Estimating population size of the Black-eared Miner, with an assessment of landscape-scale habitat requirements

2005 ◽  
Vol 11 (3) ◽  
pp. 174 ◽  
Author(s):  
Rohan H. Clarke ◽  
Rebecca L. Boulton ◽  
Michael F. Clarke
Keyword(s):  
Population Size ◽  
Large Scale ◽  
Quantitative Methods ◽  
Habitat Degradation ◽  
Regional Scale ◽  
Distance Sampling ◽  
Biosphere Reserve ◽  
Habitat Requirements ◽  
Effective Population ◽  
Southeastern Australia

The decline of the Black-eared Miner Manorina melanotis has been caused primarily by habitat degradation and vegetation clearance. To better direct conservation actions for this species there was a need to assess habitat requirements on a regional-scale and to estimate the population size using quantitative methods. We used vegetation mapping and the current distribution of the Black-eared Miner to determine regional-scale habitat requirements. These findings were combined with the results of distance sampling to provide population estimates. The species is restricted to large tracts of intact mallee in the Murray Mallee of southeastern Australia that have not been burnt for at least 45 years. The density of Black-eared Miners is highest in areas that are dominated by mallee-Triodia associations and have not been intensively grazed. The Bookmark Biosphere Reserve supports an estimated 501 (270-927, 95% CI) colonies, containing 3 758 (2 026-6 954) phenotypically pure Black-eared Miners, 2 255 (1 215-4 170) hybrids and small numbers of Yellow-throated Miners Manorina flavigula. However, the effective population size is considerably smaller (390 Black-eared Miners (210-726) and 234 hybrids (126-433)). due to a skewed adult sex ratio (1 female: 1.81 males) and complex social organization. A smaller population also persists in the Murray Sunset National Park containing 53 (32-85) Black-eared Miner/hybrid colonies. Both populations face a high risk of extinction from large-scale wildfire. The endangered status of the species under IUCN criteria remains warranted.

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 Lingering Impacts of Hurricane Hugo on Rhizophora mangle (Red Mangrove) Population Genetics on St. John, USVI

Diversity ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 65 ◽  
Author(s):  
Bologna ◽  
Campanella ◽  
Restaino ◽  
Fetske ◽  
Lourenco ◽  
...  
Keyword(s):  
Population Size ◽  
Population Analysis ◽  
Biosphere Reserve ◽  
Rhizophora Mangle ◽  
Effective Population ◽  
Island Populations ◽  
Inbreeding Coefficients ◽  
Red Mangrove ◽  
Stochastic Events ◽  
Hurricane Hugo

Stochastic events can have catastrophic effects on island populations through a series of genetic stressors from reduced population size. We investigated five populations of red mangrove (Rhizophora mangle) from St. John, USVI, an UNESCO Biosphere Reserve, which were impacted by Hurricane Hugo in 1989. Our goal was to determine diversity and to ascertain potential population bottlenecks two decades after the event. With the lowest observed heterozygosity, highest inbreeding coefficient, and evidence of a major bottleneck, our results demonstrated that the Great Lameshur mangroves, devastated by Hurricane Hugo, were the least diverse stand of trees. The other four populations from St. John manifested diversity reflecting the vegetation patterns of “fringing” mangrove or “developed forest” characteristics. The two fringing mangrove populations (Hurricane Hole and New Found Bay) evinced low observed heterozygosity and high inbreeding coefficients, while the fully forested sites showed higher heterozygosity and lower inbreeding frequencies. As such, fringing mangroves may be at greater risk to disturbance events and especially susceptible to sea level rise since they do not have room landward to expand. Our pair-wise population analysis indicated genetic similarity between the hurricane-damaged Great Lameshur and Coral Bay population, whose propagules were used in previous restoration attempts and is the geographically closest population. While the effective population size for Great Lameshur Bay places it in risk of genetic dysfunction, future rehabilitation of the site may be possible by the introduction of propagules from other regions of the island. However, recovery will ultimately be contingent upon hydrological connectivity and environmental improvements.

scholarly journals The transformation of the Baltic countries’ political elites: general and specific features

Baltic Region ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 26-39
Author(s):  
V. A. Smirnov
Keyword(s):  
Large Scale ◽  
Quantitative Methods ◽  
Regional Scale ◽  
Political Life ◽  
Political Elites ◽  
Functional Changes ◽  
Political Transformations ◽  
Baltic Countries ◽  
The Baltic ◽  
Elite Recruitment

This research focuses on the features and transformations of power groups and their role in the political life of the societies of the Baltic countries. This article aims to analyse structural and functional changes in the composition of the Baltic political elites after these countries gained independence in the 1990s. The main objective of this research is to reveal the general and the specific in the transformations of Latvian, Lithuanian, and Estonian elites. Changes in the structure of power groups are considered on a sub-regional scale in view of the current Russian-Baltic political interaction. The common and distinctive features in the transformations of Latvian, Lithuanian, and Estonian elites are identified. Quantitative methods of analysis are used to detect trends in the selection of channels and mechanisms of elite recruitment. The study of power groups concentrated on both large-scale socio-political transformations and individual practices. A comprehensive examination of elite transformation in small states such as the Baltics requires the consideration of both domestic and foreign policy aspects. The thesis is put forward that despite some differences between the Baltic States their political elites have undergone very similar transformations since the 1990s. At the time, Baltic elites asserted continuity with pre-war Latvia, Lithuania, and Estonia and detachment from the Soviet past. The 1990s elite struggle for power led to sharp ethnic, linguistic and political divides in Baltic societies. These rifts limit competition between power groups and reduce the ability of political systems to renew themselves. Having reached the ‘back to the West’ goal, Baltic elites replaced it with the idea of ‘Russian threat’. Bridging internal divides, which may weaken the power of the elites, was postponed as a result.

Outbreaks, gene flow and effective population size in the migratory locust,Locusta migratoria: a regional-scale comparative survey

2009 ◽  
Vol 18 (5) ◽  
pp. 792-800 ◽  
Author(s):  
MARIE-PIERRE CHAPUIS ◽  
ANNE LOISEAU ◽  
YANNIS MICHALAKIS ◽  
MICHEL LECOQ ◽  
ALEX FRANC ◽  
...  
Keyword(s):  
Gene Flow ◽  
Population Size ◽  
Effective Population Size ◽  
Locusta Migratoria ◽  
Regional Scale ◽  
Effective Population ◽  
Migratory Locust ◽  
Comparative Survey

Evolutionary genetics of small populations

2017 ◽  
Author(s):  
Richard Frankham ◽  
Jonathan D. Ballou ◽  
Katherine Ralls ◽  
Mark D. B. Eldridge ◽  
Michele R. Dudash ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Size ◽  
Evolutionary Genetics ◽  
Small Population ◽  
Small Populations ◽  
Effective Population ◽  
Genetic Management ◽  
Evolutionary Genetic ◽  
Loss Of Genetic Diversity ◽  
Number Of Individuals

Genetic management of fragmented populations involves the application of evolutionary genetic theory and knowledge to alleviate problems due to inbreeding and loss of genetic diversity in small population fragments. Populations evolve through the effects of mutation, natural selection, chance (genetic drift) and gene flow (migration). Large outbreeding, sexually reproducing populations typically contain substantial genetic diversity, while small populations typically contain reduced levels. Genetic impacts of small population size on inbreeding, loss of genetic diversity and population differentiation are determined by the genetically effective population size, which is usually much smaller than the number of individuals.

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