scholarly journals Dispersers’ habitat detection and settling abilities modulate the effect of habitat amount on metapopulation resilience

2021 ◽  
Author(s):  
Louise Riotte-Lambert ◽  
Fabien Laroche
Keyword(s):  
Animal Movement ◽  
Habitat Amount ◽  
Fragmented Landscapes ◽  
Habitat Patches ◽  
Shadow Effect ◽  
Metapopulation Theory ◽  
Metapopulation Models ◽  
Mechanistic Understanding ◽  
The Relationship

Abstract Context Metapopulation theory makes useful predictions for conservation in fragmented landscapes. For randomly distributed habitat patches, it predicts that the ability of a metapopulation to recover from low occupancy level (the “metapopulation capacity”) linearly increases with habitat amount. This prediction derives from describing the dispersal between two patches as a function of their features and the distance separating them only, without interaction with the rest of the landscape. However, if individuals can stop dispersal when hitting a patch (“habitat detection and settling” ability), the rest of habitat may modulate the dispersal between two patches by intercepting dispersers (which constitutes a “shadow” effect). Objectives We aim at evaluating how habitat detection and settling ability, and the subsequent shadow effect, can modulate the relationship between the metapopulation capacity and the habitat amount in the metapopulation. Methods Considering two simple metapopulation models with contrasted animal movement types, we used analytical predictions and simulations to study the relationship between habitat amount and metapopulation capacity under various levels of dispersers’ habitat detection and settling ability. Results Increasing habitat detection and settling ability led to: (i) larger metapopulation capacity values than expected from classic metapopulation theory and (ii) concave habitat amount–metapopulation capacity relationship. Conclusions Overlooking dispersers’ habitat detection and settling ability may lead to underestimating the metapopulation capacity and misevaluating the conservation benefit of increasing habitat amount. Therefore, a further integration of our mechanistic understanding of animals’ displacement into metapopulation theory is urgently needed.

scholarly journals How to find a metapopulationThis review is one of a series dealing with some aspects of the impact of habitat fragmentation on animals and plants. This series is one of several virtual symposia focussing on ecological topics that will be published in the Journal from time to time.

2007 ◽  
Vol 85 (10) ◽  
pp. 1031-1048 ◽  
Author(s):  
D.A. Driscoll
Keyword(s):  
Native Species ◽  
Field Data ◽  
Spatial Dynamics ◽  
Metapopulation Dynamics ◽  
Data Sets ◽  
Fragmented Landscapes ◽  
Metapopulation Theory ◽  
Metapopulation Models ◽  
The Impact ◽  
Analytical Approaches

Where habitat loss and fragmentation is severe, many native species are likely to have reduced levels of dispersal between remnant populations. For those species to avoid regional extinction in fragmented landscapes, they must undergo some kind of metapopulation dynamics so that local extinctions are countered by recolonisation. The importance of spatial dynamics for regional survival means that research into metapopulation dynamics is essential. In this review I explore the approaches taken to examine metapopulation dynamics, highlight the analytical methods used to get the most information out of field data, and discover some of the major research gaps. Statistical models, including Hanski’s incidence function model (IFM) are frequently applied to presence–absence data, an approach that is often strengthened using long-term data sets that document extinctions and colonisations. Recent developments are making the IFM more biologically realistic and expanding the range of situations for which the model is relevant. Although accurate predictions using the IFM seem unlikely, it may be useful for ranking management decisions. A key weakness of presence–absence modelling is that the mechanisms underlying spatial dynamics remain inferential, so combining modelling approaches with detailed demographic research is warranted. For species where very large data sets cannot be obtained to facilitate statistical modelling, a demographic approach alone or with stochastic modelling may be the only viable research angle to take. Dispersal is a central process in metapopulation dynamics. Research combining mark–recapture or telemetry methods with model-selection procedures demonstrate that dispersal is frequently oversimplified in conceptual and statistical metapopulation models. Dispersal models like the island model that underlies classic metapopulation theory do not approximate the behaviour of real species in fragmented landscapes. Nevertheless, it remains uncertain if additional biological realism will improve predictions of statistical metapopulation models. Genetic methods can give better estimates of dispersal than direct methods and take less effort, so they should be routinely explored alongside direct ecological methods. Recent development of metacommunity theory (communities connected by dispersal) emphasises a range of mechanisms that complement metapopulation theory. Taking both theories into account will enhance interpretation of field data. The extent of metapopulation dynamics in human modified landscapes remains uncertain, but we have a powerful array of field and analytical approaches for reducing this knowledge gap. The most informative way forward requires that many species are studied in the same fragmented landscape by applying a selection of approaches that reveal complementary aspects of spatial dynamics.

Site reoccupation in fragmented landscapes: testing predictions of metapopulation theory

2001 ◽  
Vol 70 (2) ◽  
pp. 182-190 ◽  
Author(s):  
Ralph S. Hames ◽  
Kenneth V. Rosenberg ◽  
James D. Lowe ◽  
Andre A. Dhondt
Keyword(s):  
Fragmented Landscapes ◽  
Metapopulation Theory

,In den Zeiten, wo das Wünschen noch geholfen hat’

2002 ◽  
Vol 24 (2) ◽  
Author(s):  
Ralf Stoecker
Keyword(s):  
Action Theory ◽  
Special Kind ◽  
Donald Davidson ◽  
Ontological Status ◽  
Standard Account ◽  
Mechanistic Understanding ◽  
Intentional Attitudes ◽  
The Relationship ◽  
As If ◽  
Psychological Concepts

AbstractThere is a widely accepted view in action theory (most prominently defended by Donald Davidson) according to which (1) actions are events, (2) reasons are intentional attitudes of the agent (pairs of beliefs and desires), and (3) acting for a reason entails that the reason rationalizes as well as causes the action. In the first part of my contribution I list seventeen difficulties for this standard account; in the second part I give an outline of how a more plausible conception of reasons and actions could look like. According to this conception, which is based on Gilbert Ryle’s criticism of a mechanistic understanding of psychological concepts, agency is due to a special kind of disposition of the agent, namely the disposition to behave as if the agent were permanently deliberating about what to do. The conception has surprising consequences for the ontological status of intentional attitudes and actions and for the relationship between action and responsibility.

scholarly journals Critical threshold effects of benthiscape structure on stream herbivore movement

2007 ◽  
Vol 362 (1479) ◽  
pp. 461-472 ◽  
Author(s):  
Julian D Olden
Keyword(s):  
Functional Connectivity ◽  
Current Velocity ◽  
Landscape Structure ◽  
Species Interactions ◽  
Animal Movement ◽  
Critical Threshold ◽  
Future Research ◽  
Threshold Effects ◽  
Habitat Patches ◽  
Critical Thresholds

Abstract In landscape ecology, substantial theoretical progress has been made in understanding how critical threshold levels of habitat loss may result in sudden changes in landscape connectivity to animal movement. Empirical evidence for such thresholds in real systems, however, remains scarce. Streambed landscapes provide a strong testing ground for studying critical thresholds because organisms are faced with substantial environmental heterogeneity while attempting to overcome the physical force of water. In this study, I report on the results from a series of experiments investigating the influence of habitat abundance and current velocity on the movement dynamics of two stream herbivores (caddisfly larva Agapetus boulderensis and snail Physa sp.) that differ substantially in how they perceive landscape structure. Specifically, I ask whether critical thresholds to herbivore movement exist in streambed landscapes. By exploiting the pattern recognition capabilities of artificial neural networks, I found that the rate, sinuosity and directionality of movement by Agapetus and Physa varied nonlinearly according to the abundance of habitat patches, current velocity and habitat–current interaction. Both the study organisms exhibited threshold responses to habitat abundance, yet the location and slope of these thresholds differed between species and with respect to different current velocities. These results suggest that a critical threshold in functional connectivity (i.e. the connection of habitat patches by dispersal) is not an inherent property of the landscape, but in fact emerges from the interplay of species' interactions with landscape structure. Moreover, current velocity interacted with habitat abundance to elicit strong upstream-oriented movement for both the species. This suggests that dispersing individuals may be polarized in the upstream direction and therefore functional connectivity is not equal in all directions. Such results highlight the need for future research addressing the sources of variability of critical threshold effects in ecological phenomena.

Sign in / Sign up

Export Citation Format

Share Document