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.

scholarly journals How interactions between animal movement and landscape processes modify local range dynamics and extinction risk

2014 ◽  
Vol 10 (5) ◽  
pp. 20140198 ◽  
Author(s):  
Damien A. Fordham ◽  
Kevin T. Shoemaker ◽  
Nathan H. Schumaker ◽  
H. Reşit Akçakaya ◽  
Nathan Clisby ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Landscape Structure ◽  
Animal Movement ◽  
Extinction Risk ◽  
Species Distributions ◽  
Turtle Species ◽  
Novel Approach ◽  
Range Dynamics ◽  
The Individual ◽  
Local Range

Forecasts of range dynamics now incorporate many of the mechanisms and interactions that drive species distributions. However, connectivity continues to be simulated using overly simple distance-based dispersal models with little consideration of how the individual behaviour of dispersing organisms interacts with landscape structure (functional connectivity). Here, we link an individual-based model to a niche-population model to test the implications of this omission. We apply this novel approach to a turtle species inhabiting wetlands which are patchily distributed across a tropical savannah, and whose persistence is threatened by two important synergistic drivers of global change: predation by invasive species and overexploitation. We show that projections of local range dynamics in this study system change substantially when functional connectivity is modelled explicitly. Accounting for functional connectivity in model simulations causes the estimate of extinction risk to increase, and predictions of range contraction to slow. We conclude that models of range dynamics that simulate functional connectivity can reduce an important source of bias in predictions of shifts in species distributions and abundances, especially for organisms whose dispersal behaviours are strongly affected by landscape structure.

scholarly journals Prioritizing conservation actions in urbanizing landscapes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
A. K. Ettinger ◽  
E. R. Buhle ◽  
B. E. Feist ◽  
E. Howe ◽  
J. A. Spromberg ◽  
...  
Keyword(s):  
Coho Salmon ◽  
Predictive Accuracy ◽  
Critical Threshold ◽  
Negative Effects ◽  
Conservation Action ◽  
Critical Thresholds ◽  
Species Response ◽  
Response Data ◽  
Conservation Actions ◽  
Preservation And Restoration

AbstractUrbanization-driven landscape changes are harmful to many species. Negative effects can be mitigated through habitat preservation and restoration, but it is often difficult to prioritize these conservation actions. This is due, in part, to the scarcity of species response data, which limit the predictive accuracy of modeling to estimate critical thresholds for biological decline and recovery. To address these challenges, we quantify effort required for restoration, in combination with a clear conservation objective and associated metric (e.g., habitat for focal organisms). We develop and apply this framework to coho salmon (Oncorhynchus kisutch), a highly migratory and culturally iconic species in western North America that is particularly sensitive to urbanization. We examine how uncertainty in biological parameters may alter locations prioritized for conservation action and compare this to the effect of shifting to a different conservation metric (e.g., a different focal salmon species). Our approach prioritized suburban areas (those with intermediate urbanization effects) for preservation and restoration action to benefit coho. We found that prioritization was most sensitive to the selected metric, rather than the level of uncertainty or critical threshold values. Our analyses highlight the importance of identifying metrics that are well-aligned with intended outcomes.

scholarly journals Species interactions in three Lemnaceae species growing along a gradient of zinc pollution

2021 ◽  
Author(s):  
Lorena Lanthemann ◽  
Sofia van Moorsel
Keyword(s):  
Growth Rates ◽  
Species Interactions ◽  
Metal Removal ◽  
Lemna Minor ◽  
Polluted Water ◽  
Future Research ◽  
Individual Species ◽  
High Tolerance ◽  
Species Mixture ◽  
The Individual

Duckweeds (Lemnaceae) are increasingly studied for their potential for phytoremediation of heavy-metal polluted water bodies. A prerequisite for metal removal, however, is the tolerance of the organism to the pollutant, e.g., the metal zinc (Zn). Duckweeds have been shown to differ in their tolerances to Zn, however, despite them most commonly co-occurring with other species, there is a lack of research concerning the effect of species interactions on Zn tolerance. Here we tested whether the presence of a second species influenced the growth rate of the three duckweed species Lemna minor, Lemna gibba, and Lemna turionifera. We used four different Zn concentrations in a replicated microcosm experiment under sterile conditions, either growing the species in isolation or in a 2-species mixture. The response to Zn differed between species, but all three species showed a high tolerance to Zn, with low levels of Zn even increasing the growth rates. The growth rates of the individual species were influenced by the identity of the competing species, but this was independent of the Zn concentration. Our results suggest that species interactions should be considered in future research with duckweeds and that several duckweed species have high tolerance to metal pollution, making them candidates for phytoremediation efforts.

Ecological Interactions and Macroevolution: A New Field with Old Roots

2020 ◽  
Vol 51 (1) ◽  
pp. 215-243 ◽  
Author(s):  
David H. Hembry ◽  
Marjorie G. Weber
Keyword(s):  
Species Interactions ◽  
Interspecific Interactions ◽  
Biotic Interactions ◽  
Evolutionary Change ◽  
Future Research ◽  
Ecological Interactions ◽  
Open Questions ◽  
Work Done ◽  
Lineage Diversification

Linking interspecific interactions (e.g., mutualism, competition, predation, parasitism) to macroevolution (evolutionary change on deep timescales) is a key goal in biology. The role of species interactions in shaping macroevolutionary trajectories has been studied for centuries and remains a cutting-edge topic of current research. However, despite its deep historical roots, classic and current approaches to this topic are highly diverse. Here, we combine historical and contemporary perspectives on the study of ecological interactions in macroevolution, synthesizing ideas across eras to build a zoomed-out picture of the big questions at the nexus of ecology and macroevolution. We discuss the trajectory of this important and challenging field, dividing research into work done before the 1970s, research between 1970 and 2005, and work done since 2005. We argue that in response to long-standing questions in paleobiology, evidence accumulated to date has demonstrated that biotic interactions (including mutualism) can influence lineage diversification and trait evolution over macroevolutionary timescales, and we outline major open questions for future research in the field.

scholarly journals Plant functional connectivity - integrating landscape structure and effective dispersal

2017 ◽  
Vol 105 (6) ◽  
pp. 1648-1656 ◽  
Author(s):  
Alistair G. Auffret ◽  
Yessica Rico ◽  
James M. Bullock ◽  
Danny A. P. Hooftman ◽  
Robin J. Pakeman ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Landscape Structure

scholarly journals Disease outbreak thresholds emerge from interactions between movement behavior, landscape structure, and epidemiology

2018 ◽  
Vol 115 (28) ◽  
pp. 7374-7379 ◽  
Author(s):  
Lauren A. White ◽  
James D. Forester ◽  
Meggan E. Craft
Keyword(s):  
Spatial Heterogeneity ◽  
Landscape Structure ◽  
Spatial Organization ◽  
Complex Disease ◽  
Animal Movement ◽  
Pathogen Transmission ◽  
Movement Behavior ◽  
Disease Dynamics ◽  
Conspecific Density ◽  
Pathogen Persistence

Disease models have provided conflicting evidence as to whether spatial heterogeneity promotes or impedes pathogen persistence. Moreover, there has been limited theoretical investigation into how animal movement behavior interacts with the spatial organization of resources (e.g., clustered, random, uniform) across a landscape to affect infectious disease dynamics. Importantly, spatial heterogeneity of resources can sometimes lead to nonlinear or counterintuitive outcomes depending on the host and pathogen system. There is a clear need to develop a general theoretical framework that could be used to create testable predictions for specific host–pathogen systems. Here, we develop an individual-based model integrated with movement ecology approaches to investigate how host movement behaviors interact with landscape heterogeneity (in the form of various levels of resource abundance and clustering) to affect pathogen dynamics. For most of the parameter space, our results support the counterintuitive idea that fragmentation promotes pathogen persistence, but this finding was largely dependent on perceptual range of the host, conspecific density, and recovery rate. For simulations with high conspecific density, slower recovery rates, and larger perceptual ranges, more complex disease dynamics emerged, and the most fragmented landscapes were not necessarily the most conducive to outbreaks or pathogen persistence. These results point to the importance of interactions between landscape structure, individual movement behavior, and pathogen transmission for predicting and understanding disease dynamics.

Deforestation dynamics in a fragmented region of southern Amazonia: evaluation and future scenarios

2008 ◽  
Vol 35 (2) ◽  
pp. 93-103 ◽  
Author(s):  
FERNANDA MICHALSKI ◽  
CARLOS A. PERES ◽  
IAIN R. LAKE
Keyword(s):  
Land Use ◽  
Land Use Planning ◽  
Landscape Structure ◽  
Forest Cover ◽  
Environmental Law ◽  
Critical Threshold ◽  
Future Scenarios ◽  
Forest Patches ◽  
Deforestation Rate ◽  
Southern Amazonia

SUMMARYThe ‘arc of deforestation’ of southern Amazonia has one of the highest deforestation rates documented anywhere in the world. Landscape changes in a poorly studied but strategically important region in the Brazilian Amazon were studied using biennial Landsat TM/ETM+ images from 1984 to 2004. Deforestation rate for the period 1984–2004 was 2.47% yr−1 in the 7295 km2 study area, but decreased to 1.99% and 2.15% in 2000–2002 and 2002–2004, respectively. Landscape structure changes were characterized by smaller forest patches that were further apart, but increasingly complex in shape. Deforestation was mainly driven by cattle ranching, which in turn was affected by distance to roads, with forest cover increasing at greater distances from roads. A multi-layer perceptron was used to develop future scenarios based on Markov Chain analysis. Based on current land use, forest cover in the region will decline from 42% in 2004 to 21% by 2016. Results indicate a critical threshold at 51% of forest cover in which landscape structure and connectivity changes abruptly. This suggests that the region requires greater efforts in environmental law enforcement, land-use planning and education programmes to maintain the remaining forest cover near this threshold.

Tracking livestock using global positioning systems - are we still lost?

2011 ◽  
Vol 51 (3) ◽  
pp. 167 ◽  
Author(s):  
D. L. Swain ◽  
M. A. Friend ◽  
G. J. Bishop-Hurley ◽  
R. N. Handcock ◽  
T. Wark
Keyword(s):  
Experimental Design ◽  
Statistical Power ◽  
Animal Movement ◽  
Experimental Unit ◽  
Future Research ◽  
Gps Data ◽  
Global Positioning Systems ◽  
Positioning Systems ◽  
Global Positioning ◽  
Free Grazing

Since the late 1980s, satellite-based global positioning systems (GPS) have provided unique and novel data that have been used to track animal movement. Tracking animals with GPS can provide useful information, but the cost of the technology often limits experimental replication. Limitations on the number of devices available to monitor the behaviour of animals, in combination with technical constraints, can weaken the statistical power of experiments and create significant experimental design challenges. The present paper provides a review and synthesis of using GPS for livestock-based studies and suggests some future research directions. Wildlife ecologists working in extensive landscapes have pioneered the use of GPS-based devices for tracking animals. Wildlife researchers have focussed efforts on quantifying and addressing issues associated with technology limitations, including spatial accuracy, rate of data collection, battery life and environmental factors causing loss of data. It is therefore not surprising that there has been a significant number of methodological papers published in the literature that have considered technical developments of GPS-based animal tracking. Livestock scientists have used GPS data to inform them about behavioural differences in free-grazing experiments. With a shift in focus from the environment to the animal comes the challenge of ensuring independence of the experimental unit. Social facilitation challenges independence of the individual in a group. The use of spatial modelling methods to process GPS data provides an opportunity to determine the degree of independence of data collected from an individual animal within behavioural-based studies. By using location and movement information derived from GPS data, researchers have been able to determine the environmental impact of grazing animals as well as assessing animal responses to management activities or environmental perturbations. Combining satellite-derived remote-sensing data with GPS-derived landscape preference indices provides a further opportunity to identify landscape avoidance and selection behaviours. As spatial livestock monitoring tools become more widely used, there will be a greater need to ensure the data and associated processing methods are able to answer a broader range of questions. Experimental design and analytical techniques need to be given more attention if GPS technology is to provide answers to questions associated with free-grazing animals.

Comparative Primate Connectomics

2018 ◽  
Vol 91 (3) ◽  
pp. 170-179 ◽  
Author(s):  
James K. Rilling ◽  
Martijn P. van den Heuvel
Keyword(s):  
White Matter ◽  
Functional Connectivity ◽  
Tool Use ◽  
False Negative ◽  
Structural Connectivity ◽  
Cell Counting ◽  
Primate Species ◽  
Future Research ◽  
Ecological Niches ◽  
Human Specific

A connectome is a comprehensive map of neural connections of a species nervous system. While recent work has begun comparing connectomes across a wide breadth of species, we present here a more detailed and specific comparison of connectomes across the primate order. Long-range connections are thought to improve communication efficiency and thus brain function but are costly in terms of energy and space utilization. Methods for measuring connectivity in the brain include measuring white matter volume, histological cell counting, anatomical tract tracing, diffusion-weighted imaging and tractography, and functional connectivity in MRI. Comparisons of global white matter connectivity suggest that larger primate brains are less well connected than smaller primate brains, but that humans have more connections than expected for our cortical neuron number, which may be concentrated in the prefrontal cortex. Although there is significant overlap in structural connectivity between humans and nonhuman primates, human-specific connections are found in cortical areas involved with language, imitation, and tool use. Similar to structural connectivity, there is also widespread overlap between humans and macaques in resting state functional connectivity. However, there are again a number of human-specific connections in cortical regions involved in language, tool use, and empathy. Comparative connectomics also offers the opportunity to detect specializations of connectivity in other primate species besides humans. Future research should capitalize on the ability of diffusion tractography to measure connectivity in postmortem brains that could expand the representation of species beyond humans, chimpanzees, and rhesus macaques, and facilitate identification of connectivity-based adaptations to different social and ecological niches. This work will require careful attention to establishing cortical homologies across species and to improving tractography methods to limit detection of false-positive and false-negative connections. Finally, it will be important to attempt to establish the functional significance of variation in connectivity profiles by examining how these covary with behavior and cognition both across and within species.

Sign in / Sign up

Export Citation Format

Share Document