Male Tree Research Articles

Whole-genome DNA methylomes of Tree shrew brains reveal conserved and divergent roles of DNA methylation on sex chromosome regulation.

The tree shrew (Tupaia belangeri) is a promising emerging model organism in biomedical studies, notably due to their evolutionary proximity to primates. To enhance our understanding of how DNA methylation is implicated in regulation of gene expression and the X chromosome inactivation (XCI) in tree shrew brains, here we present their first genome-wide, single-base-resolution methylomes integrated with transcriptomes from prefrontal cortices. We discovered both divergent and conserved features of tree shrew DNA methylation compared to that of other mammals. DNA methylation levels of promoter and gene body regions are negatively correlated with gene expression, consistent with patterns in other mammalian brains studied. Comparing DNA methylation patterns of the female and male X chromosomes, we observed a clear and significant global reduction (hypomethylation) of DNA methylation across the entire X chromosome in females. Our data suggests that the female X hypomethylation does not directly contribute to the gene silencing of the inactivated X chromosome nor does it significantly drive sex-specific gene expression of tree shrews. However, we identified a putative regulatory region in the 5' end of the X inactive specific transcript (Xist) gene, a key gene for XCI, whose pattern of differential DNA methylation strongly relate to its differential expression between male and female tree shrews. We show that differential methylation of this region is conserved across different species. Moreover, we provide evidence suggesting that the observed difference between human and tree shrew X-linked promoter methylation is associated with the difference in genomic CpG contents. Our study offers novel information on genomic DNA methylation of tree shrews, as well as insights into the evolution of X chromosome regulation in mammals.

Identification of Sex-Associated Genetic Markers in Pistacia lentiscus var. chia for Early Male Detection.

Pistacia lentiscus var. chia is a valuable crop for its high-added-value mastic, a resin with proven pharmaceutical and cosmeceutical properties harvested from the male tree trunk. To achieve the maximum economic benefits from the cultivation of male mastic trees, it is important to develop early sex diagnosis molecular tools for distinguishing the sex type. Thus far, the work on sex identification has focused on Pistacia vera with promising results; however, the low transferability rates of these markers in P. lentiscus necessitates the development of species-specific sex-linked markers for P. lentiscus var. chia. To our knowledge, this is the first report regarding: (i) the development of species-specific novel transcriptome-based markers for P. lentiscus var. chia and their assessment on male, female and monoecious individuals using PCR-HRM analysis, thus, introducing a cost-effective method for sex identification with high accuracy that can be applied with minimum infrastructure, (ii) the effective sex identification in mastic tree using a combination of different sex-linked ISSR and SCAR markers with 100% accuracy, and (iii) the impact evaluation of sex type on the genetic diversity of different P. lentiscus var. chia cultivars. The results of this study are expected to provide species-specific markers for accurate sex identification that could contribute to the selection process of male mastic trees at an early stage for mass propagation systems and to facilitate future breeding efforts related to sex-linked productivity and quality of mastic resin.

High temperature during photorefractory stage attenuates photoperiodic responses during photostimulatory stage in male tree sparrows (Passer montanus)

Photoperiod is the most reliable environmental cue, though other environmental factors may affect breeding. We hypothesized that exposure to high temperatures at the photorefractory stage suppresses photoperiodic responses during the photostimulatory phase. Male adult photorefractory tree sparrows (n=10/group) were exposed to short photoperiod (SD;16 L:8D) but either high (30 ± 2 0C) or low temperature (20 ± 2 0C) for five or seven weeks and then long photoperiod (LD; 16 L:8D) for 30 days. mRNA levels of thyroid-stimulating hormone-β (Tshβ), type 2 deiodinase (Dio2), type 3 deiodinase (Dio3), gonadotropin-releasing hormone (GnRh), gonadotropin inhibitory hormone (GnIh), and EYA transcriptional coactivator and phosphatase 3 (Eya3) were measured in hypothalamic and expression levels of StAR, ER, CYP17, CYP11B, FOXOL1, and Nr4A1 were measured in the testes. Results show that exposure to 5 weeks of high temperature coupled with Short days suppresses expression of Tshβ, Dio2, and GnRh in the hypothalamus and StAR, ER, CYP17A1, and CYP11B in the testes under long days. No such effects were observed in birds exposed to high temperatures along with SD for seven weeks. These findings suggest that exposure to high temperature during the photorefractory stage modulates photoperiodic responses during the photostimulatory stage in time dependent manner.

Aśvattha and śamī. The Evolution of the Meanings of an Arboreal Couple in Indian Religious History

In this article I will explore some mythological and ritual aspects related to a pair of trees, the aśvattha and the śamī. In India, since the time of the Vedic culture, these two trees have often been the protagonists of myths and rituals in which they are conceived of as a couple. In various contemporary religious contexts, one finds dendrolatric practices (vanaspatipūjā), which sometimes result in the celebration of actual tree marriages (vr̥kṣa vivāha), whereby trees grow by intertwining with each other. The aśvattha and the śamī, though in today's context separately, are also subject to dendrogamic practices. In particular, the aśvattha is subject to a gender-shift whereby in some contexts, though traditionally regarded as the male tree, it acquires a female role within the couple. This phenomenon finds a parallel in various myths and rituals handed down in the Vedic texts. In fact, the araṇis, that is, the two sticks that were rubbed together during the ritual of lighting the fire, were made from the wood of the two trees. The analysis of the symbolic values linked to the coupling of the two araṇis and the many variants that this motif generated allows us to highlight, on a mythical level, the emergence of a sexuality that is not necessarily heteronormative. These versions, in fact, lead us to reflect on an arboreal nature that alludes to a sexuality that bypasses and transcends the gender binary and accounts for the fluidity found in certain contemporary arboreal ‘marriages.

Innate Immune-Enhancing Effect of Pinus densiflora Pollen Extract via NF-κB Pathway Activation.

Considering the emergence of various infectious diseases, including the coronavirus disease 2019 (COVID-19), people's attention has shifted towards immune health. Consequently, immune-enhancing functional foods have been increasingly consumed. Hence, developing new immune-enhancing functional food products is needed. Pinus densiflora pollen can be collected from the male red pine tree, which is commonly found in Korea. P. densiflora pollen extract (PDE), obtained by water extraction, contained polyphenols (216.29 ± 0.22 mg GAE/100 g) and flavonoids (35.14 ± 0.04 mg CE/100 g). PDE significantly increased the production of nitric oxide (NO) and reactive oxygen species (ROS) but, did not exhibit cytotoxicity in RAW 264.7 cells. Western blot results indicated that PDE induced the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2. PDE also significantly increased the mRNA and protein levels of cytokines and the phosphorylation of IKKα/β and p65, as well as the activation and degradation of IκBα. Additionally, western blot analysis of cytosolic and nuclear fractions and immunofluorescence assay confirmed that the translocation of p65 to the nucleus after PDE treatment. These results confirmed that PDE increases the production of cytokines, NO, and ROS by activating NF-κB. Therefore, PDE is a promising nutraceutical candidate for immune-enhancing functional foods.

Exaggerated mandibles are correlated with enhanced foraging efficacy in male Auckland tree wētā.

Sexual selection has driven the evolution of weaponry for males to fight rivals to gain access to females. Although weapons are predicted to increase males' reproductive success, they are also expected to incur costs and may impair functional activities, including foraging. Using feeding assays, we tested whether the enlarged mandibles of Auckland tree wētā (Hemideina thoracica) impact feeding activity (the total volume of biomass consumed, bite rate, and number of foraging visits) and foraging behaviour (time spent moving, feeding, or stationary). We predicted that increased head capsule size in male wētā would hinder their foraging efficacy. However, we found that wētā with longer heads fed at a faster rate and spent less time foraging than wētā with smaller heads, regardless of sex. Contrary to expectations that weapons impede functional activities, our results demonstrate that exaggerated traits can improve feeding performance and may offer benefits other than increased mating success.

Sex-determining region complements traditionally used in phylogenetic studies nuclear and chloroplast sequences in investigation of Aigeiros Duby and Tacamahaca Spach poplars (genus Populus L., Salicaceae).

Members of the genus Populus L. play an important role in the formation of forests in the northern hemisphere and are used in urban landscaping and timber production. Populus species of closely related sections show extensive hybridization. Therefore, the systematics of the genus is rather complicated, especially for poplars of hybrid origin. We aimed to assess the efficiency of application of the sex-determining region (SDR) in addition to the nuclear and chloroplast genome loci traditionally used in phylogenetic studies of poplars to investigate relationships in sections Aigeiros Duby and Tacamahaca Spach. Targeted deep sequencing of NTS 5S rDNA, ITS, DSH 2, DSH 5, DSH 8, DSH 12, DSH 29, 6, 15, 16, X18, trnG-psbK-psbI, rps2-rpoC2, rpoC2-rpoC1, as well as SDR and ARR17 gene was performed for 379 poplars. The SDR and ARR17 gene together with traditionally used multicopy and single-copy loci of nuclear and chloroplast DNA allowed us to obtain a clustering that is most consistent with poplar systematics based on morphological data and to shed light on several controversial hypotheses about the origin of the studied taxa (for example, the inexpediency of separating P. koreana, P. maximowiczii, and P. suaveolens into different species). We present a scheme of relationships between species and hybrids of sections Aigeiros and Tacamahaca based on molecular genetic, morphological, and geographical data. The geographical proximity of species and, therefore, the possibility of hybridization between them appear to be more important than the affiliation of species to the same section. We speculate that sections Aigeiros and Tacamahaca are distinguished primarily on an ecological principle (plain and mountain poplars) rather than on a genetic basis. Joint analysis of sequencing data for the SDR and chloroplast genome loci allowed us to determine the ancestors of P. × petrovskoe - P. laurifolia (female tree) × P. × canadensis (male tree), and P. × rasumovskoe - P. nigra (female tree) × P. suaveolens (male tree). Thus, the efficiency of using the SDR for the study of poplars of sections Aigeiros and Tacamahaca and the prospects of its use for the investigation of species of the genus Populus were shown.

Expression of Testis-specific Serine/Threonine Kinases during the Reproductive and Nonreproductive Seasons and Their Localization in Mature Spermatozoa of Tree Shrews (Tupaia belangeri).

Tree shrews display obvious reproductive cycles, and sexually mature male tree shrews produce little or no sperm with extremely low motility during the nonreproductive season; the mechanism underlying this phenomenon remains unknown. Because testis-specific serine/threonine kinases (TSSK) are specifically expressed in the testis and male germ cells of mammals, we hypothesized that they may have an important role in spermatogenesis or sperm function regulation in tree shrews. In addition, the expression, distribution, subcellular localization, and dynamic changes of TSSK in tree shrew sperm are unclear. Here we show that during the reproductive season, the seminiferous tubules were significantly larger as compared with the nonreproductive season and contained mature sperm and other germ cells. The mRNA expression of Tssk genes in testis was significantly higher than that in other tissues, and the mRNA level in the testis during the reproductive season was significantly higher than that in nonreproductive season. In addition, the mRNA level of Tssk3 in the testis and sperm was significantly higher than that of other members. Specifically, Tssk1 mRNA was distributed in the acrosome and throughout the flagellum of tree shrew sperm, Tssk2 was present in the acrosome, Tssk3 was localized to postacrosomal region and relocated to the main part of the flagellum after capacitation, and Tssk6 was distributed in the acrosome and postacrosomal region. These results indicate that the TSSK are important regulating reproductive function in tree shrews.

The tree shrew as a new animal model for the study of periodontitis.

Periodontitis is an inflammatory, infectious disease of polymicrobial origin that can damage tooth-supporting bone and tissue. Tree shrews, evolutionarily closer to humans than commonly used rodent models, have been increasingly used as biomedical models. However, a tree shrew periodontitis model has not yet been established. Periodontitis was induced in male tree shrews/Sprague-Dawley rats by nylon thread ligature placement around the lower first molars. Thereafter, morphometric and histological analyses were performed. The distance from the cemento-enamel junction to the alveolar bone crest was measured using micro-computed tomography. Periodontal pathological tissue damage, inflammation and osteoclastogenesis were assessed using haematoxylin and eosin staining and quantitative immunohistochemistry, respectively. Post-operatively, gingival swelling, redness and spontaneous bleeding were observed in tree shrews but not in rats. After peaking, bone resorption decreased gradually until plateauing in tree shrews. Contrastingly, rapid and near-complete bone loss was observed in rats. Inflammatory infiltrates were observed 1 week post operation in both models. However, only the tree shrew model transitioned from acute to chronic inflammation. Our study revealed that a ligature-induced tree shrew model of periodontitis partly reproduced the pathological features of human periodontitis and provided theoretical support for using tree shrews as a potential model for human periodontitis.

Male nuptial display colour and vocalisation appear to signal independent information in the whirring tree frog

When different modes of communication are used in combination and for example convey visual and acoustic information, they form a multimodal signal. Frogs are best known for using acoustic communication, but many species also use visual or colour signals, some of which are dynamic, and may be combined with acoustic signals. In this context, the question of whether these two modes of communication reinforce the same message or offer different information is poorly understood. Male whirring tree frogs, Litoria revelata, use a multimodal signal during courtship, which combines a vocalisation and dynamic sexual dichromatism, with nuptial display colours shifting from brown or grey to bright yellow. Here, we examined the properties of the advertisement call and nuptial colour of vocalising male whirring tree frogs and tested whether the two signals were likely to reinforce each other or convey independent information. We found only weak associations between elements of male colouration and vocalisations, suggesting that advertisement calls and nuptial colour do not reinforce each other and that the signals may instead convey different information.Significance statementDynamic nuptial colour and vocalisation in combination is a relatively common multimodal signal in frogs but is unstudied. We looked for relationships between properties of colour and vocalisation in an Australian tree frog to explore whether the two sensory modes formed backup signals or multiple messages. We did not find predictive relationships between nuptial colour and vocalisation, supporting the multiple messages hypothesis and suggesting that nuptial colour is not necessarily directed at females for the purposes of mate attraction, potentially differing from the assumed function of the vocalisation. Our study is also the first to formally characterise aspects of dynamic sexual dichromatism in the whirring tree frog (Litoria revelata) and the first to describe the advertisement call of this species in its southern distribution. Whilst we do not specifically address the function of dynamic sexual dichromatism in this species, our findings do not contradict the existing literature in respect to it being a male-male directed signal.

Intraspecific variation in advertisement call characteristics and acoustic strategies among male forest green tree frogs

AbstractFrogs are a representative taxon that use advertisement calls to aid in reproduction. In most frog species, calls vary with body size, and allometric constraints between body size and call frequency have been widely reported among anuran species. Although this variation is an important driver of sexual selection in frogs, male advertisement call strategies may also vary according to body size. In this study, we conducted playback experiments on the male forest green tree frog (Zhangixalus arboreus) to determine whether male advertisement call characteristics and strategies vary according to body size and the amplitude of intraspecific chorus noise. The results indicated that the calls of larger individuals are louder and lower than those of smaller ones, who call more frequently; moreover, the calls become lower, and the number of calls decreases, as noise levels increase. These findings suggest that forest green tree frog emits lower calls or refrains from calling when chorus noise increases, and that intraspecific variation in advertisement call characteristics can induce different strategies in response to chorus noise. Because advertisement call variation with body size is common among frog species, intraspecific variation in male advertisement call strategies may also be a common phenomenon.

Potential and Constraints on In Vitro Micropropagation of Juniperus drupacea Labill.

Juniperus drupacea Labill. (Cupressaceae) is a species with ecological and medicinal value. In Europe, it is native only in southern Greece, and is listed as endangered. Due to its uniqueness, this study attempted, for the first time, an in vitro propagation effort of Syrian juniper. Explants of the lateral shoot tips were surface-sterilized and cultured on Murashige and Skoog (MS) medium. The cultures were subcultured on MS, woody plant medium (WPM), and Driver and Kuniyaki Walnut (DKW) supplemented with different concentrations of 6-benzylaminopurine (BA), thidiazuron (TDZ), or meta-topolin [6-(3-hy-droxybenzylamino)purine] for shoot induction. Explants derived from female trees exhibited 54.17% bud proliferation on DKW medium with 4 μM meta-topolin or 4 μM TDZ and on WPM with 4 μM meta-topolin or 4 μM BA. A total of 62.50% of the male tree derived explants produced multiple shoots on DKW with 4 μM BA. The maximum average number of shoots per explant were 1.17 per explant in both cases. The length of the shoot derived from explants of female origin was 2.94 mm compared to 2.69 mm of the in vitro shoots from the explants of male trees. Overall, the best medium and plant growth regulator combination for the explants derived from both female and male trees, for the traits under study, was proven to be DKW + 4 µM TDZ. Our experiments show that Juniperus drupacea, under in vitro conditions, shows recalcitrance in rooting, as the applications of IBA, NAA, and IAA concentrations were proven to be ineffective treatments. Although the results show low values, this avant-garde study provides a foundation for further research on the in vitro regeneration of Juniperus drupacea.

The differences in cocoon and silk qualities among sex-related mulberry and silkworm feeding groups.

Sexual dimorphism is seen in many dioecious plant and animal species, which may influence their trophic interactions. The differences in trophic interactions derived from sexual dimorphism in plants may influence herbivorous performance and population dynamics. Both silkworm (Bombyx mori L.) and mulberry (Morus alba L.) usually exhibit sexual dimorphism. However, few studies have been conducted on the effect of sex-related silkworm and mulberry pairings on cocoon and silk qualities, which are crucial in sericulture. Here, we compared the differences in cocoon and silk qualities under four feeding combinations (FS-FL: female silkworm fed with leaves from female mulberry trees; MS-FL: male silkworm fed with leaves from female mulberry trees; FS-ML: female silkworm fed with leaves from male mulberry trees; MS-ML: male silkworm fed with leaves from male mulberry trees). The results showed that silkworms exhibited male-biased herbivory with more male mulberry leaves digested. The FS-ML group had higher silk weight and silk ratio of fresh cocoons than the FS-FL group, and the MS-ML group had lower coarse points than the MS-FL group. Compared with groups FS-ML and FS-FL, both MS-FL and MS-ML had smaller cocoons with longer silk lengths and a higher silk ratio of the fresh cocoons. In addition, the Entropy Weight-TOPSIS method showed the cocoon quality rank as FS-ML > FS-FL > MS-FL > MS-ML, whereas silk quality rank was MS-ML > FS-FL > FS-ML > MS-FL. These results indicate that the quality of cocoon and silk is related to the interaction of silkworm and mulberry at the sex level. Furthermore, female silkworms fed with female and male tree leaves have a higher total yield in cocoon production, while male silkworms fed with male tree leaves produced higher silk quality.

Citizen science reveals broad-scale variation of calling activity of the Mediterranean tree frog (Hyla meridionalis) in its westernmost range

Abstract Population monitoring is essential to determine different aspects of the ecology and conservation of the species. In anurans, recording the acoustic activity of choruses allows surveying populations. Therefore, knowing the timing of male calls is fundamental to achieve this goal. Here we monitored calling activity of the Mediterranean tree frog (Hyla meridionalis) at eight localities in southern Iberian Peninsula and western North Africa in the frame of a citizen science program. Subsequently, after summarizing call activity with Non-metric Multidimensional Scaling, we aimed to identify the geographic and environmental variables that associate with the calling activity of frogs. The results of the 258-hour census showed that male tree frogs called mainly from December to July, although the duration and intensity of choruses varied, depending on the elevation and seasonality of the water bodies. Males sang earlier and had more durable call activities at lower elevation sites, which are sites with higher and more stable ambient temperatures. Also, calling activity was lower in sites where water fluctuates more over the annual cycle. Our results provide a first overview of the calling activity of the Mediterranean tree frog over a relatively large set of populations encompassing a wide variety of environmental conditions in its westernmost range of distribution. However, further studies relying on more intensive sampling, likely using automatic recorders, would be desirable to achieve a full understanding of the calling activity of tree frogs in the region.

Climate mediates color morph turnover in a species exhibiting alternative reproductive strategies

Sexual selection is considered the primary driver of morph turnover in many color polymorphic taxa, yet the potential for other factors (like climate) to contribute to polymorphism maintenance and evolution remains unclear. Appreciation for a role of environmental conditions in the maintenance and evolution of color polymorphisms has grown in recent years, generating evidence suggesting that color morphs linked to sexual selection may also diverge in climate sensitivity. Focusing on the three color components contributing to the male tree lizard (Urosaurus ornatus) color morphs, I reveal a marked concordance between patterns of turnover over space and time, with a general affinity of orange- and yellow-colored males to hotter, more variable conditions, and blue colored males to wetter, cooler conditions. An assessment of long-term turnover in the blue color component in response to recent climate change over the past 60 years reinforces these findings. Overall, behavioral asymmetries attributed to sexual selection likely expose competing morphs to divergent environmental conditions in heterogeneous habitats, creating opportunity for natural selection to shape climate sensitivities that also drive turnover in morph color composition. Ultimately, these processes may favor stark asymmetries in morph persistence over the coming decades.

Wind Turbine Noise Behaviorally and Physiologically Changes Male Frogs

Simple SummaryWe analyzed the behavioral–physiological–immunological interconnected process of Japanese tree frogs (Dryophytes japonicus) during their breeding season when exposed to wind turbine noise. Frogs collected from paddy fields with wind power generators exhibited a faster call rate, higher salivary concentrations of corticosterone, and lower innate immunity. However, frogs exposed to the turbine noise for a short period of time only showed faster call rates. An increase in corticosterone was correlated with an increase in call rate and a decrease in immunity. It seems that the need for energy mobilization due to an increase in the call rate leads to a decrease in innate immunity through an increase in corticosterone. The decrease in immunity due to energy tradeoff or physiological response can change disease epidemiology in the population and create new adaptive patterns within these habitats.As the advantages of wind energy as an eco-friendly strategy for power generation continue to be revealed, the number of offshore wind farms also increases worldwide. However, wind turbines can induce behavioral and physiological responses in animals by emitting various types of noises. In this study, we investigated the behavioral, physiological, and immunological responses of male Japanese tree frogs (Dryophytes japonicus) when exposed to wind turbine noise. To determine the effects during the breeding season, frogs were collected from areas with and without wind turbines. Additionally, we exposed the frogs to recorded wind turbine noise at a site without a wind generator for 1 h to 24 h to analyze the short-term effects. Three types of calling patterns (dominant frequency, note duration, and call rate) were analyzed to investigate behavioral responses. Physiological responses were assessed using two steroid hormones assays, namely testosterone and corticosterone detection in the saliva. The immunity of each individual was assessed using a bacterial killing assay. The wind turbine group in the field had a higher call rate and corticosterone levels and lower immunity than the group in the field without turbines present, and all three of these variables were correlated with each other. Conversely, in the noise exposure experiment, a higher call rate was only observed post-exposure compared to pre-exposure. Thus, turbine noise seems to induce decreased immunity in Japanese tree frogs as an increase in energy investment that triggers a behavioral response rather than acting as a sole physiological response that leads to a direct increase in corticosterone. This decreased immunity due to energy tradeoff or physiological response can change the disease epidemiology of the population and create new adaptive patterns in these habitats.

Is the High Proportion of Males in a Population of the Self-Incompatible Fraxinus platypoda (Oleaceae) Indicative of True Androdioecy or Cryptic-Dioecy?

Androdioecy is a rare reproductive system. Fraxinus platypoda, a woody canopy species in Japan’s mountainous riparian zones, is described as a morphologically androdioecious species. In this study, we tried to detect whether F. platypoda is also functionally androdioecious. We analyzed its sexual expression, seed development, pollen morphology and germination ability, pollination systems, and mast flowering behavior. We found that the hermaphrodite trees are andromonoecious, with inflorescences bearing male and hermaphroditic flowers, whereas male individuals had only male flowers. Pollen morphology was identical in male flowers, in hermaphrodite flowers of an andromonoecious individual, and in male flowers of male individuals. Pollen from both types of individuals was capable of germination both ex vivo (on nutrient medium) and in vivo in pollination experiments. However, compared with pollen from andromonoecious trees, pollen from male trees showed a higher germination rate. The self-pollination rate of bagged hermaphroditic flowers was almost zero. The fruit set rate following cross-pollination with male pollen from a male tree was higher than that following natural pollination, whereas the rate with hermaphroditic pollen was the same. The flowering and fruiting of F. platypoda have fluctuated over 17 years; the flowering of the two types of sexual individuals exhibited clear synchronization during this period. The frequency of male individuals within the populations is 50%. The maintenance of such a proportion of males in populations of the self-incompatible F. platypoda is either indicative of a true androdioecious species with a diallelic self-incompatibility system or a cryptic-dioecious species. This alternative is discussed here.

Differentially Expressed Genes Analysis of Brown Adipose Tissue During Cold Acclimation in Male Tree Shrews (Tupaia belangeri) based on RNA-Seq

Differentially Expressed Genes Analysis of Brown Adipose Tissue During Cold Acclimation in Male Tree Shrews (Tupaia belangeri) based on RNA-Seq

Recruitment facilitation in expanding forests of Mediterranean juniper is sex-biased

Despite noticeable concern about the deforestation rate worldwide, the forest surface in Europe has considerably expanded over the past centuries as a consequence of the rural exodus and abandonment of agrarian practices. Tree recruitment associated with forest regrowth is a multi-stage process influenced by several biotic and abiotic factors. Yet, it is uncertain whether their influence on recruitment patterns and dynamics varies along a gradient of forest expansion. Similarly, for dioceious species, the influence of tree sex in recruitment is not entirely understood. Here, we aim to elucidate what drives Spanish juniper recruitment in expanding forests. Specifically, we hypothesized that facilitation by conspecifics and heterospecific woody species would occur at the expanding front, where environmental conditions are harsher and that recruitment would be preferably associated to female trees because of the likelihood of mature cones produced by them germinating in the nearby area. The study was conducted in Mediterranean forests of Juniperus thurifera in central Spain. A total of 17 plots were delimited along a gradient of forest expansion including three stages: i) old forests, ii) an intermediate zone and iii) novel forests at the expanding front. Within each plot all J. thurifera individuals (saplings and adults) were mapped. We also recorded bio-volumetric characteristics and tree sex for all adult trees and estimated the percentage of cover of heterospecific woody species within the area of influence of each adult individual. We analysed the spatial pattern of J. thurifera individuals for each stand (plot). Using a novel spatial approach, we evaluated how conspecific (female and male tree sizes) and heterospecific (woody cover) vegetation influenced sapling density along a forest expansion gradient. We also studied the effects of the stage of the forest expansion gradient and the sex of adult trees on the spatial association between adults and saplings. Our results showed that sapling recruitment was negatively influenced by conspecific adult size along the whole gradient, while the effect of heterospecific woody vegetation was always positive. Conspecific facilitation of recruitment in J. thurifera forests occurred at their expanding front where saplings were associated to male adult trees. Despite having been overlooked in conservation policies, recently colonised areas in extreme environments are key targets to implement management measures aimed at achieving forest restoration, which aligns with the Aichi targets and the biodiversity policies of the European Union.

Body temperature is a repeatable trait in a free-ranging passerine bird.

Body temperature (Tb) affects animal function through its influence on rates of biochemical and biophysical reactions, the molecular structures of proteins and tissues, and, ultimately, organismal performance. Despite its importance in driving physiological processes, there are few data on how much variation in Tb exists within populations of organisms, and whether this variation consistently differs among individuals over time (i.e. repeatability of a trait). Here, using thermal radio-frequency identification implants, we quantified the repeatability of Tb, both in the context of a fixed average environment (∼21°C) and across ambient temperatures (6-31°C), in a free-living population of tree swallows (Tachycineta bicolor, n=16). By experimentally trimming the ventral plumage of a subset of female swallows (n=8), we also asked whether the repeatability of Tb is influenced by the capacity to dissipate body heat. We found that both female and male tree swallow Tb was repeatable at 21°C (R=0.89-92), but female Tb was less repeatable than male Tb across ambient temperature (Rfemale=0.10, Rmale=0.58), which may be due to differences in parental investment. Trimmed birds had on average lower Tb than control birds (by ∼0.5°C), but the repeatability of female Tb did not differ as a function of heat dissipation capacity. This suggests that trimmed individuals adjusted their Tb to account for the effects of heat loss on Tb. Our study provides a first critical step toward understanding whether Tb is responsive to natural selection, and for predicting how animal populations will respond to climatic warming.