Data from: Evolution of cold tolerance in the highly stress tolerant samphires and relatives (Salicornieae: Amaranthaceae)”

Low temperature constitutes one of the main barriers to plant
distributions, confining many clades to their ancestrally tropical biome.
However, recent evidence suggests that transitions from tropical to
temperate biomes may be more frequent than previously thought. Here, we
study the evolution of cold and frost tolerance in the globally
distributed and highly stress-tolerant Salicornieae (Salicornioideae,
Amaranthaceae s.l.). We first generate a phylogenetic tree comprising
almost all known species (85-90%), using newly generated (n = 106) and
published nuclear-ribosomal and plastid sequences. Next, we use
geographical occurrence data to document in which clades and geographical
regions cold-tolerant species occur and reconstruct how cold tolerance
evolved. Finally, we test for correlated evolution between frost tolerance
and the annual life form. We find that frost tolerance has evolved
independently in up to four Northern Hemisphere lineages but that annuals
are no more likely to evolve frost tolerance than perennials, indicating
the presence of different strategies for adapting to cold environments.
Our findings add to mounting evidence for multiple independent
out-of-the-tropics transitions among close relatives of flowering plants
and raise new questions on the ecological and physiological mechanism(s)
of adaptation to low temperatures in Salicornieae.