= Solution
<Plate tectonics> changes the environments in which <evolution> operates: it redistributes habitats, supplies and buries nutrients, and helps regulate <climate>. It does not prescribe the direction of <evolution>, and its presence neither guarantees <life> nor demonstrates that <life> could not persist under another tectonic regime.
\b[Long-term environmental regulation.] <Seafloor spreading> and <subduction> exchange material between the <mantle>, <crust>, <ocean> and <atmosphere>. <Volcanism> and <metamorphism> release <carbon dioxide>, while exposure of fresh <silicate minerals> by <tectonic uplift> and <erosion> can promote <chemical weathering>. Coupled <silicate weathering> and <carbonate> burial remove <carbon dioxide> from the surface system. In a simplified net reaction,
$$
\mathrm{CaSiO_3+CO_2\longrightarrow CaCO_3+SiO_2}.
$$
The <carbonate-silicate cycle> can provide a <negative feedback>: warming and greater runoff can accelerate <silicate weathering>, lowering atmospheric <carbon dioxide> and weakening the <greenhouse effect>. This requires available fresh rock and <liquid water>; a supply-limited <chemical weathering> regime need not respond strongly to warming. <Plate tectonics> therefore helps sustain some long-lived habitable environments without acting as an infallible thermostat.<A negative feedback mechanism for the long-term stabilization of Earth's surface temperature by James C. G. Walker and others>[1981, abstract and weathering feedback model]{ref}
\b[Nutrients and oxygenation.] <Tectonic uplift>, <erosion> and <hydrothermal circulation> supply nutrients such as <phosphorus> and <iron> to surface environments. Changes in <continental configuration>, <continental shelf> area and <ocean circulation> alter <primary production>, nutrient recycling and <ocean anoxia>. Burial of <organic carbon> and reduced <sulfur> can leave an oxidizing surface budget, whereas reduced volcanic gases and freshly exposed reduced rock consume oxidants. Thus <plate tectonics> can influence atmospheric <oxygen> and the ecological opportunities for <aerobic respiration>, but the sign depends on competing fluxes rather than simply on the amount of <volcanism>.
\b[Geographical isolation and environmental diversity.] <Continental rifting> separates populations, favoring <allopatric speciation>; <continental collision> and the emergence of land bridges can reconnect populations, enabling dispersal and competition. Opening or closing <ocean gateways> changes <ocean circulation> and <heat transport>. <Mountain building> creates elevational habitats and <rain shadows>; changing <continental shelf> area changes shallow-water habitat. These processes can promote diversification, eliminate habitats or both. A proposed biological response should be tested against independently dated <paleogeography> and the <fossil record>, accounting for unequal preservation.
\b[Abrupt disturbances.] Large episodes of <volcanism>, including a <large igneous province>, can rapidly perturb the <carbon cycle>, <ocean acidification> and <ocean anoxia>; <sulfur dioxide> aerosols can instead produce shorter cooling episodes. Such disturbances may cause <mass extinction>, followed by ecological release and diversification of survivors. A <mantle plume> need not originate at a <plate boundary>, so association with a tectonically active planet is not proof that horizontal <plate motion> directly caused every eruption. The relevant reasoning links a dated geological forcing to its environmental effects and then to biological selectivity, rather than attributing all biological crises to <plate tectonics>.
Over billions of years, <plate tectonics> can repeatedly create habitable environments and new selective pressures. Nevertheless, models allow <carbon cycling> and habitable <climate> on some <stagnant-lid planets>. This makes <plate tectonics> a plausible contributor to sustained environmental diversity, not a demonstrated universal requirement for <evolution>.<Carbon Cycling and Habitability of Earth-Sized Stagnant Lid Planets by Bradford J. Foley and Andrew J. Smye>[2018, coupled thermal and carbon-cycle models]{ref}
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