Population Size Limits the Coefficient of Variation in Continuous Traits Affected by Proportional Copying Error (and Why This Matters for Studying Cultural Transmission)

2020 ◽  
Author(s):  
L. S. Premo
Keyword(s):  
Population Size ◽  
Coefficient Of Variation ◽  
Cultural Transmission ◽  
Size Limits ◽  
Continuous Traits

Comment—Revised estimates of the bias in the 'minimum number alive' estimator

1992 ◽  
Vol 70 (3) ◽  
pp. 628-631 ◽  
Author(s):  
Murray Efford
Keyword(s):  
Computer Simulation ◽  
Population Size ◽  
Coefficient Of Variation ◽  
Population Estimate ◽  
Negative Bias ◽  
Highly Sensitive ◽  
Minimum Number ◽  
Simulation Results ◽  
Open Populations ◽  
Minimum Numbers

The computer simulation results of Hilborn et al. (R. Hilborn, J. A. Redfield, and C. J. Krebs. 1976. Can. J. Zool. 54: 1019–1024) regarding the bias of the 'minimum number alive' estimator of population size are shown to be in error. Minimum numbers alive are approximately twice as biased as estimated by these authors: for five species of Microtus the negative bias is estimated as 24–45% instead of 10–18%. 'Minimum number alive' differs from the Jolly–Seber population estimate in being particularly sensitive to mean trappability when the coefficient of variation of trappability is constant. Both population estimators are highly sensitive to reduced trappability of unmarked animals. The Jolly–Seber estimator remains the method of choice for open populations, especially if the coefficient of variation in trappability can be minimized.

scholarly journals Population size impacts host–pathogen coevolution

2021 ◽  
Vol 288 (1965) ◽  
Author(s):  
Andrei Papkou ◽  
Rebecca Schalkowski ◽  
Mike-Christoph Barg ◽  
Svenja Koepper ◽  
Hinrich Schulenburg
Keyword(s):  
Population Size ◽  
Finite Population ◽  
Host Population ◽  
Major Influence ◽  
Small Populations ◽  
Selection Dynamics ◽  
Host Pathogen ◽  
Population Sizes ◽  
Size Limits ◽  
Efficiency Of Selection

Ongoing host–pathogen interactions are characterized by rapid coevolutionary changes forcing species to continuously adapt to each other. The interacting species are often defined by finite population sizes. In theory, finite population size limits genetic diversity and compromises the efficiency of selection owing to genetic drift, in turn constraining any rapid coevolutionary responses. To date, however, experimental evidence for such constraints is scarce. The aim of our study was to assess to what extent population size influences the dynamics of host–pathogen coevolution. We used Caenorhabditus elegans and its pathogen Bacillus thuringiensis as a model for experimental coevolution in small and large host populations, as well as in host populations which were periodically forced through a bottleneck. By carefully controlling host population size for 23 host generations, we found that host adaptation was constrained in small populations and to a lesser extent in the bottlenecked populations. As a result, coevolution in large and small populations gave rise to different selection dynamics and produced different patterns of host–pathogen genotype-by-genotype interactions. Our results demonstrate a major influence of host population size on the ability of the antagonists to co-adapt to each other, thereby shaping the dynamics of antagonistic coevolution.

scholarly journals Mid to Late Holocene Population Trends, Culture Change and Marine Resource Intensification in Western Alaska

ARCTIC ◽  
2017 ◽  
Vol 70 (4) ◽  
Author(s):  
Andrew H. Tremayne ◽  
William A. Brown
Keyword(s):  
Population Size ◽  
Culture Change ◽  
Role Models ◽  
Cultural Transmission ◽  
Late Holocene ◽  
Population Pressure ◽  
The Arctic ◽  
Radiocarbon Dates ◽  
Population Crash ◽  
Cultural Traits

The goal of this project is to understand the influence of population size on human adaptation processes and culture change during the Mid to Late Holocene in Western Alaska. We use a database of 1180 radiocarbon dates ranging from 6000 to 1000 14C years BP and drawn from 805 archaeological components in Alaska to construct a proxy record for relative change in regional and Alaskan metapopulation sizes over time. Our analysis indicates that a major population crash coincided with the disappearance of the Arctic Small Tool tradition (ASTt) and the subsequent emergence of the Norton tradition. The ASTt population began to decline around 3600 cal BP, and by 3500 cal BP it had disappeared almost completely from northern tundra habitats, though it persisted in coastal areas in Northwest and Southwest Alaska for another 500 years. The reduction in human population across Alaska after 3600 cal BP appears linked to a reduced carrying capacity that was perhaps driven by a caribou population crash. Such a shock would have increased population pressure and fostered increased reliance on marine resources, precipitating cultural changes associated with an increasingly complex maritime economy. The sharp decline in ASTt population size reduced the number of cultural role models for this population, resulting in the loss of some of the tradition’s characteristic cultural traits, while the influence of neighboring populations in southern Alaska and across the Bering Strait apparently increased, counteracting this attrition of cultural traits. Holistic explanations of the ASTt-Norton transition must take into account population size, ecological adaptation, and cultural transmission processes, as is true for cultural change more generally.

scholarly journals Analysing the Diversification of Cultural Variants using Longitudinal Richness Data

2020 ◽  
Author(s):  
Erik Gjesfjeld ◽  
Enrico R. Crema ◽  
Anne Kandler
Keyword(s):  
Population Size ◽  
Cultural Evolution ◽  
Cultural Transmission ◽  
Population Level ◽  
Diversification Rate ◽  
Future Research ◽  
Time Averaging ◽  
Rate Analysis ◽  
Transmission Modes ◽  
Cultural Data

One of the most significant challenges for cultural evolution is the inference of macroevolutionary patterns from historical and archaeological sources of cultural data. Here, we examine the utility of diversification rate analysis for observing trends in the mode and tempo of cultural evolution using simulated cultural data sets. We explore a range of scenarios in which transmission modes, population size, and innovation rates change over time and generate population-frequency data. From this data, we extract longitudinal richness and further reduce its completeness through time-averaging and random sampling. Given that perfect population-level frequencies can rarely be assumed or even approximated from historical data, these simulated scenarios provide the grounds for exploring the inferential power of longitudinal richness data. Results suggest that diversification rate analysis can identify profiles of underlying changes in population size, innovation rates, and cultural transmission. Furthermore, our results highlight a series of methodological outcomes that can be used to enhance future research into the dynamic patterns of cultural evolution.

Effective Population Size and the Effects of Demography on Cultural Diversity and Technological Complexity

2016 ◽  
Vol 81 (4) ◽  
pp. 605-622 ◽  
Author(s):  
L. S. Premo
Keyword(s):  
Cultural Diversity ◽  
Population Size ◽  
Effective Population Size ◽  
Cultural Transmission ◽  
Effective Population ◽  
Technological Complexity ◽  
Central Tenet ◽  
Empirical Tests ◽  
Census Population Size ◽  
The Relationship

A central tenet of the so-called demographic hypothesis is that larger populations ought to be associated with more diverse and complex toolkits. Recent empirical tests of this expectation have yielded mixed results, leading some to question to what extent changes in population size might explain interesting changes in the prehistoric archaeological record. Here, I employ computer simulation as a heuristic tool to address whether these mixed results reflect deficiencies in the formal models borrowed from population genetics or problems with the generalizations archaeologists have derived from them. I show that two previously published and highly influential models highlight two different effects of demography. My results illustrate how natural selection and cultural selection weaken the relationship between census population size, cultural diversity, and mean skill level, suggesting that one should not expect population size to predict the diversity or complexity of a cultural trait under all conditions. The concept of effective population size is central to understanding why the effects of population size can vary among traits that are passed by different mechanisms of cultural transmission within the same population. In light of these findings, I suggest ways to strengthen (rather than abandon) empirical tests of the demographic hypothesis.

scholarly journals On the absence of a correlation between population size and ‘toolkit size' in ethnographic hunter–gatherers

2018 ◽  
Vol 373 (1743) ◽  
pp. 20170061 ◽  
Author(s):  
Kenichi Aoki
Keyword(s):  
Material Culture ◽  
Population Size ◽  
Cultural Transmission ◽  
Positive Association ◽  
Theoretical Models ◽  
Interdisciplinary Studies ◽  
Apparent Contradiction ◽  
Hunter Gatherers ◽  
Variable Population ◽  
Cultural Gaps

In apparent contradiction to the theoretically predicted effect of population size on the quality/quantity of material culture, statistical analyses on ethnographic hunter–gatherers have shown an absence of correlation between population size and toolkit size. This has sparked a heated, if sometimes tangential, debate as to the usefulness of the theoretical models and as to what modes of cultural transmission humans are capable of and hunter–gatherers rely on. I review the directly relevant theoretical literature and argue that much of the confusion is caused by a mismatch between the theoretical variable and the empirical observable. I then confirm that a model incorporating the appropriate variable does predict a positive association between population size and toolkit size for random oblique, vertical, best-of- K , conformist, anticonformist, success bias and one-to-many cultural transmission, with the caveat that for all populations sampled, the population size has remained constant and toolkit size has reached the equilibrium for this population size. Finally, I suggest three theoretical scenarios, two of them involving variable population size, that would attenuate or eliminate this association and hence help to explain the empirical absence of correlation. This article is part of the theme issue ‘Bridging cultural gaps: interdisciplinary studies in human cultural evolution'.

Conflicting objectives in trophy trout recreational fisheries: evaluating trade-offs using an individual-based model

2011 ◽  
Vol 68 (11) ◽  
pp. 1892-1904 ◽  
Author(s):  
Martín Ignacio García-Asorey ◽  
Gabriela Escati-Peñaloza ◽  
Ana María Parma ◽  
Miguel Alberto Pascual
Keyword(s):  
Population Size ◽  
Size Structure ◽  
Somatic Growth ◽  
Maximum Size ◽  
Minimum Size ◽  
Recreational Fisheries ◽  
Trade Offs ◽  
Conflicting Objectives ◽  
Size Limits ◽  
Harvest Model

Standard fisheries models, based on average population metrics, are inadequate for analyzing recreational fisheries where fishing is size-selective and management objectives are related to preserving population size structure. We developed a framework for policy analysis of size-based harvest strategies in recreational fisheries. The framework combines a mixed-effects body growth model and an individual-based harvest model to describe the relationship of growth, mortality, and size structure. Fishery performance is quantified with indicators directly associated to catch-related components of anglers’ satisfaction: yield (kg), population size, and availability of trophy-size fish. We applied our analyses to the steelhead ( Oncorhynchus mykiss ) fishery in the Santa Cruz River (Patagonia, Argentina). Large declines in trophy-size fish are to be expected at fishing mortalities much too low to cause a sizeable decline in recruitment from virgin values. When somatic growth is density-independent, harvest occurs at the expense of other indicators associated with the quality of fishing experienced by individual anglers. Size limits provide a tool to better accommodate harvest without compromising fishing quality. When preserving population size is favored over preserving trophy-size fish, minimum size limits constitute the best policy overall, whereas maximum size limits are best when the emphasis is on preserving trophy-size fish.

Reduction of spermatogonia and testosterone in rat testes flown on space lab-3

1986 ◽  
Vol 44 ◽  
pp. 248-249
Author(s):  
Delbert E. Philpott ◽  
W. Sapp ◽  
C. Williams ◽  
T. Fast ◽  
J. Stevenson ◽  
...  
Keyword(s):  
Social Interaction ◽  
Social Status ◽  
Population Size ◽  
Physiological Response ◽  
Social Rank ◽  
Reproductive Function ◽  
Testicular Development ◽  
Organ Weights ◽  
Reproductive Maturation ◽  
Metabolic Activities

Space Lab 3 (SL-3) was flown on Shuttle Challenger providing an opportunity to measure the effect of spaceflight on rat testes. Cannon developed the idea that organisms react to unfavorable conditions with highly integrated metabolic activities. Selye summarized the manifestations of physiological response to nonspecific stress and he pointed out that atrophy of the gonads always occurred. Many papers have been published showing the effects of social interaction, crowding, peck order and confinement. Flickinger showed delayed testicular development in subordinate roosters influenced by group numbers, social rank and social status. Christian reported increasing population size in mice resulted in adrenal hypertrophy, inhibition of reproductive maturation and loss of reproductive function in adults. Sex organ weights also declined. Two male dogs were flown on Cosmos 110 for 22 days. Fedorova reported an increase of 30 to 70% atypical spermatozoa consisting of tail curling and/or the absence of a tail.

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