scholarly journals Non-random distribution of individual genetic diversity along an environmental gradient

2009 ◽  
Vol 364 (1523) ◽  
pp. 1543-1554 ◽  
Author(s):  
Mélody Porlier ◽  
Marc Bélisle ◽  
Dany Garant

Improving our knowledge of the links between ecology and evolution is especially critical in the actual context of global rapid environmental changes. A critical step in that direction is to quantify how variation in ecological factors linked to habitat modifications might shape observed levels of genetic variability in wild populations. Still, little is known on the factors affecting levels and distribution of genetic diversity at the individual level, despite its vital underlying role in evolutionary processes. In this study, we assessed the effects of habitat quality on population structure and individual genetic diversity of tree swallows ( Tachycineta bicolor ) breeding along a gradient of agricultural intensification in southern Québec, Canada. Using a landscape genetics approach, we found that individual genetic diversity was greater in poorer quality habitats. This counter-intuitive result was partly explained by the settlement patterns of tree swallows across the landscape. Individuals of higher genetic diversity arrived earlier on their breeding grounds and settled in the first available habitats, which correspond to intensive cultures. Our results highlight the importance of investigating the effects of environmental variability on individual genetic diversity, and of integrating information on landscape structure when conducting such studies.

Author(s):  
Jinbao Zhang ◽  
Jaeyoung Lee

Abstract This study has two main objectives: (i) to analyse the effect of travel characteristics on the spreading of disease, and (ii) to determine the effect of COVID-19 on travel behaviour at the individual level. First, the study analyses the effect of passenger volume and the proportions of different modes of travel on the spread of COVID-19 in the early stage. The developed spatial autoregressive model shows that total passenger volume and proportions of air and railway passenger volumes are positively associated with the cumulative confirmed cases. Second, a questionnaire is analysed to determine changes in travel behaviour after COVID-19. The results indicate that the number of total trips considerably decreased. Public transport usage decreased by 20.5%, while private car usage increased by 6.4%. Then the factors affecting the changes in travel behaviour are analysed by logit models. The findings reveal significant factors, including gender, occupation and travel restriction. It is expected that the findings from this study would be helpful for management and control of traffic during a pandemic.


Behaviour ◽  
2015 ◽  
Vol 152 (10) ◽  
pp. 1291-1306 ◽  
Author(s):  
A.D. Kelley ◽  
M.M. Humphries ◽  
A.G. McAdam ◽  
Stan Boutin

Both juvenile and adult animals display stable behavioural differences (personality), but lifestyles and niches may change as animals mature, raising the question of whether personality changes across ontogeny. Here, we use a wild population of red squirrels to examine changes in activity and aggression from juvenile to yearling life stages. Personality may change at the individual level (individual stability), population level (mean level stability), and relative to other individuals (differential stability). We calculated all three types of stability, as well as the structural stability of the activity–aggression behavioural syndrome. Within individuals, both activity and aggression scores regressed towards the mean. Differential stability was maintained for activity, but not aggression. Structural stability was maintained; however, the activity–aggression correlation increased in squirrels that gained territories later in the season. These results suggest that personality undergoes some changes as animals mature, and that the ontogeny of personality can be linked to environmental changes.


2019 ◽  
Author(s):  
Matthew M Brooks ◽  
Tom Mueller

Mobile home residence in the United States is associated with negative social, economic, and health related outcomes. However, while research on mobile home residence at the individual level has been performed, a geographic understanding of mobile home prevalence in the United States remains absent from the literature. Therefore, the purpose of our analysis was to evaluate the county-level drivers of mobile home prevalence in the continental United States in 2015. The influence of five groups of variables – demographic, economic, housing, industry and occupation, and natural amenities – were assessed in a series of nested OLS regressions. Additionally, the full model was run as a spatial lag regression to control for spatial autocorrelation. Our results indicate that the primary drivers of mobile home prevalence in U.S. counties were the percent of population in near poverty, the labor force


Author(s):  
Diane C. Bates

This chapter contributes to the explanation to how environmental migrants are ‘selected’ at the individual and small group level. It argues that individual decisions to migrate depend on the type of environmental change. The author distinguishes between sudden onset environmental problems (e.g. natural disasters) and slow onset environmental problems (e.g. climate change). Sudden onsets make push factors more important- They give migrants less power over their decision to migrate, and therefore include more vulnerable population groups. On the contrary, slow onset events create opportunities for individual agency. Governance can play an important role as it can influence migration and environmental change, especially on the local and state level. The author argues that democratic governance arrangements confer agency to individuals and non-democratic governance delimits it. Moreover, the management of sudden onsets in the short run can be more effective in non-democratic governance, while slow onset environmental changes call for democratic governance arrangements.


2020 ◽  
Author(s):  
Pamela Vega-Polo ◽  
Maria M. Cobo ◽  
Andrea Argudo ◽  
Bernardo Gutierrez ◽  
Jennifer Rowntree ◽  
...  

AbstractThe Ecuadorian páramo, a high altitude tundra-like ecosystem, is a unique source of various ecosystem services and distinct biodiversity. Anthropogenic activities are associated with its fragmentation, which alters ecological factors and directly threatens resident species. Vaccinium floribundum Kunth., commonly known as Andean blueberry or mortiño, is a wild shrub endemic to the Andean region and highly valued in Ecuador for its berries, which are widely used in food preparations and hold an important cultural value. Since it is a wild species, mortiño could be vulnerable to environmental changes, resulting in a reduction of the size and distribution of its populations. To evaluate the extent of these effects on the mortiño populations, we assessed the genetic diversity and population structure of the species along the Ecuadorian highlands. We designed and developed a set of 30 homologous SSR markers and used 16 of these to characterize 100 mortiño individuals from 27 collection sites. Our results revealed a high degree of genetic diversity (HE=0.73) for the Ecuadorian mortiño, and a population structure analyses suggested the existence of distinct genetic clusters present in the northern, central and southern highlands. A fourth, clearly differentiated cluster was also found and included individuals from locations at higher elevations. We suggest that the population structure of the species could be explained by an isolation-by-distance model and can be associated to the geological history of the Andean region. Our results suggest that elevation could also be a key factor in the differentiation of mortiño populations. This study provides an extensive overview of the species across its distribution range in Ecuador, contributing to a better understanding of its conservation status. These results can assist the development of conservation programs for this valuable biological and cultural resource and for the páramo ecosystems as a whole.


Author(s):  
Yogesk K. Dwivedi

This chapter empirically examines factors affecting the adoption of broadband in the developing countries of Bangladesh and the Kingdom of Saudi Arabia (KSA). In the case of Bangladesh, attitudinal, normative, and control factors—discussed in the UK case study in Division I of this book—were used and adapted in order to provide insights about broadband adopters and non-adopters within the developing nations. In order to examine the adoption of broadband in the KSA, a number of variables were employed, which also included some of the variables discussed in the UK case study in Division I. As the Internet was introduced comparatively late in Bangladesh (in 1996), in early 2004 the total penetration of Internet within the country was only 0.25 percent (Totel, 2004). It was suggested that the major obstacles associated with low Internet penetration were the low economic status and still-developing infrastructure within the country (Totel, 2004). A recent media report further emphasised that “Bangladesh is not anywhere on the global broadband map, but it is doing its best to get online. Local service provider, DNS SatComm has started deploying fixed wireless gear from Cambridge Broadband and will offer access to government offices, and other commercial entities” (Malik, 2005). It has also been suggested that Internet connection is slow and costly and not affordable by the general public (Hossain, 2004). Given the situations of Bangladesh in terms of demography, telecommunication infrastructure, and affordability of Internet by people, it was felt that understanding factors including cost of Internet access and subscription affecting consumer adoption might help to encourage further diffusion of high speed Internet. In the KSA, the Internet has taken some time to diffuse and is therefore seen as a relatively new technology. The KSA first started with dial up connections and then moved on to adopt broadband and satellite connections to provide better data communication services to its citizens. However, even with the availability of broadband technology, the rate of adoption is considered to be relatively poor in comparison to other developed countries such as the UK, as well as newly industrialised leading broadband users, such as South Korea (Oh et al., 2003). This poor connectivity is often claimed to be caused by website filtration in the region. Consequently, broadband adoption has been slower than expected in the region. Furthermore, a survey of existing literature on broadband adoption suggests that although both macro and micro level studies were conducted in order to understand the deployment of broadband in the developed world and leading countries such as South Korea, none of these studies focus upon developing countries, such as Bangladesh and the KSA. Although this could be attributed to the slow infrastructure development and low rate of adoption within the two countries, this has provided the motivation for undertaking exploratory research in order to develop an understanding of the perceptions of consumers regarding broadband adoption in these developing nations. Thus, this chapter aims to explore the reasons for the slow adoption of broadband in Bangladesh and the KSA by examining the individual level factors affecting broadband uptake in both cases. The research will thereby seek to adapt the individual level factors from the UK case study (Division I) and attempt to examine if and why the adapted factors affect consumers’ attitudes towards the adoption of broadband in the countries. The chapter begins with a brief discussion of the theoretical basis and variables employed to examine broadband adoption. This is followed by a brief discussion of the utilized research methods. The findings are then presented and discussed. Finally, a conclusion to the chapter is provided.


1997 ◽  
Vol 54 (10) ◽  
pp. 2235-2246 ◽  
Author(s):  
C LePage ◽  
P Cury

A spatially explicit individual-based model (IBM) helps to explain how two reproductive strategies, described as obstinate and opportunist, may be acting at the population level. Factors such as the spatial structure and the dynamics of the environment, the shape of the reproductive function, and spawning season duration are considered. Five simulations are presented to explore the importance of these factors in the success of two reproductive strategies experiencing in a first step, a constant, and in a second step, a changing environment. Simulations show that the obstinate strategy is characterized by high inertia and mainly selects optimal environmental conditions in the long term, whereas the opportunist strategy maintains diversity in site choice and allows the individual to explore environmental variability. Under drastic environmental changes, only a population combining both strategies avoids extinction. A low percentage of opportunists (about 1%) coupled with a high proportion of obstinates (about 99%) ensure population viability. Similar percentages have been observed in nature for philopatric species. The respective percentages of inertia and innovation that are needed in the functioning of natural systems are discussed.


2015 ◽  
Vol 65 (2) ◽  
pp. 299-323 ◽  
Author(s):  
Nádia Simões ◽  
Nuno Crespo ◽  
José Castro Pinto

Based on a micro-level approach and using data from the European Working Conditions Survey, covering 27 countries, we analyse the determinants of job quality. With cluster analysis applied to 11 dimensional indices, we form three homogeneous country groups and identify, by estimating twice-censored Tobit models, the main determinant factors affecting the individual level of job quality in each group. We verify the relevance of variables related to worker characteristics, firm characteristics, and the country in which the individual works. Among worker characteristics, education and employment status are the factors with the highest impact on job quality, while the economic sector is the most important firm characteristic. The results suggest the existence of important differences among groups regarding the magnitude of the impact of some factors. The highest dissimilarities are found between the group with better jobs (Nordic countries plus Belgium) and the group with lower quality jobs (Central and Eastern European countries plus Portugal and Greece). Variables related to age, education, dimension of the firm, and economic sector are those in which more heterogeneity is found among the groups.


2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Eshetu E. Chaka ◽  
Peng Bao

Introduction. Maternal mortality continues to be a major public health and development challenge in Africa even after the permissible commitment of the international community. Although the use of skilled delivery care is the key intervention and is effective to lower maternal mortality rates, it is still at a lower proportion. The study is aimed at investigating the individual- and community level factors affecting the use of skilled delivery care among those women who had received adequate antenatal care. Materials and Methods. Data were extracted from the 2016 Ethiopian Demographic and Health Survey on women aged 15-49 years and gave birth within five years prior to the survey ( N = 957 ). Multilevel logistic regression model with two levels were fitted to assess the influence of the individual- and community-level factors on the use of skilled delivery care. Results. Women who were exposed to media were more likely to use skilled delivery care ( OR = 1.81 ; 95% CI: 1.20-2.74). Having six or more birth order ( OR = 0.33 ; 95% CI: 0.16-0.69) and residing in rural areas ( OR = 0.40 ; 95% CI: 0.21-0.79) were associated with less likelihood use of skilled delivery care. Attaining primary and secondary educational level, being older women, being from the richest household, and having a urine test during antenatal visits were significantly associated with the use of skilled delivery care. The value of intraclass correlation coefficient supported a significant community-level effect on the likelihood of using skilled delivery care. Conclusions. Factors operating both at the individual level and community level were found significantly associated with the use of skilled delivery care in Ethiopia. A considerable variation at community level accounts for the difference in the use of skilled delivery level.


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