The lack of recovery of Chinook salmon (Oncorhynchus tshawytscha) in the Pacific Northwest has been blamed in part on predation by pinnipeds, particularly the harbor seal (Phoca vitulina). Previous work at a limited number of locations has shown that male seal diet contains more salmon than that of female seals and that sex ratios at haul-out sites differ spatiotemporally. This intrapopulation variation in predation may result in greater effects on salmon than suggested by models assuming equal spatial distribution and diet proportion. To address the generality of these patterns, we examined the sex ratios and diet of male and female harbor seals from 13 haul-out sites in the inland waters of Washington State and the province of British Columbia during 2012-2018. DNA metabarcoding was conducted to determine prey species proportions of individual scat samples. The sex of harbor seals was then determined from each scat matrix sample with the use of quantitative polymerase chain reaction (qPCR). We analyzed 2405 harbor seal scat samples using generalized linear mixed models (GLMMs) to examine the factors influencing harbor seal sex ratio at haul-out sites and permutational multivariate analysis of variance (PERMANOVA) to examine the influence of sex and haul-out site on harbor seal diet composition. We found that the overall sex ratio was 1:1.02 (female:male) with notable spatiotemporal variation. Salmoniformes were about 2.6 times more abundant in the diet of males than in the diet of females, and Chinook salmon comprised ca. three times more of the average male harbor seal\'s diet than the average female\'s diet. Based on site-specific sex ratios and diet data, we identified three haul-out sites where Chinook salmon appear to be under high predation pressure by male harbor seals: Cowichan Bay, Cutts Area, and Fraser River. Our study indicates that combining sex-specific pinniped diet data with the sex ratio of haul-out sites can help identify priority sites of conservation concern.

Ginkgo biloba L. is a rare dioecious species that is valued for its diverse applications and is cultivated globally. This study aimed to develop a rapid and effective method for determining the sex of a Ginkgo biloba. Green and yellow leaves representing annual growth stages were scanned with a hyperspectral imager, and classification models for RGB images, spectral features, and a fusion of spectral and image features were established. Initially, a ResNet101 model classified the RGB dataset using the proportional scaling-background expansion preprocessing method, achieving an accuracy of 90.27%. Further, machine learning algorithms like support vector machine (SVM), linear discriminant analysis (LDA), and subspace discriminant analysis (SDA) were applied. Optimal results were achieved with SVM and SDA in the green leaf stage and LDA in the yellow leaf stage, with prediction accuracies of 87.35% and 98.85%, respectively. To fully utilize the optimal model, a two-stage Period-Predetermined (PP) method was proposed, and a fusion dataset was built using the spectral and image features. The overall accuracy for the prediction set was as high as 96.30%. This is the first study to establish a standard technique framework for Ginkgo sex classification using hyperspectral imaging, offering an efficient tool for industrial and ecological applications and the potential for classifying other dioecious plants.

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.

1. Male and female Chukar partridges are difficult to differentiate based on their morphology or by the Chromobox-Helicase-DNA binding (CHD) during early growth.2. The current study developed a novel, simple, low-cost and rapid sexing protocol for Chukar partridges based on the newly defined sexing gene ubiquitin-associated protein 2 (UBAP2).3. The length of polymorphism between UBAP2-W and UBAP2-Z homologous genes allows for easy sex discrimination in this species. Molecular sexing analysis was based on the simultaneous amplification of both genes, resulting in two distinct amplicons (947 bp and 535 bp) in heterogametic females and only a single band (535 bp) in homogametic males, which is easy to detect with agarose gel electrophoresis.4. This technique is simple and convenient for genetic sex determination in Chukar partridges.

California halibut (Paralichthys californicus) is a candidate species for aquaculture and stock enhancement. These applications rely on sex control, either to maximize the production of faster growing females or to match sex ratios in the wild. Other paralichthids exhibit temperature-dependent sex determination (TSD), but the presence and pattern of TSD is not well defined in California halibut. Juvenile California halibut were cultured at three distinct temperatures (15°C, 19°C, and 23°C) through the developmental period presumed to be thermosensitive based on findings from congeners. Sex ratios were quantified in each treatment using phenotypic sex identification techniques applied early (molecular biomarkers; 51-100 mm total length [TL]) and late (visual examination of the gonads; ≥100 mm TL) in the juvenile phase. Both techniques indicated similar sex determination trends at each temperature, with overall sex ratios assessed as 49.9% male at 15°C, 74.5% male at 19°C, and 98.2% male at 23°C. Growth rates were highest at 23°C and lowest at 15°C, with intrinsically fast- and slow-growing individuals at all temperatures. At 15°C and 19°C, females comprised a higher proportion among the fast growers than they did among the slow growers. These data show that California halibut exhibit TSD, with temperatures of 19°C and 23°C masculinizing fish while 15°C appears to produce a 1:1 sex ratio. This study will help optimize sex ratios and growth in hatcheries through thermal manipulation. Furthermore, the developed biomolecular tools and identified temperature thresholds will be important in future work to understand the influence of global warming on wild population demographics.

Sex identification of ducklings is a critical step in the poultry farming industry, and accurate sex identification is beneficial for precise breeding and cost savings. In this study, a method for identifying the sex of ducklings based on acoustic signals was proposed. In the first step, duckling vocalizations were collected and an improved spectral subtraction method and high-pass filtering were applied to reduce the influence of noise. Then, duckling vocalizations were automatically detected by using a double-threshold endpoint detection method with 3 parameters: short-time energy (STE), short-time zero-crossing rate (ZCR), and duration (D). Following the extraction of Mel-Spectrogram features from duckling vocalizations, an improved Res2Net deep learning algorithm was used for sex classification. This algorithm was introduced with the Squeeze-and-Excitation (SE) attention mechanism and Ghost module to improve the bottleneck of Res2Net, thereby improving the model accuracy and reducing the number of parameters. The ablative experimental results showed that the introduction of the SE attention mechanism improved the model accuracy by 2.01%, while the Ghost module reduced the number of model parameters by 7.26M and the FLOPs by 0.85G. Moreover, this algorithm was compared with 5 state-of-the-art (SOTA) algorithms, and the results showed that the proposed algorithm has the best cost-effectiveness, with accuracy, recall, specificity, number of parameters, and FLOPs of 94.80, 94.92, 94.69, 18.91M, and 3.46G, respectively. After that, the vocalization detection score and the average confidence strategy were used to predict the sex of individual ducklings, and the accuracy of the proposed model reached 96.67%. In conclusion, the method proposed in this study can effectively detect the sex of ducklings and serve as a reference for automated sex identification of ducklings.

The sex of dioecious plants is mainly determined by genetic factors, but it can also be converted by environmental cues such as exogenous phytohormones. Gibberellic acids (GAs) are well-known inducers of flowering and sexual development, yet the pathway of gibberellin-induced sex conversion in dioecious spinach (Spinacia oleracea L.) remains elusive. Based on sex detection before and after GA3 application using T11A and SSR19 molecular markers, we confirmed and elevated the masculinization effect of GA on a single female plant through exogenous applications of GA3, showing complete conversion and functional stamens. Silencing of GIBBERELLIC ACID INSENSITIVE (SpGAI), a single DELLA family protein that is a central GA signaling repressor, results in similar masculinization. We also show that SpGAI can physically interact with the spinach KNOX transcription factor SHOOT MERISTEMLESS (SpSTM), which is a homolog of the flower meristem identity regulator STM in Arabidopsis. The silencing of SpSTM also masculinized female flowers in spinach. Furthermore, SpSTM could directly bind the intron of SpPI to repress SpPI expression in developing female flowers. Overall, our results suggest that GA induces a female masculinization process through the SpGAI-SpSTM-SpPI regulatory module in spinach. These insights may help to clarify the molecular mechanism underlying the sex conversion system in dioecious plants while also elucidating the physiological basis for the generation of unisexual flowers so as to establish dioecy in plants.

The ability to sex individuals is an important component of many behavioural and ecological investigations and provides information for demographic models used in conservation and species management. However, many birds are difficult to sex using morphological characters or traditional molecular sexing methods. In this study, we developed probabilistic models for sexing birds using quantitative PCR (qPCR) data. First, we quantified distributions of gene copy numbers at a set of six sex-linked genes, including the sex-determining gene DMRT1, for individuals across 17 species and seven orders of birds (n = 150). Using these data, we built predictive logistic models for sex identification and tested their performance with independent samples from 51 species and 13 orders (n = 209). Models using the two loci most highly correlated with sex had greater accuracy than models using the full set of sex-linked loci, across all taxonomic levels of analysis. Sex identification was highly accurate when individuals to be assigned were of species used in model building. Our analytical approach was widely applicable across diverse neognath bird lineages spanning millions of years of evolutionary divergence. Unlike previous methods, our probabilistic framework incorporates uncertainty around qPCR measurements as well as biological variation within species into decision-making rules. We anticipate that this method will be useful for sexing birds, including those of high conservation concern and/or subsistence value, that have proven difficult to sex using traditional approaches. Additionally, the general analytical framework presented in this paper may also be applicable to other organisms with sex chromosomes.

Accurate gender identification is crucial for the study of bird reproduction and evolution. The current study aimed to explore and evaluate the effectiveness of a noninvasive method for gender identification in Yangzhou geese. In this experiment, 600 goose eggs were collected. Hair root tissues were used for PCR amplification, molecular sequencing, and anal inversion for early sex recognition in goslings. According to the DNA amplification results for the feather pulp tissue of 2-wk-old geese, bands appeared at 436 bp (CHD1-Z) and 330 bp (CHD1-W) upon gel electrophoresis. This method considered the base of goose feathers to accelerate the process of gender recognition. By examining the sex of anatomized poultry for verification, the accuracy rate of PCR gel electrophoresis and molecular sequencing sex identification was 100%, whereas the average accuracy rate of anal inversion was 97.41%. In the comparison of feather growth trends at 0 to 18 wk of age, the feather root weight (FRW), feather root length (FRL), feather branch length (FBL), and feather shaft diameter (FSD) of Yangzhou goose of the same age were not significantly different between males and females (P > 0.05). At 6 wk of age, the FRW, FRL, and FSD in males and FRL in females increased rapidly; their growth increased by 84.43, 67.58, 45.10, and 69.42%, respectively. At 10 wk of age, the male FRL, male FBL, and female FBL increased by 37.31, 34.81, and 21.72, respectively. The Boltzmann model was found to be the best-fitting model for the feathers of male Yangzhou geese. Early sex identification based on feather growth trends between the sexes is not feasible. This study provides a convenient and reliable technical means for early sex identification of waterfowl and serves as an ecological strategy for protecting the reproduction of poultry populations.

BACKGROUND: Morphological and morphometric features of the teeth are of interest to various clinical and academic dental and medical fields including prosthodontics, orthodontics, anatomy and anthropology, pathology, archeology, and forensic dentistry. These have been more or less researched in the case of the permanent dentition. However when it comes to the primary dentition, the literature is scarce and controversial. No study worldwide exists on the cutoff points (thresholds) for sex identification; no study exists on metric or nonmetric traits of deciduous teeth in Iranians. Hence, the aim of the study was to assess both the metric and nonmetric traits of primary molars, as well as their cut-off points for sex identification.
METHODS: In this epidemiological cross-sectional study, pretreatment casts of 110 children (51 boys and 59 girls) aged 6 to 12 years were collected. Maxillary and mandibular first and second primary molars were evaluated regarding their metric traits (mesiodistal and buccolingual widths) and 9 nonmetric traits (Accessory cusp on the upper D, Accessory cusp on the lower D, Fifth cusp on the upper E, Carabelli\'s cusp on the upper E, Protostylid on the lower E, Fifth cusp on the lower E, Sixth cusp on the lower E, Tuberculum intermedium [metaconulid] on the lower E, and Deflecting wrinkle on the lower E). ROC curves were used to identify cut-off points for sex determination as well as the usefulness of metric measurements for this purpose. Data were analyzed using independent-samples and paired-samples t-tests, McNemar, Fisher, and chi-square tests, plus Pearson and Spearman correlation coefficients (α = 0.05).
RESULTS: All the primary molars\' coronal dimensions (both mesiodistal and buccolingual) were extremely useful for sex identification (ROC curves, all P values ≤ 0.0000099). Especially, the mandibular primary molars (areas under ROC curves [AUCs] between 85.6 and 90.4%, P values ≤ 0.0000006) were more useful than the maxillary ones (AUCs between 80.4 and 83.1%, P values ≤ 0. 0000099). In the mandible, the first primary molar (maximum AUC = 90.4%) was better than the second molar (maximum AUC = 86.0%). The optimum thresholds for sex determination were reported. Sex dimorphism was significant in buccolingual and mesiodistal crown widths of all the primary molars (all P values ≤ 0.000132), but it was seen only in the case of 2 nonmetric traits: Deflecting wrinkle (P = 0.001) and Tuberculum intermedium (metaconulid, P = 0.029) on the lower Es, taking into account the unilateral and bilateral cases. The occurrence of nonmetric traits was symmetrical between the right and left sides (all P values ≥ 0.250). All mesiodistal and two buccolingual molar measurements were as well symmetrical (P > 0.1); however, two buccolingual measurements were asymmetrical: in the case of the maxillary E (P = 0.0002) and mandibular D (P = 0.019). There were three weak-to-moderate correlations between the nonmetric traits of the mandibular second molars (Spearman correlations between 22.7 and 37.5%, P values ≤ 0.045). Up to 6 concurrent nonmetric traits were observed in the sample, with 53.6% of the sample showing at least 2 concurrent nonmetric traits at the same time, without any sex dimorphism (P = 0.658).
CONCLUSIONS: Sex dimorphism exists considerably in primary molars\' sizes, but it is not as prevalent in their nonmetric traits or abnormalities. Primary molars\' crown sizes are useful for sex identification; we calculated optimum cut-off points for this purpose, for the first time.