scholarly journals A novel two-generation approach for understanding the population dynamics of gregarious parasitoids

2021 ◽  
Author(s):  
Alena Samková ◽  
Jan Raška ◽  
Jiří Hadrava ◽  
Jiří Skuhrovec
Keyword(s):  
Population Dynamics ◽  
Body Size ◽  
Clutch Size ◽  
Traditional Approach ◽  
The Body ◽  
Natural Ecosystems ◽  
Individual Fitness ◽  
Novel Approach ◽  
F2 Generation ◽  
F1 Generation

AbstractParasitoids, as important natural enemies, help maintain balance in natural ecosystems. Their population dynamics is generally predicted from the number of individuals. Here, using gregarious parasitoids as models, we show that this traditional approach omits one important parameter: the mother’s manipulation of offspring fertility due to the clutch size–body size– fertility correlation. As a result of this correlation, when females deliberately adjust the number of offspring laid in a host, they determine not only the number but also the body sizes and reproductive potentials of those offspring. For the first time in the model speciesAnaphes flavipes, we determined the parasitoid’s offspring fertility from clutch size. Using this, we experimentally clarified the advantage of specific clutch size combinations and we show that identical fertility in the F1 generation can lead to distinctly different fertility values in the F2 generation. Even with the same number of hosts, lower fertility in the F1 generation can cause higher fertility in the F2 generation. Based on these results, we propose a novel two-generation approach which includes the clutch size–body size–fertility correlation. Our novel approach provides a new perspective for determining the individual fitness levels of gregarious parasitoids with new options for the modelling of parasitoid population dynamics.

scholarly journals The body-size dependence of mutual interference

2014 ◽  
Vol 10 (6) ◽  
pp. 20140261 ◽  
Author(s):  
John P. DeLong
Keyword(s):  
Population Dynamics ◽  
Body Size ◽  
Size Dependence ◽  
Empirical Support ◽  
Mutual Interference ◽  
The Body ◽  
Wide Range ◽  
Stabilizing Effect ◽  
Body Sizes ◽  
Size Scales

The parameters that drive population dynamics typically show a relationship with body size. By contrast, there is no theoretical or empirical support for a body-size dependence of mutual interference, which links foraging rates to consumer density. Here, I develop a model to predict that interference may be positively or negatively related to body size depending on how resource body size scales with consumer body size. Over a wide range of body sizes, however, the model predicts that interference will be body-size independent. This prediction was supported by a new dataset on interference and consumer body size. The stabilizing effect of intermediate interference therefore appears to be roughly constant across size, while the effect of body size on population dynamics is mediated through other parameters.

scholarly journals Linking individual phenotype to density-dependent population growth: the influence of body size on the population dynamics of malaria vectors

2011 ◽  
Vol 278 (1721) ◽  
pp. 3142-3151 ◽  
Author(s):  
Tanya L. Russell ◽  
Dickson W. Lwetoijera ◽  
Bart G. J. Knols ◽  
Willem Takken ◽  
Gerry F. Killeen ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Body Size ◽  
Population Growth ◽  
Vector Control ◽  
Anopheles Gambiae ◽  
Phenotypic Expression ◽  
Phenotypic Traits ◽  
Density Dependent ◽  
Individual Fitness ◽  
The Impact

Understanding the endogenous factors that drive the population dynamics of malaria mosquitoes will facilitate more accurate predictions about vector control effectiveness and our ability to destabilize the growth of either low- or high-density insect populations. We assessed whether variation in phenotypic traits predict the dynamics of Anopheles gambiae sensu lato mosquitoes, the most important vectors of human malaria. Anopheles gambiae dynamics were monitored over a six-month period of seasonal growth and decline. The population exhibited density-dependent feedback, with the carrying capacity being modified by rainfall (97% w AIC c support). The individual phenotypic expression of the maternal ( p = 0.0001) and current ( p = 0.040) body size positively influenced population growth. Our field-based evidence uniquely demonstrates that individual fitness can have population-level impacts and, furthermore, can mitigate the impact of exogenous drivers (e.g. rainfall) in species whose reproduction depends upon it. Once frontline interventions have suppressed mosquito densities, attempts to eliminate malaria with supplementary vector control tools may be attenuated by increased population growth and individual fitness.

scholarly journals Consistent individual differences in the foraging behaviour of forest tent caterpillars (Malacosoma disstria)

2007 ◽  
Vol 85 (11) ◽  
pp. 1117-1124 ◽  
Author(s):  
L. Nemiroff ◽  
E. Despland
Keyword(s):  
Population Dynamics ◽  
Individual Differences ◽  
Foraging Behaviour ◽  
Malacosoma Disstria ◽  
Larval Performance ◽  
Individual Activity ◽  
Individual Fitness ◽  
Novel Approach ◽  
Behavioural Types ◽  
Tent Caterpillars

Outbreaking insects are often considered identical units despite recent work in behavioural ecology that shows repeatable differences can exist between individuals and can have important implications for individual fitness and population processes. However, although entomologists have neglected the hypothesis that differences between individuals can play an important role in the ecology of a species, it is not new. Wellington (1957. Can. J. Zool. 35: 293–323) suggested that consistent individual differences in behaviour may play a role in the population dynamics of Malacosoma (Hübner, 1820) species (Lepidoptera: Lasiocampidae). We used a novel approach to determine if individual larval Malacosoma disstria Hübner, 1820 exhibit distinct and repeatable behavioural traits. Second-instar caterpillars were placed on individual arenas for 1 h on 4 consecutive days, and the proportion of time spent walking, searching, quiescent, and eating was documented. Active and sluggish behavioural types were distinguished and stable differences in individual activity were observed. Activity was positively correlated with growth during the 4 days of the experiment, but no significant relationship was detected between behaviour during the experiment and overall larval performance in the laboratory setting. These findings demonstrate consistent variation in the foraging behaviour of forest tent caterpillars and lay the basis for further investigatison of its role in colony function and population dynamics.

scholarly journals Contrasting size and fate of juvenile crown-of-thorns starfish linked to ontogenetic diet shifts

2020 ◽  
Vol 287 (1931) ◽  
pp. 20201052
Author(s):  
Jennifer C. Wilmes ◽  
Andrew S. Hoey ◽  
Morgan S. Pratchett
Keyword(s):  
Population Dynamics ◽  
Body Size ◽  
Coralline Algae ◽  
Phenotypic Traits ◽  
Diet Shift ◽  
Growth And Survival ◽  
Ontogenetic Diet Shift ◽  
Individual Fitness ◽  
Ontogenetic Diet Shifts ◽  
Diet Shifts

Population dynamics of organisms are shaped by the variation in phenotypic traits, often expressed even among individuals from the same cohort. For example, individual variation in the timing of ontogenetic shifts in diet and/or habitat greatly influences subsequent growth and survival of some organisms, with critical effects on population dynamics. Few studies of natural systems have, however, demonstrated that marked phenotypic variation in growth rates or body size among individuals within a modelled cohort is linked to dietary shifts and food availability. Population irruptions of the crown-of-thorns starfish are one of the foremost contributors to the global degradation of coral reefs, but causes of irruptions have been debated for decades. Here we demonstrate, based on extensive field sampling of juvenile starfish ( n = 3532), that marked variation in body size among juvenile starfish is linked to an ontogenetic diet shift from coralline algae to coral. This transition in diet leads to exponential growth in juveniles and is essential for individuals to reach maturity. Because smaller individuals experience higher mortality and growth is stunted on an algal diet, the ontogenetic shift to corallivory enhances individual fitness and replenishment success. Our findings suggest that the availability of coral prey facilitates early ontogenetic diet shifts and may be fundamental in initiating population irruptions.

scholarly journals Scarcity of hosts for gregarious parasitoids indicates an increase of individual offspring fertility by reducing their own fertility

2021 ◽  
Author(s):  
Alena Samková ◽  
Jan Raška ◽  
Jiří Hadrava ◽  
Jiří Skuhrovec
Keyword(s):  
Body Size ◽  
Reproductive Potential ◽  
Female Offspring ◽  
The Body ◽  
Individual Offspring ◽  
Single Host ◽  
Gregarious Parasitoid ◽  
Lower Mobility ◽  
Lower Fertility ◽  
F2 Generation

ABSTRACTThe gregarious parasitoid strategy allows multiple larvae to complete development in a single host due to their tolerance and/or lower mobility and thus flexibly adjust their reproductive potential amidst changing environmental conditions. Reproductive success is generally measured as the number of each mother’s offspring. We propose that with scarcity of host, for gregarious parasitoids is important the view on the fertility not only of a mother but also of her offspring (F1 generation). Due to the body size-fitness correlation, each female deliberately adjusts the clutch size, determining the offspring body size and their reproductive potential. In our study, using Anaphes flavipes as a model species, we showed that under a limited number of hosts, the females reduced their fertility. We propose that the lower fertility of mothers can cause higher fertility in the F2 generation using a larger offspring body while halving fertility. The females increase their individual offspring’s fertility by reducing their own fertility. Moreover, we showed that with a scarcity of hosts, the mothers increased the number of their female offspring, and thus, they obtained more offspring in the F2 generation. Additionally, other costs and benefits of the gregarious strategy in relation to superparasitism were tested and discussed.

The relationship between maternal body size and clutch size, development time and egg mortality in Euchaeta norvegica (Copepoda: Calanoida) from Loch Etive, Scotland

1977 ◽  
Vol 57 (3) ◽  
pp. 723-733 ◽  
Author(s):  
C. C. E. Hopkins
Keyword(s):  
Body Size ◽  
Clutch Size ◽  
Body Length ◽  
Development Time ◽  
The Body ◽  
Regression Analyses ◽  
Maternal Body ◽  
Egg Mortality ◽  
The Relationship ◽  
Personal Research

Analyses of the relationship between the size and the number of eggs per female in various decapods, isopods, cumaceans and mysids were made by Jensen (1958) based upon personal research and information from available literature. Regression analyses indicated that the number of eggs per female is related to the cube of the body length.

scholarly journals Female manipulation of offspring sex ratio in the gregarious parasitoidAnaphes flavipesfrom a new two-generation approach

2021 ◽  
Author(s):  
Alena Samková ◽  
Jan Raška ◽  
Jiří Hadrava ◽  
Jiří Skuhrovec ◽  
Petr Janšta
Keyword(s):  
Sex Ratio ◽  
Clutch Size ◽  
Empirical Work ◽  
External Factors ◽  
Offspring Sex Ratio ◽  
Future Fertility ◽  
Offspring Sex ◽  
Body Sizes ◽  
F2 Generation ◽  
F1 Generation

ABSTRACTBoth theoretical and empirical work suggests that offspring sex ratio has important consequences on fitness. Within insects, gregarious parasitoids with haplodiploid sex determination represent an ideal model for studying the decision-making process behind the assignment of offspring sex. To gain insight into the offspring sex ratio of gregarious parasitoids, we performed experiments onAnaphes flavipes, interpreting our results through a two-generation approach. We confirm the existence of a relationship between offspring sex ratio and clutch size: the proportion of males increases with larger clutch size. Based on this finding, we assumed that the proportion of males among one female’s offspring would also increase with external factors such as a low population density of the host or the presence of the host’s predator, which may pressure the mothers to lay a higher-sized clutch. Contrary to our initial expectations, we show that if it is the pressure of external factors that leads to an increase in clutch size, these larger clutches tend to be more female-biased and the overall offspring sex ratio of a particular female does not change. While in our previous work, we showed that higher clutch sizes reduce body sizes of the offspring and their future fertility, here we conclude that the differences in fertility affect the offspring sex ratio. Taken together, we highlight our two-generation approach which reveals that while the above external factors do not affect the sex ratio ofA. flavipesin the F1 generation, they do have an effect in the F2 generation.

Egg size and shape, clutch dynamics, and reproductive effort in European tortoises

1988 ◽  
Vol 66 (7) ◽  
pp. 1527-1536 ◽  
Author(s):  
A. Hailey ◽  
N. S. Loumbourdis
Keyword(s):  
Body Size ◽  
Clutch Size ◽  
Egg Production ◽  
Egg Size ◽  
Reproductive Effort ◽  
Energy Content ◽  
The Body ◽  
Female Reproduction ◽  
Northern Greece ◽  
Clutch Mass

Energetic aspects of female reproduction are described for the tortoises Testudo graeca, Testudo marginata, and Testudo hermanni (three populations of different body size) from northern Greece. Egg width increased with body size in some populations, but smaller individuals produced more elongate eggs, and egg weight was not related to body size. This method for overcoming the constraint of the width of the pelvic canal means that egg width is a poor measure of egg size. Clutch size, clutch mass, and annual egg production varied with body size between populations. Mean relative clutch mass ranged from 4 to 7%, and was highest in the three populations of T. hermanni. All populations laid two or three clutches per year, based on the total number of eggs and large follicles divided by clutch size. Multiple clutches reflect the morphological constraint of packing shelled eggs within the body, rather than energy accumulation during the nesting period. Material for reproduction was stored in growing follicles rather than fat bodies; follicles reached half of their final weight before the animals entered hibernation. Annual reproductive effort as a proportion of body energy content was about 15% in all populations. This is lower than in other reptiles, partly because the carapace accounts for over half of the total ash-free dry weight of the tortoise body.

The Body Size of Headstarted and Wild Juvenile European Pond Turtles (Emys orbicularis)

2017 ◽  
Vol 25 (2) ◽  
pp. 161
Author(s):  
Sławomir Mitrus ◽  
Bartłomiej Najbar ◽  
Adam Kotowicz ◽  
Anna Najbar
Keyword(s):  
Body Size ◽  
The Body ◽  
Emys Orbicularis
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