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1. A framework for modern time geography: emphasizing diverse constraints on accessibility

   https://doi.org/10.1007/s10109-023-00404-1  

   Dodge, Somayeh; Nelson, Trisalyn A. (February 2023, Journal of Geographical Systems)

   Time geography is widely used by geographers as a model for understanding accessibility. Recent changes in how access is created, an increasing awareness of the need to better understand individual variability in access, and growing availability of detailed spatial and mobility data have created an opportunity to build more flexible time geography models. Our goal is to outline a research agenda for a modern time geography that allows new modes of access and a variety of data to flexibly represent the complexity of the relationship between time and access. A modern time geography is more able to nuance individual experience and creates a pathway for monitoring progress toward inclusion. We lean on the original work by Hägerstrand and the field of movement GIScience to develop both a framework and research roadmap that, if addressed, can enhance the flexibility of time geography to help ensure time geography will continue as a cornerstone of accessibility research. The proposed framework emphasizes the individual and differentiates access based on how individuals experience internal , external , and structural factors. To enhance nuanced representation of inclusion and exclusion, we propose research needs, focusing efforts on implementing flexible space–time constraints, inclusion of definitive variables, addressing mechanisms for representing and including relative variables, and addressing the need to link between individual and population scales of analysis. The accelerated digitalization of society, including availability of new forms of digital spatial data, combined with a focus on understanding how access varies across race, income, sexual identity, and physical limitations requires new consideration for how we include constraints in our studies of access. It is an exciting era for time geography and there are massive opportunities for all geographers to consider how to incorporate new realities and research priorities into time geography models, which have had a long tradition of supporting theory and implementation of accessibility research. 

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2. Ecological niche modeling of Australian Loranthaceae mistletoes using a novel haustorial perspective

   Trang, Kenneth; Wilson, Carol A. (July 2021, Botany 2021)

   Mistletoe spatial patterns are poorly understood on a macroecological scale. Previous research conducted at the family-level on Loranthaceae from Australia demonstrated that unlike most plants, mistletoe species richness patterns do not correlate significantly with water and energy input. However, field studies suggested a relationship between the structure of the host-parasite union (haustorium) and environment. We hypothesize that haustorial type influences relationships between the abiotic environment and mistletoe spatial patterns. To investigate this hypothesis, we constructed ecological niche models for individual haustorial types. We have previously compared the distributions of haustorial types in both geographic and environmental space using geographic mapping and PCA, respectively. Here, we expand on our study by examining species richness, constructing predictive models, and emphasizing habitat types. Using the haustorial specimen collection housed at the UC Herbarium and relevant literature, we identified the haustorial type of 55 of the 73 Australia Loranthaceae mistletoe species. Using geographic distributional data from the Atlas of Living Australia and environmental data from WorldClim, we plotted haustorial groups in both geographic and environmental space, compared clusters in principle component space, and calculated Hutchinsonian niche overlap. We used regression to analyze the relationship between species richness and environmental variables at the haustorial level. Lastly, we constructed maximum entropy models to estimate the probability of occurrence of each haustorial group, analyzing the relative contributions of each variable to each model. We discovered that haustorial type is relatively conserved among the Australian Loranthaceae mistletoe genera, with seven out of nine genera exhibiting one haustorial type. Species with epicortical roots (ER), the ancestral character, are exclusively associated with coastal regions while those with derived haustorial types occur across the continent, including desert regions. Environmental analyses confirmed that species with ER are found in regions with milder temperatures and higher precipitation than derived types. Species richness patterns of some haustorial types, including ER, are significantly correlated with most environmental variables, while derived haustorial types are not. Maxent models for species with ER haustoria predict the highest probability of occurrence for coastal regions, while models constructed for derived types feature less bias for coastal regions. Our models demonstrate that relationships between the abiotic environment and mistletoe spatial patterns depend in part on the haustorial type. Hypotheses proposed to explain relationships between abiotic constraint on distribution and haustorial type include differences in water uptake efficiency, exposure of haustoria to the environment, longevity of haustoria, and host preference of species. 

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3. Areal Analysis of Language Attitudes and Practices: A Case Study from Nepal

   Hildebrandt, Kristine A.; Hu, Shunfu (January 2017, Language documentation and conservation)

   This paper has two aims. One aim is to consider non-structural (language attitude and use) variables as valid in the field of dialect and linguistic geography in an inner Himalayan valley of Nepal, where four languages have traditionally co- existed asymmetrically and which demonstrate different degrees of vitality vs. endangerment. The other aim is an application of modified spatiality as it aligns with speaker attitudes and practices amidst recent and ongoing socio-economic and population changes. We demonstrate that variation in self-reported attitudes and practices across languages in this region can be explained as much with adjusted spatial factors (labeled ‘social space’) as with traditional social factors (e.g. gender, age, formal education, occupation, etc.). As such, our study contributes to a dis- course on the role and potential of spatiality in sociolinguistic analyses of smaller language communities. 

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4. Inverse Distance Weighted Random Forests: Modeling Unevenly Distributed Non-Stationary Geographic Data

   https://doi.org/10.1109/ICACSIS51025.2020.9263208  

   Deng, Liangdong; Adjouadi, Malek; Rishe, Naphtali (October 2020, 2020 International Conference on Advanced Computer Science and Information Systems (ICACSIS))

   null (Ed.)

   Recent years saw explosive growth of Human Geography Data, in which spatial non-stationarity is often observed, i.e., relationships between features depend on the location. For these datasets, a single global model cannot accurately describe the relationships among features that vary across space. To address this problem, a viable solution- that has been adopted by many studies-is to create multiple local models instead of a global one, with each local model representing a subregion of the space. However, the challenge with this approach is that the local models are only fitted to nearby observations. For sparsely sampled regions, the data could be too few to generate any high-quality model. This is especially true for Human Geography datasets, as human activities tend to cluster at a few locations. In this paper, we present a modeling method that addresses this problem by letting local models operate within relatively large subregions, where overlapping is allowed. Results from all local models are then fused using an inverse distance weighted approach, to minimize the impact brought by overlapping. Experiments showed that this method handles non-stationary geographic data very Well, even When they are unevenly distributed. 

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5. Spatiotemporal dynamics of genetic variation at the quantitative and molecular levels within a natural Arabidopsis thaliana population

   https://doi.org/10.1111/1365-2745.13981  

   Méndez‐Vigo, Belén; Castilla, Antonio R.; Gómez, Rocío; Marcer, Arnald; Alonso‐Blanco, Carlos; Picó, F. Xavier (November 2022, Journal of Ecology)

   Abstract Evolutionary change begins at the population scale. Therefore, understanding adaptive variation requires the identification of the factors maintaining and shaping standing genetic variation at the within‐population level. Spatial and temporal environmental heterogeneity represent ecological drivers of within‐population genetic variation, determining the evolutionary trajectory of populations along with random processes. Here, we focused on the effects of spatiotemporal heterogeneity on quantitative and molecular variation in a natural population of the annual plant Arabidopsis thaliana . We sampled 1093 individuals from a Spanish A. thaliana population across an area of 7.4 ha for 10 years (2012–2021). Based on a sample of 279 maternal lines, we estimated spatiotemporal variation in life‐history traits and fitness from a common garden experiment. We genotyped 884 individuals with nuclear microsatellites to estimate spatiotemporal variation in genetic diversity. We assessed spatial patterns by estimating spatial autocorrelation of traits and fine‐scale genetic structure. We analysed the relationships between phenotypic variation, geographical location and genetic relatedness, as well as the effects of environmental suitability and genetic rarity on phenotypic variation. The common garden experiment indicated that there was more temporal than spatial variation in life‐history traits and fitness. Despite the differences among years, genetic distance in ecologically relevant traits (e.g. flowering time) tended to be positively correlated to genetic distance among maternal lines, while isolation by distance was less important. Genetic diversity exhibited significant spatial structure at short distances, which were consistent among years. Finally, genetic rarity, and not environmental suitability, accounted for genetic variation in life‐history traits. Synthesis . Our study highlighted the importance of repeated sampling to detect the large amount of genetic diversity at the quantitative and molecular levels that a single A. thaliana population can harbour. Overall, population genetic attributes estimated from our long‐term monitoring scheme (genetic relatedness and genetic rarity), rather than biological (dispersal) or ecological (vegetation types and environmental suitability) factors, emerged as the most important drivers of within‐population structure of phenotypic variation in A. thaliana . 

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