**4. Riverine barriers**

434 Ecosystems Biodiversity

differentiation along the Brazilian Atlantic Forest, and showed an expansion signal in lower latitudes (Pavan et al. 2011, Grazziotion et al. 2006, Martins et al. 2009). However, these studies did not report higher genetic diversity in northern population (lower latitudes), as it

Fig. 2. Summary maps of historically stable areas for the Atlantic forest definitions, obtained by(1) Carnaval and Moritz (2008) summing across BIOCLIM and MAXENT output grids for

The Atlantic margin of the South American plate is tectonically passive (see Thomé et al. 2010), although little changes occur, causing faults and fractures and consequently affect dated sedimentary deposits, regional uplifts consequently remodeling the landscape (Ricommini & Assumpção 1999). In the Brazilian Atlantic Forest many changes may have been caused by the uplift of the coastal Brazilian mountains (Serra do Mar). Those events possibly interrupted precipitation in southeastern Brazil by the early Pliocene at about 5.6 Ma and therefore altered the distribution of humid and dry habitats. This period coincides with the transition from tropical humid to semiarid or arid conditions described by some authors (Simpson 1979; Vasconcelos *et al*. 1992). This orogenic process deeply changed the geomorphologic and climatic conditions of south and southeast areas of Brazil, and consequently fragmented Brazilian Atlantic Forest with drier areas (Grazziotini et al. 2006). The palynological record of the Quartenary showed that between 33,000 and 25,000 years ago, the central Brazilian region was moister than today and was covered by rainforest (Ledru 1993), and during the last glaciation (18,000-12,000 years ago) the present day corridor of xeric vegetation was covered by extensive woodland (Prado & Gibbs 1993, Costa et al. 2003). It is believed that during drier periods, forest formations

forest absence/presence under current and (2) Thomé *et al.* (2010) models of habitat distribution for current time, last interglacial period (LIG), last glacial maximum period

would be expected under gradient hypothesis.

(LGM),.

**3. Neotectonic hypothesis** 

The rivers can play an important role in biological diversification as they may act as primary or secondary barriers to gene flow and may have been important to model the current biota distribution. Siedchlang et al. (2010) suggest that the São Francisco River was an important barrier to *Calyptommatus* (lizards)*,* allowing speciation on opposite margins of the river, being responsible to present distribution of *C. sinebrachiatus* and *C. leiolepis*, as well as that of *C. nicterus* and *C. leiolepis*, which occurred in adjacent banks on opposite margins. Thomé et al. (2010) observed that *Rhinella crucifier* group presents divergent lineages spatially concordant with Doce River systems and refute the refuges model to diversification this group. Also, Lacerda *et al.* (2007) presented genetic data that suggested a role of the Jequitinhonha river and Doce river for separating populations of passeriformes *Thamnophilus ambiguous* (Sooretama). Pellegrino *et al*. (2005) show also that the genetic structure of lizards of the *Gymnodactylus darwinii* complex coincides with the river system in the northern regions of the Brazilian Atlantic Forest and that major coastal rivers in this region may have played a key role in its diversification

On the other hand, D´Horta et al. (2011) suggested for *Sclerurus scansor* that tectonic activity associated with the Paraiba Valley can be congruent with the scenario that the river was important for the secondary contact of lineages of the south and central of Atlantic Forest, but not for the origin of these lineages due to phylogeography rupture, because the divergence time is much more recent (middle/late Pleistocene). This hypothesis of secondary contact among lineages is corroborated by Cabanne et al. (2007) and Pessoa (2008), who also suggested Paraíba do Sul Valley as contact region of divergent mitochondrial lineages from *Xyphorhynchus fuscus* and *Conopophoga lineata.* Furthermore, in both margins of the Paranapanema river were also found two phylogroups of *Bothrops jararaca* (Grazziotin et al. 2006).

In summary, the riverine systems seem important to differentiation between lineages and species, thus, are relevant to consider in the evolutionary processes related to the Atlantic Forest diversification, mainly the São Francisco, Jequitinhonha, Doce and Paranapanema (Fig 3).

How Past Vicariant Events Can Explain the Atlantic Forest Biodiversity? 437

related to change by drift in different populations historically isolated, or by selective change in different forest types. They found that the plumage variation was related to different forest types and not to historically isolated lineages, suggesting an important role of selection. *D. platyrostris* at the open vegetation corridor was lighter and less streaked than at the forest habitat, a morph which is suggested to be an adaptation of woodcreepers for habitats with high luminosity levels, as are forests at the open vegetation corridor (Marantz, 1997; Willis, 1992). On the other hand, rainforest individuals are darker and more streaked, what is considered to be an adaptation to live in low luminosity and very humid conditions

**Era Period Epoch MYA Event Reference** 

Pleistocene 1.8 Divergence lineage from *Sclerurus* 

Divergence of lineages from South

Divergence between lineages of

Divergence of lineages of *Rhinella* 

Forest (toad)

 Divergence of lineages of *Desmodus rotundus* (bat)

Divergence of lineages of *Bradypus* 

Divergence of lineages of North and

Pliocene 5.3 Divergence of phylogrops *of* 

Uplift Brazilian coast mountain

Divergence of lineages North and

(Lizards)

Table 1. The geological time scale and the resume of principal studies of Phylogeography in

Neogene

*torquatus* (Xenarthra)

*Bothrops jararaca* (Serpentes)

south of *Rhinella crucifier* (toad)

Miocene 23.0 Drainage of Parana river Grazziotin et al.

South Gymnodactylus darwinii

sediments of the Barreiras Formation Doce River

Divergence of lineages of

Divergence of lineages of

*scansor* (Passeriformes)

*Xyphorhynchus fuscus* (Passeriformes)

*Carollia perspicillata* (bat)

*Conopophoga lineata* (Passeriformes)

the *Gymnodectylus darwinii* (lizards)

*crucifier* center and north Atlantic

D´Horta et al.

Cabanne et al.

Pessoa 2008

Pavan et al. 2011

Thomé et a. 2010

Martins et al.

Moraes-Barros et al. 2006

Grazziotini et al. 2006.

Thomé et a. 2010

Pellegrino et al.

Pellegrino et al.

2011

2007

2005

2009

2006

2005

(Marantz, 1997; Willis, 1992; Zink & Remsen, 1986).

Holocene 0.01

**CENOZOIC Quartenary** 

**Tertiary** 

Atlantic Forest

Fig. 3. Localization of mainly rivers that influence the distribution of species at Brazilian Atlantic Forest.
