scholarly journals Zinc concentrations in teeth of female walruses reflect the onset of reproductive maturity

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Casey T Clark ◽  
Lara Horstmann ◽  
Nicole Misarti
Keyword(s):  
Life History ◽  
Carrying Capacity ◽  
Change Point ◽  
Linear Increase ◽  
Research Management ◽  
Pacific Walrus ◽  
Reproductive Maturity ◽  
Demographic Models ◽  
Novel Approach ◽  
Incremental Growth

Abstract Age at maturity is an important parameter in many demographic models and, for some species, can be difficult to obtain using traditional methods. Incremental growth structures act as biological archives, recording information throughout an organism’s life and possibly allowing for the reconstruction of life history events. Concentrations of zinc (Zn) in animal tissues are known to be linked to life history, physiology and reproduction and may be retained in incremental growth structures. This study reconstructed lifetime Zn concentrations in teeth (n = 93) of female Pacific walruses (Odobenus rosmarus divergens) collected from 1932–2016. Zn displayed a characteristic pattern of accumulation, with a change point marking the beginning of a lifelong, linear increase in Zn concentrations. We hypothesized that this change point marks the onset of reproductive maturity. The age at which the change point occurred (agecp) was estimated by counting tooth cementum growth layers. These estimates closely matched literature values of timing of first ovulation in female walruses. Total number of ovulations (estimated from ovary corpora counts from paired tooth/ovary specimens) was closely related to reproductive lifespan (total lifespan – agecp; R2 = 0.70). Further, agecp tracked changes in Pacific walrus population size as a proportion of carrying capacity, decreasing when the population was depleted by commercial hunting and peaking when carrying capacity was exceeded. This novel approach will aid walrus management, and is likely applicable to other species, offering a potentially powerful tool for research, management and conservation of wildlife populations.

Twinning in Susceptible Mothers—An Exploratory Study of International Data by Payami's Models Suggests “Reproductive Maturity” as a Risk Factor

1991 ◽  
Vol 40 (3-4) ◽  
pp. 269-289 ◽  
Author(s):  
P. Philippe
Keyword(s):  
Maternal Age ◽  
Comparison Group ◽  
Linear Increase ◽  
Reproductive Maturity ◽  
Secondary Exposure ◽  
Twin Birth ◽  
Age Dependent ◽  
Common Etiology ◽  
International Data ◽  
The Common

AbstractAn attempt has been made to apply Payami's models to maternal age-specific twin birth prevalences in several countries. The models disclose the heterogeneity of a cohort and spell out the risks to susceptible members (who will actually get the disease) according to age (or time). Payami's method specifies that the typical cohort of susceptibles is ascribed to two exposures: a potent and generalised exposure and a very low or no risk secondary exposure. The models have been adjusted to international data from current as well as old populations, of Occidental and Japanese origin. Results show that cohorts of twin-prone mothers aged 25 to 45 are homogeneous. A single dominant etiology is suggested which applies to both MZ and DZ twins. Heterogeneity, from 10% to 25%, is present in all countries whenever the 20-24 age group is involved. A separate study of illegitimate twin births from Denmark reduces the heterogeneity and shows that MZ illegitimate twin births are due to a secondary exposure responsible for a distinct twinning etiology. The age-specific risks of a MZ illegitimate twin birth are much higher than those of any comparison group, and are constant until age 35 years. This suggests a single-hit exposure akin to a neuroendocrine stimulus which short-cuts the usual age-dependent etiologic pathway. MZ and DZ twins both experience the same maternal age specific risks, an observation which underscores the common etiology of both types of twins. Risks increase with age from age 20 to 45 years. The pattern according to age varies among countries and time periods. Occidental populations have a pattern varying from an exponential to a more linear increase in old and recent populations, respectively. Only present-day Japan displays a logarithmic-like growth curve. The concept of “reproductive maturity” is introduced, and related to the secular trend of the DZ twin birth risk and to its variation across countries. Two new conclusions are drawn: a) The higher the rate of reproductive maturity, the less the DZ twin birth risk and, b) Reproductive maturity determines the maternal age-specific gonadotropin levels.

scholarly journals Coalescence times, life history traits and conservation concerns: an example from four coastal shark species from the Indo-Pacific

2021 ◽  
Author(s):  
Pierre Lesturgie ◽  
Serge Planes ◽  
Stefano Mona
Keyword(s):  
Population Structure ◽  
Life History ◽  
Life History Traits ◽  
New Caledonia ◽  
Demographic History ◽  
Conservation Strategies ◽  
Shark Species ◽  
Effective Population ◽  
Demographic Models ◽  
Mobile Species

Dispersal abilities play a crucial role in shaping the extent of population genetic structure, with more mobile species being panmictic over large geographic ranges and less mobile ones organized in meta-populations exchanging migrants to different degrees. In turn, population structure directly influences the coalescence pattern of the sampled lineages, but the consequences on the estimated variation of the effective population size (Ne) over time obtained by means of unstructured demographic models remain poorly understood. However, this knowledge is crucial for biologically interpreting the observed Ne trajectory and further devising conservation strategies in endangered species. Here we investigated the demographic history of four shark species (Carharhinus melanopterus, Carharhinus limbatus, Carharhinus amblyrhynchos, Galeocerdo cuvier) with different degrees of endangered status and life history traits related to dispersal distributed in the Indo-Pacific and sampled off New Caledonia. We compared several evolutionary scenarios representing both structured (meta-population) and unstructured models and then inferred the Ne variation through time. By performing extensive coalescent simulations, we provided a general framework relating the underlying population structure and the observed Ne dynamics. On this basis, we concluded that the recent decline observed in three out of the four considered species when assuming unstructured demographic models can be explained by the presence of population structure. Furthermore, we also demonstrated the limits of the inferences based on the sole site frequency spectrum and warn that statistics based on linkage disequilibrium will be needed to exclude recent demographic events affecting meta-populations.

scholarly journals Influence of Lab Adapted Natural Diet and Microbiota on Life History and Metabolic Phenotype of Drosophila melanogaster

2020 ◽  
Vol 8 (12) ◽  
pp. 1972
Author(s):  
Andrei Bombin ◽  
Owen Cunneely ◽  
Kira Eickman ◽  
Sergei Bombin ◽  
Abigail Ruesy ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Life History ◽  
Development Rate ◽  
Metabolic Phenotype ◽  
Natural Diet ◽  
Theory Of Evolution ◽  
Nutritional Conditions ◽  
Novel Approach ◽  
Survival And Development ◽  
Symbiotic Microbiota

Symbiotic microbiota can help its host to overcome nutritional challenges, which is consistent with a holobiont theory of evolution. Our project investigated the effects produced by the microbiota community, acquired from the environment and horizontal transfer, on metabolic traits related to obesity. The study applied a novel approach of raising Drosophila melanogaster, from ten wild-derived genetic lines on naturally fermented peaches, preserving genuine microbial conditions. Larvae raised on the natural and standard lab diets were significantly different in every tested phenotype. Frozen peach food provided nutritional conditions similar to the natural ones and preserved key microbial taxa necessary for survival and development. On the peach diet, the presence of parental microbiota increased the weight and development rate. Larvae raised on each tested diet formed microbial communities distinct from each other. The effect that individual microbial taxa produced on the host varied significantly with changing environmental and genetic conditions, occasionally to the degree of opposite correlations.

scholarly journals Switch between Life History Strategies Due to Changes in Glycolytic Enzyme Gene Dosage inSaccharomyces cerevisiae

2010 ◽  
Vol 77 (2) ◽  
pp. 452-459 ◽  
Author(s):  
Shaoxiao Wang ◽  
Aymé Spor ◽  
Thibault Nidelet ◽  
Pierre Montalent ◽  
Christine Dillmann ◽  
...  
Keyword(s):  
Life History ◽  
Cell Size ◽  
Carrying Capacity ◽  
Life History Traits ◽  
Gene Dosage ◽  
Single Gene ◽  
Glycolytic Enzyme ◽  
Life History Strategies ◽  
Glucose Consumption Rate ◽  
Glycolytic Gene

ABSTRACTAdaptation is the process whereby a population or species becomes better fitted to its habitat through modifications of various life history traits which can be positively or negatively correlated. The molecular factors underlying these covariations remain to be elucidated. UsingSaccharomyces cerevisiaeas a model system, we have investigated the effects on life history traits of varying the dosage of genes involved in the transformation of resources into energy. Changing gene dosage for each of three glycolytic enzyme genes (hexokinase 2, phosphoglucose isomerase, and fructose-1,6-bisphosphate aldolase) resulted in variation in enzyme activities, glucose consumption rate, and life history traits (growth rate, carrying capacity, and cell size). However, the range of effects depended on which enzyme was expressed differently. Most interestingly, these changes revealed a genetic trade-off between carrying capacity and cell size, supporting the discovery of two extreme life history strategies already described in yeast populations: the “ants,” which have lower glycolytic gene dosage, take up glucose slowly, and have a small cell size but reach a high carrying capacity, and the “grasshoppers,” which have higher glycolytic gene dosage, consume glucose more rapidly, and allocate it to a larger cell size but reach a lower carrying capacity. These results demonstrate antagonist pleiotropy for glycolytic genes and show that altered dosage of a single gene drives a switch between two life history strategies in yeast.

scholarly journals Optimal immune specificity at the intersection of host life history and parasite epidemiology

2021 ◽  
Vol 17 (12) ◽  
pp. e1009714
Author(s):  
Alexander E. Downie ◽  
Andreas Mayer ◽  
C. Jessica E. Metcalf ◽  
Andrea L. Graham
Keyword(s):  
Life History ◽  
Life History Traits ◽  
Reproductive Maturity ◽  
Structured Population ◽  
Specificity And Sensitivity ◽  
Population Dynamics Model ◽  
Structured Population Dynamics ◽  
Host Life ◽  
The Relationship ◽  
Shed Light

Hosts diverge widely in how, and how well, they defend themselves against infection and immunopathology. Why are hosts so heterogeneous? Both epidemiology and life history are commonly hypothesized to influence host immune strategy, but the relationship between immune strategy and each factor has commonly been investigated in isolation. Here, we show that interactions between life history and epidemiology are crucial for determining optimal immune specificity and sensitivity. We propose a demographically-structured population dynamics model, in which we explore sensitivity and specificity of immune responses when epidemiological risks vary with age. We find that variation in life history traits associated with both reproduction and longevity alters optimal immune strategies–but the magnitude and sometimes even direction of these effects depends on how epidemiological risks vary across life. An especially compelling example that explains previously-puzzling empirical observations is that depending on whether infection risk declines or rises at reproductive maturity, later reproductive maturity can select for either greater or lower immune specificity, potentially illustrating why studies of lifespan and immune variation across taxa have been inconclusive. Thus, the sign of selection on the life history-immune specificity relationship can be reversed in different epidemiological contexts. Drawing on published life history data from a variety of chordate taxa, we generate testable predictions for this facet of the optimal immune strategy. Our results shed light on the causes of the heterogeneity found in immune defenses both within and among species and the ultimate variability of the relationship between life history and immune specificity.

scholarly journals A stepwise stochastic simulation approach to estimate life history parameters for data-poor fisheries

2016 ◽  
Vol 73 (12) ◽  
pp. 1874-1884 ◽  
Author(s):  
Marc O. Nadon ◽  
Jerald S. Ault
Keyword(s):  
Life History ◽  
Stock Assessment ◽  
Probability Distributions ◽  
Size Composition ◽  
History Data ◽  
Life History Parameters ◽  
Life History Data ◽  
Novel Approach ◽  
Cost Efficient ◽  
Species Specific

Coastal fisheries are typically characterized by species-rich catch compositions and limited management resources, which typically leads to notably data-poor situations for stock assessment. Some parsimonious stock assessment approaches rely on cost-efficient size composition data, but these also require estimates of life history parameters associated with natural mortality, growth, and maturity. These parameters are unavailable for most exploited stocks. Here, we present a novel approach that uses a local estimate of maximum length and statistical relationships between key life history parameters to build multivariate probability distributions that can be used to parameterize stock assessment models in the absence of species-specific life history data. We tested this approach on three fish species for which empirical length-at-age and maturity data were available (from Hawaii and Guam) and calculated probability distributions of spawning potential ratios (SPR) at different exploitation rates. The life history parameter and SPR probability distributions generated from our data-limited analytical approach compared well with those obtained from bootstrap analyses of the empirical life history data. This work provides a useful new tool that can greatly assist fishery stock assessment scientists and managers in data-poor situations, typical of most of the world’s fisheries.

scholarly journals Coalescent times, life history traits and conservation concerns: an example from four shark species from the Indo-Pacific

2021 ◽  
Author(s):  
Pierre Lesturgie ◽  
Serge Planes ◽  
Stefano Mona
Keyword(s):  
Population Structure ◽  
Life History ◽  
Life History Traits ◽  
New Caledonia ◽  
Demographic History ◽  
Conservation Strategies ◽  
Shark Species ◽  
Effective Population ◽  
Demographic Models ◽  
Mobile Species

Dispersal abilities play a crucial role in shaping the extent of population genetic structure, with more mobile species being panmictic over large geographic ranges and less mobile ones organized in meta-populations exchanging migrants to different degrees. In turn, population structure directly influences the coalescent pattern of the sampled lineages, but the consequences on the estimated variation of the effective population size (Ne) over time obtained by means of unstructured demographic models remain poorly understood. However, this knowledge is crucial for biologically interpreting the observed Ne trajectory and further devising conservation strategies in endangered species. Here we investigated the demographic history of four shark species (Carharhinus melanopterus, Carharhinus limbatus, Carharhinus amblyrhynchos, Galeocerdo cuvier) with different degrees of endangered status and life history traits related to dispersal distributed in the Indo-Pacific and sampled off New Caledonia. We compared several evolutionary scenarios representing both structured (meta-population) and unstructured models and then inferred the Ne variation through time. By performing extensive coalescent simulations, we provided a general framework relating the underlying population structure and the observed Ne dynamics. On this basis, we concluded that the recent decline observed in three out of the four considered species when assuming unstructured demographic models can be explained by the presence of population structure. Furthermore, we also demonstrated the limits of the inferences based on the sole site frequency spectrum and warn that statistics based on linkage disequilibrium will be needed to exclude recent demographic events affecting meta-populations.

scholarly journals Universality of evolutionary dynamics with arbitrary demography

2021 ◽  
Author(s):  
Andrea Mazzolini ◽  
Jacopo Grilli
Keyword(s):  
Life History ◽  
Population Size ◽  
Carrying Capacity ◽  
Life History Traits ◽  
Evolutionary Dynamics ◽  
Large Body ◽  
Chemostat Model ◽  
Scale Separation ◽  
Invasion Fitness ◽  
Effective Life

The assumption of constant population size is central in population genetics. It led to a large body of results, which have proven successful to understand evolutionary dynamics. Part of this success is due to their robustness to modeling choices. On the other hand, allele frequencies and population size are both determined by the interaction between a population and the environment. Including explicitly the demographic factors and life-history traits that determine the eco-evolutionary dynamics makes the analysis difficult and the results dependent on model details. Here, we develop a framework that encompasses a great variety of systems with arbitrary population dynamics and competition between species. By using techniques based on scale separation for stochastic processes, we are able to compute evolutionary properties, such as the invasion probability. Remarkably, these properties assume a universal form with respect to our framework, which depends on only three life-history traits related to the exponential fitness, the invasion fitness, and the carrying capacity of the alleles. In other words, different systems, such as Lotka-Volterra or a chemostat model, share the same evolutionary outcomes after the correct remapping of the parameters of the models into three effective life-history traits. An important and surprising consequence of our results is that the direction of selection can be inverted, with a population evolving to reach lower values of fitness. This can happen because the obtained frequency-dependent noise (affected by the three life-history traits) can generate an effective force that counterbalance classical selection.

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