Evolution of Suites of Traits in Response to Environmental Stress

TLDR

Plant traits that enable exploitation of low‑resource environments are physiologically linked to growth‑related traits, and similar trait suites arise as plastic and evolutionary responses to stress, a pattern seen across many animal taxa. The authors propose that a genetic change in a switch or underlying trait that broadens the expression of a stress‑resistance syndrome can convert a high‑resource genotype into a stress‑tolerant one, and that rapid evolution may allow short‑lived species to adapt to human‑induced change and aid crop development. Because growth‑related traits are physiologically linked to the syndrome, heritable changes in key growth traits pleiotropically affect the syndrome, so alterations in these traits can drive evolution of the entire stress‑resistance suite. Evidence includes single‑gene mutants with multiple stress traits, rapid evolution of metal‑tolerant populations, and consistent trait patterns along resource gradients, though long‑lived species may lag behind rapid global change.

Abstract

Traits that enable plants to exploit low-resource environments (e.g., slow tissue turnover, low transpiration rate, high root: shoot ratio, and high concentrations of plant defenses against pathogens and herbivores) are physiologically linked to key growth-related traits (low rates of photosynthesis, nutrient uptake, and growth). Similar suites of traits occur as both phenotypically plastic and evolutionary responses to stress. We suggest that a genetic change in a switch or underlying trait that turns on this stress resistance syndrome (SRS), which causes it to be expressed over a wider range of environmental circumstances, would effectively convert a high-resource genotype into one that is more stress-tolerant. Because of physiological linkages between growth-related traits and the SRS, any heritable change in a key growth-related trait will pleiotropically affect the SRS. Therefore, heritable changes in these key growth-related traits could be accompanied by evolution of the entire SRS. Evidence for this hypothesis comes from single-gene mutants that differ in many stress-related traits, rapid evolution of metaltolerant populations that are broadly stress-resistant, and consistent patterns of traits in species along gradients in resource availability. Similar evolutionary patterns occur in many animal taxa, which suggests that it is a general evolutionary phenomenon. We suggest that rapid evolution in response to changing environmental stress may allow many short-lived species to respond to human-induced environmental change and provide opportunities to develop stress-resistant crops. However, the time lag between generations of long-lived species that dominate most natural vegetation may not allow mature individuals of these species to keep pace with rapid global change