Shrinking Tribes in Brazil

A team of scientists solve a long-standing floral mystery in Brazil.

Think of wildlife in Brazil and you're bound to imagine the Amazon rain forest. But south of the great Amazon River lies a very different but comparably diverse ecosystem known as "campo rupestre." Portuguese for "rocky fields," this habitat exists in island-like patches of quartz outcroppings on mountain slopes between 1,000 and 2,000 meters elevation. The soil is acidic and nutrient poor, and seasonal drought is a fact of life. Adapting to these harsh conditions, plants here have evolved similar traits: dwarf statures and small, thick, leathery leaves to conserve water. In fact, at a glance, many species in different families look identical.

Until now. Academy botanist Frank Almeda and Brazilian colleague Angela Martins from the State University of Campinas have redefined a group of campo rupestre plants, reducing its members by a third. Plants in a family dubbed "princess flowers" appear so similar that the large tribe Microlicieae was long thought to include 11 to 15 genera. But aware that convergent evolution can do tricky things, the duo set out in 1998 for a closer look.

After visiting 170 localities in three Brazilian states, Almeda and Martins analyzed hundreds of princess flowers. They dug deep for clues, scrutinizing fruits, seeds, flowers, and chromosomes. Sure enough, after four years of work, the team has found that evolution certainly has tricked scientists: about two-thirds of the original members didn't belong to Microlicieae, shrinking the group down to six genera. To put the icing on the cake, subsequent DNA studies with Academy colleague Peter Fritsch came up with identical results.

Web Links

Frank Almeda - Academy Curator
http://www.calacademy.org/research/curators/almeda.php

Peter Fritsch - Academy Curator
http://www.calacademy.org/research/curators/fritsch.php

Angela Martins
http://genos.cnpq.br:12010/dwlattes/owa/prc_imp_cv_int?f_cod=K4788610Y2

Science Now - Exploring Mesoamerica
http://www.calacademy.org/science_now/archive/academy_research/frank_almeda.php

Melostomataceae of the World
http://www.flmnh.ufl.edu/natsci/herbarium/melastomes/melastome_phylogenetics_table.php

Phylogenetic analysis of the Microlicieae
http://www.botany2002.org/section15/abstracts/30.shtml

South America - Centres of Plant Diversity
http://www.nmnh.si.edu/botany/projects/cpd/sa/sa-v.php

Campos Rupestres montane savanna
http://www.worldwildlife.org/wildworld/profiles/terrestrial/nt/nt0703_full.php

Frank Almeda displaying one of the specimens collected in a "rocky field" habitat of Minas Gerais, Brazil, along with Angela Martins, Professor of Botany at the University of Campinas (Brazil), and Peter Fritsch, Curator of Botany at the Academy. Photo: Renato Belinello.
Typical campo rupestre (rocky field) habitat, Diamantina Plateau, Minas Gerais, Brazil. Photo: Renato Belinello
Rhynchanthera grandiflora. Photo Frank Almeda.
Cambessedesia semidecandra. Photo Frank Almeda.