. The genetic distances between the subgenera were around 10%, implying approximate divergence time of 5 Myr if we used the conventional insect divergence rate of 2% per Myr. Within-subgenus divergence estimates were 6.69% in Serviformica, 3.61% in Coptoformica, 1.18% in Formica s. str., which supported our previous results on relatively rapid speciation in the latter subgenus. The phylogeny inferred from DNA sequences provides a necessary framework against which the evolution of social traits can be compared. We discuss implications of inferred phylogeny for the evolution of social traits.
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- Goropashnaya, Anna V., et al.
(författare)
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Phylogeography and population structure in the ant Formica exsecta (Hymenoptera, Formicidae) across Eurasia as reflected by mitochondrial DNA variation and microsatellites
- 2007
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Ingår i: Annales Zoologici Fennici. - 0003-455X .- 1797-2450. ; 44:6, s. 462-474
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Tidskriftsartikel (refereegranskat)abstract
- Phylogeography and population structure of the ant Formica exsecta was studied across Eurasia by using mtDNA sequences and microsatellite genotypes. The phylogeny based on 1.5 kb mtDNA fragment including the cytochrome b and part of the ND6 gene showed significant division (1.63% of nucleotide divergence) between a haplotype from Tibet and all other haplotypes. Similar to findings in diverse array of species associated with forest in Eurasia, the mtDNA phylogeny revealed no evidence for vicariant events due to separation in different forest refugia over glacial periods. The haplotype network includes several small clades (with 2-4 haplotypes in each) with geographically limited distribution, but one geographical region may have received haplotypes from two or more of such clades. This pattern could indicate mixing of different gene pools during postglacial colonization of Europe from different forest refugia or from an ancestral source with some spatial genetic differentiation. The genealogy and the haplotype frequencies suggest postglacial colonization of Siberia from a single refugial source of limited size. Maternal and biparental DNA markers indicated a moderate but significant level of population differentiation (mtDNA Phi(ST) = 0.42, microsatellite F-ST = 0.13) across Eurasia. However, no correlation between genetic differentiation estimated for mtDNA and microsatellites was found among the populations. Considerable reduction in microsatellite genetic diversity was found in the small population of F. exsecta in England, giving some basis to classify this population as near threatened.
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- Goropashnaya, Anna V, et al.
(författare)
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Recent speciation in the Formica rufa group ants (Hymenoptera, Formicidae) : inference from mitochondrial DNA phylogeny
- 2004
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Ingår i: Molecular Phylogenetics and Evolution. - : Elsevier BV. - 1055-7903 .- 1095-9513. ; 32:1, s. 198-206
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Tidskriftsartikel (refereegranskat)abstract
- This study examines phylogenetic relationships among six species of the Formica rufa group ants (F. polyctena, F. rufa, F. lugubris, F. paralugubris, F. aquilonia, and F. pratensis). The phylogeny based on a 2051bp fragment of mtDNA including cyt b, tRNASer, and ND1 genes supports the division of the group into three major clusters: one with the species F. polyctena and F. rufa, one with F. aquilonia, F. lugubris, and F. paralugubris, and the third one with F. pratensis. The interspecific divergence estimates (mean 0.98 +/- 0.15% for the main phylogenetic groups) imply that radiation took place during the Pleistocene. Comparison of the divergence estimates among the F. rufa group species with divergence estimates among other closely related species of insects suggests that speciation in the group was relatively fast, and the mitochondrial lineages of F. polyctena and F. rufa have not fully separated. The haplotype tree shows also signs of transfer of mtDNA between species through hybridisation. The distribution of polygyny (multiple queens per nest) along the branches of the tree indicates that the social type characterised by highly polygynous societies and large colonial networks, has originated at least three times. The species F. aquilonia and F. paralugubris that build such large supercolonies, cluster tightly together with very little nucleotide variation, suggesting that this type of social organisation could be a factor promoting speciation in the ants.
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- Lewis, Christopher T. A., et al.
(författare)
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Remodeling of skeletal muscle myosin metabolic states in hibernating mammals
- 2024
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Ingår i: eLIFE. - : eLife Sciences Publications Ltd. - 2050-084X. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Hibernation is a period of metabolic suppression utilized by many small and large mammal species to survive during winter periods. As the underlying cellular and molecular mechanisms remain incompletely understood, our study aimed to determine whether skeletal muscle myosin and its metabolic efficiency undergo alterations during hibernation to optimize energy utilization. We isolated muscle fibers from small hibernators, Ictidomys tridecemlineatus and Eliomys quercinus and larger hibernators, Ursus arctos and Ursus americanus. We then conducted loaded Mant-ATP chase experiments alongside X-ray diffraction to measure resting myosin dynamics and its ATP demand. In parallel, we performed multiple proteomics analyses. Our results showed a preservation of myosin structure in U. arctos and U. americanus during hibernation, whilst in I. tridecemlineatus and E. quercinus, changes in myosin metabolic states during torpor unexpectedly led to higher levels in energy expenditure of type II, fast-twitch muscle fibers at ambient lab temperatures (20 °C). Upon repeating loaded Mant-ATP chase experiments at 8 °C (near the body temperature of torpid animals), we found that myosin ATP consumption in type II muscle fibers was reduced by 77-107% during torpor compared to active periods. Additionally, we observed Myh2 hyper-phosphorylation during torpor in I. tridecemilineatus, which was predicted to stabilize the myosin molecule. This may act as a potential molecular mechanism mitigating myosin-associated increases in skeletal muscle energy expenditure during periods of torpor in response to cold exposure. Altogether, we demonstrate that resting myosin is altered in hibernating mammals, contributing to significant changes to the ATP consumption of skeletal muscle. Additionally, we observe that it is further altered in response to cold exposure and highlight myosin as a potentially contributor to skeletal muscle non-shivering thermogenesis.
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| 9. |
- Lewis, Christopher T. A., et al.
(författare)
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Remodelling of skeletal muscle myosin metabolic states in hibernating mammals
- 2023
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Hibernation is a period of metabolic suppression utilized by many small and large mammal species to survive during winter periods. As the underlying cellular and molecular mechanisms remain incompletely understood, our study aimed to determine whether skeletal muscle myosin and its metabolic efficiency undergo alterations during hibernation to optimize energy utilization. We isolated muscle fibers from small hibernators, Ictidomys tridecemlineatus and Eliomys quercinus and larger hibernators, Ursus arctos and Ursus americanus. We then conducted loaded Mant-ATP chase experiments alongside X-ray diffraction to measure resting myosin dynamics and its ATP demand. In parallel, we performed multiple proteomics analyses. Our results showed a preservation of myosin structure in U. arctos and U. americanus during hibernation, whilst in I. tridecemlineatus and E. quercinus, changes in myosin metabolic states during torpor unexpectedly led to higher levels in energy expenditure of type II, fast-twitch muscle fibers at ambient lab temperatures (20°C). Upon repeating loaded Mant-ATP chase experiments at 8°C (near the body temperature of torpid animals), we found that myosin ATP consumption in type II muscle fibers was reduced by 77-107% during torpor compared to active periods. Additionally, we observed Myh2 hyper-phosphorylation during torpor in I. tridecemilineatus, which was predicted to stabilize the myosin molecule. This may act as a potential molecular mechanism mitigating myosin-associated increases in skeletal muscle energy expenditure during periods of torpor in response to cold exposure. Altogether, we demonstrate that resting myosin is altered in hibernating mammals, contributing to significant changes to the ATP consumption of skeletal muscle. Additionally, we observe that it is further altered in response to cold exposure and highlight myosin as a potentially contributor to skeletal muscle non-shivering thermogenesis.
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