Leveraging A Spatiotemporally Large Dataset to Test Predictions of Life History Theory in Stream Fish Communities

It's All Life History

Purpose: Establishing the way the life history (LH) strategies and gratitude are related to each other. Design/methodology/approach: Life History Theory provides an evolutionary framework for understanding specific developmental paths of species and individuals. There are certain trade- offs during a lifespan of an individual, they must face (for instance, somatic or reproductive effort, quality or quantity of offspring, mating or parenting). Depending on the choices a person makes, they exhibit a slow or a fast life history (LH) strategy. A latent variable underlying a set of solutions (strategy) is called K-Factor and is used to measure individual differences with regard to the pace of one’s LH. People with a slow LH exhibit greater prosociality, tend to form long-term sexual relationships and their sexual maturation is slowed down. On the other hand, gratitude facilitates prosociality and altruism, builds social resources and acts as a moral barometer. In recent years we observe an increasing attention to the issue of gratitude both in academic publications and popular press in various fields including economics, management and organizational sciences. All these disciplines draw from relatively new and contemporarily flourishing field of psychology – positive psychology. We deployed the Gratitude Questionnaire (GQ-6) for the measurement of gratitude and the Mini-K Short Form for the measurement of LH strategies. 197 students took part in the study (138 females, 59 males). Findings: A positive correlation between slow LH strategy and gratitude was found in women. Originality/value: Investigations on the relationship between gratitude and LH strategies show a fragment of the landscape of human personality. Slow LH people seem to be more grateful and thus display more prosocial traits while restraining selfishness which can lead to achieving the delayed social benefits. On the other hand, low-K individuals in organizational context have smaller willingness/ability to reciprocate to their benefactors and to build social bonds. Such individuals presenting exploitative interpersonal style should be detected at the beginning of a selection process by HR specialists. Keywords: life history theory, life history strategies, gratitude, positive psychology, positive psychology interventions in organizations. Category of the paper: research paper.

(Re)appreciating the role of life history in eco‐evolutionary dynamics

AimNon‐native fishes threaten native biodiversity worldwide. Life history traits have been used to predict the risk of establishment for non‐native fish in several regions of the world and parts of the United States, but not yet for Florida despite the elevated risk of establishment in the state due to many invasion pathways and favourable climate. Our goal was to identify which life history traits may be useful for predicting which non‐native freshwater fishes might successfully establish populations in Peninsular Florida.LocationPeninsular Florida, USA.MethodsWe conducted a factor analysis to evaluate 21 life history traits for 125 fishes in three different groups: native fishes, non‐native fish species currently established in Florida and introduced fishes that failed to establish in Florida. We also modelled overall life history traits of those fishes according to the triangular model by Winemiller and Rose to compare overall strategies among the three different groups and tested for significant trait differences between failed and established fishes.ResultsOur analyses of life history traits showed that successful species have a high investment in their offspring and tend to be larger bodied. Parental care was particularly important, with only one of the established species lacking parental care. Triangular life history model results showed that most successfully established species such as those in the family Cichlidae are equilibrium strategists with a high degree of parental care, low‐to‐intermediate fecundity and a larger maturation size.Main conclusionsUnderstanding the life history strategies and traits that aid in the prediction of non‐native fish invasiveness is key for effective risk assessment and management. Further analysis of these traits as predictors of establishment and invasion success is needed, and regional risk assessments of non‐native fishes will benefit from inclusion of several traits highlighted in this study.

Do human ‘life history strategies’ exist?

There is substantial variation in the timing of significant reproductive life events such as menarche and first sexual intercourse. Life history theory explains this variation as an adaptive response to an individual’s environment and it is important to examine how traits within life history strategies affect each other. Here we applied Mendelian randomization (MR) methods to investigate whether there is a causal effect of variation in age at menarche and age at first sexual intercourse (markers or results of exposure to early life adversity) on outcomes related to reproduction, education and risky behaviour in UK Biobank (N = 114 883–181 255). Our results suggest that earlier age at menarche affects some traits that characterize life history strategies including earlier age at first and last birth, decreased educational attainment, and decreased age at leaving education (for example, we found evidence for a 0.26 year decrease in age at first birth per year decrease in age at menarche, 95% confidence interval: -0.34 to -0.17; p < 0.001). We find no clear evidence of effects of age at menarche on other outcomes, such as risk taking behaviour. Age at first sexual intercourse was also related to many life history outcomes, although there was evidence of horizontal pleiotropy which violates an assumption of MR and we therefore cannot infer causality from this analysis. Taken together, these results highlight how MR can be applied to test predictions of life history theory and to better understand determinants of health and social behaviour.

Life history theory is useful for taking an evolutionary approach to individual differences. An individual's life history strategy (LHS), based on life history theory, can be measured using the Arizona Life History Battery or a part of it-the Mini-K-as the K-factor. In this study, I examined two research questions regarding the Japanese version of the Mini-K (i.e., Mini-K-J). First, I assessed the construct validity and invariance between sexes of the Mini-K-J because there existed issues with the factor structure of the original Mini-K. These issues were addressed in the original Mini-K, but not in the Japanese version. In particular, I examined whether the instrument consists of a single higher order factor (K-factor) and whether sex invariance exists in the factor structure, following Richardson et al. Second, I assessed criterion validity of the Mini-K-J. In particular, I examined whether the Mini-K-J could capture fast LHS traits in Japanese undergraduates because the Mini-K-J has been validated only using slow LHS traits. The results showed that (1) the Mini-K-J generated a single higher order factor (i.e., K-factor) and five first-order factors, (2) there existed sex invariance of the factor structure, and (3) the higher order K-factor mean might have a different meaning between sexes. These results predominately support Richardson et al. Further, the higher order K-factor of the Mini-K-J could capture fast LHS personality traits. These results suggest that the Mini-K-J would be useful for future studies related to LHS.

Life history theory predictions for hydrologic filtering of fish assemblages are rarely tested with historical time series data. We retrospectively analyzed flow regime and fish assemblage data from the Sabine River, USA, to test relationships between life history strategies and hydrologic variability altered by impoundment construction. Downstream flow variability, but not magnitude, was altered by completion of Toledo Bend Reservoir (TBR) in 1966. Consistent with life history theory, occurrence of opportunistic strategists declined while equilibrium strategists increased as the fish assemblage was transformed between periods immediately after (1967–1973) and approximately one decade after (1979–1982) completion of TBR. Assemblage transformation was related to decline of opportunistic strategists throughout 250 km of river downstream of TBR. Temporal trajectories for opportunistic and intermediate strategist richness modelled as a function of flow variability converged 12 years postimpoundment. The spatiotemporal scaling of our study is novel among tests of life history theory, and results suggest impoundment-induced alteration to natural hydrologic filtering of fish assemblages can operate on the scale of hundreds of stream kilometres and manifest within approximately one decade.

&lt;em&gt;Abstract&lt;/em&gt;.—The flow regime is considered the primary driver of physical processes in riverine ecosystems; thus we expect that the trait composition of fish assemblages might respond similarly to hydrologic variability, even at broad spatial scales. Here, we test the hypothesis that freshwater fish life history strategies on two continents (southern United States and eastern Australia) converge along gradients of hydrologic variability and primary productivity at the drainage scale. Our results show that the fishes of the United States and Australia conform to the three-dimensional adaptive space arising from the trade-offs among three basic demographic parameters of survival, fecundity, and onset and duration of reproductive life. Species from both continents represent the endpoints in adaptive space defining the periodic (19% versus 33% for the United States and Australia, respectively), opportunistic (69% versus 52%), and equilibrium life history strategies (12% versus 15%). We found evidence that fish life history composition of drainage basins in the two continents have converged across similar gradients of hydrologic variability and productivity despite phylogenetic and historical differences. Moreover, these relationships were largely consistent with predictions from life history theory. Increasing hydrologic variability has promoted the greater prevalence of opportunistic strategists (a strategy that should maximize fitness in environmental settings dominated by unpredictable environmental change) while concurrently minimizing the persistence of periodic-type species (a strategy typically inhabits seasonal, periodically suitable environments). Our study provides a conceptual framework of management options for species in regulated rivers because life history strategies are the underlying determinants for population responses to environmental change and therefore can be used to classify typical population responses to flow alteration or mitigation via environmental flow prescriptions.

The National Longitudinal Study of Adolescent Health data were used to test predictions from life history theory. We hypothesized that (1) in young adulthood an emerging life history strategy would exist as a common factor underlying many life history traits (e.g., health, relationship stability, economic success), (2) both environmental harshness and unpredictability would account for unique variance in expression of adolescent and young adult life history strategies, and (3) adolescent life history traits would predict young adult life history strategy. These predictions were supported. The current findings suggest that the environmental parameters of harshness and unpredictability have concurrent effects on life history development in adolescence, as well as longitudinal effects into young adulthood. In addition, life history traits appear to be stable across developmental time from adolescence into young adulthood.

Life history theory predicts that species with faster life history strategies should be willing to risk their survival more to acquire resources than those with slower life history strategies. Foraging can be a risky behavior and animals generally face a tradeoff between food consumption and predation risk. We predicted that the degree to which animals invest in current versus future reproduction (i.e. life history strategy) would determine how they approach this tradeoff. We manipulated food abundance in wetlands to assess whether life history theory could explain risk taking among females of five duck species with respect to foraging. We found evidence consistent with our prediction based on life history theory; species with a faster life history strategy were willing to engage in riskier behavior, by feeding more intensively, for a greater food reward. Females from species with faster life history strategies devoted 25% more time to feeding when in high food density treatment plots versus control plots. The percentage of time that females from species with slower life history strategies devoted to feeding was not affected by food density. These findings contribute to our understanding of life history theory and represent a possible mechanism to explain differences in life history strategies among species.

Life History theory and social deviance: The mediating role of Executive Function

Life history strategy (LHS) and life history contingencies (LHCs) should theoretically influence the use of exploitative and deceptive resource acquisition strategies. However, little research has been done in this area. The purpose of the present work was to create measures of exploitative strategies and test the predictions of life history theory. Pilot studies developed and validated a behavioral measure of cheating called the Dot Game. The role of individual LHS and LHCs (manipulated via validated story primes) on cheating was investigated in Study 1. Studies 2a through 2c were conducted to develop and validate a self-report measure called the Exploitative and Deceptive Resource Acquisition Strategy Scale (EDRASS). Finally, Study 3 investigated life history and EDRASS. Results indicated that while LHS influences exploitative strategies, life history contingences had little effect. Implications of these findings are discussed.

The hydrologic regime is regarded as the primary driver of freshwater ecosystems, structuring the physical habitat template, providing connectivity, framing biotic interactions, and ultimately selecting for specific life histories of aquatic organisms. In the present study, we tested ecological theory predicting directional relationships between major dimensions of the flow regime and life history composition of fish assemblages in perennial free-flowing rivers throughout the continental United States. Using long-term discharge records and fish trait and survey data for 109 stream locations, we found that 11 out of 18 relationships (61%) tested between the three life history strategies (opportunistic, periodic, and equilibrium) and six hydrologic metrics (two each describing flow variability, predictability, and seasonality) were statistically significant (P < or = 0.05) according to quantile regression. Our results largely support a priori hypotheses of relationships between specific flow indices and relative prevalence of fish life history strategies, with 82% of all significant relationships observed supporting predictions from life history theory. Specifically, we found that (1) opportunistic strategists were positively related to measures of flow variability and negatively related to predictability and seasonality, (2) periodic strategists were positively related to high flow seasonality and negatively related to variability, and (3) the equilibrium strategists were negatively related to flow variability and positively related to predictability. Our study provides important empirical evidence illustrating the value of using life history theory to understand both the patterns and processes by which fish assemblage structure is shaped by adaptation to natural regimes of variability, predictability, and seasonality of critical flow events over broad biogeographic scales.

Predictive models have been used to determine fish species that occur less frequently than expected (decreasers) and those that occur more frequently than expected (increasers) in streams in the eastern U.S. Coupling life history traits with 51 decreaser and 38 increaser fish species provided the opportunity to examine potential mechanisms associated with predicted changes in fish species distributions in eastern streams. We assigned six life history traits – fecundity, longevity, maturation age, maximum total length, parental care, and spawning season duration – to each fish species. Decreaser species were significantly smaller in size and shorter-lived with reduced fecundity and shorter spawning seasons compared to increaser species. Cluster analysis of traits revealed correspondence with a life history model defining equilibrium (low fecundity, high parental care), opportunistic (early maturation, low parental care), and periodic (late maturation, high fecundity, low parental care) end-point strategies. Nearly 50 % of decreaser species were associated with an intermediate opportunistic-periodic strategy, suggesting that abiotic factors such as habitat specialization and streamflow alteration may serve as important influences on life history traits and strategies of decreaser species. In contrast, the percent of increaser species among life history strategy groups ranged from 21 to 32 %, suggesting that life history strategies of increaser species were more diverse than those of decreaser species. This study highlights the utility of linking life history theory to biodiversity to better understand mechanisms that contribute to fish species distributions in the eastern U.S.