The potential implications of rainforest history, hybridization, and climate change on the phylogenetics of a rare genus of herbsRomnalda(Dasypogonaceae) from New Guinea and Australia

Abstract

There are many genera shared between Australian and Papua New Guinean rainforests. Species in the rare rainforest herbaceous genus Romnalda have a relictual and disjunct distribution within the major rainforest blocs of southern Queensland, north Queensland, and New Guinea. There are only four species in this genus: R. strobilacea, R. grallata, and R. sp.‘Cooper Ck’ from Australia, and R. papuana from New Guinea. The Australian species have restricted distributions and high conservation status. Allozymes were used to study the genetic variation and distinctiveness of all four species. Genetic diversity varied significantly amongst the four species. The species in the centre of the genus distribution contained the highest genetic diversity, regardless of rarity. The undescribed R. sp.‘Cooper Ck’ was identified as a clearly distinct species with morphological affinities to R. papuana, but genetic affinities to R. grallata. The study showed that, where the distributions of R. grallata and R. sp.‘Cooper Ck’ overlapped, there was evidence of hybridization. Reproductive participation within populations was typically low with limited flowering synchrony. Populations of all four species were inbred, but higher levels of inbreeding were not correlated with lower genetic diversity. The timing of flowering appeared to be determined by climate. Altitudinal variation in phenological timing in R. sp.‘Cooper Ck’ has led to genetic isolation within the species, but has also limited its genetic introgression with the co‐occurring R. grallata. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 157, 455–474.

Fragmentation and Genetic Diversity in Romnalda (Dasypogonaceae), a Rare Rain forest Herbaceous Genus from New Guinea and Australia

“…Levels of genetic diversity in all species in the genus Romnalda were quite high compared with endemic, rain forest, or herbaceous species (Hamrick & Godt 1989, Shapcott 2000, Honnay et al 2005, Shapcott et al . 2008).…”

“…Little is known of the biology or ecology of Romnalda , however, they are superficially similar (Shapcott et al . 2008).…”

“…2008). All four Romnalda species occur as small, discrete, populations, apparently restricted to undisturbed subtropical or tropical rain forest in mostly upland and highly significant refugial rain forest areas, indicating that current species distributions may be largely relictual (Webb & Tracey 1981, Shapcott et al . 2008).…”

“…2008). All are small herbaceous perennials growing to ca 50 cm tall, with strap‐like leaves and some vegetative spread achieved by budding from prop roots (Henderson 1986, Shapcott et al . 2008).…”

Habitat fragmentation decreased the genetic variability of Trichilia elegans A. Juss. (Meliaceae) in southern Brazil

“…In these sense, the habitat fragmentation and the creation of so-called edge effects may have several implications on fauna and flora, which varies according to life histories and regeneration modes (SUGIYAMA and PETER- SON, 2013). The genetic implications may be complex (RIVERO-GUERRA, 2008;SHAPCOTT et al, 2008;ANDRADE et al, 2009), including rare alleles loss, increased inbreeding (VRANCKX et al, 2012) and reduced reproductive fitness (FINGER et al, 2011), leading to genetic differentiation in subpopulations created by fragmentation (FINGER et al, 2012).…”