Conceptual models of the processes and patterns of the ecological, evolutionary and bio-geographical consequences of global climate changes
Authors: Cohen Dan 
Published: September 2014

A unifying conceptual model is constructed for the major effects of alternating periods of global warming and cooling and sea-level changes on the geographical distributions and the ecological and genetic characteristics of species and ecological communities.

The main results found are:

The species in the interior of continuous global latitude and altitude temperature gradients are expected to follow the moving temperature zones without any major extinctions or any major changes in their physiological and ecological characteristics and adaptive roles during both global warming and global cooling periods, with competitive replacement of resident species by zonally dispersing pre-adapted species.

Many or all of the existing species at all the global cold boundary zones of both latitude and altitude temperature gradients are expected to become extinct during periods of global warming, which would be caused by competitive displacement by immigrating pre-adapted species from adjacent warmer zones.

Most existing species in the warm boundary zones of all the global temperature gradients are predicted to persist and adapt without competition to the increased temperature during periods of global warming, and to diversify by adaptations to newly created ecological opportunities.

Periods of global cooling are predicted to cause analogous opposite effects to the effects of global warming in the cold and warm boundaries of temperature gradients: that is, extinctions at the warm boundaries and persistence and adaptations at the cold boundaries:

Existing species in all islands and island-like isolated areas are predicted to persist in the absence of competitive displacement by immigrating pre-adapted species, and gradually adapt to the changing temperatures during periods of both global warming and global cooling.

During periods of global cooling, many more diverse opportunities for new adaptations and for invasions by pre-adapted species are expected and predicted in the large diversity of the newly open heterogeneous coldest and highest altitude zones of all the global altitude temperature gradients.

Long-term sequences of alternating periods of global warming and global cooling are expected to cancel and eliminate most of the ecological and adaptive changes which have occurred during the previous periods at all the latitude and altitude boundary zones. The species at the interior of continuous temperature gradients are expected to persist unchanged over long evolutionary time during repeated sequences of alternating periods of global warming and global cooling.

The effects of higher and lower global sea levels on the sea shore and intertidal species and communities during periods of global warming or cooling are expected to be analogous to the bio-geographical, ecological and genetic changes caused or predicted by global warming or cooling in the species and communities in terrestrial or marine temperature gradients.

Global sea-level changes which cause higher or lower shifting of the levels of the ecological zones in continuous sea shore gradients are expected therefore to cause continuous tracking and moving of the populations of the unchanged zonally adapted species. On the other hand, zonally adapted sea shore species are expected to be displaced or become extinct during periods of sea-level changes at the higher or lower boundary zones of the sea-level gradients in semi-isolated marine basins, and in locally discontinuous, fragmented or truncated sea shore ecological gradients.