Experimental evidence that competition and habitat use shape the individual fitness surface

2009 ◽  
Vol 22 (1) ◽  
pp. 97-108 ◽  
Author(s):  
R. CALSBEEK
Keyword(s):  
Habitat Use ◽  
Experimental Evidence ◽  
Individual Fitness ◽  
Fitness Surface ◽  
The Individual

Official Advice Improves Mortgage-Holders’ Perceptions of Switching: Experimental Evidence

2019 ◽  
Author(s):  
Shane Timmons
Keyword(s):  
Interest Rate ◽  
Experimental Evidence ◽  
Consumer Protection ◽  
Policy Development ◽  
Switching Process ◽  
Competitive Markets ◽  
Protection Agency ◽  
Change Perceptions ◽  
Before And After ◽  
The Individual

Encouraging consumers to switch to lower-rate mortgages is important both for the individual consumer’s finances and for functioning competitive markets, but switching rates are low. Given the complexity of mortgages, one potential regulatory intervention that may increase switching rates is to provide independent advice on how to select good mortgage products and how to navigate the switching process. Working with a government consumer protection agency, we conducted an experiment with mortgage-holders to test whether such advice alters perceptions of switching. The experiment tested how (i) the attributes of the offer, (ii) perceptions about the switching process, (iii) individual feelings of competence and (iv) comprehension of the product affect willingness to switch to better offers, both before and after reading the official advice. The advice made consumers more sensitive to interest rate decreases, especially at longer terms. It also increased consumers’ confidence in their ability to select good offers. Overall, the findings imply that advice from policymakers can change perceptions and increase switching rates. Moreover, the experiment demonstrates how lab studies can contribute to behaviourally-informed policy development.

scholarly journals THE EVOLUTION OF MULTIPLE MATING BEHAVIOR BY HONEY BEE QUEENS (APIS MELLIFERA L.)

Genetics ◽  
1980 ◽  
Vol 96 (1) ◽  
pp. 263-273
Author(s):  
Robert E Page
Keyword(s):  
Mating Behavior ◽  
Honey Bee ◽  
Multiple Mating ◽  
Genetic Load ◽  
Individual Level ◽  
Individual Fitness ◽  
Essential Components ◽  
Honey Bee Queens ◽  
The Individual ◽  
Sex Determination System

ABSTRACT A model is presented showing that natural selection operating at the individual level can adequately explain the evolution of multiple mating behavior by honey bee queens. Group selection need not be invoked. The fitness of a given female genotype is a function of the number of sex alleles in the population, the number of matings by an individual female and the specific parameters that determine the relationship of brood viability to individual fitness. Even though the exact relationship is not known, it is almost certainly not linear. A nonlinear relationship between worker brood viability and fitness and a significant genetic load associated with the sex-determination system in honey bees are the essential components of this model.

scholarly journals Avoidance of Contaminated Food Correlates With Low Protozoan Infection in Bonobos

2021 ◽  
Vol 9 ◽  
Author(s):  
Cécile Sarabian ◽  
Raphaël Belais ◽  
Andrew J. J. MacIntosh
Keyword(s):  
Infectious Agent ◽  
Oral Route ◽  
Behavioral Experiments ◽  
Food Items ◽  
Individual Fitness ◽  
Behavioral Adaptations ◽  
Trade Offs ◽  
Protozoan Infection ◽  
Contaminated Food ◽  
The Individual

Intense selection pressure from parasites on free-living animals has resulted in behavioral adaptations that help potential hosts avoid sources of infection. In primates, such “behavioral immunity” is expressed in different contexts and may vary according to the ecology of the host, the nature of the infectious agent, and the individual itself. In this study, we investigated whether avoidance of contaminated food was associated with reduced parasite infection in sanctuary-housed bonobos. To do this, we used bonobos’ responses to soil- and fecally-contaminated food in behavioral experiments, and then compared the results with an estimate of protozoan infection across individuals. We found that avoidance of contaminated food correlated negatively with Balantioides coli infection, a potentially pathogenic protozoan transmitted through the fecal-oral route. The association between avoidance responses and parasitism were most evident in experiments in which subjects were offered a choice of food items falling along a gradient of fecal contamination. In the case of experiments with more limited options and a high degree of contamination, most subjects were averse to the presented food item and this may have mitigated any relationship between feeding decisions and infection. In experiments with low perceived levels of contamination, most subjects consumed previously contaminated food items, which may also have obscured such a relationship. The behavioral immunity observed may be a consequence of the direct effects of parasites (infection), reflecting the first scale of a landscape of disgust: individual responses. Indirect effects of parasites, such as modulation of feeding decisions and reduced social interactions—and their potential trade-offs with physiological immunity—are also discussed in light of individual fitness and primate evolution. This study builds on previous work by showing that avoidance behaviors may be effective in limiting exposure to a wide diversity of oro-fecally transmitted parasites.

scholarly journals An integrative skeletal and paleogenomic analysis of prehistoric stature variation suggests relatively reduced health for early European farmers

2021 ◽  
Author(s):  
Stephanie Marciniak ◽  
Christina Bergey ◽  
Ana Maria Silva ◽  
Agata Hałuszko ◽  
Mirosław Furmanek ◽  
...  
Keyword(s):  
Iron Age ◽  
Secondary Analysis ◽  
Skeletal Remains ◽  
Upper Paleolithic ◽  
Long Bone ◽  
Individual Fitness ◽  
Transition To Agriculture ◽  
Early Farmers ◽  
The Individual ◽  
Agricultural Transitions

Human culture, biology, and health were shaped dramatically by the onset of agriculture ~12,000 years before present (BP). Subsistence shifts from hunting and gathering to agriculture are hypothesized to have resulted in increased individual fitness and population growth as evidenced by archaeological and population genomic data alongside a simultaneous decline in physiological health as inferred from paleopathological analyses and stature reconstructions of skeletal remains. A key component of the health decline inference is that relatively shorter statures observed for early farmers may (at least partly) reflect higher childhood disease burdens and poorer nutrition. However, while such stresses can indeed result in growth stunting, height is also highly heritable, and substantial inter-individual variation in the height genetic component within a population is typical. Moreover, extensive migration and gene flow were characteristics of multiple agricultural transitions worldwide. Here, we consider both osteological and ancient DNA data from the same prehistoric individuals to comprehensively study the trajectory of human stature variation as a proxy for health across a transition to agriculture. Specifically, we compared "predicted" genetic contributions to height from paleogenomic data and "achieved" adult osteological height estimated from long bone measurements on a per-individual basis for n=160 ancient Europeans from sites spanning the Upper Paleolithic to the Iron Age (~38,000-2,400 BP). We found that individuals from the Neolithic were shorter than expected (given their individual polygenic height scores) by an average of -4.47 cm relative to individuals from the Upper Paleolithic and Mesolithic (P=0.016). The average osteological vs. expected stature then increased relative to the Neolithic over the Copper (+2.67 cm, P=0.052), Bronze (+3.33 cm, P=0.032), and Iron Ages (+3.95 cm, P=0.094). These results were partly attenuated when we accounted for genome-wide genetic ancestry variation in our sample (which we note is partly duplicative with the individual polygenic score information). For example, in this secondary analysis Neolithic individuals were -3.48 cm shorter than expected on average relative to individuals from the Upper Paleolithic and Mesolithic (P=0.056). We also incorporated observations of paleopathological indicators of non-specific stress that can persist from childhood to adulthood in skeletal remains (linear enamel hypoplasia, cribra orbitalia, and porotic hyperostosis) into our model. Overall, our work highlights the potential of integrating disparate datasets to explore proxies of health in prehistory.

scholarly journals Major Evolutionary Transitions in Social Insects, the Importance of Worker Sterility and Life History Trade-Offs

2021 ◽  
Vol 9 ◽  
Author(s):  
Abel Bernadou ◽  
Boris H. Kramer ◽  
Judith Korb
Keyword(s):  
Life History ◽  
Social Insects ◽  
Division Of Labour ◽  
Evolutionary Transitions ◽  
Individual Level ◽  
Individual Fitness ◽  
Trade Offs ◽  
Group Members ◽  
The Individual ◽  
Worker Sterility

The evolution of eusociality in social insects, such as termites, ants, and some bees and wasps, has been regarded as a major evolutionary transition (MET). Yet, there is some debate whether all species qualify. Here, we argue that worker sterility is a decisive criterion to determine whether species have passed a MET (= superorganisms), or not. When workers are sterile, reproductive interests align among group members as individual fitness is transferred to the colony level. Division of labour among cooperating units is a major driver that favours the evolution of METs across all biological scales. Many METs are characterised by a differentiation into reproductive versus maintenance functions. In social insects, the queen specialises on reproduction while workers take over maintenance functions such as food provisioning. Such division of labour allows specialisation and it reshapes life history trade-offs among cooperating units. For instance, individuals within colonies of social insects can overcome the omnipresent fecundity/longevity trade-off, which limits reproductive success in organisms, when increased fecundity shortens lifespan. Social insect queens (particularly in superorganismal species) can reach adult lifespans of several decades and are among the most fecund terrestrial animals. The resulting enormous reproductive output may contribute to explain why some genera of social insects became so successful. Indeed, superorganismal ant lineages have more species than those that have not passed a MET. We conclude that the release from life history constraints at the individual level is a important, yet understudied, factor across METs to explain their evolutionary success.

scholarly journals Sex ratio and sexual selection in wormshrimps (Crustacea, Amphipoda, Ingolfiellidea)

2006 ◽  
Vol 75 (03-04) ◽  
pp. 189-194 ◽  
Author(s):  
Ronald Vonk ◽  
Vincent Nijman
Keyword(s):  
Sexual Selection ◽  
Sexual Dimorphism ◽  
Sex Ratio ◽  
Habitat Use ◽  
Individual Species ◽  
Small Populations ◽  
Secondary Sexual Characters ◽  
Elusive Species ◽  
The Individual ◽  
Secondary Sexual

Small populations of several species of the groundwater dwelling amphipod genus Ingolfiella are found in caves, wells, seabottoms, beaches and riverbed interstitial habitats. To gain insight in the socio-ecology of these elusive species, we used data from collected specimens to explore the relationships between sexratios, display of secondary sexual characters and other morphological features, and habitat use. We extracted data on the sex ratios and the presence-absence of secondary sexual characters of 13 species from the literature and through examination of museum material. We found a clearly skewed sex ratio with a preponderance of females, both in the individual species as in the genus as a whole. However, sex ratio and the display of secondary sexual characters were not correlated, nor did these characters correlate with the amount of sexual dimorphism. It remains unknown why so many ingolfiellids have evolved these costly features.

Correlates and consequences of injury in a large, predatory stream salamander (Dicamptodon tenebrosus)

2014 ◽  
Vol 35 (1) ◽  
pp. 107-116
Author(s):  
Robin G. Munshaw ◽  
W.I. Atlas ◽  
W.J. Palen ◽  
Danielle M. Courcelles ◽  
Zachary L. Monteith
Keyword(s):  
Pacific Northwest ◽  
Positive Impact ◽  
Interspecific Interactions ◽  
Strong Support ◽  
Weight Of Evidence ◽  
Individual Fitness ◽  
Model Selection Approach ◽  
Dicamptodon Tenebrosus ◽  
Conspecific Aggression ◽  
The Individual

Conspecific aggression is an important factor structuring population dynamics through intra- and interspecific interactions, but is rarely studied in un-manipulated populations. In this study, we evaluated rates of injury as a proxy for conspecific aggression using a depletion survey of predatory coastal giant salamanders (Dicamptodon tenebrosus) in a tributary of the South Fork Eel River, California. We tested a range of hypotheses including a suite of environmental and biotic factors for the rate of injury in a population by using an AIC model-selection approach that examined the weight of evidence for individual models. We examined both the probability of a given individual being injured, and the proportion of individuals within a given study pool being injured. We found strong support for models including salamander size, density of young-of-the-year steelhead, and density of the largest size-class of salamander as factors positively influencing the rate of injury at both the individual and habitat levels. We also found that density of older steelhead (1+ steelhead) had a strong, but highly variable positive impact on frequency of injury. This study shows that both conspecific and heterospecific factors influence intraspecific aggression for the dominant salamander throughout coastal Pacific Northwest streams. Our methodology demonstrates a non-manipulative approach to identifying correlates of natural injury in a cryptic species of amphibian. More work is needed to determine how these factors directly and indirectly influence the spatial distribution, individual fitness, and dynamics of salamander populations within streams.

scholarly journals Ordering Strategy Analysis of Prefabricated Component Manufacturer in Construction Supply Chain

2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Hongxiong Yang ◽  
Jacky K. H. Chung ◽  
Yuhong Chen ◽  
Yifan Pan ◽  
Zhiling Mei ◽  
...  
Keyword(s):  
Supply Chain ◽  
Fitness Function ◽  
Construction Material ◽  
Optimal Order ◽  
Cost Models ◽  
Inventory Cost ◽  
Strategy Analysis ◽  
Individual Fitness ◽  
Eoq Model ◽  
The Individual

Firstly, the characteristics and present situations of the prefabricated construction supply chain are analyzed; inventory cost models for construction material of every phase order, one-off order, and fractionated order are built based on traditional EOQ model and construction supply chain theory. Next, the order decision is represented in binary numbers 0 and 1, in which 0 stands for “no order” and 1 for “order.” The analysis uses the genetic algorithm, sets the objective function, and undergoes testing and assessing the individual fitness function, encoding, decoding, crossover, mutation, and selecting parameter. Moreover, inventory cost of construction supply chain is processed and optimized in Matlab. The research establishes a research paradigm on supply chain management of component manufacturing and materials supply. This study concludes the ordering strategy on construction material, identifies the optimal order points and order batches, and provides recommendations for further research.

scholarly journals Identifying Causes of Social Evolution: Contextual Analysis, the Price Approach, and Multilevel Selection

2021 ◽  
Vol 9 ◽  
Author(s):  
Christoph Thies ◽  
Richard A. Watson
Keyword(s):  
Kin Selection ◽  
Causal Structure ◽  
Multilevel Selection ◽  
Contextual Analysis ◽  
Price Equation ◽  
Evolutionary Transitions ◽  
Selection Theory ◽  
Individual Fitness ◽  
Multilevel Selection Theory ◽  
The Individual

Kin selection theory and multilevel selection theory are distinct approaches to explaining the evolution of social traits. The latter claims that it is useful to regard selection as a process that can occur on multiple levels of organisation such as the level of individuals and the level of groups. This is reflected in a decomposition of fitness into an individual component and a group component. This multilevel view is central to understanding and characterising evolutionary transitions in individuality, e.g., from unicellular life to multicellular organisms, but currently suffers from the lack of a consistent, quantifiable measure. Specifically, the two major statistical tools to determine the coefficients of such a decomposition, the multilevel Price equation and contextual analysis, are inconsistent and may disagree on whether group selection is present. Here we show that the reason for the discrepancies is that underlying the multilevel Price equation and contextual analysis are two non-equivalent causal models for the generation of individual fitness effects (thus leaving different “remainders” explained by group effects). While the multilevel Price equation assumes that the individual effect of a trait determines an individual's relative success within a group, contextual analysis posits that the individual effect is context-independent. Since these different assumptions reflect claims about the causal structure of the system, the correct approach cannot be determined on general theoretical or statistical grounds but must be identified by experimental intervention. We outline interventions that reveal the underlying causal structure and thus facilitate choosing the appropriate approach. We note that kin selection theory with its focus on the individual is immune to such inconsistency because it does not address causal structure with respect to levels of organisation. In contrast, our analysis of the two approaches to measuring group selection demonstrates that multilevel selection theory adds meaningful (falsifiable) causal structure to explain the sources of individual fitness and thereby constitutes a proper refinement of kin selection theory. Taking such refined causal structure into account seems indispensable for studying evolutionary transitions in individuality because these transitions are characterised by changes in the selection pressures that act on the respective levels.

The imitation dilemma: can parrots maintain their vocal individuality when imitating conspecifics?

Behaviour ◽  
2019 ◽  
Vol 156 (5-8) ◽  
pp. 787-814 ◽  
Author(s):  
Heidi M. Thomsen ◽  
Thorsten J.S. Balsby ◽  
Torben Dabelsteen
Keyword(s):  
Social Systems ◽  
Social Contexts ◽  
Acoustic Parameters ◽  
Strong Basis ◽  
Vocal Individuality ◽  
Individual Fitness ◽  
Vocal Imitation ◽  
Contact Calls ◽  
Individual Distinctiveness ◽  
The Individual

Abstract Many species of parrots live in fission–fusion social systems, characterised by frequent changes in flock composition. In these systems, the ability to selectively choose flock members is essential in order to maximise individual fitness. As a result, most species of parrots have individual distinctive contact calls that mediate the formation of groups during fission and fusion events. However, in vocal interactions during fission and fusion events, individuals will modify the fine-scale structure of their contact calls in a manner that sometimes will result in imitation of the contact calls of another individual, potentially altering or weakening the individual distinctiveness of contact calls. This presents parrots with an interesting dilemma. Here we present a study investigating the effect of vocal modification during interactions, including vocal imitation, on the individual distinctiveness and sex-specific differences of contact calls from ten captive bred peach-fronted conures (Eupsittula aurea). In order to determine if vocal individual- and sex distinctiveness persists in contact calls that are modified to that of another individual, we compared nine acoustic parameters from spontaneous (baseline) contact calls and contact calls emitted as response to a playback stimulus. Although modified, all acoustic parameters remained individually distinctive when the focal individuals interacted with the playback stimulus. These results provide a strong basis for discriminating between calls from different individuals across several social contexts, which could play an important role in mediating selective associations between individual peach-fronted conures during fission and fusion events.

Sign in / Sign up

Export Citation Format

Share Document