A multidisciplinary approach to inform assisted migration of the restricted rainforest tree, Fontainea rostrata

Abstract

Assisted migration can aid in the conservation of narrowly endemic species affected by habitat loss, fragmentation and climate change. Here, we employ a multidisciplinary approach by examining the population genetic structure of a threatened, dioecious rainforest tree of the subtropical notophyll vine forests of eastern Australia, Fontainea rostrata, and its potential requirements for population enhancement and translocation to withstand the effects of anthropogenic fragmentation and climate change. We used microsatellite markers to gain an understanding of the way genetic diversity is partitioned within and among the nine extant populations of F. rostrata identified in this study. We combined the results with species distribution modelling to identify populations vulnerable to possible future range shifts based on climate change projections. We found regional differences between the species’ main distribution in the south and a disjunct northern population cluster (FRT = 0.074, FSR = 0.088, FST = 0.155), in mean allelic richness (AR = 2.77 vs 2.33, p < 0.05), expected heterozygosity (HE = 0.376 vs 0.328), and inbreeding (F = 0.116 vs 0.219). Species distribution models predicted that while southern populations of F. rostrata are likely to persist for the next 50 years under the RCP6.0 climate change scenario, with potential for a small-scale expansion to the south-east, the more highly inbred and less genetically diverse northern populations will come under increasing pressure to expand southwards as habitat suitability declines. Given the species’ genetic structure and with the aim to enhance genetic diversity and maximise the likelihood of reproductive success, we recommend that plant reintroductions to supplement existing populations should be prioritised over translocation of the species to new sites. However, future conservation efforts should be directed at translocation to establish new sites to increase population connectivity, focussing particularly on habitat areas identified as persisting under conditions of climate change.

Phylogenetic Reconstruction of the Rainforest Lineage Fontainea Heckel (Euphorbiaceae) Based on Chloroplast DNA Sequences and Reduced-Representation SNP Markers

“…This is a key area of the ecology of the genus that would benefit from further attention. However, pollen dispersal of F. picrosperma has a limited range of 30 m [16], and we therefore anticipate that similar pollen-flow dynamics between other isolated Fontainea populations could limit gene flow and increase genetic structuring and drift. Finally, our phylogenetic reconstructions have presented valuable knowledge of the genetic relationships of Fontainea and have also raised some important considerations regarding the taxonomical hierarchy between some species.…”

“…With the emergence of new molecular tools for assessing phylogenetic relationships, it is valuable to revisit the current traditional classifications, especially to ensure effective conservation management of threatened species. Recently, there have been several species-specific population genetic and floral biology studies, of the Australian Fontainea species [15][16][17][18][19], with one study [17] indicating the species boundaries of two threatened taxa (F. australis and F. oraria) need further attention. Rossetto [17] highlighted some populations of F. australis were genetically different from other populations and did not cluster with morphologically similar F. oraria.…”

Integrating Phylogeographic Analysis and Geospatial Methods to Infer Historical Dispersal Routes and Glacial Refugia of Liriodendron chinense

“…In recent years, landscape genetics have been increasing in popularity and developing, and improvements in molecular genetics tools, combined with existing or new statistical methods (Geo-statistics, Bayesian approaches, and maximum likelihood) and powerful computers, have achieved better results by combining genetic and geospatial data [36][37][38]. The aim of such techniques is to link landscape features and biological microevolutionary processes, such as gene flow, genetic drift, and adaptive evolution [39].…”

The geno-geo-climate nexus: contributions of geographic and ecological factors in shaping the genomic divergence of two closely related threatened rainforest species of Fontainea Heckel (Euphorbiaceae)

“…Although both ex-situ and in-situ Coastal Fontainea populations have been established for conservation purposes, there is an opportunity to re ne management objectives that include adaptive potential outlined in this study. Equipped with the information from this research and previous studies (Rossetto et al, 2000, Brunton et al, 2022, we advocate for immediate action to preserve Southern Fontainea populations, using a similar strategy proposed for F. rostrata or, Deep Creek Fontainea (Conroy et al, 2019) to ensure the long-term survival of both species. Speci cally, for longstanding conservation of both Fontainea species, assisted migration of populations to suitable habitats may be necessary but should consider the genetic composition, adaptation potential and local environment conditions of each population.…”

“…With just 10 mature individuals, it is considered at-risk of extinction which has prompted in-situ and ex-situ conservation management to enhance the long-term survival of the species (Rossetto et al, 2000). Little is known about the dispersal syndromes for Fontainea, however gravity and hydrochory are likely key vectors for the transport of diaspores (Conroy et al, 2019, Lamont et al, 2016. Reproductive biology of F. picrosperma, form far-north QLD showed pollen-mediated gene ow of is generally limited to short distances of ~ 30 m. Since all Fontainea species share similar reproductive traits, we may expect that pollen movement events for Southern and Coastal Fontainea are also spatially restricted.…”