Predicting Landscape-Genetic Consequences of Habitat Loss, Fragmentation and Mobility for Multiple Species of Woodland Birds

Inference concerning the impact of habitat fragmentation on dispersal and gene flow is a key theme in landscape genetics. Recently, the ability of established approaches to identify reliably the differential effects of landscape structure (e.g. land-cover composition, remnant vegetation configuration and extent) on the mobility of organisms has been questioned. More explicit methods of predicting and testing for such effects must move beyond post hoc explanations for single landscapes and species. Here, we document a process for making a priori predictions, using existing spatial and ecological data and expert opinion, of the effects of landscape structure on genetic structure of multiple species across replicated landscape blocks. We compare the results of two common methods for estimating the influence of landscape structure on effective distance: least-cost path analysis and isolation-by-resistance. We present a series of alternative models of genetic connectivity in the study area, represented by different landscape resistance surfaces for calculating effective distance, and identify appropriate null models. The process is applied to ten species of sympatric woodland-dependant birds. For each species, we rank a priori the expectation of fit of genetic response to the models according to the expected response of birds to loss of structural connectivity and landscape-scale tree-cover. These rankings (our hypotheses) are presented for testing with empirical genetic data in a subsequent contribution. We propose that this replicated landscape, multi-species approach offers a robust method for identifying the likely effects of landscape fragmentation on dispersal

Monitoring ecological consequences of efforts to restore landscape-scale connectivity

© 2017 Elsevier LtdManaging and restoring connectivity that enables wildlife movement through landscapes is the primary approach to reduce harmful effects of habitat loss and fragmentation. Improved connectivity is also increasingly invoked as a strategy to mitigate negative impacts of climate change by enabling species to track preferred environments and maintain evolutionary processes. Although initiatives to improve connectivity using restoration are becoming commonplace, we do not know how successful these actions are, nor which mechanisms underlie biotic responses. Most ecological monitoring focuses on site condition or quality rather than those landscape-scale processes that connectivity is intended to facilitate. To assess biodiversity responses to connectivity initiatives, we argue that new monitoring approaches are needed that distinguish the roles of connectivity restoration from those of habitat augmentation or improvement. To address this critical gap, we developed a conceptual model of the hypothesised roles of connectivity in complex landscapes and a linked framework to guide design of connectivity monitoring approaches in an adaptive management context. We demonstrate that integrated monitoring approaches using complementary methods are essential to reveal whether long-term landscape-scale goals are being achieved, and to determine whether connectivity management and restoration are the mechanisms responsible. We summarize a real-world example of applying our approach to assist government develop a monitoring plan for a large-scale connectivity conservation initiative in the Australian Capital Territory. As well as highlighting the utility of the framework to help managers make informed choices about monitoring, this example illustrates the difficulties of convincing funding bodies to include monitoring in project budgets and the questions more likely to be answered with limited funds. Synthesis and applications. Implementing an effective strategy to monitor connectivity conservation initiatives necessarily involves more work but we argue it is an essential investment rather than an additional cost. By optimizing allocation of limited monitoring resources, we can more effectively implement management that improves functional connectivity, and understand how changing connectivity affects population persistence

Animal movement in dynamic landscapes : interaction between behavioural strategies and resource distributions

Most ecological and evolutionary processes are thought to critically depend on dispersal and individual movement but there is little empirical information on the movement strategies used by animals to find resources. In particular, it is unclear whether behavioural variation exists at all scales, or whether behavioural decisions are primarily made at small spatial scales and thus broad-scale patterns of movement simply reflect underlying resource distributions. We evaluated animal movement responses to variable resource distributions using the grey teal (Anas gracilis) in agricultural and desert landscapes in Australia as a model system. Birds in the two landscapes differed in the fractal dimension of their movement paths, with teal in the desert landscape moving less tortuously overall than their counterparts in the agricultural landscape. However, the most striking result was the high levels of individual variability in movement strategies, with different animals exhibiting different responses to the same resources. Teal in the agricultural basin moved with both high and low tortuosity, while teal in the desert basin primarily moved using low levels of tortuosity. These results call into question the idea that broad-scale movement patterns simply reflect underlying resource distributions, and suggest that movement responses in some animals may be behaviourally complex regardless of the spatial scale over which movement occurs

Interpreting realized pollen flow in terms of pollinator travel paths and land-use resistance in heterogeneous landscapes

Widespread ecosystem change has led to declines in species world-wide. The loss of pollinators in particular constitutes a problem for ecosystem function and crop production. Understanding how landscape change affects pollinator movement, effective pollen flow, and plant and pollinator survival is therefore a global priority. In this study we investigated patterns of effective pollen flow, using wild cherry tree (Prunus avium) progeny arrays, to address two questions in three case studies: Do land-use types present different resistances to pollinator movement? Which pollinator travel path best explains the pollination data (straight lines, weighted straight lines, least cost paths or pair-wise resistance)? Trees and progeny arrays were genotyped and effective pollen flow and pollinator movement were estimated using the spatially explicit mating model. We found that pollinators did modify their travel paths in response to land-use type and arrangement, but the travel path that best described pollinator movement and the resistance rank of the land uses depended on the type and size of land-use patches and the landscape context. We propose a novel theoretical framework rooted in behavioural ecology, the resource model, for interpreting pollinator behaviour in heterogeneous landscapes. We conclude by discussing the importance and practicality of conservation and management strategies in which native and non-native land-use types together provide functional habitat and support ecosystem services across economic landscapes

Making decisions to conserve species under climate change

Severe impacts on biodiversity are predicted to arise from climate change. These impacts may not be adequately addressed by conventional approaches to conservation. As a result, additional management actions are now being considered. However, there is currently limited guidance to help decision makers choose which set of actions (and in what order) is most appropriate for species that are considered to be vulnerable. Here, we provide a decision framework for the full complement of actions aimed at conserving species under climate change from ongoing conservation in existing refugia through various forms of mobility enhancement to ex situ conservation outside the natural environment. We explicitly recognize that allocation of conservation resources toward particular actions may be governed by factors such as the likelihood of success, cost and likely co-benefits to non-target species in addition to perceived vulnerability of individual species. As such, we use expert judgment of probable tradeoffs in resource allocation to inform the sequential evaluation of proposed management interventions