Search

Age and growth-related parameters provide a better understanding of life-history adaptations and trade-offs and can be studied in the wild through capture-mark-recapture (CMR) or sclerochronology (i.e., skeletochronology and counting growth marks on hard structures). In chelonians, skeletochronology is limited to carcasses, CMR is limited by time and funding constraints, but counting shell growth annuli (SGA count) is a cheaper and faster alternative. A long-term CMR study in Testudo graeca from south-eastern Romania allowed us to compare the age estimated by the two sclerochronology methods using carcasses, and calibrate the results with data obtained from recaptured tortoises. We found that the accuracy of SGA counts significantly decreased with time (i.e., years between captures and older individuals). Skeletochronology showed the best results with long bones (i.e., ulna, radius, femur), but overall underestimated the age when compared to SGA counts; we obtained comparable results from these two methods in tortoises up to 17 years old. The oldest age estimated by skeletochronology alone was 28 years, 30 years by SGA counts, and 40 years by SGA counts when calibrated by CMR. The growth models using age estimations from both skeletochronology and SGA counts were similar, highlighting their usefulness in monitoring growth trajectories. Our study showed that while age estimation in tortoises is challenging, a combination of methods can improve its accuracy. [ABSTRACT FROM AUTHOR]

Echinoderms are a phylum of marine deterostomes with a range of interesting biological features. One remarkable ability is their impressive capacity to regenerate most of their adult tissues, including the central nervous system (CNS). The research community has accumulated data that demonstrates that, in spite of the pentaradial adult body plan, echinoderms share deep similarities with their bilateral sister taxa such as hemichordates and chordates. Some of the new data reveal the complexity of the nervous system in echinoderms. In terms of the cellular architecture, one of the traits that is shared between the CNS of echinoderms and chordates is the presence of radial glia. In chordates, these cells act as the main progenitor population in CNS development. In mammals, radial glia are spent in embryogenesis and are no longer present in adults, being replaced with other neural cell types. In non-mammalian chordates, they are still detected in the mature CNS along with other types of glia. In echinoderms, radial glia also persist into the adulthood, but unlike in chordates, it is the only known glial cell type that is present in the fully developed CNS. The echinoderm radial glia is a multifunctional cell type. Radial glia forms the supporting scaffold of the neuroepithelium, exhibits secretory activity, clears up dying or damaged cells by phagocytosis, and, most importantly, acts as a major progenitor cell population. The latter function is critical for the outstanding developmental plasticity of the adult echinoderm CNS, including physiological cell turnover, indeterminate growth, and a remarkable capacity to regenerate major parts following autotomy or traumatic injury. In this review we summarize the current knowledge on the organization and function of the echinoderm radial glia, with a focus on the role of this cell type in adult neurogenesis. [ABSTRACT FROM AUTHOR]

Echinoderms are a phylum of marine deterostomes with a range of interesting biological features. One remarkable ability is their impressive capacity to regenerate most of their adult tissues, including the central nervous system (CNS). The research community has accumulated data that demonstrates that, in spite of the pentaradial adult body plan, echinoderms share deep similarities with their bilateral sister taxa such as hemichordates and chordates. Some of the new data reveal the complexity of the nervous system in echinoderms. In terms of the cellular architecture, one of the traits that is shared between the CNS of echinoderms and chordates is the presence of radial glia. In chordates, these cells act as the main progenitor population in CNS development. In mammals, radial glia are spent in embryogenesis and are no longer present in adults, being replaced with other neural cell types. In non-mammalian chordates, they are still detected in the mature CNS along with other types of glia. In echinoderms, radial glia also persist into the adulthood, but unlike in chordates, it is the only known glial cell type that is present in the fully developed CNS. The echinoderm radial glia is a multifunctional cell type. Radial glia forms the supporting scaffold of the neuroepithelium, exhibits secretory activity, clears up dying or damaged cells by phagocytosis, and, most importantly, acts as a major progenitor cell population. The latter function is critical for the outstanding developmental plasticity of the adult echinoderm CNS, including physiological cell turnover, indeterminate growth, and a remarkable capacity to regenerate major parts following autotomy or traumatic injury. In this review we summarize the current knowledge on the organization and function of the echinoderm radial glia, with a focus on the role of this cell type in adult neurogenesis.

Abstract Background Echinoderms are a phylum of marine invertebrates with close phylogenetic relationships to chordates. Many members of the phylum Echinodermata are capable of extensive post-traumatic regeneration and life-long indeterminate growth. Different from regeneration, the life-long elongation of the main body axis in adult echinoderms has received little attention. The anatomical location and the nature of the dividing progenitor cells contributing to adults’ growth is unknown. Results We show that the proliferating cells that drive the life-long growth of adult brittle star arms are mostly localized to the subterminal (second from the tip) arm segment. Each of the major anatomical structures contains dividing progenitors. These structures include: the radial nerve, water-vascular canal, and arm coelomic wall. Some of those proliferating progenitor cells are capable of multiple rounds of cell division. Within the nervous system, the progenitor cells were identified as a subset of radial glial cells that do not express Brn1/2/4, a transcription factor with a conserved role in the neuronal fate specification. In addition to characterizing the growth zone and the nature of the precursor cells, we provide a description of the microanatomy of the four distal-most arm segments contrasting the distal with the proximal segments, which are more mature. Conclusions The growth of the adult brittle star arms occurs via proliferation of progenitor cells in the distal segments, which are most abundant in the second segment from the tip. At least some of the progenitors are capable of multiple rounds of cell division. Within the nervous system the dividing cells were identified as Brn1/2/4-negative radial glial cells.

Artemisia tridentata ssp. tridentata is a tall perennial native shrub that occurs widely over many western states. Stems exhibit a regular pattern in which numerous stem terminal shoots elongate rapidly in spring and early summer while many vegetative stem terminal branches eventually produce flowers and seeds in late autumn. Stem samples were taken from June to November, 2015. Prior to August 7, most stem terminals only had leaves on branches (vegetative stem terminals). As the season progressed, vegetative stem terminals produced flowers (reproductive stem terminals). Stem terminals that eventually produce flowers and seeds are determinate and die at the end of the growing season. However, if stem terminals produce at least one vegetative branch, these vegetative (indeterminate) branches may remain alive, potentially elongating the following year. For 18 stem terminal samples collected from August 7 to November 23, only three stem terminals were indeterminate. All other stem terminals were determinate. Xylem conductivities, at the junction of the 2015 stem terminals and 2014 growth, were similar at nearly 1.3 g cm MPa–1 s–1. In contrast, mean xylem conductivities, at stem terminals of indeterminate and determinate stem terminals, were 0.149 and 0.0015 g cm MPa–1 s–1, respectively. The high xylem conductivities for stem terminals of indeterminate stem terminals coincide with actively growing stem terminals, while the lower xylem conductivities for stem terminals of determinate stem terminals coincide with eventual death of these stem terminals. [ABSTRACT FROM AUTHOR]

The origin, incidence, and consequences of reproductive senescence vary greatly across the tree of life. In vertebrates, research on reproductive senescence has been mainly focused on mammals and birds, demonstrating that its variation is largely linked to critical life history traits, such as growth patterns, juvenile, and adult mortality, and reproductive strategy. Fishes represent half of the vertebrate taxonomic diversity and display remarkable variation in life history. Based on a thorough literature review, we summarize current evidence on reproductive senescence in ray-finned fishes (Actinopterygii). While survival and physiological senescence are acknowledged in fish, their potential age-related reproductive decline has often been disregarded due to the prevalence of indeterminate growth. We demonstrate that age-related reproductive decline is reported across fish phylogeny, environments, and traits. An important point of our review is that the incidence of reproductive senescence in a species depends on both the number of studies for that species and the coverage of its maximum lifespan by the study. Reproductive senescence was documented for one-third of the studied fish species, with females suffering an age-related decline in reproductive traits less often than males or both parents combined. Neither parental care nor migratory strategy corresponded with the occurrence of reproductive senescence in fish. The traits that were affected by reproductive senescence most often were sex-specific, with pre-mating and mating categories of traits declining in females and sperm quality and quantity in males. We also demonstrate that reproductive senescence can be buffered by indeterminate growth. We provide rich evidence of reproductive senescence across ray-finned fishes, but we highlight the need for better data on age-related reproduction in fishes.

One-leaf plants in the Gesneriaceae family initially have two cotyledons of identical size; one cotyledon stops growing shortly after germination, whereas the other continues indeterminate growth. Factors involved in the unequal growth have been investigated, and a competitive relationship between the two cotyledons was previously proposed. However, questions regarding the fate determination of the two cotyledons remain: Why does only one cotyledon grow indeterminately while the other stops; is the fate of the cotyledons reversible; and what role does light quality play in the fate determination of the cotyledons? In this study, physiological experiments using the one-leaf plant species Monophyllaea glabra suggest that a biased auxin concentration between the two cotyledons and subsequent cytokinin levels may determine the fate of the cotyledons. In addition, observation of relatively mature individuals without hormone treatment and younger individuals with cytokinin treatment under laboratory growth conditions revealed that the fate determination of the microcotyledon is reversible. Although light quality has been suggested to be important for the determination of cotyledon fate in Streptocarpus rexii, an anisocotylous species, we conclude that light quality is not important in M. glabra. [ABSTRACT FROM AUTHOR]

Background: Echinoderms are a phylum of marine invertebrates with close phylogenetic relationships to chordates. Many members of the phylum Echinodermata are capable of extensive post-traumatic regeneration and life-long indeterminate growth. Different from regeneration, the life-long elongation of the main body axis in adult echinoderms has received little attention. The anatomical location and the nature of the dividing progenitor cells contributing to adults' growth is unknown. Results: We show that the proliferating cells that drive the life-long growth of adult brittle star arms are mostly localized to the subterminal (second from the tip) arm segment. Each of the major anatomical structures contains dividing progenitors. These structures include: the radial nerve, water-vascular canal, and arm coelomic wall. Some of those proliferating progenitor cells are capable of multiple rounds of cell division. Within the nervous system, the progenitor cells were identified as a subset of radial glial cells that do not express Brn1/2/4, a transcription factor with a conserved role in the neuronal fate specification. In addition to characterizing the growth zone and the nature of the precursor cells, we provide a description of the microanatomy of the four distal-most arm segments contrasting the distal with the proximal segments, which are more mature. Conclusions: The growth of the adult brittle star arms occurs via proliferation of progenitor cells in the distal segments, which are most abundant in the second segment from the tip. At least some of the progenitors are capable of multiple rounds of cell division. Within the nervous system the dividing cells were identified as Brn1/2/4-negative radial glial cells. [ABSTRACT FROM AUTHOR]

Abstract Post‐maturation growth leading to indeterminate growth patterns is widespread in nature. However, its adaptive value is unclear. Life history theory suggests this allocation strategy may be favored by temporal pulses in the intensity of mortality and/or the capacity to produce new tissues. Addressing the origin of indeterminate growth and the variability of growth patterns, we studied the growth of duck mussels, Anodonta anatina, a pan‐European unionid, in 18 Polish lakes. For each population, the sex, size, and age of collected mussels were measured to estimate Bertalanffy's growth curve parameters. We integrated information on A. anatina mortality rates, lake trophy, biofouling by zebra mussels, Dreissena polymorpha, and the prevalence of parasitic trematode larvae to identify selective conditions in lakes. We found two sources of mortality in A. anatina populations, pertaining to adverse effects of zebra mussel biofouling and trophy state on mussel survival. Additionally, populations with heavier biofouling presented a smaller abundance of parasites, indicative of a relationship between filtering intensity and contraction of water‐borne trematode larvae by filtering A. anatina. Consistently for each sex, populations with a greater trophy‐related mortality were characterized in A. anatina by a smaller asymptotic size Lmax, indicative of a life history response to mortality risk involving early maturation at a smaller body size. In all populations, females featured higher mortality and larger asymptotic size versus males. Our findings support a theoretical view that adaptive responses to selection involve adjustments in the lifetime resource allocation patterns. These adjustments should be considered drivers of the origin of indeterminate growth strategy in species taking parental care by offspring brooding in body cavities.

We considered how environmental variation and adaption together constrain energy acquisition of a keystone predator and how the constraints might influence its ecological function. We tested the proposition that changing energy availability, occurring as shifts in shore level and size composition of the lower vertical boundary of intertidal mussel beds (Mytilus spp.), affects energy storage and growth of predatory sea stars, Pisaster ochraceus. Energy storage of Pisaster (mass of the pyloric caeca, PC) increased when highly variable inter‐annual mussel recruitment temporarily shifted the lower boundary of the mussel bed down‐shore; energy storage decreased when the lower boundary receded up‐shore. Greatest storage occurred during massive recruitment of juvenile mussels, which caused the largest downward extensions of the boundary. To test the causal basis of the storage–boundary correlation, sea stars collected from sites with natural episodes of massive mussel recruitment were tagged and translocated to sites with experimentally shifted boundaries. On mussel beds with lower boundaries artificially expanded downward, the sea stars sustained high energy storage over most of the range of initial sizes. On mussel beds left unaltered or experimentally recessed, they lost PC mass. The amounts of loss were similar between unaltered and recessed treatments. We suggest an explanation for this unexpected similarity. Pisaster aggregate and disperse in response to the inter‐annual variation in mussel recruitment, and this numerical response is integral to mechanisms holding stationary the lower boundary, imposing stability on the local mussel population. Inter‐annual episodes of massive mussel recruitment, which have the potential to abruptly destabilize the lower boundaries, (1) elicit the strongest numerical response and (2) incur the greatest energy storage. The amount of energy storage in the season of active foraging is approximately proportional to the reproductive output in the subsequent reproductive season. Therefore, we propose that the system property of prey population stability originates in energy constraints underpinning Darwinian fitness of a keystone predator. Study limitations and further tests of the hypothesis are described. [ABSTRACT FROM AUTHOR]

Leatherback marine turtles are the largest extant turtles with some individuals measuring up to 2 m in carapace length. In addition, this species remains in oceanic habitat during much its life, making it difficult to investigate its ontogeny from hatchling to adult stage. Furthermore, distinct chondro‐osseous (cartilage and bone) tissue morphology has led to speculation that sexual maturity may be reached as early as 3 years while others have estimated a minimum of 25 years to reach adulthood. Using a combination of reanalysis of the growth trajectories of juveniles maintained in captivity, and the age–size relationship of individuals in the field, we demonstrate and quantify the indeterminate growth of this species. Using comparisons of female size distribution on nesting beaches and stranded or captured‐at‐sea size distributions adjusted with a new asymmetric sigmoid function, we were able to model the size reaction norm for female sexual maturity. Combining these two models, we show that some females may reach maturity at 14 years in natural conditions, while others will take 50 years or more. Sexual maturity may even be reached at 5 years when individuals experience exceptionally good environmental conditions. This extreme plasticity in the age of sexual maturity has been demonstrated in loggerhead turtles in natural conditions and in green turtles in captivity. It may be a general life‐history feature of marine turtles. [ABSTRACT FROM AUTHOR]

Abstract We considered how environmental variation and adaption together constrain energy acquisition of a keystone predator and how the constraints might influence its ecological function. We tested the proposition that changing energy availability, occurring as shifts in shore level and size composition of the lower vertical boundary of intertidal mussel beds (Mytilus spp.), affects energy storage and growth of predatory sea stars, Pisaster ochraceus. Energy storage of Pisaster (mass of the pyloric caeca, PC) increased when highly variable inter‐annual mussel recruitment temporarily shifted the lower boundary of the mussel bed down‐shore; energy storage decreased when the lower boundary receded up‐shore. Greatest storage occurred during massive recruitment of juvenile mussels, which caused the largest downward extensions of the boundary. To test the causal basis of the storage–boundary correlation, sea stars collected from sites with natural episodes of massive mussel recruitment were tagged and translocated to sites with experimentally shifted boundaries. On mussel beds with lower boundaries artificially expanded downward, the sea stars sustained high energy storage over most of the range of initial sizes. On mussel beds left unaltered or experimentally recessed, they lost PC mass. The amounts of loss were similar between unaltered and recessed treatments. We suggest an explanation for this unexpected similarity. Pisaster aggregate and disperse in response to the inter‐annual variation in mussel recruitment, and this numerical response is integral to mechanisms holding stationary the lower boundary, imposing stability on the local mussel population. Inter‐annual episodes of massive mussel recruitment, which have the potential to abruptly destabilize the lower boundaries, (1) elicit the strongest numerical response and (2) incur the greatest energy storage. The amount of energy storage in the season of active foraging is approximately proportional to the reproductive output in the subsequent reproductive season. Therefore, we propose that the system property of prey population stability originates in energy constraints underpinning Darwinian fitness of a keystone predator. Study limitations and further tests of the hypothesis are described.

Post‐maturation growth leading to indeterminate growth patterns is widespread in nature. However, its adaptive value is unclear. Life history theory suggests this allocation strategy may be favored by temporal pulses in the intensity of mortality and/or the capacity to produce new tissues.Addressing the origin of indeterminate growth and the variability of growth patterns, we studied the growth of duck mussels, Anodonta anatina, a pan‐European unionid, in 18 Polish lakes. For each population, the sex, size, and age of collected mussels were measured to estimate Bertalanffy's growth curve parameters. We integrated information on A. anatina mortality rates, lake trophy, biofouling by zebra mussels, Dreissena polymorpha, and the prevalence of parasitic trematode larvae to identify selective conditions in lakes.We found two sources of mortality in A. anatina populations, pertaining to adverse effects of zebra mussel biofouling and trophy state on mussel survival. Additionally, populations with heavier biofouling presented a smaller abundance of parasites, indicative of a relationship between filtering intensity and contraction of water‐borne trematode larvae by filtering A. anatina.Consistently for each sex, populations with a greater trophy‐related mortality were characterized in A. anatina by a smaller asymptotic size Lmax, indicative of a life history response to mortality risk involving early maturation at a smaller body size. In all populations, females featured higher mortality and larger asymptotic size versus males.Our findings support a theoretical view that adaptive responses to selection involve adjustments in the lifetime resource allocation patterns. These adjustments should be considered drivers of the origin of indeterminate growth strategy in species taking parental care by offspring brooding in body cavities. [ABSTRACT FROM AUTHOR]

Reproductive senescence is an age‐associated decline in reproductive performance, which often arises as a trade‐off between current and future reproduction. Given that mortality is inevitable, increased allocation into current reproduction is favoured despite costs paid later in life.This assumption is violated in organisms with post‐maturity growth whose reproductive output increases long after maturity. While reproductive senescence is frequently studied in animals with determinate growth at maturity, such as insects or mammals, we have very limited understanding of reproductive senescence in organisms with an extensive post‐maturity growth period.The fact that many post‐maturity growers experience strong adult mortality leads to conflicting expectations for reproductive senescence. The aim of this study was to investigate how co‐occurrence of rapid life history and post‐maturity growth mould reproductive senescence in a short‐lived killifish, Nothobranchius furzeri, using longitudinal data on laboratory and wild‐type populations.We followed the individual fecundity, fertility and fertilization of 132 singly housed fish from the perspectives of chronological and biological age. At the onset of senescence, the sex‐specific contribution to decrease in fertilization capacity was investigated. Allocation trade‐offs were estimated through the association between reproductive parameters and life span, and between early‐life and late‐life fecundity.We demonstrate that female fecundity increased steadily after maturity and reproductive senescence occurred long after the growth asymptote. The prime age for fecundity coincided with 50% female survival and consequent decline in fecundity implies an association with somatic deterioration. Reproductive senescence in fertilization rate was stronger in females than in males. Females with high early fecundity experienced a long life span and high late‐life fecundity, discounting the role of allocation trade‐offs in reproductive senescence.The present study reports a clear case of reproductive senescence in a fish with a long post‐maturation growth period, unusually rapid development and short life span. The onset of reproductive senescence was postponed compared to animals that cease growing at sexual maturity. Fish and other animals with post‐maturity growth have long been considered insusceptible to ageing but this conclusion may be related to the previous lack of longitudinal data rather than to the absence of reproductive senescence in such organisms. [ABSTRACT FROM AUTHOR]

Members of the genus Monophyllaea are unique in that they produce no new organ during the vegetative phase in the shoot; instead, one of the cotyledons grows indeterminately. The mechanism of this unique trait is unclear, in part because of the lack of suitable assessment techniques. We therefore established a whole-mount in situ hybridization technique, a powerful means of examining spatial patterns in gene expression, for Monophyllaea glabra. By using this, we examined the expression pattern of a SHOOT MERISTEMLESS (STM) ortholog, which is indispensable for the formation and maintenance of the shoot apical meristem (SAM) in typical angiosperms. Expression was confined to the groove meristem (GM), which corresponds to the SAM. We also assessed the expression pattern of ANGUSTIFOLIA3 (AN3), a key promoter for cell division in the leaf meristem. It was expressed not only in the basal meristem (BM) tissue with active cell division in the basal part of the growing cotyledon but also in the GM. The findings suggest that the unusual gene expression pattern of the GM underpins the fuzzy morphogenesis of Monophyllaea.

Climbing plants are being increasingly viewed as models for bioinspired growing robots capable of spanning voids and attaching to diverse substrates. We explore the functional traits of the climbing cactus Selenicereus setaceus (Cactaceae) from the Atlantic forest of Brazil and discuss the potential of these traits for robotics applications. The plant is capable of growing through highly unstructured habitats and attaching to variable substrates including soil, leaf litter, tree surfaces, rocks, and fine branches of tree canopies in wind-blown conditions. Stems develop highly variable cross-sectional geometries at different stages of growth. They include cylindrical basal stems, triangular climbing stems and apical star-shaped stems searching for supports. Searcher stems develop relatively rigid properties for a given cross-sectional area and are capable of spanning voids of up to 1 m. Optimization of rigidity in searcher stems provide some potential design ideas for additive engineering technologies where climbing robotic artifacts must limit materials and mass for curbing bending moments and buckling while climbing and searching. A two-step attachment mechanism involves deployment of recurved, multi-angled spines that grapple on to wide ranging surfaces holding the stem in place for more solid attachment via root growth from the stem. The cactus is an instructive example of how light mass searchers with a winged profile and two step attachment strategies can facilitate traversing voids and making reliable attachment to a wide range of supports and surfaces.

Body growth is typically thought to be indeterminate in ectothermic vertebrates. Indeed, until recently, this growth pattern was considered to be ubiquitous in ectotherms. Our recent observations of a complete growth plate cartilage (GPC) resorption, a reliable indicator of arrested skeletal growth, in many species of lizards clearly reject the ubiquity of indeterminate growth in reptiles and raise the question about the ancestral state of the growth pattern. Using X-ray micro-computed tomography (µCT), here we examined GPCs of long bones in three basally branching clades of squamate reptiles, namely in Gekkota, Scincoidea and Lacertoidea. A complete loss of GPC, indicating skeletal growth arrest, was the predominant finding. Using a dataset of 164 species representing all major clades of lizards and the tuataras, we traced the evolution of determinate growth on the phylogenetic tree of Lepidosauria. The reconstruction of character states suggests that determinate growth is ancestral for the squamate reptiles (Squamata) and remains common in the majority of lizard lineages, while extended (potentially indeterminate) adult growth evolved several times within squamates. Although traditionally associated with endotherms, determinate growth is coupled with ectothermy in this lineage. These findings combined with existing literature suggest that determinate growth predominates in both extant and extinct amniotes. [ABSTRACT FROM AUTHOR]

Reproductive senescence is the decrease of reproductive performance with increasing age and can potentially include trans‐generational effects as the offspring produced by old parents might have a lower fitness than those produced by young parents. This negative effect may be caused either by the age of the father, mother or the interaction between the ages of both parents. Using the common woodlouse Armadillidium vulgare, an indeterminate grower, as a biological model, we tested for the existence of a deleterious effect of parental age on fitness components. Contrary to previous findings reported from vertebrate studies, old parents produced both a higher number and larger offspring than young parents. However, their offspring had lower fitness components (by surviving less, producing a smaller number of clutches or not reproducing at all) than offspring born to young parents. Our findings strongly support the existence of trans‐generational senescence in woodlice and contradict the belief that old individuals in indeterminate growers contribute the most to recruitment and correspond thereby to the key life stage for population dynamics. Our work also provides rare evidence that the trans‐generational effect of senescence can be stronger than direct reproductive senescence in indeterminate growers. [ABSTRACT FROM AUTHOR]

Members of the genus Monophyllaea are unique in that they produce no new organ during the vegetative phase in the shoot; instead, one of the cotyledons grows indeterminately. The mechanism of this unique trait is unclear, in part because of the lack of suitable assessment techniques. We therefore established a whole-mount in situ hybridization technique, a powerful means of examining spatial patterns in gene expression, for Monophyllaea glabra. By using this, we examined the expression pattern of a SHOOT MERISTEMLESS (STM) ortholog, which is indispensable for the formation and maintenance of the shoot apical meristem (SAM) in typical angiosperms. Expression was confined to the groove meristem (GM), which corresponds to the SAM. We also assessed the expression pattern of ANGUSTIFOLIA3 (AN3), a key promoter for cell division in the leaf meristem. It was expressed not only in the basal meristem (BM) tissue with active cell division in the basal part of the growing cotyledon but also in the GM. The findings suggest that the unusual gene expression pattern of the GM underpins the fuzzy morphogenesis of Monophyllaea. [ABSTRACT FROM AUTHOR]

In many annual plants, mollusks, crustaceans and ectothermic vertebrates, growth accompanies reproduction. The growth curves of these organisms often exhibit a complex shape, with episodic cessations or accelerations of growth occurring long after maturation. The mixed allocation to growth and reproduction has poorly understood adaptive consequences, and the life‐history theory does not explain if complex growth in short‐lived organisms can be adaptive.We model the trade‐off between growth and reproduction in a short‐lived organism evolving in a metapopulation. Individuals occupy risky or safe sites throughout their lives, but are uncertain regarding the risk of death. Modelled organisms are allowed to grow and produce offspring at specified time points (moults), although we also consider scenarios that approximate continuous growth and reproduction.Certain combinations of risky to safe sites select for strategies with mixed allocation to growth and reproduction that bet‐hedge offspring production in safe and risky sites. Our model shows that spatially heterogeneous environments select for mixed allocation only if safe sites do not become the prevailing source of recruits, for example, when risky sites are frequent. In certain conditions, growth curves are multi‐phasic, with allocation to growth that stops, remains constant or accelerates during adult life. The resulting complex growth curves are more likely to evolve in short‐lived organisms that moult several times per adult life.Our work shows that spatial heterogeneity can select for growth that accompanies reproduction and provides insights into the adaptive significance of complex growth curves. Short‐lived crustaceans are particularly predisposed to exhibit complex growth patterns as an adaptive response to spatially heterogeneous environments. Our results suggest that standard statistical growth models assuming adult growth rate to only decelerate over life are not well suited to approximate growth curves of short‐lived crustaceans. A free Plain Language Summary can be found within the Supporting Information of this article. [ABSTRACT FROM AUTHOR]

Indeterminate root growth depends on the stem cell niche (SCN) and root apical meristem (RAM) maintenance whose regulation permits plasticity in root system formation. Using a forward genetics approach, we isolated the moots koom1 ('short root' in Mayan) mutant that shows complete primary RAM exhaustion and abolished SCN activity. We identified that this phenotype is caused by a point mutation in the METHIONINE OVERACCUMULATOR2 (MTO2) gene that encodes THREONINE SYNTHASE1 and renamed the mutant as mto2-2. The amino acid profile showed drastic changes, most notorious of which was accumulation of methionine. In non-allelic mto1-1 (Arabidopsis thaliana cystathionine gamma-synthetase1) and mto3-1 (S-adenosylmethionine synthetase) mutants, both with an increased methionine level, the RAM size was similar to that of the wild type, suggesting that methionine overaccumulation itself did not cause RAM exhaustion in mto2 mutants. When mto2-2 RAM is not yet completely exhausted, exogenous threonine induced de novo SCN establishment and root growth recovery. The threonine-dependent RAM re-establishment in mto2-2 suggests that threonine is a limiting factor for RAM maintenance. In the root, MTO2 was predominantly expressed in the RAM. The essential role of threonine in mouse embryonic stem cells and in RAM maintenance suggests that common regulatory mechanisms may operate in plant and animal SCN maintenance. [ABSTRACT FROM AUTHOR]

The aerial part of seed plants is called the shoot, which is composed of stems, leaves, and axial buds. These are produced by indeterminate activity in the shoot apical meristem (SAM), whereas the morphogenesis of leaves depends on determinate activity of leaf meristems. However, one‐leaf plants in the Gesneriaceae family (eudicots) do not have a typical SAM and do not produce new organs when in the vegetative phase. Instead, they have one cotyledon whose growth is indeterminate. This peculiar development is supported by the groove meristem, which corresponds to the canonical SAM, and the basal meristem, which corresponds to the typical leaf meristem. However, the former does not produce any organ and the latter is active indeterminately. Gene expression and physiological analyses have been conducted in an effort to determine the molecular nature of this peculiar organogenesis. This review summarizes the current understanding of the development of one‐leaf plants to provide future perspectives in this field of research. One‐leaf plants in the Gesneriaceae family are very unique in development: do not have a typical shoot apical meristem and do not produce new organs when in the vegetative phase. This review summarizes the current understanding of the development of one‐leaf plants to provide future perspectives in this field of research. [ABSTRACT FROM AUTHOR]

The muscle phenotype of fish is regulated by numerous factors that, although widely explored, still need to be fully understood. In this context, several studies aimed to unravel how internal and external stimuli affect the muscle growth of these vertebrates. The pacu (Piaractus mesopotamicus) is a species of indeterminate muscular growth that quickly reaches high body weight. For this reason, it adds great importance to the productive sector, along with other round fish. In this context, we aimed to compile studies on fish biology and skeletal muscle growth, focusing on studies by our research group that used pacu as an experimental model along with other species. Based on these studies, new muscle phenotype regulators were identified and explored in vivo, in vitro, and in silico studies, which strongly contribute to advances in understanding muscle growth mechanisms with future applications in the productive sector. [Display omitted] • Piaractus mesopotamicus , pacu has indeterminate muscle growth pattern. • Muscle growth in Piaractus mesopotamicus , pacu is regulated by external and internal factors. • In silico analyses revealed new genes that regulate indeterminate fish muscle growth. • Understanding indeterminate fish muscle growth mechanisms may help to provide new insight to optimize finfish production [ABSTRACT FROM AUTHOR]

The type of stem growth in soybean is a distinguishing feature of cultivars. The genes Dt1 and Dt2 affect the termination of the stem, and the types of growth are classified as determinate, semi-determinate and indeterminate. Phenotypic characterization of the type of growth is complex and is occasionally erroneously described. The objective of this study was to map and validate molecular markers to classify the type of soybean growth to facilitate the description of cultivars and genotypic selection. Two populations were used for mapping and validation of molecular markers F2:3: T 117 (semi-determinate growth type) x Igra RA 518 RR (indeterminate growth type) and CD 235RR (determinate growth type) x Igra RA 518 RR. The study demonstrates that the association of the molecular marker with the gene GmTFL1b was efficient in the classification of soybean growth types. The marker sat_064 is connected to the Dt2 gene, which is located in the Liaison Group G of the consensus map of soybeans with a recombination frequency of 19.4%. Molecular markers for Dt1 and Dt2 genes efficiently described the genotypes of soybean stem growth and selection.

In isopods, parental care takes the form of offspring brooding in marsupial pouches. Marsupial brooding was an important step towards the origin of terrestrial lifestyles among isopods, but its potential role in shaping isopod life histories remains unknown. It is here considered that marsupial brooding imposes costs and creates a temporary association between the survival of mothers and that of their offspring. Integrating findings from different life history models, we predicted that the effects of marsupial brooding set selective conditions for the continuation of growth after maturation, which leads to indeterminate growth, and the production of larger offspring by larger females. Based on this perspective, a study on the size dependence of offspring production in the woodlouse Porcellio scaber was performed and the generality of the results was tested by reviewing the literature on offspring production in other isopods. In P. scaber and almost all the other studied isopods, clutch size is positively related to female size. Such dependence is a necessary pre-condition for the evolution of indeterminate growth. The body mass of P. scaber differed six-fold between the largest and smallest brooding females, indicating a high potential for post-maturation growth. Our review showed that offspring size is a rarely studied trait in isopods and that it correlates negatively with offspring number but positively with female size in nearly half of the studied species. Our study of P. scaber revealed similar patterns, but the positive effect of female size on offspring size occurred only in smaller broods, and the negative relation between clutch size and offspring size occurred only in larger females. We conclude that the intraspecific patterns of offspring production in isopods agree with theoretical predictions regarding the role of offspring brooding in shaping the adaptive patterns of female investment in growth, reproduction, and the parental care provided to individual offspring. [ABSTRACT FROM AUTHOR]

Trade-offs in energy allocation between growth, reproduction, and survival are at the core of life-history theory. While agespecific mortality is considered to be the main determinant of the optimal allocation, some life-history strategies, such as delayed or skipped reproduction, may be better understood when also accounting for reproduction costs. Here, we present a two-pool indeterminate grower model that includes survival and energetic costs of reproduction. The energetic cost sets a minimum reserve required for reproduction, while the survival cost reflects increased mortality from low postreproductive body condition. Three life-history parameters determining agedependent energy allocation to soma, reserve, and reproduction are optimized, and we show that the optimal strategies can reproduce realistic emergent growth trajectories, maturation ages, and reproductive outputs for fish. The model predictsmaturation phase shifts along the gradient of condition-related mortality and shows that increased harvesting will select for earlier maturation and higher energy allocation to reproduction. However, since the energetic reproduction cost sets limits on how early an individual can mature, an increase in fitness at high harvesting can only be achieved by diverting most reserves into reproduction. The model presented here can improve predictions of life-history responses to environmental change and human impacts because key life-history traits such as maturation age and size, maximum body size, and size-specific fecundity emerge dynamically. [ABSTRACT FROM AUTHOR]

The long tradition of common bean (Phaseolus vulgaris L.) cultivation in Croatia has resulted in the development of many landraces, which create a valuable basis for screening different physiological traits. Studying gas exchange parameters could provide valuable information that could be useful in creating new crop germplasm with enhanced agronomic attributes. Variability of gas exchange parameters, such as the net photosynthetic rate (A), transpiration rate (E), stomatal conductance (gs), intercellular CO2 concentration (Ci), light use efficiency (LUE), and water use efficiency (WUE) were studied on the collection of 226 common bean accessions and the relationship of the gas exchange parameters with the origin and morphological traits was tested. The highest variability among all landraces was found for the WUE and gs, and lowest for the A and LUE traits, indicating high potential of these traits to be used for selection and breeding programs. Accessions of the Mesoamerican origin had higher A and LUE and lower Ci values compared to accessions of the Andean origin. Accessions with the determinate growth had higher gs and Ci values and lower A, LUE and WUE values compared to accessions with the indeterminate growth. The variance components analysis showed that the growth type has a more pronounced effect on gs, Ci and WUE, whereas the origin has a stronger impact on A and LUE. The principal component analysis (PCA) showed that A separates accessions according to their origin, whereas Ci separates accessions according to their growth type. Accessions with higher Ci had lower A, indicating possibly higher rates of carboxylation per active site on the enzyme and/or higher regeneration capacity of Ribulose-1,5-bisphosphate (RuPB) in the Calvin cycle in accession with high A. [ABSTRACT FROM AUTHOR]

Amaranth (Amaranthus hypochondriacus L.) is important for its high protein content, as the nutritional value of its grain is due partly to the amount of protein higher than that of other cereals. Grains form in the inflorescences and their architecture depend on whether growth is determinate or indeterminate. By means of scanning electron microscopy and thinning techniques, we obtained images of the morphological changes of the apical meristem during the life cycle of the plant. That tissue remained undifferentiated in the indeterminate phenotype and the inflorescence was spiked, the apical meristem stopped its activity with the formation of each terminal flower, originating a synchronized development. The development of the inflorescence in determinate growth did not present phenological overlap. The branches of this last phenotype were shorter. The seeds of plants with determinate growth were heavier than those of indeterminate growth. The study of apical meristem morphology could be the basis for the analysis of morphogenetic aspects of development, which at the same time are support for the genetic improvement and agronomic management of A. hypochondriacus. [ABSTRACT FROM AUTHOR]

Copyright of Nativa is the property of Revista Nativa and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the present study, we aimed to characterize the life history of the land snail Subulina octona integrating information on lifehistory traits and morphology. We also compared the histology of the free-oviduct and spermoviduct of ovoviviparous and eggretaining species of subulinids. We considered as ovoviviparous the species in which the complete embryonic development as well as egg hatching occurs inside the parent's body and, at the end of this process, the parent releases juveniles instead of eggs. We considered as egg-retaining the species in which a great part of the embryonic development takes place inside the parent's body and the eggs laid contain well-developed embryos. The results showed that the free-oviduct of both ovoviviparous and eggretaining species shows a histological arrangement that confers greater strength to its walls and is probably related to egg retention. The wall of the spermoviduct is formed by pseudostratified columnar epithelium, with cell apical processes (probably cilia), and by underlying secretory cells. In gravid egg-retaining snails, the eggshells appear in close contact with the secretory cells of the spermoviduct. This fact suggests that these cells play a role in eggshell formation. The present study is the first account for histological features of S. octona, Allopeas gracile and Allopeas micra. The life history of S. octona is a combination of long lifespan, early sexual maturity, indeterminate growth and egg retention. Egg retention limits the number of young that can be produced in one reproductive event. However, the reproductive strategy adopted by S. octona, associating egg retention and K-strategism, compensates this cost of retaining eggs, because the reproductive success may be enhanced as a result of the higher survival of juveniles and the possibility of performing several reproductive events during the year. [ABSTRACT FROM AUTHOR]

Cucumber is an important vegetable with indeterminate growth habit which is beneficial to its yield. In this study, we cloned the TFL1 homolog CsTFL1b in cucumber. CsTFL1b shares highly sequence similarity to TFL1 from Arabidopsis and has conservative histidine amino acid residue which is necessary for TFL1 function. However, phylogenetic analysis suggested that cucurbits TFL1s (CsTFL1b of cucumber and CmTFL1 of melon) formed a subclade which is far from the AtTFL1 in Arabidopsis or CEN in Antirrhinum . CsTFL1b was highest expressed in male flower but barely expressed in SAM which was different from TFL1 in Arabidopsis with highly transcription accumulation in SAM and CsTFL1b was located in nucleus and cytoplasm. Upon ectopic expression of CsTFL1b in Arabidopsis , the flowering time of transgenic plants was significantly delayed in both wild type and tfl1-11 mutant background but the terminal flower phenotype of tfl1-11 mutant was partially rescued. These results may underlie the discrepant function of CsTFL1b in cucumber from that in Arabidopsis . [ABSTRACT FROM AUTHOR]

ABSTRACT: Hydra is emerging as a model organism for studies of ageing in early metazoan animals, but reef corals offer an equally ancient evolutionary perspective as well as several advantages, not least being the hard exoskeleton which provides a rich fossil record as well as a record of growth and means of ageing of individual coral polyps. Reef corals are also widely regarded as potentially immortal at the level of the asexual lineage and are assumed not to undergo an intrinsic ageing process. However, putative molecular indicators of ageing have recently been detected in reef corals. While many of the large massive coral species attain considerable ages (>600 years) there are other much shorter‐lived species where older members of some populations show catastrophic mortality, compared to juveniles, under environmental stress. Other studies suggestive of ageing include those demonstrating decreased reproduction, increased susceptibility to oxidative stress and disease, reduced regeneration potential and declining growth rate in mature colonies. This review aims to promote interest and research in reef coral ageing, both as a useful model for the early evolution of ageing and as a factor in studies of ecological impacts on reef systems in light of the enhanced effects of environmental stress on ageing in other organisms. [ABSTRACT FROM AUTHOR]

Juvenile growth strongly impacts life-history traits during adulthood. Yet, in juveniles with delayed maturity, elusiveness has hindered age-specific studies of growth, precluding any detailed research on its consequences later in life. Different complex growth patterns have been extracted from captive animals, suggesting species-specific trajectories occur in free-ranging animals. How pronounced are growth and body size variation (VBS) throughout a long-lived ectotherm’s life? Is VBS constant among age classes prior to maturity, or do compensatory and/or cumulative effects driven by long-lived-animal-specific strategies create distinct VBS cohorts, to ensure survival? To tackle the issue, we modelled growth data from continuous and dense annual capture-mark-recapture sampling (5096 body measurements of 1134 free-ranging individuals) of both immature and mature, long-lived Hermann’s tortoises. We analysed population, cohort, and individual-based growth and VBS. Growth ring inferred ages were cross validated with annual recaptures in 289 juveniles. Analyses unravelled an S-shaped growth curve and identified three age cohorts across which VBS increases in a step-wise manner. Neonate-specific constraints and compensatory effects seem to control VBS until 4 years of age, possibly promoting survival with size. Subsequently, a hardened carapace takes over and cumulative effects fuelled by faster growth progressively increase VBS. Whereas ungulates are in a hurry to attain adult size before growth ceases (minimizing VBS), indeterminately growing tortoises can shape individual asymptotic sizes even after growth decelerates. Tortoise size is clearly shaped by age-specific ecological constraints; interestingly, it is likely the carapace that conducts the strategy, rather than maturity per se. [ABSTRACT FROM AUTHOR]

An organism's life history is closely interlinked with its allocation of energy between growth and reproduction at different life stages. Theoretical models have established that diminishing returns from reproductive investment promote strategies with simultaneous investment into growth and reproduction (indeterminate growth) over strategies with distinct phases of growth and reproduction (determinate growth). We extend this traditional, binary classification by showing that allocation-dependent fecundity and mortality rates allow for a large diversity of optimal allocation schedules. By analyzing a model of organisms that allocate energy between growth and reproduction, we find twelve types of optimal allocation schedules, differing qualitatively in how reproductive allocation increases with body mass. These twelve optimal allocation schedules include types with different combinations of continuous and discontinuous increase in reproduction allocation, in which phases of continuous increase can be decelerating or accelerating. We furthermore investigate how this variation influences growth curves and the expected maximum life span and body size. Our study thus reveals new links between eco-physiological constraints and life-history evolution and underscores how allocation-dependent fitness components may underlie biological diversity. [ABSTRACT FROM AUTHOR]

Abstract: The consequences of individual variation in life‐history traits have been well studied due to their importance in evolutionary ecology. However, a trait that has received little empirical attention is the rate of indeterminate growth. In long‐lived ectotherms, subtle variation in growth after maturity could have major effects over the animals’ lifetimes. These effects are difficult to measure due to the challenges involved in reliably estimating individual variation in the face of environmental stochasticity, and the need to account for trade‐offs among growth, reproduction and survival. However, modelling advances have made such analysis possible if long‐term high‐quality datasets are available. We used an integrated state‐space modelling framework to reveal relationships between indeterminate growth, reproduction and survival in a population of North American snapping turtles (Chelydra serpentina) using a 41‐year dataset for 298 adult females. A hierarchical version of the von Bertalanffy model fitted to data on carapace lengths showed substantial individual variation in growth trajectories, and hierarchical models fitted to clutch‐mass data and recapture histories showed that reproductive output and survival probability increased with size. Integration of these models revealed no detectable trade‐offs—i.e., individual growth parameters were not correlated with size‐specific survival or reproduction rates, and individual variation in reproductive output did not affect the size‐specific survival rate. Consequently, individual variation in growth parameters was estimated to result in >2‐fold variation in post‐maturity life expectancy and >4‐fold variation in expected lifetime reproductive output. These results illustrate that indeterminate growth can have major fitness consequences in long‐lived species. We suggest that the individual variation in growth rates reflects variation in environments experienced during development or later life. An understanding of this variation may be essential for predicting the population dynamics of long‐lived species under threat and identifying the most important environments to protect. A plain language summary is available for this article. [ABSTRACT FROM AUTHOR]

When resources are limited, organisms face allocation conflicts. Indeterminate growth creates a persistent conflict with reproduction, as growth may enhance future reproduction, but diverts resources from current reproduction. Little is known about allocation trade-offs in mammals with indeterminate growth. We studied growth and reproduction in adult female eastern grey kangaroos ( Macropus giganteus), an iteroparous mammal with indeterminate growth. Allocation trajectories varied with age and size: for 4-year-old females, fecundity increased from 30 to 82% from shortest to average-sized individuals. Older females had high fecundity regardless of size. The smallest females grew 30% more annually than average-sized females, but females that reached average size at an older age had lower growth rates. Environmental conditions affected allocation to size and reproduction. Rainy springs increased fecundity from 61 to 84% for females that had previously reproduced, but rainy winters reduced leg growth. Females in better relative condition grew 40% more than average, whereas most young of females below average relative condition failed to survive to 10 months of age. These results highlight an age-specific trade-off between growth and reproduction. Tall young females benefit from a smaller trade-off between somatic growth and early fecundity than shorter females of the same age, but older females appear to favor reproduction over growth regardless of size. Our study highlights how individual heterogeneity determines trade-offs between life-history components. We speculate that cohort effects affect age-specific reproductive success in this long-lived mammal. [ABSTRACT FROM AUTHOR]

In 2014, two forms of common bean (Phaseolus vulgaris L.), one wild and the other domesticated, both of undetermined growth habit type IV, climber, were cultivated in the greenhouse. The culture was performed in hydroponics allowing the maximum expression of its genetic potential. The wild and domesticated form of P. vulgaris is an important reservoir of genes for plant breeding. The objective was to make a mutual comparison of phenological, morphological characters and yield components, as well as some physiological variables such as leaf area duration, net assimilation rate, pod filling index and harvest index. The wild form has a longer cultivation cycle than the domesticated one and a greater number of pods from the stage of filling the pod to the maturity of harvest and in the latter a greater number of seeds per plant, although the seeds of a smaller size and individual weight; likewise, the percentage of germination was similar in both forms without the need to scarify the seed. In the wild form, the total production of dry matter per plant and the duration of the leaf area are greater, this last characteristic due to the fact that its foliage remains functional longer compared to the domesticated one. The net assimilation rate is higher in the domesticated, which indicates its precocity. The traditional and modified harvest index (including and excluding the root in both cases) is higher in the domesticated form due to selection under domestication. [ABSTRACT FROM AUTHOR]