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Abstract Although trionychians have a rich fossil record, much of their fossil diversity is known from the Cretaceous and Paleogene, and little is known about their evolutionary history in the Neogene. We here describe cranial and shell material of trionychians from the Early Miocene Moghra Formation of Egypt that we attribute to a new carettochelyid taxon,Allaeochelys meylanisp. nov., and to theTrionyxlineage.Allaeochelys meylanisp. nov. fills a temporal gap between previously described taxa and exhibits a series of unique features, including greatly thickened cranial bones, a broad bony wall posterior to the orbit, a large fossa formed by the maxilla and premaxilla at the anterior third of the triturating surface, and a medial process on peripheral II.Allaeochelys meylanisp. nov. also documents the oldest occurrence ofCarettochelyidaeon the Afro-Arabian continent, while theTrionyxmaterial reported herein provides unambiguous evidence for the presence of this lineage on the Afro-Arabian continent no later than the Early Miocene. 

Abstract Skulls are a critical part of the crocodile through which we can distinguish between the different genera and species. Most of the crocodiles which previously studied from the Eocene–Oligocene to the Miocene times in Egypt were concerned with the identification of the genus and sometimes on the species without a detailed focusing on the evolution, comparing between them and trying to determine the ancestor or the closest species of them to the living crocodile in Egypt. The only known living species ofCrocodylusin Egypt isCrocodylus niloticuswhich inhabits Lake Nasser in Aswan, southern of Egypt. From the Cenozoic era, broad snouted crocodiles diversity had been reported in Egypt. About 35 million years ago, through the Eocene epoch, the crocodilian fossils from Fayum provided evidence of the diversity of crocodile species includingCrocodylus articepsandCrocodylus megarhinus. In addition to that, throughout the Early Miocene epoch, from about 18 million years ago, in Wadi Moghra Egypt crocodilian fossils demonstrate another diversity, extended to the first appearance ofRimasuchus lloydiwhich placed inside theOsteolaeminaelater. By various measurements and carefully morphological examination of the different species recorded from Egypt, it was found that there are high levels of variation in morphology of the skulls including their dimensions, and the sutures shapes especially between premaxilla and maxilla ventrally and also between maxilla and palatine, as well as the extension of the maxillary ramus of the ectopterygoid. Using cluster analysis, it is proven that EoceneCrocodylusis the ancestor to all known broad snouted species recorded from Egypt since the Eocene time. The closest species to the Eocene specimen is the livingCrocodylusniloticus. That in fact make that most of the broad snouted crocodiles in Egypt are endemic. 

Abstract Gaining a better understanding of the rates and patterns of meiotic recombination is crucial for improving evolutionary genomic modeling, with applications ranging from demographic to selective inference. Although previous research has provided important insights into the landscape of crossovers in humans and other haplorrhines, our understanding of both the considerably more common outcome of recombination (i.e. noncrossovers) as well as the landscapes in more distantly related primates (i.e. strepsirrhines) remains limited owing to difficulties associated with both the identification of noncrossover tracts as well as species sampling. Thus, in order to elucidate recombination patterns in this understudied branch of the primate clade, we here characterize crossover and noncrossover landscapes in aye-ayes utilizing whole-genome sequencing data from six three-generation pedigrees and three two-generation multi-sibling families, and in so doing provide novel insights into this important evolutionary process shaping genomic diversity in one of the world's most critically endangered primate species. 

Abstract The aye-aye (Daubentonia madagascariensis) is one of the 25 most endangered primate species in the world, maintaining amongst the lowest genetic diversity of any primate measured to date. Characterizing patterns of genetic variation within aye-aye populations, and the relative influences of neutral and selective processes in shaping that variation, is thus important for future conservation efforts. In this study, we performed the first whole-genome scans for positive and balancing selection in the species, utilizing high-coverage population genomic data from newly sequenced individuals. We generated null thresholds for our genomic scans by creating an evolutionarily appropriate baseline model that incorporates the demographic history of this aye-aye population, and identified a small number of candidate genes. Most notably, a suite of genes involved in olfaction—a key trait in these nocturnal primates—were identified as experiencing long-term balancing selection. We also conducted analyses to quantify the expected statistical power to detect positive and balancing selection in this population using site frequency spectrum–based inference methods, once accounting for the potentially confounding contributions of population history, mutation and recombination rate variation, as well as purifying and background selection. This work, presenting the first high-quality, genome-wide polymorphism data across the functional regions of the aye-aye genome, thus provides important insights into the landscape of episodic selective forces in this highly endangered species. 

Abstract Access to high‐quality outreach programs is crucial for preparing students for STEM careers, yet traditional classrooms often lack diverse, hands‐on learning opportunities, particularly in anatomy and evolutionary biology. We present Are You Stronger Than a Lemur?—an interactive STEM activity that introduces K‐12 students to fundamental concepts in anatomy, evolution, physics, and data analysis through real‐world applications. Participants formulate hypotheses, collect and analyze data, and engage with age‐tailored educational materials that support differentiated learning. We assessed the program's effectiveness through pre‐ and post‐program knowledge assessments across 1670 participants (1045 eligible responses) from the United States and Mongolia. Results showed a significant increase in knowledge acquisition in anatomy, evolution, physics, statistics, and zoology. After controlling for confounding variables, we also observed a significant increase in interest in STEM careers. Are You Stronger Than a Lemur? bridges gaps in STEM education, particularly in underrepresented fields like anatomy and evolutionary biology, by providing an adaptable program suited to different age groups, genders, and countries. Its success lies in connecting theoretical concepts to tangible data, fostering critical thinking, problem‐solving, and data interpretation skills. The program not only reinforces core STEM concepts but also offers students a unique, engaging experience that deepens their understanding and enhances their potential for future STEM careers. 

Abstract Given the many levels of biological variation in mutation rates observed to date in primates—spanning from species to individuals to genomic regions—future steps in our understanding of mutation rate evolution will not only be aided by a greater breadth of species coverage across the primate clade but also by a greater depth as afforded by an evaluation of multiple trios within individual species. In order to help bridge these gaps, we here present an analysis of a species representing one of the most basal splits on the primate tree (aye-ayes), combining whole-genome sequencing of seven parent–offspring trios from a three-generation pedigree with a novel computational pipeline that takes advantage of recently developed pan-genome graphs, thereby circumventing the application of (highly subjective) quality metrics that has previously been shown to result in notable differences in the detection of de novo mutations and ultimately estimates of mutation rates. This deep sampling has enabled both a detailed picture of parental age effects and sex dependency in mutation rates, which we here compare with previously studied primates, but has also provided unique insights into the nature of genetic variation in one of the most endangered primates on the planet. 

ABSTRACT Hantaviruses are globally distributed zoonotic pathogens capable of causing fatal disease in humans. Addressing the risk of hantavirus spillover from animal reservoirs to humans requires identifying the local reservoirs (usually rodents and other small mammals) and the predictors of infection, such as habitat characteristics and human exposure. We screened a collection of 1663 terrestrial small mammals and 227 bats for hantavirus RNA, comprised of native and non‐native species from northeastern Madagascar, trapped over 5 successive years. We specifically investigated the influence of diverse habitat types: villages, agricultural fields, regrowth areas, secondary and semi‐intact forests on infection with hantaviruses. We detected Hantavirus RNA closely related to the previously described Anjozorobe virus in 9.5% ofRattus rattussampled, with an absence of detection in other species. Land‐use had a complex impact on hantavirus infections: intensive land‐use positively correlated with the abundance ofR. rattusand the averageR. rattusbody size varied between habitats. Larger individuals had a higher probability of infection, regardless of sex. Thus, villages and pristine forests which host the smallest, and hence, least infected rats, represent the lowest risk for hantavirus exposure to people while flooded rice fields which were home to the largest rats, and subsequently most infected rats, represent the greatest exposure risk. These findings provide new insights into the relationship between rat ecology and the gradients of hantavirus exposure risk for farmers in northeastern Madagascar as they work in different land‐use types. 

Abstract Zika and dengue virus nonstructural protein 5 antagonism of STAT2, a critical interferon signaling transcription factor, to suppress the host interferon response is required for viremia and pathogenesis in a vertebrate host. This affects viral species tropism, as mouse STAT2 resistance renders only immunocompromised or humanized STAT2 mice infectable. Here, we explore how STAT2 evolution impacts antagonism. By measuring the susceptibility of 38 diverse STAT2 proteins, we demonstrate that resistance arose numerous times in mammalian evolution. In four species, resistance requires distinct sets of multiple amino acid changes that often individually disrupt STAT2 signaling. This reflects an evolutionary ridge where progressive resistance is balanced by the need to maintain STAT2 function. Furthermore, resistance may come with a fitness cost, as resistance that arose early in lemur evolution was subsequently lost in some lemur lineages. These findings underscore that while it is possible to evolve resistance to antagonism, complex evolutionary trajectories are required to avoid detrimental host fitness consequences. 

ABSTRACT Frugivore‐mediated seed dispersal drives ecological functioning across tropical forests. The biological mechanisms affecting seed dispersal outcomes, as well as the role of specific functional traits in plants and their dispersers, is still not well understood. To address this gap, we conducted germination experiments in eight species of captive and two species of wild lemurs, which disperse different plant species. We (1) quantified the effects of pulp removal, seed priming, and feces effects (nutrient/microbial fertilization) through gut passage as mechanisms, (2) determined the effect of frugivore species on germination, and (3) assessed how individual plant and animal traits affected two seed germination outcomes: success rates and time‐to‐germination. Accounting for phylogenetic non‐independence of plants and estimating phylogenetic signal, we evaluated the effects of lemur gut passage and functional traits in a Bayesian framework. Seed priming during gut passage was the primary mechanism through which lemurs improved germination rates and decreased time‐to‐germination. Gut passage influenced the effect of seed length on germination probability but not time‐to germination. Germination outcomes varied by disperser species and seed size. Furthermore, seeds passed by male lemurs were 40% more likely to germinate than those passed by female lemurs. Germination probability was more similar for closely related plant species compared to those that were more distantly related, while the plant phylogenetic effects on time‐to‐germination were weaker. Moreover, germination depended on experimental setting; for example, lemur gut passage decreased time‐to‐germination in captive, but not wild settings. Our results highlight the complexity of biological mechanisms determining seed dispersal outcomes; ecological and evolutionary factors were important drivers of germination. Considering a diversity of potential effects is critical for advancing a mechanistic understanding of species interactions and their outcomes. 

Abstract The nocturnal aye-aye, Daubentonia madagascariensis, is one of the most elusive lemurs on the island of Madagascar. The timing of its activity and arboreal lifestyle has generally made it difficult to obtain accurate assessments of population size using traditional census methods. Therefore, alternative estimates provided by population genetic inference are essential for yielding much needed information for conservation measures and for enabling ecological and evolutionary studies of this species. Here, we utilize genomic data from 17 individuals—including 5 newly sequenced, high-coverage genomes—to estimate this history. Essential to this estimation are recently published annotations of the aye-aye genome which allow for variation at putatively neutral genomic regions to be included in the estimation procedures, and regions subject to selective constraints, or in linkage to such sites, to be excluded owing to the biasing effects of selection on demographic inference. By comparing a variety of demographic estimation tools to develop a well-supported model of population history, we find strong support for two demes, separating northern Madagascar from the rest of the island. Additionally, we find that the aye-aye has experienced two severe reductions in population size. The first occurred rapidly, ∼3,000 to 5,000 years ago, and likely corresponded with the arrival of humans to Madagascar. The second occurred over the past few decades and is likely related to substantial habitat loss, suggesting that the species is still undergoing population decline and remains at great risk for extinction.