Leapfrogging into new territory: How Mascarene ridged frogs diversified across Africa and Madagascar to maintain their ecological niche.
The Mascarene ridged frog, Ptychadena mascareniensis, is a species complex that includes numerous lineages occurring mostly in humid savannas and open forests of mainland Africa, Madagascar, the Seychelles, and the Mascarene Islands. Sampling across this broad distribution presents an opportunity to examine the genetic differentiation within this complex and to investigate how the evolution of bioclimatic niches may have shaped current biogeographic patterns. Using model-based phylogenetic methods and molecular-clock dating, we constructed a time-calibrated molecular phylogenetic hypothesis for the group based on mitochondrial 16S rRNA and cytochrome b (cytb) genes and the nuclear RAG1 gene from 173 individuals. Haplotype networks were reconstructed and species boundaries were investigated using three species-delimitation approaches: Bayesian generalized mixed Yule-coalescent model (bGMYC), the Poisson Tree Process model (PTP) and a cluster algorithm (SpeciesIdentifier). Estimates of similarity in bioclimatic niche were calculated from species-distribution models (maxent) and multivariate statistics (Principal Component Analysis, Discriminant Function Analysis). Ancestral-area reconstructions were performed on the phylogeny using probabilistic approaches implemented in BioGeoBEARS. We detected high levels of genetic differentiation yielding ten distinct lineages or operational taxonomic units, and Central Africa was found to be a diversity hotspot for these frogs. Most speciation events took place throughout the Miocene, including "out-of-Africa" overseas dispersal events to Madagascar in the East and to São Tomé in the West. Bioclimatic niche was remarkably well conserved, with most species tolerating similar temperature and rainfall conditions common to the Central African region. The P. mascareniensis complex provides insights into how bioclimatic niche shaped the current biogeographic patterns with niche conservatism being exhibited by the Central African radiation and niche divergence shaping populations in West Africa and Madagascar. Central Africa, including the Albertine Rift region, has been an important center of diversification for this species complex.
Museum of Comparative Zoology, Harvard University, Cambridge, MA 02138, USA. Electronic address: bzimkus@oeb.harvard.edu.
Breda M
BM
Zimkus
Department of Biological Sciences, University of Cincinnati, 820F Rieveschl Hall, Cincinnati, OH 45221, USA. Electronic address: lucinda.lawson@uc.edu.
Lucinda P
LP
Lawson
Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Invalidenstrasse 43, 10115 Berlin, Germany. Electronic address: MichaelF.Barej@mfn-berlin.de.
Michael F
MF
Barej
University of Basel, Biogeography Research Group, Department of Environmental Sciences, Klingelbergstrasse 27, Basel 4056, Switzerland. Electronic address: c.d.barratt@gmail.com.
Christopher D
CD
Barratt
University of the Western Cape, Biodiversity and Conservation Biology, Private Bag X17, Bellville 7535, South Africa. Electronic address: achanning@uwc.ac.za.
Alan
A
Channing
Department of Biological Sciences, University of Texas at El Paso, 500 W. University Ave., El Paso, TX 79968, USA; Department of Biology, Tidewater Community College, 120 Campus Dr., Portsmouth, VA 23701, USA. Electronic address: kmweber@miners.utep.edu.
Katrina M
KM
Dash
Institute of Integrated Sciences, Department of Biology, University of Koblenz-Landau, Universitätsstraße 1, 56070 Koblenz, Germany. Electronic address: dehling@uni-koblenz.de.
J Maximilian
JM
Dehling
African Amphibian Conservation Research Group, Unit for Environmental Sciences and Management, North-West University, Potchefstroom 2520, South Africa; South African Institute for Aquatic Biodiversity, Somerset Street, Grahamstown 6139, South Africa. Electronic address: Louis.DuPreez@nwu.ac.za.
Louis
L
Du Preez
Fakultät für Biologie Universität Bielefeld, Abt. Biologiedidaktik, Universitätsstraße 25, 33615 Bielefeld, Germany. Electronic address: SebastianGehring@web.de.
Philip-Sebastian
PS
Gehring
Department of Biological Sciences, University of Texas at El Paso, 500 W. University Ave., El Paso, TX 79968, USA. Electronic address: egreenbaum2@utep.edu.
Eli
E
Greenbaum
Institute of Vertebrate Biology, Czech Academy of Sciences, 603 65 Brno, Czech Republic; National Museum, Department of Zoology, 19300 Prague, Czech Republic. Electronic address: vaclav.gvozdik@ivb.cz.
Václav
V
Gvoždík
Harvey Ecological, 35 Carbis Road, Pietermaritzburg 3201, KwaZulu-Natal, South Africa. Electronic address: info@harveyecological.co.za.
James
J
Harvey
Department of Biology, University of Copenhagen, Copenhagen, Denmark. Electronic address: joskielgast@hotmail.com.
Jos
J
Kielgast
Centre de Recherche en Sciences Naturelles, Département de Biologie, Lwiro, The Democratic Republic of the Congo. Electronic address: chifkusamba@gmail.com.
Chifundera
C
Kusamba
Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Invalidenstrasse 43, 10115 Berlin, Germany; Joint Experimental Molecular Unit, Royal Belgian Institute of Natural Sciences, Rue Vautier 29, 1000 Brussels, Belgium. Electronic address: ztnagy@naturalsciences.be.
Zoltán T
ZT
Nagy
Department of Comparative Anatomy, Institute of Zoology, Jagiellonian University, Gronostajowa 9, 30-387 Kraków, Poland. Electronic address: maciej.pabijan@uj.edu.pl.
Maciej
M
Pabijan
Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Invalidenstrasse 43, 10115 Berlin, Germany; Wildlife Ecology & Management, University of Freiburg, Tennenbacher Str. 4, 79106 Freiburg, Germany. Electronic address: johannes.penner@mfn-berlin.de.
Johannes
J
Penner
Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Invalidenstrasse 43, 10115 Berlin, Germany. Electronic address: mo.roedel@mfn-berlin.de.
Mark-Oliver
MO
Rödel
Division of Evolutionary Biology, Zoological Institute, Technical University of Braunschweig, Mendelssohnstraße. 4, 38106 Braunschweig, Germany. Electronic address: m.vences@tu-braunschweig.de.
Miguel
M
Vences
Trier University, Department of Biogeography, 54286 Trier, Germany. Electronic address: loetters@uni-trier.de.
Stefan
S
Lötters
D000349:Africa; D000818:Animals; D001499:Bayes Theorem; D045303:Cytochromes b / Q000145:classification / Q000235:genetics / Q000378:metabolism; D004247:DNA / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D004463:Ecology; D006239:Haplotypes; D018398:Homeodomain Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism; D008270:Madagascar; D010802:Phylogeny; D058974:Phylogeography; D025341:Principal Component Analysis; D012336:RNA, Ribosomal, 16S / Q000145:classification / Q000235:genetics / Q000378:metabolism; D011898:Ranidae / Q000145:classification* / Q000235:genetics; D017422:Sequence Analysis, DNA
D018398:Homeodomain Proteins; D012336:RNA, Ribosomal, 16S; D004247:DNA; D045303:Cytochromes b
Amphibia; Historical biogeography; Pan-African; Phylogeny; Ptychadena; Species delimitation; Species distribution modeling