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Depression is presented as a multi-factorial bio-psycho-social expression that has evolved primarily as an effect of stressors related to the motivational/emotional systems that regulate the BrainMind in our relationship with conspecifics. These stressors may be caused by two sources of threat, firstly, the loss of bonding with the caregiver and later with a partner and/or group which relates to the SEPARATION (PANIC/GRIEF) system, secondly, social defeat as an expression of the social competition and social dominance. The sexual maturity drives the individual to social competition and social dominance, even if the latter often occurs before sexual maturity, e.g., chickens, dogs, non-human primates, and humans. Depression is an evolutionarily conserved mechanism in mammals to terminate both separation anxiety, so as to protect the vulnerable social brain from the consequences of prolonged separation anxiety, and the stress of social competition when social defeat is predictable. Adolescence and Young adulthood are particularly susceptible to these two types of threat because of human developmental characteristics that are summarized by the term neoteny. This refers to the slowing down of growth and development, resulting in both a prolonged period of dependence on a caring/protective adult and the persistence of juvenile characteristics throughout life. Therefore, neoteny makes the transition from childhood to sexual maturity more dramatic, making the integration of the SEPARATION (PANIC/GRIEF) system with the dynamics of social competition and dominance more stressful and a source of depression. Stress is an expression of the HPA-Hypothalamic-Pituitary-Adrenal axis that articulates with other systems, mainly the autonomic nervous system and the immune-inflammatory system. The latter is believed to be one of the most significant components in the dynamics of depressive processes, connected to the prodromes of its activation in childhood, under the pressure of environmental and relational stressors which can lead to learned helplessness. The recurrence of stressors makes it easier for the immune-inflammatory system to be activated in later life, which could make a significant contribution to the establishment of a depressive disease. The possible contribution of children's identification processes with their parents' depressive personalities through observational learning is considered. [ABSTRACT FROM AUTHOR]

Human-specific (HS) genes have been implicated in brain evolution, but their impact on human neuron development and diseases remains unclear. Here, we study SRGAP2B/C, two HS gene duplications of the ancestral synaptic gene SRGAP2A, in human cortical pyramidal neurons (CPNs) xenotransplanted in the mouse cortex. Downregulation of SRGAP2B/C in human CPNs led to strongly accelerated synaptic development, indicating their requirement for the neoteny that distinguishes human synaptogenesis. SRGAP2B/C genes promoted neoteny by reducing the synaptic levels of SRGAP2A,thereby increasing the postsynaptic accumulation of the SYNGAP1 protein, encoded by a major intellectual disability/autism spectrum disorder (ID/ASD) gene. Combinatorial loss-of-function experiments in vivo revealed that the tempo of synaptogenesis is set by the reciprocal antagonism between SRGAP2A and SYNGAP1, which in human CPNs is tipped toward neoteny by SRGAP2B/C. Thus, HS genes can modify the phenotypic expression of genetic mutations leading to ID/ASD through the regulation of human synaptic neoteny. [Display omitted] • Human-specific genes SRGAP2B/C are required for human cortical neuron neoteny • SRGAP2B/C slow down synaptogenesis by increasing the synaptic levels of SYNGAP1 • A tug of war between synaptic SRGAP2A and SYNGAP1 sets the tempo of synaptogenesis • SRGAP2B/C act as genetic modifiers of the function of SYNGAP1, encoded by a major ID/ASD gene Libé-Philippot et al. investigate the mechanisms underlying the prolonged synaptic development characteristic of human cortical neurons. They demonstrate that the human-specific genes SRGAP2B/C are required for human synaptic neoteny in vivo. They find that SRGAP2B/C slow down synaptogenesis by upregulating the synaptic levels of SYNGAP1, encoded by a major intellectual disability gene. [ABSTRACT FROM AUTHOR]

The genus Cheguevaria (Kazantsev 2007) is currently comprised of three species which are endemic to the Greater Antilles: Cheguevaria angustaKazantsev, 2007 (Hispaniola), Cheguevaria tainoKazantsev, 2007 and Cheguevaria montanaKazantsev, 2008 (both from Puerto Rico). Cheguevaria is the sole member of Cheguevariinae, and a previous morphology-based phylogenetic hypotheses suggested a close relationship with the subfamily Amydetinae. Recent collecting trips to Puerto Rico and the survey of other scientific collections allowed us to identify and locate more specimens of the genus, including several color morphs of specimens tentatively identified as C. montana. We used this material to revise the genus, and to describe Cheguevaria cubensisnew species, the first record of the genus from Cuba. We also produced DNA barcodes based on partial cytochrome c oxidase subunit 1 (COI), which were used to investigate the species limits within color morph species of C. montana. Our results showed a high level of genetic stability in those color morphs, indicating that all specimens belong to the same species. We present a discussion to explain possible scenarios leading to such variation in color patterns. We also generated amplicons for two specimens of Amydetinae, represented by two Amydetes Illiger, 1807 species, and we tested their relationship with Cheguevaria in a phylogenetic context based on a four gene dataset. Our analyzes indicated a disjoint relationship between Cheguevaria and Amydetes, corroborating previously published morphology-based phylogenies, and we maintained the status of Cheguevaria as an independent lineage within Lampyridae. [ABSTRACT FROM AUTHOR]

Depression is presented as a multi-factorial bio-psycho-social expression that has evolved primarily as an effect of stressors related to the motivational/emotional systems that regulate the BrainMind in our relationship with conspecifics. These stressors may be caused by two sources of threat, firstly, the loss of bonding with the caregiver and later with a partner and/or group which relates to the SEPARATION (PANIC/GRIEF) system, secondly, social defeat as an expression of the social competition and social dominance. The sexual maturity drives the individual to social competition and social dominance, even if the latter often occurs before sexual maturity, e.g., chickens, dogs, non-human primates, and humans. Depression is an evolutionarily conserved mechanism in mammals to terminate both separation anxiety, so as to protect the vulnerable social brain from the consequences of prolonged separation anxiety, and the stress of social competition when social defeat is predictable. Adolescence and Young adulthood are particularly susceptible to these two types of threat because of human developmental characteristics that are summarized by the term neoteny. This refers to the slowing down of growth and development, resulting in both a prolonged period of dependence on a caring/protective adult and the persistence of juvenile characteristics throughout life. Therefore, neoteny makes the transition from childhood to sexual maturity more dramatic, making the integration of the SEPARATION (PANIC/GRIEF) system with the dynamics of social competition and dominance more stressful and a source of depression. Stress is an expression of the HPA-Hypothalamic-Pituitary-Adrenal axis that articulates with other systems, mainly the autonomic nervous system and the immune-inflammatory system. The latter is believed to be one of the most significant components in the dynamics of depressive processes, connected to the prodromes of its activation in childhood, under the pressure of environmental and relational stressors which can lead to learned helplessness. The recurrence of stressors makes it easier for the immune-inflammatory system to be activated in later life, which could make a significant contribution to the establishment of a depressive disease. The possible contribution of children's identification processes with their parents' depressive personalities through observational learning is considered.

Molt‐based transitions in form are a central feature of insect life that have enabled adaptation to diverse and changing environments. The endocrine regulation of these transitions is well established, but an understanding of their genetic regulation has only recently emerged from insect models. The pupal and adult stages of metamorphosing insects are determined by the stage specifying transcription factors broad‐complex (br) and Ecdysone inducible protein 93 (E93), respectively. A probable larval determinant, chronologically inappropriate metamorphosis (chinmo), has just recently been characterized. Expression of these three transcription factors in the metamorphosing insects is regulated by juvenile hormone with ecdysteroid hormones, and by mutual repression between the stage‐specific transcription factors. This review explores the hypothesis that variations in the onset, duration, and tissue‐specific expression of chinmo, br, and E93 underlie other polyphenisms that have arisen throughout insects, including the castes of social insects, aquatic stages of mayflies, and the neoteny of endoparasites. The mechanisms that constrain how chinmo, br, and E93 expression may vary will also constrain the ways that insect life history may evolve. I find that four types of expression changes are associated with novel insect forms: (1) heterochronic shift in the turnover of expression, (2) expansion or contraction of expression, (3) tissue‐specific expression, and (4) redeployment of stage‐specific expression. While there is more to be learned about chinmo, br, and E93 function in diverse insect taxa, the studies outlined here show that insect stages are modular units in developmental time and a substrate for evolutionary forces to act upon. [ABSTRACT FROM AUTHOR]

Phengodidae (Coleoptera: Elateroidea), commonly known as glowworm beetles, are a small family of bioluminescent and paedomorphic beetles. There are few phylogenetic studies of Phengodidae, and these are mostly discordant, especially when comparing morphology-based and molecular-based phylogenetic hypotheses. Here, we used the anchored hybrid enrichment approach to undertake the first phylogenomic analysis of Phengodidae (≤358 loci and 39 taxa) and evaluate the higher-level classification of the group. In agreement with previous molecular studies, we recovered Phengodidae as sister to Rhagophthalmidae, and the Old World Cydistinae as sister to all New World Phengodidae. In contrast to previous hypotheses, both Phengodinae and Mastinocerinae were each recovered as monophyletic. Cenophengus was found to be sister to Mastinocerinae, in contrast to some previous hypotheses that placed it as sister to all New World Phengodidae. Considering its morphological divergence, we here establish Cenophenginae subfam. nov. Despite the largest and most comprehensive sampling of Phengodidae in any molecular-based study to date, we had only limited success in revealing the relationships among genera within the most species-rich subfamily, Mastinocerinae. Further studies should focus on the phylogeny and classification of this taxonomically neglected subfamily, on the phylogenetic placement of enigmatic Penicillophorinae, and on seeking morphological support for the main clades of Phengodidae. [ABSTRACT FROM AUTHOR]

Development consists of a highly ordered suite of steps and transitions, like choreography. Although these sequences are often evolutionarily conserved, they can display species variations in duration and speed, thereby modifying final organ size or function. Despite their evolutionary significance, the mechanisms underlying species-specific scaling of developmental tempo have remained unclear. Here, we will review recent findings that implicate global cellular mechanisms, particularly intermediary and protein metabolism, as species-specific modifiers of developmental tempo. In various systems, from somitic cell oscillations to neuronal development, metabolic pathways display species differences. These have been linked to mitochondrial metabolism, which can influence the species-specific speed of developmental transitions. Thus, intermediary metabolic pathways regulate developmental tempo together with other global processes, including proteostasis and chromatin remodeling. By linking metabolism and the evolution of developmental trajectories, these findings provide opportunities to decipher how species-specific cellular timing can influence organism fitness. Developmental trajectories are often evolutionarily conserved, yet they can display substantial temporal differences across species. In this review, Iwata and Vanderhaeghen discuss how global mechanisms, including mitochondrial metabolism and proteostasis, may contribute to interspecies differences in developmental timescales in various systems. [ABSTRACT FROM AUTHOR]

ABSTRACT Xacoxoxotlani chiapensis Ferreira new genus and new species, the second genus of the lampyrid subfamily Chespiritoinae is described from Chiapas, Mexico. The new taxon is diagnosed, illustrated and compared with Chespirito Ferreira, Keller and Branham, 2020. An updated diagnosis of the subfamily Chespiritoinae is provided along with a new identification key and distribution map for the genera and species within this subfamily.

significant body of research on the roots of human language highlights the crucial role played by changes in ancestral sociality. Recent studies have revived the hypothesis of human self-domestication, arguing that it provides new insights into the development of human sociality, cultural evolution, and symbolic communication. While the concept of domestication offers an intriguing interpretation of the co-evolution of body, cognition, and behavior, its application to human evolution is controversial. This paper explores an alternative perspective, suggesting that the enlanguagement of interactions may have acted as a catalyst for evolutionary change. We propose that the consolidation of enlanguaged practices, underpinned by the amplification of social dispositions, set in motion an evolutionary spiral. We explore how this process may have reshaped ancestral developmental trajectories and niches, ultimately culminating in the distinctive mode of life that characterizes our species. [ABSTRACT FROM AUTHOR]

The domestication of humans is not an issue of domesticity but of the effects of the domestication syndrome on a hominin species and its genome. These effects are well expressed in the ‘anatomically modern humans’, in their physiology, behavior, genetic defects, neuropathology, and distinctive neoteny. The physiological differences between modern (gracile) humans and their ancestors, robust Homo sapiens types, are all accounted for by the domestication syndrome. From deductions we can draw about early human behavior, it appears that modifications are attributable to the same cause. The domestication hypothesis ascribes the initiation of the changes to selective breeding introduced by the consistent selection of neotenous features. That would trigger genetic pleiotropy, causing the changes that are observed.

The key points of the main evolutionary line of Articulata, leading from polychaetes to insects, are considered. The far-reaching similarity of the most primitive insects, jumping bristletails, with malacostracans, especially syncarids, leaves no doubt about the origin of the former directly from the latter. The similarity of mayfly nymphs to bristletails indicates that the evolution of Pterygota began with amphibiotic Palaeoptera. Myriapods are secondarily simplified descendants of early hexapods, having lost the division of the body into the thorax and abdomen and other ancestral characters due to transition to a cryptic lifestyle. Entognathous hexapods illustrate the initial stages of myriapodization of bristletails. Following Sharov, insect ancestry can be traced back into deep time via crustaceans to trilobitomorphs, Megacheira, and further to the most ancient arthropods, dinocarids—with grasping antennae but without walking legs! Many structural features of arthropods were formed in Polychaeta—the most primitive Articulata. The group most similar to arthropods are scale worms (Aphroditacea). By analogy with myriapods and entognaths, lobopods and non-arthropodan Ecdysozoa should be interpreted as side branches, which emerged from the dinocarid root of Arthropoda and simplified their body plans. Transformations of body plans occurred through heterochronies and heterotopies (including gamoheterotopies). [ABSTRACT FROM AUTHOR]

Rhagophthalmus Motschulsky, 1854 is the most speciose genus in Rhagophthalmidae, distributed in the region encompassing South, East, and Southeast Asia. Here, we describe R. nanus sp. nov. from the Houaphanh Province of eastern Laos, which represents the smallest known species in Rhagophthalmus and one of the smallest in Rhagophthalmidae. We compare it with the morphologically similar and geographically close congeners and provide a preliminary identification key to adult males of Rhagophthalmus species from mainland Southeast Asia. Additionally, we discuss the morphology and variability of male genitalia within Rhagophthalmus. [ABSTRACT FROM AUTHOR]

Human-specific duplicated genes contributed to phenotypic innovations during the origin of our own species, such as an enlarged brain and highly developed cognitive abilities. While prior studies on transgenic mice carrying the human-specific SRGAP2C gene have shown enhanced brain connectivity, the relevance to humans remains unclear due to the significant evolutionary gap between humans and rodents. In this study, to investigate the phenotypic outcome and underlying genetic mechanism of SRGAP2C , we generated transgenic cynomolgus macaques (Macaca fascicularis) carrying the human-specific SRGAP2C gene. Longitudinal MRI imaging revealed delayed brain development with region-specific volume changes, accompanied by altered myelination levels in the temporal and occipital regions. On a cellular level, the transgenic monkeys exhibited increased deep-layer neurons during fetal neurogenesis and delayed synaptic maturation in adolescence. Moreover, transcriptome analysis detected neotenic expression in molecular pathways related to neuron ensheathment, synaptic connections, extracellular matrix and energy metabolism. Cognitively, the transgenic monkeys demonstrated improved motor planning and execution skills. Together, our findings provide new insights into the mechanisms by which the newly evolved gene shapes the unique development and circuitry of the human brain. [ABSTRACT FROM AUTHOR]

Insects are one of the few groups of animals that developed the ability of active flight. Such mobility allowed the group to successfully explore and thrive in nearly all kinds of ecological niches. At the same time, during the evolutionary history of insects, due to high costs of wing development, flight was lost independently in many groups. In beetles, the reduction or complete loss of hind wings has been reported in multiple lineages, especially in several extreme paedomorphic and larviform females, mainly in Elateroidea, in which not only the hind wings but also the elytra are lost. However, the complete absence of elytra in adult males was hitherto unknown, despite nearly half a million described species in Coleoptera. In this study, we report the discovery of Xenomorphon baranowskii gen. et sp. nov. the first completely anelytrous and wingless adult male beetle, belonging to the family Lycidae (Coleoptera: Elateroidea). Xenomorphon baranowskii is illustrated, described, and provisionally placed in Calopterini, based on our morphology-based phylogenetic analyses. We discuss the possible scenarios that could lead to such a rare event, when a beetle loses its elytra, and its evolutionary consequences. [ABSTRACT FROM AUTHOR]

Definition: The domestication of humans is not an issue of domesticity but of the effects of the domestication syndrome on a hominin species and its genome. These effects are well expressed in the 'anatomically modern humans', in their physiology, behavior, genetic defects, neuropathology, and distinctive neoteny. The physiological differences between modern (gracile) humans and their ancestors, robust Homo sapiens types, are all accounted for by the domestication syndrome. From deductions we can draw about early human behavior, it appears that modifications are attributable to the same cause. The domestication hypothesis ascribes the initiation of the changes to selective breeding introduced by the consistent selection of neotenous features. That would trigger genetic pleiotropy, causing the changes that are observed. [ABSTRACT FROM AUTHOR]

A juvenile of Rhinopias cf. argoliba 28 mm SL collected in the western part of the Pacific Ocean eastward of the Philippines is described. It is characterized by an incomplete metamorphosis with some larval characters retained such as the developed spination and relatively straight dorsal contour of the head, absence of the scales and the branched fin rays (except in pelvic fins), and a long penultimate dorsal-fin spine. Comparison of this juvenile with juveniles of R. aphanes 11–22 mm SL reveals the diagnostic importance of the pigmentation of the pectoral fin which disappears in the adult fishes. A possible synonymy of the genera Rhinopias and Pogonoscorpius was repeatedly supposed by the former authors. The poorly-known Pogonoscorpius sechellensis retains the features characteristic for the species of Rhinopias from the earliest ontogenetic stages only, and probably represents a neotenic species of the latter genus. [ABSTRACT FROM AUTHOR]

Xenos vesparum of the highly specialized Strepsiptera is a new insect model in the context of host-parasite relationships. The endoparasitic female and male secondary larvae were studied using µCT, 3D-reconstructions, histology, and photomicrography. The infectious primary larva is followed by a trophic and endoparasitic secondary larval stage. In contrast to immature stages of other holometabolous groups, the second instar increases dramatically in size. Compound eyes and external wing anlagen are present in male larvae before the pupal stage. In contrast to the females, the brain of males bears well-developed optic neuropils and retinula cells are present. The cephalothorax is comparatively simple in the female larvae, yet distinctly more complex than in the adult, where most muscles are reduced. Large testes are present in male larvae and numerous oocytes in the females, but they are still immature. The larval features are discussed in the context of holome-tabolous development and heterochronic processes. Unique features of Strepsiptera are the early differentiation of the sexes and the occurrence of compound eyes and external wing anlagen in male secondary larvae. The phylogenetic position of Strepsiptera suggests that this is a secondary feature and thus an autapomorphy. To address mature females of Stylopidia as neotenic adults is an oversimplification. They display a mosaic pattern of paedomorphic characters such as features of the nervous system and the presence of stemmata, but also non-paedomorphic structures, such as the spiracles. [ABSTRACT FROM AUTHOR]

Pet-directed speech (PDS) is often produced by humans when addressing dogs. Similar to infant-directed speech, PDS is marked by a relatively higher and more modulated fundamental frequency (f0) than is adult-directed speech. We tested the prediction that increasing eye size in dogs, one facial feature of neoteny (juvenilisation), would elicit exaggerated prosodic qualities or pet-directed speech. We experimentally manipulated eye size in photographs of twelve dog breeds by −15%, +15% and +30%. We first showed that dogs with larger eyes were indeed perceived as younger. We then recorded men and women speaking towards these photographs, who also rated these images for cuteness. Linear mixed-effects models demonstrated that increasing eye size by 15% significantly increased pitch range (f0 range) and variability (f0CV) among women only. Cuteness ratings did not vary with eye size, due to a possible ceiling effect across eye sizes. Our results offer preliminary evidence that large eyes can elicit pet-directed speech and suggest that PDS may be modulated by perceived juvenility rather than cuteness. We discuss these findings in the context of inter-species vocal communication. [ABSTRACT FROM AUTHOR]

The relative independence of ontogenetic processes, which is characteristic of amphibians, determines the possibility of shifts in the rate and timing of the ontogenetic events, or heterochronies. Heterochronies give rise to ontogenetic and morphological diversity in amphibians, which can occur without significant genetic changes. Heterochrony-related neoteny, miniaturization and paedomorphic underdevelopment, as well as loss of ancestral traits due to their transition into a latent capacities state with the possibility of secondary recapitulation are phenomena typical of both recent and fossil amphibians. [ABSTRACT FROM AUTHOR]

This article discusses theoretical aspects of studies on viviparous organisms and provides new approaches to understanding the evolution of viviparity. Viviparity is considered here not as a "great biological advantage," but as the simplest way of birth, that in terms of biodiversity is in the minority; it is realized only in cases in which, due to various reasons, laying eggs is impossible or poorly compatible with newly acquired morphological and/or physiological characteristics. Aberrations of the reproductive sphere, changes in its ancestral state and changes leading to viviparity, can be divided into three main groups: (1) the appearance of oogamy in the ancient colonial protists and multicellular organisms before the appearance of any mechanisms for extrusion of immobile oogamete (or zigote); (2) evolutionary conversions from external to internal fertilization in organisms that have no specialized oviducts with accessory glands and spermathecae; (3) abnormalities in well-developed female reproductive systems: the loss of insect reproductive organs (in cases of paedogenesis, neoteny, or paedomoprhosis), larval meiosis, change of fertilization area from ectodermal parts of oviducts to intragonadal fertilization. All the above mentioned evolutionary rearrangements are considered from the point of view of an analytical review of viviparity in the largest biological taxa from archaic multicellular organisms to the most advanced groups of invertebrate and vertebrate animals. [ABSTRACT FROM AUTHOR]

Simple Summary: In a broad sense, "paedomorphosis" refers to the similarity within a species between the adult form and its juvenile counterpart, as seen in certain species such as dogs and cats. Yet in horse breeds, the study of phenotypic characteristics in juveniles primarily focuses on body and limb proportions, e.g., distal limb length. Conversely, in the Purebred Arabian Horse (PAH), the juvenile form is clearly representational in the adult, and in particular, the phenotypic characteristics of the head. In this study, we investigate paedomorphosis by examining the left lateral profile of the head from photographs of PAH and first-generation crossbred PAHs (F1 crossbreds). This enabled a somewhat consistent image to be examined. By utilizing methods of geometric morphometry, a set of 23 semi-landmarks were studied that defined the profile of the head. The results implied the concave profile of the juvenile remained consistent with age and, therefore, there is a retention of juvenile traits into adulthood. This suggests that PAHs and F1 crossbreds could be considered paedomorphic-like animals. This study examined paedomorphosis in PAH and F1 crossbreds. A sample of 99 horses was selected from 40 different breeders and consisted of three groups: stallions (n = 16), mares (n = 53), and geldings (n = 30), ranging from 10 months to 27 years in age. All horses presented a concave celloid lateral left head profile in the acquired photographic images. The hypothesis proposed in this study suggested the lateral profile of the head in juveniles was representational in the adult form due to the neonate's facial bones (part of the splanchnocranium) developing at a different rate to those of the skull. The methodology utilized geometric morphometrics to identify 23 landmarks so as to identify profile curvature indicative between the three groups (stallions, mares, and geldings). Principal component analysis reduced the number of variables to 14 examinable landmarks. Using a two-NPMANOVA and multivariate regression test, it was demonstrated that an isometric relationship between the concave celloid profile in the juvenile and its adult counterpart existed. This result supported the hypothesis that PAH and F1 crossbreds expressed a paedomorphic trait due to the adult form retaining the concave celloid profile identified in the juvenile. [ABSTRACT FROM AUTHOR]

Rhagophthalmidae are a small beetle family known from the eastern Palaearctic and Oriental realms. Rhagophthalmidae are closely related to railroad worms (Phengodidae) and fireflies (Lampyridae) with which they share highly modified paedomorphic females and the ability to emit light. Currently, Rhagophthalmidae include 66 species classified in the following 12 genera: Bicladodrilus Pic, 1921 (two spp.), Bicladum Pic, 1921 (two spp.), Dioptoma Pascoe, 1860 (two spp.), Diplocladon Gorham, 1883 (two spp.), Dodecatoma Westwood, 1849 (eight spp.), Falsophrixothrix Pic, 1937 (six spp.), Haplocladon Gorham, 1883 (two spp.), Menghuoius Kawashima, 2000 (three spp.), Mimoochotyra Pic, 1937 (one sp.), Monodrilus Pic, 1921 (two spp. in two subgenera), Pseudothilmanus Pic, 1918 (two spp.), and Rhagophthalmus Motschulsky, 1854 (34 spp.). The replacement name Haplocladon gorhami Kundrata, nom. nov. is proposed for Diplocladon hasseltii Gorham, 1883b (described in subgenus Haplocladon) which is preoccupied by Diplocladon hasseltii Gorham, 1883a. The genus Reductodrilus Pic, 1943 is tentatively placed in Lampyridae: Ototretinae. Lectotypes are designated for Pseudothilmanus alatus Pic, 1918 and P. marginalis Pic, 1918. Interestingly, in the eastern part of their distribution, Rhagophthalmidae have remained within the boundaries of the Sunda Shelf and the Philippines demarcated by the Wallace Line, which separates the Oriental and Australasian realms. This study is intended to be a first step towards a comprehensive revision of the group on both genus and species levels. Additionally, critical problems and prospects for rhagophthalmid research are briefly discussed. [ABSTRACT FROM AUTHOR]

Simple Summary: The genus Malacogaster Bassi, 1834 belongs to the soft-bodied click-beetle tribe Drilini which contain species with a strong sexual dimorphism—while males are fully winged and able to fly, females are wingless and remain larviform. Malacogaster is known from the Mediterranean region, ranging from the Canary Islands and Iberian Peninsula on the west to Sicily and Libya on the east. In this study, we collated for the first time all information on this enigmatic click-beetle genus and all its species. We provide figures for all available name-bearing type specimens, redescribe species, and discuss their morphology, variability, and distribution. Although several species are readily recognizable based on the morphology and coloration, limits of some other species need further investigation including the DNA-based approach. The soft-bodied click-beetle genus Malacogaster Bassi, 1834 from the Mediterranean region has never been taxonomically revised to date. Information on its morphology, intra- and interspecific variability, systematics and distribution is fragmented and most species have not been properly studied since their description. Therefore, in this study we summarize all available information on the genus Malacogaster. Altogether, we recognize 10 valid species from the area including the Canary Islands, Iberian Peninsula, Balearic Islands, northern coast of Africa, Sardinia, and Sicily. Malacogaster ruficollis Dodero, 1925, stat. nov., which was originally described as a variety of M. bassii Lucas, 1870 and later synonymized with it, is considered a separate species. Malacogaster parallelocollis Reitter, 1894, syn. nov. and M. olcesei var. reductus Pic, 1951, syn. nov. are synonymized with M. maculiventris Reitter, 1894. Malacogaster notativentris Pic, 1951, syn. nov. and M. olcesei Pic, 1951, syn. nov. are synonymized with M. passerinii Bassi, 1834. Lectotypes are designated for M. maculiventris Reitter, 1894, M. nigripes heydeni Reitter, 1894, M. parallelocollis Reitter, 1894, M. thoracica Redtenbacher, 1858, M. olcesei Pic, 1951, and M. rubripes Peyerimhoff, 1949 to fix their identity. [ABSTRACT FROM AUTHOR]

Naked mole rats (NMRs) are the longest‐lived rodents yet their stem cell characteristics remain enigmatic. Here, we comprehensively mapped the NMR hematopoietic landscape and identified unique features likely contributing to longevity. Adult NMRs form red blood cells in spleen and marrow, which comprise a myeloid bias toward granulopoiesis together with decreased B‐lymphopoiesis. Remarkably, youthful blood and marrow single‐cell transcriptomes and cell compositions are largely maintained until at least middle age. Similar to primates, the primitive stem and progenitor cell (HSPC) compartment is marked by CD34 and THY1. Stem cell polarity is seen for Tubulin but not CDC42, and is not lost until 12 years of age. HSPC respiration rates are as low as in purified human stem cells, in concert with a strong expression signature for fatty acid metabolism. The pool of quiescent stem cells is higher than in mice, and the cell cycle of hematopoietic cells is prolonged. By characterizing the NMR hematopoietic landscape, we identified resilience phenotypes such as an increased quiescent HSPC compartment, absence of age‐related decline, and neotenic traits likely geared toward longevity. Synopsis: Naked mole‐rats are the longest‐lived rodents but their hematopoietic system and contained self‐renewing stem cell populations remain poorly characterized. Combining surface marker and sequencing analysis, this resource reports the first comprehensive map of the naked mole‐rat blood system, uncovering similarities to their human counterpart during ageing. A cross‐reactive FACS antibody panel allows for purification of naked mole‐rat stem, progenitor and effector cells from blood, spleen and bone marrow.Red blood cells are produced in both bone marrow and spleen, exemplifying a neotenic trait.Enlargement of the myeloid compartment and concomitantly reduced B‐lymphopoiesis in the bone marrow resemble fetal stages of white blood cell production.CD34 marks the primitive stem and progenitor compartment, similar as in humans.An enlarged quiescent stem cell pool preserves hematopoiesis during an extended lifespan.Stem and progenitor cells feature a prolonged cell cycle in vivo, with a low metabolic profile and elevated lipid metabolism. [ABSTRACT FROM AUTHOR]

Evolutionary medicine studies the role of evolution in health problems. Diseases are considered as phenotypes generated by the expression of sets of genes and a complex interplay with the environment. The main mechanisms involved in evolutionary medicine are antagonistic pleiotropy, ecological antagonistic pleiotropy, atavisms and heterochrony. Antagonistic pleiotropism refers to genes that are beneficial during certain stages of development but become detrimental in others. Ecological antagonistic pleiotropy refers to the misadaptation to current lifestyle conditions which are different from those in which humans evolved. These mechanisms participate in the development of congestive heart failure, hypertension and atherosclerosis. Atavistic conditions or genes are expressed in our ancestors but have remained silent during evolution being suddenly expressed without an apparent cause during the appearance of a disease is another mechanism in evolutionary cardiology. The change in the heart metabolism from fatty acid to glucose dependent can be considered as an atavistic condition that appears in the heart after a stroke and may underlie impaired cardiomyocyte regeneration. Heterochrony is the expression of genes that cause the appearance of traits at a different timing during development and is therefore related to atavisms. Evolutionary medicine explains the interactions of pathogens and the host in infectious diseases where the cardiac tissue becomes a target. Mechanisms involved in evolutionary medicine participate in the generation of diseases and may be approached experimentally. Therefore, to better understand health problems and therapeutical approaches, an evolutionary medicine approach in experimental medicine may prove useful. [ABSTRACT FROM AUTHOR]

Human brain ontogeny is characterized by a considerably prolonged neotenic development of cortical neurons and circuits. Neoteny is thought to be essential for the acquisition of advanced cognitive functions, which are typically altered in intellectual disability (ID) and autism spectrum disorders (ASDs). Human neuronal neoteny could be disrupted in some forms of ID and/or ASDs, but this has never been tested. Here, we use xenotransplantation of human cortical neurons into the mouse brain to model SYNGAP1 haploinsufficiency, one of the most prevalent genetic causes of ID/ASDs. We find that SYNGAP1-deficient human neurons display strong acceleration of morphological and functional synaptic formation and maturation alongside disrupted synaptic plasticity. At the circuit level, SYNGAP1-haploinsufficient neurons display precocious acquisition of responsiveness to visual stimulation months ahead of time. Our findings indicate that SYNGAP1 is required cell autonomously for human neuronal neoteny, providing novel links between human-specific developmental mechanisms and ID/ASDs. [Display omitted] • SYNGAP1 is required cell autonomously for human synaptic neoteny • SYNGAP1 deficiency leads to precocious sensory responses in human cortical neurons • ID/ASD are directly linked to disrupted neoteny in human cortical neurons in vivo • In vivo modeling of a neurodevelopmental disease in human neurons at the circuit level Vermaercke et al. investigate the mechanisms underlying deficiency in the ID/ASD gene SYNGAP1 in human cortical neurons transplanted in the mouse cortex. They find that SYNGAP1-deficient neurons develop mature synapses and circuit integration months in advance, leading to precocious sensory responsiveness. These data link disrupted neoteny of human neurons to an ID/ASD gene mutation. [ABSTRACT FROM AUTHOR]

Unique aspects of human behavior are often attributed to differences in the relative size and organization of the human brain: these structural aspects originate during early development. Recent studies indicate that human neurodevelopment is considerably slower than that in other nonhuman primates, a finding that is termed neoteny. One aspect of neoteny is the slow onset of action potentials. However, which molecular mechanisms play a role in this process remain unclear. To examine the evolutionary constraints on the rate of neuronal maturation, we have generated transcriptional data tracking five time points, from the neural progenitor state to 8-week-old neurons, in primates spanning the catarrhine lineage, including Macaca mulatta , Gorilla gorilla , Pan paniscus , Pan troglodytes , and Homo sapiens. Despite finding an overall similarity of many transcriptional signatures, species-specific and clade-specific distinctions were observed. Among the genes that exhibited human-specific regulation, we identified a key pioneer transcription factor, GATA3 , that was uniquely upregulated in humans during the neuronal maturation process. We further examined the regulatory nature of GATA3 in human cells and observed that downregulation quickened the speed of developing spontaneous action potentials, thereby modulating the human neotenic phenotype. These results provide evidence for the divergence of gene regulation as a key molecular mechanism underlying human neoteny. • GATA3 is upregulated in human maturing neurons compared with nonhuman primates • Downregulation of GATA3 increased the rate of action potentials in human neurons • GATA3-binding sites are under positive selective pressure in human neurons • The divergence of GATA3 regulation in human neurons contributes to human neoteny Linker et al. report that the pioneer transcription factor GATA3 is specifically upregulated in human maturing neurons compared with four species of nonhuman primates and is correlated to a slower development of action potentials. The results provide evidence for the divergence of gene regulation as a key molecular mechanism underlying human neoteny. [ABSTRACT FROM AUTHOR]

Distinct life stages may experience different selection pressures influencing phenotypic evolution. Morphological evolution is also constrained by early phenotypes, since early development forms the phenotypic basis of later development. This work investigates evolutionary-developmental modification in three life stages and both sexes of 24 Rhipicephalus species using phylogenetic comparative methods for geometric morphometrics of basis capituli (basal mouthpart structure used for host attachment), and scutum or conscutum areas (proxy for overall body size). Findings indicate species using large hosts at early life stages have distinct basis capituli shapes, correlated with host size, enabling attachment to the tough skins of large hosts. Host-truncate species (one- and two-host) generally retain these adaptive features into later life stages, suggesting neoteny is linked to the evolution of host truncation. In contrast, species using small hosts at early life stages have lost these features. Developmental trajectories differ significantly between host-use strategies (niches), and correlate with distinct clades. In two-host and three-host species using large hosts at early life stages, developmental change is heterotopically accelerated (greater cell mass development) before the first off-host period where selection probably favours large individuals able to better resist dehydration when questing (waiting) for less abundant, less active hosts. In other species, development is heterotopically reduced (neotenic), possibly because dehydration risk is bypassed by prolonged host attachment (one-host species – heterotopic neoteny), or is allometrically repatterned possibly by using highly abundant and active hosts (three-host species using small hosts at early life stages – allometric repatterning). These findings highlight complex trade-offs between on- and off-host factors of free-living ectoparasite ecology, which mediate responses to diverse selection pressures varied by life stage and host-use strategy. It is proposed that these trade-offs shape evolutionary-developmental morphology and diversity of Rhipicephalus ticks. [Display omitted] • Species using large hosts at early life stages have distinct basis capituli to facilitate attachment to large hosts. • Evolutionary modulation of developmental trajectories respond to on- and off-host conditions between host-use strategies. • Neoteny occurs in host-truncate species, likely as adaptive responses to selection for using large hosts at early life stages. [ABSTRACT FROM AUTHOR]