Optimal Life Histories and the Maximization of Reproductive Value: A General Theorem for Complex Life Cycles

Ecology ◽  
1982 ◽  
Vol 63 (5) ◽  
pp. 1218-1222 ◽  
Author(s):  
Hal Caswell
Keyword(s):  
Life Histories ◽  
General Theorem ◽  
Life Cycles ◽  
Reproductive Value ◽  
Complex Life Cycles ◽  
Optimal Life Histories

scholarly journals Molecular signatures of the rediae, cercariae and adult worm stages in the complex life cycles of parasitic flatworms (Psilostomatidae, Trematoda)

2019 ◽  
Author(s):  
Maksim A. Nesterenko ◽  
Viktor V. Starunov ◽  
Sergei V. Shchenkov ◽  
Anna R. Maslova ◽  
Sofia A. Denisova ◽  
...  
Keyword(s):  
Adult Worm ◽  
Related Species ◽  
Life Histories ◽  
Expression Patterns ◽  
Life Forms ◽  
Life Cycles ◽  
Complex Life Cycle ◽  
Molecular Signatures ◽  
Life Stages ◽  
Complex Life Cycles

AbstractTrematodes are one of the most remarkable animals with complex life cycles with several generations. Life histories of a parasitic flatworms include several stages with disparate morphological and physiological characteristics follow each other and infect hosts ranging from mollusks to higher vertebrates. How does one genome regulate the development of various life forms and how many genes are needed to the functioning of each stages? How similar are molecular signatures of life stages in closely related species of parasitic flatworms? Here we present the comparative analysis of transcriptomic signatures of the rediae, cercaria and adult worm stages in two representatives of the family Psilostomatidae (Echinostomata, Trematoda) -Psilotrema simillimumandSphaeridiotrema pseudoglobulus. Our results indicate that the transitions between the stages of the complex life cycle are associated with massive changes in gene expression with thousands of genes being stage-specific. In terms of expression dynamics, the adult worm is the most similar stage betweenPsilotremaandSpaeridiotrema, while expression patterns of genes in the rediae and cercariae stages are much more different. This study provides transcriptomic evidences not only for similarities and differences between life stages of two related species, but also for cryptic species inSphaeridiotrema.

Pyxidiophora: life histories and arthropod associations of two species

1989 ◽  
Vol 67 (9) ◽  
pp. 2552-2562 ◽  
Author(s):  
Meredith Blackwell ◽  
David Malloch
Keyword(s):  
Life Cycle ◽  
New Brunswick ◽  
Life Histories ◽  
Field Studies ◽  
Life Cycles ◽  
Frequent Occurrence ◽  
Evolutionary Significance ◽  
Complex Life Cycles ◽  
Phoretic Mite

Based on field studies in New Brunswick and Ontario, two species of the genus Pyxidiophora are demonstrated to be of frequent occurrence. Pyxidiophora sp. and Pyxidiophora spinuliformis have complex life cycles involving anamorph formation and sporulation on a phoretic mite host. Pyxidiophora sp., the more common of the two species, appears to be parasitic on the apothecia of coprophilous Pezizales where it forms clusters of synnemata within a week of dung deposition. Later, perithecia develop among the synnemata and produce ascospores. Ascospores attach to mites that are, in turn, carried by beetles and flies to a new substrate. On the new substrate while attached to the mite, ascospores of Pyxidiophora sp. differentiate into linearly arranged or complex and often muriform Thaxteriola thalli, which produce phialoconidia. The phialoconidia appear to be the propagules that inoculate the new substrate. Pyxidiophora spinuliformis has a life cycle similar to that of Pyxidiophora sp. but differs in having a conidial anamorph with a different development and ascospores that never form muriform thalli on the phoretic mite host. The taxonomic, ecological, and evolutionary significance of these findings is discussed.

scholarly journals Robustness of life histories to environmental variability in complex versus simple life cycles

2021 ◽  
Author(s):  
Annie Jonsson
Keyword(s):  
Growth Rate ◽  
Life Histories ◽  
Environmental Variability ◽  
Life Cycles ◽  
Relative Advantage ◽  
Complex Life Cycle ◽  
Life Stages ◽  
Vital Rates ◽  
Habitat Separation ◽  
Simple Life

AbstractMost animal species have a complex life cycle (CLC) with metamorphosis. It is thus of interest to examine possible benefits of such life histories. The prevailing view is that CLC represents an adaptation for genetic decoupling of juvenile and adult traits, thereby allowing life stages to respond independently to different selective forces. Here I propose an additional potential advantage of CLCs that is, decreased variance in population growth rate due to habitat separation of life stages. Habitat separation of pre- and post-metamorphic stages means that the stages will experience different regimes of environmental variability. This is in contrast to species with simple life cycles (SLC) whose life stages often occupy one and the same habitat. The correlation in the fluctuations of the vital rates of life stages is therefore likely to be weaker in complex than in simple life cycles. By a theoretical framework using an analytical approach, I have (1) derived the relative advantage, in terms of long-run growth rate, of CLC over SLC phenotypes for a broad spectrum of life histories, and (2) explored which life histories that benefit most by a CLC, that is avoid correlation in vital rates between life stages. The direction and magnitude of gain depended on life history type and fluctuating vital rate. One implication of our study is that species with CLCs should, on average, be more robust to increased environmental variability caused by global warming than species with SLCs.

scholarly journals Impacts of climate change on the complex life cycles of fish

2012 ◽  
Vol 22 (2) ◽  
pp. 121-139 ◽  
Author(s):  
Pierre Petitgas ◽  
Adriaan D. Rijnsdorp ◽  
Mark Dickey-Collas ◽  
Georg H. Engelhard ◽  
Myron A. Peck ◽  
...  
Keyword(s):  
Climate Change ◽  
Life Cycles ◽  
Complex Life Cycles ◽  
Impacts Of Climate Change

Complex Life Cycles: Why Refrain from Growth before Reproduction in the Adult Niche?

2013 ◽  
Vol 181 (1) ◽  
pp. 39-51 ◽  
Author(s):  
Daniel P. Benesh ◽  
James C. Chubb ◽  
Geoff A. Parker
Keyword(s):  
Life Cycles ◽  
Complex Life Cycles

scholarly journals Community structure, life histories and secondary production of stoneflies in two small mountain streams with different degree of forest cover

2015 ◽  
Author(s):  
Pavel Beracko ◽  
Andrea Kušnírová ◽  
Michaela Partlová ◽  
Jana Ciceková
Keyword(s):  
Community Structure ◽  
Secondary Production ◽  
Life Histories ◽  
Forest Cover ◽  
Adult Emergence ◽  
Life Cycles ◽  
Mountain Streams ◽  
Annual Life Cycle ◽  
Forested Stream ◽  
The Difference

<p>Our study examines community structure and nymphal biology (life cycles and secondary production) of stoneflies in two adjacent mountain streams with different degree of forest cover in the Prosiečanka River Basin (Chočské Vrchy Mts., West Carpathians). One of the streams has non-forested catchment, converted to meadows and pastures, while the other one has catchment with 60% covered by spruce forest. Differences in forest cover and in thermal regime of the streams were reflected by the difference of stonefly communities at their structural and functional level. Species <em>Nemoura cinerea and Leuctra aurita </em>created stonefly assemblage in non-forested stream, whereas <em>Nemoura cinerea</em> also occurred in naturally forested stream together with species <em>Leuctra armata, Leuctra nigra, Leuctra prima, Siphonoperla neglecta</em> and <em>Arcynopteryx dichroa</em>. All examined species had maximally annual life cycle and in eudominant species <em>Nemoura cinerea</em> one month shift was found in nymphal hatching and adult emergence between streams. Total secondary production of stoneflies in undisturbed stream (126.46 mg DW m<sup>-2</sup> y<sup>-1</sup>) was more than two times higher than the production in non-forested stream (47.39 mg DW m<sup>-2</sup> y<sup>-1</sup>). </p>

Autonomy and integration in complex parasite life cycles

Parasitology ◽  
2016 ◽  
Vol 143 (14) ◽  
pp. 1824-1846 ◽  
Author(s):  
DANIEL P. BENESH
Keyword(s):  
Life Cycle ◽  
Holistic Approach ◽  
Life Cycles ◽  
Complex Life Cycle ◽  
Functional Specialization ◽  
Life Stages ◽  
Free Living ◽  
New Host ◽  
Complex Life Cycles ◽  
Life Cycle Stages

SUMMARYComplex life cycles are common in free-living and parasitic organisms alike. The adaptive decoupling hypothesis postulates that separate life cycle stages have a degree of developmental and genetic autonomy, allowing them to be independently optimized for dissimilar, competing tasks. That is, complex life cycles evolved to facilitate functional specialization. Here, I review the connections between the different stages in parasite life cycles. I first examine evolutionary connections between life stages, such as the genetic coupling of parasite performance in consecutive hosts, the interspecific correlations between traits expressed in different hosts, and the developmental and functional obstacles to stage loss. Then, I evaluate how environmental factors link life stages through carryover effects, where stressful larval conditions impact parasites even after transmission to a new host. There is evidence for both autonomy and integration across stages, so the relevant question becomes how integrated are parasite life cycles and through what mechanisms? By highlighting how genetics, development, selection and the environment can lead to interdependencies among successive life stages, I wish to promote a holistic approach to studying complex life cycle parasites and emphasize that what happens in one stage is potentially highly relevant for later stages.

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