To perform a systematic review and meta-analysis to determine whether fluid and imaging astrocyte biomarkers are altered in Alzheimer disease (AD).
PubMed and Web of Science databases were searched ...for articles reporting fluid or imaging astrocyte biomarkers in AD. Pooled effect sizes were determined with standardized mean differences (SMDs) using the Hedge G method with random effects to determine biomarker performance. Adapted questions from the Quality Assessment of Diagnostic Accuracy Studies were applied for quality assessment. A protocol for this study has been previously registered in PROSPERO (registration number: CRD42020192304).
The initial search identified 1,425 articles. After exclusion criteria were applied, 33 articles (a total of 3,204 individuals) measuring levels of glial fibrillary acidic protein (GFAP), S100B, chitinase-3-like protein 1 (YKL-40), and aquaporin 4 in the blood and CSF, as well as monoamine oxidase-B indexed by PET
C-deuterium-l-deprenyl, were included. GFAP (SMD 0.94, 95% confidence interval CI 0.71-1.18) and YKL-40 (SMD 0.76, 95% CI 0.63-0.89) levels in the CSF and S100B levels in the blood (SMD 2.91, 95% CI 1.01-4.8) were found to be significantly increased in patients with AD.
Despite significant progress, applications of astrocyte biomarkers in AD remain in their early days. This meta-analysis demonstrated that astrocyte biomarkers are consistently altered in AD and supports further investigation for their inclusion in the AD clinical research framework for observational and interventional studies.
Geographic gradients in the species richness of non‐human primates have traditionally been attributed to the variation in forest productivity (related to precipitation levels), although an ...all‐inclusive, global‐scale analysis has never been conducted. We perform a more comprehensive test on the role of precipitation and biomass production and propose an alternative hypothesis – the variation in vertical structure of forest habitats as measured by forest canopy height – in determining primate species richness on a global scale. Considering the potential causal relationships among precipitation, productivity and forest structure, we arranged these variables within a path framework to assess their direct and indirect associations with the pattern of primate species richness using structural equation modelling. The analysis also accounted for the influence of spatial autocorrelation in the relationships and assessed possible historical differences among biogeographical regions. The path coefficients indicate that forest canopy height (used as a proxy for vertical forest structure) is a better predictor of primate species richness than either precipitation or productivity on both global and continental scales. The only exception was Asia, where precipitation prevailed, albeit independently from productivity or forest structure. The influence of spatially structured processes varied markedly among biogeographical regions. Our results challenge the traditional rainfall‐based viewpoint in favour of forest distribution and structure as primary drivers of primate species richness, which aggregate potential effects from both climatic factors and habitat complexity. These findings may support predictions of the impact of forest removal on primate species richness.
Primate population density often varies considerably between sites, reflecting differences in site conditions and resource availability. Understanding these differences may provide important insights ...for habitat management. We identified environmental variables that affect the population density of
Callicebus coimbrai
in forest patches throughout its geographic distribution in northeastern Brazil. We sampled the vegetation structure of 19 forest patches and assessed the composition of the surrounding landscape and the resistance of the surrounding matrix to the movement of
C. coimbrai
. We used the number of responses of
C. coimbrai
to playback to estimate the species density in each patch. The density of
C. coimbrai
was positively related to understory vegetation density, and tree diameter and density, but not to the surrounding landscape composition. The sites with the highest densities were concentrated in the center of the species geographic range and only one of the forest patches may be large enough to host a viable population of
C. coimbrai
over the long term. Denser understories and larger and closed-spaced trees were related to food availability, and possibly also to predator avoidance, although most predators were extirpated from the region.
C. coimbrai
tolerate and may even benefit from forest disturbance, depending on how the process has changed the vegetation structure. Our results emphasize the need to enhance the connectivity of the forest patches, particularly in the central portion of the species distribution. Our findings suggest that a whole-range approach is effective to identify the drivers of species density, and priority areas and conservation strategies.
Land use changes have profound effects on populations of Neotropical primates, and ongoing climate change is expected to aggravate this scenario. The titi monkeys from eastern Brazil (Callicebus ...personatus group) have been particularly affected by this process, with four of the five species now allocated to threatened conservation status categories. Here, we estimate the changes in the distribution of these titi monkeys caused by changes in both climate and land use. We also use demographic‐based, functional landscape metrics to assess the magnitude of the change in landscape conditions for the distribution predicted for each species. We built species distribution models (SDMs) based on maximum entropy for current and future conditions (2070), allowing for different global circulation models and contrasting scenarios of glasshouse gas concentrations. We refined the SDMs using a high‐resolution map of habitat remnants. We then calculated habitat availability and connectivity based on home‐range size and the dispersal limitations of the individual, in the context of a predicted loss of 10% of forest cover in the future. The landscape configuration is predicted to be degraded for all species, regardless of the climatic settings. This include reductions in the total cover of forest remnants, patch size and functional connectivity. As the landscape configuration should deteriorate severely in the future for all species, the prevention of further loss of populations will only be achieved through habitat restoration and reconnection to counteract the negative effects for these and several other co‐occurring species.
ABSTRACT
Given the position of humans in the tree of life, comparative research on non‐human primates has attracted the interest of researchers in biology, medical sciences, anthropology, psychology, ...and sociology. Covariation of species' phenotypes has been of particular interest.
Learning from the historical development of comparative research with primates should thus be particularly valuable for evolutionary ecology and to improve understanding of phenotypic integration and diversity. Such learning would also help identify knowledge gaps, disputed questions, and new avenues of both basic and applied research in relation to the evolution of primate features and the conservation of our close relatives.
We conducted a historical assessment through a non‐systematic review and a systematic review, focusing on how the integration of different research lines in evolutionary ecology focused on primate phenotypic covariation unfolded throughout the 20th Century. The non‐systematic review allowed us to reconstruct the history of the discipline from its earliest origins, when bibliometric assessments were more limited in scope, and to identify the most appropriate keywords for the systematic review. We employed a standard protocol for the systematic review, applying two complementary analyses: co‐occurrence of keywords and bibliographic coupling of references. These analyses described the development of the conceptual and intellectual structures of comparative primatology from 1966 to 2020.
By identifying the most influential researchers and concept interrelations, we highlight primate phenotypes critical for the development of the discipline (in particular, brain and body sizes and behavioural patterns), showcasing the reach of these investigations for evolutionary ecology. Overall, our findings emphasise the crucial role that comparative primatology has played in developing the study of phenotypic integration and the very onset of phylogenetic comparative methods.
Cloud of keywords drawn from the literature on comparative studies on primates, including their morphological, physiological, ecological, and behavioural features, as well as methodological aspects of these studies. The word size is proportional to their appearance in these studies.
Capuchin monkeys are currently represented by four species of Cebus and eight of Sapajus. This group is taxonomically complex and several questions still need to be clarified. In the current study, ...using mtDNA markers and a larger sample representation than in previous studies, we seek to understand the phylogenetic relationships among the capuchin lineages and their historical biogeography. All 12 species of capuchins were analyzed for the mitochondrial Control Region and Cytochrome b to test two biogeographical hypotheses: "Reinvasion of the Amazon (ROA)" and "Sympatric Evolution (SEV)". The phylogenetic relationships among distinct lineages within genera is consistent with an evolutionary diversification pattern probably resulting from an explosive process of diversification and dispersal between 2.0 Ma and 3.0 Ma. Also, the analyses show that the ancestral capuchins were distributed in a wide area encompassing the Amazon and Atlantic Forest. Our results support the SEV hypothesis, showing that the current syntopic distribution of Cebus and Sapajus can be explained by a sympatric speciation event in the Amazon. We also indicate that the recently proposed species taxonomy of Cebus is not supported, and that S. cay and S. macrocephalus are a junior synonym of S. apella.
Ongoing environmental changes may reduce the population size and geographic distribution of many ecologically sensitive species. Predicting where populations will (or will not) be likely to resist ...these changes is crucial for planning their protection. The blond titi monkey (
Callicebus barbarabrownae
) is listed as Critically Endangered by the International Union for Conservation of Nature because of its small and declining population due to deforestation and hunting. The species is endemic to the Brazilian Caatinga dry forest, which has undergone extensive deforestation and climate-induced desertification. We address the extinction risk of this species in a spatially explicit context by predicting the geographic distribution of suitable areas that may permit the persistence of potentially viable populations over the next 50 years. We combined species distribution modeling with population viability analysis under more optimistic and pessimistic climate change scenarios and simulated forest loss, assessing how different populations will likely cope with these changes during the coming decades. Future models did not differ between the scenarios, but changes in the climatic suitability of the species’ habitat predicted a reduction of one-third of the currently suitable area. Viable populations in large forest remnants represent only a quarter of all known populations, and they also face a decline in climatic suitability. Smaller populations may be extirpated, regardless of the level of forest recovery. This species’ long-term persistence entails improving habitat quality and the connectivity of the large remnants to neighbor areas. Finally, the integration of spatial and temporal models is feasible and helpful to address threats and aid the conservation of primates.
Identifying the factors that determine local extinction of populations is crucial to ensure species conservation. Forest-dwelling primates are especially vulnerable to habitat fragmentation, although ...few studies have provided systematic evidence of local extinctions. Over an 11-year period, approximately 100 remnant populations of the endangered Coimbra Filho’s titi monkey (
Callicebus coimbrai
) have been found within the geographic range of the species in Bahia and Sergipe, Northeast Brazil. During the present study, extinction of 13 of these populations was recorded through intensive surveys. These extinctions were detected from evidence of intensive logging and clear-cutting, interviews with local residents and systematic searches of the sites where occurrence of the species had been confirmed in previous surveys. These local extinctions represent approximately 10 % of the known populations of
C. coimbrai
and up to 28.3 % of the area occupied by the species. Comparison of the vegetation structure in fragments where extinction was recorded and where the species still occurs indicated that sparser understorey may be a correlate of extinction, combined with the fact that extinctions occurred within fragments characterised by relatively high levels of anthropogenic disturbance. These findings reinforce the Endangered status of the species and the urgent need for intensification of conservation measures within the most impacted areas of the geographic distribution of
C. coimbrai
.
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