Image-based morphometric analysis reveals sexual dimorphism in the threatened yellow-spotted mountain newt (Neurergus derjugini): applications of deep learning and automated pattern recognition

The yellow-spotted mountain newt (Neurergus derjugini), an endangered amphibian endemic to the Zagros Mountains, faces critical threats from habitat loss and climate change. Effective conservation requires reliable population monitoring, yet traditional marking methods are invasive and impractical. This study presents a non-invasive, image-based approach combining geometric computer vision and deep learning for individual identification and population estimation. We captured 549 adult N. derjugini in their natural habitat, photographing dorsal patterns under standardized conditions. A geometric pipeline (HSV thresholding, morphological operations) extracted yellow spot features (area, circularity, count), achieving 93% detection accuracy. Three convolutional neural networks (CNNs)-DenseNet121, EfficientNetB0, and InceptionV3-were fine-tuned for phenotypic classification, with DenseNet121 attaining the highest accuracy (99.11%) and AUC (0.98). Region-specific analysis showed optimal performance when combining head and trunk patterns (96.32% accuracy). A mark-recapture framework, applied to two sampling sessions (n = 332 and 217 individuals), identified 65 recaptures, yielding a Lincoln-Petersen population estimate of 1108 individuals. Our results demonstrate that deep learning outperforms traditional methods in robustness and scalability, particularly under variable field conditions. This study advances amphibian conservation by providing a rapid, ethical, and scalable tool for monitoring endangered species. Future directions include expanding datasets for temporal stability validation and deploying mobile applications for real-time field use. By integrating AI with ecological research, this work highlights the transformative potential of automated identification in biodiversity conservation.

Sexual Selection and Variance in Reproductive Success

In most animals, females are larger than males. Paradoxically, sexual size dimorphism is biased towards males in most mammalian species. An accepted explanation is that sexual dimorphism in mammals evolved by intramale sexual selection. I tested this hypothesis in primates, by relating sexual size dimorphism to seven proxies of sexual selection intensity: operational sex ratio, mating system, intermale competition, group sex ratio, group size, maximum mating percentage (percentage of observed copulations involving the most successful male), and total paternity (a genetic estimate of the percentage of young sired by the most successful male). I fitted phylogenetic generalised least squares models using sexual size dimorphism as the dependent variable and each of the seven measures of intensity of sexual selection as independent variables. I conducted this comparative analysis with data from 50 extant species of primates, including Homo sapiens, Pan troglodytes, and Gorilla spp. Sexual dimorphism was positively related to the four measures of female monopolisation (operational sex ratio, mating system, intermale competition, and group sex ratio) and in some cases to group size, but was not associated with maximum mating percentage or total paternity. Additional regression analyses indicated that maximum mating percentage and total paternity were negatively associated with group size. These results are predicted by reproductive skew theory: in large groups, males can lose control of the sexual behaviour of the other members of the group or can concede reproductive opportunities to others. The results are also consistent with the evolution of sexual size dimorphism before polygyny, due to the effects of natural, rather than sexual, selection. In birds, the study of molecular paternity showed that variance in male reproductive success is much higher than expected by behaviour. In mammals, recent studies have begun to show the opposite trend, i.e. that intensity of sexual selection is lower than expected by polygyny. Results of this comparative analysis of sexual size dimorphism and sexual selection intensity in primates suggest that the use of intramale sexual selection theory to explain the evolution of polygyny and sexual dimorphism in mammals should be reviewed, and that natural selection should be considered alongside sexual selection as an evolutionary driver of sexual size dimorphism and polygyny in mammals.

Objective The automation of brachytherapy is the direction of future development. This article retrospectively studied the application of deep learning in brachytherapy of cervical cancer and clarified the status quo of development. Method This survey reviewed the application of machine learning and deep learning in brachytherapy for cervical cancer in the past 10 years. The survey retrieved and reviewed electronic journal articles in scientific databases such as Google Scholar and IEEE. The three sets of keywords used 1) deep learning, brachytherapy, 2) machine learning, brachytherapy, 3) automation, brachytherapy. Results Through research on the application of deep learning in brachytherapy, it is found that the U-net model is basically based on convolutional neural networks or some attention mechanisms are added to it, and it is applied to brachytherapy of prostate or cervical cancer. The automatic segmentation and reconstruction of the mid-source applicator (interpolation needle), target area delineation, optimization in the treatment planning system and dose calculation have achieved good results, proving that deep learning can be applied to the clinical treatment of brachytherapy. Conclusion The research on the application of deep learning in brachytherapy confirmed that deep learning can effectively promote the development of brachytherapy.

Assessing the long-term macroevolutionary consequences of sexual selection has been hampered by the difficulty of studying this process in the fossil record. Cytheroid ostracodes offer an excellent system to explore sexual selection in the fossil record because their readily fossilized carapaces are sexually dimorphic. Specifically, males are relatively more elongate than females in this superfamily. This sexual shape difference is thought to arise so that males carapaces can accommodate their very large copulatory apparatus, which can account for up to one-third of body volume. Here we test this widely held explanation for sexual dimorphism in cytheroid ostracodes by correlating investment in male genitalia, a trait in which sexual selection is seen as the main evolutionary driver, with sexual dimorphism of carapace in the genus Cyprideis. We analyzed specimens collected in the field (C. salebrosa, USA; C. torosa, UK) and from collections of the National Museum of Natural History, Washington, DC (C. mexicana). We digitized valve outlines in lateral view to obtain measures of size (valve area) and shape (elongation, measured as length to height ratio), and obtained several dimensions from two components of the hemipenis: the muscular basal capsule, which functions as a sperm pump, and the section that includes the intromittent organ (terminal extension). In addition to the assessment of this primary sexual trait, we also quantified two dimensions of the male secondary sexual trait—where the transformed right walking leg functions as a clasping organ during mating. We also measured linear dimensions from four limbs as indicators of overall (soft-part) body size, and assessed allometry of the soft anatomy. We observed significant correlations in males between valve size, but not elongation, and distinct structural parts of the hemipenis, even after accounting for their shared correlation with overall body size. We also found weak but significant positive correlation between valve elongation and the degree of sexual dimorphism of the walking leg, but only in C. torosa. The correlation between the hemipenis parts, especially basal capsule size and male valve size dimorphism suggests that sexual selection on sperm size, quantity, and/or efficiency of transfer may drive sexual size dimorphism in these species, although we cannot exclude other aspects of sexual and natural selection.

Sexual size dimorphism might be influenced by environmental constraints on sexual selection or by intraspecific competition between males and females. We studied bobcats (Lynx rufus) in collections of museum specimens from western North America to examine these hypotheses. Structural body size was estimated from several measurements of the skull, ln-transformed and indexed through principal components analysis. Sexual dimorphism in body size was estimated from the difference in size index of males and females, and compared to geographic and climatic variables associated with biotic provinces (ecoregions). Of several climatic variables that were associated with bobcat body size, only seasonality of climate was associated with sexual dimorphism. Sexual size dimorphism, longitude, elevation, and seasonality were intercorrelated. As longitude decreased (moving inland from west-coastal ecoregions), sexual dimorphism decreased with the increased elevation and seasonality of continental climates of the Rocky Mountains. We suggest that increased seasonality and the need for fasting endurance by females may place constraints on the degree of sexual dimorphism in bobcats. Sexual dimorphism of body size and sexual size dimorphism of trophic structures (teeth) exhibited a strong positive association over geography, thus indirectly supporting the hypothesis that intrasexual competition for prey could account for the geographic variation in sexual size dimorphism. Thus, both environmental constraints on sexual selection of body size and intersexual competition were supported as possible explanations of the degree of sexual size dimorphism that occurs in populations of bobcats.

Sexual size dimorphism is assumed to be adaptive and is expected to evolve in response to a difference in the net selection pressures on the sexes. Although a demonstration of sexual selection is neither necessary nor sufficient to explain the evolution of sexual size dimorphism, sexual selection is generally assumed to be a major evolutionary force. If contemporary sexual selection is important in the evolution and maintenance of sexual size dimorphism then we expect to see concordance between patterns of sexual selection and patterns of sexual dimorphism. We examined sexual selection in the wild, acting on male body size, and components of body size, in the waterstrider Aquarius remigis, as part of a long term study examining net selection pressures on the two sexes in this species. Selection was estimated on both a daily and annual basis. Since our measure of fitness (mating success) was behavioral, we estimated reliabilities to determine if males perform consistently. Reliabilities were measured as ϰ statistics and range from fair to perfect agreement with substantial agreement overall. We found significant univariate sexual selection favoring larger total length in the first year of our study but not in the second. Multivariate analysis of components of body size revealed that sexual selection for larger males was not acting directly on total length but on genital length. Sexual selection for larger male body size was opposed by direct selection favoring smaller midfemoral lengths. While males of this species are smaller than females, they have longer genital segments and wider forefemora. Patterns of contemporary sexual selection and sexual size dimorphism agree only for genital length. For total length, and all other components of body size examined, contemporary sexual selection was either nonsignificant or opposed the pattern of size dimporhism. Thus, while the net pressures of contemporary selection for the species may still act to maintain sexual size dimorphism, sexual selection alone does not.

Mate choice based on body size similarity in sexually dimorphic populations causes strong sexual selection

Evolutionary biologists have long focused on the patterns and causes of sexual size dimorphism (SSD). While female-biased SSD is common among ectotherms, a few lineages predominately exhibit male-biased SSD. One example is the clade of desmognathans, a monophyletic group of two genera within the Plethodontinae of the lungless salamander family Plethodontidae. Members of these two genera have a unique pattern of SSD: males mature earlier and at smaller sizes than females but reach greater maximum sizes. We used comparative phylogenetic methods to test whether SSD in these salamanders is the result of sexual selection on males. Spatial evolutionary and ecological vicariance analysis indicated a significant divergence in SSD associated with the phylogenetic origin of the desmognathans. Phylogenetic least-squares regression across the two most speciose genera of the subfamily determined a significant relationship between SSD and adult sex ratio. While male desmognathans are not sexually dimorphic in head size, they have a unique head morphology that causes their heads to grow more rapidly as their body size increases as compared with the heads of other salamanders. This pattern of allometric growth combines with a powerful bite force and enlarged premaxillary teeth to create formidable weaponry that probably is more responsive to sexual selection.

Sexual selection in amphibians is often based on size and color dimorphism, and most studies have used anurans. Sexual selection in urodeles remains understudied. Dorsal coloration of Fire Salamanders (Salamandra salamandra) has traditionally been interpreted as an aposematic signal. However, recent findings suggest that dorsal pigmentation may also exhibit sexual dimorphism and be important in mate choice. Here, we investigated a large population of Salamandra salamandra terrestris to explore relationships among sex, dorsal spot number, and yellow surface area. We found significant sexual dimorphism: females displayed a higher number of dorsal spots whereas males exhibited greater overall yellow surface area coverage. Moreover, spot number was negatively correlated with yellow surface area in both sexes, indicating a trade-off between spot fragmentation and continuous yellow patches. These results expand upon previous research by contributing a much larger data set and jointly analyzing spot number and yellow surface area. They suggest that pigmentation in Fire Salamanders could function not only as a protective signal against predators but also as a sexually selected trait. The possible role of dorsal coloration in mate choice warrants further investigation.

In a model group of giant reptiles, we explored the allometric relationships between male and female body size and compared the effects of sexual and fecundity selection, as well as some proximate causes, on macroevolutionary patterns of sexual size dimorphism (SSD). Monitor lizards are a morphologically homogeneous group that has been affected by extreme changes in body size during their evolutionary history, resulting in 14-fold differences among the body sizes of recent species. Here, we analysed data concerning the maximum and/or mean male and female snout—vent lengths in 42 species of monitor lizard from literary sources and supplemented these data with measurements made in zoos. There was a wide scale of SSD from nearly monomorphic species belonging mostly to the subgenus Odatria and Prasinus group of the Euprepriosaurus to apparently male-larger taxa. The variable best explaining SSD was the body size itself; the larger the species, the higher the SSD. This pattern agrees with the currently discussed Rensch's rule, claiming that the relationship between male and female body size is hyperallometric, i.e. the allometric exponent of this relationship exceeds unity and thus SSD increases with body size in the case of male-larger taxa. All our estimates of the reduced major axis regression slopes of this relationship ranged from 1.132 to 1.155. These estimates are significantly higher than unity, and thus unequivocally corroborate the validity of Rensch's rule in this reptilian group. In spite of our expectation that the variation in SSD can be alternatively explained by variables reflecting the strength of sexual selection (presence of male combat), fecundity selection (e.g. clutch size and mass) and/or proximate ecological factors (habitat type), none of these variables had consistent effects on SSD, especially when the data were adjusted to phylogenetic dependence and/or body size.

-The mortality of territorial male Red-winged Blackbirds (Agelaius phoeniceus) was determined in a banded population during the breeding seasons of 1973-1978. I used these data to test the hypothesis that sexual selection for characteristics that are advantageous in territory defense or mate acquisition, or both, occurs at the expense of survivorship. Observations of males that returned to the study area to reestablish territories, and of the tenures of these males on their territories, enabled me to partition annual mortality into components that estimate mortality during the and breeding seasons. The mean annual mortality of territorial male Red-wings was 52%, with 29% mortality occurring during the nonbreeding season (1 June to approximately 1 March) and 22% mortality occurring during the breeding season before 1 June. The effect of body size on survivorship was investigated by correlating male wing lengths measured in the third year of life with their ages at death. The correlation between wing length and survivorship was negative (-0.438) and statistically significant (one-tailed P < 0.05). I conclude that mortality during the breeding season is a potentially important selective force in this species, and that sexual selection may have occurred at the expense of survivorship. Sexual selection for large males appears to be opposed by survival selection for small males. Received 13 January 1986, accepted 15 July 1986. DARWIN (1859, 1871) viewed natural and sexual selection as separate but complementary mechanisms of evolution. According to Darwin, natural selection favors adaptations that increase survival, while sexual selection favors adaptations that increase the ability to acquire mates but decrease survival. In contrast, contemporary evolutionary biologists consider both selection for increased survival (survival selection) and selection for increased mating ability (sexual selection) as components of natural selection (see Mayr 1972, Selander 1972). Sexual selection, however, is still thought to occur at the cost of decreased survival (e.g. Selander 1965, Searcy 1979, O'Donald 1980, Lande 1981, Searcy and Yasukawa 1981, Kirkpatrick 1982). Thus, when sexual selection produces sexual dimorphism, the larger and more conspicuous sex is presumed to pay a cost in higher mortality (see Andersson 1982, Searcy and Yasukawa 1983, Payne 1984). Survival selection therefore would act to limit the effects of sexual selection because it would favor smaller, less conspicuous individuals of the sexually selected sex. Although the opposition of sexual and survival selection has been presumed since Darwin (1859), there have been relatively few attempts to document the reduced survival that should accompany sexual selection. The Red-winged Blackbird (Agelaius phoeniceus) is a species in which sexual dimorphism is thought to be the product of sexual selection (see Searcy and Yasukawa 1983). Male Redwings are larger and more conspicuous than are females (Nero 1956a, b; Orians and Christman 1968), and sexual selection is a potentially important evolutionary force because the variance in mating success is high (Payne 1979). However, although sexual selection is thought to act more strongly on male than on female Red-winged Blackbirds (Payne 1979), male and female Red-wing survivorship is virtually identical (Fankhauser 1971, Searcy and Yasukawa 1981). Thus, there is no evidence that males pay a cost in increased mortality. Furthermore, there is little evidence that larger male Red-winged Blackbirds suffer higher mortality than do smaller males (Searcy 1979, Johnson et al. 1980). These observations are inconsistent with the generally accepted view that sexual selection is primarily responsible for the sexual dimorphism in size, plumage, and behavior in Red-winged Blackbirds (see Searcy and Yasukawa 1983). I tested the hypothesis that sexual selection has favored characteristics that enhance a male's ability to acquire a territory or mates, but at the expense of his survival (Selander 1965, Searcy 56 The Auk 104: 56-62. January 1987 This content downloaded from 207.46.13.105 on Wed, 25 May 2016 05:23:12 UTC All use subject to http://about.jstor.org/terms January 1987] Mortality of Male Red-winged Blackbirds 57 1979). This sexual-selection hypothesis predicts that the mortality of males during the breeding season should represent a considerable portion of annual mortality because males pay a cost that results from their conspicuous and energetically expensive attempts to defend their territories and attract mates. I tested this prediction by partitioning the annual mortality of male Red-winged Blackbirds into components that estimate mortality in the breeding and seasons. The hypothesis also predicts that counter-balancing survival selection will favor small males. I tested this prediction by examining the relationship between size and survival of male Red-winged Blackbirds.

The causal relationship between sexual selection and sexual size dimorphism in marine gastropods

We investigated sexual dimorphism of the Kurdistan newt, Neurergus microspilotus (Nesterov, 1916), using a sample of 20 males and 12 females originated from the north-western part of Kermanshah Province, western Iran. Ten morphometric characters were measured. Almost all measured characteristics were significantly different between males and females.

Rensch's rule (RR) states that sexual size dimorphism (SSD) increases with body size in male-biased SSD taxa, and decreases with body size in female-biased SSD taxa. This pattern implies that males change body size faster than females through evolutionary time, and that sexual selection might be the main evolutionary force behind this pattern. Phenotypic plasticity has been proposed as a proximate potential mechanism of RR by affecting body growth in a differential manner in males and females. In this dissertation I studied the role of phenotypic plasticity as a mechanism affecting sexual size and shape dimorphism in two turtle species exhibiting contrasting SSD: Chelydra serpentina that exhibits male-biased SSD, and Podocnemis expansa that exhibits female-biased SSD. I found that males of the male-biased SSD species exhibited increased growth plasticity relative to females, thus supporting the differential plasticity hypothesis as a mechanism that facilitates body size enhancement and thus the evolution of SSD in a manner consistent with RR. Whether differential plasticity enhances body size of the larger sex in general, or of males in particular, was addressed in the second experiment. In this second experiment I found no differences in growth plasticity between males and females, thus failing to support the differential plasticity hypothesis in the female-biased SSD species. The combined evidence from both studies suggest that differential plasticity is neither specific to males nor to the larger sex, but instead that it is species-specific. Whether turtles follow Rensch's rule or not was tested in a third analysis by correlating body size of males and females of 138 turtle species in a phylogenetic context and at multiple taxonomic levels. I found no support for Rensch's rule in turtles at the order level and in most families. Instead, results suggest that SSD has evolved independently of the species average body size in those clades. I also found that the family Chelydridae and one subclade within the Testudinidae family follow Rensch's rule, while the Podocnemididae family follows a pattern exactly opposite to Rensch's rule. These results are in agreement with the result of the common garden experiments. Namely, I found support for sex-specific growth plasticity as a mechanism facilitating RR in C. serpentina, a species belonging to the family Chelydridae that follows RR. Furthermore, no support for sex-specific growth plasticity as a mechanism facilitating RR was detected in P. expansa, a species belonging to the family Podocnemididae that does not follow RR. Further research is warranted to test the role of the sex-specific growth plasticity in female-biased SSD species belonging to clades that follow Rensch's rule. Likewise, similar studies should be conducted in male-biased SSD species belonging to clades that do not follow Rensch's rule.