Estimated Sex Ratio Research Articles

Fibromyalgia diagnosis and biased assessment: Sex, prevalence and bias.

PurposeMultiple clinical and epidemiological studies have provided estimates of fibromyalgia prevalence and sex ratio, but different criteria sets and methodology, as well as bias, have led to widely varying (0.4%->11%) estimates of prevalence and female predominance (>90% to <61%). In general, studies have failed to distinguish Criteria based fibromyalgia (CritFM) from Clinical fibromyalgia (ClinFM). In the current study we compare CritFM with ClinFM to investigate gender and other biases in the diagnosis of fibromyalgia.MethodsWe used a rheumatic disease databank and 2016 fibromyalgia criteria to study prevalence and sex ratios in a selection biased sample of 1761 referred and diagnosed fibromyalgia patients and in an unbiased sample of 4342 patients with no diagnosis with respect to fibromyalgia. We compared diagnostic and clinical variables according to gender, and we reanalyzed a German population study (GPS) (n = 2435) using revised 2016 criteria for fibromyalgia.ResultsIn the selection-biased sample of referred patients with fibromyalgia, more than 90% were women. However, when an unselected sample of rheumatoid arthritis (RA) patients was studied for the presence of fibromyalgia, women represented 58.7% of fibromyalgia cases. Women had slightly more symptoms than men, including generalized pain (36.8% vs. 32.4%), count of 37 symptoms (4.7 vs. 3.7) and mean polysymptomatic distress scores (10.2 vs. 8.2). We also found a linear relation between the probability of being females and fibromyalgia and fibromyalgia severity. Women in the GPS represented 59.2% of cases.DiscussionThe perception of fibromyalgia as almost exclusively (≥90%) a women’s disorder is not supported by data in unbiased studies. Using validated self-report criteria and unbiased selection, the female proportion of fibromyalgia cases was ≤60% in the unbiased studies, and the observed CritFM prevalence of fibromyalgia in the GPS was ~2%. ClinFM is the public face of fibromyalgia, but is severely affected by selection and confirmation bias in the clinic and publications, underestimating men with fibromyalgia and overestimating women. We recommend the use of 2016 fibromyalgia criteria for clinical diagnosis and epidemiology because of its updated scoring and generalized pain requirement. Fibromyalgia and generalized pain positivity, widespread pain (WPI), symptom severity scale (SSS) and polysymptomatic distress (PSD) scale should always be reported.

Using Approximate Bayesian Computation to infer sex ratios from acoustic data.

Population sex ratios are of high ecological relevance, but are challenging to determine in species lacking conspicuous external cues indicating their sex. Acoustic sexing is an option if vocalizations differ between sexes, but is precluded by overlapping distributions of the values of male and female vocalizations in many species. A method allowing the inference of sex ratios despite such an overlap will therefore greatly increase the information extractable from acoustic data. To meet this demand, we developed a novel approach using Approximate Bayesian Computation (ABC) to infer the sex ratio of populations from acoustic data. Additionally, parameters characterizing the male and female distribution of acoustic values (mean and standard deviation) are inferred. This information is then used to probabilistically assign a sex to a single acoustic signal. We furthermore develop a simpler means of sex ratio estimation based on the exclusion of calls from the overlap zone. Applying our methods to simulated data demonstrates that sex ratio and acoustic parameter characteristics of males and females are reliably inferred by the ABC approach. Applying both the ABC and the exclusion method to empirical datasets (echolocation calls recorded in colonies of lesser horseshoe bats, Rhinolophus hipposideros) provides similar sex ratios as molecular sexing. Our methods aim to facilitate evidence-based conservation, and to benefit scientists investigating ecological or conservation questions related to sex- or group specific behaviour across a wide range of organisms emitting acoustic signals. The developed methodology is non-invasive, low-cost and time-efficient, thus allowing the study of many sites and individuals. We provide an R-script for the easy application of the method and discuss potential future extensions and fields of applications. The script can be easily adapted to account for numerous biological systems by adjusting the type and number of groups to be distinguished (e.g. age, social rank, cryptic species) and the acoustic parameters investigated.

Trends in female and male drunken driving prevalence over thirty years: Triangulating diverse sources of evidence (1985–2015)

IntroductionWomen have lower rates of drunken driving than men, but their share of arrests has been climbing since 1985. These trends may stem from changes in women's lives that lead to more drinking and driving, or to greater reductions in male drinking and driving. Alternatively, changes in policy and enforcement that focus on less intoxicated offenders may inadvertently target female-typical offending patterns. This paper tracked male and female drunken driving rates and the DUI sex ratio in the United States from 1985 to 2015 across three data sources. MethodsThe sex ratio and prevalence estimates were derived from official arrest statistics from Uniform Crime Reports, self-reports from the Centers for Disease Control and Prevention, and traffic fatality data from the National Highway and Transportation Safety Administration. Rates were assessed for four age groups (18–20, 21–34, 35–49, and 50–64), and drunken driving trends tested using Augmented Dickey-Fuller time-series methods. ResultsDecreases in DUI rates stagnated over the first decade of 2000, but have again begun to decline, according to self-reports and traffic fatality data, for all sex-by-age groups. Still, the gender gap in DUI arrests continues to narrow. From 1990 to the early 2000s, changes in social control that made female DUI more visible narrowed the gender gap in arrests. In more recent years, narrowing of the gap is due primarily to male rates declining more steeply than female rates. ConclusionResults indicate that we need more research to understand why female declines have not kept pace with male declines and perhaps more targeted prevention efforts aimed at women.

Non-invasive genetic censusing and monitoring of primate populations.

Knowing the density or abundance of primate populations is essential for their conservation management and contextualizing socio-demographic and behavioral observations. When direct counts of animals are not possible, genetic analysis of non-invasive samples collected from wildlife populations allows estimates of population size with higher accuracy and precision than is possible using indirect signs. Furthermore, in contrast to traditional indirect survey methods, prolonged or periodic genetic sampling across months or years enables inference of group membership, movement, dynamics, and some kin relationships. Data may also be used to estimate sex ratios, sex differences in dispersal distances, and detect gene flow among locations. Recent advances in capture-recapture models have further improved the precision of population estimates derived from non-invasive samples. Simulations using these methods have shown that the confidence interval of point estimates includes the true population size when assumptions of the models are met, and therefore this range of population size minima and maxima should be emphasized in population monitoring studies. Innovations such as the use of sniffer dogs or anti-poaching patrols for sample collection are important to ensure adequate sampling, and the expected development of efficient and cost-effective genotyping by sequencing methods for DNAs derived from non-invasive samples will automate and speed analyses.

Delimitation of the embryonic thermosensitive period for sex determination using an embryo growth model reveals a potential bias for sex ratio prediction in turtles

The sexual phenotype of the gonad is dependent on incubation temperature in many turtles, all crocodilians, and some lepidosaurians. At hatching, identification of sexual phenotype is impossible without sacrificing the neonates. For this reason, a general method to infer sexual phenotype from incubation temperatures is needed. Temperature influences sex determination during a specific period of the embryonic development, starting when the gonad begins to form. At constant incubation temperatures, this thermosensitive period for sex determination (TSP) is located at the middle third of incubation duration (MTID). When temperature fluctuates, the position of the thermosensitive period for sex determination can be shifted from the MTID because embryo growth is affected by temperature. A method is proposed to locate the thermosensitive period for sex determination based on modelling the embryo growth, allowing its precise identification from a natural regime of temperatures. Results from natural nests and simulations show that the approximation of the thermosensitive period for sex determination to the middle third of incubation duration may create a quasi-systematic bias to lower temperatures when computing the average incubation temperature during this period and thus a male-bias for sex ratio estimate.

Short heatwaves during fluctuating incubation regimes produce females under temperature-dependent sex determination with implications for sex ratios in nature

Patterns of temperature fluctuations in nature affect numerous biological processes, yet, empirical studies often utilize constant temperature treatments. This can limit our understanding of how thermally sensitive species respond to ecologically relevant temperatures. Research on turtles with temperature-dependent sex determination (TSD) provides good examples of this, since nest temperatures from many populations rarely exceed those necessary to produce females under constant laboratory conditions. We hypothesized that exposure to brief periods of warm temperatures (i.e., heat waves) are integral to sex determination in species with TSD, which requires tests that move beyond constant temperatures. We exposed Trachemys scripta embryos from multiple populations and across the nesting season to heat waves of variable durations and quantified sex ratios. We found that embryos from all populations were highly sensitive to brief exposures to female producing temperatures; only 7.9 days of exposure produced a 50:50 sex ratio, but the response varied across the nesting season. From these findings, a model was developed to estimate sex ratios from field temperature traces, and this model outperformed traditional methods. Overall, these results enhance our understanding of TSD and emphasize the importance of using biologically relevant temperatures when studying thermally sensitive processes.

Skewed sex ratio in a forest salamander: artefact of the different capture probabilities between sexes or actual ecological trait?

Sex ratio is an essential demographic parameter and distortions from a balanced sex ratio may have contrasting effects on the population dynamics. However, observation of distorted sex ratio using counts or captures may reflect an actual ecological trait of the studied population but may also be an artefact due to different capture probabilities of males and females. We compared results obtained from Counts and Capture-Marking-Recapture (CMR) on both sexes in a population of a forest dwelling salamander, Salamandrina perspicillata, and we investigated if males and females had different capture probabilities. We surveyed available literature to compare information on sex ratio from other populations of S. perspicillata. The sex ratio from our counts was 0.65 and was significantly male-biased as reported in other studies. The estimated sex ratio from CMR data was 0.57. Although males showed higher recapture rates than females in every capture session, these differences were not statistically significant. Therefore, the skewed sex ratio towards males is not only an artefact due to different capture probabilities between males and females but reflects an actual demographic trait, although the magnitude of the skeweness was overestimated by counts.

Measurement and modelling of primary sex ratios for species with temperature-dependent sex determination.

For many oviparous animals, incubation temperature influences sex through temperature-dependent sex determination (TSD). Although climate change may skew sex ratios in species with TSD, few available methods predict sex under natural conditions, fewer still are based on mechanistic hypotheses of development, and field tests of existing methods are rare. We propose a new approach that calculates the probability of masculinization (PM) in natural nests. This approach subsumes the mechanistic hypotheses describing the outcome of TSD, by integrating embryonic development with the temperature-dependent reaction norm for sex determination. Further, we modify a commonly used method of sex ratio estimation, the constant temperature equivalent (CTE), to provide quantitative estimates of sex ratios. We test our new approaches using snapping turtles (Chelydra serpentina). We experimentally manipulated nests in the field, and found that the PM method is better supported than the modified CTE, explaining 69% of the variation in sex ratios across 27 semi-natural nests. Next, we used the PM method to predict variation in sex ratios across 14 natural nests over 2years, explaining 67% of the variation. We suggest that the PM approach is effective and broadly applicable to species with TSD, particularly for forecasting how sex ratios may respond to climate change. Interestingly, we also found that the modified CTE explained up to 64% of variation in sex ratios in a Type II TSD species, suggesting that our modifications will be useful for future research. Finally, our data suggest that the Algonquin Park population of snapping turtles possesses resilience to biased sex ratios under climate change.

Hydric environmental effects on turtle development and sex ratio

Experimental and field studies of different turtle species suggest that moisture influences embryonic development and sex ratios, wetter substrates tend to produce more males, and drier substrates produce more females. In this study, we used Trachemys scripta elegans to test the effect of moisture on embryonic development and sex ratios. T. s. elegans eggs were incubated under different temperature and moisture regimes. We monitored embryonic development until stage 22 (after sex determination) and, for the first time, we estimated sex ratios using a male-specific transcriptional molecular marker, Sox9. Among treatments, we found differences in developmental rates, egg mass, and sex ratio. Embryos developed slowly in cooler and wetter sand substrate while water uptake by the eggs was significantly greater on wetter substrates. Developmental differences were due to moisture interacting with temperature where increased water content of the sand resulted in temperatures that were 2–3°C lower than air temperatures. The coolest and the wettest substrates produced 100% males compared to 42% males from the warmest and driest treatment. Further, we found that embryonic growth appears to be more sensitive to temperature at earlier stages of development and to moisture at later stages. This study shows how moisture may change the incubation conditions inside nests by changing the temperature experienced by eggs, which affects development, growth and sex ratios. The results of this study highlight the importance of including moisture conditions when predicting embryo growth and sex ratios and in developing proxies of embryonic development.

Detection of Plasmodium falciparum male and female gametocytes and determination of parasite sex ratio in human endemic populations by novel, cheap and robust RTqPCR assays

BackgroundThe presence of Plasmodium falciparum gametocytes in peripheral blood is essential for human to mosquito parasite transmission. The detection of submicroscopic infections with gametocytes and the estimation of the gametocyte sex ratio are crucial to assess the human host potential ability to infect mosquitoes and transmit malaria parasites.Aim and objectivesThe aim of this work was to develop sensitive and cheap Real Time qPCR assays for large-scale epidemiological surveys, based on detection and amplification of gametocyte sex specific transcripts selected from the literature: the female-specific pfs25 and pf glycerol kinase (pfGK) and the male-specific pfs230p and pf13 transcripts.MethodsRTqPCR assays were used to test the gametocyte- and sex-specific expression of the target genes using asexual stages of the gametocyteless parasite clone F12 and FACS purified male and female gametocytes of the PfDynGFP/P47mCherry line. Assays were performed on 50 blood samples collected during an epidemiological survey in the Soumousso village, Burkina Faso, West-Africa, and amplification of the human housekeeping gene 18S rRNA was employed to normalize RNA sample variability.ResultsSYBR Green assays were developed that showed higher sensitivity compared to Taqman assays at a reduced cost. RTqPCR results confirmed that expression of pfs25 and pfs230p are female and male-specific, respectively, and introduced two novel markers, the female-specific pfGK and the male-specific pf13. A formula was derived to calculate the ratio of male to female gametocytes based on the ratio of male to female transcript copy number. Use of these assays in the field samples showed, as expected, a higher sensitivity of RTqPCR compared to microscopy. Importantly, similar values of gametocyte sex-ratio were obtained in the field samples based on the four different target combinations.ConclusionNovel, sensitive, cheap and robust molecular assays were developed for the detection and quantification of female and male P. falciparum gametocytes. In particular, the RTqPCR assays based on the female-specific pfs25 and the newly described male gametocyte-specific pf13 transcripts, including normalization by the human 18S, reliably assess presence and abundance of female and male gametocytes and enable to determine their sex-ratio in human subjects in endemic areas.

Sex ratio estimates for species with temperature-dependent sex determination differ according to the proxy used

Knowledge of the sex ratio of a population is crucial to understand their structure and dynamics. For species, such as marine turtles, with temperature-dependent sex determination, this knowledge provides a baseline in advance of climate change. Determining the primary sex ratio for marine turtle populations is challenging since offspring lack sexually dimorphic external characteristics. Therefore several proxies have been used to estimate the primary sex ratio of marine turtle populations. However, no study to date has compared estimations of sex ratio when using different proxies to determine the most accurate and to detect potential bias. To address this, we estimated the sex ratio of natural loggerhead, Caretta caretta, nests using 8 different proxies: two based on constant temperature equivalent (average of temperature or average temperature weighted by the growth of embryos during each time step) both for three developmental periods (the whole incubation, the middle third of incubation and the middle third of development) as well as two proxies based on incubation duration (duration of the whole incubation and of the middle third of development). Sex ratio estimates differed greatly depending on the proxy being used. Here we discuss the differences among proxies based on the biological relevance of underlying hypotheses and highlight the need for studies to accurately determine the thermosensitive period and to obtain appropriate estimates of embryo growth rate to estimate marine turtle sex ratio.

Utilizing External Features and a Consensus Field‐Based Approach to Determine Sex of Lake Michigan Yellow Perch

AbstractUnderstanding fluctuations in population sex ratios is important for evaluating the effects of changes in population demographics and for making informed management decisions. The Yellow Perch Perca flavescens, an important sport fish in Lake Michigan, undergoes sexually dimorphic growth, likely resulting in differing vulnerabilities to angler harvest. However, sex ratio data from angler‐harvested fish have not been collected because of the handling time and intrusiveness of the methods for distinguishing sexes. We utilized digital photographs of the urogenital papilla (UGP) from known‐sex Yellow Perch to establish a method whereby UGP shape could be used to rapidly, accurately, and inexpensively determine the sex of Yellow Perch. Overall, 88.1% of Yellow Perch examined were assigned to the correct sex, and the sex ratio estimate of 48:87 (female : male) did not differ significantly from the known sex ratio of 46:89. Classification success was not affected by fish sex, TL, or month of collection. Our results demonstrate accurate, rapid, inexpensive, and nonlethal applicability of this method across a wide range of sizes and geographic and temporal scales. Applying this methodology will permit accurate sex ratio estimates for angler‐harvested Yellow Perch, which can be used to better understand harvest composition and its implications for management.Received February 17, 2017; accepted June 9, 2017 Published online August 31, 2017

Correcting for unequal catchability in sex ratio and population size estimates

Wildlife populations often exhibit unequal catchability between subgroups such as males and females. This heterogeneity of capture probabilities can bias both population size and sex ratio estimates. Several authors have suggested that this problem can be overcome by treating males and females as separate populations and calculating a population estimate for each of them. However, this suggestion has received little testing, and many researchers do not implement it. Therefore, we used two simulations to test the utility of this method. One simulated a closed population, while the other simulated an open population and used the robust design to calculate population sizes. We tested both simulations with multiple levels of heterogeneity, and we used a third simulation to test several methods for detecting heterogeneity of capture probabilities. We found that treating males and females as separate populations produced more accurate population and sex ratio estimates. The benefits of this method were particularly pronounced for sex ratio estimates. When males and females were included as a single population, the sex ratio estimates became inaccurate when even slight heterogeneity was present, but when males and females were treated separately, the estimates were accurate even when large biases were present. Nevertheless, treating males and females separately reduced precision, and this method may not be appropriate when capture and recapture rates are low. None of the methods for detecting heterogeneity were robust, and we do not recommend that researchers rely on them. Rather, we suggest separating populations by sex, age, or other subgroups whenever sample sizes permit.

Reproductive biology of the freshwater drum Aplodinotus grunniens in Tabasco, Mexico

Aplodinotus grunniens supports a sustained artisanal shery in the Usumacinta River; however, there are few studies to understand the population dynamics of the species. Relevant aspects of the reproductive biology were documented over an annual cycle, using 593 specimens captured with seine nets. The results indicate that females had a median TL of 32.05 cm, while males had 29.71 cm. The estimated sex ratio was 1.2:1 (males: females). The length-weight relationship showed signi cant difference between sexes, observing an allometric-type growth represented by TW=0.0013(TL)3.5985 with 89.17 % of the data variability explained by the model. Gonadosomatic index (GSI) in females was higher in September (4.29), with males displaying a higher GSI in October (1.02). The highest HSI increase in females was observed in October (1.0). The estimated relative fecundity was 138.74 (± 74.30) oocytes/g of female weight. The macroscopic analysis of gonads indicates that the highest frequency of mature females occurs in June (75 %), while in males it takes place in March and June (35 %). The estimated L 50 for females was 31.89 cm (TL) and 28.78 cm (TL) for males. Though A. grunniens reproduces throughout the year, reproductive peaks coincide with the period when the river level decreases, and shing increases considerably. Hence, preventive measures must be applied in regards to the size of the species at capture and the exploitation volumes of this resource.

Noninvasive genetic spatial capture‐recapture for estimating deer population abundance

ABSTRACTInformed management of wildlife populations requires the accurate estimation of abundance, sex ratio, and other population parameters. For deer (Odocoileus spp.), the use of closed‐population, capture‐recapture (CR) methods, in conjunction with noninvasive DNA sampling, has become increasingly practical, but, up to now, these methods have been used in a non‐spatial modeling framework, which has limited their utility for population‐level inferences. In particular, extrapolation of plot‐level CR abundance estimates to the population required the use of multipliers of unknown reliability and potential bias. Spatially explicit capture‐recapture (SCR) models provide an integrated framework for directly estimating density as a function of spatial and habitat variables at landscape scales. We used fecal DNA samples in conjunction with SCR to estimate density, sex ratio, and habitat correlates to density for a mule deer (O. hemionus) population across a large (∼500 km2) area in the central Sierra Nevada Range, California, USA during 2013 and 2014. We surveyed 24 random transects within 4 30‐km2 sites representative of the study area. Based on 411 samples genotyped at a sex marker and 8–10 microsatellite loci, the sex‐ratio for the study area was 62 (95% CI = 41–93) males/100 females in 2013 and 65 (95% CI = 45–94) males/100 females in 2014. Using SCR, we estimated density at 5.0 (95% CI = 2.3–7.8) deer/km2 in 2013 and 5.1 (95% CI = 3.1–7.2) deer/km2 in 2014. In comparison, non‐spatial CR analysis produced density estimates on average 60% higher, likely reflecting bias resulting from use of the commonly employed mean maximum recapture distance (MMRD) to estimate effective sampling area. The SCR models indicated that density was effectively homogeneous throughout the study area, with no strong relationship to habitat correlates. Altogether, these results demonstrate the utility of noninvasive fecal DNA methods in a SCR framework for estimation of abundance and density in deer populations at landscape scales. © 2017 The Wildlife Society

Sex and age factors in neuroleptic malignant syndrome diagnosis frequency

IntroductionIt is not known whether sex and age are risk factors for neuroleptic malignant syndrome (NMS).ObjectivesTo examine sex and age distributions in NMS patients based on a systematic review of the literature.AimsEstimate the sex-specific relative risk of an NMS diagnosis.MethodsEMBASE and PubMed databases were searched in November 2014 using broad, unrestricted criteria to identify any published observation of NMS. Any physically (online or hard copy) accessible and interpretable (using language translation software) report published from January 1, 1998 through November 1, 2014 was considered for inclusion. Secondary sources (e.g., reviews) were included when primary sources could not be accessed. All cases for which the patient's sex or the sample's sex distribution was provided were included, except for redundant reports and cases in which NMS was not the most likely clinical diagnosis. Sex ratio and age distributions were examined using standard graphical techniques and measures of association.ResultsTwenty-eight independent NMS sex ratio estimates were included. Most sex ratio estimates (75%) indicated male preponderance, with a median of 1.47 (95% CI: 1.20–1.80). NMS incidence peaked at age 20–25 years and declined steadily thereafter; males consistently outnumbered females at all age intervals. Major study limitations are the heterogeneity of case ascertainment procedures and the potential for publication bias.ConclusionsNMS patients are 50% more likely to be males, and NMS is most likely to occur in young adulthood. Men, and all young adults, appear to be at increased risk for NMS.Disclosure of interestThe authors have not supplied their declaration of competing interest.

Length-weight relationships, sex ratio and growth estimates for five sympatric sillaginids (Pisces) from the northern Arabian Sea coast

Five species were collected (n = sample sizes in parentheses): Sillago arabica (8), S. attenuata (26), S. indica (971), S. sihama (77) and Sillaginopodys chondropus (18) from the northern Arabian Sea coast of Pakistan. Specimens were caught with gill nets (mesh size 2.5 cm knot-to-knot) by medium-sized commercial fishing vessels from September 2015 to April 2016. The parameter slope (b) in the length–weight relationships ranged from 2.44−3.21 for sexes grouped. Sex ratios were male-biased in all species and deviated from an ideal 1:1 sex ratio. Applying the von Bertalanffy function growth coefficient, reasonable growth (K = 0.890 year−1) was estimated for Sillago sihama, whereas this was slower in S. attenuata (0.24 year−1). Goodness of fit range was Rn = 0.32–1.0. This study provides a new reference for LWRs in three of the species (S. arabica, S. attenuata, and S. chondropus), with a new maximum total length for S. indica to add to FishBase. The data presented here on the five sillaginid species can be useful for local management and conservation of these species.

A systematic review of sex and age factors in neuroleptic malignant syndrome diagnosis frequency

To examine sex and age distributions in neuroleptic malignant syndrome (NMS) patients based on a systematic literature review. EMBASE and PubMed databases were searched to identify any observation of NMS published from January 1, 1998 through November 1, 2014 that was accessible and interpretable (using language translation software). Redundant and equivocal reports were excluded. Sex ratio and age distributions were examined using standard graphical techniques and measures of association. Twenty-eight independent sex ratio estimates were included. Males predominated in most (75%) estimates with an overall median sex ratio of 1.47 (95% CI, 1.20-1.80). NMS incidence peaked at age 20-25 years and declined steadily thereafter, with males consistently outnumbering females at all but the oldest age intervals. NMS patients are 50% more likely to be males, and NMS is most likely to occur in young adulthood.

Effective population size of an offshore population of bottlenose dolphins, Tursiops truncatus, from the São Pedro and São Paulo Archipelago, Brazil

The São Pedro and São Paulo Archipelago (SPSPA) (00°56’N, 29°22’W) lies approximately 1010km northeast off the coast of Rio Grande do Norte State in Brazilian waters. Recently, through photo-identification and group size analysis, around 20-30 individual bottlenose dolphins, Tursiops truncatus, from SPSPA were recognized as a resident, and potentially genetically isolated, population. The effective population size (Ne), not the census number (Nc), as well the sex ratio, are of primary concern from an evolutionary and conservation management perspectives. The estimate of Ne reflects the number of individuals responsible for the maintenance of genetic diversity of a species or population as well its evolutionary potential. For this reason, we present here the first Ne and sex ratio estimates for the bottlenose dolphin population from SPSPA. Sex was molecularly determined for 19 biopsy samples collected from bottlenose dolphins from SPSPA between January and February 2005. The Newas estimated by direct counting of reproductive adults sexed by DNA analysis. The resulting Ne was 12 individuals and the sex ratio was 1.11 male to 1 female, however, it was not significantly different from the expected 1:1 ratio (χ2 test, α= 0.05; df = 1). The effective population size based on the genetic diversity of 19 sequences of the mtDNA control region resulted in a female effective population size of 223 individuals, and the total long-term effective size of ~470 individuals. We believe that the estimated Ne for the SPSPA population is a critical value, because it is significantly lower than the mean minimum viable population (MVP) suggested for vertebrates (around 5000 breeding age adults). This small Ne is of great concern and should be taken into account in future management plans to ensure the conservation and protection of this small population at SPSPA.

Sexually dimorphic gene expressions in eels: useful markers for early sex assessment in a conservation context.

Environmental sex determination (ESD) has been detected in a range of vertebrate reptile and fish species. Eels are characterized by an ESD that occurs relatively late, since sex cannot be histologically determined before individuals reach 28 cm. Because several eel species are at risk of extinction, assessing sex at the earliest stage is a crucial management issue. Based on preliminary results of RNA sequencing, we targeted genes susceptible to be differentially expressed between ovaries and testis at different stages of development. Using qPCR, we detected testis-specific expressions of dmrt1, amh, gsdf and pre-miR202 and ovary-specific expressions were obtained for zar1, zp3 and foxn5. We showed that gene expressions in the gonad of intersexual eels were quite similar to those of males, supporting the idea that intersexual eels represent a transitional stage towards testicular differentiation. To assess whether these genes would be effective early molecular markers, we sampled juvenile eels in two locations with highly skewed sex ratios. The combined expression of six of these genes allowed the discrimination of groups according to their potential future sex and thus this appears to be a useful tool to estimate sex ratios of undifferentiated juvenile eels.