**2. The Neotropical floristic kingdom**

The word *Neotropic* (from the Greek *neos =* "new") refers to the tropical region of the American continent (Antonelli & Sanmartín, 2011), or "New World" – a term coined by Peter Martyr d' Anghiera in 1493, shortly after Christopher Columbus's first voyage to the Americas (O'Gorman, 1972). As currently defined (Schultz, 2005), the Neotropical kingdom extends from central Mexico, in the north, to southern Brazil, in the south, including Central America, the Caribbean islands and most of South America.

In the Neotropics, equatorial and tropical climates predominate with low climatic seasonality, when compared with kingdoms with cold and temperate climates. Precipitation and annual mean temperatures are generally high, but there is great regional variation (Antonelli & Sanmartín, 2011). Before human colonization, the rain forest of Amazonia accounted for about one third of the entire South American continent. There are, however, several other terrestrial biomes in the Neotropics that are noteworthy for their size and ecological importance, such as the Cerrado and the Atlantic forest of eastern Brazil (Antonelli & Sanmartín, 2011).

The outstanding species richness found today in the Neotropics has remained elusive in our understanding of the evolution of life on Earth (Antonelli & Sanmartín, 2011). Comprising around 90,000–110,000 species of seed plants, the Neotropics alone harbours about 37% of the world's species, more than tropical Africa (30,000–35,000 spp.) and tropical Asia and Oceania combined (40,000–82,000 spp.) (Govaerts, 2001; Thomas, 1999). Sanmartín and Antonelli punctuated the factors that can explain this high species richness (Antonelli & Sanmartín 2011 and references therein). They are related 1) with the geographical position of Central and South America, resulting largely in tropical and equatorial climates; 2) edaphic heterogeneity; 3) biotic interactions that promote speciation mechanisms; 4) relatively stable environments over time, resulting in very ancient ecosystems that conserve niches; 5) adaptive radiation favoured by the great ability of dispersal of flowering plants; 6) geographic isolation (only 3.0 million years ago, South America became connected to North and Central America by the Isthmus of Panama); 7) climatic fluctuations of Pleistocene, leading to formation of refuges for many isolated populations and allopatric speciation; 8) uplift of the Andean cordillera, occurred largely in the last 25 million years; and 9) the profound change in the vast hydrological systems, especially in the Amazon region.

During millions of years there was a synergism between gradual and slow climate changes and speciation, giving time for natural selection and other evolutionary tolls to play their role. The final result of this long process of genesis and evolution of the Neotropical region, is that most of the Neotropical countries, such as Brazil, Colombia, Ecuador and Peru, are on the higher positions of any ranking of species richness. Brazil, in particular, occupies the first position in such rankings and is therefore considered the most Megadiverse country.

Neotropical kingdom is divided into Caribbean, Guayana Highlands, Amazonian, Brazilian and Andean region (Takhtajan, 1986). Brazilian region is, in turn, subdivided into the provinces of the Caatinga, the highlands of central Brazil, Chaco, Atlantic, and Paraná (Takhtajan, 1986). In the Brazilian territory, major biomes are spread over these provinces, such as the Caatinga, Cerrado, Atlantic Forest, Pantanal and Pampas. Even in the case of a predominantly tropical region, where, typically, there is less thermal seasonality and spatial climate variations than in temperate regions, there are important environmental variations

The word *Neotropic* (from the Greek *neos =* "new") refers to the tropical region of the American continent (Antonelli & Sanmartín, 2011), or "New World" – a term coined by Peter Martyr d' Anghiera in 1493, shortly after Christopher Columbus's first voyage to the Americas (O'Gorman, 1972). As currently defined (Schultz, 2005), the Neotropical kingdom extends from central Mexico, in the north, to southern Brazil, in the south, including Central

In the Neotropics, equatorial and tropical climates predominate with low climatic seasonality, when compared with kingdoms with cold and temperate climates. Precipitation and annual mean temperatures are generally high, but there is great regional variation (Antonelli & Sanmartín, 2011). Before human colonization, the rain forest of Amazonia accounted for about one third of the entire South American continent. There are, however, several other terrestrial biomes in the Neotropics that are noteworthy for their size and ecological importance, such as the Cerrado and the Atlantic forest of eastern Brazil

The outstanding species richness found today in the Neotropics has remained elusive in our understanding of the evolution of life on Earth (Antonelli & Sanmartín, 2011). Comprising around 90,000–110,000 species of seed plants, the Neotropics alone harbours about 37% of the world's species, more than tropical Africa (30,000–35,000 spp.) and tropical Asia and Oceania combined (40,000–82,000 spp.) (Govaerts, 2001; Thomas, 1999). Sanmartín and Antonelli punctuated the factors that can explain this high species richness (Antonelli & Sanmartín 2011 and references therein). They are related 1) with the geographical position of Central and South America, resulting largely in tropical and equatorial climates; 2) edaphic heterogeneity; 3) biotic interactions that promote speciation mechanisms; 4) relatively stable environments over time, resulting in very ancient ecosystems that conserve niches; 5) adaptive radiation favoured by the great ability of dispersal of flowering plants; 6) geographic isolation (only 3.0 million years ago, South America became connected to North and Central America by the Isthmus of Panama); 7) climatic fluctuations of Pleistocene, leading to formation of refuges for many isolated populations and allopatric speciation; 8) uplift of the Andean cordillera, occurred largely in the last 25 million years; and 9) the

profound change in the vast hydrological systems, especially in the Amazon region.

During millions of years there was a synergism between gradual and slow climate changes and speciation, giving time for natural selection and other evolutionary tolls to play their role. The final result of this long process of genesis and evolution of the Neotropical region, is that most of the Neotropical countries, such as Brazil, Colombia, Ecuador and Peru, are on the higher positions of any ranking of species richness. Brazil, in particular, occupies the first position in such rankings and is therefore considered the most Megadiverse country.

Neotropical kingdom is divided into Caribbean, Guayana Highlands, Amazonian, Brazilian and Andean region (Takhtajan, 1986). Brazilian region is, in turn, subdivided into the provinces of the Caatinga, the highlands of central Brazil, Chaco, Atlantic, and Paraná (Takhtajan, 1986). In the Brazilian territory, major biomes are spread over these provinces, such as the Caatinga, Cerrado, Atlantic Forest, Pantanal and Pampas. Even in the case of a predominantly tropical region, where, typically, there is less thermal seasonality and spatial climate variations than in temperate regions, there are important environmental variations

**2. The Neotropical floristic kingdom** 

(Antonelli & Sanmartín, 2011).

America, the Caribbean islands and most of South America.

that create significant intra-regional heterogeneity. This fact can be explained by: 1) large latitudinal variation found, the northern boundary of the region is located around 3 ° S, and the south boundary, around 33 ° S latitude; 2) great altitudinal variation, with elevations ranging from sea level to mountainous regions that can reach approximately 2900 meters of altitude; 3) wide edaphic variation, the result of different soil genesis processes over time and space and 4) continentality, which determines a lower overall level of humidity and higher thermic amplitude, the most distant of the Atlantic Ocean. This great heterogeneity, combined with the inherent environmental characteristics of tropical regions that favor the development of life, and added to the climate and geological history of the entire Neotropic, which favored isolation and speciation, have provided to these biomes, in terms of floristic and physiognomy, a high species richness, high endemism and great structural complexity.

According to the Brazilian Institute of Geography and Statistics - IBGE (2004), Atlantic Forest biome constitutes the extra-Amazonian forest large set of South America, formed by rainforests (dense, open and mixed) and seasonal (deciduous and semideciduous). It comprises an environmental complex that includes mountain ranges, plateaus, valleys and plains of the entire eastern Brazilian Atlantic continental band. In southern and southeastern Brazil, it expands westward, reaching the borders of Paraguay and Argentina, also advancing on the southern highlands of Brazil, reaching the state of Rio Grande do Sul.
