Life
on earth is astonishingly diverse, and how diversity varies geographically,
among different taxonomic groups and through time, is intriguing. There are few
studies that investigated which evolutionary processes might explain current
macroalgae distribution patterns, or which traits might have been involved in
their evolutionary success. These studies have mainly focused on thermal affinities,
as it has been suggested that temperature is the most relevant abiotic factor
in survival and distribution of macroalgae. The main goal of this project was
to test macroevolutionary hypotheses of trait evolution in macroalgae across
geological timescales. The focus was drawn to two distinct taxonomic groups:
the green algal genus Codium, and
the red algal order Nemaliales. The first is a highly diverse genus, and
presents a variety of distinct morphologies. The latter comprises both
calcified and uncalcified taxa. Both groups are distributed from cold-temperate
waters to tropical regions. This latitudinal distribution range makes them
great models to investigate evolutionary dynamics over thermal gradients. The
results corroborate the strong influence of temperature in macroalgae
evolutionary history, but they also show that other traits may play an
evolutionary role. In the genus Codium it
was shown that taxa with higher temperature affinities present higher
diversification rates. However, morphology was also correlated with these
rates. In the order Nemaliales a correlation was found between the uncalcified
derived character, and the exploration of wider climatic niches during its
radiation. Projects like this one allow us to test hypotheses about the
evolutionary past, yielding exciting insights into the hidden history of the
evolution of life.