ResearchPad - paleogenetics https://www.researchpad.co Default RSS Feed en-us © 2020 Newgen KnowledgeWorks <![CDATA[A tale of textiles: Genetic characterization of historical paper mulberry barkcloth from Oceania]]> https://www.researchpad.co/article/elastic_article_15748 Humans introduced paper mulberry (Broussonetia papyrifera) from Taiwan into the Pacific over 5000 years ago as a fiber source to make barkcloth textiles that were, and still are, important cultural artifacts throughout the Pacific. We have used B. papyrifera, a species closely associated to humans, as a proxy to understand the human settlement of the Pacific Islands. We report the first genetic analysis of paper mulberry textiles from historical and archaeological contexts (200 to 50 years before present) and compare our results with genetic data obtained from contemporary and herbarium paper mulberry samples. Following stringent ancient DNA protocols, we extracted DNA from 13 barkcloth textiles. We confirmed that the fiber source is paper mulberry in nine of the 13 textiles studied using the nuclear ITS-1 marker and by statistical estimates. We detected high genetic diversity in historical Pacific paper mulberry barkcloth with a set of ten microsatellites, showing new alleles and specific genetic patterns. These genetic signatures allow tracing connections to plants from the Asian homeland, Near and Remote Oceania, establishing links not observed previously (using the same genetic tools) in extant plants or herbaria samples. These results show that historic barkcloth textiles are cultural materials amenable to genetic analysis to reveal human history and that these artifacts may harbor evidence of greater genetic diversity in Pacific B. papyrifera in the past.

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<![CDATA[Paleogenetic study on the 17th century Korean mummy with atherosclerotic cardiovascular disease]]> https://www.researchpad.co/article/5aafccf3463d7e7f05234537

While atherosclerotic cardiovascular disease (ASCVD) is known to be common among modern people exposed to various risk factors, recent paleopathological studies have shown that it affected ancient populations much more frequently than expected. In 2010, we investigated a 17th century Korean female mummy with presumptive ASCVD signs. Although the resulting report was a rare and invaluable conjecture on the disease status of an ancient East Asian population, the diagnosis had been based only on anatomical and radiological techniques, and so could not confirm the existence of ASCVD in the mummy. In the present study, we thus performed a paleogenetic analysis to supplement the previous conventional diagnosis of ASCVD. In aDNA extracted from the same Korean mummy, we identified the risk alleles of seven different SNPs (rs5351, rs10757274, rs2383206, rs2383207, rs10757278, rs4380028 and rs1333049) that had already been revealed to be the major risk loci of ASCVD in East Asian populations. The reliability of this study could be enhanced by cross-validation using two different analyses: Sanger and SNaPshot techniques. We were able to establish that the 17th century Korean female had a strong genetic predisposition to increased risk of ASCVD. The current paleogenetic diagnosis, the first of its kind outside Europe, re-confirms its utility as an adjunct modality for confirmatory diagnosis of ancient ASCVD.

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<![CDATA[Advanced approach to analyzing calcareous protists for present and past pelagic ecology: Comprehensive analysis of 3D-morphology, stable isotopes, and genes of planktic foraminifers]]> https://www.researchpad.co/article/5c8acce4d5eed0c484990244

Marine protists play an important role in oceanic ecosystems and biogeochemical cycles. However, the difficulties in culturing pelagic protists indicate that their ecology and behavior remain poorly understood; phylogeographic studies based on single-cell genetic analyses have often shown that they are highly divergent at the biological species level, with variable geographic distributions. This indicates that their ecology could be complex. On the other hand, the biomineral (calcareous) shells of planktic foraminifers are widely used in geochemical analyses to estimate marine paleoenvironmental characteristics (i.e., temperature), because the shell chemical composition reflects ambient seawater conditions. Among the pelagic protists, planktic foraminifers are ideal study candidates to develop a combined approach of genetic, morphological, and geochemical methods, thus reflecting environmental and ecological characteristics. The present study precisely tested whether the DNA extraction process physically and chemically affects the shells of the planktic foraminifer Globigerinoides ruber. We used a nondestructive method for analyzing physical changes (micro-focus X-ray computed tomography (MXCT) scanning) to compare specimens at the pre- and post-DNA extraction stages. Our results demonstrate that DNA extraction has no significant effect on shell density and thickness. We measured stable carbon and oxygen isotopes on the shell of each individual in a negative control or one of two DNA-extracted groups and detected no significant differences in isotopic values among the three groups. Moreover, we evaluated isotopic variations at the biological species level with regard to their ecological characteristics such as depth habitat, life stages, and symbionts. Thus, our examination of the physiochemical effects on biomineral shells through DNA extraction shows that morphological and isotopic analyses of foraminifers can be combined with genetic analysis. These analytical methods are applicable to other shell-forming protists and microorganisms. In this study, we developed a powerful analytical tool for use in ecological and environmental studies of modern and past oceans.

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<![CDATA[Simultaneous detection of macroevolutionary patterns in phenotypic means and rate of change with and within phylogenetic trees including extinct species]]> https://www.researchpad.co/article/5c644869d5eed0c484c2e64a

Recognizing evolutionary trends in phenotypic means and rates requires the application of phylogenetic comparative methods (PCMs). Most PCMs are unsuited to make full use of fossil information, which is a drawback, given the inclusion of such data improves, and in some cases even corrects, the proper understanding of trait evolution. Here we present a new computer application, written in R, that allows the simultaneous computation of temporal trends in phenotypic mean and evolutionary rate along a phylogeny, and to contrast such patterns among different clades within the tree.

By using simulation experiments, we show the new implementation, names search.trend is as powerful as existing PCM tools in discerning macroevolutionary patterns in phenotypic means and rates, but differently from any other PCM allows comparing individual clades to each other, and provides rich information about trait evolution for all lineages in the tree.

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<![CDATA[Effect of barriers and distance on song, genetic, and morphological divergence in the highland endemic Timberline Wren (Thryorchilus browni, Troglodytidae)]]> https://www.researchpad.co/article/5c2544e5d5eed0c48442bad2

Populations may become isolated by distance, geographic barriers or both. Isolated populations often diverge in behavioral, morphological and genetic traits as a result of reduced inter-population gene flow. Highland species commonly present naturally fragmented distributions that confine populations to the highest mountain peaks, isolated by mountain passes and distance. The endemic Timberline Wren (Thryorchilus browni) inhabits the highlands of the Talamanca mountain range, including western Panama, and the highest peak in the Central Volcanic mountain range of Costa Rica. Using microsatellites and song recordings we studied the effect of a geographic barrier and distance on song, genetic and morphological divergence among four populations in Costa Rica. A lowland mountain pass resulted in the largest genetic, vocal, and morphological (bill length) differences among populations, likely due to reduce the gene flow. Cultural drift and assortative mating by females selecting songs from their own population likely accentuates the effect of isolation and limited gene flow between populations. This pattern of population divergence has been found in other Neotropical highland birds, but over larger geographical scales. We conclude that mountain passes and distance both reduce gene flow between populations in recently-isolated highland species with restricted distributions.

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<![CDATA[The role of Pleistocene climate change in the genetic variability, distribution and demography of Proechimys cuvieri and P. guyannensis (Rodentia: Echimyidae) in northeastern Amazonia]]> https://www.researchpad.co/article/5c215141d5eed0c4843f95f9

The spiny rats, genus Proechimys, have the highest species richness within the Echimyidae family, as well as species with high genetic variability. The genus distribution includes tropical South America and Central America south to Honduras. In this study, we evaluate the phylogeographic histories of Proechimys guyannensis and P. cuvieri using cytochrome b, in a densely sampled area in northeastern Amazon where both species are found in sympatry in different environments. For each species, Bayesian and Maximum Likelihood phylogenetic analysis were congruent and recovered similar clades in the studied area. Bayesian phylogenetic analysis using a relaxed molecular clock showed that these clusters of haplotypes diversified during Pleistocene for both species. Apparently, the large rivers of the region did not act as barriers, as some clades include specimens collected from opposite banks of Oiapoque, Araguari and Jari rivers. Bayesian skyline plot analysis showed recent demographic expansion in both species. The Pleistocene climatic changes in concert with the geologic changes in the Amazon fan probably acted as drivers in the diversification that we detected in these two spiny rats. Proechimys cuvieri and P. guyannensis show genetic structure in the eastern part of the Guiana region. Greater genetic distances observed in P. guyannensis, associated with highly structured groups, suggest that more detailed studies of systematics and ecology should be directed to this species.

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<![CDATA[Reinterpretation of an endangered taxon based on integrative taxonomy: The case of Cynara baetica (Compositae)]]> https://www.researchpad.co/article/5c0841c7d5eed0c484fcab77

The Strait of Gibraltar, the gateway between the Atlantic Ocean and the Mediterranean Sea, has a convulsive geological history, with recurring closing and opening events since the late Miocene. As a consequence, this region has played a major role in the evolutionary history of many species. Cynara baetica (Compositae) is a diploid perennial herb distributed in both sides of this strait. It is currently subdivided into two subspecies: C. baetica subsp. baetica for the Spanish populations, and C. baetica subsp. maroccana for the Moroccan ones. Following three different approximations of species delimitation, including phylogenetic and population genetic analyses (based on three AFLP primer combinations and two intergenic spacers of cpDNA), ecological niche modeling (ENM) and morphological studies, this taxon is investigated and reinterpreted. The results obtained showed a clear genetic, morphological and ecological differentiation between the two taxa and the important role played by the Strait of Gibraltar as a geographical barrier. Based on this evidence, the current taxonomic treatment is modified (both taxa should recover their specific rank) and specific conservation guidelines are proposed for the newly delimited taxa.

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<![CDATA[Quillworts from the Amazon: A multidisciplinary populational study on Isoetes serracarajensis and Isoetes cangae]]> https://www.researchpad.co/article/5b87837240307c3c45097671

Isoetes are ancient quillworts members of the only genus of the order Isoetales. The genus is slow evolving but is resilient, and widespread worldwide. Two recently described species occur in the Eastern Brazilian Amazon, Isoetes serracarajensis and Isoetes cangae. They are found in the ironstone grasslands known as Canga. While I. serracarajensis is present mostly in seasonal water bodies, I. cangae is known to occur in a single permanent lake at the South mountain range. In this work, we undertake an extensive morphological, physiological and genetic characterization of both species to establish species boundaries and better understand the morphological and genetic features of these two species. Our results indicate that the morphological differentiation of the species is subtle and requires a quantitative assessment of morphological elements of the megaspore for diagnosis. We did not detect differences in microspore output, but morphological peculiarities may establish a reproductive barrier. Additionally, genetic analysis using DNA barcodes and whole chloroplast genomes indicate that although the plants are genetically very similar both approaches provide diagnostic characters. There was no indication of population structuring I. serracarajensis. These results set the basis for a deeper understanding of the evolution of the Isoetes genus.

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<![CDATA[Early Medieval Muslim Graves in France: First Archaeological, Anthropological and Palaeogenomic Evidence]]> https://www.researchpad.co/article/5989daf5ab0ee8fa60bc2901

The rapid Arab-Islamic conquest during the early Middle Ages led to major political and cultural changes in the Mediterranean world. Although the early medieval Muslim presence in the Iberian Peninsula is now well documented, based in the evaluation of archeological and historical sources, the Muslim expansion in the area north of the Pyrenees has only been documented so far through textual sources or rare archaeological data. Our study provides the first archaeo-anthropological testimony of the Muslim establishment in South of France through the multidisciplinary analysis of three graves excavated at Nimes. First, we argue in favor of burials that followed Islamic rites and then note the presence of a community practicing Muslim traditions in Nimes. Second, the radiometric dates obtained from all three human skeletons (between the 7th and the 9th centuries AD) echo historical sources documenting an early Muslim presence in southern Gaul (i.e., the first half of 8th century AD). Finally, palaeogenomic analyses conducted on the human remains provide arguments in favor of a North African ancestry of the three individuals, at least considering the paternal lineages. Given all of these data, we propose that the skeletons from the Nimes burials belonged to Berbers integrated into the Umayyad army during the Arab expansion in North Africa. Our discovery not only discusses the first anthropological and genetic data concerning the Muslim occupation of the Visigothic territory of Septimania but also highlights the complexity of the relationship between the two communities during this period.

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<![CDATA[Outlining the Ancestry Landscape of Colombian Admixed Populations]]> https://www.researchpad.co/article/5989db1dab0ee8fa60bce850

The ancestry of the Colombian population comprises a large number of well differentiated Native communities belonging to diverse linguistic groups. In the late fifteenth century, a process of admixture was initiated with the arrival of the Europeans, and several years later, Africans also became part of the Colombian population. Therefore, the genepool of the current Colombian population results from the admixture of Native Americans, Europeans and Africans. This admixture occurred differently in each region of the country, producing a clearly stratified population. Considering the importance of population substructure in both clinical and forensic genetics, we sought to investigate and compare patterns of genetic ancestry in Colombia by studying samples from Native and non-Native populations living in its 5 continental regions: the Andes, Caribe, Amazonia, Orinoquía, and Pacific regions. For this purpose, 46 AIM-Indels were genotyped in 761 non-related individuals from current populations. Previously published genotype data from 214 Colombian Natives from five communities were used for population comparisons. Significant differences were observed between Native and non-Native populations, among non-Native populations from different regions and among Native populations from different ethnic groups. The Pacific was the region with the highest African ancestry, Amazonia harboured the highest Native ancestry and the Andean and Orinoquían regions showed the highest proportion of European ancestry. The Andean region was further sub-divided into 6 sub-regions: North East, Central West, Central East, West, South West and South East. Among these regions, the South West region showed a significantly lower European admixture than the other regions. Hardy-Weinberg equilibrium and variance values of ancestry among individuals within populations showed a potential stratification of the Pacific population.

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<![CDATA[Inability of ‘Whole Genome Amplification’ to Improve Success Rates for the Biomolecular Detection of Tuberculosis in Archaeological Samples]]> https://www.researchpad.co/article/5989db42ab0ee8fa60bd71ff

We assessed the ability of whole genome amplification (WGA) to improve the efficiency of downstream polymerase chain reactions (PCRs) directed at ancient DNA (aDNA) of members of the Mycobacterium tuberculosis complex (MTBC). Using extracts from a variety of bones and a tooth from human skeletons with or without lesions indicative of tuberculosis, from multiple time periods, we obtained inconsistent results. We conclude that WGA does not provide any advantage in studies of MTBC aDNA. The sporadic nature of our results are probably due to the fact that WGA is itself a PCR-based procedure which, although designed to deal with fragmented DNA, might be inefficient with the low concentration of templates in an aDNA extract. As such, WGA is subject to similar, if not the same, restrictions as PCR when applied to aDNA.

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<![CDATA[Ancient Mitochondrial Capture as Factor Promoting Mitonuclear Discordance in Freshwater Fishes: A Case Study in the Genus Squalius (Actinopterygii, Cyprinidae) in Greece]]> https://www.researchpad.co/article/5989da1cab0ee8fa60b7d0f9

Hybridization and incomplete lineage sorting are common confounding factors in phylogeny and speciation resulting in mitonuclear disparity. Mitochondrial introgression, a particular case of hybridization, may, in extreme cases, lead to replacement of the mitochondrial genome of one species with that of another (mitochondrial capture). We investigated mitochondrial introgression involving two species of the cyprinid genus Squalius in the western Peloponnese region of Greece using molecular and morphological data. We found evidence of complete mitochondrial introgression of Squalius keadicus into two populations recognized as Squalius peloponensis from the Miras and Pamissos River basins and a divergence of mitochondrial genomes of S. keadicus from the Evrotas basin from that of the introgressed populations dating from the Pleistocene. Secondary contact among basins is a possible factor in connection of the species and the introgression event. Morphological analyses support the hypothesis of mitochondrial introgression, as S. keadicus was different from the other three populations recognized as S. peloponensis, although significant differences were found among the four populations. Isolation by geographical barriers arose during Pleistocene in the western Peloponnese were the source of the evolution of the two reciprocally monophyletic subclades found in the S. keadicus mitochondrial clade, and the morphological differences found among the four populations. Along with the lack of structure in the nuclear genome in the three populations ascribed to S. peloponensis, this suggests an incipient speciation process occurring in these Squalius species in the western Peloponnese.

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<![CDATA[Molecular Phylogeny of Gueldenstaedtia and Tibetia (Fabaceae) and Their Biogeographic Differentiation within Eastern Asia]]> https://www.researchpad.co/article/5989da99ab0ee8fa60ba3164

Tibetia and Gueldenstaedtia are two morphologically similar and small genera in Fabaceae, with distributions largely corresponding to the Sino-Himalayan and Sino-Japanese subkingdoms in eastern Asia, respectively. These two genera have confusing relationships based on morphology; therefore, we aimed to provide a clear understanding of their phylogenetic and biogeographic evolution within eastern Asia. In our investigations we included 88 samples representing five Gueldenstaedtia species, five Tibetia species, and outgroup species were sequenced using five markers (nuclear: ITS; chloroplast: matK, trnL-F, psbA-trnH and rbcL). Our phylogenetic results support (1) the monophyly of Tibetia and of Gueldenstaedtia, respectively; and (2) that Tibetia and Gueldenstaedtia are sister genera. Additionally, our data identified that Tibetia species had much higher sequence variation than Gueldenstaedtia species. Our results suggest that the two genera were separated from each other about 17.23 million years ago, which is congruent with the Himalayan orogeny and the uplift of the Tibetan Plateau in the mid Miocene. The divergence of Tibetia and Gueldenstaedtia is strongly supported by the separation of the Sino-Himalayan and Sino-Japanese region within eastern Asia. In addition, the habitat heterogeneity may accelerate the molecular divergence of Tibetia in the Sino-Himalayan region.

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<![CDATA[Post Mortem DNA Degradation of Human Tissue Experimentally Mummified in Salt]]> https://www.researchpad.co/article/5989da8eab0ee8fa60b9ee4b

Mummified human tissues are of great interest in forensics and biomolecular archaeology. The aim of this study was to analyse post mortem DNA alterations in soft tissues in order to improve our knowledge of the patterns of DNA degradation that occur during salt mummification. In this study, the lower limb of a female human donor was amputated within 24 h post mortem and mummified using a process designed to simulate the salt dehydration phase of natural or artificial mummification. Skin and skeletal muscle were sampled at multiple time points over a period of 322 days and subjected to genetic analysis. Patterns of genomic fragmentation, miscoding lesions, and overall DNA degradation in both nuclear and mitochondrial DNA was assessed by different methods: gel electrophoresis, multiplex comparative autosomal STR length amplification, cloning and sequence analysis, and PCR amplification of different fragment sizes using a damage sensitive recombinant polymerase. The study outcome reveals a very good level of DNA preservation in salt mummified tissues over the course of the experiment, with an overall slower rate of DNA fragmentation in skin compared to muscle.

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<![CDATA[Revealing phenotype-associated functional differences by genome-wide scan of ancient haplotype blocks]]> https://www.researchpad.co/article/5989db59ab0ee8fa60bdf11d

Genome-wide scans for positive selection have become important for genomic medicine, and many studies aim to find genomic regions affected by positive selection that are associated with risk allele variations among populations. Most such studies are designed to detect recent positive selection. However, we hypothesize that ancient positive selection is also important for adaptation to pathogens, and has affected current immune-mediated common diseases. Based on this hypothesis, we developed a novel linkage disequilibrium-based pipeline, which aims to detect regions associated with ancient positive selection across populations from single nucleotide polymorphism (SNP) data. By applying this pipeline to the genotypes in the International HapMap project database, we show that genes in the detected regions are enriched in pathways related to the immune system and infectious diseases. The detected regions also contain SNPs reported to be associated with cancers and metabolic diseases, obesity-related traits, type 2 diabetes, and allergic sensitization. These SNPs were further mapped to biological pathways to determine the associations between phenotypes and molecular functions. Assessments of candidate regions to identify functions associated with variations in incidence rates of these diseases are needed in the future.

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<![CDATA[Three Thousand Years of Continuity in the Maternal Lineages of Ancient Sheep (Ovis aries) in Estonia]]> https://www.researchpad.co/article/5989dadfab0ee8fa60bbb196

Although sheep (Ovis aries) have been one of the most exploited domestic animals in Estonia since the Late Bronze Age, relatively little is known about their genetic history. Here, we explore temporal changes in Estonian sheep populations and their mitochondrial genetic diversity over the last 3000 years. We target a 558 base pair fragment of the mitochondrial hypervariable region in 115 ancient sheep from 71 sites in Estonia (c. 1200 BC–AD 1900s), 19 ancient samples from Latvia, Russia, Poland and Greece (6800 BC–AD 1700), as well as 44 samples of modern Kihnu native sheep breed. Our analyses revealed: (1) 49 mitochondrial haplotypes, associated with sheep haplogroups A and B; (2) high haplotype diversity in Estonian ancient sheep; (3) continuity in mtDNA haplotypes through time; (4) possible population expansion during the first centuries of the Middle Ages (associated with the establishment of the new power regime related to 13th century crusades); (5) significant difference in genetic diversity between ancient populations and modern native sheep, in agreement with the beginning of large-scale breeding in the 19th century and population decline in local sheep. Overall, our results suggest that in spite of the observed fluctuations in ancient sheep populations, and changes in the natural and historical conditions, the utilisation of local sheep has been constant in the territory of Estonia, displaying matrilineal continuity from the Middle Bronze Age through the Modern Period, and into modern native sheep.

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<![CDATA[Ancient DNA Analysis Suggests Negligible Impact of the Wari Empire Expansion in Peru’s Central Coast during the Middle Horizon]]> https://www.researchpad.co/article/5989da43ab0ee8fa60b8abca

The analysis of ancient human DNA from South America allows the exploration of pre-Columbian population history through time and to directly test hypotheses about cultural and demographic evolution. The Middle Horizon (650–1100 AD) represents a major transitional period in the Central Andes, which is associated with the development and expansion of ancient Andean empires such as Wari and Tiwanaku. These empires facilitated a series of interregional interactions and socio-political changes, which likely played an important role in shaping the region’s demographic and cultural profiles. We analyzed individuals from three successive pre-Columbian cultures present at the Huaca Pucllana archaeological site in Lima, Peru: Lima (Early Intermediate Period, 500–700 AD), Wari (Middle Horizon, 800–1000 AD) and Ychsma (Late Intermediate Period, 1000–1450 AD). We sequenced 34 complete mitochondrial genomes to investigate the potential genetic impact of the Wari Empire in the Central Coast of Peru. The results indicate that genetic diversity shifted only slightly through time, ruling out a complete population discontinuity or replacement driven by the Wari imperialist hegemony, at least in the region around present-day Lima. However, we caution that the very subtle genetic contribution of Wari imperialism at the particular Huaca Pucllana archaeological site might not be representative for the entire Wari territory in the Peruvian Central Coast.

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<![CDATA[Spatial Genetic Structure of the Abundant and Widespread Peatmoss Sphagnum magellanicum Brid.]]> https://www.researchpad.co/article/5989da63ab0ee8fa60b916eb

Spore-producing organisms have small dispersal units enabling them to become widespread across continents. However, barriers to gene flow and cryptic speciation may exist. The common, haploid peatmoss Sphagnum magellanicum occurs in both the Northern and Southern hemisphere, and is commonly used as a model in studies of peatland ecology and peatmoss physiology. Even though it will likely act as a rich source in functional genomics studies in years to come, surprisingly little is known about levels of genetic variability and structuring in this species. Here, we assess for the first time how genetic variation in S. magellanicum is spatially structured across its full distribution range (Northern Hemisphere and South America). The morphologically similar species S. alaskense was included for comparison. In total, 195 plants were genotyped at 15 microsatellite loci. Sequences from two plastid loci (trnG and trnL) were obtained from 30 samples. Our results show that S. alaskense and almost all plants of S. magellanicum in the northern Pacific area are diploids and share the same gene pool. Haploid plants occur in South America, Europe, eastern North America, western North America, and southern Asia, and five genetically differentiated groups with different distribution ranges were found. Our results indicate that S. magellanicum consists of several distinct genetic groups, seemingly with little or no gene flow among them. Noteworthy, the geographical separation of diploids and haploids is strikingly similar to patterns found within other haploid Sphagnum species spanning the Northern Hemisphere. Our results confirm a genetic division between the Beringian and the Atlantic that seems to be a general pattern in Sphagnum taxa. The pattern of strong genetic population structuring throughout the distribution range of morphologically similar plants need to be considered in future functional genomic studies of S. magellanicum.

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<![CDATA[Neandertal-like traits visible in the internal structure of non-supranuchal fossae of some recent Homo sapiens: The problem of their identification in hominins and phylogenetic implications]]> https://www.researchpad.co/article/5c915f5ad5eed0c48420a67f

Although recently the internal structure of the non-supranuchal fossa of Homo sapiens has been described and compared to that observed in the Neandertal suprainiac fossa, until now it has not been examined in any modern human children. In this study, the internal structure of this fossa in the occipital bones of three children (two aged 3‒4 years and one aged 5 years ± 16 months) and one adult individual representing recent Homo sapiens from Australia was analysed and compared to that of the Neandertal suprainiac fossa. In order to analyse the internal composition of the fossae of the examined specimens, initially, high-resolution micro-CT datasets were obtained for their occipital bones; next, 3D topographic maps of the variation in thickness of structural layers of the occipital bones were made and 2D virtual sections in the median region of these fossae were prepared. In the fossa of one immature individual, the thinning of the diploic layer characteristic of a Neandertal suprainiac fossa was firmly diagnosed. The other Neandertal-like trait, concerning the lack of substantial thinning of the external table of the bone in the region of the fossa, was established in two individuals (one child and one adult) due to the observation of an irregular pattern of the thickness of this table in the other specimens, suggesting the presence of an inflammatory process. Our study presents, for the first time, Neandertal-like traits (but not the whole set of features that justifies the autapomorphic status of the Neandertal supraniac fossa) in the internal structure of non-supranuchal fossae of some recent Homo sapiens. We discuss the phylogenetic implications of the results of our analysis and stress the reasons that use of the 3D topographic mapping method is important for the correct diagnosis of Neandertal traits of the internal structure of occipital fossae.

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<![CDATA[Natural Constraints to Species Diversification]]> https://www.researchpad.co/article/5989dacaab0ee8fa60bb3d55

Identifying modes of species diversification is fundamental to our understanding of how biodiversity changes over evolutionary time. Diversification modes are captured in species phylogenies, but characterizing the landscape of diversification has been limited by the analytical tools available for directly comparing phylogenetic trees of groups of organisms. Here, we use a novel, non-parametric approach and 214 family-level phylogenies of vertebrates representing over 500 million years of evolution to identify major diversification modes, to characterize phylogenetic space, and to evaluate the bounds and central tendencies of species diversification. We identify five principal patterns of diversification to which all vertebrate families hold. These patterns, mapped onto multidimensional space, constitute a phylogenetic space with distinct properties. Firstly, phylogenetic space occupies only a portion of all possible tree space, showing family-level phylogenies to be constrained to a limited range of diversification patterns. Secondly, the geometry of phylogenetic space is delimited by quantifiable trade-offs in tree size and the heterogeneity and stem-to-tip distribution of branching events. These trade-offs are indicative of the instability of certain diversification patterns and effectively bound speciation rates (for successful clades) within upper and lower limits. Finally, both the constrained range and geometry of phylogenetic space are established by the differential effects of macroevolutionary processes on patterns of diversification. Given these properties, we show that the average path through phylogenetic space over evolutionary time traverses several diversification stages, each of which is defined by a different principal pattern of diversification and directed by a different macroevolutionary process. The identification of universal patterns and natural constraints to diversification provides a foundation for understanding the deep-time evolution of biodiversity.

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