Population genetic structure of Sisyrinchium micranthum Cav. (Iridaceae) in Itapuã State Park, Southern Brazil

Abstract

Sisyrinchium micranthum Cav. is a member of the family Iridaceae, which is distributed over the American continent. In Brazil, this species is found, not only in disturbed areas and coastal regions, but is also very common in urban centers, such as public parks, during the spring. Chromosome counts for North American specimens are 2n = 32 and 2n = 48, whereas in southern Brazil, there is a polyploidy series with three chromosome numbers, 2n = 16, 2n = 32, and 2n = 48. Population analyses using DNA molecular markers are inexistent for this species, in spite of its wide distribution and morphological variation. To study the genetic population structure of S. micranthum, five natural populations were accessed in a conservation park within the Atlantic Rain Forest Biome in southern Brazil. Here, the chromosome numbers 2n = 16 and 2n = 48 had already been described. Molecular analysis showed that the populations are highly structured with low gene flow among them. The population with 2n = 48 was genetically less variable than and distinct from the other populations. Population genetics in relation to cytogenetic data provided new insights regarding the genetic diversification and mating system of S. micranthum.

Differentiation between two self-compatible cytotypes of Herbertia lahue (Iridaceae): evidence from genotypic and phenotypic variation

“…The variance found among populations when the whole dataset was considered supported genetic differentiation between cytotypes (Table 5), despite the moderate variation highlighted when cytotypes were partitioned by the analysis. Strong differentiation among populations appears to be common in Iridaceae, which is congruent with previous studies (Artyukova et al 2001;Arafeh et al 2002;Wróblewska et al 2003;Saad and Mahy 2009;Tacuatiá et al 2012a) and suggests that the limited capacity of seed dispersal could encourage further genetic differentiation (Arafeh et al 2002). Indeed, the combined effect of selfing and poor seed dispersal ability could contribute to isolation among populations, subsequently resulting in genetic Fig.…”

“…With respect to previous studies of other Iridaceae species, results from this study revealed low levels of genetic variation in populations for H. lahue when compared to: Iris setosa Pall. ex Link (Artyukova et al 2001 (Tacuatiá et al 2012a). Outcrossing is the predominant breeding system in these species, which may be one reason for higher levels of genetic variation in comparison with H. lahue, which is congruent with the suggestion that outcrossing species exhibit larger diversity index values than selfing species (Hamrick and Godt 1996;Nybom 2004).…”

Diversity and genetic structure of the husk tomato (Physalis philadelphica Lam.) in Western Mexico

“…4 Hierarchical organization of genetic relatedness of nine Physalis philadelphica populations, analyzed by STRUCTURE software (Pritchard et al 2000). The optimal clustering number (K = 2) was determined based on the ad hoc statistic DK following Evanno et al (2005) using the Harvester program (Earl and vonHoltd 2012) Sisyrinchium micranthum (He = 0.240, p = 69 %, Tacuatia et al 2012), two species with habits and reproductive systems similar to those of P. philadelphica. Generally, genetic diversity is expected to decrease with increased intensity of plant population management (Doebley et al 2006;Ladizinsky 1998).…”

O Estudo Da Biodiversidade E Evolução Vegetal Através De Marcadores De Dna E Citogenética: Exemplos Em Iridaceae E Poaceae

“…Uma característica importante para a família é a extensa variação morfológica vista em alguns grupos, o que torna os relacionamentos internos complexos. Assim, marcadores moleculares têm sido utilizados com sucesso tanto para a caracterização molecular de cultivares e de espécies (CAIOLA, CAPUTO & ZANIER, 2004;DE MARCO et al, 2009;MORAGA et al, 2010;RANJAN et al, 2010;TACUATIÁ et al, 2012b), quanto para a obtenção de estimativas de parâmetros de genética de populações (HANNAN & ORICK, 2000;WRÓBLEWSKA et al, 2003;DE MARCO et al, 2009;TACUATIÁ et al, 2012a), ou mesmo, para auxiliar na investigação de mecanismos envolvidos na especiação, correlacionando com informações ecológicas (RYMER et al, 2010). O mérito desses estudos foi esclarecer a complexidade evolutiva de alguns grupos de Iridaceae, evidenciando que a citogenética e a biologia da polinização foram fundamentais para a diversificação e para a adaptação de novidades evolutivas surgidas na família.…”

“…Outras espécies de Herbertia que pos-suem algum tipo de barreira à autogamia, apresentaram estimativas de diversidade genética intrapopulacional altas, coerentes com o esperado para espécies autoincompatíveis (Stiehl-Alves et al, in prep.). De um modo geral, nós observamos que as populações são bastante diferenciadas geneticamente, algo já evidenciado em outros estudos em Iridaceae (HANNAN & ORICK, 2000;WRÓBLEWSKA et al, 2003;DE MARCO et al, 2009;RYMER et al, 2010;TACUATIÁ et al, 2012a). Possivelmente, o sistema de dispersão de sementes tem forte impacto na diferenciação genética de populações de Iridaceae, visto que, caracteristicamente, a barocoria permite que as sementes sejam alocadas por distâncias restritas intra-populacionalmente.…”