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Urbanization is altering landscapes globally at an unprecedented rate. While ecological differences between urban and rural environments often promote phenotypic divergence among populations, it is unclear to what degree these trait differences arise from genetic divergence as opposed to phenotypic plasticity. Furthermore, little is known about how specific landscape elements, such as green corridors, impact genetic divergence in urban environments. We tested the hypotheses that: (1) urbanization, and (2) proximity to an urban green corridor influence genetic divergence in common milkweed (Asclepias syriaca) populations for phenotypic traits. Using seeds from 52 populations along three urban-to-rural subtransects in the Greater Toronto Area, Canada, one of which followed a green corridor, we grew ~ 1000 plants in a common garden setup and measured > 20 ecologically-important traits associated with plant defense/damage, reproduction, and growth over four years. We found significant heritable variation for nine traits within common milkweed populations and weak phenotypic divergence among populations. However, neither urbanization nor an urban green corridor influenced genetic divergence in individual traits or multivariate phenotype. These findings contrast with the expanding literature demonstrating that urbanization promotes rapid evolutionary change and offer preliminary insights into the eco-evolutionary role of green corridors in urban environments. [ABSTRACT FROM AUTHOR]

Urbanization exerts many pressures on species, yet little is known about how these pressures impact species interactions. Studies of urban plant-pollinator systems provide mounting evidence that urbanization impairs pollinator movement in fragmented urban landscapes, yet the consequences for pollinator-mediated plant reproduction remains unclear. In non-urban areas, habitat corridors can facilitate the movement of organisms including pollinators, but whether these corridors facilitate plant-pollinator interactions in urban areas remains understudied. To examine how urban environments and a green corridor influence plant-pollinator interactions, we measured reproductive success in the native plant common milkweed (Asclepias syriaca), and the community structure of its pollinators, for two years along two urban–rural transects in the Greater Toronto Area, Canada, one of which followed a green corridor. We found that urbanization decreased male fitness (i.e., pollen removal), increased fruit set (i.e., mean no. of follicles per inflorescence), and inconsistently affected female fitness (i.e., no. of follicles) in A. syriaca. Urbanization simultaneously decreased pollinator abundance but increased pollinator richness. Proximity to a green corridor inconsistently affected male fitness but increased reproductive effort (i.e., no. of inflorescences) in A. syriaca, while pollinator diversity and richness was lower in the corridor. Notably, there were no consistent relationships between pollinator community structure and reproductive success in A. syriaca in both the presence, and absence, of a green corridor. These results demonstrate the complexity with which urbanization, a green corridor, and pollinator communities can shape the reproductive investment and fitness of native plant populations. [ABSTRACT FROM AUTHOR]

Sustainable land-use planning should consider large-scale landscape connectivity. Commonly-used species-specific connectivity models are difficult to generalize for a wide range of taxa. In the context of multi-functional land-use planning, there is growing interest in species-agnostic approaches, modelling connectivity as a function of human landscape modification. We propose a conceptual framework, apply it to model connectivity as current density across Alberta, Canada, and assess map sensitivity to modelling decisions. We directly compared the uncertainty related to (1) the definition of the degree of human modification, (2) the decision whether water bodies are considered barriers to movement, and (3) the scaling function used to translate degree of human modification into resistance values. Connectivity maps were most sensitive to the consideration of water as barrier to movement, followed by the choice of scaling function, whereas maps were more robust to different conceptualizations of the degree of human modification. We observed higher concordance among cells with high (standardized) current density values than among cells with low values, which supports the identification of cells contributing to larger-scale connectivity based on a cut-off value. We conclude that every parameter in species-agnostic connectivity modelling requires attention, not only the definition of often-criticized expert-based degrees of human modification. [ABSTRACT FROM AUTHOR]

Landscape genetics is an emerging interdisciplinary field that combines methods and concepts from population genetics, landscape ecology, and spatial statistics. The interest in landscape genetics is steadily increasing, and the field is evolving rapidly. We here outline four major challenges for future landscape genetic research that were identified during an international landscape genetics workshop. These challenges include (1) the identification of appropriate spatial and temporal scales; (2) current analytical limitations; (3) the expansion of the current focus in landscape genetics; and (4) interdisciplinary communication and education. Addressing these research challenges will greatly improve landscape genetic applications, and positively contribute to the future growth of this promising field. [ABSTRACT FROM AUTHOR]

The article focuses on the definition of landscape genetics as a combination of landscape ecology and population genetics. The landscape genetics aims to provide information about the interaction between landscape features and microevolutionary processes such as gene flow, genetic drift and selection of two ecological and evolutionary processes. Thus, the definition of landscape genetics is clearer on the population genetic than on the landscape ecological side and spatial scale. The landscape genetics is an important emerging research topic that integrates landscape pattern with population genetics.

The process of recolonization after disturbance is crucial for the persistence and dynamics of patch-tracking metapopulations. We developed a model to compare the spatial distribution and spatial genetic structure of the epiphytic lichen Lobaria pulmonaria within the perimeter of two reconstructed 19th century disturbances with a nearby reference area without stand-level disturbance. Population genetic data suggested that after stand-replacing disturbance, each plot was colonized by one or a few genotypes only, which subsequently spread clonally within a local neighborhood. The model (cellular automaton) aimed at testing the validity of this interpretation and at assessing the relative importance of local dispersal of clonal propagules vs. long-distance dispersal of clonal and/or sexual diaspores. A reasonable model fit was reached for the empirical data on host tree distribution, lichen distribution, and tree- and plot-level genotype diversity of the lichen in the reference area. Although model calibration suggested a predominance of local dispersal of clonal propagules, a substantial contribution of immigration of non-local genotypes by long-distance dispersal was needed to reach the observed levels of genotype diversity. The model could not fully explain the high degree of clonality after stand-replacing disturbance, suggesting that the dispersal process itself may not be stationary but depend on the ecological conditions related to disturbance. [ABSTRACT FROM AUTHOR]

Management-oriented models of cattle habitat use often treat grazing pressure as a single variable summarizing all cattle activities. This paper addresses the following questions: How does the spatial pattern of cattle effects vary between cattle activities in a highly heterogeneous landscape? Do these patterns change over the grazing season as forage availability decreases? What are the respective roles of natural and management-introduced structures? We estimated the intensity of herbage removal, dung deposition and trampling after each of three grazing periods on a grid of 25 m × 25 m cells covering an entire paddock in the Swiss Jura Mountains. We found no significant positive correlations between cattle effects. Spatial patterns weakened through the season for grazing and trampling, whereas dunging patterns changed little between grazing periods. Redundancy analysis showed that different cattle effects were correlated with different environmental variables and that the importance of management-introduced variables was highest for herbage removal. Autocorrelograms and partial redundancy analyses using principal coordinates of neighbour matrices suggested that dunging patterns were more coarse-grained than the others. Systematic differences in the spatial and seasonal patterns of cattle effects may result in complex interactions with vegetation involving feedback effects through nutrient shift, with strong implications for ecosystem management. In heterogeneous environments, such as pasture-woodland landscapes, spatially explicit models of vegetation dynamics need to model cattle effects separately. [ABSTRACT FROM AUTHOR]

Focuses on the quantification of habitat specificity to assess the contribution of a patch to species richness at a landscape scale. Factors on which the potential value of an area for biodiversity conservation depends; Contribution of several types of land use to the overall species richness; Approach used to provide a solution to the problem of scaling species richness.

Examines the effects of habitat variability and habitat heterogeneity based on the partitioning of landscape species diversity into additive components. Components of within- and between-community diversity at four scale levels for three diversity measures of species richness, Shannon index, and Simpson diversity; Role of landscape composition, in explaining landscape species richness.