More Like this

1. Phylogenetic and environmental effects on limb bone structure in gorillas

   https://doi.org/10.1002/ajpa.23437  

   Ruff, Christopher B. ; Burgess, M. Loring ; Junno, Juho‐Antti ; Mudakikwa, Antoine ; Zollikofer, Christophe P. E. ; Ponce de León, Marcia S. ; McFarlin, Shannon C. ( February 2018 , American Journal of Physical Anthropology)

   The effects of phylogeny and locomotor behavior on long bone structural proportions are assessed through comparisons between adult and ontogenetic samples of extant gorillas.

   A total of 281 wild‐collected individuals were included in the study, divided into four groups that vary taxonomically and ecologically: western lowland gorillas (G. g. gorilla), lowland and highland grauer gorillas(G. b. graueri), and Virunga mountain gorillas (G. b. beringei). Lengths and articular breadths of the major long bones (except the fibula) were measured, and diaphyseal cross‐sectional geometric properties determined using computed tomography. Ages of immature specimens (n = 145) were known or estimated from dental development. Differences between groups in hind limb to forelimb proportions were assessed in both adults and during development.

   Diaphyseal strength proportions among adults vary in parallel with behavioral/ecological differences, and not phylogeny. The more arboreal western lowland and lowland grauer gorillas have relatively stronger forelimbs than the more terrestrial Virunga mountain gorillas, while the behaviorally intermediate highland grauer gorillas have intermediate proportions. Diaphyseal strength proportions are similar in young infants but diverge after 2 years of age in western lowland and mountain gorillas, at the same time that changes in locomotor behavior occur. There are no differences between groups in length or articular proportions among either adults or immature individuals.

   Long bone diaphyseal strength proportions in gorillas are developmentally plastic, reflecting behavior, while length and articular proportions are much more genetically canalized. These findings have implications for interpreting morphological variation among fossil taxa.

    

   more » « less
2. Gut microbiome composition of wild western lowland gorillas is associated with individual age and sex factors

   https://doi.org/10.1002/ajpa.23842  

   Pafčo, Barbora ; Sharma, Ashok K. ; Petrželková, Klára J. ; Vlčková, Klára ; Todd, Angelique ; Yeoman, Carl J. ; Wilson, Brenda A. ; Stumpf, Rebecca ; White, Bryan A. ; Nelson, Karen E. ; et al ( April 2019 , American Journal of Physical Anthropology)

   Environmental and ecological factors, such as geographic range, anthropogenic pressure, group identity, and feeding behavior are known to influence the gastrointestinal microbiomes of great apes. However, the influence of individual host traits such as age and sex, given specific dietary and social constraints, has been less studied. The objective of this investigation was to determine the associations between an individual's age and sex on the diversity and composition of the gut microbiome in wild western lowland gorillas.

   Publicly available 16S rRNA data generated from fecal samples of different groups ofGorilla gorillagorillain the Central African Republic were downloaded and bioinformatically processed. The groups analyzed included habituated, partially habituated and unhabituated gorillas, sampled during low fruit (dry,n = 28) and high fruit (wet,n = 82) seasons. Microbial community analyses (alpha and beta diversity and analyses of discriminant taxa), in tandem with network‐wide approaches, were used to (a) mine for specific age and sex based differences in gut bacterial community composition and to (b) asses for gut community modularity and bacterial taxa with potential functional roles, in the context of seasonal food variation, and social group affiliation.

   Both age and sex significantly influenced gut microbiome diversity and composition in wild western lowland gorillas. However, the largest differences were observed between infants and adults in habituated groups and between adults and immature gorillas within all groups, and across dry and wet seasons. Specifically, although adults always showed greater bacterial richness than infants and immature gorillas, network‐wide analyses showed higher microbial community complexity and modularity in the infant gorilla gut. Sex‐based microbiome differences were not evident among adults, being only detected among immature gorillas.

   The results presented point to a dynamic gut microbiome inGorillaspp., associated with ontogeny and individual development. Of note, the gut microbiomes of breastfeeding infants seemed to reflect early exposure to complex, herbaceous vegetation. Whether increased compositional complexity of the infant gorilla gut microbiome is an adaptive response to an energy‐limited diet and an underdeveloped gut needs to be further tested. Overall, age and sex based gut microbiome differences, as shown here, maybe mainly attributed to access to specific feeding sources, and social interactions between individuals within groups.

    

   more » « less
3. Allometry and advancing age significantly structure craniofacial variation in adult female baboons

   https://doi.org/10.1111/joa.13005  

   Joganic, Jessica L. ; Heuzé, Yann ( May 2019 , Journal of Anatomy)

   Primate craniofacial growth is traditionally assumed to cease upon maturation or at least be negligible, whereas bony remodeling is typically associated with advanced adult age and, in particular, tooth loss. Therefore, size and shape of the craniofacial skeleton of young and middle‐aged adults should be stable. However, research on both modern and historic human samples suggests that portions of theCFSexhibit age‐related changes in mature individuals, both related to and independent of tooth loss. These results demonstrate that the age‐category ‘adult’ is heterogeneous, containing individuals demonstrating post‐maturational age‐related variation, but the topic remains understudied outside of humans and in the cranial vault and base. Our research quantifies variation in a sample of captive adult female baboons (n = 97) in an effort to understand how advancing age alters the matureCFS. Craniometric landmarks and sliding semilandmarks were collected fromcomputed tomography (CT)scans of adult baboons aged 7–32 years old. To determine whether craniofacial morphology is sensitive to aging mechanisms and whether any such effects are differentially distributed throughout the cranium, geometric morphometric techniques were employed to compare the shapes of various cranial regions among individuals of increasing age. Unexpectedly, the biggest form differences were observed between young and middle‐aged adults, rather than between adults with full dentitions and those with some degree of tooth loss. Shape variation was greatest in masticatory and nuchal musculature attachment areas. Our results indicate that thecraniofacial skeletonchanges form during adulthood in baboons, raising interesting questions about the molecular and biological mechanisms governing these changes.

    

   more » « less
4. Interspecific Variation of Calcaneal Morphology in Gorillas

   Harper, Christine M. ; Ruff, Christopher B. ; Sylvester, Adam D. ( February 2019 , American journal of physical anthropology)

   The foot plays a prominent role in weight-bearing suggesting it may reflect locomotor variation. Despite the immense amount of foot research, the calcaneus has been relatively understudied. Here we analyzed the entire calcaneal shape of Gorilla gorilla gorilla (n=41), Gorilla beringei graueri (n=17) and Gorilla beringei beringei (n=8) to understand how morphology relates to locomotor behavior. Calcanei were surface scanned and external shape analyzed using a three-dimensional geometric morphometric sliding semilandmark analysis. Semilandmarks were slid to minimize the bending energy of the thin plate spline interpolation function relative to the updated Procrustes average. Generalized Procrustes Analysis was used to align landmark configurations and shape variation was summarized using a principal components analysis. Procrustes distances between species were calculated and resampling statistics were run to test for group differences. All subspecies demonstrate statistically different morphologies (p<0.005 for pairwise comparisons). G. b. graueri separates from other subspecies based on posterolateral morphology, with G. b. graueri demonstrating an elongated peroneal trochlea, and thus more bone superiorly than G. g. gorilla. Compared to G. b. beringei, G. b. graueri has less bone inferiorly near the tuberosity. Cuboid and posterior talar facet shapes correlate with arboreality. G. b. beringei (most terrestrial) has a flatter cuboid facet and a more transversely oriented/relatively smaller posterior talar facet than G. g. gorilla (most arboreal) and G. b. graueri represents an intermediate morphology. These differences demonstrate a relationship between calcaneal shape and locomotor behavior and suggest that G. b. graueri may load its foot differently from the other subspecies. This project was supported by NSF grant # BCS - 1824630. 

   more » « less
5. Patterns of postnatal ontogeny of the skull and lower jaw of snakes as revealed by micro‐ CT scan data and three‐dimensional geometric morphometrics

   https://doi.org/10.1111/joa.12509  

   Palci, Alessandro ; Lee, Michael S. Y. ; Hutchinson, Mark N. ( June 2016 , Journal of Anatomy)

   We compared the head skeleton (skull and lower jaw) of juvenile and adult specimens of five snake species [Anilios(=Ramphotyphlops)bicolor,Cylindrophis ruffus,Aspidites melanocephalus,Acrochordus arafurae, andNotechis scutatus] and two lizard outgroups (Ctenophorus decresii,Varanus gilleni). All major ontogenetic changes observed were documented both qualitatively and quantitatively. Qualitative comparisons were based on high‐resolution micro‐CTscanning of the specimens, and detailed quantitative analyses were performed using three‐dimensional geometric morphometrics. Two sets of landmarks were used, one for accurate representation of the intraspecific transformations of each skull and jaw configuration, and the other for comparison between taxa. Our results document the ontogenetic elaboration of crests and processes for muscle attachment (especially for cervical and adductor muscles); negative allometry in the braincase of all taxa; approximately isometric growth of the snout of all taxa exceptVaranusandAnilios(positively allometric); and positive allometry in the quadrates of the macrostomatan snakesAspidites,AcrochordusandNotechis, but also, surprisingly, in the iguanian lizardCtenophorus. Ontogenetic trajectories from principal component analysis provide evidence for paedomorphosis inAniliosand peramorphosis inAcrochordus. Some primitive (lizard‐like) features are described for the first time in the juvenileCylindrophis. Two distinct developmental trajectories for the achievement of the macrostomatan (large‐gaped) condition in adult snakes are documented, driven either by positive allometry of supratemporal and quadrate (in pythons), or of quadrate alone (in sampled caenophidians); this is consistent with hypothesised homoplasy in this adaptive complex. Certain traits (e.g. shape of coronoid process, marginal tooth counts) are more stable throughout postnatal ontogeny than others (e.g. basisphenoid keel), with implications for their reliability as phylogenetic characters.

    

   more » « less