Incorporating the geometry of dispersal and migration to understand spatial patterns of species distributions

Abstract

Dispersal and migration can be important drivers of species distributions. Because the paths followed by individuals of many species are curvilinear, spatial statistical models based on rectilinear coordinates systems would fail to predict population connectivity or the ecological consequences of migration or species invasions. I propose that we view migration/dispersal as if organisms were moving along curvilinear geometrical objects called smooth manifolds. In that view, the curvilinear pathways become the 'shortest realised paths' arising from the necessity to minimise mortality risks and energy costs. One can then define curvilinear coordinate systems on such manifolds. I describe a procedure to incorporate manifolds and define appropriate coordinate systems, with focus on trajectories (1D manifolds), as parts of mechanistic ecological models. I show how a statistical method, known as 'manifold learning', enables one to define the manifold and the appropriate coordinate systems needed to calculate population connectivity or study the effects of migrations (e.g. in aquatic invertebrates, fish, insects and birds). This approach may help in the design of networks of protected areas, in studying the consequences of invasion, range expansions, or transfer of parasites/ diseases. Overall, a geometrical view to animal movement gives a novel perspective to the understanding of the ecological role of dispersal and migration.

Fine‐scale seascape genomics of an exploited marine species, the common cockle Cerastoderma edule, using a multimodelling approach

“…This approach identifies well-connected population groups as well as weakly connected, partially connected or isolated populations. These simulations highlight the importance of local and mesoscale hydrodynamics interacting with species-specific larval behaviours in driving population persistence (Bode et al, 2019;Botsford et al, 2009;North et al, 2008;Robins et al, 2013) and recovery from stock decline (Gimenez, 2019). They highlight how the capacity of a population to recover from mass mortalities is contingent on the scale of disturbance relative to the scale of connectivity (Masier & Bonte, 2019).…”

“…They can also indicate the potential for resilience to environmental change (Razgour et al, 2019). Connectivity between marine populations is central to their health and resilience to external pressures such as parasites and pathogens (Rowley et al, 2014), pollution, human exploitation and climate change over ecological and evolutionary timescales (Burgess, Bowring, & Shen, 2014;Cowen & Sponaugle, 2009;Gimenez, 2019). For these reasons, it is vital to distinguish between neutral variation and adaptive divergence when attempting to understand what drives the observed population structure in marine organisms.…”

Connectivity between populations of the scallop Pecten maximus in the Irish Sea and the implications for fisheries management

“…Predictions of connectivity and selfrecruitment can help explain the species' genetic structure, population dynamics, and aid in the management of the ecosystem or resource (Crooks and Sanjayan, 2006;Botsford et al, 2009;Nicolle et al, 2013). Species that experience population decline from disease or exploitation can eventually recover via self-recruitment and/or larval flow from connecting populations, provided the connectivity network is sufficient (Grimm et al, 2003;Gimenez, 2019). Therefore, there is a strong incentive to characterise connectivity networks for a range of ecologically sensitive and commercially important marine species (Miller, 2007).…”

Characterization of Some Commercially Important Octopus (Mollusca: Cephalopoda) from Indonesian Waters using Mitochondrial DNA Cytochrome Oxidase Sub-Unit I (Mt-DNA COI)

“…The continued capture of large numbers of octopuses without the correct identification of the species allows for the accidental overexploitation of certain species. This overexploitation can lead to the extinction of this species (Nieuwenhove et al, 2019), although this may also occur due to several factors such as parasites and pathogens (Rowley et al, 2014), pollution, exploitation and climate change (Gimenez, 2019).…”