scholarly journals Evidence for complex life cycle constraints on salamander body form diversification

2017 ◽  
Vol 114 (37) ◽  
pp. 9936-9941 ◽  
Author(s):  
Ronald M. Bonett ◽  
Andrea L. Blair
Keyword(s):  
Life Cycle ◽  
Phenotypic Diversity ◽  
Life Cycles ◽  
Complex Life Cycle ◽  
Body Form ◽  
Life Cycle Stages ◽  
Biphasic Life Cycle ◽  
Evolution Of Life ◽  
Adult Body ◽  
Life Cycle Evolution

Metazoans display a tremendous diversity of developmental patterns, including complex life cycles composed of morphologically disparate stages. In this regard, the evolution of life cycle complexity promotes phenotypic diversity. However, correlations between life cycle stages can constrain the evolution of some structures and functions. Despite the potential macroevolutionary consequences, few studies have tested the impacts of life cycle evolution on broad-scale patterns of trait diversification. Here we show that larval and adult salamanders with a simple, aquatic-only (paedomorphic) life cycle had an increased rate of vertebral column and body form diversification compared to lineages with a complex, aquatic-terrestrial (biphasic) life cycle. These differences in life cycle complexity explain the variations in vertebral number and adult body form better than larval ecology. In addition, we found that lineages with a simple terrestrial-only (direct developing) life cycle also had a higher rate of adult body form evolution than biphasic lineages, but still 10-fold lower than aquatic-only lineages. Our analyses demonstrate that prominent shifts in phenotypic evolution can follow long-term transitions in life cycle complexity, which may reflect underlying stage-dependent constraints.

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.

scholarly journals Rapid phenotypic evolution following shifts in life cycle complexity

2018 ◽  
Vol 285 (1871) ◽  
pp. 20172304 ◽  
Author(s):  
Ronald M. Bonett ◽  
John G. Phillips ◽  
Nicholus M. Ledbetter ◽  
Samuel D. Martin ◽  
Luke Lehman
Keyword(s):  
Life Cycle ◽  
Vertebral Column ◽  
Life Stages ◽  
Phenotypic Evolution ◽  
Trait Evolution ◽  
Life Cycle Stages ◽  
Biphasic Life Cycle ◽  
History Of ◽  
Life Cycle Evolution

Life cycle strategies have evolved extensively throughout the history of metazoans. The expression of disparate life stages within a single ontogeny can present conflicts to trait evolution, and therefore may have played a major role in shaping metazoan forms. However, few studies have examined the consequences of adding or subtracting life stages on patterns of trait evolution. By analysing trait evolution in a clade of closely related salamander lineages we show that shifts in the number of life cycle stages are associated with rapid phenotypic evolution. Specifically, salamanders with an aquatic-only (paedomorphic) life cycle have frequently added vertebrae to their trunk skeleton compared with closely related lineages with a complex aquatic-to-terrestrial (biphasic) life cycle. The rate of vertebral column evolution is also substantially lower in biphasic lineages, which may reflect the functional compromise of a complex cycle. This study demonstrates that the consequences of life cycle evolution can be detected at very fine scales of divergence. Rapid evolutionary responses can result from shifts in selective regimes following changes in life cycle complexity.

scholarly journals Rapid Turnover of Life-Cycle-Related Genes in the Brown Algae

2018 ◽  
Author(s):  
A.P. Lipinska ◽  
M.L. Serrano-Serrano ◽  
Akira F. Peters ◽  
K. Kogame ◽  
J Mark Cock ◽  
...  
Keyword(s):  
Gene Expression ◽  
Life Cycle ◽  
Brown Algae ◽  
Phenotypic Diversity ◽  
Expression Patterns ◽  
Life Cycles ◽  
Sexual Life ◽  
High Turnover ◽  
Life Cycle Stages ◽  
Eukaryotic Group

ABSTRACTBackgroundSexual life cycles in eukaryotes involve a cyclic alternation between haploid and diploid phases. While most animals possess a diploid life cycle, plants and algae alternate between multicellular haploid (gametophyte) and diploid (sporophyte) generations. In many algae, gametophytes and sporophytes are independent and free living, and may present dramatic phenotypic differences. The same shared genome can therefore be subject to different, even conflicting, selection pressures in each of the life cycle generations. Here, we have analysed the nature and extent of genome-wide generation-biased gene expression in four species of brown algae with contrasting levels of dimorphism between life cycle generations, in order to assess the potential role of generation-specific selection in shaping patterns of gene expression and divergence.ResultsWe show that the proportion of the transcriptome that is generation-biased is associated with the level of phenotypic dimorphism between the life cycle stages. Importantly, our data reveals a remarkably high turnover rate for life-cycle-related gene sets across the brown algae and highlights the importance not only of co-option of regulatory programs from one generation to the other but also a key role for newly emerged, lineage-specific genes in the evolution of the gametophyte and sporophyte developmental programs in this major eukaryotic group. Moreover, we show that generation-biased genes display distinct evolutionary modes, with gametophyte-biased genes evolving rapidly at the coding sequence level whereas sporophyte-biased genes exhibit changes in their patterns of expression.ConclusionOur analysis uncovers the characteristics, expression patterns and evolution of generation-biased genes and underline the selective forces that shape this previously underappreciated source of phenotypic diversity.

scholarly journals Probing Plasmodium falciparum sexual commitment at the single-cell level

2018 ◽  
Vol 3 ◽  
pp. 70 ◽  
Author(s):  
Nicolas M.B. Brancucci ◽  
Mariana De Niz ◽  
Timothy J. Straub ◽  
Deepali Ravel ◽  
Lauriane Sollelis ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Life Cycle ◽  
Single Cell ◽  
Transcriptional Profiling ◽  
Quantitative Imaging ◽  
Complex Life Cycle ◽  
Major Transitions ◽  
Transcriptional Signature ◽  
Life Cycle Stages ◽  
Parasite Populations

Background: Malaria parasites go through major transitions during their complex life cycle, yet the underlying differentiation pathways remain obscure. Here we apply single cell transcriptomics to unravel the program inducing sexual differentiation in Plasmodium falciparum. Parasites have to make this essential life-cycle decision in preparation for human-to-mosquito transmission. Methods: By combining transcriptional profiling with quantitative imaging and genetics, we defined a transcriptional signature in sexually committed cells. Results: We found this transcriptional signature to be distinct from general changes in parasite metabolism that can be observed in response to commitment-inducing conditions. Conclusions: This proof-of-concept study provides a template to capture transcriptional diversity in parasite populations containing complex mixtures of different life-cycle stages and developmental programs, with important implications for our understanding of parasite biology and the ongoing malaria elimination campaign.

Life Cycles

2001 ◽  
Author(s):  
Jan A. Pechenik
Keyword(s):  
Life Cycle ◽  
Genetic Material ◽  
Life Cycles ◽  
Offspring Size ◽  
Free Living ◽  
Complex Life Cycles ◽  
Volume Number ◽  
Larval Stages ◽  
Underlying Mechanisms ◽  
Life Cycle Evolution

I have a Hardin cartoon on my office door. It shows a series of animals thinking about the meaning of life. In sequence, we see a lobe-finned fish, a salamander, a lizard, and a monkey, all thinking, “Eat, survive, reproduce; eat, survive, reproduce.” Then comes man: “What's it all about?” he wonders. Organisms live to reproduce. The ultimate selective pressure on any organism is to survive long enough and well enough to pass genetic material to a next generation that will also be successful in reproducing. In this sense, then, every morphological, physiological, biochemical, or behavioral adaptation contributes to reproductive success, making the field of life cycle evolution a very broad one indeed. Key components include mode of sexuality, age and size at first reproduction (Roff, this volume), number of reproductive episodes in a lifetime, offspring size (Messina and Fox, this volume), fecundity, the extent to which parents protect their offspring and how that protection is achieved, source of nutrition during development, survival to maturity, the consequences of shifts in any of these components, and the underlying mechanisms responsible for such shifts. Many of these issues are dealt with in other chapters. Here I focus exclusively on animals, and on a particularly widespread sort of life cycle that includes at least two ecologically distinct free-living stages. Such “complex life cycles” (Istock 1967) are especially common among amphibians and fishes (Hall and Wake 1999), and within most invertebrate groups, including insects (Gilbert and Frieden 1981), crustaceans, bivalves, gastropods, polychaete worms, echinoderms, bryozoans, and corals and other cnidarians (Thorson 1950). In such life cycles, the juvenile or adult stage is reached by metamorphosing from a preceding, free-living larval stage. In many species, metamorphosis involves a veritable revolution in morphology, ecology, behavior, and physiology, sometimes taking place in as little as a few minutes or a few hours. In addition to the issues already mentioned, key components of such complex life cycles include the timing of metamorphosis (i.e., when it occurs), the size at which larvae metamorphose, and the consequences of metamorphosing at particular times or at particular sizes. The potential advantages of including larval stages in the life history have been much discussed.

scholarly journals Endocrine Control of Life-Cycle Stages: A Constraint on Response to the Environment?

The Condor ◽  
2000 ◽  
Vol 102 (1) ◽  
pp. 35-51 ◽  
Author(s):  
Jerry D. Jacobs ◽  
John C. Wingfield
Keyword(s):  
Life History ◽  
Life Cycle ◽  
Control Systems ◽  
Life Cycles ◽  
Environmental Cues ◽  
Endocrine Control ◽  
Theoretical Approaches ◽  
Life Cycle Stages ◽  
Wide Range ◽  
Breeding Seasons

Abstract Most organisms live in seasonal environments that fluctuate on a predictable schedule and sometimes unpredictably. Individuals must, therefore, adjust so as to maximize their survival and reproductive success over a wide range of environmental conditions. In birds, as in other vertebrates, endocrine secretions regulate morphological, physiological, and behavioral changes in anticipation of future events. The individual thus prepares for predictable fluctuations in its environment by changing life-cycle stages. We have applied finite-state machine theory to define and compare different life-history cycles. The ability of birds to respond to predictable and unpredictable regimes of environmental variation may be constrained by the adaptability of their endocrine control systems. We have applied several theoretical approaches to natural history data of birds to compare the complexity of life cycles, the degree of plasticity of timing of stages within the cycle, and to determine whether endocrine control mechanisms influence the way birds respond to their environments. The interactions of environmental cues on the timing of life-history stages are not uniform in all populations. Taking the reproductive life-history stage as an example, arctic birds that have short breeding seasons in severe environments appear to use one reliable environmental cue to time reproduction and they ignore other factors. Birds having longer breeding seasons exhibit greater plasticity of onset and termination and appear to integrate several environmental cues. Theoretical approaches may allow us to predict how individuals respond to their environment at the proximate level and, conversely, predict how constraints imposed by endocrine control systems may limit the complexity of life cycles.

Analysis of the juvenile shell of Lingula anatina (Brachiopoda: Linguliformea) provides insight into the evolution of life cycles of fossil brachiopods

Paleobiology ◽  
2020 ◽  
pp. 1-15
Author(s):  
Anna A. Madison ◽  
Tatyana V. Kuzmina ◽  
Elena N. Temereva
Keyword(s):  
Life Cycle ◽  
Anterior Margin ◽  
The Philippines ◽  
Life Cycles ◽  
Published Data ◽  
Egg Envelope ◽  
Evolution Of Life ◽  
The Republic ◽  
Planktotrophic Larvae ◽  
Insight Into

Abstract Inferences on the development and morphology of extinct brachiopods must be informed by the ontogeny and shell ornamentation of extant brachiopods. Although the adult shells of extant brachiopods are well studied, detailed descriptions of the embryonic and juvenile shells of extant lingulides are lacking. Here, we describe in detail the shells of juveniles of Lingula anatina Lamarck, 1801 from Vietnam and the Republic of the Philippines. The following previously unknown properties of the lingulide shell are described: (1) a distinct border between the protegulum and the brephic shell; (2) drapes that develop on both the protegulum and brephic shell; and (3) the notched anterior margin of the brephic shell. The drapes and cogs on the brephic shell may be caused by the formation of setal follicles during the planktonic stage. Specimens of L. anatina from the Philippines have larger brephic shells than those from Vietnam, probably because the former have a longer planktonic stage. Based on comparisons of the first-formed shells of extant brachiopods with published data on fossil brachiopods, we suggest that the life cycle of extant lingulides, in which planktotrophic juveniles with a shell hatch from the egg envelope, is the most evolutionarily advanced brachiopod life cycle and appeared in the early Silurian. We suggest criteria for determining the type of life cycle based on the structure of the first-formed shell of brachiopods. Finally, we consider hypothetical scenarios of life cycles of fossil brachiopods, including true planktotrophic larvae in the Cambrian linguliforms.

scholarly journals Integrating natural and sexual selection across the biphasic life cycle

2021 ◽  
Author(s):  
Craig Purchase ◽  
Jonathan Evans ◽  
Julissa Roncal
Keyword(s):  
Sexual Selection ◽  
Life Cycle ◽  
Natural Selection ◽  
Conceptual Framework ◽  
Life Cycles ◽  
Parental Effect ◽  
Biphasic Life Cycle ◽  
Evolutionary Trajectories ◽  
Taxonomic Groups ◽  
Natural And Sexual Selection

An alternation between diploid and haploid phases is universal among sexual eukaryotes. Across this biphasic cycle, natural selection and sexual selection occur in both phases. Together, these four stages of selection act on the phenotypes of individuals and influence the evolutionary trajectories of populations, but are rarely studied holistically. Here, we provide a conceptual framework that transcends taxonomic groups, and unifies the entire selection landscape within and across the diploid and haploid phases. Our synthesis produces six direct links among four selection stages, and from this we define four types of parental effect. We argue that knowledge of the complex and intertwined opportunities for selection within biphasic life cycles will offer clearer insights into key ecological and evolutionary processes, with benefits to applied science.

scholarly journals Developmental regulation of edited CYb and COIII mitochondrial mRNAs is achieved by distinct mechanisms in Trypanosoma brucei

2020 ◽  
Vol 48 (15) ◽  
pp. 8704-8723
Author(s):  
Joseph T Smith Jr. ◽  
Eva Doleželová ◽  
Brianna Tylec ◽  
Jonathan E Bard ◽  
Runpu Chen ◽  
...  
Keyword(s):  
Life Cycle ◽  
Trypanosoma Brucei ◽  
High Throughput Sequencing ◽  
Environmental Changes ◽  
Developmental Regulation ◽  
Complex Life Cycle ◽  
Mrna Levels ◽  
Developmentally Regulated ◽  
Life Cycle Stages

Abstract Trypanosoma brucei is a parasitic protozoan that undergoes a complex life cycle involving insect and mammalian hosts that present dramatically different nutritional environments. Mitochondrial metabolism and gene expression are highly regulated to accommodate these environmental changes, including regulation of mRNAs that require extensive uridine insertion/deletion (U-indel) editing for their maturation. Here, we use high throughput sequencing and a method for promoting life cycle changes in vitro to assess the mechanisms and timing of developmentally regulated edited mRNA expression. We show that edited CYb mRNA is downregulated in mammalian bloodstream forms (BSF) at the level of editing initiation and/or edited mRNA stability. In contrast, edited COIII mRNAs are depleted in BSF by inhibition of editing progression. We identify cell line-specific differences in the mechanisms abrogating COIII mRNA editing, including the possible utilization of terminator gRNAs that preclude the 3′ to 5′ progression of editing. By examining the developmental timing of altered mitochondrial mRNA levels, we also reveal transcript-specific developmental checkpoints in epimastigote (EMF), metacyclic (MCF), and BSF. These studies represent the first analysis of the mechanisms governing edited mRNA levels during T. brucei development and the first to interrogate U-indel editing in EMF and MCF life cycle stages.

Project Life-Cycle Planning and Methodologies

2003 ◽  
pp. 168-192
Author(s):  
Len Asprey ◽  
Michael Middleton
Keyword(s):  
Life Cycle ◽  
Product Development ◽  
Management Plan ◽  
Life Cycles ◽  
Successful Implementation ◽  
Project Organization ◽  
Life Cycle Stages ◽  
Project Deliverables ◽  
Life Cycle Development ◽  
Project Life

This chapter deals with the planning aspects of an IDCM project, including scope, feasibility, and life-cycle development. It reviews the typical project deliverables that may be used during planning and subsequent phases. The objectives are to consider and discuss: • The importance of planning to the successful implementation of an IDCM solution, and the need to distinguish between product development and project life-cycles; • A product development life-cycle that enterprises can use for an IDCM project; • The steps involved in initiating and defining an IDCM project; • An approach to aligning the development of a management framework with requirements for enabling an IDCM solution, including a review of key life-cycle stages; • Development of a project organization structure that may be applicable for an enterprise IDCM project; • Identification of a set of risks to form the basis of a Risk Management Plan; and • Methodologies suitable for an IDCM project.

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