scholarly journals Biological traits and threats interact to drive extinctions in a simulation study

2020 ◽  
Author(s):  
Filipe Chichorro ◽  
Luís Correia ◽  
Pedro Cardoso
Keyword(s):  
Body Size ◽  
Habitat Degradation ◽  
Extinction Risk ◽  
Empirical Studies ◽  
Empirical Work ◽  
Evolutionary Model ◽  
Dispersal Ability ◽  
Biological Traits ◽  
Habitat Loss And Fragmentation ◽  
Direct Killing

AbstractHow a particular threat influences extinction risk may depend on biological traits. Empirical studies relating threats and traits are needed, but data are scarce, making simulations useful. We implemented an eco-evolutionary model to analyse how five threat types influence the extinction risk of virtual organisms differing in body size, maturity age, fecundity, and dispersal ability. Results show that direct killing mostly affected slow-living and low dispersal organisms. Habitat loss and fragmentation both affected larger and less fecund organisms, but drove contrasting responses according to dispersal ability. Habitat degradation and the introduction of invasive competitors had similar effects, mostly affecting large, fast-living, and highly fecund organisms. Many of the reported results confirm previous studies, while others were never tested, creating new hypotheses for future empirical work.Statement of authorshipFC, LC and PC designed the study, FC implemented the model and ran the statistical analyses. FC and PC wrote the first draft, and all authors contributed substantially to further revisions.

scholarly journals Small population size and low genomic diversity have no effect on fitness in experimental translocations of a wild fish

2019 ◽  
Vol 286 (1916) ◽  
pp. 20191989 ◽  
Author(s):  
M. C. Yates ◽  
E. Bowles ◽  
D. J. Fraser
Keyword(s):  
Genetic Diversity ◽  
Body Size ◽  
Population Size ◽  
Brook Trout ◽  
Habitat Degradation ◽  
Species Conservation ◽  
Empirical Work ◽  
Genomic Diversity ◽  
Effective Population ◽  
Isolated Populations

Little empirical work in nature has quantified how wild populations with varying effective population sizes and genetic diversity perform when exposed to a gradient of ecologically important environmental conditions. To achieve this, juvenile brook trout from 12 isolated populations or closed metapopulations that differ substantially in population size and genetic diversity were transplanted to previously fishless ponds spanning a wide gradient of ecologically important variables. We evaluated the effect of genome-wide variation, effective population size ( N e ), pond habitat, and initial body size on two fitness correlates (survival and growth). Genetic variables had no effect on either fitness correlate, which was determined primarily by habitat (pond temperature, depth, and pH) and initial body size. These results suggest that some vertebrate populations with low genomic diversity, low N e , and long-term isolation can represent important sources of variation and are capable of maintaining fitness in, and ultimately persisting and adapting to, changing environments. Our results also reinforce the paramount importance of improving available habitat and slowing habitat degradation for species conservation.

scholarly journals Towards a Global Framework for Estimating Acclimation and Thermal Breadth that Predicts Risk from Climate Change

2017 ◽  
Author(s):  
Jason R Rohr ◽  
David J. Civitello ◽  
Jeremy M. Cohen ◽  
Elizabeth A. Roznik ◽  
Barry Sinervo ◽  
...  
Keyword(s):  
Climate Change ◽  
Body Size ◽  
Simulation Modeling ◽  
Extinction Risk ◽  
Empirical Work ◽  
Thermal Acclimation ◽  
Theoretical Frameworks ◽  
Thermal Maximum ◽  
Global Extinction ◽  
Body Sizes

Thermal breadth, the range of body temperatures over which organisms perform well, and thermal acclimation, the ability to alter optimal performance temperature and critical thermal maximum or minimum with changing temperatures, reflect the capacity of organisms to respond to temperature variability and are thus crucial traits for coping with climate change. Although there are theoretical frameworks for predicting thermal breadths and acclimation, the predictions of these models have not been tested across taxa, latitudes, body sizes, traits, habitats, and methodological factors. Here, we address this knowledge gap using simulation modeling and empirical analyses of >2,000 acclimation strengths from >500 species using four datasets of ectotherms. After accounting for important statistical interactions, covariates, and experimental artifacts, we reveal that i) acclimation rate scales positively with body size contributing to a negative association between body size and thermal breadth across species and ii) acclimation capacity increases with body size, seasonality, and latitude (to mid-latitudinal regions) and is regularly underestimated for most organisms. Contrary to suggestions that plasticity theory and empirical work on thermal acclimation are incongruent, these findings are consistent with theory on phenotypic plasticity. We further validated our framework by demonstrating that it could predict global extinction risk to amphibian biodiversity from climate change.

scholarly journals Do predatory adult odonates estimate their adult prey odonates’ body size and dispersal ability to proceed with a successful attack?

2021 ◽  
Vol 13 (7) ◽  
pp. 18949-18952
Author(s):  
Tharaka Sudesh Priyadarshana
Keyword(s):  
Body Size ◽  
Hind Wing ◽  
Empirical Studies ◽  
Challenging Behaviors ◽  
Dispersal Ability ◽  
Successful Attack ◽  
Study Results ◽  
Significant Difference ◽  
Similar Body ◽  
Prey Items

Predator-prey encounters are one of the most challenging behaviors that animals engage in and play a key role in structuring trophic linkages within food webs. Empirical studies suggest that predators (except pathogens, parasites, and parasitoids) tend to be larger in body size and have better dispersal ability than their prey items; however, when predators prey upon members of the same taxonomic group, it is unclear whether such relationships exist between predators and their prey items since both groups may have similar body sizes and dispersal abilities. Adult odonates can be used to test this as they prey upon other odonates within the same suborder, family, genus or species, although such records are uncommon. Using a dataset collected from Sri Lanka and India from 2012 to 2020, this study identified three types of predation behaviors between two suborders of Odonata, i.e., (i) Anisoptera (dragonflies) prey upon Anisoptera, (ii) Anisoptera prey upon Zygoptera (damselflies), and (iii) Zygoptera prey upon Zygoptera. There was no evidence of Anisoptera predation by Zygoptera. Study results showed strong evidence that there is a significant difference in body size (i.e., body length) and dispersal ability (i.e., hind-wing length) between adult predatory odonates and adult prey odonates for all three types of predations. This may indicate that predatory odonates estimate other odonate prey precisely to proceed with a successful attack.

scholarly journals Searching for synthetic mechanisms on how biological traits mediate species responses to climate change

2021 ◽  
Vol 21 (3) ◽  
Author(s):  
Fábio Júlio Alves Borges ◽  
Rafael Loyola
Keyword(s):  
Climate Change ◽  
Extinction Risk ◽  
Diet Breadth ◽  
Dispersal Ability ◽  
Tropical Species ◽  
Biological Traits ◽  
Species Vulnerability ◽  
Environment Temperature ◽  
Species Responses ◽  
Different Response

Abstract: Climate change will likely be the most significant challenge faced by species in this century, and species’ ability to cope with climate change depends on their life history and ecological and evolutionary traits. Understanding how these traits mediate species’ responses is beneficial for identifying more vulnerable species or prone to extinction risk. Here, we carried out a literature review describing how four traits commonly used in vulnerability assessments (i.e. clutch size, diet breadth, dispersal ability, and climatic tolerance) may determine species vulnerability. We also portray the possible mechanisms that explain how these traits govern species responses to climate change. The literature suggests different mechanisms operating for the evaluated traits. The mechanism of response to climate change differs between species inhabiting tropical and temperate regions: while species from the temperate areas may respond positively to temperature rise, tropical species may be severely affected. Since ectotherms depend on environment temperature, they are more sensitive and present different response mechanisms from endotherms.

scholarly journals Biological and extrinsic correlates of extinction risk in Chinese lizards

2021 ◽  
Author(s):  
Yuxi Zhong ◽  
Chuanwu Chen ◽  
Yanping Wang
Keyword(s):  
Body Size ◽  
Extinction Risk ◽  
Species Traits ◽  
Geographic Range ◽  
Range Size ◽  
Habitat Specialization ◽  
Mean Annual Precipitation ◽  
Mean Annual Temperature ◽  
Small Range ◽  
Extrinsic Factors

Abstract China is a country with one of the most species rich reptile faunas in the world. However, nearly a quarter of Chinese lizard species assessed by the China Biodiversity Red List are threatened. Nevertheless, to date, no study has explicitly examined the pattern and processes of extinction and threat in Chinese lizards. In this study, we conducted the first comparative phylogenetic analysis of extinction risk in Chinese lizards. We addressed the following three questions: 1) What is the pattern of extinction and threat in Chinese lizards? 2) Which species traits and extrinsic factors are related to their extinction risk? 3) How can we protect Chinese lizards based on our results? We collected data on ten species traits (body size, clutch size, geographic range size, activity time, reproductive mode, habitat specialization, habitat use, leg development, maximum elevation, and elevation range) and seven extrinsic factors (mean annual precipitation, mean annual temperature, mean annual solar insolation, normalized difference vegetation index (NDVI), human footprint, human population density, and human exploitation). After phylogenetic correction, these variables were used separately and in combination to assess their associations with extinction risk. We found that Chinese lizards with small geographic range, large body size, high habitat specialization, and living in high precipitation areas were vulnerable to extinction. Conservation priority should thus be given to species with the above extinction-prone traits so as to effectively protect Chinese lizards. Preventing future habitat destruction should also be a primary focus of management efforts because species with small range size and high habitat specialization are particularly vulnerable to habitat loss.

scholarly journals Global extinction risk for seahorses, pipefishes and their near relatives (Syngnathiformes)

Oryx ◽  
2021 ◽  
pp. 1-10
Author(s):  
Riley A. Pollom ◽  
Gina M. Ralph ◽  
Caroline M. Pollock ◽  
Amanda C.J. Vincent
Keyword(s):  
Threatened Species ◽  
Habitat Degradation ◽  
Extinction Risk ◽  
Conservation Status ◽  
Field Research ◽  
Selective Extraction ◽  
Iucn Red List ◽  
Point Estimate ◽  
Conservation Action ◽  
Data Deficient

Abstract Few marine taxa have been comprehensively assessed for their conservation status, despite heavy pressures from fishing, habitat degradation and climate change. Here we report on the first global assessment of extinction risk for 300 species of syngnathiform fishes known as of 2017, using the IUCN Red List criteria. This order of bony teleosts is dominated by seahorses, pipefishes and seadragons (family Syngnathidae). It also includes trumpetfishes (Aulostomidae), shrimpfishes (Centriscidae), cornetfishes (Fistulariidae) and ghost pipefishes (Solenostomidae). At least 6% are threatened, but data suggest a mid-point estimate of 7.9% and an upper bound of 38%. Most of the threatened species are seahorses (Hippocampus spp.: 14/42 species, with an additional 17 that are Data Deficient) or freshwater pipefishes of the genus Microphis (2/18 species, with seven additional that are Data Deficient). Two species are Near Threatened. Nearly one-third of syngnathiformes (97 species) are Data Deficient and could potentially be threatened, requiring further field research and evaluation. Most species (61%) were, however, evaluated as Least Concern. Primary threats to syngnathids are (1) overexploitation, primarily by non-selective fisheries, for which most assessments were determined by criterion A (Hippocampus) and/or (2) habitat loss and degradation, for which assessments were determined by criterion B (Microphis and some Hippocampus). Threatened species occurred in most regions but more are found in East and South-east Asia and in South African estuaries. Vital conservation action for syngnathids, including constraining fisheries, particularly non-selective extraction, and habitat protection and rehabilitation, will benefit many other aquatic species.

Ovigeny strategy of the parasitic wasp Cosmocomoidea annulicornis (Hymenoptera: Mymaridae): effect of female age, feeding and host availability on reproductive traits

2021 ◽  
pp. 1-8
Author(s):  
Carolina Manzano ◽  
Eduardo G. Virla ◽  
Maria V. Coll Araoz ◽  
Erica Luft-Albarracin
Keyword(s):  
Body Size ◽  
Parasitic Wasp ◽  
Reproductive Potential ◽  
Reproductive Traits ◽  
Egg Load ◽  
Biological Traits ◽  
Potential Fecundity ◽  
Female Age ◽  
Host Availability ◽  
Egg Maturation

Abstract The reproductive traits of the mymarid wasp Cosmocomoidea annulicornis (Ogloblin) (Hymenoptera: Mymaridae) attacking eggs of the sharpshooter Tapajosa rubromarginata (Signoret) (Hemiptera: Cicadellidae) were evaluated under laboratory conditions. Bioassays were carried out to estimate the realized fecundity and egg load of females. The ovigeny index was calculated and different biological traits, such as body size, oöcyte length, gaster length and wing length, were analysed to assess significant associations between these traits and the species fitness. In addition, the effect of host availability and feeding on longevity and potential fecundity throughout life and the effect of female age on egg maturation dynamics were assessed. The results showed that C. annulicornis is a strongly synovigenic species. A positive correlation was found between fecundity and longevity of the females and between body size and oöcyte length. Contrary to expected, body size was not related to fecundity and longevity. Females lived significantly longer in the presence of hosts and honey than when they were host-deprived and honey-fed or both host and honey deprived. Host availability had a significant effect on the amount of eggs laid by C. annulicornis females. Female age was negatively associated with oöcyte length. Furthermore, females were able to mature additional eggs as they aged, nevertheless, when host-deprived, senescent females presented significantly less mature eggs than younger ones, suggesting a possible egg oosorption. These results might contribute to a better understanding of the reproductive potential of this species as a biocontrol agent.

Media portrayals of older employees: a success story?

2014 ◽  
Vol 27 (4) ◽  
pp. 583-597 ◽  
Author(s):  
Martine van Selm ◽  
Beatrice I.J.M. Van der Heijden
Keyword(s):  
Mass Media ◽  
Older Workers ◽  
Longitudinal Research ◽  
Empirical Studies ◽  
Empirical Work ◽  
Corporate Communication ◽  
Content Type ◽  
Media Portrayals ◽  
Older Employees ◽  
Age Related

Purpose – The purpose of this paper is to provide an analysis of how portrayals of older employees in mass media messages can help combating stereotypical beliefs on their employability. Design/methodology/approach – The authors conducted a systematic review of empirical studies on mass media portrayals of older employees in order to show what these reveal about the ways in which their employment status, occupation, job type, or work setting is portrayed. The approach builds upon theory on media portrayals, media effects, and stereotypes of older workers’ employability. Findings – This study shows that older employees in media portrayals, when present at all, are relatively often shown in higher-level professional roles, herewith overall, depicting an image that is positive, yet differs from stereotypical beliefs on their employability that are prevalent in working organizations. Research limitations/implications – Further empirical work is needed to more safely conclude on the prevalence of age-related portrayals of work and employment in mass media. In addition, longitudinal research is called for in order to better understand the possible causes for the way in which older employees are portrayed, as well as effects of age-related stereotyping in mass media and corporate communication outlets over time. Practical implications – This research sparks ideas about how new portrayals of older employees in mass media and corporate communication outlets can contribute to novel approaches to managing an aging and multi-generational workforce. Social implications – This study shows how working organizations can make use of the positive and powerful media portrayals of older employees, in order to activate normal and non-ageist behaviors toward them, and herewith, to increase their life-long employability. Originality/value – This study highlights the role of media portrayals of older employees in combating stereotypes about their employability.

Population Structure

2001 ◽  
Author(s):  
Leonard Nunney
Keyword(s):  
Population Structure ◽  
Genetic Structure ◽  
Empirical Studies ◽  
Good Reason ◽  
Genetic Correlations ◽  
Evolutionary Change ◽  
Dispersal Ability ◽  
The Face ◽  
Family Associations ◽  
Proximity Structure

Population structure is a ubiquitous feature of natural populations that has an important influence on evolutionary change. In the real world, populations are not homogenous units; instead, they develop an internal structure, created by the physical properties of the environment and the biological characteristics of the species (such as dispersal ability). However, our basic ecological and population genetic models generally ignore population structure and focus on randomly mating (panmictic) populations. Such structure can profoundly change the evolution of a population. In fact, the myriad of influences that population structure exerts can only be hinted at in a single chapter. Since an exhaustive review is not possible, I will focus on presenting the conceptual issues linking mathematical models of population structure to empirical studies. To do this, it is useful to recognize two different kinds of population structure that both reflect and influence evolutionary change. The first is genetic structure. This is defined as the nonrandom distribution of genotypes in space and time. Thus, genetic structure reflects the genetic differences that develop among the different components of one or more populations. The second is what I will call proximity structure, defined by the size and composition of the group of neighbors that influence an individual’s fitness. Fitness is commonly influenced by local intraspecific interactions. Perhaps the most obvious example is competition. When individuals compete for some resource, they don’t usually compete equally with every other member of the population; in general, they compete only with a few of the most proximate individuals. These two forms of population structure, genetic structure and proximity structure, provide a foundation for understanding why we have shifted away from viewing populations as homogenous units. For good reason, this is a theme that is explored in many of the other chapters in this book. Genetic structure can develop within a population over a single generation, generally either as a result of local family associations or as a result of spatial variation in selection. For example, limited seed dispersal results in genetic correlations among neighbors even in the face of long-distance pollen movement, due to the clustering of maternal half sibs.

The virtue of narrowing: the fiscal federalism setting

2019 ◽  
pp. 99-128
Author(s):  
Pierre Salmon
Keyword(s):  
Theoretical Analysis ◽  
Fiscal Federalism ◽  
Empirical Studies ◽  
Empirical Work ◽  
Data Sets ◽  
Exact Nature ◽  
Yardstick Competition ◽  
Alternative Approaches ◽  
Short Section

This chapter mainly discusses the empirical work in the domain of local (subcentral) finance involving yardstick competition. It begins with a short section on the systemic novelty introduced by yardstick competition into the theory of fiscal federalism. The central part of the chapter focuses on the empirical arguments developed to probe the presence of yardstick competition and yardstick voting in various data sets. Then, some queries are formulated about the exact nature of what has been established empirically so far. It seems clearly confirmed that some form of yardstick competition or yardstick voting is at work in different settings. That result is important but the findings should not be supposed to validate the game-theoretical analysis or the pure mimicking behavior assumption typically associated with the empirical studies. Alternative approaches are considered toward the end of the chapter.

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