geoecodynamics

frontiers of geobiology

Geoecodynamics – Scope

Now, more on the actual epistemological foundations and scope of Geoecodynamics. It expands geobiological theory by exploiting the historical record maintained in the genomes of living organisms. Patterns in DNA variation – the Genomic Record – can be quantified and applied to reconstruct events in the evolution of species. DNA variation holds signatures of Earth history, which can be read in the context of the palaeoecology ecology of the individual species –  Biotic Indicators of evolving landscapes and their palaeoenvironments. The spatio-temporal resolution of insights that we can read into evolutionary history is contingent on speciation events and key demographic events, which occurred in the life history of the species.

In its formal articulation (Cotterill & de Wit 2011), Geoecodynamics aims to elucidate the tempo and mode of drivers of landscape and palaeoenvironmental dynamics. I argue that studying biodiversity dynamics as an earth surface process – in the currency of the genomic record – provides the platform for the earth and life sciences to realize a Geobiotic Theory of Landscape Evolution.

One the powerful strengths of this pioneering science is its ability to resolve details cryptic events in the tectonic history of regional landscapes; these events revealed in the genomic record are too often transparent to orthodox geomorphological and geochronological methods, and the latter lack spatial resolution. For example, the geobiotic events recovered in the phylogeographic records of Africa’s Tigerfishes (Genus Hydrocynus) constrained major events in the Neogene rifting of the African Plate. Geobiotic events in these biotic indicators not only corroborate the geochronological evidence available, but extend the narrative of Africa’s rifting history. Phylogeographic records of Hydrocynus resolve several drainage rearrangements that in turn constrain rifting events otherwise lacking in any geochronological constraints (Goodier et al. 2011).

Individual events in species’ evolution are the proxies, with which we can constrain the tenures of discrete landforms – and other aspects of palaeoenvironments – in the evolving landscape. Insights are gleaned into turnovers of species focus on the births and deaths and other major demographic events in species’ tenures can be linked to the habitats and thus landforms within which biodiversity dynamics have tracked formative events in evolving landscapes (their landforms and palaeoenvironments). Ecological specialists – stenotopes – are ideal biotic indicators, because these species are more tightly confined by the local ecophysiological conditions of respective habitat patches. Habitats comprising the ecospace matrix correspond to the geospace: the landforms comprising the evolving landscape. Aquatic species dependent on wetlands, and troglobitic species in caves are superb examples of stenotopes whose evolution has been locked into specific landforms; tighter niche constraints contain the spatial demographics of such species, and their sensitivity to events that modify the landscape. More formally, it links the vibrant research area of niche modelling, in ecology, directly into geoecodynamics; albeit geoecodynamics recasts focuses on the dynamics of genomic variation of species respective to their niches in evolving landscapes.

This brief kinematic overview of geoecodynamics so presented here is obviously scale-free. We can use the categories ‘landform’, ‘species’ and ‘niche’ to study and reconstruct the interplay between the biota and the landscape at evolutionary scales. The specifics of demographic processes in the different species have played out through space and time across the landscape mosaic (its patches of landforms). Not only are the spatio-temporal domains containing biotic dynamics are complex but they are also diverse. These make for fortuitous circumstances for Geoecodynamics. The extant biodiversity presents the investigator with no shortage of biotic indicators of landscape dynamics. One of the most exciting arenas of this new approach lies in testing how far – and where – we can explore these dynamics, and map out their corresponding patterns of genomic variation shaped within the individuated histories of complex dynamic landscapes.

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