scholarly journals Starvation reveals the cause of infection-induced castration and gigantism

2014 ◽  
Vol 281 (1792) ◽  
pp. 20141087 ◽  
Author(s):  
Clayton E. Cressler ◽  
William A. Nelson ◽  
Troy Day ◽  
Edward McCauley
Keyword(s):  
Life History ◽  
Energy Budget ◽  
Life History Variation ◽  
Starvation Stress ◽  
Parasite Fitness ◽  
Pasteuria Ramosa ◽  
Investment In Reproduction ◽  
Growth Energy ◽  
Host Parasite

Parasites often induce life-history changes in their hosts. In many cases, these infection-induced life-history changes are driven by changes in the pattern of energy allocation and utilization within the host. Because these processes will affect both host and parasite fitness, it can be challenging to determine who benefits from them. Determining the causes and consequences of infection-induced life-history changes requires the ability to experimentally manipulate life history and a framework for connecting life history to host and parasite fitness. Here, we combine a novel starvation manipulation with energy budget models to provide new insights into castration and gigantism in the Daphnia magna – Pasteuria ramosa host–parasite system. Our results show that starvation primarily affects investment in reproduction, and increasing starvation stress reduces gigantism and parasite fitness without affecting castration. These results are consistent with an energetic structure where the parasite uses growth energy as a resource. This finding gives us new understanding of the role of castration and gigantism in this system, and how life-history variation will affect infection outcome and epidemiological dynamics. The approach of combining targeted life-history manipulations with energy budget models can be adapted to understand life-history changes in other disease systems.

scholarly journals Artificial selection reveals the role of transcriptional constraints in the maintenance of life history variation

2020 ◽  
Vol 4 (3) ◽  
pp. 200-211 ◽  
Author(s):  
Joel L. Pick ◽  
Masaomi Hatakeyama ◽  
Kate E. Ihle ◽  
Julien Gasparini ◽  
Claudy Haussy ◽  
...  
Keyword(s):  
Life History ◽  
Artificial Selection ◽  
Life History Variation

Host life-history variation in response to parasitism

Parasitology ◽  
1985 ◽  
Vol 90 (1) ◽  
pp. 205-216 ◽  
Author(s):  
D. J. Minchella
Keyword(s):  
Genetic Variation ◽  
Life History ◽  
Parasitic Infection ◽  
Host Susceptibility ◽  
Life History Variation ◽  
Susceptible Host ◽  
Finite Set ◽  
Host Life ◽  
Host Parasite ◽  
Parasite Populations

Over half of all living species of plants and animals are parasitic, which by definition involves intimate association with and unfavourable impact on hosts (Price, 1980). This paper will only consider parasites whose ‘unfavourable impact’ adversely affects the birth and/or mortality rates of their hosts (Anderson, 1978). Most organisms are potential hosts and must deal with the problem of parasitism. The probability of parasitic infection of a host is influenced by both environmental and genetic factors. Traditionally it was assumed that a host was either resistant or susceptible to a particular parasite and therefore the interaction between a parasite and potential host had only two possible outcomes: either the resistant host rebuffed the parasitic attack and remained uninfected or the parasite successfully invaded and significantly reduced the reproductive success of the susceptible host. This approach, however, ignored the intraspecific genetic variation present within both host and parasite populations (Wakelin, 1978). Since the outcome is determined by the interaction of a finite set of host genes and parasite genes, genetic variation in host susceptibility and parasite infectivity (Richards, 1976; Wakelin, 1978) suggests that more than two outcomes are possible. Variation in host and parasite genomes does not begin and end at the susceptibility/infectivity loci. Other genes may also influence the outcome of host–parasite interactions by altering the life-history patterns of hosts and parasites, and lead to a variety of outcomes.

scholarly journals Differential reproductive responses to stress reveal the role of life-history strategies within a species

2013 ◽  
Vol 280 (1771) ◽  
pp. 20132090 ◽  
Author(s):  
J. Schultner ◽  
A. S. Kitaysky ◽  
G. W. Gabrielsen ◽  
S. A. Hatch ◽  
C. Bech
Keyword(s):  
Life History ◽  
Life History Theory ◽  
Life History Strategies ◽  
Short Term ◽  
Food Shortages ◽  
Investment In Reproduction ◽  
Response To Stress ◽  
Environmental Events ◽  
Two Populations

Life-history strategies describe that ‘slow’- in contrast to ‘fast’-living species allocate resources cautiously towards reproduction to enhance survival. Recent evidence suggests that variation in strategies exists not only among species but also among populations of the same species. Here, we examined the effect of experimentally induced stress on resource allocation of breeding seabirds in two populations with contrasting life-history strategies: slow-living Pacific and fast-living Atlantic black-legged kittiwakes. We tested the hypothesis that reproductive responses in kittiwakes under stress reflect their life-history strategies. We predicted that in response to stress, Pacific kittiwakes reduce investment in reproduction compared with Atlantic kittiwakes. We exposed chick-rearing kittiwakes to a short-term (3-day) period of increased exogenous corticosterone (CORT), a hormone that is released during food shortages. We examined changes in baseline CORT levels, parental care and effects on offspring. We found that kittiwakes from the two populations invested differently in offspring when facing stress. In response to elevated CORT, Pacific kittiwakes reduced nest attendance and deserted offspring more readily than Atlantic kittiwakes. We observed lower chick growth, a higher stress response in offspring and lower reproductive success in response to CORT implantation in Pacific kittiwakes, whereas the opposite occurred in the Atlantic. Our findings support the hypothesis that life-history strategies predict short-term responses of individuals to stress within a species. We conclude that behaviour and physiology under stress are consistent with trade-off priorities as predicted by life-history theory. We encourage future studies to consider the pivotal role of life-history strategies when interpreting inter-population differences of animal responses to stressful environmental events.

scholarly journals The Phylogenetic Approach to Avian Life Histories: An Important Complement to Within-Population Studies

The Condor ◽  
2000 ◽  
Vol 102 (1) ◽  
pp. 52-59 ◽  
Author(s):  
David W. Winkler
Keyword(s):  
Life History ◽  
Life Histories ◽  
Life History Traits ◽  
Statistical Convergence ◽  
Phylogenetic Analyses ◽  
Life History Evolution ◽  
Life History Variation ◽  
Evolution Of Life ◽  
Character Variation

Abstract In recent years, two approaches have emerged for the analysis of character evolution: the largely statistical “convergence” approach and the mainly cladistic “homology” approach. I discuss the strengths and weaknesses of these approaches as they apply to phylogenetic analyses of life-history variation in birds. Using examples from analyses of character variation in swallows, I suggest that the phylogenetic approach yields distinctive insights into the selective role of the environment and other characters of the organism on the evolution of life-history traits. This view thus has the potential of bringing together micro- and macro-evolutionary views of life-history evolution.

scholarly journals Genetic variation in the cellular response of Daphnia magna (Crustacea: Cladocera) to its bacterial parasite

2010 ◽  
Vol 277 (1698) ◽  
pp. 3291-3297 ◽  
Author(s):  
Stuart K. J. R. Auld ◽  
Jennifer A. Scholefield ◽  
Tom J. Little
Keyword(s):  
Genetic Variation ◽  
Daphnia Magna ◽  
Cellular Response ◽  
Cell Types ◽  
Parasite Fitness ◽  
Pasteuria Ramosa ◽  
Cellular Immune ◽  
Genetically Determined ◽  
Host Parasite ◽  
Parasite Exposure

Linking measures of immune function with infection, and ultimately, host and parasite fitness is a major goal in the field of ecological immunology. In this study, we tested for the presence and timing of a cellular immune response in the crustacean Daphnia magna following exposure to its sterilizing endoparasite Pasteuria ramosa . We found that D. magna possesses two cell types circulating in the haemolymph: a spherical one, which we call a granulocyte and an irregular-shaped amoeboid cell first described by Metchnikoff over 125 years ago. Daphnia magna mounts a strong cellular response (of the amoeboid cells) just a few hours after parasite exposure. We further tested for, and found, considerable genetic variation for the magnitude of this cellular response. These data fostered a heuristic model of resistance in this naturally coevolving host–parasite interaction. Specifically, the strongest cellular responses were found in the most susceptible hosts, indicating resistance is not always borne from a response that destroys invading parasites, but rather stems from mechanisms that prevent their initial entry. Thus, D. magna may have a two-stage defence—a genetically determined barrier to parasite establishment and a cellular response once establishment has begun.

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