ORCID Profile
0000-0002-4014-8478
Current Organisations
Edith Cowan University
,
Macquarie University
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Genomics | Population, Ecological and Evolutionary Genetics | Biologically Active Molecules | Genetics
Flora, Fauna and Biodiversity of environments not elsewhere classified | Horticultural Crops not elsewhere classified |
Publisher: Oxford University Press (OUP)
Date: 30-04-2018
DOI: 10.1534/GENETICS.118.300748
Abstract: Self-incompatibility (SI) is a genetically based recognition system that functions to prevent self-fertilization and mating among related plants. An enduring puzzle in SI is how the high ersity observed in nature arises and is maintained. Based on the underlying recognition mechanism, SI can be classified into two main groups: self-recognition (SR) and nonself-recognition (NSR). Most work has focused on ersification within SR systems despite expected differences between the two groups in the evolutionary pathways and outcomes of ersification. Here, we use a deterministic population genetic model and stochastic simulations to investigate how novel S-haplotypes evolve in a gametophytic NSR [SRNase/S Locus F-box (SLF)] SI system. For this model, the pathways for ersification involve either the maintenance or breakdown of SI and can vary in the order of mutations of the female (SRNase) and male (SLF) components. We show analytically that ersification can occur with high inbreeding depression and self-pollination, but this varies with evolutionary pathway and level of completeness (which determines the number of potential mating partners in the population), and, in general, is more likely for lower haplotype number. The conditions for ersification are broader in stochastic simulations of finite population size. However, the number of haplotypes observed under high inbreeding and moderate-to-high self-pollination is less than that commonly observed in nature. Diversification was observed through pathways that maintain SI as well as through self-compatible intermediates. Yet the lifespan of ersified haplotypes was sensitive to their level of completeness. By examining ersification in a NSR SI system, this model extends our understanding of the evolution and maintenance of haplotype ersity observed in a recognition system common in flowering plants.
Publisher: Springer Science and Business Media LLC
Date: 27-07-2021
DOI: 10.1007/S10531-021-02256-X
Abstract: Understanding the timescales that shape spatial genetic structure is pivotal to ascertain the impact of habitat fragmentation on the genetic ersity and reproductive viability of long-lived plant populations. Combining genetic and ecological information with current and past fragmentation conditions allows the identification of the main drivers important in shaping population structure and declines in reproduction, which is crucial for informing conservation strategies. Using historic aerial photographs, we defined the past fragmentation conditions for the shrub Conospermum undulatum , a species now completely embedded in an urban area. We explored the impact of current and past conditions on its genetic layout and assessed the effects of genetic and environmental factors on its reproduction. The historically high structural connectivity was evident in the genetics of the species. Despite the current intense fragmentation, we found similar levels of genetic ersity across populations and a weak spatial genetic structure. Historical connectivity was negatively associated with genetic differentiation among populations and positively related to within-population genetic ersity. Variation partitioning of reproductive performance explained ~ 66% of the variance, showing significant influences for genetic (9%), environmental (15%), and combined (42%) fractions. Our study highlights the importance of considering the historical habitat dynamics when investigating fragmentation consequences in long-lived plants. A detailed characterization of fragmentation from 1953 has shown how low levels of genetic fixation are due to extensive gene flow through the non-fragmented landscape. Moreover, knowledge of the relationships between genetic and environmental variation and reproduction can help to implement effective conservation strategies, particularly in highly dynamic landscapes.
Publisher: Oxford University Press (OUP)
Date: 27-04-2016
DOI: 10.1093/AOB/MCW043
Publisher: Wiley
Date: 07-03-2011
Publisher: Springer Science and Business Media LLC
Date: 13-09-2021
Publisher: Wiley
Date: 15-10-2008
Publisher: Wiley
Date: 09-10-2019
DOI: 10.1111/NPH.16180
Publisher: Wiley
Date: 04-2019
DOI: 10.1111/MEC.15048
Publisher: MDPI AG
Date: 16-11-2021
Abstract: Vegetables and herbs play a central role in the human diet due to their low fat and calory content and essential antioxidant, phytochemicals, and fiber. It is well known that the manipulation of light wavelengths illuminating the crops can enhance their growth rate and nutrient contents. To date, it has not been easy to generalize the effects of LED illumination because of the differences in the plant species investigated, the measured traits, the way wavelengths have been manipulated, and the plants’ growing environments. In order to address this gap, we undertook a quantitative review of LED manipulation in relation to plant traits, focusing on vegetables and herbs. Here, we use standardized measurements of biomass, antioxidant, and other quantitative characteristics together with the whole range of the photosynthetic photon flux density (PPFD). Overall, our review revealed support for the claims that the red and blue LED illumination is more reliable and efficient than full spectrum illumination and increases the plant’s biomass and nutritional value by enhancing the photosynthetic activity, antioxidant properties, phenolic, and flavonoids contents. Although LED illumination provides an efficient way to improve yield and modify plant properties, this study also highlights the broad range of responses among species, varieties traits, and the age of plant material.
Publisher: Proceedings of the National Academy of Sciences
Date: 08-10-2018
Abstract: Populations often show “islands of ergence” in the genome. Analysis of ergence between subspecies of Antirrhinum that differ in flower color patterns shows that sharp peaks in relative ergence occur at two causal loci. The island is shaped by a combination of gene flow and multiple selective sweeps, showing how ergence and barriers between populations can arise and be maintained.
Publisher: University of Chicago Press
Date: 02-2012
DOI: 10.1086/663164
Publisher: The Royal Society
Date: 13-07-2020
Publisher: Wiley
Date: 28-05-2018
Abstract: Pedigree and sibship reconstruction are important methods in quantifying relationships and fitness of in iduals in natural populations. Current methods employ a Markov chain-based algorithm to explore plausible possible pedigrees iteratively. This provides accurate results, but is time-consuming. Here, we develop a method to infer sibship and paternity relationships from half-sibling arrays of known maternity using hierarchical clustering. Given 50 or more unlinked SNP markers and empirically derived error rates, the method performs as well as the widely used package Colony, but is faster by two orders of magnitude. Using simulations, we show that the method performs well across contrasting mating scenarios, even when s les are large. We then apply the method to open-pollinated arrays of the snapdragon Antirrhinum majus and find evidence for a high degree of multiple mating. Although we focus on diploid SNP data, the method does not depend on marker type and as such has broad applications in nonmodel systems.
Publisher: The Royal Society
Date: 07-01-2013
Abstract: Understanding the relative importance of heterosis and outbreeding depression over multiple generations is a key question in evolutionary biology and is essential for identifying appropriate genetic sources for population and ecosystem restoration. Here we use 2455 experimental crosses between 12 population pairs of the rare perennial plant Rutidosis leptorrhynchoides (Asteraceae) to investigate the multi-generational (F 1 , F 2 , F 3 ) fitness outcomes of inter-population hybridization. We detected no evidence of outbreeding depression, with inter-population hybrids and backcrosses showing either similar fitness or significant heterosis for fitness components across the three generations. Variation in heterosis among population pairs was best explained by characteristics of the foreign source or home population, and was greatest when the source population was large, with high genetic ersity and low inbreeding, and the home population was small and inbred. Our results indicate that the primary consideration for maximizing progeny fitness following population augmentation or restoration is the use of seed from large, genetically erse populations.
Publisher: Wiley
Date: 08-2021
DOI: 10.1111/NPH.17581
Abstract: Parallel evolution of similar morphologies in closely related lineages provides insight into the repeatability and predictability of evolution. In the genus Antirrhinum (snapdragons), as in other plants, a suite of morphological characters are associated with adaptation to alpine environments. We tested for parallel trait evolution in Antirrhinum by investigating phylogenetic relationships using restriction‐site associated DNA (RAD) sequencing. We then associated phenotypic information to our phylogeny to reconstruct the patterns of morphological evolution and related this to evidence for hybridisation between emergent lineages. Phylogenetic analyses showed that the alpine character syndrome is present in multiple groups, suggesting that Antirrhinum has repeatedly colonised alpine habitats. Dispersal to novel environments happened in the presence of intraspecific and interspecific gene flow. We found support for a model of parallel evolution in Antirrhinum . Hybridisation in natural populations, and a complex genetic architecture underlying the alpine morphology syndrome, support an important role of natural selection in maintaining species ergence in the face of gene flow.
Publisher: University of Chicago Press
Date: 11-2005
DOI: 10.1086/467473
Publisher: Elsevier BV
Date: 11-2022
DOI: 10.1016/J.SCITOTENV.2022.157556
Abstract: Global food production, food supply chains and food security are increasingly stressed by human population growth and loss of arable land, becoming more vulnerable to anthropogenic and environmental perturbations. Numerous mutualistic and antagonistic species are interconnected with the cultivation of crops and livestock and these can be challenging to identify on the large scales of food production systems. Accurate identifications to capture this ersity and rapid scalable monitoring are necessary to identify emerging threats (i.e. pests and pathogens), inform on ecosystem health (i.e. soil and pollinator ersity), and provide evidence for new management practices (i.e. fertiliser and pesticide applications). Increasingly, environmental DNA (eDNA) is providing rapid and accurate classifications for specific organisms and entire species assemblages in substrates ranging from soil to air. Here, we aim to discuss how eDNA is being used for monitoring of agricultural ecosystems, what current limitations exist, and how these could be managed to expand applications into the future. In a systematic review we identify that eDNA-based monitoring in food production systems accounts for only 4 % of all eDNA studies. We found that the majority of these eDNA studies target soil and plant substrates (60 %), predominantly to identify microbes and insects (60 %) and are biased towards Europe (42 %). While eDNA-based monitoring studies are uncommon in many of the world's food production systems, the trend is most pronounced in emerging economies often where food security is most at risk. We suggest that the biggest limitations to eDNA for agriculture are false negatives resulting from DNA degradation and assay biases, as well as incomplete databases and the interpretation of abundance data. These require in silico, in vitro, and in vivo approaches to carefully design, test and apply eDNA monitoring for reliable and accurate taxonomic identifications. We explore future opportunities for eDNA research which could further develop this useful tool for food production system monitoring in both emerging and developed economies, hopefully improving monitoring, and ultimately food security.
Publisher: Wiley
Date: 19-07-2012
Publisher: Authorea, Inc.
Date: 24-06-2023
DOI: 10.22541/AU.168757928.84749825/V1
Abstract: Globally, the ersity of arthropods and the plants upon which they rely are under increasing pressure due to a combination of biotic and abiotic anthropogenic stressors. Unfortunately, conventional survey methods used to monitor ecosystems are often challenging to conduct at large scales. Pan traps are a commonly used pollinator survey method and environmental DNA (eDNA) metabarcoding of pan-trap water may offer a high-throughput alternative to aid in the detection of both arthropods and the plant resources they rely on. Here, we examined if eDNA metabarcoding can be used to identify arthropod and plant species from pan-trap water, and invesitigated the effect of different DNA extraction methods. We then compared plant species identified by metabarcoding with observation-based floral surveys and also assessed the contribution of airborne plant DNA (plant DNA not carried by arthropods) using marble traps to reduce putative false positives in the pan trap dataset. Arthropod eDNA was only detected in 17% of pan trap s les and there was minimal overlap between the eDNA results and morphological identifications. In contrast, for plants, we detected 64 taxa, of which 53 were unique to the eDNA dataset, and no differences were identified between the two extraction kits. We were able to significantly reduce the contribution of airborne plant DNA to the final dataset using marble traps. This study demonstrates that eDNA metabarcoding of pan-trap water can detect plant resources used by arthropods and highlights the potential for eDNA metabarcoding to be applied to investigations of plant-animal interactions.
Publisher: Wiley
Date: 26-05-2023
Abstract: In the face of global bio ersity declines, surveys of beneficial and antagonistic arthropod ersity as well as the ecological services that they provide are increasingly important in both natural and agro‐ecosystems. Conventional survey methods used to monitor these communities often require extensive taxonomic expertise and are time‐intensive, potentially limiting their application in industries such as agriculture, where arthropods often play a critical role in productivity (e.g. pollinators, pests and predators). Environmental DNA (eDNA) metabarcoding of a novel substrate, crop flowers, may offer an accurate and high throughput alternative to aid in the detection of these managed and unmanaged taxa. Here, we compared the arthropod communities detected with eDNA metabarcoding of flowers, from an agricultural species ( Persea americana —‘Hass’ avocado), with two conventional survey techniques: digital video recording (DVR) devices and pan traps. In total, 80 eDNA flower s les, 96 h of DVRs and 48 pan trap s les were collected. Across the three methods, 49 arthropod families were identified, of which 12 were unique to the eDNA dataset. Environmental DNA metabarcoding from flowers revealed potential arthropod pollinators, as well as plant pests and parasites. Alpha ersity levels did not differ across the three survey methods although taxonomic composition varied significantly, with only 12% of arthropod families found to be common across all three methods. eDNA metabarcoding of flowers has the potential to revolutionize the way arthropod communities are monitored in natural and agro‐ecosystems, potentially detecting the response of pollinators and pests to climate change, diseases, habitat loss and other disturbances.
Publisher: Cold Spring Harbor Laboratory
Date: 21-08-2020
DOI: 10.1101/2020.08.20.259036
Abstract: Many studies have quantified the distribution of heterozygosity and relatedness in natural populations, but surprisingly few have examined the demographic processes driving these patterns. In this study we take a novel approach by studying how population structure affects both pairwise identity and the distribution of heterozygosity in a natural population of a self-incompatible plant Antirrhinum majus . We look at a measure of the variance in heterozygosity within a population, identity disequilibrium ( g 2 ), together with F ST using a panel of 91 SNPs in 22,353 in iduals collected over 11 years. We find that pairwise relatedness (F ST ) declines rapidly over short spatial scales, and the excess variance in heterozygosity between in iduals ( g 2 ) reflects significant variation in inbreeding. Additionally, we detect an excess of in iduals with around half the average heterozygosity, indicating that some are due to selfing or matings between close relatives. We use two types of simulation to ask whether variation in heterozygosity is consistent with fine-scale spatial population structure. First, by simulating offspring using parents drawn from a range of spatial scales, we show that the known pollen dispersal kernel explains g 2 . Second, we simulate a 1000-generation pedigree using the known dispersal and spatial distribution and find that the resulting g 2 is consistent with that observed from the field data. In contrast, a simulated population with uniform density underestimates g 2 , indicating that heterogeneous density promotes identity disequilibrium. Our study shows that heterogeneous density and leptokurtic dispersal can together explain the distribution of heterozygosity. Furthermore, our study highlights the limitations of making theoretical predictions from simulations that only assume simple density and dispersal distributions.
Publisher: Wiley
Date: 20-12-2013
DOI: 10.1111/EVO.12001
Abstract: Dioecious plant species commonly exhibit deviations from the equilibrium expectation of 1:1 sex ratio, but the mechanisms governing this variation are poorly understood. Here, we use comparative analyses of 243 species, representing 123 genera and 61 families to investigate ecological and genetic correlates of variation in the operational (flowering) sex ratio. After controlling for phylogenetic nonindependence, we examined the influence of growth form, clonality, fleshy fruits, pollen and seed dispersal vector, and the possession of sex chromosomes on sex-ratio variation. Male-biased flowering sex ratios were twice as common as female-biased ratios. Male bias was associated with long-lived growth forms (e.g., trees) and biotic seed dispersal and fleshy fruits, whereas female bias was associated with clonality, especially for herbaceous species, and abiotic pollen dispersal. Female bias occurred in species with sex chromosomes and there was some evidence for a greater degree of bias in those with heteromorphic sex chromosomes. Although the role of interactions among these correlates require further study, our results indicate that sex-based differences in costs of reproduction, pollen and seed dispersal mechanisms and sex chromosomes can each play important roles in affecting flowering sex ratios in dioecious plants.
Publisher: Oxford University Press (OUP)
Date: 26-02-2013
DOI: 10.1093/AOB/MCT040
Publisher: Authorea, Inc.
Date: 20-12-2022
DOI: 10.22541/AU.167154130.03331517/V1
Abstract: In the face of global bio ersity declines, surveys of beneficial and antagonistic arthropod ersity as well as the ecological services that they provide are increasingly important in both natural and agro-ecosystems. Conventional survey methods used to monitor these communities often require extensive taxonomic expertise and are time-intensive, potentially limiting their application in industries such as agriculture, where arthropods often play a critical role in productivity (e.g. pollinators, pests and predators). Environmental DNA (eDNA) metabarcoding of a novel substrate, crop flowers, may offer an accurate and high throughput alternative to aid in the detection managed and unmanaged arthropod taxa (e.g. flower-visiting insects and potential pollinators). Here, we compared the arthropod communities detected with eDNA metabarcoding of flowers, from an agricultural species (Persea americana - ‘Hass’ avocado), with two conventional survey techniques Digital Video Recording (DVR) devices and pan traps. In total, 80 eDNA flower s les, 96 hours of DVRs and 48 pan trap s les were collected. Across the three methods, 49 arthropod families were identified, of which 12 were unique to the eDNA dataset. Alpha ersity levels did not differ across the three survey methods although taxonomic composition varied significantly, with only 12% of arthropod families found to be common across all three methods. This study demonstrates that eDNA metabarcoding of flowers to detect visiting arthropods, although in a developmental stage, can complement traditional survey methods and increase the ersity of taxa detected with implications for both natural and agro-ecosystems.
Publisher: Springer Science and Business Media LLC
Date: 10-11-2011
DOI: 10.1038/HDY.2010.127
Publisher: American Association for the Advancement of Science (AAAS)
Date: 17-11-2017
Abstract: In some snapdragons, a yellow spot in a field of magenta shows the bee the best place to go. Flowers of a related subspecies are mainly yellow with magenta veins marking the target. Bradley et al. analyzed a locus that regulates the pattern of color. The locus contains an inverted gene duplication that encodes small RNAs that repress pigment biosynthesis. Analysis of flowers derived from a region of the Pyrenees where the subspecies coexist indicates that natural selection is operating upon the locus. Science , this issue p. 925
Publisher: Cold Spring Harbor Laboratory
Date: 27-08-2021
DOI: 10.1101/2021.08.26.457771
Abstract: Speciation, the continuous process by which new species form, is often investigated by looking at the variation of nucleotide ersity and differentiation across the genome (hereafter genomic landscapes). A key challenge lies in how to determine the main evolutionary forces at play shaping these patterns. One promising strategy, albeit little used to date, is to comparatively investigate these genomic landscapes as a progression through time by using a series of species pairs along a ergence gradient. Here, we resequenced 201 whole-genomes from eight closely related Populus species, with pairs of species at different stages along the ergence gradient to learn more about speciation processes. Using population structure and ancestry analyses, we document extensive introgression between some species pairs, especially those with parapatric distributions. We further investigate genomic landscapes, focusing on within-species (nucleotide ersity and recombination rate) and among-species (relative and absolute ergence) summary statistics of ersity and ergence. We observe highly conserved patterns of genomic ergence across species pairs. Independent of the stage across the ergence gradient, we find support for signatures of linked selection (i.e., the interaction between natural selection and genetic linkage) in shaping these genomic landscapes, along with gene flow and standing genetic variation. We highlight the importance of investigating genomic patterns on multiple species across a ergence gradient and discuss prospects to better understand the evolutionary forces shaping the genomic landscapes of ersity and differentiation.
Publisher: The Royal Society
Date: 13-07-2020
Abstract: Many recent studies have addressed the mechanisms operating during the early stages of speciation, but surprisingly few studies have tested theoretical predictions on the evolution of strong reproductive isolation (RI). To help address this gap, we first undertook a quantitative review of the hybrid zone literature for flowering plants in relation to reproductive barriers. Then, using Populus as an exemplary model group, we analysed genome-wide variation for phylogenetic tree topologies in both early- and late-stage speciation taxa to determine how these patterns may be related to the genomic architecture of RI. Our plant literature survey revealed variation in barrier complexity and an association between barrier number and introgressive gene flow. Focusing on Populus, our genome-wide analysis of tree topologies in speciating poplar taxa points to unusually complex genomic architectures of RI, consistent with earlier genome-wide association studies. These architectures appear to facilitate the ‘escape’ of introgressed genome segments from polygenic barriers even with strong RI, thus affecting their relationships with recombination rates. Placed within the context of the broader literature, our data illustrate how phylogenomic approaches hold great promise for addressing the evolution and temporary breakdown of RI during late stages of speciation. This article is part of the theme issue ‘Towards the completion of speciation: the evolution of reproductive isolation beyond the first barriers'.
Publisher: Wiley
Date: 12-08-2019
DOI: 10.1111/NPH.16050
Publisher: Springer Science and Business Media LLC
Date: 15-08-2009
Publisher: The Royal Society
Date: 27-08-2010
Abstract: In many angiosperm species, populations are reproductively sub ided into distinct sexual morphs including females, males and hermaphrodites. Sexual polymorphism is maintained by frequency-dependent selection, leading to predictable sex ratios at equilibrium. Charles Darwin devoted much of his book ‘ The Different Forms of Flowers on Plants of the Same Species ’ (1877) to investigating plant sexual polymorphisms and laid the foundation for many problems addressed today by integrating theory with empirical studies of the demography and genetics of populations. Here, we summarize our recent work on the ecological and genetic mechanisms influencing variation in sex ratios and their implications for evolutionary transitions among sexual systems. We present the results of a survey of sex ratios from 126 species from 47 angiosperm families and then address two general problems using ex les from erse angiosperm taxa: (i) the mechanisms governing biased sex ratios in dioecious species (ii) the origins and maintenance of populations composed of females, males and hermaphrodites. Several themes are emphasized, including the importance of non-equilibrium conditions, the role of life history and demography in affecting sex ratios, the value of theory for modelling the dynamics of sex ratio variation, and the utility of genetic markers for investigating evolutionary processes in sexually polymorphic plant populations.
Publisher: Informa UK Limited
Date: 04-12-2019
Publisher: Oxford University Press (OUP)
Date: 27-05-2022
Abstract: Many studies have quantified the distribution of heterozygosity and relatedness in natural populations, but few have examined the demographic processes driving these patterns. In this study, we take a novel approach by studying how population structure affects both pairwise identity and the distribution of heterozygosity in a natural population of the self-incompatible plant Antirrhinum majus. Excess variance in heterozygosity between in iduals is due to identity disequilibrium, which reflects the variance in inbreeding between in iduals it is measured by the statistic g2. We calculated g2 together with FST and pairwise relatedness (Fij) using 91 SNPs in 22,353 in iduals collected over 11 years. We find that pairwise Fij declines rapidly over short spatial scales, and the excess variance in heterozygosity between in iduals reflects significant variation in inbreeding. Additionally, we detect an excess of in iduals with around half the average heterozygosity, indicating either selfing or matings between close relatives. We use 2 types of simulation to ask whether variation in heterozygosity is consistent with fine-scale spatial population structure. First, by simulating offspring using parents drawn from a range of spatial scales, we show that the known pollen dispersal kernel explains g2. Second, we simulate a 1,000-generation pedigree using the known dispersal and spatial distribution and find that the resulting g2 is consistent with that observed from the field data. In contrast, a simulated population with uniform density underestimates g2, indicating that heterogeneous density promotes identity disequilibrium. Our study shows that heterogeneous density and leptokurtic dispersal can together explain the distribution of heterozygosity.
Publisher: Oxford University Press (OUP)
Date: 03-2018
DOI: 10.1534/GENETICS.117.300638
Abstract: Ringbauer et al. introduce a novel method to estimate barriers to gene flow in a two-dimensional population. Their inference scheme utilizes geographically... In continuous populations with local migration, nearby pairs of in iduals have on average more similar genotypes than geographically well-separated pairs. A barrier to gene flow distorts this classical pattern of isolation by distance. Genetic similarity is decreased for s le pairs on different sides of the barrier and increased for pairs on the same side near the barrier. Here, we introduce an inference scheme that uses this signal to detect and estimate the strength of a linear barrier to gene flow in two dimensions. We use a diffusion approximation to model the effects of a barrier on the geographic spread of ancestry backward in time. This approach allows us to calculate the chance of recent coalescence and probability of identity by descent. We introduce an inference scheme that fits these theoretical results to the geographic covariance structure of bialleleic genetic markers. It can estimate the strength of the barrier as well as several demographic parameters. We investigate the power of our inference scheme to detect barriers by applying it to a wide range of simulated data. We also showcase an ex le application to an Antirrhinum majus (snapdragon) flower-color hybrid zone, where we do not detect any signal of a strong genome-wide barrier to gene flow.
Publisher: Elsevier BV
Date: 04-2022
Publisher: Wiley
Date: 04-06-2023
DOI: 10.1111/MEC.17034
Abstract: Speciation, the continuous process by which new species form, is often investigated by looking at the variation of nucleotide ersity and differentiation across the genome (hereafter genomic landscapes). A key challenge lies in how to determine the main evolutionary forces at play shaping these patterns. One promising strategy, albeit little used to date, is to comparatively investigate these genomic landscapes as progression through time by using a series of species pairs along a ergence gradient. Here, we resequenced 201 whole‐genomes from eight closely related Populus species, with pairs of species at different stages along the ergence gradient to learn more about speciation processes. Using population structure and ancestry analyses, we document extensive introgression between some species pairs, especially those with parapatric distributions. We further investigate genomic landscapes, focusing on within‐species (i.e. nucleotide ersity and recombination rate) and among‐species (i.e. relative and absolute ergence) summary statistics of ersity and ergence. We observe relatively conserved patterns of genomic ergence across species pairs. Independent of the stage across the ergence gradient, we find support for signatures of linked selection (i.e. the interaction between natural selection and genetic linkage) in shaping these genomic landscapes, along with gene flow and standing genetic variation. We highlight the importance of investigating genomic patterns on multiple species across a ergence gradient and discuss prospects to better understand the evolutionary forces shaping the genomic landscapes of ersity and differentiation.
Publisher: Wiley
Date: 17-07-2012
Publisher: Wiley
Date: 27-05-2015
DOI: 10.1111/PLB.12336
Abstract: Sexual dimorphism in resource allocation is expected to change during the life cycle of dioecious plants because of temporal differences between the sexes in reproductive investment. Given the potential for sex-specific differences in reproductive costs, resource availability may contribute to variation in reproductive allocation in females and males. Here, we used Rumex hastatulus, a dioecious, wind-pollinated annual plant, to investigate whether sexual dimorphism varies with life-history stage and nutrient availability, and determine whether allocation patterns differ depending on reproductive commitment. To examine if the costs of reproduction varied between the sexes, reproduction was either allowed or prevented through bud removal, and biomass allocation was measured at maturity. In a second experiment to assess variation in sexual dimorphism across the life cycle, and whether this varied with resource availability, plants were grown in high and low nutrients and allocation to roots, aboveground vegetative growth and reproduction were measured at three developmental stages. Males prevented from reproducing compensated with increased above- and belowground allocation to a much larger degree than females, suggesting that male reproductive costs reduce vegetative growth. The proportional allocation to roots, reproductive structures and aboveground vegetative growth varied between the sexes and among life-cycle stages, but not with nutrient treatment. Females allocated proportionally more resources to roots than males at peak flowering, but this pattern was reversed at reproductive maturity under low-nutrient conditions. Our study illustrates the importance of temporal dynamics in sex-specific resource allocation and provides support for high male reproductive costs in wind-pollinated plants.
Publisher: Springer Science and Business Media LLC
Date: 04-10-2017
DOI: 10.1038/HDY.2017.51
Start Date: 2019
End Date: 2022
Funder: FWF Austrian Science Fund
View Funded ActivityStart Date: 10-2022
End Date: 10-2025
Amount: $499,654.00
Funder: Australian Research Council
View Funded Activity