Estimating the age structure of a population of brushtail possums (Trichosurus vulpecula) by comparing tooth wear and cementum lines

2011 ◽  
Vol 33 (1) ◽  
pp. 52 ◽  
Author(s):  
Cheryl A. Lohr ◽  
Tammy Esmaili ◽  
Harriet Mills ◽  
Roberta Bencini
Keyword(s):  
Western Australia ◽  
Age Structure ◽  
Wild Population ◽  
Age Distribution ◽  
Tooth Wear ◽  
Trichosurus Vulpecula ◽  
Rank Regression ◽  
Parametric Data ◽  
Free Ranging ◽  
The Relationship

We used cementum lines from a sample of possums to calibrate tooth wear patterns in free-ranging common brushtail possums (Trichosurus vulpecula) to estimate of the age structure of a wild population of the species living at the Perth Zoo, Western Australia. We assessed patterns of tooth wear and incremental cementum lines in teeth extracted from 40 possums via necropsy. Rank regression for non-parametric data revealed a weak relationship between the number of cementum lines per tooth (y), which was assumed to correspond to the age of the possums (in years), and tooth wear (males: age = 0.51x + 3.4, r2 = 0.098, n = 27; females: age = 1.17x + 0.35, r2 = 0.345, n = 45). We used these relationships and the tooth wear pattern of 149 live possums caught at Perth Zoo to develop an estimate of the age structure of the population. Most (63.1%) possums were between 4 and 6 years of age. Very few young (1–2 years) or old (6–8 years) possums were caught at Perth Zoo. These results yielded an approximate age distribution for possums within Perth Zoo and should be used with caution because the relationship between the number of cementum lines and tooth wear was weak.

Estimating the age of western grey kangaroos (Macropus fuliginosus ocydromus)

2018 ◽  
Vol 40 (2) ◽  
pp. 254 ◽  
Author(s):  
Chris Mayberry ◽  
Roberta Bencini ◽  
Peter R. Mawson ◽  
Shane K. Maloney
Keyword(s):  
Linear Relationship ◽  
Western Australia ◽  
Age Structure ◽  
Wild Population ◽  
Target Population ◽  
Population Management ◽  
Eye Lens ◽  
Foot Length

Scientific studies and population management may benefit from knowledge of the age structure of a target population. We evaluated traditional and newly developed methods of estimating the age of kangaroos with data from 336 western grey kangaroos (Macropus fuliginosus) culled from a wild population in south-western Australia. We compared their ages based on molar progression with data on head, leg, and foot length, a balanced sum of all three measures, dried eye-lens weight, and molar wear score, and derived formulae to estimate age from each variable. Molar wear score has a linear relationship to molar progression and therefore leads to similar estimations of age, but requires only one complete arcade of molars. Because the relationships between age and the lengths of head, foot and leg are curvilinear, these become less reliable indicators of age with increasing age but the accuracy can be improved by considering a combination of the lengths of head, foot, and leg. Estimation of age from dried lens weight is more accurate than estimation from morphometry. The use of morphometry to estimate the age of kangaroos older than two years is more reliable than previously thought and requisite data can be collected from live animals. Where lethal methods are needed to collect samples, a largely intact skull, a single arcade of molars, or the lens extracted from one eye can reliably be used to estimate age.

Factors that contribute to urban–rural gradients in risk of schizophrenia: Comparing Danish and Western Australian registers

2021 ◽  
pp. 000486742110096
Author(s):  
Oleguer Plana-Ripoll ◽  
Patsy Di Prinzio ◽  
John J McGrath ◽  
Preben B Mortensen ◽  
Vera A Morgan
Keyword(s):  
Confidence Interval ◽  
Western Australia ◽  
Urban Areas ◽  
Proportional Hazards ◽  
Cox Proportional Hazards ◽  
Hazard Ratio ◽  
Indigenous Status ◽  
Increased Risk ◽  
The Relationship ◽  
Western Australian

Introduction: An association between schizophrenia and urbanicity has long been observed, with studies in many countries, including several from Denmark, reporting that individuals born/raised in densely populated urban settings have an increased risk of developing schizophrenia compared to those born/raised in rural settings. However, these findings have not been replicated in all studies. In particular, a Western Australian study showed a gradient in the opposite direction which disappeared after adjustment for covariates. Given the different findings for Denmark and Western Australia, our aim was to investigate the relationship between schizophrenia and urbanicity in these two regions to determine which factors may be influencing the relationship. Methods: We used population-based cohorts of children born alive between 1980 and 2001 in Western Australia ( N = 428,784) and Denmark ( N = 1,357,874). Children were categorised according to the level of urbanicity of their mother’s residence at time of birth and followed-up through to 30 June 2015. Linkage to State-based registers provided information on schizophrenia diagnosis and a range of covariates. Rates of being diagnosed with schizophrenia for each category of urbanicity were estimated using Cox proportional hazards models adjusted for covariates. Results: During follow-up, 1618 (0.4%) children in Western Australia and 11,875 (0.9%) children in Denmark were diagnosed with schizophrenia. In Western Australia, those born in the most remote areas did not experience lower rates of schizophrenia than those born in the most urban areas (hazard ratio = 1.02 [95% confidence interval: 0.81, 1.29]), unlike their Danish counterparts (hazard ratio = 0.62 [95% confidence interval: 0.58, 0.66]). However, when the Western Australian cohort was restricted to children of non-Aboriginal Indigenous status, results were consistent with Danish findings (hazard ratio = 0.46 [95% confidence interval: 0.29, 0.72]). Discussion: Our study highlights the potential for disadvantaged subgroups to mask the contribution of urban-related risk factors to risk of schizophrenia and the importance of stratified analysis in such cases.

scholarly journals The Function of Mounts in Free-Ranging Barbary Macaques (Macaca sylvanus)

2021 ◽  
Author(s):  
Simone Anzá ◽  
Bonaventura Majolo ◽  
Federica Amici
Keyword(s):  
Social Relationships ◽  
Sexual Behaviors ◽  
Agonistic Behavior ◽  
Social Bond ◽  
Macaca Sylvanus ◽  
Barbary Macaques ◽  
The Social ◽  
Rank Difference ◽  
Free Ranging ◽  
The Relationship

AbstractGenerally, nonreproductive sex is thought to act as “social grease,” facilitating peaceful coexistence between subjects that lack close genetic ties. However, specifc nonreproductive sexual behaviors may fulfill different functions. With this study, we aimed to test whether nonreproductive mounts in Barbary macaques are used to 1) assert dominance, 2) reinforce social relationships, and/or 3) solve conflicts. We analyzed nonreproductive mounts (N = 236) and postmount behavior in both aggressive and nonaggressive contexts, in 118 individuals belonging to two semi-free-ranging groups at La Montagne des Singes (France). As predicted by the dominance assertion hypothesis, the probability to be the mounter increased with rank difference, especially in aggressive contexts (increasing from 0.066 to 0.797 in nonaggressive contexts, and from 0.011 to 0.969 in aggressive contexts, when the rank difference was minimal vs. maximal). The strength of the social bond did not significantly predict the proportion of mounts across dyads in nonaggressive contexts, providing no support for the relationship reinforcement hypothesis. Finally, in support of the conflict resolution hypothesis, when individuals engaged in postconflict mounts, 1) the probability of being involved in further aggression decreased from 0.825 to 0.517, while 2) the probability of being involved in grooming interactions with each other increased from 0.119 to 0.606. The strength of the social bond between former opponents had no significant effect on grooming occurrence and agonistic behavior after postconflict mounts. Overall, our findings suggest that nonreproductive mounts in Barbary macaques have different functions that are not affected by the strength of the social bond.

Infant handling enhances social bonds in free-ranging rhesus macaques (Macaca mulatta)

Behaviour ◽  
2017 ◽  
Vol 154 (7-8) ◽  
pp. 875-907 ◽  
Author(s):  
Erica S. Dunayer ◽  
Carol M. Berman
Keyword(s):  
Macaca Mulatta ◽  
Social Bonds ◽  
Rhesus Macaques ◽  
Social Characteristics ◽  
Future Research ◽  
Fitness Effects ◽  
Early Handling ◽  
Infant Handling ◽  
Free Ranging ◽  
The Relationship

Throughout the primate order, individuals are highly motivated to handle infants that are not their own. Given the differing and often conflicting interests of the various participants in handling interactions (handler, infant, and mother), most functional hypotheses are specific to particular handling roles. Here we explore one hypothesis that may apply to all participants, but that has received relatively little attention: that handling may facilitate the formation and maintenance of social bonds. Using free-ranging rhesus macaques (Macaca mulatta) on Cayo Santiago, we examine the relationship between infant handling in the early weeks and the strength and diversity of infant social bonds months later, when infant relationships were more independent from those of their mothers. Our results largely confirm the influence of several social characteristics (kinship, rank, sex, and age) in governing handling interactions. They also provide the first evidence that early handling is associated with later social bonds that are stronger than expected based on these social characteristics. However, the enhancement of bonds is largely confined to related handlers; frequent unrelated handlers did not generally go on to form strong bonds with infants. This suggests that kinship may be a sort of prerequisite to the enhancement of social bonds via handling. Given the adaptive benefits of strong social bonds among adult primates, future research should investigate whether early infant handling may have longer term fitness effects.

scholarly journals On estimating the age composition of the commercial catch of Northeast Arctic cod from a sample of clusters

2003 ◽  
Vol 60 (2) ◽  
pp. 297-303 ◽  
Author(s):  
Aanes Sondre ◽  
Michael Pennington
Keyword(s):  
Age Structure ◽  
Age Distribution ◽  
Significant Loss ◽  
Effective Sample Size ◽  
Commercial Fishing ◽  
Total Catch ◽  
Intracluster Correlation ◽  
Age Composition ◽  
Commercial Catch ◽  
Arctic Cod

Abstract Assessment of Northeast Arctic cod is based on estimates of the commercial catch in numbers at age. The age structure of the catch is estimated by sampling fish from commercial fishing trips. Although it is commonly assumed that a sample of individuals is a random sample from the population, fish sampled from the same trip (i.e. from a “cluster” of fish) tend to be more similar in age than those in the total catch. For Northeast Arctic cod, the intracluster correlation for age is positive, and therefore the effective sample size is much smaller than the number of fish aged. Given the number of fish aged, the precision of the estimated age distribution is rather low, and the number of fish aged from each trip could be reduced from approximately 85 to 20 without a significant loss in precision.

Social Well-Being of the Population of Russia During the Pandemic (Based on Sample Survey Data)

2021 ◽  
Vol 28 (4) ◽  
pp. 67-79
Author(s):  
L. A. Davletshina ◽  
N. A. Sadovnikova ◽  
A. V. Bezrukov ◽  
O. G. Lebedinskaya
Keyword(s):  
Health Status ◽  
Population Health ◽  
Age Distribution ◽  
Age Groups ◽  
Rank Correlation ◽  
Well Being ◽  
Russian Population ◽  
Sample Survey ◽  
The Social ◽  
The Relationship

The article present results of the authors’ study of the social well-being of the Russian population – an assessment of the population’s health and attitudes towards a healthy lifestyle amid viral pandemic, based on materials of the Rosstat sample surveys of 2019 and 2020 and data from the All-Russian survey conducted by the Russian Public Opinion Research Center (VCIOM) on 27 September 2020. The authors described the transformation of living conditions in the light of the complex epidemiological situation and the increase in coronavirus cases among the population. Changes in the health status of the Russian population were analyzed by individual age groups.The article assesses the strength of the relationship between the social well-being of the population by selected socio-demographic groups and the period of self-isolation, quarantine, or other restrictions imposed during the coronavirus pandemic in 2020. To solve this problem, demographic and socio-economic characteristics of respondents are presented, the distribution of responses according to the survey results is estimated, and the most signifcant factor characteristics are selected. Respondent replies were grouped according to the selected questions, including in the territorial context (by federal districts). To determine the strength of the relationship between the respondents' answers to the question and their gender or age distribution, the coefcients of mutual conjugacy and rank correlation coefcients were calculated and analyzed.Analysis of the changes in the social well-being of population for 2019–2020 and the assessment of the strength of the relationship between the discussed indicators (gender, wealth, territory of residence) revealed the parameters that form the differences. After comparing the health status of the Russian population as a whole and by age groups in 2019 and 2020 based on data of sample survey on population health status, the following points were identifed. With the expected assessment of the population health status in the age distribution (deterioration in the older ages and better health in the younger ones), it also remains unchanged that more than half of the respondents characterize their health status as «very good» and «good». Noteworthy is the fact that the assessment of the health status of the Russian population has improved during the year. It is evidenced from changes in the structure of respondent replies, even though population health status survey of 2020 was conducted in the middle of lockdown amid the continuing negative trends in coronavirus morbidity and mortality.

Reproductive senescence in free-ranging North American elk Cervus elaphus Cervidae

Mammalia ◽  
2019 ◽  
Vol 83 (6) ◽  
pp. 593-600 ◽  
Author(s):  
Louis C. Bender ◽  
Jessica R. Piasecke
Keyword(s):  
Age Structure ◽  
Cervus Elaphus ◽  
North American ◽  
Reproductive Senescence ◽  
Female Age ◽  
North American Elk ◽  
Age Related ◽  
Consistent Manner ◽  
Multiple Species ◽  
Free Ranging

Abstract Successful production of calves is necessary for growth of North American elk (Cervus elaphus Linnaeus 1758) populations, but few studies have evaluated age-related effects on both the conception and survival of a calf to weaning in multiple free-ranging populations. Conception and survival of calves to weaning were both affected by maternal age, with old (age 9 and older) females showing reproductive senescence as compared to prime-aged (ages 2–8) females despite achieving similar or greater size and condition. Reproductive senescence in our free-ranging populations ultimately resulted in old females weaning fewer calves (0.42 calves/female) than did prime-aged females (0.64 calves/female). Other factors, especially maternal size, also influenced conception and survival to weaning, and these interacted with age in a consistent manner, i.e. larger females or females in better condition were more likely to conceive and successfully wean calves within each age class. Female age structure receives less consideration in ungulate management than does male age structure, despite demonstrated impacts on population productivity of multiple species because of reproductive senescence. Because of the large proportion of individuals in senesced age classes in elk populations, low productivity in populations may simply reflect female age structure, rather than other frequently hypothesized factors.

scholarly journals Tracking Pandemic Severity Using Data on the Age Structure of Mortality: Lessons From the 1918 Influenza Pandemic in Michigan

2021 ◽  
Vol 111 (S2) ◽  
pp. S149-S155
Author(s):  
Siddharth Chandra ◽  
Julia Christensen
Keyword(s):  
Public Health ◽  
Age Structure ◽  
Goodness Of Fit ◽  
Influenza Pandemic ◽  
Age Distribution ◽  
Test Statistic ◽  
Goodness Of Fit Test ◽  
1918 Influenza ◽  
Death Data ◽  
Excess Deaths

Objectives. To test whether distortions in the age structure of mortality during the 1918 influenza pandemic in Michigan tracked the severity of the pandemic. Methods. We calculated monthly excess deaths during the period of 1918 to 1920 by using monthly data on all-cause deaths for the period of 1912 to 1920 in Michigan. Next, we measured distortions in the age distribution of deaths by using the Kuiper goodness-of-fit test statistic comparing the monthly distribution of deaths by age in 1918 to 1920 with the baseline distribution for the corresponding month for 1912 to 1917. Results. Monthly distortions in the age distribution of deaths were correlated with excess deaths for the period of 1918 to 1920 in Michigan (r = 0.83; P < .001). Conclusions. Distortions in the age distribution of deaths tracked variations in the severity of the 1918 influenza pandemic. Public Health Implications. It may be possible to track the severity of pandemic activity with age-at-death data by identifying distortions in the age distribution of deaths. Public health authorities should explore the application of this approach to tracking the COVID-19 pandemic in the absence of complete data coverage or accurate cause-of-death data.

scholarly journals Utility of Red Tide (Karenia brevis) Monitoring Data as a Predictive Tool to Estimate Brevetoxin Accumulation in Live, Free-Ranging Marine Mammals

2021 ◽  
Vol 8 ◽  
Author(s):  
Spencer E. Fire ◽  
Glenn A. Miller ◽  
Edna R. Sabater ◽  
Randall S. Wells
Keyword(s):  
Bottlenose Dolphins ◽  
Karenia Brevis ◽  
Alternative Methods ◽  
Health Impacts ◽  
Sample Type ◽  
Red Tides ◽  
Predictive Tool ◽  
Cell Abundance ◽  
Free Ranging ◽  
The Relationship

Exposure of common bottlenose dolphins (Tursiops truncatus) to brevetoxins (PbTx) produced by blooms of the toxic phytoplankton Karenia brevis frequently results in severe health impacts, including illness and large-scale mortality events. Although PbTx accumulation in dead-stranded dolphins is well documented, there are limited data for corresponding brevetoxin exposure in live dolphins. In addition, the severity of impacts on living survivors of such toxic blooms is difficult to assess due to a lack of data on the relationship between K. brevis bloom severity and corresponding PbTx concentrations in exposed animals. Here we present results of PbTx analysis of urine, serum, milk, gastric fluid, and feces samples collected from live, free-ranging dolphins (n = 253) from Sarasota Bay, Florida during 2000–2018, and investigate the relationship between PbTx concentrations detected and corresponding K. brevis cell abundances that are temporally (within 30 days) and spatially (within 16 km) associated with each individual. We found that 28% of dolphins were associated with elevated K. brevis abundances (10,000–60,000,000 cells/L), with 41% (n = 104) of dolphins testing positive for PbTx in at least one sample type. The proportion of PbTx-positive animals was significantly greater in animals exposed to elevated cell abundances vs. those exposed to background cell abundances (&lt;10,000 cells/L), with 60 and 34% testing positive, respectively (p &lt; 0.001). PbTx was detected most frequently in feces (57%, n = 38), followed by gastric (35%, n = 37), urine (32%, n = 55), and blood (7%, n = 17). PbTx concentrations by sample type were highest in feces (2–231 ng/g; mean 46), followed by urine (0.8–90 ng/g; mean 7.2), gastric (0.8–61 ng/g; mean 12), and blood (0.3–5 ng/g; mean 1.3). Regression analyses of K. brevis cell abundance as an index of exposure vs. corresponding PbTx concentration found no statistically significant relationship for feces (p = 0.120), gastric (p = 0.349), urine (p = 0.053), or blood (p = 0.729) samples. PbTx concentrations typically ranged over two orders of magnitude between minimum and maximum values and did not scale with corresponding indices of exposure, which ranged over three orders of magnitude or more. Our results indicate that K. brevis cell abundance alone is a poor predictor of brevetoxin accumulation in bottlenose dolphins, and suggest that alternative methods (e.g., endocrine or immunological biomarkers) should be investigated as more appropriate methods for determining the severity of health impacts due to red tides.

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