only is deforestation concentrated in the tropics, where diversity is centered, but
tropical ectotherms have narrow thermal tolerances compared to temperate species,
rendering them especially vulnerable to warming (Hansen et al. 2013; Deutsch et al.
2008). Tropical plants do not have narrower thermal tolerances, but sit nearer to their
thermal limits, making them vulnerable through a different mechanism (Sentinella
et al. 2020). In between, are the many species with larger ranges or environmental
tolerances, as well as those in relatively protected sites, including those legally
protected, unsuitable for development, or in regions, like northeastern North America, which have shifted from net deforestation to reforestation (Rudel et al. 2020).
These species will have opportunities to relocate, acclimate, or adapt to the humanreconfigured planet. Along with altering the timing of activity and use of microhabitats, organisms will relocate to higher elevations in terrestrial systems and deeper
depths in marine systems, as well as range shifts and contractions toward the poles;
some will also respond to GCC with combinations of phenotypic plasticity and
adaptive genetic changes (Sgro et al. 2016; Scheffers et al. 2016; Pecl et al. 2017;
Parmesan 2006; Hastings et al. 2020).
16.2 Symbiotic Saviors or Achilles Heels?
One possible route to widespread and rapid acclimation and evolutionary change in
the face of climate disruption is through symbiosis, defined as the intimate and
prolonged living together of dissimilar organisms (Oliver and Russell 2016). Symbionts often confer novel properties on their hosts, including tolerance to a wide
range of biotic and abiotic stressors, which may increase odds of survival in a more
variable world. On the flip side, the net effects of climate change on organisms are
driven by species interactions, often surprisingly complex ones, rather than the
reactions of individual species. Hence specialized interactions, including many
symbioses, may be particularly vulnerable to climate perturbations (Wernegreen
2012; Renoz et al. 2019; Corbin et al. 2017; Blois et al. 2013).
One challenge in forecasting the roles of microbial symbionts in climate adaptation is that microbes are rarely considered in discussions of climate change, even
though temperature is a key determinant of microbial community diversity
(Thompson et al. 2017; Cavicchioli et al. 2019). Microbes perform major roles in
biogeochemical cycles, including carbon, nitrogen, and oxygen. They have modulated past climates, and in turn, have repeatedly adapted to changing climates.
Moreover, bacteria and archaea are exceptionally abundant (estimated at
1.2 Â 10
30 ), occurring, mostly in biofilms, across diverse marine and terrestrial
habitats (Flemming and Wuertz 2019). They are also the only known life forms in
the vast subsurface of the planet, as well as some aboveground extreme environments, including those that are very hot, cold, or salty, and ones that are highly acidic
or basic. Some of these microbes may have exaptations that facilitate eukaryote
persistence in the forthcoming world.
16 Symbiosis in a Rapidly Changing World
267
tropical ectotherms have narrow thermal tolerances compared to temperate species,
rendering them especially vulnerable to warming (Hansen et al. 2013; Deutsch et al.
2008). Tropical plants do not have narrower thermal tolerances, but sit nearer to their
thermal limits, making them vulnerable through a different mechanism (Sentinella
et al. 2020). In between, are the many species with larger ranges or environmental
tolerances, as well as those in relatively protected sites, including those legally
protected, unsuitable for development, or in regions, like northeastern North America, which have shifted from net deforestation to reforestation (Rudel et al. 2020).
These species will have opportunities to relocate, acclimate, or adapt to the humanreconfigured planet. Along with altering the timing of activity and use of microhabitats, organisms will relocate to higher elevations in terrestrial systems and deeper
depths in marine systems, as well as range shifts and contractions toward the poles;
some will also respond to GCC with combinations of phenotypic plasticity and
adaptive genetic changes (Sgro et al. 2016; Scheffers et al. 2016; Pecl et al. 2017;
Parmesan 2006; Hastings et al. 2020).
16.2 Symbiotic Saviors or Achilles Heels?
One possible route to widespread and rapid acclimation and evolutionary change in
the face of climate disruption is through symbiosis, defined as the intimate and
prolonged living together of dissimilar organisms (Oliver and Russell 2016). Symbionts often confer novel properties on their hosts, including tolerance to a wide
range of biotic and abiotic stressors, which may increase odds of survival in a more
variable world. On the flip side, the net effects of climate change on organisms are
driven by species interactions, often surprisingly complex ones, rather than the
reactions of individual species. Hence specialized interactions, including many
symbioses, may be particularly vulnerable to climate perturbations (Wernegreen
2012; Renoz et al. 2019; Corbin et al. 2017; Blois et al. 2013).
One challenge in forecasting the roles of microbial symbionts in climate adaptation is that microbes are rarely considered in discussions of climate change, even
though temperature is a key determinant of microbial community diversity
(Thompson et al. 2017; Cavicchioli et al. 2019). Microbes perform major roles in
biogeochemical cycles, including carbon, nitrogen, and oxygen. They have modulated past climates, and in turn, have repeatedly adapted to changing climates.
Moreover, bacteria and archaea are exceptionally abundant (estimated at
1.2 Â 10
30 ), occurring, mostly in biofilms, across diverse marine and terrestrial
habitats (Flemming and Wuertz 2019). They are also the only known life forms in
the vast subsurface of the planet, as well as some aboveground extreme environments, including those that are very hot, cold, or salty, and ones that are highly acidic
or basic. Some of these microbes may have exaptations that facilitate eukaryote
persistence in the forthcoming world.
16 Symbiosis in a Rapidly Changing World
267