Mangrove forests are distributed in the intertidal zones of tropical and subtropical regions, and have been severely damaged by anthropogenic activities, climate change, and stochastic events. Although much progress has been made in the conservation and restoration of mangroves in China, studies of the genetic diversity of mangroves are lacking, especially for isolated populations, yet such studies are essential for guiding conservation and restoration efforts. Here, we evaluated the genetic diversity, spatial genetic structure, and mating system of two mangrove species, Rhizophora apiculata and Avicennia marina, in a heavily disturbed area in Tielu Harbor, Sanya City, Hainan Island, China, using 18 nuclear microsatellite markers. We found that the genetic diversity of R. apiculata, which is classified as ‘Vulnerable’ in the China Red List categories, was high and similar compared with the genetic diversity estimates of other populations reported in previous studies. In contrast, the genetic diversity of A. marina, which is classified as a species of ‘Least Concern’, was low compared with the genetic diversity estimates of other populations. We then evaluated the presence of genetic bottlenecks, spatial genetic structure, and the mating system to determine the effects that habitat destruction has had on these two species. Our findings indicate that distinct conservation and restoration approaches are needed for these two species. Generally, our results provide valuable information that will aid the development of conservation and restoration strategies for the mangroves of Tielu Harbor.

The distribution of species changes over time, and the current distribution of different species could result from distinct eco-evolutionary processes. Thus, investigating the spatiotemporal changes in the niche and geographic range of species is fundamental to understanding those processes and mechanisms shaping the current distributions of species. However, many studies only compared the current distribution and niche of the target species, ignoring the fact that the range shift of species is a dynamic process. Here, we reconstructed niche evolution and range dynamics of species to provide more information on related eco-evolutionary processes. We focused on a monophyletic species complex,Chrysanthemum zawadskiispecies complex, in which species occupy diverse habitats and exhibit different distribution patterns. Specifically, we investigated the niche breadth and overlap between lineages or species of the complex in geographic and environmental spaces. We then tested the phylogenetic signals for different climatic variables and estimated the niche of ancestral nodes on a time-calibrated phylogeny. Next, we used phyloclimatic modeling to reconstruct the dynamics of range shift for this complex. Our results show that this complex contains both specialist and generalist species, and niche diverges greatly among different species and intraspecific lineages of the complex. The moisture gradient may be the primary driver of the niche divergence of species in the complex. The reconstruction of ancestral distribution shows that this complex originated in the Qinling mountains and surrounding areas during the early Pliocene, and then diverged with the range expansion and niche evolution. Species of the complex have different range dynamics. Based on our findings, we propose that niche evolution, range dynamics, and their coupling shape the distribution of species, which provides insight into the eco-evolutionary processes that formed the current distribution of species in theC. zawadskiicomplex.

Background and Aims: Competition with sympatric diploid progenitor(s) hinders the persistence of polyploids. The hypothesis that polyploids escape from competition through niche shifts has been widely tested; however, niche escape is unlikely to completely avoid competition. Given species growing in less favourable environments probably have weaker competitive abilities, we hypothesize that polyploid populations tend to persist in areas where their progenitors have relatively low habitat suitability. Methods: This study investigated two sibling allopolyploid species, Achillea alpina and A. wilsoniana of the daisy family, which originated independently from the same two parental species. We explored the patterns of niche shifts between the polyploids and their progenitors by using several ecoinformatics analyses in environmental and geographical spaces, and performed ecological niche modelling to estimate the historical distribution of these species as well as the potential regions for persistence of allopolyploids. Key Results: The niche shift patterns of the two polyploids were not completely consistent: A. alpina showed niche expansion, while A. wilsoniana exhibited a trend towards niche novelty. Their potential suitable areas were both more likely to overlap with regions where the habitat suitability values of their parental species became low. Conclusions: The present results support our hypothesis that populations of polyploids tend to persist in areas that are less suitable for their diploid progenitors. Meanwhile, niche shifts may promote the success of polyploids. These findings contribute to our understanding of the ecological processes involved in the maintenance and persistence of polyploids.