ORCID Profile
0000-0003-4690-4593
Current Organisation
University of Tasmania School of Plant Science
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Publisher: Frontiers Media SA
Date: 17-07-2018
Publisher: Frontiers Media SA
Date: 02-12-2019
Publisher: Wiley
Date: 05-06-2021
DOI: 10.1111/JBI.14148
Abstract: The centre‐periphery hypothesis (CPH) states that peripheral populations exhibit lower genetic ersity, abundance and size, and higher differentiation compared to central populations, due to a decline in environmental suitability towards range margins. Here, we tested if neutral genetic ersity and functional leaf trait ersity fit the predicted patterns of the CPH. Cerrado, Brazil. Qualea grandiflora (Vochysiaceae) and Annona crassiflora (Annonaceae). Variation in eight functional leaf traits and nine or eight microsatellite loci were analysed in 37 populations (777 in iduals) of Q . grandiflora and 21 populations (397 in iduals) of A . crassiflora . We tested CPH using three distinct centres of species’ range: geographical (centre of species’ geographic occurrence), historical (centre of species’ refugia) and ecological (centre of species’ current suitability areas). Generalised linear regressions were performed between genetic ersity and differentiation, coefficients of variation and means of leaf metamer traits of populations and their distances from each centre. A decrease in allele richness was observed from central towards peripheral populations for ecological (both species) and geographical centres ( Q . grandiflora ). Overall, the results for both species pointed to a decrease in metamer vigour towards marginal populations, pattern consistent with a decrease in environmental suitability towards periphery as predicted by CPH. Besides geographical and ecological centres, leaf traits fitted CPH considering historical centre. Results for leaf traits and genetic ersity of two phylogenetically distant species indicate the consistency of the CPH for Cerrado species. Our results highlight the importance of considering distinct centres and a great number of populations along species’ range to better determinate the processes underlying the distribution of genetic ersity and functional traits. The low genetic ersity and metamer vigour in marginal populations can explain the Cerrado endemism of studied species and suggest that the ongoing climatic changes can be critical for their survival.
Publisher: Cambridge University Press (CUP)
Date: 29-11-2016
DOI: 10.1017/S0031182016002134
Abstract: To evaluate the distribution of asymptomatic infection by Leishmania infantum in a metropolis in Brazil with different relative risks (RRs) for disease and risk factors associated with the infection, an ecological study was conducted using a Bayesian approach to estimate the RR of human visceral leishmaniasis (HVL) based on cases between 2008 and 2011. The areas were categorized and selected according to disease incidence: low (area-1), medium (area-2) and high (area-3). Cross-sectional study enrolling 935 children was used to estimate the prevalence of infection by L. infantum . Volunteers from these three areas were tested for L. infantum infection by ELISA (rK39 and soluble antigens). Infection prevalence rates were estimated and compared with the RR of disease. Multilevel logistic regression model evaluated the relationship between infection and the analysed variables. The RR of HVL was distributed heterogeneously in the municipality. The infection prevalence rates were: 34·9% in area-1 29·3% in area-2 and 33·6% in area-3, with no significant differences between these areas. The variables ‘Presence of backyards in the neighbourhood’ and ‘Younger children’ were associated with L. infantum infection. We conclude that infection by L. infantum affects a significant proportion of the infant population regardless of the RR of disease.
Publisher: Wiley
Date: 27-02-2023
DOI: 10.1111/MEC.16892
Abstract: In plants where seed dispersal is limited compared with pollen dispersal, hybridisation may enhance gene exchange and species dispersal. We provide genetic evidence of hybridisation contributing to the expansion of the rare Eucalyptus risdonii into the range of the widespread Eucalyptus amygdalina . These closely related tree species are morphologically distinct, and observations suggest that natural hybrids occur along their distribution boundaries and as isolated trees or in small patches within the range of E. amygdalina . Hybrid phenotypes occur outside the range of normal dispersal for E. risdonii seed, yet in some hybrid patches small in iduals resembling E. risdonii occur and are hypothesised to be a result of backcrossing. Using 3362 genome‐wide SNPs assessed from 97 in iduals of E. risdonii and E. amygdalina and 171 hybrid trees, we show that (i) isolated hybrids match the genotypes expected of F 1 /F 2 hybrids, (ii) there is a continuum in the genetic composition among the isolated hybrid patches from patches dominated by F 1 /F 2 ‐like genotypes to those dominated by E. risdonii ‐backcross genotypes, and (iii) the E. risdonii ‐like phenotypes in the isolated hybrid patches are most‐closely related to proximal larger hybrids. These results suggest that the E. risdonii phenotype has been resurrected in isolated hybrid patches established from pollen dispersal, providing the first steps in its invasion of suitable habitat by long‐distance pollen dispersal and complete introgressive displacement of E. amygdalina . Such expansion accords with the population demographics, common garden performance data, and climate modelling which favours E. risdonii and highlights a role of interspecific hybridisation in climate change adaptation and species expansion.
Publisher: Oxford University Press (OUP)
Date: 05-08-2021
DOI: 10.1093/AOB/MCAB103
Abstract: Hybridization is increasingly recognized as an integral part of the dynamics of species range expansion and contraction. Thus, it is important to understand the reproductive barriers between co-occurring species. Extending previous studies that argued that the rare Eucalyptus risdonii was expanding into the range of the surrounding E. amygdalina by both seed and pollen dispersal, we here investigate the long-term fitness of both species and their hybrids and whether expansion is continuing. We assessed the survival of phenotypes representing a continuum between the two pure species in a natural hybrid swarm after 29 years, along with seedling recruitment. The performance of pure species as well as of artificial and natural hybrids was also assessed over 28 years in a common garden trial. In the hybrid zone, E. amygdalina adults showed greater mortality than E. risdonii, and the current seedling cohort is still dominated by E. risdonii phenotypes. Morphologically intermediate in iduals appeared to be the least fit. Similar results were observed after growing artificial first-generation and natural hybrids alongside pure species families in a common garden trial. Here, the survival, reproduction, health and growth of the intermediate hybrids were significantly less than those of either pure species, consistent with hybrid inferiority, although this did not manifest until later reproductive ages. Among the variable progeny of natural intermediate hybrids, the most E. risdonii-like phenotypes were the most fit. This study contributes to the increasing number of reports of hybrid inferiority in Eucalyptus, suggesting that post-zygotic barriers contribute to the maintenance of species integrity even between closely related species. However, with fitness rapidly recovered following backcrossing, it is argued that hybridization can still be an important evolutionary process, in the present case appearing to contribute to the range expansion of the rare E. risdonii in response to climate change.
No related grants have been discovered for Thais Ribeiro Pfeilsticker.