Genetic diversity and population structure of naturally rare Calibrachoa species with small distribution in southern Brazil

Abstract

Calibrachoa is a South-American genus comprising 27 species, several considered endemic or rare; few were subjects in genetic studies. We attempted to generate new data about the phylogenetically related and rare species C. eglandulata, C. sendtneriana, C. serrulata, and C. spathulata concerning their genetic diversity and population structure, which, coupled with their known restricted distribution, could help access their conservation status and contribute to the study of the Brazilian biodiversity. We sequenced 88 individuals for plastid intergenic spacers and genotyped 186 individuals for five microsatellite loci. Compared among each other, C. sendtneriana and C. serrulata presented the highest values of genetic diversity [π% (sd) = 0.23 (0.14) and 0.43 (0.25), respectively], followed by C. spathulata [π% (sd) = 0.19 (0.12)] and C. eglandulata [π% (sd) = 0.02 (0.03)]. Population differentiation was evident for these latter species, whereas it was not significant for C. sendtneriana and C. serrulata. Factors such as habitat specificity and fragmentation, pollination syndrome, and life history could explain the observed patterns. Based on the new genetic data and the species’ biology, a conservation status was assigned for C. sendtneriana and the status of the other three species was reviewed.

How diverse can rare species be on the margins of genera distribution?

“…Calibrachoa elegans presented even lower genetic diversity indices compared to other Calibrachoa species as well as P. mantiqueirensis . The four micro-endemic highland species, C. eglandulata , C. sendtneriana , C. serrulata and C. spathulata , which have population sizes and geographical ranges similar to C. elegans , possess greater genetic diversity indices for both plastid and nuclear markers (John et al 2019), whereas based on plastid diversity, the widespread species C. sellowiana (π = 0.088 %; J. N. Fregonezi et al ., unpubl. data) and C. heterophylla (π = 0.41 %; Mäder et al 2013) also have greater genetic diversity than C. elegans.…”

Genetic diversity in Calibrachoa pygmaea (Solanaceae): A hawkmoth-pollinated nightshade from the Pampas

“…In this work, we showed the highest component of genetic diversity of C. pygmaea is within populations based on both marker types, as seen through AMOVA results. This species possesses high genetic variability compared to other Calibrachoa species (i.e., John et al 2019), as observed by the number and haplotype diversity, as well as the nuclear marker diversity indices, despite also displaying elevated levels of inbreeding -suggested by the high and significant FIS values. Clearly dependent on pollinators, this species' genetic structure and diversity may be affected by crossings between related individuals more than gene flow between populations.…”

Evaluation of the genetic variability of Ophrys insectifera L. populations growing in Belarus using molecular iPBS markers

“…Генетически однородные популяции более подвержены влиянию биотических и абиотических факторов и могут элиминироваться в результате распространения болезней и патогенов, а популяции с более узким диапазоном генотипов могут исчезать при экстремальных климатических условиях, таких как жара, холод, засуха и т. д. [4,14].…”