scholarly journals The roles of environmental variation and parasite survival in virulence–transmission relationships

2021 ◽  
Vol 8 (6) ◽  
pp. 210088
Author(s):  
Wendy C. Turner ◽  
Pauline L. Kamath ◽  
Henriette van Heerden ◽  
Yen-Hua Huang ◽  
Zoe R. Barandongo ◽  
...  
Keyword(s):  
Life History ◽  
Adaptive Dynamics ◽  
Life History Evolution ◽  
Infectious Agent ◽  
Environmental Context ◽  
Parasite Life Cycle ◽  
Trade Offs ◽  
Evolution Of Virulence ◽  
Parasite Survival ◽  
Host Parasite

Disease outbreaks are a consequence of interactions among the three components of a host–parasite system: the infectious agent, the host and the environment. While virulence and transmission are widely investigated, most studies of parasite life-history trade-offs are conducted with theoretical models or tractable experimental systems where transmission is standardized and the environment controlled. Yet, biotic and abiotic environmental factors can strongly affect disease dynamics, and ultimately, host–parasite coevolution. Here, we review research on how environmental context alters virulence–transmission relationships, focusing on the off-host portion of the parasite life cycle, and how variation in parasite survival affects the evolution of virulence and transmission. We review three inter-related ‘approaches’ that have dominated the study of the evolution of virulence and transmission for different host–parasite systems: (i) evolutionary trade-off theory, (ii) parasite local adaptation and (iii) parasite phylodynamics. These approaches consider the role of the environment in virulence and transmission evolution from different angles, which entail different advantages and potential biases. We suggest improvements to how to investigate virulence–transmission relationships, through conceptual and methodological developments and taking environmental context into consideration. By combining developments in life-history evolution, phylogenetics, adaptive dynamics and comparative genomics, we can improve our understanding of virulence–transmission relationships across a diversity of host–parasite systems that have eluded experimental study of parasite life history.

Comparing life histories using phylogenies

1991 ◽  
Vol 332 (1262) ◽  
pp. 31-39 ◽  
Keyword(s):  
Life History ◽  
Life Histories ◽  
Comparative Method ◽  
Life History Evolution ◽  
Trade Offs ◽  
Evolution Of Life ◽  
Show Evidence ◽  
Selective Forces ◽  
Host Parasite ◽  
Optimality Models

The comparative method as recently developed can be used to identify statistically independent instances of life-history evolution. When life-history traits show evidence for correlated evolutionary change with each other or with ecological differences, it is often possible to single out the trade-offs and selective forces responsible for the evolution of life-history diversity. Suites of life-history characters often evolve in concert, and recent optimality models incorporating few variables show promise for interpreting that evolution in terms of few selective forces. Because hosts provide well-defined environments for their parasites, when host-parasite phylogenies are congruent it is possible to test ideas about the evolution of particular life-history and size-related traits.

scholarly journals The physiological costs of reproduction in small mammals

2007 ◽  
Vol 363 (1490) ◽  
pp. 375-398 ◽  
Author(s):  
John R Speakman
Keyword(s):  
Life History ◽  
Small Mammals ◽  
Morphological Changes ◽  
Life History Evolution ◽  
Indirect Costs ◽  
Direct Costs ◽  
Costs Of Reproduction ◽  
Dominant Component ◽  
Trade Offs ◽  
Almost All

Life-history trade-offs between components of fitness arise because reproduction entails both gains and costs. Costs of reproduction can be divided into ecological and physiological costs. The latter have been rarely studied yet are probably a dominant component of the effect. A deeper understanding of life-history evolution will only come about once these physiological costs are better understood. Physiological costs may be direct or indirect. Direct costs include the energy and nutrient demands of the reproductive event, and the morphological changes that are necessary to facilitate achieving these demands. Indirect costs may be optional ‘compensatory costs’ whereby the animal chooses to reduce investment in some other aspect of its physiology to maximize the input of resource to reproduction. Such costs may be distinguished from consequential costs that are an inescapable consequence of the reproductive event. In small mammals, the direct costs of reproduction involve increased energy, protein and calcium demands during pregnancy, but most particularly during lactation. Organ remodelling is necessary to achieve the high demands of lactation and involves growth of the alimentary tract and associated organs such as the liver and pancreas. Compensatory indirect costs include reductions in thermogenesis, immune function and physical activity. Obligatory consequential costs include hyperthermia, bone loss, disruption of sleep patterns and oxidative stress. This is unlikely to be a complete list. Our knowledge of these physiological costs is currently at best described as rudimentary. For some, we do not even know whether they are compensatory or obligatory. For almost all of them, we have no idea of exact mechanisms or how these costs translate into fitness trade-offs.

scholarly journals Life‐history evolution in the anthropocene: effects of increasing nutrients on traits and trade‐offs

2015 ◽  
Vol 8 (7) ◽  
pp. 635-649 ◽  
Author(s):  
Emilie Snell‐Rood ◽  
Rickey Cothran ◽  
Anne Espeset ◽  
Punidan Jeyasingh ◽  
Sarah Hobbie ◽  
...  
Keyword(s):  
Life History ◽  
Life History Evolution ◽  
Trade Offs ◽  
History Evolution

Trade-Offs in Life-History Evolution

1989 ◽  
Vol 3 (3) ◽  
pp. 259 ◽  
Author(s):  
S. C. Stearns
Keyword(s):  
Life History ◽  
Life History Evolution ◽  
Trade Offs ◽  
History Evolution

Benefits of fidelity: does host specialization impact nematode parasite life history and fecundity?

Parasitology ◽  
2013 ◽  
Vol 140 (5) ◽  
pp. 587-597 ◽  
Author(s):  
J. KOPRIVNIKAR ◽  
H. S. RANDHAWA
Keyword(s):  
Life History ◽  
Host Specificity ◽  
Egg Size ◽  
Host Specialization ◽  
Published Data ◽  
Female Size ◽  
Patent Period ◽  
Trade Offs ◽  
Evolutionary Level ◽  
Host Parasite

SUMMARYThe range of hosts used by a parasite is influenced by macro-evolutionary processes (host switching, host–parasite co-evolution), as well as ‘encounter filters’ and ‘compatibility filters’ at the micro-evolutionary level driven by host/parasite ecology and physiology. Host specialization is hypothesized to result in trade-offs with aspects of parasite life history (e.g. reproductive output), but these have not been well studied. We used previously published data to create models examining general relationships among host specificity and important aspects of life history and reproduction for nematodes parasitizing animals. Our results indicate no general trade-off between host specificity and the average pre-patent period (time to first reproduction), female size, egg size, or fecundity of these nematodes. However, female size was positively related to egg size, fecundity, and pre-patent period. Host compatibility may thus not be the primary determinant of specificity in these parasitic nematodes if there are few apparent trade-offs with reproduction, but rather, the encounter opportunities for new host species at the micro-evolutionary level, and other processes at the macro-evolutionary level (i.e. phylogeny). Because host specificity is recognized as a key factor determining the spread of parasitic diseases understanding factors limiting host use are essential to predict future changes in parasite range and occurrence.

Intraspecific variation in reproductive effort by female Parapediasia teterrella (Lepidoptera: Pyralidae) and its relation to body size

1990 ◽  
Vol 68 (1) ◽  
pp. 44-48 ◽  
Author(s):  
Larry D. Marshall
Keyword(s):  
Life History ◽  
Body Size ◽  
Egg Production ◽  
Egg Size ◽  
Reproductive Effort ◽  
Life History Evolution ◽  
Reproductive Parameters ◽  
Trade Offs ◽  
Egg Number ◽  
Lepidoptera Pyralidae

Daily egg production of the moth Parapediasia teterrella declined over the life-span of the female but egg size remained constant. The absence of water resulted in lower fecundity and early mortality. Egg size and lifetime fecundity showed considerable inter-individual variation and large females produced more and larger eggs than their smaller counterparts. Large females expended greater reproductive effort than small females. Hatching success was negatively related to egg size. In spite of this, large females laying large eggs had higher fitness than small females. I postulate that multiple reproductive strategies within a species, resulting from differences in reproductive effort expended, may explain why expected trade-offs in reproductive parameters (e.g., egg size versus egg number) were not found in this species. Furthermore, I argue that the prevalent interpretation of life-history evolution (that body size is the important determining parameter of life-history parameters) may reflect correlation of body size with reproductive effort, and reproductive effort may be more important in determining the nature of trade-offs between reproductive parameters.

scholarly journals Physiological demands and nutrient intake modulate a trade-off between dispersal and reproduction based on age and sex of field crickets

2021 ◽  
Vol 224 (7) ◽  
Author(s):  
Lisa A. Treidel ◽  
Rebecca M. Clark ◽  
Melissa T. Lopez ◽  
Caroline M. Williams
Keyword(s):  
Life History ◽  
Flight Muscle ◽  
Life History Strategy ◽  
Life History Evolution ◽  
Resource Acquisition ◽  
Muscle Quality ◽  
Field Crickets ◽  
Trade Offs ◽  
Physiological Demands ◽  
Age And Sex

ABSTRACT Animals adjust resource acquisition throughout life to meet changing physiological demands of growth, reproduction, activity and somatic maintenance. Wing-polymorphic crickets invest in either dispersal or reproduction during early adulthood, providing a system in which to determine how variation in physiological demands, determined by sex and life history strategy, impact nutritional targets, plus the consequences of nutritionally imbalanced diets across life stages. We hypothesized that high demands of biosynthesis (especially oogenesis in females) drive elevated resource acquisition requirements and confer vulnerability to imbalanced diets. Nutrient targets and allocation into key tissues associated with life history investments were determined for juvenile and adult male and female field crickets (Gryllus lineaticeps) when given a choice between two calorically equivalent but nutritionally imbalanced (protein- or carbohydrate-biased) artificial diets, or when restricted to one imbalanced diet. Flight muscle synthesis drove elevated general caloric requirements for juveniles investing in dispersal, but flight muscle quality was robust to imbalanced diets. Testes synthesis was not costly, and life history investments by males were insensitive to diet composition. In contrast, costs of ovarian synthesis drove elevated caloric and protein requirements for adult females. When constrained to a carbohydrate-biased diet, ovary synthesis was reduced in reproductive morph females, eliminating their advantage in early life fecundity over the dispersal morph. Our findings demonstrate that nutrient acquisition modulates dispersal–reproduction trade-offs in an age- and sex-specific manner. Declines in food quality will thus disproportionately affect specific cohorts, potentially driving demographic shifts and altering patterns of life history evolution.

scholarly journals Reactive oxygen species as universal constraints in life-history evolution

2009 ◽  
Vol 276 (1663) ◽  
pp. 1737-1745 ◽  
Author(s):  
Damian K. Dowling ◽  
Leigh W. Simmons
Keyword(s):  
Reactive Oxygen Species ◽  
Life History ◽  
Evolutionary Biology ◽  
Sperm Quality ◽  
Reactive Oxygen ◽  
Life History Evolution ◽  
Oxygen Species ◽  
Trade Offs ◽  
Wide Range ◽  
History Evolution

Evolutionary theory is firmly grounded on the existence of trade-offs between life-history traits, and recent interest has centred on the physiological mechanisms underlying such trade-offs. Several branches of evolutionary biology, particularly those focusing on ageing, immunological and sexual selection theory, have implicated reactive oxygen species (ROS) as profound evolutionary players. ROS are a highly reactive group of oxygen-containing molecules, generated as common by-products of vital oxidative enzyme complexes. Both animals and plants appear to intentionally harness ROS for use as molecular messengers to fulfil a wide range of essential biological processes. However, at high levels, ROS are known to exert very damaging effects through oxidative stress. For these reasons, ROS have been suggested to be important mediators of the cost of reproduction, and of trade-offs between metabolic rate and lifespan, and between immunity, sexual ornamentation and sperm quality. In this review, we integrate the above suggestions into one life-history framework, and review the evidence in support of the contention that ROS production will constitute a primary and universal constraint in life-history evolution.

Reproductive Effort and Costs

2021 ◽  
pp. 59-74
Author(s):  
Jeffrey A. Hutchings
Keyword(s):  
Life History ◽  
Reproductive Success ◽  
Total Energy ◽  
Reproductive Effort ◽  
Life History Evolution ◽  
Reproductive Costs ◽  
Positive Outcomes ◽  
Differential Allocation ◽  
Trade Offs ◽  
Potential Benefits

Predictions about life-history evolution are intellectually bereft without a consideration of trade-offs. Benefits derived from making one life-history ‘decision’ are made at a cost of not realizing potential benefits associated with alternative decisions. These trade-offs are the inevitable product of constraints, often driven by an individual’s differential allocation of fixed resources to reproduction versus survival or growth. These allocations prevent multiple positive outcomes from being simultaneously realized. Reproductive effort is the proportion of total energy or resources allocated to all elements of reproduction. Reproductive effort generates reproductive costs. Increases in current reproductive effort reduce future reproductive success by affecting survival, growth, and/or fecundity. The causal mechanisms of these costs can be energetic, ecological, behavioural, or genetic. Evidence for reproductive costs is widespread. Instances where the evidence of costs is equivocal are usually caused by using among-individual correlations to study what is a within-individual phenomenon.

Life history evolution in heterogeneous environments: a review of theory

1996 ◽  
Vol 351 (1345) ◽  
pp. 1349-1359 ◽  
Keyword(s):  
Life History ◽  
Life History Evolution ◽  
Common Garden ◽  
Experimental Tests ◽  
Heterogeneous Environments ◽  
Simulation Studies ◽  
Trade Offs ◽  
Fitness Measures ◽  
History Evolution ◽  
Common Garden Experiments

Analysis of life history evolution in spatially heterogeneous environments was revolutionized by the demonstration by Kawecki & Stearns (1993) and Houston & McNamara (1992) that earlier treatments had used incorrect fitness measures. The implications of this for the analysis of organisms with and without phenotypic plasticity are reviewed. It is shown that analyses ignoring age structure can give misleading results. The plausibility and implications of the assumptions are discussed, and suggestions are made for further work. The usefulness of reciprocal transplant and common garden experiments, in providing information relevant to the assumptions and predictions, is emphasized. Two simulation studies show that life history evolution in temporally heterogeneous environments in which trade-offs are fixed are well predicted by Schaffer’s (1974) model, with modification for asymmetric variations as necessary. Unfortunately the period of study needed to observe such effects is so long as to preclude experimental tests for most organsims.

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