Small-Sized Microplastics Negatively Affect Rotifers: Changes in the Key Life-History Traits and Rotifer–Phaeocystis Population Dynamics

2019 ◽  
Vol 53 (15) ◽  
pp. 9241-9251 ◽  
Author(s):  
Yunfei Sun ◽  
Wenjie Xu ◽  
Qiujin Gu ◽  
Yitong Chen ◽  
Qiming Zhou ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Life History ◽  
Life History Traits

Life history and environmental influences on population dynamics in sockeye salmon

2014 ◽  
Vol 71 (8) ◽  
pp. 1198-1208 ◽  
Author(s):  
Douglas C. Braun ◽  
John D. Reynolds
Keyword(s):  
Population Dynamics ◽  
Life History ◽  
Population Growth ◽  
Growth Rates ◽  
Environmental Conditions ◽  
Sockeye Salmon ◽  
Life History Traits ◽  
Relative Importance ◽  
Population Growth Rates ◽  
Habitat Variables

Understanding linkages among life history traits, the environment, and population dynamics is a central goal in ecology. We compared 15 populations of sockeye salmon (Oncorhynchus nerka) to test general hypotheses for the relative importance of life history traits and environmental conditions in explaining variation in population dynamics. We used life history traits and habitat variables as covariates in mixed-effect Ricker models to evaluate the support for correlates of maximum population growth rates, density dependence, and variability in dynamics among populations. We found dramatic differences in the dynamics of populations that spawn in a small geographical area. These differences among populations were related to variation in habitats but not life history traits. Populations that spawned in deep water had higher and less variable population growth rates, and populations inhabiting streams with larger gravels experienced stronger negative density dependence. These results demonstrate, in these populations, the relative importance of environmental conditions and life histories in explaining population dynamics, which is rarely possible for multiple populations of the same species. Furthermore, they suggest that local habitat variables are important for the assessment of population status, especially when multiple populations with different dynamics are managed as aggregates.

scholarly journals Revealing Evolutionarily Optimal Strategies in Self-Reproducing Systems via a New Computational Approach

2019 ◽  
Vol 81 (11) ◽  
pp. 4701-4725 ◽  
Author(s):  
Simran Kaur Sandhu ◽  
Andrew Morozov ◽  
Oleg Kuzenkov
Keyword(s):  
Population Dynamics ◽  
Life History ◽  
Water Column ◽  
Life History Traits ◽  
Initial Conditions ◽  
Vertical Motion ◽  
Optimal Strategies ◽  
Natural World ◽  
Computational Method ◽  
Behavioural Patterns

AbstractModelling the evolution of complex life history traits and behavioural patterns observed in the natural world is a challenging task. Here, we develop a novel computational method to obtain evolutionarily optimal life history traits/behavioural patterns in population models with a strong inheritance. The new method is based on the reconstruction of evolutionary fitness using underlying equations for population dynamics and it can be applied to self-reproducing systems (including complicated age-structured models), where fitness does not depend on initial conditions, however, it can be extended to some frequency-dependent cases. The technique provides us with a tool to efficiently explore both scalar-valued and function-valued traits with any required accuracy. Moreover, the method can be implemented even in the case where we ignore the underlying model equations and only have population dynamics time series. As a meaningful ecological case study, we explore optimal strategies of diel vertical migration (DVM) of herbivorous zooplankton in the vertical water column which is a widespread phenomenon in both oceans and lakes, generally considered to be the largest synchronised movement of biomass on Earth. We reveal optimal trajectories of daily vertical motion of zooplankton grazers in the water column depending on the presence of food and predators. Unlike previous studies, we explore both scenarios of DVM with static and dynamic predators. We find that the optimal pattern of DVM drastically changes in the presence of dynamic predation. Namely, with an increase in the amount of food available for zooplankton grazers, the amplitude of DVM progressively increases, whereas for static predators DVM would abruptly cease.

scholarly journals Going all the way: The implications of life history and phenotype on reproductive success of the common triplefin, Forsterygion lapillum

2021 ◽  
Author(s):  
◽  
Benjamin Moginie
Keyword(s):  
Population Dynamics ◽  
Life History ◽  
Reproductive Success ◽  
Parental Care ◽  
Growth Rates ◽  
Life Histories ◽  
Life History Traits ◽  
Evolutionary Ecology ◽  
Adult Males ◽  
The Common

<p>Identifying sources of variation in individual reproductive success is crucial to our understanding of population dynamics and evolutionary ecology. In many systems, the determinants of success are not well known. Where species have parental care, for example, determinants of success can be particularly challenging to partition between parents and offspring. In this thesis I investigate drivers and consequences of variable life histories, for a small reef fish that exhibits male parental care (the common triplefin Forsterygion lapillum). I examined the influence of individual life history, phenotype and behaviour on (1) the performance of recently settled juveniles, and (2) the reproductive success adult males.  I made field-based observations of adult males during the breeding season, measured their phenotypic traits (body size and condition) and used their otoliths to reconstruct life history characteristics (hatch dates and mean growth rates). My life history trait reconstructions suggested two alternate pathways to ’success’ for adult males. Successful males hatched earlier and therefore had a developmental ’head start’ over less successful males (i.e., males with eggs > male territory holders without eggs > floaters). Alternatively, males can apparently achieve success by growing faster: for males born in the same month, those with eggs grew faster than those with territories and no eggs, and both groups grew faster than floaters. These results suggest that accelerated growth rate may mediate the effects of a later hatch date, and that both hatch dates and growth rates influence the success of adult males, likely through proximate effects on individual phenotypes.  Identifying sources of variation in individual reproductive success is crucial to our understanding of population dynamics and evolutionary ecology. In many systems, the determinants of success are not well known. Where species have parental care, for example, determinants of success can be particularly challenging to partition between parents and offspring. Male parental care is common among fishes, where resources such as high quality territories and mates often may be limiting. In such systems, individual success of offspring may result from distinct life history pathways that are influenced by both parental effects (e.g., timing of reproduction) and by the offspring themselves (e.g., ’personalities’). These pathways, in turn, can induce phenotypic variation and affect success later in life. The drivers and consequences of variable life histories are not well understood in the context of reproductive success.  In this thesis I investigate drivers and consequences of variable life histories, for a small reef fish that exhibits male parental care (the common triplefin Forsterygion lapillum). I examined the influence of individual life history, phenotype and behaviour on (1) the performance of recently settled juveniles, and (2) the reproductive success adult males. I made field-based observations of adult males during the breeding season, measured their phenotypic traits (body size and condition) and used their otoliths to reconstruct life history characteristics (hatch dates and mean growth rates). Some males showed no evidence of territorial defence and were defined as ’floaters’; others defended territories, and a subset of these also had nests with eggs present. Adult male body size was significantly higher for males that defended breeding territories, and body condition was significantly higher for the males that had eggs (i.e., had successfully courted females). My otolith-based reconstructions of life history traits suggested two alternate pathways to ’success’ for adult males. Successful males hatched earlier and therefore had a developmental ’head start’ over less successful males (i.e., males with eggs > male territory holders without eggs > floaters). Alternatively, males can apparently achieve success by growing faster: for males born in the same month, those with eggs grew faster than those with territories and no eggs, and both groups grew faster than floaters. These results suggest that accelerated growth rate may mediate the effects of a later hatch date, and that both hatch dates and growth rates influence the success of adult males, likely through proximate effects on individual phenotypes.  I evaluated the effects of variable life history in a complimentary lab-based study. Specifically, I manipulated the developmental environments (feeding regime and temperature) for young fish and evaluated the direct effects on life history traits and phenotypes. Then, I conducted an assay to quantify the indirect effects of developmental environment, life history traits, and phenotypes on aggression and performance of young fish. These developmental environments did not have a clear, overall effect on juvenile phenotype or performance (i.e. behavioural aggression and the ability to dominate a resource). Instead, individuals (irrespective of developmental environment) that grew faster and/or longer pelagic larval durations had increased odds of dominating a limited resource. I attributed the non-significant direct effect of developmental environment to within-treatment mortality and variation among individuals in terms of their realised access to food (i.e., dominance hierarchies were apparent in rearing chambers, suggesting a non-uniform access to food). Fish that were more likely to dominate a resource were also more aggressive (i.e., more likely to engage in chasing behaviours). Fish that were larger and more aggressive established territories that were deemed to be of higher ’quality’ (inferred from percent cover of cobble resources). Overall, this study suggests a complex interplay between social systems, phenotype and life history. Developmental environments may influence phenotypes, although behavioural differences among individuals may moderate that effect, contributing to additional variation in phenotypes and life history traits which, in turn, shape the success of individuals.  Collectively, my thesis emphasises the consequences of life history variability on success at multiple life stages. These results may be relevant to other species that exhibit male parental care or undergo intense competition for space during early life stages. In addition, my results highlight interactions between life history, phenotype and behaviour that can have important implications for population dynamics and evolutionary ecology.</p>

scholarly journals Integrative developmental ecology: a review of density-dependent effects on life-history traits and host-microbe interactions in non-social holometabolous insects

2020 ◽  
Vol 34 (5) ◽  
pp. 659-680 ◽  
Author(s):  
Anh The Than ◽  
Fleur Ponton ◽  
Juliano Morimoto
Keyword(s):  
Population Dynamics ◽  
Life History ◽  
Life History Traits ◽  
Larval Density ◽  
Future Research ◽  
Density Dependent ◽  
Integrative Framework ◽  
Wide Range ◽  
Microbe Interactions ◽  
Host Microbe Interactions

Abstract Population density modulates a wide range of eco-evolutionary processes including inter- and intra-specific competition, fitness and population dynamics. In holometabolous insects, the larval stage is particularly susceptible to density-dependent effects because the larva is the resource-acquiring stage. Larval density-dependent effects can modulate the expression of life-history traits not only in the larval and adult stages but also downstream for population dynamics and evolution. Better understanding the scope and generality of density-dependent effects on life-history traits of current and future generations can provide useful knowledge for both theory and experiments in developmental ecology. Here, we review the literature on larval density-dependent effects on fitness of non-social holometabolous insects. First, we provide a functional definition of density to navigate the terminology in the literature. We then classify the biological levels upon which larval density-dependent effects can be observed followed by a review of the literature produced over the past decades across major non-social holometabolous groups. Next, we argue that host-microbe interactions are yet an overlooked biological level susceptible to density-dependent effects and propose a conceptual model to explain how density-dependent effects on host-microbe interactions can modulate density-dependent fitness curves. In summary, this review provides an integrative framework of density-dependent effects across biological levels which can be used to guide future research in the field of ecology and evolution.

scholarly journals Scientific Methods to Understand Fish Population Dynamics and Support Sustainable Fisheries Management

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 574
Author(s):  
Shewit Gebremedhin ◽  
Stijn Bruneel ◽  
Abebe Getahun ◽  
Wassie Anteneh ◽  
Peter Goethals
Keyword(s):  
Developing Countries ◽  
Population Dynamics ◽  
Life History ◽  
Freshwater Fish ◽  
Life History Traits ◽  
Stock Assessment ◽  
Freshwater Ecosystems ◽  
Sustainable Fisheries ◽  
Fish Stocks ◽  
The World

Fisheries play a significant role in the livelihoods of the world population, while the dependence on fisheries is acute in developing countries. Fisheries are consequently a critical element for meeting the sustainable development (SDG) and FAO goals to reduce poverty, hunger and improve health and well-being. However, 90% of global marine fish stocks are fully or over-exploited. The amount of biologically unsustainable stocks increased from 10% in 1975 to 33% in 2015. Freshwater ecosystems are the most endangered ecosystems and freshwater fish stocks are worldwide in a state of crisis. The continuous fish stock decline indicates that the world is still far from achieving SDG 14 (Life Below Water), FAO’s Blue Growth Initiative goal and SDG 15 (Life on Land, including freshwater systems). Failure to effectively manage world fish stocks can have disastrous effects on biodiversity and the livelihoods and socio-economic conditions of millions of people. Therefore, management strategies that successfully conserve the stocks and provide optimal sustainable yields are urgently needed. However, successful management is only possible when the necessary data are obtained and decision-makers are well informed. The main problem for the management of fisheries, particularly in developing countries, is the lack of information on the past and current status of the fish stocks. Sound data collection and validation methods are, therefore, important. Stock assessment models, which support sustainable fisheries, require life history traits as input parameters. In order to provide accurate estimates of these life history traits, standardized methods for otolith preparation and validation of the rate of growth zone deposition are essential. This review aims to assist researchers and fisheries managers, working on marine and freshwater fish species, in understanding concepts and processes related to stock assessment and population dynamics. Although most examples and case studies originate from developing countries in the African continent, the review remains of great value to many other countries.

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