| 1. |
- Speakman, John R., et al.
(författare)
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Total daily energy expenditure has declined over the past three decades due to declining basal expenditure, not reduced activity expenditure
- 2023
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Ingår i: Nature Metabolism. - : NATURE PORTFOLIO. - 2522-5812. ; 5:4, s. 579-588
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Obesity is caused by a prolonged positive energy balance(1,2). Whether reduced energy expenditure stemming from reduced activity levels contributes is debated(3,4). Here we show that in both sexes, total energy expenditure (TEE) adjusted for body composition and age declined since the late 1980s, while adjusted activity energy expenditure increased over time. We use the International Atomic Energy Agency Doubly Labelled Water database on energy expenditure of adults in the United States and Europe (n = 4,799) to explore patterns in total (TEE: n = 4,799), basal (BEE: n = 1,432) and physical activity energy expenditure (n = 1,432) over time. In males, adjusted BEE decreased significantly, but in females this did not reach significance. A larger dataset of basal metabolic rate (equivalent to BEE) measurements of 9,912 adults across 163 studies spanning 100 years replicates the decline in BEE in both sexes. We conclude that increasing obesity in the United States/Europe has probably not been fuelled by reduced physical activity leading to lowered TEE. We identify here a decline in adjusted BEE as a previously unrecognized factor.
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| 2. |
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| 3. |
- Castroviejo-Fisher, Santiago, 1979-
(författare)
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Species Limits, and Evolutionary History of Glassfrogs
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Recognizing the mechanisms of speciation and the limits of species is essential to understand the origin of biodiversity and how to conserve it. The general aims of my investigations during my doctoral studies were two-fold: to study evolutionary patterns and processes, and to provide specific and superspecific taxonomic classifications that try to reflect evolutionary history. I have focused my research on anurans in their biodiversity hotspot, the American Tropics. I have used morphological, behavioral (mating calls), and genetic (DNA sequences) characters to study species boundaries between frogs of the genus Pristimantis and the family Centrolenidae (glassfrogs). The results show that the exclusive use of single lines of evidence or the application of arbitrary thresholds impair and bias our ability to recognize new species and limit the possibility to understand evolutionary processes. Only an integrative approach combining every source of evidence provides the necessary feedback to discover all species and test their identity by comparing independent sets of data. This approach further allows identifying those species that probably represent stable comparative units (well supported species hypotheses) and to flag taxa that require further assessment. Phylogenetic reconstructions based on seven nuclear and mitochondrial genes for about 100 species of glassfrogs revealed that previous hypotheses of relationships were mislead by rampant convergent evolution at the phenotypic level. None of the previously suggested classifications fit with the reconstructed evolutionary history. Consequently, we proposed a new classification consistent with this phylogeny. I also studied the tempo and mode of diversification among glassfrogs. Based on sequences from ten genes in 87 species, I estimated species divergence times, age-range correlation between sister species, and reconstructed ancestral areas and dispersal/vicariance events. The results revealed a complex model of diversification where geographical isolation seems to be the dominant scenario for speciation and only clades of altitudinal generalists have been able to spread across the Neotropical rainforests.
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| 5. |
- den Tex, Robert-Jan, 1969-
(författare)
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Patterns and Processes of Evolution in Sundaland
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Biodiversity in the tropics is disproportionately high compared to other habitats, and also under disproportionate threat from human impact. It is necessary to understand how this diversity evolved and how it is partitioned across space in order to preserve it. In this thesis I construct phylogenies of tropical forest dependent vertebrates from Southeast Asia and the islands of the Sunda shelf, a region referred to as Sundaland. I focus on the tree squirrels (genus Sundasciurus) and Asian barbets (Aves: Family Megalaimidae), two taxa with similar ecological characteristics. I use these phylogenies to test hypotheses that have been put forward to explain high levels of tropical diversity including the Pleistocene pump and museum hypotheses. I also use phylogenies to elucidate phylogeographic patterns within the region. I find no evidence for an increase in speciation in the Pleistocene, but I do find within species structure that dates to this period. Common phylogeographic patterns were identified between many forest dependent vertebrates that suggest that populations on the island of Sumatra are generally more closely related to Malay Peninsula populations than to populations on Borneo. From a methodological viewpoint we propose careful usage of universal primers in ancient DNA studies because of our finding of increased risk of amplifying pseudogenes of the mtDNA.
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| 8. |
- Ersmark, Erik, 1977-
(författare)
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Large carnivore population turnover and ecological change during the Late Quaternary
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The cave lion (Panthera spelaea), the grey wolf (Canis lupus) and the brown bear (Ursus arctos) all shared an intercontinental distribution across the northern hemisphere during most of the Late Quaternary, and experienced repeated events of climate change. The cave lion went extinct at the end of the Pleistocene and although the wolf and the bear have survived until present day, recent human persecution has caused demographic bottlenecks and local extinctions. In this thesis, mitochondrial and nuclear DNA was analyzed from ancient and modern samples in order to study spatiotemporal changes in genetic diversity in the three species. Mitochondrial sequences analyzed from 48 radiocarbon dated cave lion remains revealed two haplogroups, of which the more genetically diverse seemingly disappeared around 41,000 years BP. Serial coalescent simulations on the data supported a population bottleneck in Beringia between roughly 47-18,000 years BP. Its long duration prevents a specific causal factor to be singled out, but the early onset and overlapping declines of other large mammals in the region suggests that major environmental changes greatly impacted the fauna of Beringia during this time. Using a similar genetic marker, a set of 126 modern wolves and two Siberian wolf remains of Late Pleistocene age were analyzed. The sequences yielded from the latter samples pertained to a basal haplogroup, which contained all Late Pleistocene wolves from previous studies. As data from both modern and ancient wolves were combined, a pattern of decreasing genetic diversity was identified around the Pleistocene-Holocene transition. This decrease was further tested by serial coalescent simulations, which supported a bottleneck in northern North America around this time. Further analyses were applied to one of the ancient wolf remains from Siberia, producing a draft genome sequence and a complete mitochondrial genome. Given the radiocarbon date of the Siberian wolf, a slower mutation rate could be inferred, which pushed back the split between the lineages leading to modern wolves and dogs to at least 27,000 years BP. The Siberian wolf was positioned close to the split but basal to these lineages. A global comparison with modern dogs indicated a closer genetic affiliation between the Siberian wolf and some arctic breeds. For the brown bear, phylogeographic changes in Europe were studied over the last 50,000 years, using radiocarbon dating and mitochondrial sequences. When concatenated and compared with published data, the mtDNA revealed a turnover event just before the LGM, while the dating confirmed a presence of brown bears at relatively high latitudes during this period. Marked shifts in population size were also inferred. Furthermore, data of stable isotope levels confirmed a dietary shift to increasing herbivory around the LGM. Finally, a recent anthropogenic bottleneck among Scandinavian brown bears was studied. While no change in genetic structure could be detected, mitochondrial and microsatellite markers showed a decline in genetic diversity, especially pronounced in the southern subpopulation. ABC simulations supported a bottleneck taking place across all of Scandinavia. Taken together, this thesis have identified and elucidated several impacts on genetic diversity in the past populations of large carnivores. The use of different genetic markers has enabled comparisons with published data, but also revealed their comparatively different benefits and limitations. Overall, the presented studies compose a synthesis of past population dynamics in large carnivores, uniquely revealed by ancient DNA.
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| 9. |
- Koblmüller, Stephan, et al.
(författare)
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More is Better
- 2009
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Ingår i: Molecular Ecology. - 0962-1083 .- 1365-294X. ; 18:24, s. 4994-4996
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 10. |
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