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140 results for “Mammal Evolution”
Data from: Joint reconstruction of divergence times and life-history evolution in placental mammals using a phylogenetic covariance model
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Data from: Marine strontium isotopes preserved in fossil shark teeth calibrate Neogene land mammal evolution
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Data from: Hibernation constrains brain size evolution in mammals
The expensive brain hypothesis predicts that the lowest stable level of steady energy input acts as a strong constraint on a species' brain size, and thus that periodic troughs in net energy intake should select for reduced brain size relative to body mass. Here, we test this prediction for the extreme case of hibernation. Hibernators drastically reduce food intake for up to several months, and are therefore expected to have smaller relative brain sizes than non‐hibernating species. Using a comparative phylogenetic approach on brain size estimates of 1104 mammalian species, and controlling for possible confounding variables, we indeed found that the presence of hibernation in mammals is correlated with decreased relative brain size. This result adds to recent comparative work across mammals and amphibians supporting the idea that environmental seasonality (where in extremis hibernation is necessary for survival) imposes an energetic challenge, and thus acts as an evolutionary constraint on relative brain size.
Data from: RUNX2 tandem repeats and the evolution of facial length in placental mammals
BACKGROUND: When simple sequence repeats are integrated into functional genes, they can potentially act as evolutionary 'tuning knobs', supplying abundant genetic variation with minimal risk of pleiotropic deleterious effects. The genetic basis of variation in facial shape and length represents a possible example of this phenomenon. Runt-related transcription factor 2 (RUNX2) which is involved in osteoblast differentiation, contains a functionally-important tandem repeat of glutamine and alanine amino acids. The ratio of glutamines to alanines (the QA ratio) in this protein seemingly influences the regulation of bone development. Notably, in domestic breeds of dog, and in carnivorans in general, the ratio of glutamines to alanines is strongly correlated with facial length. RESULTS: In this study we examine whether this correlation holds true across placental mammals, particularly those mammals for which facial length is highly variable and related to adaptive behavior and lifestyle (e.g., primates, afrotherians, xenarthrans). We obtained relative facial length measurements and RUNX2 sequences for 41 mammalian species representing 12 orders. Using both a phylogenetic generalized least squares model and recently-developed Bayesian comparative method, we tested for a correlation between genetic and morphometric data while controlling for phylogeny, evolutionary rates, and divergence times. Non-carnivoran taxa generally had substantially lower glutamine-alanine ratios than carnivorans (primates and xenarthrans with means of 1.34 and 1.25, respectively, compared to a mean of 3.1 for carnivorans), and we found no correlation between RUNX2 sequence and face length across placental mammals. CONCLUSIONS: Results of our diverse comparative phylogenetic analyses indicate that QA ratio does not consistently correlate with face length across the 41 mammalian taxa considered. Thus, although RUNX2 might function as a 'tuning knob' modifying face length in carnivorans, this relationship is not conserved across mammals in general.
Data from: Impacts of genetic correlation on the independent evolution of body mass and skeletal size in mammals
Mammals show a predictable scaling relationship between limb bone size and body mass. This relationship has a genetic basis which likely evolved via natural selection but it is unclear how much the genetic correlation between these traits in turn impacts their capacity to evolve independently. We selectively bred laboratory mice for increases in tibia length independent of body mass to test the hypothesis that a genetic correlation with body mass constrains evolutionary change in tibia length. Over 14 generations we produced mean tibia length increases of 11-12% while mean body mass was unchanged in selectively bred mice and random-bred controls. Using evolutionary scenarios with different selection and quantitative genetic parameters we also found that this genetic correlation impedes the rate of evolutionary change in both traits slowing increases in tibia length while preventing decreases in body mass despite the latter's negative effect on fitness. Overall results from this ongoing selection experiment suggest that parallel evolution of relatively longer hind limbs among rodents for example in the context of strong competition for resources and niche partitioning in heterogeneous environments may have occurred very rapidly on geological timescales in spite of the genetic correlation between tibia length and body mass.
Data from: Novel and divergent genes in the evolution of placental mammals
Analysis of genome sequences within a phylogenetic context can give insight into the mode and tempo of gene and protein evolution, including inference of gene ages. This can reveal whether new genes arose on particular evolutionary lineages and were recruited for new functional roles. Here, we apply MCL clustering with all-vs-all reciprocal BLASTP to identify and phylogenetically date 'Homology Groups' amongst vertebrate proteins. Homology Groups include new genes and highly divergent duplicate genes. Focussing on the origin of the placental mammals within the Eutheria, we identify 357 novel Homology Groups that arose on the stem lineage of Placentalia, 87 of which are deduced to play core roles in mammalian biology as judged by extensive retention in evolution. We find the human homologues of novel eutherian genes are enriched for expression in preimplantation embryo, brain, and testes, and enriched for functions in keratinization, reproductive development, and the immune system.
Data from: Completeness of the eutherian mammal fossil record and implications for reconstructing mammal evolution through the Cretaceous/Paleogene mass extinction
There is a well-established discrepancy between paleontological and molecular data regarding the timing of the origin and diversification of placental mammals. Molecular estimates place interordinal diversification dates in the Cretaceous, whilst no unambiguous crown placental fossils have been found prior to the end-Cretaceous mass extinction. Here, the completeness of the eutherian fossil record through geological time is evaluated in order to assess the suggestion that a poor fossil record is largely responsible for the difference in estimates of placental origins. The completeness of fossil specimens was measured using the Character Completeness Metric, a metric that quantifies the completeness of fossil taxa as the percentage of phylogenetic characters that are available to be scored for any given taxon. Our dataset was comprised of 33 published cladistic matrices representing 445 genera, of which 333 were coded at the species-level. There was no significant difference in eutherian completeness across the Cretaceous/Palaeogene boundary. This suggests that the lack of placental mammal fossils in the Cretaceous is not due to a poor fossil record, but more likely represents a genuine absence of placental mammals in the Cretaceous. This result supports the 'explosive model' of early placental evolution, whereby placental mammals originated around the time of the Cretaceous/Palaeogene boundary and diversified soon after the event. No correlation was found between the completeness pattern observed in this study and those of previous completeness studies on birds and sauropodomorph dinosaurs, suggesting that different factors affect the preservation of these groups. No correlations were found with various isotope proxy measures, but Akaike Information Criterion analysis found that eutherian Character Completeness Metric scores were best explained by models involving the marine carbonate strontium isotope ratios (87Sr/86Sr), suggesting that the tectonic activity might play a role in controlling the completeness of the eutherian fossil record.
Global latitudinal gradients and the evolution of body size in dinosaurs and mammals
<p>Supplementary materials for Wilson et al., 'Global latitudinal gradients and the evolution of body size in dinosaurs and mammals'. </p>
Supplementary material 1 from: Williamson TE, Brusatte SL, Wilson GP (2014) The origin and early evolution of metatherian mammals: the Cretaceous record. ZooKeys 465: 1-76. https://doi.org/10.3897/zookeys.465.8178
List of taxa and characters used in phylogenetic analysis.:
Supplementary material 2 from: Williamson TE, Brusatte SL, Wilson GP (2014) The origin and early evolution of metatherian mammals: the Cretaceous record. ZooKeys 465: 1-76. https://doi.org/10.3897/zookeys.465.8178
Taxon-Character Matrix with characters ordered (TNT file).:
FIGURE 4 in Feeding in marine mammals: An integration of evolution and ecology through time
FIGURE 4. Anatomical features associated with filter feeding in crabeater seal (Lobodon carcinophaga skull, public domain image), and gray whale (Eschrichtius robustus skull, authors' work).
FIGURE 10 in Feeding in marine mammals: An integration of evolution and ecology through time
FIGURE 10. Odontoceti stem and familial level diversity through time. The group "Delphinoidea" includes Delphinidae, Monodontidae, and Phocoenidae, as well as extinct members of this crown group of uncertain phylogenetic placement. The "river dolphins" closely related to these taxa (Inioidea and Lipotidae) are plotted separately to emphasize their diversity in the fossil record compared to the present. "Ziphioidea" includes Ziphiidae and closely related stem taxa as identified by Bianucci et al. (2016). Dashed vertical lines: black, epoch boundaries; gray, age boundaries.
FIGURE 6 in Feeding in marine mammals: An integration of evolution and ecology through time
FIGURE 6. Generic level diversity of marine mammal groups through time. Dashed vertical lines: black, epoch boundaries; gray, age boundaries. All silhouettes used in Figures 6-20 are the authors' own work.
FIGURE 9 in Feeding in marine mammals: An integration of evolution and ecology through time
FIGURE 9. Mysticeti stem and familial level diversity through time. "Cetotheriidae s.l." is a paraphyletic group including all taxa that belong to crown Mysticeti but are not grouped with any of the four living families. Dashed vertical lines: black, epoch boundaries; gray, age boundaries.
FIGURE 2 in Feeding in marine mammals: An integration of evolution and ecology through time
FIGURE 2. Anatomical features associated with biting (pierce, grip-and-tear, and crushing) feeding. 1: Crushing in sea otter (Enhydra lutris skull, from Lawlor, 1979), 2: Grip-and-tear in leopard seal (Hydruga leptonyx skull, authors' work), 3: Pierce in Southern sea lion, (Otaria byronia skull, authors' work) and in Amazon river dolphin (Inia geoffrensis skull, authors' work).
FIGURE 12 in Feeding in marine mammals: An integration of evolution and ecology through time
FIGURE 12. Hypothesized ecological replacement of desmostylians (circles) by sirenians (squares) in the North Pacific Ocean. On the top, map of the localities of Tortonian age (11 Ma) where desmostylian and sirenian were recorded. On the bottom, map of the localities of Zanclean age (5 Ma) where sirenians were recorded. Desmostylia disappear from the fossil record by the end of the Tortonian (7.2 Ma) when sirenians, particularly Hydrodamalis spp., start colonizing this region, likely feeding on the same resources. Only one occurrence per genus is reported in each locality. Locality data for each occurrence of Desmostylia and Sirenia in the Tortonian and Zanclean were downloaded from PBDB (https://paleobiodb.org) using the search parameters described in Materials and Methods and then plotted on the map.
Fig. 9 in Diversity and evolution of Hunter-Schreger Band configuration in tooth enamel of perissodactyl mammals
Fig. 9. Vertical HSB configuration in Rhinocerotoidea. A. Hyracodon nebrascensis (Leidy, 1850) (STIPB M 1772); late Eocene–early Oligocene, White River Group, Toadstool Park area, Nebraska, USA. Vertical HSB in the shearing blade of the ectoloph in the right M1. Note the bifurcations of the HSB. B. Floridaceras whitei Wood, 1964 (KOE 357); early Miocene, Gilchrist County, Florida, USA. Strictly vertical HSB in the shearing blade of the ectoloph of the upper P3. C. Detail of B.
Fig. 7 in Diversity and evolution of Hunter-Schreger Band configuration in tooth enamel of perissodactyl mammals
Fig. 7. Curved HSB configuration with the typical interface in the transverse lophs of lower molars in of tapirs. A. Tapirus sinensis Owen, 1870 (MB Ma 33219); Pleistocene, Junnan, China. B. Lophiodon remensis Lemoine, 1878 (KOE 4052); middle Eocene, Geiseltal, Germany. Abbreviation: if, interface between fields of HSB.
Fig. 3 in Diversity and evolution of Hunter-Schreger Band configuration in tooth enamel of perissodactyl mammals
Fig. 3. Typical cross−ridges on the occlusal surface of the enamel band caused by vertical HSB in a lower molar of Rhinoceros sondaicus Desmarest, 1822 (KOE 71); Pleistocene, Saniran, Java. The vertical HSB are here superimposed by thick radial enamel.
Data from: The correlated evolution of antipredator defences and brain size in mammals
Mammals that possess elaborate antipredator defences such as body armour, spines and quills are usually well protected, intermediate in size, primarily insectivorous and live in simple open environments. The benefits of such defences seem clear and may relax selection on maintaining cognitive abilities that aid in vigilance and predator recognition, and their bearers may accrue extensive production and maintenance costs. Here, in this comparative phylogenetic analysis of measurements of encephalization quotient and morphological defence scores of 647 mammal species representing nearly every order, we found that as lineages evolve stronger defences, they suffer a correlated reduction in encephalization. The only exceptions were those that live in trees—a complex three-dimensional world probably requiring greater cognitive abilities. At the proximate level, because brain tissue is extremely energetically expensive to build, mammals may be trading off spending more on elaborate defences and saving by building less powerful brains. At the ultimate level, having greater defences may also reduce the need for advanced cognitive abilities for constant assessment of environmental predation risk, especially in simple open environments.
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Allen Brain Atlas
Allen Brain Atlas is an Allen Institute collection of brain map atlases, datasets, APIs, and analysis tools covering mouse, human, and non-human primate brain resources.
Annotated Behaviour and Observability Dataset (ABODe)
ABODe is a University of Edinburgh DataShare dataset for behavior classification in group-housed mice using home-cage video, identities, bounding boxes, ground-plate positions, and annotator labels.
DANDI Archive for NWB datasets
DANDI is a BRAIN Initiative archive for publishing and sharing neurophysiology data, including electrophysiology, optophysiology, and behavioral data packaged as NWB and related standards.
International Brain Laboratory public data
The International Brain Laboratory public data releases expose standardized mouse decision-making experiments, including Neuropixels recordings, widefield calcium imaging, behavior, and session metadata accessed through the ONE API.
OpenNeuro
OpenNeuro is a free, open platform for sharing neuroimaging datasets, with public search, dataset pages, and download paths for web, S3, DataLad, and the OpenNeuro CLI.