Porcellio spinicornis Say (Isopoda) demography. III. A comparison between field data and the results of a simulation model

1976 ◽  
Vol 54 (12) ◽  
pp. 2174-2184 ◽  
Author(s):  
Donald James McQueen
Keyword(s):  
Population Growth ◽  
Simulation Model ◽  
Field Data ◽  
Survival Rates ◽  
Laboratory Data ◽  
Individual Growth ◽  
Growth And Survival ◽  
Life History Stages ◽  
Demographic Rates ◽  
Rates Of Growth

A simulation model for a Porcellio spinicornis Say population was constructed using laboratory data for rates of growth, reproduction, and survival and using winter survival rates observed in the field. The simulated output was compared with field data collected from 1971 to 1973. The expected and observed weight distributions and reproductive periodicities showed good agreement. The expected and observed patterns of numerical change also agreed for all life-history stages, except 18-month-old individuals, which disappeared from the field counts more quickly than expected. Sensitivity analysis showed that the time at which reproduction began each year was not as critical to population growth as were the effects of minor shifts in temperature on individual growth and survival rates. Furthermore, individual growth rate emerged as the factor having the greatest effect on patterns of population growth. Since the laboratory data on growth was reasonably accurate it is probable that the simulation model adequately describes the processes that determine the changes observed in the field population monitored during this study. All of the evidence indicated that during the period of study the population did not increase or decrease and that temperature conditions modifying demographic rates could have accounted for this observation.

The influence of climatic factors on the demography of the terrestrial isopod Tracheoniscus rathkei Brandt

1976 ◽  
Vol 54 (12) ◽  
pp. 2185-2199 ◽  
Author(s):  
Donald J. McQueen
Keyword(s):  
Life Cycle ◽  
Simulation Model ◽  
Field Data ◽  
Climatic Factors ◽  
Laboratory Data ◽  
Day Length ◽  
Model Output ◽  
Population Limitation ◽  
Growth And Survival ◽  
Rates Of Growth

A field population of the isopod Tracheoniscus rathkei was monitored during 1971, 1972, and 1973. At the same time, laboratory data related to growth, reproduction, and survival were collected and combined to produce a simulation model. The model output was compared with the field data. In the laboratory, T. rathkei required humidities very near 100% relative humidity, day length had no effect on growth rates, and temperature altered rates of growth and survival and determined the periodicity of reproduction. In the field, T. rathkei exhibited a 2-year life cycle, breeding occurred in the spring and summer, and about 83% of the population bred once and 42% bred twice during each year. Juveniles grew throughout the fall, overwintered, reproduced at 1 year of age, continued to grow, overwintered a second time, reproduced again, and died. The simulation model mimicked this pattern with considerable precision. Both the field data and the simulated output suggested that the population expanded during 1971, 1972, and 1973. No mechanisms for population limitation were found.

Porcellio spinicornis Say (Isopoda) demography. II. A comparison between field and laboratory data

1976 ◽  
Vol 54 (6) ◽  
pp. 825-842 ◽  
Author(s):  
Donald J. McQueen
Keyword(s):  
Field Data ◽  
Laboratory Data ◽  
Field Population ◽  
Laboratory Studies ◽  
The Third ◽  
Terrestrial Isopod ◽  
Independent Laboratory ◽  
Demographic Study ◽  
June July ◽  
Rates Of Growth

Field data from a demographic study of the terrestrial isopod Porcellio spinicornis Say were analyzed and compared with laboratory data reported by McQueen and Carnio. On the study area, which covered 482.8 m2, it was observed that reproduction began when average temperatures were > 13 °C, and that about 86% of the individuals produced one brood and about 30% produced two broods. During 1972, 25 654 offspring were produced and during 1973, 27 664 offspring resulted from reproduction, which took place during May, June, July, and August. By October of both years, these animals attained sizes ranging from 10 to 30 mg and exhibited 42 to 47% survivorship. During the next summer, females grew to between 30 and 50 mg and males to between 20 and 40 mg, and survivorship ranged from 15% in May to 2% in August. During the third summer, females attained sizes ranging from 80 to 100 mg and males from 40 to 70 mg. Survivorship during this period ranged from 1% in May to 0% in August. All rates of growth, reproduction, and survival, as well as reproductive periodicity, agreed with independent laboratory studies conducted under controlled conditions. During the 3 years studied the field population remained relatively constant and appeared to be limited by temperature conditions.

Influence of growth and survival costs of reproduction on Atlantic cod, Gadus morhua, population growth rate

1999 ◽  
Vol 56 (9) ◽  
pp. 1612-1623 ◽  
Author(s):  
Jeffrey A Hutchings
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Environmental Stochasticity ◽  
Individual Growth ◽  
Growth And Survival ◽  
Individual Growth Rate ◽  
Age Structured ◽  
Reproductive Rates

A stochastic, age-structured life history model was used to examine how age at maturity (theta), pre- (Zimm) and postreproductive (Zmat) mortality, and postreproductive growth rate can affect maximum reproductive rates of fish at low population size. Simulations suggest that annual (r) and per-generation (R0) metrics of population growth for Newfoundland's northern Grand Bank Atlantic cod, Gadus morhua, are primarily influenced by changes to mortality prior to and following reproduction. At observed weights at age and Zmat = 0.2, r ranged between 0.135 and 0.164 for cod maturing at between 4 and 7 years. Incremental increases in either Zimm or Zmat of 0.1 were associated with 0.03-0.05 reductions in r. To effect similar reductions, individual growth rate would have to decline by approximately one half. At observed weights at age, increases in Zmat from 0.20 to 0.45 increased the probability of negative per-generation growth from 3 to 26% for cod maturing at 4 years and from 6 to 46% for cod maturing at 7 years. Thus, even in the absence of fishing mortality, little or no population growth by Atlantic cod may not be unexpected in the presence of environmental stochasticity, particularly when accompanied by increases in mortality and declining individual growth.

A STEPWISE COMPUTER PROGRAM FOR ESTIMATING DEVELOPMENT TIME AND SURVIVAL OF AEDES VEXANS (DIPTERA: CULICIDAE) LARVAE AND PUPAE IN FIELD POPULATIONS IN SOUTHERN ALBERTA

1979 ◽  
Vol 111 (11) ◽  
pp. 1241-1253 ◽  
Author(s):  
J. D. Slater ◽  
G. Pritchard
Keyword(s):  
Computer Program ◽  
Survival Rates ◽  
Laboratory Data ◽  
Pupal Stage ◽  
Stage Larva ◽  
Aedes Vexans ◽  
Growth And Survival ◽  
Larval Stages ◽  
Pupal Mortality ◽  
Better Than

AbstractGrowth and survival rates for larvae and pupae of Aedes vexans (Meigen) were measured in the laboratory at constant temperatures of 10°, 15°, 20°, 25°, and 30 °C. Growth rates in all stages increased with temperature except for 1st stage larvae which developed marginally faster at 25°C than at 30°C. The shortest stage at all temperatures was the 2nd, followed in most cases by the 3rd, 1st, and 4th larval stages, and then pupae; pupae and 4th stage larvae took markedly longer to develop at low temperatures. Average survival rate was about 99% every 3 h for larvae and 98% for pupae. At 10° and 15°C, 1st and 2nd stage larvae survived no better than later stages, but at the higher temperatures survival to the 3rd stage larva was better than 90% but decreased markedly in the 3rd and 4th stages. Overall survival was highest at 25°C. Mosquitoes reared at 10°C did not pupate, while those reared at 30 °C pupated but adults did not emerge.These laboratory data were used in a computer program whose output under field temperature regimes was compared with events in the field. The program works in 3 h time-steps. Rate of development varies with temperature and utilizes a modification of the algorithm of Stinner et al. (1975); the modification removes time as the independent variable in the development equation. Mortality rates are constant at 1% every 3 h for larvae and 2% for pupae. The program’s predictions for graduation from one stage to the next in the field population were all within about 13 h of the observed times and at the start of the pupal stage after 400 h, the output was running 13 h slow. The program appears to run slow at median temperatures below 10 °C and fast at median temperatures above 14°C. Events in the laboratory rearings are offered as possible explanations for these discrepancies. Predicted population size was close to that observed until the late 4th stage larva, from which point it deviated markedly. Pupal mortality in the field was much higher than in the laboratory.

Maintained effects of fire on individual growth and survival rates in a spur-thighed tortoise population

2013 ◽  
Vol 59 (6) ◽  
pp. 911-913 ◽  
Author(s):  
Roberto Carlos Rodríguez-Caro ◽  
Eva Graciá ◽  
José Daniel Anadón ◽  
Andrés Gimenez
Keyword(s):  
Survival Rates ◽  
Individual Growth ◽  
Growth And Survival

scholarly journals Optimized Live Feed Regime Significantly Improves Growth Performance and Survival Rate for Early Life History Stages of Pangasius Catfish (Pangasianodon hypophthalmus)

Fishes ◽  
2020 ◽  
Vol 5 (3) ◽  
pp. 20
Author(s):  
Ngoc-Ut Vu ◽  
Truong-Giang Huynh
Keyword(s):  
Life History ◽  
Survival Rate ◽  
Early Life ◽  
Survival Rates ◽  
Early Life History ◽  
Growth And Survival ◽  
Pangasianodon Hypophthalmus ◽  
Life History Stages ◽  
The Third ◽  
Live Feed

This study aimed to determine the optimal live feed regime (i.e., initial feeding moment, density, and frequency) for maximum growth and survival of pangasius catfish (Pangasianodon hypophthalmus) early life history stages. The first experiment assessed the optimal initial feeding moment (30, 36, 42, and 48 h post hatching, hph). The second experiment assessed feeding density (3, 5, 8 and 11 individuals per mL, ind/mL) at the optimal initial feeding moment (30 hph) which was the best result from the first experiment. The third experiment assessed optimal feeding frequency (1, 2, 4, and 6 times per day) at the optimal initial feeding moment (30 hph) and density (8 ind/mL) which was drawn upon from the second experiment. All experiments were conducted in 20 L containers containing 20 hph P. hypophthalmus larvae at a density of 10 ind/L and fed rotifers (Brachionus angularis) for 3 days and then water fleas (Moina macrocopa) for 7 days. The first experiment demonstrated that larvae initially fed at 30 hph exhibited a significantly higher survival rate (24%) than larvae initially fed at 36, 42, and 48 hph (19%, 16%, and 16%), respectively. The second experiment demonstrated that larvae fed at 8 and 11 ind/mL densities exhibited significantly higher survival rates (32% and 32%) than larvae fed at 3 and 5 ind/mL densities (13% and 23%), respectively. The third experiment demonstrated that the highest survival rate (66%) was obtained when larvae were fed 6 times per day. These results provide valuable insights regarding the optimal live feed regime for better growth and survival of P. hypophthalmus larvae, which are commercially important and numerously cultured throughout the Mekong Delta region.

Community characteristics of forest understory birds along an elevational gradient in the Horn of Africa: A multi-year baseline

The Condor ◽  
2021 ◽  
Author(s):  
Kyle D Kittelberger ◽  
Montague H C Neate-Clegg ◽  
Evan R Buechley ◽  
Çağan Hakkı Şekercioğlu
Keyword(s):  
Species Richness ◽  
Species Turnover ◽  
Survival Rates ◽  
Elevational Gradient ◽  
Forest Understory ◽  
Bird Abundance ◽  
Tropical Mountains ◽  
Demographic Rates ◽  
Understory Birds ◽  
Over Time

Abstract Tropical mountains are global hotspots for birdlife. However, there is a dearth of baseline avifaunal data along elevational gradients, particularly in Africa, limiting our ability to observe and assess changes over time in tropical montane avian communities. In this study, we undertook a multi-year assessment of understory birds along a 1,750 m elevational gradient (1,430–3,186 m) in an Afrotropical moist evergreen montane forest within Ethiopia’s Bale Mountains. Analyzing 6 years of systematic bird-banding data from 5 sites, we describe the patterns of species richness, abundance, community composition, and demographic rates over space and time. We found bimodal patterns in observed and estimated species richness across the elevational gradient (peaking at 1,430 and 2,388 m), although no sites reached asymptotic species richness throughout the study. Species turnover was high across the gradient, though forested sites at mid-elevations resembled each other in species composition. We found significant variation across sites in bird abundance in some of the dietary and habitat guilds. However, we did not find any significant trends in species richness or guild abundances over time. For the majority of analyzed species, capture rates did not change over time and there were no changes in species’ mean elevations. Population growth rates, recruitment rates, and apparent survival rates averaged 1.02, 0.52, and 0.51 respectively, and there were no elevational patterns in demographic rates. This study establishes a multi-year baseline for Afrotropical birds along an elevational gradient in an under-studied international biodiversity hotspot. These data will be critical in assessing the long-term responses of tropical montane birdlife to climate change and habitat degradation.

Inbreeding depression and floral type fitness differences in Viola canadensis (Violaceae), a species with chasmogamous and cleistogamous flowers

2000 ◽  
Vol 78 (11) ◽  
pp. 1420-1429 ◽  
Author(s):  
Theresa M Culley
Keyword(s):  
Inbreeding Depression ◽  
Survival Rates ◽  
Early Life History ◽  
Flower Number ◽  
Life History Stages ◽  
The North ◽  
History Of ◽  
Vegetative Biomass ◽  
Similar Survival ◽  
Cross Type

Few studies of inbreeding depression have focused on species producing both showy, chasmogamous (CH) flowers and self-pollinated, cleistogamous (CL) flowers. The goals of this investigation were to measure the level of inbreeding depression in the North American violet, Viola canadensis L., and to determine if any fitness differences were linked to floral type (CH versus CL) rather than to cross type (self versus outcross). Hand pollinations were carried out to produce self- and outcross-pollinated CH progeny, and CL seeds were also collected. In a greenhouse, selfed and outcrossed CH flowers produced similar numbers of seeds, and both types of progeny had similar survival rates and comparable numbers of CH flowers, although outcrossed CH progeny had 14% greater vegetative biomass than selfed CH progeny. The level of inbreeding depression in V. canadensis was low, indicating that there may be few drawbacks to selfing in this species. A comparison of CL and self-pollinated CH progeny showed that, although there were differences in CH flower number, overall fitness differences were minimal. The similar performance of selfed (CL and CH) and outcrossed progeny in early life-history stages of V. canadensis suggests a history of inbreeding in the population.Key words: cleistogamy, inbreeding depression, outcrossing, selfing, Viola canadensis.

PATTERNS OF GROWTH IN HEIGHT AND WEIGHT FROM BIRTH TO EIGHTEEN YEARS OF AGE

PEDIATRICS ◽  
1959 ◽  
Vol 24 (5) ◽  
pp. 904-921
Author(s):  
Robert B. Reed ◽  
Harold C. Stuart
Keyword(s):  
Growth Curves ◽  
Growth Patterns ◽  
Individual Growth ◽  
Growth Spurt ◽  
Adolescent Growth Spurt ◽  
Wide Range ◽  
Basic Facts ◽  
The Individual ◽  
Rates Of Growth ◽  
Mature Size

In this report is displayed the range of variation observed in the growth curves of height and weight in a series of 134 children observed from birth to 18 years. For purposes of simplification the individuals have been classified on the basis of their rates of growth during three successive 6-year intervals. Even in terms of this crude classification several basic facts about individual growth patterns of height and weight are apparent. The wide range of differences between individuals applies not only to facts about size at specific ages but also to the pattern of change followed from age period to age period. The rate of growth during early childhood, i.e. before 6 years of age, is associated with, but not specifically predictive of, size at maturity and timing of the adolescent growth spurt. Individuals with rapid growth before 6 years of age tend to have large mature size and early adolescent growth spurt. It will be the objective of future reports from this research project to determine the manner in which the individual differences in growth demonstrated and classified here are related to aspects of physical development, to environmental influences such as dietary intake and to the level of health of the child.

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