Linking movement behaviour, dispersal and population processes: is individual variation a key?

Abstract

Summary 1.Movement behaviour has become increasingly important in dispersal ecology and dispersal is central to the development of spatially explicit population ecology. The ways in which the elements have been brought together are reviewed with particular emphasis on dispersal distance distributions and the value of mechanistic models. 2.There is a continuous range of movement behaviours and in some species, dispersal is a clearly delineated event but not in others. The biological complexities restrict conclusions to high-level generalizations but there may be principles that are common to dispersal and other movements. 3. Random walk and diffusion models when appropriately elaborated can provide an understanding of dispersal distance relationships on spatial and temporal scales relevant to dispersal. Leptokurtosis in the relationships may be the result of a combination of factors including population heterogeneity, correlation, landscape features, time integration and density dependence. The inclusion in diffusion models of individual variation appears to be a useful elaboration. The limitations of the negative exponential and other phenomenological models are discussed. 4. The dynamics of metapopulation models are sensitive to what appears to be small differences in the assumptions about dispersal. In order to represent dispersal realistically in population models, it is suggested that phenomenological models should be replaced by those based on movement behaviour incorporating individual variation. 5. The conclusions are presented as a set of candidate principles for evaluation. The main features of the principles are that uncorrelated or correlated random walk, not linear movement, is expected where the directions of habitat patches are unpredictable and more complex behaviour when organisms have the ability to orientate or navigate. Individuals within populations vary in their movement behaviour and dispersal; part of this variation is a product of random elements in movement behaviour and some of it is heritable. Local and metapopulation dynamics are influenced by population heterogeneity in dispersal characteristics and heritable changes in dispersal propensity occur on time-scales short enough to impact population dynamics.

Microbial dispersal in unsaturated porous media: Characteristics of motile bacterial cell motions in unsaturated angular pore networks

“…Traditionally, ecologists assumed that organismic dispersal mimics diffusion; hence follow a normal distribution of individuals displacement step [Hapca et al, 2009]. However, as experimental results have shown, the dispersion distribution is often leptokurtic, with a peak near mean individual displacement and a fat tails relative to that of a normal distribution [Taylor, 1980;Nathan, 2001;Hawkes, 2009]. The fat tail of a leptokurtic distribution is an important trait that enhances effective dispersal relative to rates predicted for normal distribution [Yamamura et al, 2007].…”

When the going gets tough: behavioural type-dependent space use in the sleepy lizard changes as the season dries

“…Yet, the factors shaping spatial dynamics in natural systems remain poorly understood, presumably because animal movements result from complex feedbacks between the state and traits of focal individuals and their environment [1,2]. Well-known environmental factors include the local distribution of resources and competitors [3,4], but the effects of consistent behavioural differences among individuals within a population, remain elusive [5,6]. Such differences among individuals are often referred to as behavioural types (BTs) or animal personalities and here we test how BTs interact with ecological conditions to affect animal space use.…”

“…In particular, individuals that are more exploratory, bolder, more aggressive, or more asocial than others tend to disperse more frequently and over larger distances [12 -15]. Other BT-dependent aspects of space use may include home range (HR) size, relative use of patches that differ in resources or risks, and movement patterns [5,[16][17][18], but these have received less attention. Within-species differences in space use can generate spatial and temporal variability in interactions within and among species that can, in turn, have major impacts on population and community dynamics.…”

“…seasonal) dynamics, and how it interacts with spatio-temporal variation in ecological conditions are still poorly understood. Acknowledging BT-dependent space use can also help to advance the burgeoning field of movement ecology by ( partially) explaining the commonly observed intraspecific variation in movement patterns, and the deviations of individuals from theoretically expected optimal behaviours [5,6,16].…”

Measuring dispersal as distance-dependent recruitment rates: testing the performance of DDRR on simulated data

“…This should facilitate the connection between dispersal patterns observed and the behavior of the individuals moving (Bowler and Benton 2005;Dingemanse et al 2003;Greenwood 1980;Hawkes 2009;Russell and Rowley 1993).…”