scholarly journals The Use of Intraallelic Variability for Testing Neutrality and Estimating Population Growth Rate

Genetics ◽  
2001 ◽  
Vol 158 (2) ◽  
pp. 865-874 ◽  
Author(s):  
Montgomery Slatkin ◽  
Giorgio Bertorelle
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Joint Distribution ◽  
Population Growth Rate ◽  
Marker Locus ◽  
European Population ◽  
Published Data ◽  
Data Sets ◽  
Marker Loci ◽  
Heterozygous Carriers

Abstract To better understand the forces affecting individual alleles, we introduce a method for finding the joint distribution of the frequency of a neutral allele and the extent of variability at closely linked marker loci (the intraallelic variability). We model three types of intraallelic variability: (a) the number of nonrecombinants at a linked biallelic marker locus, (b) the length of a conserved haplotype, and (c) the number of mutations at a linked marker locus. If the population growth rate is known, the joint distribution provides the basis for a test of neutrality by testing whether the observed level of intraallelic variability is consistent with the observed allele frequency. If the population growth rate is unknown but neutrality can be assumed, the joint distribution provides the likelihood of the growth rate and leads to a maximum-likelihood estimate. We apply the method to data from published data sets for four loci in humans. We conclude that the Δ32 allele at CCR5 and a disease-associated allele at MLH1 arose recently and have been subject to strong selection. Alleles at PAH appear to be neutral and we estimate the recent growth rate of the European population to be ∼0.027 per generation with a support interval of (0.017-0.037). Four of the relatively common alleles at CFTR also appear to be neutral but ΔF508 appears to be significantly advantageous to heterozygous carriers.

scholarly journals Contrasting effects of climate on grey heron, malleefowl and barn owl populations

2012 ◽  
Vol 39 (1) ◽  
pp. 7 ◽  
Author(s):  
Maria Boyle ◽  
Jim Hone
Keyword(s):  
Growth Rate ◽  
Population Dynamics ◽  
Population Growth ◽  
Population Growth Rate ◽  
Bird Species ◽  
Barn Owl ◽  
Annual Rainfall ◽  
Future Climate Change ◽  
Published Data ◽  
Grey Heron

Context The population dynamics of many wildlife species are associated with fluctuations in climate. Food and abundance may also influence wildlife dynamics. Aims The present paper aims to evaluate the relative effects of climate on the annual instantaneous population growth rate (r) of the following three bird species: grey heron and barn owl in parts of Britain and malleefowl in a part of Australia. Methods A priori hypotheses of mechanistic effects of climate are derived and evaluated using information theoretic and regression analyses and published data for the three bird species. Climate was measured as the winter North Atlantic Oscillation (NAO) for herons and owls, and rainfall and also the Southern Oscillation Index (SOI) for malleefowl. Key results Population dynamics of grey heron were positively related to the winter NAO, and of malleefowl were positively related to annual rainfall and related in a non-linear manner to SOI. By contrast, population dynamics of barn owl were very weakly related to climate. The best models for the grey heron differed between time periods but always included an effect of the NAO. Conclusions The annual population growth rate of grey heron, malleefowl and barn owl show contrasting relationships with climate, from stronger (heron and malleefowl) to weaker (barn owl). The results were broadly consistent with reported patterns but differed in some details. Interpretation of the effects of climate on the basis of analyses rather than visual assessment is encouraged. Implications Effects of climate differ among species, so effects of future climate change may also differ.

scholarly journals Biological scaling in green algae: the role of cell size and geometry

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Helena Bestová ◽  
Jules Segrestin ◽  
Klaus von Schwartzenberg ◽  
Pavel Škaloud ◽  
Thomas Lenormand ◽  
...  
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Population Growth Rate ◽  
Internal Diffusion ◽  
Scaling Exponent ◽  
Power Scaling ◽  
Nutrient Distribution ◽  
Metabolic Scaling ◽  
Key Factor ◽  
Size And Morphology

AbstractThe Metabolic Scaling Theory (MST), hypothesizes limitations of resource-transport networks in organisms and predicts their optimization into fractal-like structures. As a result, the relationship between population growth rate and body size should follow a cross-species universal quarter-power scaling. However, the universality of metabolic scaling has been challenged, particularly across transitions from bacteria to protists to multicellulars. The population growth rate of unicellulars should be constrained by external diffusion, ruling nutrient uptake, and internal diffusion, operating nutrient distribution. Both constraints intensify with increasing size possibly leading to shifting in the scaling exponent. We focused on unicellular algae Micrasterias. Large size and fractal-like morphology make this species a transitional group between unicellular and multicellular organisms in the evolution of allometry. We tested MST predictions using measurements of growth rate, size, and morphology-related traits. We showed that growth scaling of Micrasterias follows MST predictions, reflecting constraints by internal diffusion transport. Cell fractality and density decrease led to a proportional increase in surface area with body mass relaxing external constraints. Complex allometric optimization enables to maintain quarter-power scaling of population growth rate even with a large unicellular plan. Overall, our findings support fractality as a key factor in the evolution of biological scaling.

Lessons from a century of conservation translocations

2021 ◽  
Author(s):  
Shane D Morris ◽  
Katherine E. Moseby ◽  
Barry W. Brook ◽  
Christopher N. Johnson
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Population Growth Rate ◽  
Historical Context ◽  
Extrinsic Factors ◽  
Global Database ◽  
Terrestrial Vertebrates ◽  
Failure Classification ◽  
High Population Growth ◽  
Number Of Individuals

Translocation—moving individuals for release in different locations—is among the most important conservation interventions for increasing or re-establishing populations of threatened species. However, translocations often fail. To improve their effectiveness, we need to understand the features that distinguish successful from failed translocations. Here, we assembled and analysed a global database of translocations of terrestrial vertebrates (n=514) to assess the effects of various design features and extrinsic factors on success. We analysed outcomes using standardized metrics i.e. a categorical success/failure classification, and population growth rate. Probability of categorical success and population growth rate increased with the total number of individuals released but with diminishing returns above about 20-50 individuals. There has been no increase in numbers released per translocation over time. Positive outcomes—reported success and high population growth—were less likely for translocation in Oceania, possibly because invasive species are a major threat in this region and are difficult to control at translocation sites. Increased rates of categorical reported success and population growth were found for Europe and North America, suggesting the key role of historical context in positive translocation outcomes. Categorical success has increased throughout the 20th century, but that increase may have plateaued at about 75% since about 1990. Our results suggest there is potential for further increase in the success of conservation translocations. This could be best achieved by greater investment in individual projects, as indicated by total number of animals released.

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