Limits...
Biogeographic history and cryptic diversity of saxicolous Tropiduridae lizards endemic to the semiarid Caatinga.

Werneck FP, Leite RN, Geurgas SR, Rodrigues MT - BMC Evol. Biol. (2015)

Bottom Line: The phylogenetic and population structures are intrinsically associated with stable rock surfaces and landscape rearrangements, such as the establishment of drainage basins located to the northern and southern distribution ranges.The T. semitaeniatus complex preserved high genetic diversity during range expansion, possibly as a result of frequent long-distance dispersal events.Our results indicate that both the current course of the São Francisco River and its paleo-courses had an important role in promoting diversification of the Caatinga endemic T. semitaeniatus species group.

View Article: PubMed Central - PubMed

Affiliation: Programa de Coleções Científicas Biológicas, Instituto Nacional de Pesquisas da Amazônia, Av. André Araújo 2936, 69060-000, Manaus, AM, Brazil. fewerneck@gmail.com.

ABSTRACT

Background: Phylogeographic research has advanced in South America, with increasing efforts on taxa from the dry diagonal biomes. However, the diversification of endemic fauna from the semiarid Caatinga biome in northeastern Brazil is still poorly known. Here we targeted saxicolous lizards of the Tropidurus semitaeniatus species group to better understand the evolutionary history of these endemic taxa and the Caatinga. We estimated a time-calibrated phylogeny for the species group based on two mitochondrial and two nuclear genes and jointly estimated the species limits and species tree within the group. We also devoted a denser phylogeographic sampling of the T. semitaeniatus complex to explore migration patterns, and the spatiotemporal diffusion history to verify a possible role of the São Francisco River as a promoter of differentiation in this saxicolous group of lizards.

Results: Phylogenetic analysis detected high cryptic genetic diversity, occurrence of unique microendemic lineages associated with older highlands, and a speciation history that took place during the Pliocene-Pleistocene transition. Species delimitation detected five evolutionary entities within the T. semitaeniatus species group, albeit with low support. Thus, additional data are needed for a more accurate definition of species limits and interspecific relationships within this group. Spatiotemporal analyses reconstructed the geographic origin of the T. semitaeniatus species complex to be located north of the present-day course of the São Francisco River, followed by dispersal that expanded its distribution towards the northwest and south. Gene flow estimates showed higher migration rates into the lineages located north of the São Francisco River.

Conclusions: The phylogenetic and population structures are intrinsically associated with stable rock surfaces and landscape rearrangements, such as the establishment of drainage basins located to the northern and southern distribution ranges. The T. semitaeniatus complex preserved high genetic diversity during range expansion, possibly as a result of frequent long-distance dispersal events. Our results indicate that both the current course of the São Francisco River and its paleo-courses had an important role in promoting diversification of the Caatinga endemic T. semitaeniatus species group.

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Localities sampled for the Tropidurus semitaeniatus species group and outgroups. Limits of the Caatinga are outlined in black and the current São Francisco River configuration in blue. Numbers correspond to locality names in Table 1 and colored symbols follow the same colors for clades in Figure 2. The white star right by locality number 50 is the type locality for T. semitaeniatus (Sincorá Velho, BA). The major geomorphological features discussed in the text are highlighted (AraPl = Araripe Plateau; CCHigh = Central Ceará Highlands/Serra da Ibiapaba, JaVa = Jaguaribe river valley, BoPl = Borborema Plateau). Major paleocourse phases of the SFR correspond to: (a) early opening to the equatorial Atlantic Ocean; (b) paleolacustrine phase; (c) forsaken meanders located to the south of the present mouth; and (d) the current course.
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Fig1: Localities sampled for the Tropidurus semitaeniatus species group and outgroups. Limits of the Caatinga are outlined in black and the current São Francisco River configuration in blue. Numbers correspond to locality names in Table 1 and colored symbols follow the same colors for clades in Figure 2. The white star right by locality number 50 is the type locality for T. semitaeniatus (Sincorá Velho, BA). The major geomorphological features discussed in the text are highlighted (AraPl = Araripe Plateau; CCHigh = Central Ceará Highlands/Serra da Ibiapaba, JaVa = Jaguaribe river valley, BoPl = Borborema Plateau). Major paleocourse phases of the SFR correspond to: (a) early opening to the equatorial Atlantic Ocean; (b) paleolacustrine phase; (c) forsaken meanders located to the south of the present mouth; and (d) the current course.

Mentions: However, most of the studies originally addressing Neotropical diversification have focused on taxa restricted to rainforests. Only more recently, investigators also aimed to understand biogeographic patterns of species distributed across the wide-ranging corridor of open-dry habitats that separates the two largest forested biomes in South America, the Atlantic and Amazon rainforests [5,9,11-15]. The open-dry formations, often collectively referred to as the dry diagonal biomes, extend in a NE–SW direction from the semiarid Caatinga of northeastern Brazil to the dry Chaco in Argentina, Bolivia and Paraguay, across the Cerrado savanna of central Brazil (Figure 1 at [11]). While recent investigations have focused on the diversification of herpetofauna groups that are either endemic or typical of the Cerrado [12,16], or broadly distributed across all biomes [5,9,17], no study to date addressed lizard taxa endemic to the biomes located at the extremes of the dry diagonal, namely the Chaco and Caatinga. The latter constitutes the largest nuclei of Seasonally Dry Tropical Forests (SDTF) in South America.Figure 1


Biogeographic history and cryptic diversity of saxicolous Tropiduridae lizards endemic to the semiarid Caatinga.

Werneck FP, Leite RN, Geurgas SR, Rodrigues MT - BMC Evol. Biol. (2015)

Localities sampled for the Tropidurus semitaeniatus species group and outgroups. Limits of the Caatinga are outlined in black and the current São Francisco River configuration in blue. Numbers correspond to locality names in Table 1 and colored symbols follow the same colors for clades in Figure 2. The white star right by locality number 50 is the type locality for T. semitaeniatus (Sincorá Velho, BA). The major geomorphological features discussed in the text are highlighted (AraPl = Araripe Plateau; CCHigh = Central Ceará Highlands/Serra da Ibiapaba, JaVa = Jaguaribe river valley, BoPl = Borborema Plateau). Major paleocourse phases of the SFR correspond to: (a) early opening to the equatorial Atlantic Ocean; (b) paleolacustrine phase; (c) forsaken meanders located to the south of the present mouth; and (d) the current course.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4494643&req=5

Fig1: Localities sampled for the Tropidurus semitaeniatus species group and outgroups. Limits of the Caatinga are outlined in black and the current São Francisco River configuration in blue. Numbers correspond to locality names in Table 1 and colored symbols follow the same colors for clades in Figure 2. The white star right by locality number 50 is the type locality for T. semitaeniatus (Sincorá Velho, BA). The major geomorphological features discussed in the text are highlighted (AraPl = Araripe Plateau; CCHigh = Central Ceará Highlands/Serra da Ibiapaba, JaVa = Jaguaribe river valley, BoPl = Borborema Plateau). Major paleocourse phases of the SFR correspond to: (a) early opening to the equatorial Atlantic Ocean; (b) paleolacustrine phase; (c) forsaken meanders located to the south of the present mouth; and (d) the current course.
Mentions: However, most of the studies originally addressing Neotropical diversification have focused on taxa restricted to rainforests. Only more recently, investigators also aimed to understand biogeographic patterns of species distributed across the wide-ranging corridor of open-dry habitats that separates the two largest forested biomes in South America, the Atlantic and Amazon rainforests [5,9,11-15]. The open-dry formations, often collectively referred to as the dry diagonal biomes, extend in a NE–SW direction from the semiarid Caatinga of northeastern Brazil to the dry Chaco in Argentina, Bolivia and Paraguay, across the Cerrado savanna of central Brazil (Figure 1 at [11]). While recent investigations have focused on the diversification of herpetofauna groups that are either endemic or typical of the Cerrado [12,16], or broadly distributed across all biomes [5,9,17], no study to date addressed lizard taxa endemic to the biomes located at the extremes of the dry diagonal, namely the Chaco and Caatinga. The latter constitutes the largest nuclei of Seasonally Dry Tropical Forests (SDTF) in South America.Figure 1

Bottom Line: The phylogenetic and population structures are intrinsically associated with stable rock surfaces and landscape rearrangements, such as the establishment of drainage basins located to the northern and southern distribution ranges.The T. semitaeniatus complex preserved high genetic diversity during range expansion, possibly as a result of frequent long-distance dispersal events.Our results indicate that both the current course of the São Francisco River and its paleo-courses had an important role in promoting diversification of the Caatinga endemic T. semitaeniatus species group.

View Article: PubMed Central - PubMed

Affiliation: Programa de Coleções Científicas Biológicas, Instituto Nacional de Pesquisas da Amazônia, Av. André Araújo 2936, 69060-000, Manaus, AM, Brazil. fewerneck@gmail.com.

ABSTRACT

Background: Phylogeographic research has advanced in South America, with increasing efforts on taxa from the dry diagonal biomes. However, the diversification of endemic fauna from the semiarid Caatinga biome in northeastern Brazil is still poorly known. Here we targeted saxicolous lizards of the Tropidurus semitaeniatus species group to better understand the evolutionary history of these endemic taxa and the Caatinga. We estimated a time-calibrated phylogeny for the species group based on two mitochondrial and two nuclear genes and jointly estimated the species limits and species tree within the group. We also devoted a denser phylogeographic sampling of the T. semitaeniatus complex to explore migration patterns, and the spatiotemporal diffusion history to verify a possible role of the São Francisco River as a promoter of differentiation in this saxicolous group of lizards.

Results: Phylogenetic analysis detected high cryptic genetic diversity, occurrence of unique microendemic lineages associated with older highlands, and a speciation history that took place during the Pliocene-Pleistocene transition. Species delimitation detected five evolutionary entities within the T. semitaeniatus species group, albeit with low support. Thus, additional data are needed for a more accurate definition of species limits and interspecific relationships within this group. Spatiotemporal analyses reconstructed the geographic origin of the T. semitaeniatus species complex to be located north of the present-day course of the São Francisco River, followed by dispersal that expanded its distribution towards the northwest and south. Gene flow estimates showed higher migration rates into the lineages located north of the São Francisco River.

Conclusions: The phylogenetic and population structures are intrinsically associated with stable rock surfaces and landscape rearrangements, such as the establishment of drainage basins located to the northern and southern distribution ranges. The T. semitaeniatus complex preserved high genetic diversity during range expansion, possibly as a result of frequent long-distance dispersal events. Our results indicate that both the current course of the São Francisco River and its paleo-courses had an important role in promoting diversification of the Caatinga endemic T. semitaeniatus species group.

Show MeSH
Related in: MedlinePlus