Evolutionary demography of age at last birth: integrating approaches from human behavioural ecology and cultural evolution.
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ABSTRACT:
SUBMITTER: Mattison S
PROVIDER: S-EPMC5812972 | biostudies-literature | 2018 Apr
REPOSITORIES: biostudies-literature
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Project description:1. There is a growing number of empirical reports of environmental change simultaneously influencing population dynamics, life history and quantitative characters. We do not have a well-developed understanding of links between the dynamics of these quantities. 2. Insight into the joint dynamics of populations, quantitative characters and life history can be gained by deriving a model that allows the calculation of fundamental quantities that underpin population ecology, evolutionary biology and life history. The parameterization and analysis of such a model for a specific system can be used to predict how a population will respond to environmental change. 3. Age-stage-structured models can be constructed from character-demography associations that describe age-specific relationships between the character and: (i) survival; (ii) fertility; (iii) ontogenetic development of the character among survivors; and (iv) the distribution of reproductive allocation. 4. These models can be used to calculate a wide range of useful biological quantities including population growth and structure; terms in the Price equation including selection differentials; estimates of biometric heritabilities; and life history descriptors including generation time. We showcase the method through parameterization of a model using data from a well-studied population of Soay sheep Ovis aries. 5. Perturbation analysis is used to investigate how the quantities listed in summary point 4 change as each parameter in each character-demography function is altered. 6. A wide range of joint dynamics of life history, quantitative characters and population growth can be generated in response to changes in different character-demography associations; we argue this explains the diversity of observations on the consequences of environmental change from studies of free-living populations. 7. The approach we describe has the potential to explain within and between species patterns in quantitative characters, life history and population dynamics.
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Project description:Venoms of N. naja and D. russelii individuals of various developmental stages, including neonates (<30 days), juveniles (between 1 to 12 months), and mature individuals (>36 months), were sampled with permission from the state forest department of Karnataka. 226 individuals and 9 clutches were examined, including periodic venom collection (every three months) from the same N. naja and D. russelii juvenile individuals to track ontogenetic changes across time. Freshly collected venoms were flash-frozen in liquid nitrogen, lyophilised and stored at -80° C. Venoms were fractionated using RP-HPLC and SDS-PAGE and subjected to tandem mass spectrometry for toxin identification. The relative abundance of each toxin family were estimated and compared across different developmental stages.
2024-08-10 | PXD046781 | Pride
Project description:The idea that demographic change may spur or slow down technological change has become widely accepted among evolutionary archaeologists and anthropologists. Two models have been particularly influential in promoting this idea: a mathematical model by Joseph Henrich, developed to explain the Tasmanian loss of culture during the Holocene; and an agent-based adaptation thereof, devised by Powell et al. to explain the emergence of modern behaviour in the Late Pleistocene. However, the models in question make rather strong assumptions about the distribution of skills among social learners and about the selectivity of social learning strategies. Here I examine the behaviour of these models under more conservative and, on empirical and theoretical grounds, equally reasonable assumptions. I show that, some qualifications notwithstanding, Henrich's model largely withstands my robustness tests. The model of Powell et al., in contrast, does not--a finding that warrants a fair amount of skepticism towards Powell et al.'s explanation of the Upper Paleolithic transition. More generally, my evaluation of the accounts of Henrich and of Powell et al. helpfully clarify which inferences their popular models do and not support.
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Project description:Inferences about adaptation at specific loci are often exclusively based on the static analysis of DNA sequence variation. Ideally,population-genetic evidence for positive selection serves as a stepping-off point for experimental studies to elucidate the functional significance of the putatively adaptive variation. We argue that inferences about adaptation at specific loci are best achieved by integrating the indirect, retrospective insights provided by population-genetic analyses with the more direct, mechanistic insights provided by functional experiments. Integrative studies of adaptive genetic variation may sometimes be motivated by experimental insights into molecular function, which then provide the impetus to perform population genetic tests to evaluate whether the functional variation is of adaptive significance. In other cases, studies may be initiated by genome scans of DNA variation to identify candidate loci for recent adaptation. Results of such analyses can then motivate experimental efforts to test whether the identified candidate loci do in fact contribute to functional variation in some fitness-related phenotype. Functional studies can provide corroborative evidence for positive selection at particular loci, and can potentially reveal specific molecular mechanisms of adaptation.
| S-EPMC2981648 | biostudies-literature
Project description:BACKGROUND:The invasive garden ant, Lasius neglectus, is the most recently detected pest ant and the first known invasive ant able to become established and thrive in the temperate regions of Eurasia. In this study, we aim to reconstruct the invasion history of this ant in Europe analysing 14 populations with three complementary approaches: genetic microsatellite analysis, chemical analysis of cuticular hydrocarbon profiles and behavioural observations of aggression behaviour. We evaluate the relative informative power of the three methodological approaches and estimate both the number of independent introduction events from a yet unknown native range somewhere in the Black Sea area, and the invasive potential of the existing introduced populations. RESULTS:Three clusters of genetically similar populations were detected, and all but one population had a similar chemical profile. Aggression between populations could be predicted from their genetic and chemical distance, and two major clusters of non-aggressive groups of populations were found. However, populations of L. neglectus did not separate into clear supercolonial associations, as is typical for other invasive ants. CONCLUSION:The three methodological approaches gave consistent and complementary results. All joint evidence supports the inference that the 14 introduced populations of L. neglectus in Europe likely arose from only very few independent introductions from the native range, and that new infestations were typically started through introductions from other invasive populations. This indicates that existing introduced populations have a very high invasive potential when the ants are inadvertently spread by human transport.
| S-EPMC2292682 | biostudies-literature
Project description:Authorship is intended to convey information regarding credit and responsibility for manuscripts. However, while there is general agreement within ecology that the first author is the person who contributed the most to a particular project, there is less agreement regarding whether being last author is a position of significance and regarding what is indicated by someone being the corresponding author on a manuscript. Using an analysis of papers published in American Naturalist, Ecology, Evolution, and Oikos, I found that: (1) the number of authors on papers is increasing over time; (2) the proportion of first authors as corresponding author has increased over time, as has the proportion of last authors as corresponding author; (3) 84% of papers published in 2016 had the first author as corresponding author; and (4) geographic regions differed in the likelihood of having the first (or last) author as corresponding author. I also carried out an online survey to better understand views on last and corresponding authorship. This survey revealed that most ecologists view the last author as the "senior" author on a paper (i.e., the person who runs the research group in which most of the work was carried out), and most ecologists view the corresponding author as the person taking full responsibility for a paper. However, there was substantial variation in views on authorship, especially corresponding authorship. Given these results, I suggest that discussions of authorship have as their starting point that the first author will be corresponding author and the senior author will be last author. I also suggest ways of deciding author order in cases where two senior authors contributed equally.
| S-EPMC5677469 | biostudies-other
Project description:Evolutionary perspectives on menopause have focused on explaining why early reproductive cessation in females has emerged and why it is rare throughout the animal kingdom, but less attention has been given to exploring patterns of diversity in age at natural menopause. In this paper, we aim to generate new hypotheses for understanding human patterns of diversity in this trait, defined as age at final menstrual period. To do so, we develop a multilevel, interdisciplinary framework, combining proximate, physiological understandings of ovarian ageing with ultimate, evolutionary perspectives on ageing. We begin by reviewing known patterns of diversity in age at natural menopause in humans, and highlight issues in how menopause is currently defined and measured. Second, we consider together ultimate explanations of menopause timing and proximate understandings of ovarian ageing. We find that ovarian ageing is highly constrained by ageing of the follicle - the somatic structure containing the oocyte - suggesting that menopause timing might be best understood as a by-product of ageing rather than a facultative adaptation. Third, we investigate whether the determinants of somatic senescence also underpin menopause timing. We show that diversity in age at menopause can be, at least partly, explained by the genetic, ecological and life-history determinants of somatic ageing. The public health implications of rethinking menopause as the by-product rather than the catalyst of biological ageing are discussed.
| S-EPMC7612003 | biostudies-literature
Project description:Recent studies argue that cross-cultural variation in human cooperation supports cultural group selection models of the evolution of large-scale cooperation. However, these studies confound cultural and environmental differences between populations by predominantly sampling one population per society. Here, we test the hypothesis that behavioral variation between populations is driven by environmental differences in demography and ecology. We use a public goods game played with money and a naturalistic measure of behavior involving the distribution of salt, an essential and locally valued resource, to demonstrate significant variation in levels of cooperation across 16 discrete populations of the same small-scale society, the Pahari Korwa of central India. Variation between these populations of the same cultural group is comparable to that found between different cultural groups in previous studies. Demographic factors partly explain this variation; age and a measure of social network size are associated with contributions in the public goods game, while population size and the number of adult sisters residing in the population are associated with decisions regarding salt. That behavioral variation is at least partly contingent on environmental differences between populations questions the existence of stable norms of cooperation. Hence, our findings call for reinterpretation of cross-cultural data on cooperation. Although cultural group selection could theoretically explain the evolution of large-scale cooperation, our results make clear that existing cross-cultural data cannot be taken as empirical support for this hypothesis.
| S-EPMC3167540 | biostudies-literature
Project description:BackgroundFloral nectar is an important determinant of plant-pollinator interactions and an integral component of pollination syndromes, suggesting it is under pollinator-mediated selection. However, compared to floral display traits, we know little about the evolutionary ecology of nectar. Combining a literature review with a meta-analysis approach, we summarize the evidence for heritable variation in nectar traits and link this variation to pollinator response and plant fitness. We further review associations between nectar traits and floral signals and discuss them in the context of honest signalling and targets of selection.ScopeAlthough nectar is strongly influenced by environmental factors, heritable variation in nectar production rate has been documented in several populations (mean h2 = 0.31). Almost nothing is known about heritability of other nectar traits, such as sugar and amino acid concentrations. Only a handful of studies have quantified selection on nectar traits, and few find statistically significant selection. Pollinator responses to nectar traits indicate they may drive selection, but studies tying pollinator preferences to plant fitness are lacking. So far, only one study conclusively identified pollinators as selective agents on a nectar trait, and the role of microbes, herbivores, nectar robbers and abiotic factors in nectar evolution is largely hypothetical. Finally, there is a trend for positive correlations among floral cues and nectar traits, indicating honest signalling of rewards.ConclusionsImportant progress can be made by studies that quantify current selection on nectar in natural populations, as well as experimental approaches that identify the target traits and selective agents involved. Signal-reward associations suggest that correlational selection may shape evolution of nectar traits, and studies exploring these more complex forms of natural selection are needed. Many questions about nectar evolution remain unanswered, making this a field ripe for future research.
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Project description:In the study of cultural evolution, observed among-group affinity patterns reflect the effects of processes such as mutation (e.g. innovation and copying error), between-group interaction (culture flow), drift and selection. As in biology, cultural affinity patterns are often spatially correlated, making it difficult to distinguish between the opposing geographically mediated forces of divergence and interaction, which cause groups to become more distinct or similar over time, respectively. Analogous difficulties are faced by evolutionary biologists examining the relationship between biological affinity and geography, particularly at lower taxonomic levels where the potential for gene flow between lineages is greatest. Tree models are generally used to assess the fit between affinity patterns and models of historical divergence. However, factors driving lineage divergence are often spatially mediated, resulting in tree models that are themselves geographically structured. Here, we showcase a simple method drawn from evolutionary ecology for assessing the relative impact of both geographically mediated processes simultaneously. We illustrate the method using global human craniometric diversity and material culture from the northern coast of New Guinea as example case studies. This method can be employed to quantify the relative importance of history (divergence) and geographically mediated between-group interaction (culture flow) in explaining observed cultural affinity patterns.This article is part of the theme issue 'Bridging cultural gaps: interdisciplinary studies in human cultural evolution'.
| S-EPMC5812967 | biostudies-literature