scholarly journals Within-host competition drives energy allocation trade-offs in an insect parasitoid

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e8810
Author(s):  
J. Keaton Wilson ◽  
Laura Ruiz ◽  
Goggy Davidowitz

Organismal body size is an important biological trait that has broad impacts across scales of biological organization, from cells to ecosystems. Size is also deeply embedded in life history theory, as the size of an individual is one factor that governs the amount of available resources an individual is able to allocate to different structures and systems. A large body of work examining resource allocation across body sizes (allometry) has demonstrated patterns of allocation to different organismal systems and morphologies, and extrapolated rules governing biological structure and organization. However, the full scope of evolutionary and ecological ramifications of these patterns have yet to be realized. Here, we show that density-dependent larval competition in a natural population of insect parasitoids (Drino rhoeo: Tachinidae) results in a wide range of body sizes (largest flies are more than six times larger (by mass) than the smallest flies). We describe strong patterns of trade-offs between different body structures linked to dispersal and reproduction that point to life history strategies that differ between both males and females and individuals of different sizes. By better understanding the mechanisms that generate natural variation in body size and subsequent effects on the evolution of life history strategies, we gain better insight into the evolutionary and ecological impacts of insect parasitoids in tri-trophic systems.

2006 ◽  
Vol 362 (1486) ◽  
pp. 1873-1886 ◽  
Author(s):  
Oliver Krüger

The interactions between brood parasitic birds and their host species provide one of the best model systems for coevolution. Despite being intensively studied, the parasite–host system provides ample opportunities to test new predictions from both coevolutionary theory as well as life-history theory in general. I identify four main areas that might be especially fruitful: cuckoo female gentes as alternative reproductive strategies, non-random and nonlinear risks of brood parasitism for host individuals, host parental quality and targeted brood parasitism, and differences and similarities between predation risk and parasitism risk. Rather than being a rare and intriguing system to study coevolutionary processes, I believe that avian brood parasites and their hosts are much more important as extreme cases in the evolution of life-history strategies. They provide unique examples of trade-offs and situations where constraints are either completely removed or particularly severe.


2010 ◽  
Vol 67 (7) ◽  
pp. 1086-1097 ◽  
Author(s):  
Christian Jørgensen ◽  
Øyvind Fiksen

When trade-offs involving predation and mortality are perturbed by human activities, behaviour and life histories are expected to change, with consequences for natural mortality rates. We present a general life history model for fish in which three common relationships link natural mortality to life history traits and behaviour. First, survival increases with body size. Second, survival declines with growth rate due to risks involved with resource acquisition and allocation. Third, fish that invest heavily in reproduction suffer from decreased survival due to costly reproductive behaviour or morphology that makes escapes from predators less successful. The model predicts increased natural mortality rate as an adaptive response to harvesting. This extends previous models that have shown that harvesting may cause smaller body size, higher growth rates, and higher investment in reproduction. The predicted increase in natural mortality is roughly half the fishing mortality over a wide range of harvest levels and parameter combinations such that fishing two fish kills three after evolutionary adaptations have taken place.


2018 ◽  
Vol 28 ◽  
pp. 29-38
Author(s):  
Nicholas S. Gladstone ◽  
Evin T. Carter ◽  
K. Denise Kendall Niemiller ◽  
Lindsey E. Hayter ◽  
Matthew L. Niemiller

Lungless salamanders in the family Plethodontidae exhibit an impressive array of life history strategies and occur in a diversity of habitats, including caves. However, relationships between life history, habitat, and body size remain largely unresolved. During an ongoing study on the demography and life history of the paedomorphic, cave-obligate Berry Cave Salamander (Gyrinophilusgulolineatus, Brandon 1965), we discovered an exceptionally large individual from the type locality, Berry Cave, Roane County, Tennessee, USA. This salamander measured 145 mm in body length and represents not only the largest G.gulolineatus and Gyrinophilus ever reported, but also the largest plethodontid salamander in the United States. We discuss large body size in G.gulolineatus and compare body size in other large plethodontid salamanders in relation to life history and habitat.


2018 ◽  
Author(s):  
John S. Park

ABSTRACTCycles, such as seasons or tides, characterize many systems in nature. Overwhelming evidence shows that climate change-driven alterations to environmental cycles—such as longer seasons— are associated with phenological shifts around the world, suggesting a deep link between environmental cycles and life cycles. However, general mechanisms of life history evolution in cyclical environments are still not well understood. Here I build a demographic framework and ask how life history strategies optimize fitness when the environment perturbs a structured population cyclically, and how strategies should change as cyclicality changes. I show that cycle periodicity alters optimality predictions of classic life history theory because repeated cycles have rippling selective consequences over time and generations. Notably, fitness landscapes that relate environmental cyclicality and life history optimality vary dramatically depending on which trade-offs govern a given species. The model tuned with known life history trade-offs in a marine intertidal copepod T. californicus successfully predicted the shape of life history variation across natural populations spanning a gradient of tidal periodicities. This framework shows how environmental cycles can drive life history variation—without complex assumptions of individual responses to cues such as temperature—thus expanding the range of life history diversity explained by theory and providing a basis for adaptive phenology.


PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7177 ◽  
Author(s):  
Eli S.J. Thoré ◽  
Arnout F. Grégoir ◽  
Bart Adriaenssens ◽  
Charlotte Philippe ◽  
Robby Stoks ◽  
...  

Variation in life-history strategies along a slow-fast continuum is largely governed by life-history trade-offs. The pace-of-life syndrome hypothesis (POLS) expands on this idea and suggests coevolution of these traits with personality and physiology at different levels of biological organization. However, it remains unclear to what extent covariation at different levels aligns and if also behavioral patterns such as diurnal activity changes should be incorporated. Here, we investigate variation in life-history traits as well as behavioral variation at the individual, sex and population level in the Turquoise killifish Nothobranchius furzeri. We performed a common garden laboratory experiment with four populations that differ in pond permanence and scored life-history and behavioral (co-) variation at the individual and population level for both males and females. In addition, we focused on diurnal activity change as a behavioral trait that remains understudied in ecology. Our results demonstrate sex-specific variation in adult body size and diurnal activity change among populations that originate from ponds with differences in permanence. However, there was no pond permanence-dependent divergence in maturation time, juvenile growth rate, fecundity and average activity level. With regard to behavior, individuals differed consistently in locomotor activity and diurnal activity change while, in contrast with POLS predictions, we found no indications for life-history and behavioral covariation at any level. Overall, this study illustrates that diurnal activity change differs consistently between individuals, sexes and populations although this variation does not appear to match POLS predictions.


2011 ◽  
Vol 89 (8) ◽  
pp. 692-704 ◽  
Author(s):  
Evi Paemelaere ◽  
F. Stephen Dobson

The fast–slow continuum hypothesis explains life-history traits as reflecting the causal influence of mortality patterns in interaction with trade-offs among traits, particularly more reproductive effort at a cost of shorter lives. Variation among species of different body sizes produce more or less rapid life cycles (respectively, from small to large species), but the fast–slow continuum remains for birds and mammals when body-size effects are statistically removed. We tested for a fast–slow continuum in mammalian carnivores. We found the above trade-offs initially supported in a sample of 85 species. Body size, however, was strongly associated with phylogeny (ρ = 0.79), and thus we used regression techniques and independent contrasts to make statistical adjustments for both. After adjustments, the life-history trade-offs were not apparent, and few associations of life-history traits were significant. Litter size was negatively associated with age at maturity, but slightly positively associated with offspring mass. Litter size and mass were negatively associated with the length of the developmental period. Gestation length showed weak but significant negative associations with age at maturity and longevity. We conclude that carnivores, despite their wide range of body sizes and variable life histories, at best poorly exhibited a fast–slow continuum.


2019 ◽  
Vol 6 (10) ◽  
pp. 190258 ◽  
Author(s):  
Candice M. Stefanic ◽  
Sterling J. Nesbitt

Living members of Archosauria, the reptile clade containing Crocodylia and Aves, have a wide range of skeletal morphologies, ecologies and body size. The range of body size greatly increases when extinct archosaurs are included, because extinct Archosauria includes the largest members of any terrestrial vertebrate group (e.g. 70-tonne titanosaurs, 20-tonne theropods). Archosaurs evolved various skeletal adaptations for large body size, but these adaptations varied among clades and did not always appear consistently with body size or ecology. Modification of intervertebral articulations, specifically the presence of a hyposphene-hypantrum articulation between trunk vertebrae, occurs in a variety of extinct archosaurs (e.g. non-avian dinosaurs, pseudosuchians). We surveyed the phylogenetic distribution of the hyposphene-hypantrum to test its relationship with body size. We found convergent evolution among large-bodied clades, except when the clade evolved an alternative mechanism for vertebral bracing. For example, some extinct lineages that lack the hyposphene-hypantrum articulation (e.g. ornithischians) have ossified tendons that braced their vertebral column. Ossified tendons are present even in small taxa and in small-bodied juveniles, but large-bodied taxa with ossified tendons reached those body sizes without evolving the hyposphene-hypantrum articulation. The hyposphene-hypantrum was permanently lost in extinct crownward members of both major archosaur lineages (i.e. Crocodylia and Aves) as they underwent phyletic size decrease, changes in vertebral morphology and shifts in ecology.


2021 ◽  
Author(s):  
◽  
Pauline Mitterwallner

<p>Life-history theory suggests that an organism must balance its available energy between two competing physiological processes to maximize fitness: reproduction and somatic growth. Energetic trade-offs are a fundamental concept of life history theory and form the basis of intra- and inter-specific variation in life-history strategies. In fishes, reproduction-growth trade-offs are an essential component of life-history optimization. This is particularly true for species with protogynous sex- change (the most common reproductive mode among coral reef fish species), where reproductive success rapidly and disproportionally increases with body size/ corresponding social status. In such systems, lifetime fitness is inherently linked to patterns of growth and energy allocation strategies determined by an individual’s size-specific rank within the dominance hierarchy. However, energy allocation strategies in a protogynous species may not only be a function of body size. Coral reef fish species are exposed to extremely variable environmental conditions and this can favour the evolution of strategies that utilize good times and avoid disadvantageous times for reproduction. Consequently, size- specific parental investment decisions may vary greatly in time and space according to environmental cues. My thesis focuses on the protogynous reef fish, Thalassoma hardwicke (the sixbar wrasse), which is extremely abundant on shallow coral reefs throughout the Indo-Pacific region. Specifically, I evaluate patterns of spawning and reproductive investment as a function of body size, social status, lunar phase and other environmental parameters. I address the question of whether females/males of differing size make different fitness-related decisions when away from spawning sites, and I evaluate context-dependency in these decisions. Finally, I will attempt to reconstruct the developmental histories (e.g., larval growth rates) of individuals from otoliths to evaluate potential relationships between developmental histories and fitness attributes.</p>


2021 ◽  
Author(s):  
◽  
Pauline Mitterwallner

<p>Life-history theory suggests that an organism must balance its available energy between two competing physiological processes to maximize fitness: reproduction and somatic growth. Energetic trade-offs are a fundamental concept of life history theory and form the basis of intra- and inter-specific variation in life-history strategies. In fishes, reproduction-growth trade-offs are an essential component of life-history optimization. This is particularly true for species with protogynous sex- change (the most common reproductive mode among coral reef fish species), where reproductive success rapidly and disproportionally increases with body size/ corresponding social status. In such systems, lifetime fitness is inherently linked to patterns of growth and energy allocation strategies determined by an individual’s size-specific rank within the dominance hierarchy. However, energy allocation strategies in a protogynous species may not only be a function of body size. Coral reef fish species are exposed to extremely variable environmental conditions and this can favour the evolution of strategies that utilize good times and avoid disadvantageous times for reproduction. Consequently, size- specific parental investment decisions may vary greatly in time and space according to environmental cues. My thesis focuses on the protogynous reef fish, Thalassoma hardwicke (the sixbar wrasse), which is extremely abundant on shallow coral reefs throughout the Indo-Pacific region. Specifically, I evaluate patterns of spawning and reproductive investment as a function of body size, social status, lunar phase and other environmental parameters. I address the question of whether females/males of differing size make different fitness-related decisions when away from spawning sites, and I evaluate context-dependency in these decisions. Finally, I will attempt to reconstruct the developmental histories (e.g., larval growth rates) of individuals from otoliths to evaluate potential relationships between developmental histories and fitness attributes.</p>


2018 ◽  
Author(s):  
Clémentine Renneville ◽  
Alexis Millot ◽  
Simon Agostini ◽  
David Carmignac ◽  
Gersende Maugars ◽  
...  

ABSTRACTAnthropogenic perturbations such as harvesting often select against a large body size and are predicted to induce rapid evolution towards smaller body sizes and earlier maturation. However, body-size evolvability and, hence, adaptability to anthropogenic perturbations remain seldom evaluated in wild populations. Here, we use a laboratory experiment over 6 generations to measure the ability of wild-caught medaka fish (Oryzias latipes) to evolve in response to bidirectional size-dependent selection mimicking opposite harvest regimes. Specifically, we imposed selection against a small body size (Large line), against a large body size (Small line) or random selection (Control line), and measured correlated responses across multiple phenotypic, life-history and endocrine traits. As expected, the Large line evolved faster somatic growth and delayed maturation, but also evolved smaller body sizes at hatch, with no change in average levels of pituitary gene expressions of luteinizing, folliclestimulating or growth (GH) hormones. In contrast, the Small medaka line was unable to evolve smaller body sizes or earlier maturation, but evolved smaller body sizes at hatch and showed marginally-significant signs of increased reproductive investment, including larger egg sizes and elevated pituitary GH production. Natural selection on medaka body size was too weak to significantly hinder the effect of artificial selection, indicating that the asymmetric body-size response to size-dependent selection reflected an asymmetry in body-size evolvability. Our results show that trait evolvability may be contingent upon the direction of selection, and that a detailed knowledge of trait evolutionary potential is needed to forecast population response to anthropogenic change.


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