Maturation Schedules Research Articles

A Protracted and Dynamic Maturation Schedule UnderliesArabidopsisLeaf Development

Leaf development has been monitored chiefly by following anatomical markers. Analysis of transcriptome dynamics during leaf maturation revealed multiple expression patterns that rise or fall with age or that display age-specific peaks. These were used to formulate a digital differentiation index (DDI) based on a set of selected markers with informative expression during leaf ontogeny. The leaf-based DDI reliably predicted the developmental state of leaf samples from diverse sources and was independent of mitotic cell division transcripts or propensity of specific cell types. When calibrated by informative root markers, the same algorithm accurately diagnosed dissected root samples. We used the DDI to characterize plants with reduced activities of multiple CINCINNATA (CIN)-TCP (TEOSINTE BRANCHED1, CYCLOIDEA, PCF) growth regulators. These plants had giant curled leaves made up of small cells with abnormal shape, low DDI scores, and low expression of mitosis markers, depicting the primary role of CIN-TCPs as promoters of differentiation. Delayed activity of several CIN-TCPs resulted in abnormally large but flat leaves with regular cells. The application of DDI has therefore portrayed the CIN-TCPs as heterochronic regulators that permit the development of a flexible and robust leaf form through an ordered and protracted maturation schedule.

Fisheries-induced evolution of maturation schedule in exploited stocks: Empirical and theoretical evidence, expected demographic implications and potential mitigation measures

Fisheries-induced evolution of maturation schedule in exploited stocks: Empirical and theoretical evidence, expected demographic implications and potential mitigation measures

Biphasic growth in fish II: Empirical assessment

In [Quince, et al., 2008. Biphasic growth in fish I: Theoretical foundations. J. Theor. Biol., doi: 10.1016/j.jtbi.2008.05.029], we developed a set of biphasic somatic growth models, where maturation is accompanied by a deceleration of growth due to allocation of energy to reproduction. Here, we use growth data from both hatchery-raised and wild populations of a large freshwater fish (lake trout, Salvelinus namaycush) to test these models. We show that a generic biphasic model provides a better fit to these data than the von Bertalanffy model. We show that the observed deceleration of somatic growth in females varies directly with gonad weight at spawning, with observed egg volumes roughly 50% of the egg volumes predicted under the unrealistic assumption of perfectly efficient energy transfer from somatic lipids to egg lipids. We develop a Bayesian procedure to jointly fit a biphasic model to observed growth and maturity data. We show that two variants of the generic biphasic model, both of which assume that annual allocation to reproduction is adjusted to maximise lifetime reproductive output, provide complementary fits to wild population data: maturation time and early adult growth are best described by a model with no constraints on annual reproductive investment, while the growth of older fish is best described by a model that is constrained so that the ratio of gonad size to somatic weight ( g) is fixed. This behaviour is consistent with the additional observation that g increases with size and age among younger, smaller breeding females but reaches a plateau among older, larger females. We then fit both of these optimal models to growth and maturation data from nineteen wild populations to generate population-specific estimates of ‘adapted mortality’ rate: the adult mortality consistent with observed growth and maturation schedules, given that both schedules are adapted to maximise lifetime reproductive output. We show that these estimates are strongly correlated with independent estimates of the adult mortality experienced by these populations.

Evolution of growth in Gulf of St Lawrence cod?

Fishing is often size selective such that the likelihood of capture increases with body size. It has therefore been postulated that fishing could favour evolution of slower growth because smaller size would reduce exposure to fishing gear (e.g. [Ricker 1981][1]). A recent study by Swain et al . ([

Predicting the event and time horizon of bankruptcy using financial ratios and the maturity schedule of long-term debt

We study the problem of simultaneous and coherent assessment the probability of a firm’s bankruptcy at various time horizons in future. In contrast with usual (one-period) formulations of the problem, such multi-period formulation better matches the nature of bankruptcy process (bankruptcy occurs in time) and allows an easier and more natural incorporation of bankruptcy (default) prognoses in valuation of risky debt and equity, optimization of corporate capital structure etc. The study uses a new mathematical apparatus—multi-alternative decision rules of statistical decision theory. We investigate a new type of predictive variables that can be extracted from the maturity schedule of a firm’s long-term debt. The study develops Bayesian-type forecasting rules that use both maturity schedule factors and traditional financial ratios. These rules noticeably enhance bankruptcy prediction (compared with the familiar one-period Z-score rules of Altman) for bankruptcy within the first 1, 2 or 3 years. Predictive factors derived from schedule information enhance bankruptcy prediction at distant time horizons.

Seasonal steroids variations and maturity stages in the female chub, Leuciscus cephalus L. (Pisces, Cyprinidae)

Biometric evaluation, ovary histomorphometry, plasma 17β‐estradiol (E2) and androgens (A) concentrations were investigated through the gonadal maturation and spawning of the wild chub, Leuciscus cephalus. A lower concentration of plasma E2 was recorded from January (oogonia) to March (previtellogenic oocytes), while estradiol concentrations increased in April, when the ovary mostly contained vitellogenic oocytes. In July, when it was prevalently composed of post‐ovulatory follicles, there was a decline in E2 plasma concentrations. Low concentrations of this steroid remained in the plasma until January, while high concentrations of androgens reached a peak in February and April preceding and following E2. The observed seasonal changes in plasma steroids, reflecting the pattern of follicles size development, were to a large extent consistent with observations made in other cyprinids. Since they define the reproductive cycle of the European female chub, they will be useful in the construction of a maturity schedule for wild populations.

Population specific smolt development, migration and maturity schedules in Atlantic salmon in a natural river environment

Identifying differences in quantitative life history traits between cultured and native or non-native wild populations is important in assessing the impact of accidental and deliberate introductions of hatchery-reared fish into the wild. As the ability to exploit the marine environment is the defining life history characteristic of anadromous salmonids, knowledge of variation in smoltification characteristics among populations is crucial in determining how these introductions affect fitness in recipient populations. Data are presented here describing the timing and extent of the autumn migration; the propensity for male parr maturation; the timing of the spring migration; and the size of autumn and spring migrants from Atlantic salmon (Salmo salar) populations from various genetic backgrounds. These experiments were carried out under common garden conditions over a decade in the Srahrevagh River in the west of Ireland. Population specific genetically determined differences in quantitative life history traits associated with smoltification were apparent. These differences may reflect smolt quality and therefore impact on marine survival and ultimately lifetime fitness. Both hatchery domestication and geography (different selective environments) were found to be important factors determining smolt phenotypes, although it was difficult to measure the relative contribution of each. These results indicate that farm, native hatchery, non-native wild salmon (even from a neighbouring catchment) and their hybrids with native wild fish, are likely to produce less well adapted and thus poorer quality smolts than native wild populations and, where wild populations are extant, such stocks should not be used for enhancement purposes.

Condition and Feeding of Greenland Halibut (Reinhardtius hippoglossoides) in the North Atlantic with Emphasis on the Flemish Cap

The Relative Condition Factor of Greenland halibut (Reinhardtius hippoglossoides) was analysed for seasonal, annual and geographical variability. Sampling covered commercial fishing and scientific surveys in three areas of the North Atlantic (NAFO Divisions 3M and 3LNO, and ICES Division IIb), comprising a total of 64 984 individuals from 1992 to 2003. Several data sets were established in order to carry out the comparisons: individuals as a whole; by sex females and males separately; and by areas each area independently. Condition showed significant differences with regard to the area, season, size range and sex, but it was not always significant among interactions of these factors. Individuals from the Northeast Atlantic had better condition, while those in the Northwest Atlantic suffered a notable fall in condition throughout the studied period, mainly in Flemish Cap. Condition was lightly superior in females, regarding size. A clear increment in the feeding intensity appeared when the condition diminished. When the total weight is used to calculate the condition, more remarkable differences could be expected because this index is sensitive to the gonad weight; in this respect, adult females showed more marked differences. Moreover, the complex maturity schedule and variable maturity at size would contribute to find misleading differences. Feeding habits of Greenland halibut were studied in the same areas based on a sample of 19 001 fish. Feeding intensity was the higher on the Flemish Cap, where the main preys were Pandalus borealis, Sebastes spp. and Serrivomer beani. P. borealis predation increased in the late 1990s. Diet was piscivorous in Div. 3LNO and Div. IIb as well, mainly based on Mallotus villosus and Micromesistius poutassou, respectively. Cannibalism and offal consumption was remarkable in Svalbard (ICES Div. IIb). Fish predation increased when predator size increased. Molluscs took an important place in the diet of intermediate sizes in Div. 3LNO and IIb. Similar diet pattern for both sexes was observed.

Probabilistic maturation reaction norms: their history, strengths, and limitations

Probabilistic maturation reaction norms (PMRNs) are emerging as a flexible and general tool for characterizing phenotypic plasticity in maturation schedules. Describing an organism's probability of maturing as a function of its age and size, PMRNs offer several beneficial features: (1) PMRNs overcome systematic biases that previously marred the estimation of deterministic matu- ration reaction norms for populations with probabilistic growth and maturation; (2) PMRNs remove the effects of varying mortality rates and average juvenile somatic growth rates from descriptions of maturation schedules; (3) PMRNs are defined at the level of individuals and can thus be treated as phenotypes when applying methods of quantitative genetics; (4) PMRNs serve as indispensable ingredients in process-based dynamical models of a population's age and size structure; and (5) PMRNs are readily extended to include effects on maturation of individual or environmental factors other than age and size. Owing to this combination of features, PMRNs allow many effects of phenotypic plasticity to be stripped away from the description of maturation schedules, so that residual trends are suggestive of genetic adaptation in maturation schedules. Here we review the historical developments that led to the introduction of PMRNs and address frequently asked ques- tions about their interpretation, utility, and application.

Why age and size at maturity have changed in Pacific salmon

Over the last few decades, the size at which Pacific salmon Oncorhynchus spp. attains maturity has decreased in many populations, whereas the age at maturity has increased. Both fish- eries-induced evolution and environmentally-induced phenotypic plasticity could contribute to the changing age and size at maturity of Pacific salmon. We evaluated the potential for genetic changes in the maturation schedule of Japanese chum salmon using the probabilistic maturation reaction norm (PMRN) method. We found that the recent decrease in size at maturity, and increase in age at maturity, of Japanese chum salmon can be largely attributed to a phenotypic response to a reduced growth rate, but that fisheries-induced evolution should not be ruled out. Recent claims concerning fisheries-induced evolution of the maturation schedule are based on the decline in the age-specific body size at which the probability of maturing is 50%, a feature of PMRNs. However, the PMRN could change with changing environmental conditions. Therefore, a genetic change cannot be diagnosed only by the PMRN method.

Predicting the Event and Time Horizon of Bankruptcy Using Financial Ratios and the Maturity Schedule of Long-Term Debt

This study investigates the multi-period prediction of firm bankruptcy as a multi-alternative problem of Statistical Decision Theory. This approach enables a simultaneous assessment to be made of the prediction of bankruptcy and the time horizon at which the bankruptcy could occur. To illustrate the approach, using U.S. bankruptcy data, a comparative statistical analysis of various financial variables is undertaken to identify four relatively independent financial ratios that have the potential for multi-period bankruptcy forecasting. These ratios characterize the quantity and quality of debt, as well as the firm's ability to repay the debt. The study also investigates a new type of predictive information - the maturity schedule of a firm's long-term debt. Bayesian-type forecasting rules are developed that jointly use the financial ratios and maturity schedule factors. The rules noticeably enhance bankruptcy prediction compared with the familiar one-period (two-alternative) Z-score rules of Altman (1968) for bankruptcy within the first one, two or three years. Predictive factors derived from schedule information additionally enhance bankruptcy prediction at distant time horizons.

Growth and Maturity of Hatchery and Wild Lean Lake Trout during Population Recovery in Michigan Waters of Lake Superior

AbstractThe recovery of populations of wild lake troutSalvelinus namaycushin Lake Superior was the first success among Great Lakes—wide rehabilitation efforts for this species. Knowledge of changes in major demographic factors (e.g., growth and maturity schedules) is very important for enhancing our understanding of stock status during the recovery process, particularly for a fish population with a relatively long life span, such as lake trout in Lake Superior. We separated the recovery time line into three periods—hatchery dominant (1970–1979), transitional (1980–1985), and wild dominant (1986–2003)—and compared growth and sexual maturity (1) between hatchery‐ and wild‐origin lake trout within each period and (2) among the three periods for a given origin. In all three periods, the lengths at old ages (age >6) were similar between wild and hatchery lake trout, but wild fish had smaller lengths at ages 4–6 and at maturity than did hatchery fish. Consequently, wild lake trout had a lower wounding rate by sea lampreyPetromyzon marinusand higher survival than did hatchery lake trout at a given maturity level. Across the three periods, both wild and hatchery lake trout showed significant declines in mean length at old ages and length at 50% maturity, while declines in length at young ages were not significant. Those temporal declines corresponded with the increase in wild lake trout abundance to historic high levels and the lower abundance of major prey fishes. Our estimates of age at 50% maturity also increased over time, but excessive variance in age determinations precluded statistical significance. The observed dynamics of lake trout growth and maturation in the context of population recovery and food web changes are valuable for studying the population dynamics of harvested fish populations.

DOES SIZE MATTER MOST? THE EFFECT OF GROWTH HISTORY ON PROBABILISTIC REACTION NORM FOR SALMON MATURATION

Body size is widely believed to affect the occurrence of sexual maturation. Recent studies have used changes in the age-specific body size at which the probability of maturing is 50%, a feature of probabilistic reaction norms, to quantify purported evolution of life histories. However, body size results from a combination of growth rates during successive developmental stages. Therefore, to understand the evolution of the maturation schedule, it is necessary to comprehend the relationships among body size, growth history, and maturation schedule. We examined the relationships among body size, previous growth history, and maturation probability in chum salmon (Oncorhynchus keta). In this study, previous growth history was estimated from yearly specific growth increments that provide information describing body size. Previous growth history was found to be more closely linked to maturation probability than body size. The most recent growth condition was the most important factor affecting whether a fish matured during the subsequent breeding season. Because individuals of similar body size and same age can have different growth histories, the relationship between body size and maturation probability could be plastically modified by growth history. This may violate an assumption required to infer evolution, namely that size-related maturation trends in probabilistic reaction norms are immune to growth history.

Automated egg counting and sizing from scanned images: Rapid sample processing and large data volumes for fecundity estimates

The production of eggs in a fish population is a fundamental parameter in fisheries management and ecology. Management decisions are based largely on the abundance and composition of the spawning stock; hence it is essential to estimate the contribution of viable eggs by females of various ages, which may depend on the size and maturation schedules in females of younger ages, and the size and reproductive senescence of older ones. The level of recruitment may also be influenced by the size and quality of eggs. Egg quality can be characterised in a number of ways; however, the most useful methods are those that are efficient and widely available. Estimating potential fecundity and egg size in fish and invertebrate populations has been hindered by the processing time, toxicity, and resources required by traditional methods. We have developed an imaging-based technique that counts and measures oocytes from a gravimetric gonadal sub-sample in relatively little time and at low cost. Sub-samples were preserved in a non-toxic formulation of Gilson's solution, which offers an alternative to other preservatives commonly used in fecundity studies. The technique uses high-resolution optical scans of plated oocytes, imaging software, and user-defined object classifications to separate oocyte from ancillary material likely to be present in a processed sample. Estimates of misclassification are as low as 1% (false-negatives) in automated counts.

Assessing changes in age and size at maturation in collapsing populations of Atlantic cod (Gadus morhua)

By estimating probabilistic reaction norms for age and size at maturation, we show that maturation schedules of Atlantic cod (Gadus morhua) off Labrador and Newfoundland shifted toward earlier ages and smaller sizes during the late 1980s and early 1990s, when these populations underwent a severe collapse in biomass and subsequently were closed for directed commercial fishing. We also demonstrate that this trend towards maturation at younger ages and smaller sizes is halted and even shows signs of reversal during the closure of the fisheries. In addition, our analysis reveals that males tend to mature earlier and at a smaller size than females and that maturation age and size decrease with increasing latitude. Importantly, the maturation reaction norms presented here are robust to variation in survival and growth (through phenotypic plasticity) and are thus strongly indicative of rapid evolutionary changes in cod maturation as well as of spatial and sex-specific genetic variation. We therefore suggest that maturation reaction norms can provide helpful reference points for managing harvested populations with evolving life histories.

Embryological study of the glottic site and clinical implications

The development of the glottic site, in particular of its ventral area, was studied to better understand the spreading pathways of T1, T2 cancer. Serial sections of larynges from human embryos, fetuses and adults were observed. A dorsal, a ventral and an intermediate compartment were found on the basis of their maturation schedule. A commissure muscle which develops in the anterior one third of the glottic site and wraps the connection system of vocal ligaments was recognized. The inferior paraglottic space, the compartment structures and the localization of superficial and deep blood vessels and of glands in the ventral compartment and the components of Broyles ligament were studied during ontogenesis. The compartments identified here have clinical and oncological relevance. Their detailed knowledge offers a prerequisite for planning and performing compartment conservative surgery in T1, T2 cancer, based on their spreading pathways.

The relationship between fish condition and the probability of being mature in American plaice (Hippoglossoides platessoides)

Abstract Fish condition can be related to a population's reproductive potential in a variety of ways. The relationship between condition and the probability of being mature (adult) was examined in three populations of American plaice (Hippoglossoides platessoides). The effect of condition was tested after first removing the known effects of age and length. Neither relative liver condition nor relative body condition significantly affected the probability of male American plaice being mature, but there was a significant positive effect of both condition indices on the probability of being a mature female. However, the additional variation explained by female condition was small when compared with the combined effect of age and length. Condition is related to the age and size at which fish attain adulthood. Variation in fish condition will have a direct impact on the spawning stock biomass of a population through differences in the maturation schedule of cohorts with differing condition.

Testicular Size, Mating System, and Maturation Schedules in Wild Anubis and Hamadryas Baboons

We report body mass and testicular size in 258 anubis (Papio anubis or P. hamadryas anubis) and 59 hamadryas (P. hamadryas or P. h. hamadryas) baboons, live-trapped in Ethiopia. As predicted by theories of sexual selection by sperm competition, among hamadryas baboons, which are monandrous, fully adult males have absolutely and relatively smaller testes than those of comparable males among anubis baboons, which are polyandrous. Male hamadryas are also ca. 10% smaller in bodily mass as adults. The intertaxonal difference in adults is due entirely to the fact that in male anubis baboons, testicular and bodily mass continue to grow up to full adulthood–the age at which most males emigrate from their natal troop and initiate a confrontational breeding strategy among unrelated animals. By contrast, male hamadryas baboons, which are usually philopatric, attain adult body mass and testicular size as subadults. In both species, juveniles experience rapid testicular growth peaking in rate at ca. 12kg body mass, but testicular descent and growth starts earlier in hamadryas than in anubis baboons. Juvenile hamadryas baboons have relatively larger testes than their anubis equivalents, perhaps because male philopatry allows the mating strategy of male hamadryas baboons to be initiated during juvenile life and therefore permits some sperm competition between juveniles and adults.

Interpreting Maturation Data for American Shad in the Presence of Fishing Mortality: A Look at Historical Data from the York River, Virginia

To enable better monitoring, forecasting, and establishment of restoration targets, we undertook a study of maturation by American shad Alosa sapidissima in the York River, Virginia. Throughout the study, the need for historical information about the status of the stock and how it relates to the current depressed state was evident. We identified an early study (covering the years 1957–1959) that might allow reconstruction of maturation schedules for historical time periods and enable comparison with contemporary maturation schedules. When a commercial fishery is operating, mature survival can differ from immature survival for a given age because the immature fish remain offshore and do not experience the fishing mortality imposed on adults in the spawning river. Thus, a maturity model that can account for the relationship between mature and immature survival is required and was developed here. A process for reconstructing data matrices from published data summaries was developed that led to the discovery of errors in the historical source. For the year in which the errors could be corrected (1959), maturation parameters were estimated using the method developed here for various levels of the ratio of mature to immature survival (including that inferred from the exploitation rate reported in the historical study). Additionally, microfiche data were located that provided the information necessary to estimate maturation parameters for 1955 and 1956. The estimated maturation schedule for 1959 was earlier than the present estimated schedule, while those for 1955 and 1956 were later. Because a greater range of ages was sampled in 1955 and 1956 and the maturity estimates for those years were in agreement with each other and in line with ecological expectations, we accept those estimates over the ones obtained from the 1959 data and conclude that at present the maturation of American shad occurs earlier than it did during the historical period.

Effect of temperature on growth and maturity of the king crabs <i>Paralithodes brevipes</i> and <i>P. camtschaticus</i> in the laboratory

The effect of temperature on growth and maturity was studied for the king crabs Paralithodes brevipes (Pb) and P. camtschaticus (Pc) in the laboratory. Molting and growth were examined individually in cultured first instar juveniles of Pb and Pc and in 2 and 3 y-old Pb collected in the wild (wild Pb). Crabs were fed mussels daily. Two temperature regimes were used, ambient (AT: -1 to 17°C) and controlled (CT: +11 to 13°C). After 4 y, Pb had reached instars 17-19 (71mm carapace length [CL], 330g) at AT, and instars 22-23 (95mm CL, 770g) at CT. Pc had reached instars 18-19 (82mm CL, 380g) at AT, and instars 20-21 (109mm CL, 1050g) at CT. Female 4 y-old Pc cultured at CT spawned after mating with 4 y males. Female Pb cultured at CT were not mature at 4 y although 4 y males did mate with 6 y females (wild Pb cultured from 2 to 6 y at AT). Thus, the growth pattern was similar between Pb and Pc, but CT had different effects on the maturation schedules of the females of the two species. At AT, no crabs were mature at 4 y.