Genetic Structure and Diversity of a Rare Hawaiian Endemic,Lobelia villosa(Campanulaceae: Lobelioideae)

Abstract

Microsatellite markers are valuable tools for determining amount and distribution of genetic diversity and differentiation within and between popu lations. In this study we examined the level of microsatellite variability within and among five populations of Lobelia villosa, a rare Hawaiian endemic lobeliad on the island of Kaua'i. Populations of L. villosa were sampled from two regions on Kaua'i: two populations at the Kilohana Lookout area and three populations from Alaka'i Swamp. Nineteen microsatellite DNA primers were developed for L. villosa, 12 of which demonstrated polymorphism and were subsequently multiplexed and labeled for genotyping. An overall moderate degree of genetic differentiation was found within and between populations. Pairwise FST data showed population structure, and analysis with Structure software indicated two genetic clusters (K = 2) corresponding to the two sampled geographic regions. Although L. villosa exhibits moderate diversity, which exceeds that of other Ha waiian endemics with restricted distributions, measurements of FIS were positive across 10 out of 12 loci, suggesting that inbreeding is occurring at the population level.

Characterization of microsatellite loci in Brighamia insignis and transferability to other genera in the Hawai‘ian lobelioid group

“…Of the 30 primer pairs tested, one did not amplify reliably in either species (locus BRIN59, GenBank accession no. ) and one did not amplify in B. insignis (LOVI52; Tran et al., ). With the remaining primer pairs, one (LOVI4) was monomorphic in both species, three were monomorphic only in B. insignis (BRIN07, BRIN56, and LOVI34), and two were monomorphic only in B. rockii (LOVI90 and LOVI93).…”

“…A total of 28 primer pairs were designed from the libraries, and these amplified products ranging from 100–250 bp. These, and an additional 12 published primers for L. villosa (Tran et al., ), were tested on all samples. To visualize and quantify allele sizes, the forward primer derived from B. insignis libraries was modified with WellRed Black (D2), Green (D3), or Blue (D4) fluorescent dye (Sigma‐Aldrich, St. Louis, Missouri, USA).…”

“…Eighteen microsatellite loci developed in B. insignis and 12 derived from L. villosa (Tran et al., ) were polymorphic and amplified reliably in at least one species. These loci reveal low levels of diversity and high inbreeding in both species, although less so in B. rockii .…”

“…Unfortunately, previous genetic markers used for Brighamia studies have revealed only a limited amount of genetic diversity (Gemmill et al., ; Walsh, ). Here we report 28 microsatellite markers developed for B. insignis and 12 published primers from Lobelia villosa (Rock) H. St. John & Hosaka (Tran et al., ) that were tested on B. insignis and B. rockii , as well as on an additional 13 taxa that represented all six genera in the Hawai‘ian lobelioid group.…”

“…Characteristics of 30 microsatellite loci used for screening in this study, including 18 newly developed markers for Brighamia insignis and 12 previously published markers for Lobelia villosa.Accession numbers are provided for loci developed for Brighamia insignis. Loci for Lobelia villosa were previously published inTran et al (2015).…”