Baby snakes: maternal investment and neonate sexing in smooth snakes

Sex ratios affect population dynamics and individual fitness, and changing sex ratios can be indicative of shifts in sex‐specific survival at different life stages. While climate and landscape changes alter sex ratios of wild bird populations, long‐term, landscape scale assessments of sex ratios are rare. Further, little work has been done to understand changes in sex ratios in avian communities. In this manuscript, we analyze long‐term (1961–2015) data on five species of ducks across five broad climatic regions of the United States to estimate the effects of drought and long‐term trends on the proportion of juvenile females captured at banding. As waterfowl have a 1:1 sex ratio at hatch, we interpret changes in sex ratios of captured juveniles as changes in sex‐specific survival rates during early life. Seven of 12 species‐region pairs exhibited evidence for long‐term trends in the proportion of juvenile females at banding. The proportion of juvenile females at banding increased for duck populations in the western United States and typically declined for duck populations in the eastern United States. We only observed evidence for an effect of drought in two of the 12 species‐region pairs, where the proportion of females declined during drought. As changes to North American landscapes and climate continue and intensify, we expect continued changes in sex‐specific juvenile survival rates. More broadly, we encourage further research examining the mechanisms underlying long‐term trends in juvenile sex ratios in avian communities.

Gestation length, birth weight and offspring gender ratio of in vitro-produced Gyr ( Bos indicus) cattle embryos

Since there is a tradeoff between prolongedformal education and early reproduction, education canbe construed as a long-term reproductive tactic. Thisreproductive strategies approach was tested by looking at relationships between sociosexuality (SOI)and parental investment (parental income, number ofsiblings, parental divorce, number of step siblings,birth intervals, birth order, closeness to parents) and GPA of 139 White students at a privatecollege. Parental investment was reduced to threefactors (Family Composition, Family Security, andMarital Instability), the last of which was negativelycorrelated with GPA and positively correlated with SOI.SOI was a much stronger (negative) predictor of GPA inwomen, but not men, than ACT was. Results support thereproductive strategies approach and imply that prediction of academic difficulty (and genderdifferences therein) must confront reproductiveissues.

A differential staining protocol to investigate sperm selection in the mare`s reproductive tract after heterospermic insemination

Between housing and deep forest: Long-term population biology and dispersal of suburban Smooth snakes (Coronella austriaca)

Namesaking (naming a child after a parent or other relative) can be viewed as a mechanism to increase perceived parent-child similarity and, consequently, parental investment. Male and, to a lesser extent, firstborn children are more frequently namesakes than female and later-born children, respectively. However, a direct link between namesaking and parental investment has not been examined. In the present study, 632 participants (98 men and 534 women) from Central Europe indicated their first name, sex, birth order, number of siblings, sexual orientation, socioeconomic status, paternal and maternal first names, as well as relationship quality with, and time and financial investment they received from, both parents during childhood. Mixed-effects models revealed associations between namesaking and parental investment. However, the effect of namesaking often appeared significant only in interaction with specific predictors, such as sex and primogeniture. It suggests instead that namesaking has an additive effect-it enhances the effect of biological factors on parental investment. In general, we found evidence for the bias in parental investment linked to name similarity among both parents, and support for the hypothesis that namesaking serves as a mechanism to increase paternity confidence and, thus, paternal investment. The effect of namesaking influences only certain types of parental investment-namely, those at the level of relationship quality. In addition, nonheterosexual orientation was the strongest negative predictor of paternal investment. Our study extends the research on parental investment by showing that cultural mechanisms, such as namesaking, can also exert some influence on parental rearing behavior.

Growth of different body parts in humans is sensitive to different resource constraints that are mediated by parental investment. Parental investment can involve the expenditure of material, cognitive, and emotional resources on offspring. Cranial volume, an important predictor of cognitive ability, appears understudied in this context. We asked (1) whether there are associations between growth and family structure, self-reported estimates for resource availability, and sibling number; and (2) whether these constraints relate to head and body growth in a similar manner. We assessed the associations between parental investment, height, and cranial volume in a cross-sectional study of Estonian children (born 1980–87, aged 11–17). Height correlated negatively with the number of siblings but this association became negligible in a model controlling for birthweight, parental heights, and mother’s age at birth. Unlike height, cranial volume was unrelated to sibling number, but it was negatively associated with self-reported meat and general resource shortage. Cranial volume was related to family structure and paternal education. Children living with both birth-parents had larger heads than those living in families containing a step-parent. Since these family types did not differ with respect to meat or general resource shortage, our findings suggest that families including both genetic parents provide non-material benefits that stimulate predominantly cranial growth. For the studied developmental period, cranial volume appeared a more sensitive marker of growth constraints than height. The potential of using cranial volume for quantifying physical impact of non-material parental investment deserves further attention.

Many bird species adjust their offspring sex ratio as a response to environmental conditions or sexual dimorphism in size and dispersal. Offspring sex ratios may therefore vary among populations depending on the different demographic and ecological trajectories. We sampled Common Raven Corvus corax nestlings close to the fledging stage from three Central European regions to test for skewed secondary sex ratios and to investigate differences in sex ratios between populations that differ in recent recolonization history and breeding densities. Between 2005 and 2007, a total of 108 broods with 335 nestlings were sampled and their sex determined using molecular methods. We observed a mean of 3.1 (±1.2) nestlings per brood with no differences among nesting sites, years or regions. Nestling sex ratios were independent of the number of siblings. The overall secondary sex ratio was close to parity and did not differ between the variably structured populations.

The 1998 El Niño significantly reduced garden productivity in the Upper Orinoco region in Venezuela. Consequently, parents were forced to allocate food carefully to their children. Nutrition data collected from village children combined with genealogical data allowed the determination of which children suffered most, and whether the patterns of food distribution accorded with predictions from parental investment theory. For boys, three social variables accounted for over 70% of the variance in subcutaneous fat after controlling for age: number of siblings, age of the mother's youngest child, and whether the mother was the senior or junior co-wife, or was married monogamously. These results accord well with parental investment theory. Parents experiencing food stress faced a trade-off between quantity and quality, and between investing in younger versus older offspring. In addition, boys with access to more paternal investment (i.e. no stepmother) were better nourished. These variables did not account for any of the variance in female nutrition. Girls' nutrition was associated with the size of their patrilineage and the number of non-relatives in the village, suggesting that lineage politics may have played a role. An apparent lack of relationship between orphan status and nutrition is also interesting, given that orphans suffered high rates of skin flea infections. The large number of orphans being cared for by only two grandparents suggests that grooming time may have been the resource in short supply.

Although the clinical importance of chorionicity in twin pregnancies has been studied widely, the significance of perinatal determination of zygosity using molecular genetic analyses remains controversial. The purpose of this study was to determine the frequency and clinical significance of twin gestations according to zygosity and chorionicity in a Korean population. We enrolled 569 women who delivered twin newborns (> 24 weeks) at Seoul National University Hospital between 1999 and 2008. Chorionicity was established by histologic examination of placentae. Zygosity was determined with sex of neonates, chorionicity, and DNA analysis of umbilical cord blood. The frequency of dizygotic (DZ) twins was 71.0% (404/569 pairs) based on the opposite sex (238/404 [58.9%]) and DNA analyses (166/404 [41.1%]); that of monozygotic (MZ) twins was 29.0% (165/569), including monochorionic (MC) (72.1% [119/165]) and dichorionic (DC) twins (27.9% [46/165]), which was confirmed by DNA analyses. Among spontaneously conceived twins, the frequency of MZ twins was more than twice that of DZ twins. The risk of low birth weight was 1.8-fold higher among MZDC twins and 1.9-fold higher among MZMC twins than among DZDC twins (p < .05). Bronchopulmonary dysplasia occurred more frequently among MZMC twins than among DZDC twins (adjusted OR 8.42, 95% CI 1.82-39.08, p < .01). However, the frequencies of other neonatal morbidities were not significantly higher in the MZMC group than in the MZDC and DZDC groups. The perinatal mortality rate was 15 per 1000 total births in the DZDC twins, 20 per 1000 total births in the MZDC and 56 per 1000 total births in the MZMC (p < .01). Although monozygosity was shown to be a risk factor for perinatal death and accurate determination of zygosity plays a great role in the future consideration of organ transplantation and twin studies, the value of zygosity determination along with chorionicity in relation to overall neonatal morbidity was not definite.

news and update ISSN 1948-6596 commentary Estimating extinction risk under climate change: next-generation models simultaneously incorporate demography, dispersal, and biotic interactions Estimating species-level extinction risk under pro- jected future climate change is challenging. About ten years ago, Chris Thomas and colleagues used correlative species distribution models (SDMs) and future climate scenarios to estimate extinc- tion risk for >1100 animal and plant species (Thomas et al. 2004). They predicted that 15–37% of their sample species will be ‘committed to ex- tinction’ by 2050. The validity of such results is highly questionable because implausible assump- tions in correlative SDMs introduce large un- knowns into extinction risk forecasts (e.g., Dor- mann 2007). For example, a key assumption is that species’ distributions are at equilibrium with climate and that observed correlations with cli- mate will extend into the future. A further limita- tion is that population-level processes such as demographic rates, dispersal distances, and an- tagonistic or mutualistic interactions among spe- cies are not incorporated into SDMs (e.g., Hampe 2004). Nevertheless, recent biogeographical re- search may finally resolve some of these out- standing challenges (Kissling et al. 2012, Schurr et al. 2012, Travis et al. 2013, Wisz et al. 2013). In a groundbreaking addition to this grow- ing area of research, Fordham et al. (2013) pro- vide a framework for a next-generation model which simultaneously incorporates demography, dispersal, and biotic interactions into estimates of extinction risk under projected climate change. The authors apply this model to one of Europe´s most endangered mammals, the Iberian lynx (Lynx pardinus), which is restricted to isolated popula- tions in southwestern Spain. The modeling frame- work (Figure 1) is centered on demographic (metapopulation) simulations for the Iberian lynx and the European rabbit (Oryctolagus cuniculus), the latter being the main food source of the lynx. Metapopulation models were implemented as age- and sex-structured models for the Iberian lynx (with age and sex specific survival rates and fecundity estimates for age of reproduction, litter size, etc.) and as scalar type stochastic models for the rabbit (to estimate population growth rates without the need to include population age or stage structure). For both species, outputs from correlative SDMs (in annual time steps from 2000 –2100, using ensemble projections based on seven different SDM methods, seven climate change models, and two emission scenarios) were only used to estimate the carrying capacity for the demographic models. In other words, they were used as spatial layers describing climate suitabil- ity, i.e. as one of the components of habitat suit- ability for the two species (Figure 1). The coupling of SDMs with demographic models is a recent ad- vance (Keith et al. 2008), and represents a major step forward in predicting species-level extinction risk under climate change. Dispersal for both species is modelled using functions to determine the proportion of each population that disperses between grid cells or subpopulations (Figure 1). For the lynx, a declining function between subpopulations was used for distances up to 45 km; the maximum dispersal distance which has been empirically reported for this species. Furthermore, a remotely-sensed map (CORINE) was used to identify land cover types with different degrees of suitability for lynx dis- persal (from very good to highly unsuitable). Lynx dispersal was assumed to be stage-specific (young individuals versus adults) and density dependent (based on number of breeding-age individuals in a population), allowing for more detailed simulation of movement. For rabbit dispersal, a declining function up to a maximum dispersal distance of 15 km was used, closely approximating a 1% move- ment at distances of >3 km. Dispersal and move- ment data for both species were based on previ- ously published studies, highlighting the utility of empirical estimates of maximum dispersal dis- tances, movement behavior and habitat selection frontiers of biogeography 5.3, 2013 — © 2013 the authors; journal compilation © 2013 The International Biogeography Society

Life history parameters are essential when we consider appropriate strategy for conservation of wildlife based on population dynamics modelling. In this study, life history stage and sex-specific survival rates of a Japanese pond turtle (Mauremys japonica) population in foothill region were estimated. Life history was divided into three stages based on the age, separately for males and females, estimated by counting the number of annual rings on scutes: juvenile (1–2 years old), young adult (3–4), and adult (>5) in males, and juvenile (1–4), subadult (5–7), and adult (>8) in females. The median annual survival of subadult and adult females was 0.84 (95% credible interval: 0.54–0.99) and 0.94 (0.77–1.00), respectively, and higher than the survival of juvenile females. In contrast, adult survival of males was estimated as 0.79 (0.44–0.99), and it was higher than the survival of young adult and juvenile males. This study showed that the patterns of survivorship of M. japonica coincide with those of other chelonians.

Sex education is an important preventive and continuing approach to the care of preadolescent and adolescents. According to WHO young people aged 15–24 years acquire half of all new sexually transmitted disease and that 1 in 4 sexually active adolescent females have an STD, such as Chlamydia or human Papillomavirus (HPV). OBJECTIVES: To assess the pre-test and post-test knowledge level regarding sex education among adolescent girls. To evaluate the effectiveness of structured teaching program on sex education by comparing pre-test and post-test knowledge score. To associate the pre-test knowledge level on sex education among adolescent girls with selected demographic variables. METHODOLOGY: The research design is pre-experimental. The research approach is a Quantitative. The study was conducted in Shree Ambe Vidyalaya, Waghodia road, Vadodara. The sample consisted of 100 adolescent girls. Structure knowledge questionnaire was used to assess the knowledge. Structured teaching program on sex education was the intervention of the study. In the present study 100 adolescent girls selected using Probability Simple random sampling technique. FINDINGS OF THE STUDY: The overall Pretest mean knowledge score was found to be 45.9% with SD as 3.1. The overall Post test mean knowledge score was found to be 77.7% with SD as 2.9. The ‘t’ Test value was 31.49* (Significant at 5% level) which indicates the effectiveness of structure teaching on knowledge regarding sex education among adolescent girls There is a significant association between pre-test knowledge of mother with selected demographic variables such as age, educational status, religion, family type, monthly family income, education of father, source of information. However, the other selected demographic variables in the Pre test such as number of female siblings, ordinal position, education of mother, occupation of father and mother were found to be non-significant in the Pre test knowledge. CONCLUSION: The findings of the study makes the researcher hopeful that such initiatives has increased the adolescent girls’ knowledge regarding sex education.

Populations are often sexually dimorphic for demographic traits. Caswell (2001) has done a good job of highlighting some of these differences. The life expectancy of women exceeds that of men by about 10%. The life expectancy of female Belding's ground squirrels is about 25% greater than that of males (Sherman and Morton, 1984). Female black widow spiders (Deevey and Deevey, 1945) typically live 170% longer than males. However, I do not want to give the impression that females always outlive males. Males of many species of monogamous birds live longer than females (Darwin, 1871; Breitwisch, 1989), for reasons that vary from differences in natal dispersal (Greenwood and Harvey, 1982) to differences in parental investment. Differences in survivorship frequently manifest themselves as a skewed sex ratio in the population. Some species show sex-based differences in the age of maturity. Female sperm whales attain sexual maturity at 7 to 9 years. Males may become physiologically mature at 19 years, but do not reach social maturity for 25 to 27 years (Nowak, 1991). Most organisms have sex-based differences in fecundity. As a result, life tables and demographic models for males and for females often give different predictions. Kuczynski (1931) calculated the male and female net reproductive rates for France for 1920–1923. The male rate was 1.194 and the female rate was 0.977. If one were to follow these calculations to their logical conclusion, one would now expect France to consist entirely of men ⊨ Kuczynski attributed the difference in the rates to the skew in sex ratio caused by the First World War.

Skewed adult sex ratios sometimes occur in populations of free‐living animals yet the proximate mechanisms, timing of sex‐biases, and the selective agents contributing to skew remain a source of debate with contradictory evidence from different systems. We investigated potential mechanisms contributing to sex biases in a population of herring gulls with an apparent female skew in the adult population. Theory predicts that skewed adult sex ratios will adaptively lead to skewed offspring sex ratios to restore balance in the effective breeding population. Parents may also adaptively bias offspring sex ratios to increase their own fitness in response to environmental factors. Therefore, we expected to detect skewed sex ratios either at hatching or at fledging as parents invest differentially in offspring of different sexes. We sampled complete clutches (n = 336 chicks) at hatching to quantify potential skews in sex ratios by position in the hatch order, time of season, year, and nesting context (nest density), finding no departure from equal sex ratios at hatching related to any of these factors. Further, we sampled 258 chicks at near‐fledging to investigate potential sex biases in survival at the chick stage. Again, no biases in sex ratios were recorded. Male offspring were favored in this population via greater maternal investment in eggs carrying male embryos and greater parental provisioning of male offspring which reached greater sizes by fledging. Despite the advantages realized by male offspring, females were equally as likely to fledge as males. Thus, biased adult sex ratios apparently arise in the post‐fledging and pre‐recruitment stage in our population.