Observations on the life history of the scorpion Urodacus abruptus (Scorpionidae), and the analysis of its home sites

1966 ◽  
Vol 14 (3) ◽  
pp. 383 ◽  
Author(s):  
GT Smith
Keyword(s):  
Life History ◽  
Sex Ratio ◽  
Numerical Stabilization ◽  
Adult Sex Ratio ◽  
Discrete Population ◽  
History Of ◽  
Black Mountain ◽  
Selection Of

The life history of the scorpion was worked out for a discrete population on Black Mountain near Canberra, A.C.T. The biology was unusual because of an unexpected longevity and a highly imbalanced adult sex ratio. A clear selection of favoured home sites was demonstrated, but it was also shown that availability of food limited the population before all potential home sites were occupied. A mechanism of numerical stabilization dependent on the regulation of recruitment is discussed.

Population dynamics of Stenothoe valida Dana, 1852 (Amphipoda, Stenothoidae) at Cheongsapo beach of Busan, Republic of Korea

Crustaceana ◽  
2021 ◽  
Vol 94 (4) ◽  
pp. 413-429
Author(s):  
Ye Ji Lee ◽  
Won Gyu Park
Keyword(s):  
Population Dynamics ◽  
Life History ◽  
Sex Ratio ◽  
Brood Size ◽  
Ovigerous Female ◽  
Seasonal Pattern ◽  
Recruitment Rate ◽  
Republic Of Korea ◽  
Female Size ◽  
History Of

Abstract The population dynamics of Stenothoe valida Dana, 1852 were studied at Cheongsapo beach of Busan, Republic of Korea, from March 2019 to March 2020. Sampling was conducted once a month at low tide during spring tides. Specimens were grouped by the cephalic length at 0.025 mm intervals, and classified into four categories: females, ovigerous females, males and juveniles. The sex ratio, defined as females : total males + females, exceeded 0.5 during most of the study period. Brood size was significantly coupled with ovigerous female size. Two to four cohorts appeared at each study period. New cohorts occurred at almost every sampling except in the samples Jun-2, and Nov-2. Life span was estimated at 1-2 months. The juvenile ratio, the ratio of ovigerous females, and the recruitment rate estimated by FiSAT were commonly high in summer and winter. The life history of S. valida was not coupled with water temperature, but had a strong seasonal pattern.

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 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.

Dynamics of an Exploited Population of Lake Whitefish (Coregonus clupeaformis)

1977 ◽  
Vol 34 (7) ◽  
pp. 942-953 ◽  
Author(s):  
Graham Bell ◽  
Paul Handford ◽  
Carl Dietz
Keyword(s):  
Life History ◽  
Sex Ratio ◽  
Age Structure ◽  
Annual Rate ◽  
Multiple Regression Equation ◽  
Coregonus Clupeaformis ◽  
Lake Whitefish ◽  
History Of ◽  
Almost All ◽  
Key Words Population Dynamics

The life history of the exploited lake whitefish (Coregonus clupeaformis) population of Lesser Slave Lake, Alberta, is described. Mean age is high, having increased under continued exploitation during the last 30 yr. A method of estimating the population age structure is described. The apparent annual rate of survival of adult fish has fluctuated markedly, but on average seems to lie in the interval 0.40–0.50; the annual rate of natural survival is estimated to be 0.53. Juveniles survive better than adults. Rate of survival during the 1st yr of life was estimated to be about 0.0002. Maturity was late, the median age at first reproduction being 6–61/2 yr. The regressions of fecundity on age and length are described; length now contributes almost all the attributable variance to maturity and fecundity. The sex ratio fluctuates in time; this is caused by the fluctuations in age structure, since sex ratio varies with age. The relationship between sex ratio and age is used to calculate the relative rates of survival of male and female fish.These data are used to construct a life table and to compute population parameters. It is inferred that the ability of the population to respond to exploitation has been eroded during the last 30 yr. In some respects, the life history of the Lesser Slave Lake stock appears to be unusual.After about 30 yr of large-amplitude oscillation the whitefish population collapsed in 1965. This does not seem to have been caused by chronic overfishing. In the first place, the rate of fishing mortality is no more than moderate. Secondly, a multiple regression equation describing whitefish catch in 48 other Alberta lakes in which there has been no overall decline in catch successfully predicts the observed mean catch at Lesser Slave Lake. The oscillations in catch are claimed to reflect a limit cycle in the abundance of the whitefish, driven by a lagged relationship between a predator (the fishermen) and its prey (the whitefish). Whether or not this cycle was deterministically stable, such behavior will inevitably put the population in risk of extinction during troughs in the cycle. We suggest that current management policies may encourage the destabilization of whitefish populations, and we propose a remedy. Key words: population dynamics, population regulation, life history, exploitation, survival, fecundity, Coregonus clupeaformis

Variability in the life history of Unionicola crassipes, a sponge-associated water mite (Acari: Unionicolidae)

1990 ◽  
Vol 68 (6) ◽  
pp. 1227-1232 ◽  
Author(s):  
Heather C. Proctor ◽  
Gordon Pritchard
Keyword(s):  
Life History ◽  
Sex Ratio ◽  
Emerging Adults ◽  
Life Histories ◽  
Population Decline ◽  
Early Summer ◽  
Water Mites ◽  
Water Mite ◽  
History Of ◽  
Female Bias

The life history of a member of the widely distributed Unionicola crassipes complex (Acari: Unionicolidae) in a foothills pond in Alberta, Canada, differs from those previously described for this taxon. Two years are required for a female to develop from an egg to an ovipositing adult. Fertilized females overwinter and oviposit in the sponge Eunapius fragilis in early May. Larvae emerge in late May to early June and parasitize chironomids of the genus Tanytarsus. Engorged larvae drop from their insect hosts and return to sponges for the protonymph resting stage. Active, predaceous deutonymphs develop from protonymphs in early summer. Deutonymphs overwinter and enter the tritonymph resting stage, also in sponges, in early May. Summer adults emerge from the tritonymph stage in late May to early June. Males emerge first, but there is an overall female bias to the sex ratio of emerging adults. Growth of sclerotized and unsclerotized parts occurs in adults over the summer, during which time females appear to suffer greater mortality than males, because the sex ratio is 1:1 in September. It is primarily mated females that overwinter for a second time. A population decline in the summer of 1987 was correlated with degeneration of sponges; variation in the life histories of sponge-associated water mites is discussed in light of this correlation.

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.

OBSERVATIONS ON LIFE HISTORY AND SEX RATIO VARIABILITY OF EUPTEROMALUS DUBIUS (HYMENOPTERA: PTEROMALIDAE), A PARASITE OF CYCLORRHAPHOUS DIPTERA

1976 ◽  
Vol 108 (11) ◽  
pp. 1267-1274 ◽  
Author(s):  
H.G. Wylie
Keyword(s):  
Life History ◽  
Sex Ratio ◽  
Lower Percentage ◽  
Female Progeny ◽  
History Of ◽  
Ratio Change

AbstractFemales of Eupteromalus dubius (Ashm.) oviposit on pupae of cyclorrhaphous Diptera and the larvae develop gregariously as ectoparasites. Details of the life history of E. dubius are described. A progressively lower percentage of female progeny of E. dubius matures as the parasite:host ratio increases. Three mechanisms that may cause this sex ratio change are examined and discussed.

LIFE HISTORY OF CRICOTOPUS MYRIOPHYLLI OLIVER (DIPTERA: CHIRONOMIDAE) IN THE OKANAGAN VALLEY, BRITISH COLUMBIA

1993 ◽  
Vol 125 (6) ◽  
pp. 979-985 ◽  
Author(s):  
Ian V. MacRae ◽  
Richard A. Ring
Keyword(s):  
British Columbia ◽  
Life History ◽  
Sex Ratio ◽  
Larval Instar ◽  
Field Observations ◽  
Laboratory Rearing ◽  
The Third ◽  
First Instar ◽  
History Of ◽  
Rate Of Emergence

AbstractThe life history of Cricotopus myriophylli Oliver is described from both field observations and laboratory rearing of field-collected larvae. The species appears to be univoltine with four larval instars and has a sex ratio of ca. 2:1, males to females. Emergence begins in late May in British Columbia and continues until mid-September, with first-instar larvae present in the field from mid-June to mid-August. Water temperature does not appear to influence the rate of emergence. In the laboratory at 21 °C, larvae complete each of the third and fourth instars in 10–14 days. Cricotopus myriophylli overwinters primarily in the third larval instar, although second and fourth instars were also recovered in field-collected samples. First-instar larvae and eggs were not recovered from winter samples. This species does not appear to undergo a true diapause.

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