scholarly journals Spatiotemporal variation in the adult sex ratio, male aggregation, and movement of two tropical cloud forest dung beetles

2021 ◽  
Author(s):  
Julliana Barretto ◽  
Martha L Baena ◽  
Israel Huesca Domínguez ◽  
Federico Escobar
Keyword(s):  
Life History ◽  
Sex Ratio ◽  
Life History Traits ◽  
Cloud Forest ◽  
Habitat Preferences ◽  
Habitat Type ◽  
Dung Beetle ◽  
Adult Sex Ratio ◽  
The Face ◽  
Male Aggregation

Abstract While theory suggests that at conception the sex ratio should be balanced (1:1), this can be variable across space and time in wild populations. Currently, studies of the environmental factors that regulate adult sex ratio (ASR) in species with different life-history traits are scarce. Using capture-recapture over a year, we analyzed the influence of habitat type (forest and non-forest) and season (rainy and dry) on variation in ASR, male aggregation and the trajectory movement of two dung beetle species with different life-history traits: Deltochilum mexicanum (a hornless roller species) and Dichotomius satanas (a tunneler species with horns on its head and thorax). We found opposite tendencies. The D. mexicanum population tends to be female-biased, but the population of D. satanas tends to be predominantly male, and observed values were not related to habitat type or season. However, the 95% confidence intervals estimated were highly variable between seasons depending on habitat. On examining the monthly variation in ASR for both habitats, we found that it depends on the species. In addition, male aggregation differed between species depending on habitat type and season, and species movement patterns were closely related to their habitat preferences. Based on our results, we argue that comparative population studies of species with different life-history traits are necessary to understand the variation in demographic parameters as well as its ecological and evolutionary implications in the face of spatial and climatic environmental variation.

scholarly journals Causes and consequences of adult sex ratio imbalance in a historical U.S. population

2017 ◽  
Vol 372 (1729) ◽  
pp. 20160314 ◽  
Author(s):  
Ryan Schacht ◽  
Ken R. Smith
Keyword(s):  
Biological Sciences ◽  
Sex Ratio ◽  
Life History Traits ◽  
Male Mating ◽  
Age At First Birth ◽  
The Social ◽  
Adult Sex Ratio ◽  
Sex Ratio Imbalance ◽  
Animal Societies

The responsiveness of individuals to partner availability has been well-documented across the literature. However, there is disagreement regarding the direction of the consequences of sex ratio imbalance. Specifically, does an excess of males or females promote male–male mating competition? In an attempt to clarify the role of the adult sex ratio (ASR) on behaviour, here we evaluate both competing and complimentary expectations derived from theory across the social and biological sciences. We use data drawn from a historical, nineteenth century population in North America and target several life-history traits thought to be affected by partner availability: age at first birth, relationship status, completed fertility and longevity. Furthermore, we assess the role of various contributors to a population's ASR. We find that both the contributors to and consequences of sex ratio imbalance vary over time. Our results largely support predictions of greater male pairbond commitment and lesser male mating effort, as well as elevated bargaining power of women in response to female scarcity. After reviewing our findings, and others from across the literature, we highlight the need to adjust predictions in response to ASR imbalance by the: (i) culturally mediated mating arena, (ii) variable role of demographic inputs across time and place, (iii) constraints to behavioural outcomes across populations, and (iv) ability and accuracy of individuals to assess partner availability. This article is part of the themed issue ‘Adult sex ratios and reproductive strategies: a critical re-examination of sex differences in human and animal societies’.

Life history and feeding biology of the predatory thrips, Aleurodothrips fasciapennis (Thysanoptera: Phlaeothripidae)

1998 ◽  
Vol 88 (3) ◽  
pp. 351-357 ◽  
Author(s):  
D.M. Watson ◽  
T.Y. Du ◽  
M. Li ◽  
J.J. Xiong ◽  
D.G. Liu ◽  
...  
Keyword(s):  
Life History ◽  
Relative Humidity ◽  
Sex Ratio ◽  
Intrinsic Rate ◽  
Natural Increase ◽  
Adult Longevity ◽  
Female Fecundity ◽  
Adult Sex Ratio ◽  
Survival And Reproduction ◽  
Low Humidity

AbstractDetails of the life history, the effects of relative humidity and temperature on survival and reproduction, and the predatory ability of Aleurodothrips fasciapennis Franklin were examined under laboratory conditions. Stage-specific development and adult longevity were similar between sexes, and the adult sex ratio was 1:1. Females laid 23.3 ± 18.0 eggs of which 83% hatched. The survival rate of first instars to adulthood was 82%. The intrinsic rate of natural increase (rm) was 0.04, assuming a zero or 5.4 day pre-oviposition interval. Temperature did not affect the proportion of eggs that hatched, the proportion of first instars surviving to adulthood or adult sex ratios. However, female fecundity was dependent on temperature being highest at 24 ndash 28°C. Relative humidity did not affect adult sex ratio or female fecundity but the proportion of eggs hatched and the survival of first instars to adulthood increased as relative humidity increased. Few eggs hatched when relative humidity was <65%. Larval and adult female A. fasciapennis were voracious feeders but the number of prey killed per progeny was high, suggesting A. fasciapennis was inefficient at converting prey into progeny biomass. The potential value of A. fasciapennis as a biocontrol agent of Aonidiella aurantii (Maskell) on Australian citrus is discussed in terms of its rm, prey killing power and environmental adaptability. It is concluded that population growth of A. fasciapennis should exceed that of A. aurantii under field conditions but A. fasciapennis may be of little value against A. aurantii on citrus grown under conditions of high temperature and low humidity, or when prey densities are low.

scholarly journals Evolution and seed dormancy shape plant genotypic structure through a successional cycle

2021 ◽  
Vol 118 (34) ◽  
pp. e2026212118
Author(s):  
Anurag A. Agrawal ◽  
Amy P. Hastings ◽  
John L. Maron
Keyword(s):  
Genetic Diversity ◽  
Life History ◽  
Environmental Change ◽  
Seed Dormancy ◽  
Life History Traits ◽  
Rapid Evolution ◽  
Insect Herbivory ◽  
Oenothera Biennis ◽  
The Face ◽  
The Impact

Dormancy has repeatedly evolved in plants, animals, and microbes and is hypothesized to facilitate persistence in the face of environmental change. Yet previous experiments have not tracked demography and trait evolution spanning a full successional cycle to ask whether early bouts of natural selection are later reinforced or erased during periods of population dormancy. In addition, it is unclear how well short-term measures of fitness predict long-term genotypic success for species with dormancy. Here, we address these issues using experimental field populations of the plant Oenothera biennis, which evolved over five generations in plots exposed to or protected from insect herbivory. While populations existed above ground, there was rapid evolution of defensive and life-history traits, but populations lost genetic diversity and crashed as succession proceeded. After >5 y of seed dormancy, we triggered germination from the seedbank and genotyped >3,000 colonizers. Resurrected populations showed restored genetic diversity that reduced earlier responses to selection and pushed population phenotypes toward the starting conditions of a decade earlier. Nonetheless, four defense and life-history traits remained differentiated in populations with insect suppression compared with controls. These findings capture key missing elements of evolution during ecological cycles and demonstrate the impact of dormancy on future evolutionary responses to environmental change.

scholarly journals Fecundity of silver-phase eels (Anguilla anguilla) from different habitat types and geographic locations

2015 ◽  
Vol 73 (1) ◽  
pp. 135-141 ◽  
Author(s):  
Ruairí MacNamara ◽  
T. Kieran McCarthy ◽  
Håkan Wickström ◽  
Patrik D. Clevestam
Keyword(s):  
Life History ◽  
Body Size ◽  
Baltic Sea ◽  
Life History Traits ◽  
Geographic Origin ◽  
Habitat Type ◽  
Anguilla Anguilla ◽  
European Eel ◽  
Habitat Types ◽  
Geographic Locations

Abstract The reproductive ecology of European eel (Anguilla anguilla) is poorly understood, though information on life-history traits such as fecundity is necessary for appropriate management of this critically endangered species. During the growth period of the life cycle, yellow-phase eels can be resident in different habitat types (e.g. salinity ranging from freshwater to marine) over a wide geographic distribution. Consequently, maturing silver-phase eels migrating back to the oceanic spawning grounds can display considerable variation in certain life-history traits depending on their habitat and/or geographic origin. Few fecundity estimates are available from wild A. anguilla, and no investigation of the effects of habitat type (i.e. salinity) or geographic location on variation in fecundity has been undertaken. To assess the former, we examined silver-phase eels which had predominantly been resident in freshwater (Lake Mälaren, Sweden) or brackish (Baltic Sea) habitats. Despite Lake Mälaren eels generally being larger, there was no difference in the fecundity–body size relationship between these salinity zones. Second, we determined if fecundity differed between silver-phase eels sampled from different geographic locations: Lake Mälaren and the Baltic Sea outlet in Sweden, the River Shannon in Ireland (northwest Europe) and Vistonis Lake in Greece (eastern Mediterranean). Our results showed that silver-phase eels from Sweden (Lake Mälaren and Baltic Sea outlet) and Greece were significantly more fecund at a given body size than those from Ireland. Spawner models and conservation policies should therefore take account of eel geographic origin in particular when incorporating this life-history parameter.

Reproductive biology of Orchestia gammarellus (Crustacea: Amphipoda) living in a sewage treatment works

1993 ◽  
Vol 73 (2) ◽  
pp. 405-416 ◽  
Author(s):  
M. B. Jones ◽  
G. D. Wigham
Keyword(s):  
Life History ◽  
Sex Ratio ◽  
Embryonic Development ◽  
Body Length ◽  
Life History Traits ◽  
Ovigerous Female ◽  
Seasonal Pattern ◽  
Sewage Treatment ◽  
Female Size ◽  
Egg Volume

A population of the supralittoral Orchestia gammarellus (Pallas) (Amphipoda: Talitridae), living in a percolating filter of a sewage treatment works has been studied over 12 months. The population showed a seasonal pattern of occurrence, few animals being collected during the winter. The sex ratio was biased significantly to females except during the breeding season when it did not deviate significantly from 1:1. Ovigerous females, never collected in high numbers (1–14 per month), were found from April to August, with peak occurrence in May/June. Juveniles were present throughout the year, but peak recruitment occurred in summer, following the period of reproduction by females. The smallest ovigerous female had a body length of 12.6 mm and the largest measured 20.0 mm. Egg numbers (5–31 per brood) increased with increasing female size and egg volume more than doubled during embryonic development. These findings are discussed in relation to the possible methods of colonization of this unique habitat and the influence of sewage on crustacean life-history traits.

Extremely low fecundity and highly female-biased sex ratio in nest-living spider mite Schizotetranychus brevisetosus (Acari: Tetranychidae)

2017 ◽  
Vol 22 (2) ◽  
pp. 170 ◽  
Author(s):  
Kaori Tamura ◽  
Katsura Ito
Keyword(s):  
Life History ◽  
Sex Ratio ◽  
Life Histories ◽  
Life History Traits ◽  
Defense Mechanism ◽  
Intrinsic Rate ◽  
Spider Mites ◽  
Natural Increase ◽  
Blue Oak ◽  
Life Type

Spider mites show various life types characterized by spinning behavior, web structure, and sociality. Individuals of the woven-nest (WN) species construct silken nests on the undersurface of host leaves, inside which they develop and reproduce. This nesting behavior may be related with the defense mechanism and life history traits of mites in the stable habitat (e.g., evergreen trees). If the WN life type affects the life-history traits, these traits may be similar within WN species. The WN species are known to be fragmentarily distributed in diverse genera, Stigmaeopsis, Schizotetranychus, Eotetranychus, and Oligonychus, and their life types are suspected to have secondarily converged. However, their life histories have not been elucidated except for several species in specific genera. To supply the information in Schizotetranychus, we investigated the demographic traits and the sex ratio of Schizotetranychus brevisetosus, which shows the WN life type and lives on the evergreen Japanese blue oak Quercus glauca. We estimated the development time of females as 22.6 ± 3.1 days (mean ± SD, n = 22) and the fecundity of fertilized females as 13.7 ± 5.9 (n = 37) at 25°C. The sex ratio of males to the total number of adults at emergence was low (0.072). The intrinsic rate of natural increase (rm) was estimated as 0.060 day-1, one of the lowest ever reported for spider mites at the same temperature. The present results were similar to other WN species in that fecundity and male ratio were low. 

scholarly journals Higher evolutionary rates in life-history traits in insular than in mainland palms

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Cibele Cássia-Silva ◽  
Cíntia G. Freitas ◽  
Larissa Pereira Lemes ◽  
Gustavo Brant Paterno ◽  
Priscila A. Dias ◽  
...  
Keyword(s):  
Life History ◽  
Adaptive Radiation ◽  
Life History Traits ◽  
Fruit Size ◽  
Habitat Type ◽  
Taxonomic Diversity ◽  
Evolutionary Rates ◽  
Volcanic Island ◽  
Optimal Value ◽  
Volcanic Islands

AbstractIsolated islands, due to the reduced interspecific competition compared to mainland habitats, present ecological opportunities for colonizing lineages. As a consequence, island lineages may be expected to experience higher rates of trait evolution than mainland lineages. However, island effects on key life-history traits of vascular plants remain underexplored at broad spatiotemporal scales, even for emblematic island clades such as palms. Here, we used phylogenetic comparative methods to evaluate potential differences in size and macroevolutionary patterns of height and fruit diameter among mainland, continental, and volcanic island palms. Further, phylogenetic beta-diversity was used to determine if lineage turnover supported an adaptive radiation scenario on volcanic islands. Volcanic island palms were taller than their continental island and mainland counterparts, whereas continental island palms exhibited smaller fruit size. Height and fruit size of palms evolved under evolutionary constraints towards an optimal value. However, scenarios of adaptive radiation and niche conservatism were not supported for the height and fruit size of volcanic and mainland palm clades, respectively, as expected. Instead, continental island palms exhibited higher evolutionary rates for height and fruit size. Insular palm assemblages (continental and volcanic) are composed of unique lineages. Beyond representing evolutionary sources of new palm lineages, our results demonstrate that insular habitats are important in shaping palm trait diversity. Also, the higher phenotypic evolutionary rates of continental island palms suggest disparate selection pressures on this habitat type, which can be an important driver of trait diversification over time. Taken together, these results stress the importance of insular habitats for conservation of functional, phylogenetic, and taxonomic diversity of palms.

scholarly journals Adult sex ratio bias in snowy plovers is driven by sex-specific early survival: implications for mating systems and population growth

2017 ◽  
Author(s):  
Luke J. Eberhart-Phillips ◽  
Clemens Küpper ◽  
Tom E. X. Miller ◽  
Medardo Cruz-López ◽  
Kathryn H. Maher ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Sexual Selection ◽  
Life History ◽  
Sex Ratio ◽  
Population Biology ◽  
Population Viability ◽  
Adult Sex Ratio ◽  
Sexual Selection Theory ◽  
Snowy Plovers ◽  
Sex Biases

ABSTRACTAdult sex ratio (ASR) is a central concept in population biology and a key factor in sexual selection, yet why do most demographic models ignore sex-biases? Vital rates often vary between the sexes and across life history, but their relative contributions to ASR variation remain poorly understood—an essential step to evaluate sex ratio theories in the wild and inform conservation. Here we combine structured two-sex population models with individual-based mark-recapture data from an intensively monitored polygamous population of snowy plovers. We show that a strongly male-biased ASR is primarily driven by sex-specific survival of juveniles, rather than adults or dependent offspring. This provides empirical support for theories of unbiased sex allocation when sex-differences in survival arise after the period of parental investment. Importantly, a conventional model ignoring sex-biases significantly overestimated population viability. We suggest that sex-specific population models are essential to understand the population dynamics of sexual organisms: reproduction and population growth is most sensitive to perturbations in survival of the limiting sex. Overall, our study suggests that sex-biased early survival may contribute towards mating system evolution and population persistence, with implications for both sexual selection theory and biodiversity conservation.SIGNIFICANCE STATEMENTSex biases are widespread in nature and represent a fundamental component of sexual selection and population biology—but at which point in life history do these biases emerge? Here we report a detailed individual-based demographic analysis of an intensively studied wild bird population to evaluate the origins of sex biases and their consequences on mating strategies and population dynamics. We document a strongly male-biased adult sex ratio, which is consistent with behavioral observations of female-biased polygamy. Notably, sex-biased juvenile, rather than adult survival, contributed most to the adult sex ratio. Sex-biases also strongly influenced population viability, which was significantly overestimated when sex ratio and mating system were ignored. Our study therefore has implications for both sexual selection theory and biodiversity conservation.

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