Natural colonization or introduction? Phylogeographical relationships and morphological differentiation of house geckos (Hemidactylus) from Madagascar

Several house gecko species of the genus Hemidactylus are almost cosmopolitan lizards, with distributions that have probably been shaped by natural transoceanic dispersal as well as by more recent human introductions. Here we revise the Hemidactylus populations of Madagascar and compare them genetically with populations from other sites in the Indian Ocean region. Morphological data strongly confirm the occurrence of three Hemidactylus species on Madagascar: Hemidactylus frenatus , distributed along the western coast of Madagascar; H. platycephalus , restricted to the north-west and the widespread H. mercatorius that occurs throughout the island, including coastal areas at sea level as well as big cities (Antananarivo, Fianarantsoa) at altitudes of 1200–1300 m above sea level. Analyses of partial sequences of the 16S rRNA gene in 46 Hemidactylus specimens from Madagascar, East Africa, South Asia, and the Comoro and Mascarene archipelagos demonstrated the presence of a fourth species, H. brooki, on the Mascarenes (Réunion, Rodrigues, and Mauritius) and Comoros (Moheli). The Malagasy populations of H. platycephalus were genetically uniform and differentiated from the African and Comoroan specimens studied. H. frenatus had a relatively low genetic differentiation over the whole region with no recognizable phylogeographical structure, indicating more recent colonizations or introductions. In contrast, H. mercatorius showed a strong phylogeographical structure of haplotypes, with two distinctly different lineages in Madagascar. Moreover, all Malagasy specimens differed strongly from the single African specimen included. This indicates that populations of H. mercatorius in Madagascar have a long history that predates human settlement.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 83 , 115–130.     

Response to Phosphate Deficiency in Bean (Phaseolus vulgarisL.) Roots. Respiratory Metabolism, Sugar Localization and Changes in Ultrastructure of Bean Root Cells

Bean plants (Phaseolus vulgarisL. ‘Zlota Saxa’)were cultured on complete (+P) or phosphate-deficient (-P) nutrientmedium. A large increase in glucose concentration was foundin the meristematic zone of -P roots compared to control roots.The increased glucose concentration in the meristematic zonedid not influence total respiration rate. Glucose or uncoupler(carbonyl cyanide m-chlorophenylhydrazone) failed to increasethe respiration rate in -P root segments, but stimulated respirationin +P roots. The ultrastructure of cortical cells from the meristematicroot zone showed marked differences between +P and -P plants.Large vacuoles, invaginations of the plasmalemma and condensedforms of mitochondria were dominating features in cortical cellsof -P roots. Analysis of extracts after treating roots withdimethylsulfoxide (DMSO) indicated different localization ofsugars in the cell compartments. In roots of -P plants, mostof the reducing sugars were detected in the cytoplasm fractionwhile most sucrose was in the vacuole. Observations of the effectof 10% DMSO on cell ultrastructure indicated partial destructionof the plasmalemma but not the tonoplast. The localization ofreducing sugars in secondary vacuoles or plasmalemma invaginationsin the cells from the meristematic region of -P roots is discussed.Copyright1998 Annals of Botany Company. Bean (Phaseolus vulgarisL.), roots, Pi deficiency, respiration, meristematic zone, ultrastructure, sugar efflux, reducing sugars and sucrose localization.     

Universal primers for a large cryptically simple cpDNA microsatellite region in Aristolochia (Aristolochiaceae)

We provide a new and valuable marker to study species relationships and population genetics in order to trace evolutionary, ecological, and conservational aspects in the genus Aristolochia. Universal primers for amplification and subsequent sequencing of a chloroplast microsatellite locus inside the trnK intron are presented. Utility of the primers has been tested in 32 species representing all clades of Aristolochia, including population studies within the A. pallida complex, A. clusii and A. rotunda. The microsatellite region is characterized as a (A_nT_m)_k repeat of 22–438 bp containing a combination of different repeats arranged as ‘cryptically simple’.