Natural history of the narrow endemics Ipomoea cavalcantei and I. marabaensis from Amazon Canga savannahs

Abstract

Amazon comprises a vast variety of ecosystems, including savannah-like Canga barrens that evolved on iron-lateritic rock plateaus of the Carajás Mountain range. Individual Cangas are enclosed by the rain forest, indicating insular isolation that enables speciation and plant community differentiation. To establish a framework for the research on natural history and conservation management of endemic Canga species, seven chloroplast DNA loci and an ITS2 nuclear DNA locus were used to study natural molecular variation of the red flowered Ipomoea cavalcantei and the lilac flowered I. marabaensis. Partitioning of the nuclear and chloroplast gene alleles strongly suggested that the species share the most recent common ancestor, pointing a new independent event of the red flower origin in the genus. Chloroplast gene allele analysis showed strong genetic differentiation between Canga populations, implying a limited role of seed dispersal in exchange of individuals between Cangas. Closed haplotype network topology indicated a requirement for the paternal inheritance in generation of cytoplasmic genetic variation. Tenfold higher nucleotide diversity in the nuclear ITS2 sequences distinguished I. cavalcantei from I. marabaensis, implying a different pace of evolutionary changes. Thus, Canga ecosystems offer powerful venues for the study of speciation, multitrait adaptation and the origins of genetic variation.

Landscape Genomic Conservation Assessment of a Narrow-Endemic and a Widespread Morning Glory From Amazonian Savannas

“…Although our dataset does not allow disentangling the relative contribution of pollen-movement and seed dispersal to gene flow, wind-mediated seed dispersal is likely to be more restricted, as forest surrounding the montanne savanna highlands constitute natural wind barriers. For instance, a recent work found strong spatial genetic structure when analyzing seven Chloroplast DNA loci in I. cavalcantei (Babiychuk et al, 2017 ), thus suggesting restricted seed dispersal in this species. Additionally, the significant (albeit low) spatial autocorrelation of genotypes found in both species (Figure 3 ) indicates the existence of patches of related individuals from limited seed donors (Davies et al, 2010 ).…”

“…All DNA samples were adjusted to a final concentration of 5 ng/μL in a final volume of 30 μL. We used flow cytometry to estimate genome size in I. maurandioides , as it was already available for I. cavalcantei (Babiychuk et al, 2017 ). Nuclei were obtained from fresh leaf tissues chopped in general purpose buffer with 1% Triton X-100 and 1% PVP-30 (Loureiro et al, 2007 ).…”

Geography is essential for reproductive isolation between florally diversified morning glory species from Amazon canga savannahs

“…Firstly, canga evolved on iron laterite rock outcrops found at some isolated mountain tops in Carajás mountain range at the similar elevations of ca. 700 m above sea level; are surrounded by a very dense mountainous rain forest, the canopy of which towers at 10–20 meters, and are often separated by the ravines in the eroding mountainous landscape, indicative of the insular type geographic isolation 62 (Supplementary Fig. S1).…”

PIPEBAR and OverlapPER: tools for a fast and accurate DNA barcoding analysis and paired-end assembly

“…DNA barcoding is an important molecular methodology based in a short standardized polymorphic sequence capable of distinguishing species. This approach is widely employed in biodiversity studies to identify and classify the diversity of well-known species or unexplored groups [ 4 – 6 ], evaluate inter- and intra-species variations [ 6 – 8 ], detect cryptic species or join genetically similar but morphologically distinct species [ 5 , 7 – 9 ]. Also, DNA barcoding has been proposed for forensic identification and development of DNA reference library, since the lack of a reliable DNA barcoding reference library is the main barrier to its application [ 2 ] Sanger technology has been widely used for aiding morphological species identification because is a useful tool for identifying genetically distinct units worthy of more intense taxonomic study [ 3 , 7 – 9 ] and creation of reference database, such as BOLD [ 10 ].…”

“…Also, DNA barcoding has been proposed for forensic identification and development of DNA reference library, since the lack of a reliable DNA barcoding reference library is the main barrier to its application [ 2 ] Sanger technology has been widely used for aiding morphological species identification because is a useful tool for identifying genetically distinct units worthy of more intense taxonomic study [ 3 , 7 – 9 ] and creation of reference database, such as BOLD [ 10 ]. In these cases, there are necessity of sequencing of individual specimens using genome regions in order to infer evolutionary differences and identification only [ 5 ].…”