Adult Sex Ratio in the Parnassius Mnemosyne Butterfly: Effects of Survival, Migration, And weather

2009 ◽  
Vol 55 (3) ◽  
pp. 233-252 ◽  
Author(s):  
Petr Vlasanek ◽  
David Hauck ◽  
Martin Konvicka
Keyword(s):  
Sex Ratio ◽  
Population Size ◽  
Linear Models ◽  
Adult Emergence ◽  
Adult Males ◽  
Effective Population ◽  
Weather Variables ◽  
Animal Populations ◽  
Adult Sex Ratio ◽  
Males And Females

Sex ratio biases in animal populations influence the genetically effective population size, and thus are of interest in conservation. A butterfly group in which many authors report biases towards males is the genusParnassiusLatreille, 1804 (Papilionidae). Using a vulnerable woodland species,P. mnemosyne, we carried out a detailed marking campaign designed to eliminate biases towards individual sexes on marking. We then estimated the numbers of males and females using constrained linear models (CLMs) (Cormack-Jolly-Seber and Jolly-Seber in MARK); compared details of mobility between males and females using the Virtual Migration (VM) model; and built CLMs containing weather variables in order to directly assess weather effects on survival. The estimated population size was 4000 adults, with a male: female sex ratio of 1.5-1.6. Both daily and average catchability were higher for males, while the residence values (i.e., survival) were higher for females. Migration parameters were similar for the sexes, with slightly lower male survival within patches and slightly higher male emigration. CLMs with weather substituted for or added to marking days performed worse than models with mere marking days, and although weather affected the sexes differently, males still retained lower survival. The surplus of adult males in the studied population ofP. mnemosynewas real, not caused by increased male survival or a difference in mobility. Therefore, the bias toward males must appear prior to adult emergence, probably during the larval period.

scholarly journals Estimating adult sex ratios in nature

2017 ◽  
Vol 372 (1729) ◽  
pp. 20160313 ◽  
Author(s):  
Sergio Ancona ◽  
Francisco V. Dénes ◽  
Oliver Krüger ◽  
Tamás Székely ◽  
Steven R. Beissinger
Keyword(s):  
Sex Differences ◽  
Sex Ratio ◽  
Evolutionary Biology ◽  
Adult Population ◽  
Sex Ratios ◽  
Estimation Methods ◽  
Spatial And Temporal Variation ◽  
Animal Populations ◽  
Adult Sex Ratio ◽  
Males And Females

Adult sex ratio (ASR, the proportion of males in the adult population) is a central concept in population and evolutionary biology, and is also emerging as a major factor influencing mate choice, pair bonding and parental cooperation in both human and non-human societies. However, estimating ASR is fraught with difficulties stemming from the effects of spatial and temporal variation in the numbers of males and females, and detection/capture probabilities that differ between the sexes. Here, we critically evaluate methods for estimating ASR in wild animal populations, reviewing how recent statistical advances can be applied to handle some of these challenges. We review methods that directly account for detection differences between the sexes using counts of unmarked individuals (observed, trapped or killed) and counts of marked individuals using mark–recapture models. We review a third class of methods that do not directly sample the number of males and females, but instead estimate the sex ratio indirectly using relationships that emerge from demographic measures, such as survival, age structure, reproduction and assumed dynamics. We recommend that detection-based methods be used for estimating ASR in most situations, and point out that studies are needed that compare different ASR estimation methods and control for sex differences in dispersal. This article is part of the themed issue ‘Adult sex ratios and reproductive decisions: a critical re-examination of sex differences in human and animal societies’.

Population parameters of ringed seals (Phoca hispida Schreber, 1775) in the Svalbard area

1987 ◽  
Vol 65 (4) ◽  
pp. 1021-1027 ◽  
Author(s):  
Christian Lydersen ◽  
Ian Gjertz
Keyword(s):  
Sex Ratio ◽  
Ringed Seal ◽  
Adult Males ◽  
Population Parameters ◽  
Phoca Hispida ◽  
Age Class ◽  
Ringed Seals ◽  
Males And Females ◽  
The Mean ◽  
Sexually Mature

Samples were taken from 284 ringed seals (Phoca hispida) in the Svalbard area during April–July 1981 and March–April 1982. The age of 283 seals was determined by reading annuli in the cementum of the canine teeth. The mean age of the males was 11.3 years, and of the females, 14.9 years. Females were found to be significantly older than males. The mean length of sexually mature ringed seals was 128.9 cm for both sexes. The mean weight of adult males and females was 53.5 and 61.4 kg, respectively. Females were found to be significantly heavier than males. The sex ratio was 47.8% males and 52.2% females. Studies of microscopic sections of testis and epididymis from ringed seal males showed that 63, 75, and 80% of 5-, 6-, and 7-year-old animals, respectively, were sexually mature. The weights of testis and epididymis, diameters of tubuli, and the size of testis all showed a marked increase in the 5-year age-class. Macroscopic sections of ovaries from ringed seal females showed that 20, 60, and 80% of 3-, 4-, and 5-year-old animals, respectively, were sexually mature. The size of the ovaries showed a marked increase in the 5-year age-class. The ovulation rate of ringed seals from Svalbard was calculated to be 0.91.

Contribution of adult sex ratio to trauma and reproductive output in large breeding groups of rhesus macaques (Macaca mulatta)

2021 ◽  
Vol 30 (4) ◽  
pp. 479-492
Author(s):  
J Crast ◽  
MA Bloomsmith ◽  
CM Remillard ◽  
T Meeker
Keyword(s):  
Sex Ratio ◽  
Macaca Mulatta ◽  
Social Dynamics ◽  
Rhesus Macaques ◽  
Well Being ◽  
Primate Research ◽  
Adult Males ◽  
Adult Sex Ratio ◽  
Breeding Groups ◽  
Financial Burdens

Maintaining stable breeding groups of rhesus macaques (Macaca mulatta) can be challenging due to the complex social dynamics and despotic nature of the species. Trauma from aggression is a common problem in rhesus colonies and can cause social disruption, strain veterinary and animal management resources, and potentially affect reproduction. Previous research has shown that increasing the number of non-natal adult males in a breeding group can improve group stability, reduce trauma, and increase reproduction. Here, we used mixed-effects regression models to examine the effects of sex ratio and other factors on trauma and reproduction at the Yerkes National Primate Research Center using a historical dataset made up of four large rhesus groups over an eleven-year period (2003–2013). As expected, sex ratio was a significant predictor for both trauma and reproduction. However, group age since formation was a stronger predictor of trauma frequency and the amount of space available was a slightly better predictor of reproduction than sex ratio or trauma. These results indicate that improving sex ratios can be a viable management strategy to reduce trauma and improve reproduction, particularly when it is difficult to manipulate the group compositions and/or their housing situations. Reducing trauma is a primary goal for rhesus breeding colonies, as it directly impacts the monkeys' health and psychological well-being. Such improvements are necessary for the ethical treatment and care of the animals themselves, but also to reduce financial burdens and maintain a healthy colony for research purposes.

Demography of Eurotestudo hermanni in a mesic area of Central Italy

2007 ◽  
Vol 28 (1) ◽  
pp. 87-95 ◽  
Author(s):  
Valeria Ramacciato ◽  
Massimo Capula ◽  
Anna Loy ◽  
Federica Gentilotti
Keyword(s):  
Sex Ratio ◽  
Central Italy ◽  
Average Density ◽  
High Density ◽  
Environmental Constraints ◽  
Adult Males ◽  
Males And Females ◽  
European Populations

AbstractHermann's tortoise (Eurotestudo hermanni) from a mesic area of Central Italy (Isernia, Molise) was investigated during a two-year period (2003-2004). The population is characterized by a fairly high density when compared to other Italian and European populations, with density ranging from 16.16 individuals/ha in 2003 to 25.08 individuals/ha in 2004 (average density 20.84/ha). The sex ratio was 1:1 both in 2003 and 2004. Females were captured in higher percentages from May to July in both years, while males were most abundant from August to October. These differences can be related to the different needs and behaviour of males and females in the two periods, and to the environmental constraints of the study area. All the marked tortoises were found aged between 10 and 21 years. Adult males and females from the study area were small-sized when compared to those from other Italian and European populations.

scholarly journals Population of Proboscis Monkey (Nasalis lavatus) in Manggar River, Balikpapan City, Indonesia

2021 ◽  
Vol 886 (1) ◽  
pp. 012068
Author(s):  
Ike Mediawati ◽  
Teguh Muslim ◽  
Amir Ma’ruf ◽  
Mukhlisi ◽  
Hery Seputro ◽  
...  
Keyword(s):  
Population Density ◽  
Sex Ratio ◽  
Anthropogenic Activities ◽  
Proboscis Monkey ◽  
Adult Males ◽  
Conservation Area ◽  
Nasalis Larvatus ◽  
Survey Technique ◽  
Males And Females ◽  
Proboscis Monkeys

Abstract A population estimation of proboscis monkeys (Nasalis larvatus) has been conducted in Manggar River, Balikpapan. In this non-conservation area, the anthropogenic activities threaten the proboscis monkey habitat. Boat survey technique was applied along ± 17 km of the river in the morning and evening. The number of proboscis monkeys in the surveyed area was estimated to range from 57 to 69 individuals with estimated population density of 4.75 individuals/Km2. Moreover, the population of this primates was divided into 4 groups and the sex ratio between adult males and females was 1:2.33. The proboscis monkeys were distributed in the middle of the river to the upstream. The highest population was found in the upstream area with less human activities. Conservation efforts in the Manggar River need to be carried out considering the proboscis monkey habitat in the area has been fragmented and isolated. These efforts could involve local economic communities.

Factors Affecting the Distribution of Mallards Wintering in the Mississippi Alluvial Valley

The Auk ◽  
1983 ◽  
Vol 100 (4) ◽  
pp. 932-946 ◽  
Author(s):  
James D. Nichols ◽  
Kenneth J. Reinecke ◽  
James E. Hines
Keyword(s):  
Population Size ◽  
Mississippi Alluvial Valley ◽  
Adult Males ◽  
Alluvial Valley ◽  
Factors Affecting ◽  
Young Males ◽  
Young Females ◽  
Winter Distribution ◽  
Wintering Areas ◽  
Males And Females

Abstract The Mississippi Alluvial Valley (MAV) is the principal wintering area for Mallards (Anas platyrhynchos) in the Mississippi Flyway. Here, we consider it a distinct habitat (sensu Fretwell 1972), i.e. fitness is relatively homogeneous among ducks within the MAV but different from that of ducks in other such habitats. We analyzed recovery distributions of Mallards banded preseason (July-September 1950-1980) to test hypotheses concerning the effects of winter temperatures, precipitation, and population levels on Mallard winter distribution. When two groups of years that comprised extremes of warm and cold winter weather were compared, recovery distributions of all four age and sex classes (adult males and females, young males and females) differed significantly; recoveries were located farther south in cold years. Recovery distributions also differed between wet and dry years in the MAV for all groups except adult males, higher proportions of recoveries of adult females and of young males and females occurring in the MAV during wet winters. Although differences in continental Mallard population size were associated with differences in recovery distributions only of adult males and young females, the proportion of young males and of all young Mallards recovered in the MAV increased during years of low populations. We conclude that temperature, water conditions, and population size affect the habitat suitability of Mallard wintering areas and that Mallards exhibit considerable flexibility in winter distribution associated with these factors.

Sex ratio variation in gastrointestinal nematodes of Svalbard reindeer; density dependence and implications for estimates of species composition

Parasitology ◽  
2004 ◽  
Vol 130 (1) ◽  
pp. 99-107 ◽  
Author(s):  
A. STIEN ◽  
M. DALLIMER ◽  
R. J. IRVINE ◽  
O. HALVORSEN ◽  
R. LANGVATN ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Species Composition ◽  
Density Dependence ◽  
Sex Ratios ◽  
Gastrointestinal Nematodes ◽  
Late Winter ◽  
Adult Males ◽  
Svalbard Reindeer ◽  
Ratio Variation ◽  
Adult Sex Ratio

Estimates of the intensity and abundance of species provide essential data for ecological, evolutionary and epidemiological studies of gastrointestinal nematode communities. These estimates are typically derived from the species composition of adult males when only males have readily scorable species-specific morphological traits. Such estimation assumes that all species in the community have the same adult sex ratio. We evaluated this assumption for the trichostrongyle nematodes Ostertagia gruehneri and Marshallagia marshalli in infracommunities in Svalbard reindeer by identifying to species adult females using a polymerase chain reaction assay. The proportion of males was found to be slightly higher in O. gruehneri than in M. marshalli. Evidence for seasonal variation and density dependence in the adult sex ratio was only found for O. gruehneri. Possible demographic mechanisms for such sex ratio variation are discussed, and stochastic models that generate density-dependent sex ratios proposed. Sex ratio variation caused substantial bias in some male-based estimates of intensity of infection, while substantial and consistent bias in estimates of abundances was only evident in late winter samples. Our results suggest that estimating sex ratios can be particularly important in individual host level studies of nematode species of low abundance.

Adult survival and recruitment and the explanation of an uneven sex ratio in a tortoise population

1990 ◽  
Vol 68 (3) ◽  
pp. 547-555 ◽  
Author(s):  
Adrian Hailey
Keyword(s):  
Population Density ◽  
Sex Ratio ◽  
Adult Survival ◽  
Adult Longevity ◽  
Adult Males ◽  
Northern Greece ◽  
Female Population ◽  
Lower Survival Rate ◽  
Adult Sex Ratio ◽  
Testudo Hermanni

Survival, recruitment, and dynamics of adult Testudo hermanni at Alyki (northern Greece) were studied from 1980 to 1988. Recruitment of adult males was greater than that of females owing to their shorter time to maturity (9 vs. 11 years); recruitment of subadults (6 years old) was equal in males and females. Mean annual survival was slightly greater in males (0.914) than females (0.877), equivalent to mean adult longevity values of 11.6 and 8.1 years, respectively. Excluding tortoises that die before maturity, male and female T. hermanni are mature for about 56 and 42% of their life, respectively. Generation time was roughly twice the age at maturity, and three times the age at which secondary sexual characters develop, a pattern which may apply to other tortoises. The combination of adult survival and recruitment should lead to a stable sex ratio (males/females) of 2.1. The adult sex ratio was higher than this, but decreasing, from4.1 in 1982to3.0 in 1986, with an increase in the female population; the number of males was stable. The observed sex ratio showed a similar decline and a further fall to 2.4 in 1988. The cause of the lower survival rate of females compared with males is proposed to be damage during courtship attempts. The courtship behaviour and related anatomy of T. hermanni are compared with those of T. graeca, a species with even population sex ratios. The level of male-induced female mortality would depend on population density; the increasing number of females during the study follows the approximate halving of population density in 1980.

scholarly journals Breeding Strategies to Optimize Effective Population Size in Low Census Captive Populations: The Case of Gazella cuvieri

Animals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1559
Author(s):  
Candela Ojeda-Marín ◽  
Isabel Cervantes ◽  
Eulalia Moreno ◽  
Félix Goyache ◽  
Juan Pablo Gutiérrez
Keyword(s):  
Genetic Variability ◽  
Population Size ◽  
Effective Population Size ◽  
Significant Loss ◽  
Breeding Systems ◽  
Effective Population ◽  
Evolutionary Pattern ◽  
Animal Populations ◽  
Captive Populations

Small-sized animal populations can undergo significant loss of genetic variability that can lead to their extinction. Therefore, studies on animal breeding have focused on mating systems for minimizing the disappearance of genetic variability. The main objective of this study was to compare, using computer simulations, the performance of different breeding schemes to limit the loss of genetic diversity in small-sized populations. This objective was achieved by monitoring the evolution of the effective population size obtained by 23 strategies throughout 20 generations in two populations of Gazella cuvieri. The scenarios were designed with different assumptions, in both reference subpopulations, regarding: the use of parents coancestry or offspring coancestry, the use of their increases or the coefficients themselves, and the number of males and females involved. Computations were performed using an experimental module of Endog v4.9 developed for this purpose. The results of the study showed that strategies for minimizing the coancestry of the parents were better in the short term; however, these strategies were worse in the long term. Minimizing the average coancestry of the offspring was a better approach in the long term. Nevertheless, in both populations, the best results were obtained when both the coancestry of the parents and the coancestry of the offspring were weighted at 5% each and neither males nor females were assumed to contribute to the next generation. In any case, not all strategies had the same evolutionary pattern throughout generations in both populations. The current results show that neither traditional nor new strategies have any general use. Therefore, it is important to carefully test these strategies before applying them to different populations with different breeding needs under different conditions, such as different generation intervals, and different natural breeding systems such as monogamy or polygyny.

scholarly journals Aspectos sobre a nidificação de Centris analis (Fabricius) (Hymenoptera: Apidae: Centridini)

2018 ◽  
Vol 11 (3) ◽  
pp. 162-165
Author(s):  
David Silva Nogueira ◽  
Arianne Moreira Cavalcante ◽  
Rita Kelly de Oliveira Pontes ◽  
Raquel Pick ◽  
Breno Magalhães Freitas
Keyword(s):  
Sex Ratio ◽  
Adult Emergence ◽  
Parasitism Rate ◽  
Pet Bottles ◽  
Experimental Area ◽  
Trap Nests ◽  
Males And Females ◽  
Biological Aspects ◽  
Rate Of Emergence ◽  
Two Peaks

Resumo. A taxa de emergência de abelhas adultas, a de parasitismo e a razão sexual entre machos e fêmeas foram medidas a partir do monitoramento de abelhas Centris analis (Fabricius) em ninhos armadilha de cartolina preta por um período de 13 meses, entre outubro de 2010 a outubro de 2011, em ambiente urbano de Fortaleza, Ceará. Os ninhos foram vistoriados mensalmente e quando concluídos, foram transferidos para garrafas PET na mesma área experimental até a emergência dos adultos. Foram fundados 45 ninhos, onde emergiram 152 indivíduos. As fêmeas de C. analis (95,66%) preferiram o ninho de diâmetro 5 mm. A taxa de emergência foi de 3,3 abelhas por ninho onde até 10 indivíduos foram registrados por ninho. A razão sexual foi de 1 macho para 1,4 fêmeas. Em fevereiro e setembro houve picos de emergência de abelhas adultas e isso pode estar relacionado com a disponibilidade dos recursos florais. A taxa de parasitismo foi de 3,94%, onde 8 ninhos foram cleptoparasitados com emergência de 15 indivíduos, com representantes de Megachilidae, Chrysididae (Hymenoptera) e Bombyliidae (Diptera). A adição dos dados obtidos nesse estudo em comparação com dados já publicados para C. analis podem ajudar a elucidar aspectos biológicos dessa espécie. Nesting aspects of Centris analis (Fabricius) (Hymenoptera: Apidae: Centridini)Abstract. The rate of emergence of adult bees, the parasitism and sex ratio between males and females were measured by monitoring specimens of Centris analis (Fabricius) in trap nests of black cardboard, for a period of 13 months, from October/2010 to October/2011 in Fortaleza, Ceará State. The nests were monitored monthly and when completed, it was removed to PET bottles in the same experimental area until adult emergence. Were founded 45 nests of which 152 adults emerged. The females of C. analis (95.66 %) preferred the nests with diameter of 5 mm diameter. The emergency rate was 3.3 bees per nest where up to 10 individuals were recorded sharing the same nest. The sex ratio was 1 male to 1.4 females. In February and September there were two peaks of adult bees’ emergence and this may be related with the availability of flowers. The parasitism rate was 3.94%, where 8 nests were parasitized with the emergence of 15 individuals, as Megachilidae, Chrysididae (Hymenoptera) and Bombyliidae (Diptera). The addition of the data obtained in this study along with the already published information on C. analis, may help elucidate biological aspects of this species.

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