Body Size, Genome Size, and Intrinsic Rate of Increase in Ciliated Protozoa

1981 ◽  
Vol 118 (2) ◽  
pp. 160-172 ◽  
Author(s):  
William D. Taylor ◽  
Brian J. Shuter
Keyword(s):  
Body Size ◽  
Genome Size ◽  
Intrinsic Rate ◽  
Intrinsic Rate Of Increase ◽  
Ciliated Protozoa ◽  
Rate Of Increase

The population and community ecology of invading insects

1986 ◽  
Vol 314 (1167) ◽  
pp. 607-617 ◽  
Keyword(s):  
Body Size ◽  
Empirical Studies ◽  
Intrinsic Rate ◽  
Invasion Success ◽  
Intrinsic Rate Of Increase ◽  
Population Fluctuations ◽  
Main Determinant ◽  
Rate Of Increase ◽  
Cause Of Failure ◽  
Main Determinants

Theory is equivocal about invasion success, implicating various combinations of r , a population’s intrinsic rate of increase, K , its ‘carrying capacity’, enemy-imposed death rates and the coefficient of variation in population numbers as determinants of establishment. Data for a wide variety of organisms, both vertebrates and invertebrates (including insects), accidentally or deliberately introduced by man into the British Isles, appear to show that the probability of establishment of an invader is positively correlated with body size. These data are consistent with the idea that the amplitude of population fluctuations is the main determinant of invasion success, but not with theoretically expected effects of r or K (because populations of small organisms generally fluctuate more than populations of large organisms, but both r and K decrease with increasing body size). However, data for various insect orders introduced into Britain show exactly the opposite trend, with probability of establishment decreasing with increasing body size, and hence possibly with decreasing r and/or K . Possible reasons for these contradictory results, including biases in the data, are discussed. Finally, data from a variety of sources, including insects released as biological control agents, show that enemies (parasitoids and predators) are often a cause of failure to establish particular species of introduced insects. These data add further to the uncertainty about the main determinants of invasion ability. The only clear conclusion to emerge from a combination of theoretical and empirical studies is that r alone is not obviously the main, or even an important determinant of invasion success.

Fertility control of mammal pests and the conservation of endangered marsupials

1997 ◽  
Vol 9 (1) ◽  
pp. 1 ◽  
Author(s):  
A. R. E. Sinclair
Keyword(s):  
Body Size ◽  
Intrinsic Rate ◽  
Fertility Control ◽  
Adult Survival ◽  
Intrinsic Rate Of Increase ◽  
Published Data ◽  
Birth Rates ◽  
Trade Offs ◽  
Rate Of Increase ◽  
Average Size

Populations are bounded by negative feedbacks operating through fertility or mortality, termedpopulation regulation. If fertility is artificially reduced, the average size of the population is also reduced, but only under certain conditions. If (i) juvenile survival or (ii) adult survival improve due to lower fertility, or (iii) territoriality limits populations, the effects of lower birth rate will not change population size unless such reduction exceeds the effects of these processes. Published data on population trends and birth rates have allowed a comparison among species of instantaneous rates of change. The intrinsic rate of increase, rm, and population variability are both related to body size, because birth rates and survivorship are also related to body size. These rates are trade-offs as adaptations. Populations of species in exotic habitats may fluctuate more than when they are in their indigenous habitats. Fertility control could reduce such fluctations. Marsupials have lower birth rates than eutherians, and so rely more on survivorship, perhaps as an adaptation to unpredictable environments. Compromising survival by either habitat change or increased predation will affect marsupials more than eutherians. This explains why many marsupial populations are declining towards extinction.

Influence of temperature on the development and reproduction of Cinara cedri (Hemiptera: Aphidoidea: Lachninae)

2021 ◽  
pp. 1-6
Author(s):  
Yingchao Ji ◽  
Guohua Li ◽  
Chenggang Zhou ◽  
Shuyan Yin
Keyword(s):  
Intrinsic Rate ◽  
Intrinsic Rate Of Increase ◽  
Threshold Temperature ◽  
Reproduction Rate ◽  
Cedrus Deodara ◽  
Developmental Threshold ◽  
Factors Affecting ◽  
Rate Of Increase ◽  
Influence Of Temperature On ◽  
Development Duration

Abstract Temperature is one of the main factors affecting insect growth, development and reproduction. The effects of temperatures (10, 15, 20, 25 and 30°C) on the development and reproduction of Cinara cedri Mimeur (Hemiptera: Aphidoidea: Lachnidae) fed on Cedrus deodara (Roxb.) G. Don were evaluated in this study. With the increase of temperature from 10 to 30°C, the development duration at different development stages gradually shortened. There was a significant positive correlation between the developmental rates and temperature, following a quadratic regression model. The lower developmental threshold temperature (C) and effective accumulated temperatures (K) for completing a generation were 4.13°C and 263.4 degree-days, respectively. The highest fecundity was observed at 20°C with 25.74 first-instar nymphs/female. Both the highest intrinsic rate of increase (r, 0.11 ± 0.03) and net reproduction rate (R0, 19.06 ± 2.05) were observed at 20°C, whereas the lowest values of r (0.05 ± 0.01) at 10°C and R0 (5.78 ± 0.88) at 30°C were observed. The results suggest that temperature significantly affects the biology of C. cedri and the optimal temperature for its development is 20°C.

Ambient Humidity Affects Development, Survival, and Reproduction of the Invasive Fall Armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae), in China

2021 ◽  
Author(s):  
Limei He ◽  
Shengyuan Zhao ◽  
Abid Ali ◽  
Shishuai Ge ◽  
Kongming Wu
Keyword(s):  
Spodoptera Frugiperda ◽  
Fall Armyworm ◽  
Intrinsic Rate ◽  
Intrinsic Rate Of Increase ◽  
Reproduction Rate ◽  
Ambient Humidity ◽  
Rate Of Increase ◽  
Population Forecasting ◽  
Survival And Reproduction ◽  
Net Reproduction

Abstract Ambient humidity can directly affect the water balance in insects. The migratory fall armyworm, Spodoptera frugiperda Smith, has spread to more than 60 countries and regions in Africa, Asia, and Oceania that have a great difference in average ambient humidity. Understanding the effects of ambient humidity changes on its development, survival, and reproduction can help to predict its population dynamics in different habitats. Therefore, we evaluated the effects of atmospheric relative humidity (RH) on the development, survival, and reproduction and soil moisture on the pupation and emergence of fall armyworm. As a result, survival and pupal mass increased significantly with increasing RH. Among the five RHs tested, 80% RH was the most suitable for fall armyworm with the highest intrinsic rate of increase (r), finite rate of increase (λ), and net reproduction rate (R0). The population growth at the different RHs in decreasing order was 80 > 100 > 60 > 40 > 20%. A relative moisture (RM) of soil from 6.80 to 47.59% was suitable for fall armyworm pupation, survival, and eclosion, but fall armyworm could not pupate normally in soil with 88.39 and 95.19% RM. The survival and emergence rate of fall armyworm pupae were reduced by irrigation that increased the RM after the mature larvae entered the soil. These findings may be helpful for refining laboratory rearing protocols, population forecasting, and management of fall armyworm.

scholarly journals Repeated stress exposure results in a survival–reproduction trade-off in Drosophila melanogaster

2009 ◽  
Vol 277 (1683) ◽  
pp. 963-969 ◽  
Author(s):  
Katie E. Marshall ◽  
Brent J. Sinclair
Keyword(s):  
Drosophila Melanogaster ◽  
Model Organism ◽  
Intrinsic Rate ◽  
Intrinsic Rate Of Increase ◽  
Stress Exposure ◽  
Trade Off ◽  
Repeated Stress ◽  
Rate Of Increase ◽  
In The Wild ◽  
Future Reproduction

While insect cold tolerance has been well studied, the vast majority of work has focused on the effects of a single cold exposure. However, many abiotic environmental stresses, including temperature, fluctuate within an organism's lifespan. Given that organisms may trade-off survival at the cost of future reproduction, we investigated the effects of multiple cold exposures on survival and fertility in the model organism Drosophila melanogaster . We found that multiple cold exposures significantly decreased mortality compared with the same length of exposure in a single sustained bout, but significantly decreased fecundity (as measured by r , the intrinsic rate of increase) as well, owing to a shift in sex ratio. This change was reflected in a long-term decrease in glycogen stores in multiply exposed flies, while a brief effect on triglyceride stores was observed, suggesting flies are reallocating energy stores. Given that many environments are not static, this trade-off indicates that investigating the effects of repeated stress exposure is important for understanding and predicting physiological responses in the wild.

scholarly journals Life history of Neoseiulus californicus (McGregor, 1954) (Acari: Phytoseiidae) fed with castor bean (Ricinus communisL.) pollen in laboratory conditions

2014 ◽  
Vol 74 (3) ◽  
pp. 691-697 ◽  
Author(s):  
PP Marafeli ◽  
PR Reis ◽  
EC. da Silveira ◽  
GC Souza-Pimentel ◽  
MA. de Toledo
Keyword(s):  
Life History ◽  
Castor Bean ◽  
Ricinus Communis ◽  
Intrinsic Rate ◽  
Predatory Mite ◽  
Neoseiulus Californicus ◽  
Intrinsic Rate Of Increase ◽  
Ricinus Communis L ◽  
Rate Of Increase ◽  
History Of

The predatory mite, Neoseiulus californicus(McGregor, 1954) (Acari: Phytoseiidae) is one of the principal natural enemies of tetranychid mites in several countries, promoting efficient control of those mites in several food and ornamental crops. Pest attacks such as that of the spider mite, Tetranychus urticaeKoch, 1836 (Acari: Tetranychidae), is one of the problems faced by farmers, especially in the greenhouse, due to the difficulty of its control with the use of chemicals because of the development of fast resistance making it hard to control it. The objective of this work was to study the life history of the predatory mite N. californicus as a contribution to its mass laboratory rearing, having castor bean plant [Ricinus communis L. (Euphorbiaceae)] pollen as food, for its subsequent use as a natural enemy of T. urticae on a cultivation of greenhouse rosebushes. The studies were carried out in the laboratory, at 25 ± 2°C of temperature, 70 ± 10% RH and a 14 hour photophase. The biological aspects and the fertility life table were appraised. Longevity of 32.9 days was verified for adult females and 40.4 days for males. The intrinsic rate of increase (rm) was 0.2 and the mean generation time (T) was 17.2 days. The population doubled every 4.1 days. The results obtained were similar to those in which the predatory mite N. californicus fed on T. urticae.

Reproductive Uncertainty and the Evolution of Iteroparity: Why Don't Flatfish Put All Their Eggs in One Basket?

1981 ◽  
Vol 38 (8) ◽  
pp. 968-977 ◽  
Author(s):  
Derek A. Roff
Keyword(s):  
Reproductive Success ◽  
Life Span ◽  
Intrinsic Rate ◽  
Intrinsic Rate Of Increase ◽  
Rate Of Increase ◽  
Age Of Maturity ◽  
Reproductive Life ◽  
Reproductive Life Span ◽  
Engraulis Ringens ◽  
Using Data

Murphy's hypothesis that variation in reproductive life span is an adaptive response to variation in the predictability of reproductive success is examined. Murphy's contention that this hypothesis explains the variation in reproductive life span within the clupeids is reexamined incorporating further data on the Peruvian anchovy (Engraulis ringens). A nonsignificant correlation is now obtained between reproductive life span and brood strength variation; thus, the hypothesis is called into question. An alternative explanation is presented that considers the interaction between life history parameters: because it is necessary for the intrinsic rate of increase to exceed zero, variation in one parameter must be associated with variation in at least one other parameter. In the clupeids it is noted that the age of maturity and reproductive life span vary in concert and it is suggested that this provides an explanation of variation in reproductive life span. These two hypotheses are examined using data on the family Pleuronectidae, the flatfish. No correlation exists between reproductive life span and the degree of fluctuation in brood strength but there is a significant correlation between reproductive life span and age of maturity. It is concluded that variation in reproductive life span within the flatfish group is not a response to variation in reproductive success but rather a correlate of variation in age of maturity.Key words: flatfish, Pleuronectidae, iteroparity, natural selection, reproduction, clupeids

scholarly journals Biology and life-table of Typhlodromus (Anthoseius) athenas (Acari: Phytoseiidae) fed with the Old World Date Mite, Oligonychus afrasiaticus (Acari: Tetranychidae)

Acarologia ◽  
2018 ◽  
Vol 58 (1) ◽  
pp. 52-61
Author(s):  
Samah Ben Chaaban ◽  
Brahim Chermiti ◽  
Serge Kreiter
Keyword(s):  
Life Table ◽  
Intrinsic Rate ◽  
Phoenix Dactylifera ◽  
Reproductive Rate ◽  
Intrinsic Rate Of Increase ◽  
Net Reproductive Rate ◽  
Old World ◽  
Rate Of Increase ◽  
Wide Range ◽  
The Mean

The old world date mite Oligonychus afrasiaticus is an important spider mite pest of the date palms Phoenix dactylifera L. mostly in North Africa and the Middle East. A population of the predaceous mite Typhlodromus (Anthoseius) athenas has been recently found in Tunisia in association with a decrease of O. afrasiaticus densities. The objective of this paper was to assess the development and reproduction abilities of T. ( A.) athenas on O. afrasiaticus under laboratory conditions at two temperatures: 27 and 32 °C. The results obtained show that females of T. (A.) athenas develop in 5 days at 27 °C and 4.1 days at 32 °C. The mean fecundity of T. (A.) athenas was 32.1 and 23.2 eggs per female at 27 and 32 °C, respectively. Life table parameters were stimated: the net reproductive rate (Ro) 27.9 and 17.9 eggs/female, the intrinsic rate of increase (rm) 0.322 and 0,344 female/female/day and the mean generation time (T) 10.3 and 8.4 days at 27 and 32 °C, respectively. At both temperatures tested, T. (A.) athenas intrinsic rate of increase was greater than that of O. afrasiaticus (rm = 0.213 at 32 °C,against rm = 0.166 day1 at 27 °C). Typhlodromus (A.) athenas would be able to develop at a wide range of temperatures feeding on O. afrasiaticus and seems to be able to potentially control it.

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