Rod Peakall

Australian National University | ANU · Research School of Biology (RSB)

Visual cues are of critical importance for the attraction of animal pollinators, however, little is known about the molecular mechanisms underpinning intraspecific floral colour variation. Here, we combined comparative spectral analysis, targeted metabolite profiling, multi‐tissue transcriptomics, differential gene expression, sequence analysis and...

Background and Aims Understanding the origin of pollination by sexual deception has proven challenging, as sexually deceptive flowers are often highly modified, making it hard to resolve how any intermediate forms between sexual deception and an ancestral strategy might have functioned. Here, we report the discovery in Caladenia (Orchidaceae) of se...

Flowering plants have evolved extraordinarily diverse metabolites that underpin the floral visual and olfactory signals enabling plant–pollinator interactions. In some cases, these metabolites also provide unusual rewards that specific pollinators depend on. While some metabolites are shared by most flowering plants, many have evolved in restricted...

Covering: up to September 2022Orchids are renowned not only for their diversity of floral forms, but also for their many and often highly specialised pollination strategies. Volatile semiochemicals play a crucial role in the attraction of a wide variety of insect pollinators of orchids. The compounds produced by orchid flowers are as diverse as the...

Sexually deceptive plants achieve pollination by enticing specific male insects as pollinators using a combination of olfactory, visual, and morphological mimicry. The sexually deceptive orchid genus Chiloglottis is comprised of some 30 species with predominantly dull green-red flowers except for the dark insectiform calli/callus structure from the...

A new study finds that, in the forests of tropical China, hungry hornets are lured to the fruits of Aquilaria sinensis by highly volatile compounds structurally similar to volatiles from herbivore-damaged leaves. The hornets disperse the short-lived seeds rapidly to optimal new habitats.

Biology and economics are surprisingly similar disciplines. At their core, both fields are the study of competitive interactions for scarce resources and the consequences of those interactions over time. Perhaps the first person to notice this similarity was Charles Darwin, who credited his reading of the influential economist Thomas Robert Malthus...

The Orchidaceae is rivaled only by the Asteraceae as the largest plant family, with the estimated number of species exceeding 25,000 and encompassing more than 700 genera. To gain insights into the mechanisms driving species diversity across both global and local scales, well-supported phylogenies targeting different taxonomic groups and/or geograp...

Sexually deceptive orchids exploit the innate sexual preferences of their male insect pollinators to achieve pollen transfer. Although floral volatiles are critical for pollinator attraction in sexually deceptive systems, floral morphology is also expected to exploit the sexual preferences of the pollinator. Here, we investigate the pollination of...

Orchids pollinated by sexual deception lure their specific male pollinators by sex pheromone mimicry. Despite the growing list of chemically diverse semiochemicals known to be involved, the chemical basis and flexibility of this extreme pollinator specificity are not fully understood. One promising but rarely applied tool is the synthesis and field...

Sexually deceptive plants secure pollination by luring specific male insects as pollinators using a combination of olfactory, visual, and morphological mimicry. Flower color is a key component to this attraction, but its chemical and genetic basis remains poorly understood. Chiloglottis trapeziformis is a sexually deceptive orchid which has predomi...

• The Pompilidae is a cosmopolitan and diverse group of wasps, which commonly feed on nectar. However, pollination systems specialised on pompilids have not been documented in detail outside of southern Africa. Here, we studied Caladenia drummondii (Orchidaceae), where based on floral traits and preliminary field observations we predicted pollinati...

Cross-kingdom mimicry of female insect sex pheromones by sexually deceptive orchids has evolved multiple times.¹ Fungus gnats (Diptera) are predicted to be pollinators of hundreds of sexually deceptive orchids,2, 3, 4 yet unlike orchids that sexually attract bees and wasps (Hymenoptera),5, 6, 7, 8, 9, 10, 11 the chemistry of fungus gnat-pollinated...

Fire drives animal population dynamics across many ecosystems. Yet, we still lack an understanding of how most species recover from fire and the effects of fire severity and patchiness on recovery processes. This information is crucial for fire‐mediated biodiversity conservation, particularly as fire regimes change globally. We conducted an experim...

With over 25,000 species, the drivers of diversity in the Orchidaceae remain to be fully understood. Here we outline a multi‐tiered sequence capture strategy aimed at capturing 100’s of loci to enable phylogenetic resolution from subtribe to subspecific levels in orchids of the tribe Diurideae. For the probe design, we mined subsets of 18 transcrip...

Background: Given the exceptional diversity of orchids (26,000+ species), improving strategies for the conservation of orchids will benefit a vast number of taxa. Furthermore, with rapidly increasing numbers of endangered orchids, and low success rates in orchid conservation translocation programs worldwide, it is evident that our progress in unde...

Ecological niches are crucial for species coexistence and diversification, but the niche concept has been underutilized in studying the roles of pollinators in plant evolution and reproduction. Pollination niches can be objectively characterized using pollinator traits, abundance, and distributions, as well as network topology. We review evidence t...

Natural disturbance regimes in forest ecosystems are being rapidly modified by anthropogenic pressures, including silvicultural practices and climate change. Australian forests dominated by mountain ash (Eucalyptus regnans) are critically endangered, with wildfires and clearfell logging predicted to cause ecosystem collapse within the next 50 years...

Bioactive natural products underpin the intriguing pollination strategy used by sexually deceptive orchids. These compounds, which mimic the sex pheromones of the female insect, are emitted in particular blends to lure male insect pollinators of specific species. By combining methods from field biology, analytical chemistry, electrophysiology, crys...

Caladenia is a diverse Australian genus that is exceptional among orchids in having both species pollinated by food‐seeking and sexually deceived insects. Here, we investigated the pollination of Caladenia nobilis , a species predicted to be food‐deceptive due to its large, cream‐coloured and apparently nectarless flowers. Pollinator observations w...

Trügerisches Drakolid: Der neuartige Naturstoff Drakolid (3 c) wirkt zusammen mit den beiden Hydroxymethylpyrazinen 1 und 2 als Bestäuberlockstoff in der bedrohten sexualtäuschenden Hammerorchidee Drakaea micrantha. Abstract Bioactive natural products underpin the intriguing pollination strategy used by sexually deceptive orchids. These compounds,...

Sexually deceptive orchids achieve pollination by luring male insects to flowers through chemical and sometimes visual mimicry of females. An extreme example of this deception occurs in Cryptostylis, one of only two genera where sexual deception is known to induce pollinator ejaculation. In the present study, bioassay-guided fractionations of Crypt...

Pterostylis is a diverse genus of terrestrial orchids with dull-coloured trap flowers, of which pollination has largely remained a mystery. Recently, one species has been confirmed to achieve pollination by the sexual deception of male fungus gnats. Here we assess if this pollination mechanism is used more widely in the genus. We ‘baited’ for polli...

Background and Aims The processes of gene duplication, followed by divergence and selection, probably underpin the evolution of floral volatiles crucial to plant–insect interactions. The Australian sexually deceptive Chiloglottis orchids use a class of 2,5-dialkylcyclohexan-1,3-dione volatiles or ‘chiloglottones’ to attract specific male wasp polli...

Sex‐biased mortality can lead to altered adult sex ratios (ASRs), which may in turn lead to harassment and lower fitness of the rarer sex and changes in the mating system. Female critically endangered swift parrots (Lathamus discolor) suffer high predation while nesting due to an introduced mammalian predator, the sugar glider (Petaurus breviceps)....

Pollination by sexual deception of male insects is perhaps one of the most remarkable cases of mimicry in the plant kingdom. However, understanding the influence of floral traits on pollinator behaviour in sexually deceptive orchids is challenging, due to the risk of confounding changes in floral odour when manipulating morphology. Here, we investi...

Hundreds of orchid species secure pollination by sexually luring specific male insects as pollinators by chemical and morphological mimicry. Yet, the biochemical pathways involved in the synthesis of the insect sex pheromone-mimicking volatiles in these sexually deceptive plants remain poorly understood. Here, we explore the biochemical pathways li...

Sexually deceptive orchids attract specific pollinators by mimicking insect sex pheromones. Normally this mimicry is very specific and identical compounds have been identified from orchids and matching females of the pollinators. In this study, we conduct a detailed structure-activity investigation on isomers of the semiochemicals involved in the s...

Mobile species pose major challenges for conservation because of their unpredictable, large scale movements in response to fluctuating resources. If locations with critical resources overlap with threats, large proportions of a mobile population may be exposed to threats. Critically endangered and nomadic swift parrots Lathamus discolor nest wherev...

Caladenia is exceptional among orchid genera in that it contains both species pollinated by sexual deception and species pollinated by food-foraging insects. Whereas pollination strategies have been elucidated in some species complexes, others groups have received limited attention, hampering our ability to understand the evolution of the exception...

For decades, studies have focused on how dispersal and mating systems influence genetic structure across populations or social-groups. However, we still lack a thorough understanding of how these processes and their interaction, shape spatial genetic patterns over a finer-scale (tens – hundreds of metres). Using uniparentally inherited markers may...

Flowers have evolved diverse strategies to attract animal pollinators, with visual and olfactory floral cues often crucial for pollinator attraction. While most plants provide reward (e.g., nectar, pollen) in return for the service of pollination, 1000s of plant species, particularly in the orchid family, offer no apparent reward. Instead, they exp...

The use of diversity metrics has a long history in population ecology, while population genetic work has been dominated by variance-derived metrics instead, a technical gap that has slowed cross-communication between the fields. Interestingly, Rao’s Quadratic Entropy (RQE), comparing elements for ‘degrees of divergence’, was originally developed fo...

Scaling diversity components [0,1]. (PDF)

Laboratory microsatellite protocols. (PDF)

Partitioning within-population diversity into sub-components. (PDF)

Homogeneity testing of within-stratum diversity components. (PDF)

Analysis of Rao Diversity (QDiver) for DC Matrix. (XLSX)

Analysis of Rao Diversity (QDiver) for DR Matrix. (XLSX)

Genetic tagging, the unique identification of individuals by their DNA profile, has proven to be an effective method for research on several animal species. In this study we apply non-invasive genetic tagging from feather samples to reveal the genetic structure and estimate local population size of red-and-green macaws (Ara chloropterus) without th...

Until recently, (methylthio)phenols as natural products had only been reported from bacteria. Now, four representatives of this class of sulfurous aromatic compounds have been discovered as semiochemicals in the orchid Caladenia crebra, which secures pollination by sexual deception. In this case, field bioassays confirmed that a 10:1 blend of 2-(me...

The Australian sexually deceptive orchid, Chiloglottis trapeziformis, employs a unique UV-B-dependent floral volatile, chiloglottone 1, for specific male wasp pollinator attraction. Chiloglottone 1 and related variants (2,5-dialkylcyclohexane-1,3-diones), represent a unique class of specialized metabolites presumed to be the product of cyclization...

One of the most intriguing natural observations is the pollination of orchids by sexual deception. Here, we identify floral semiochemicals from Caladenia (spider orchids) for the first time. We demonstrate that C. crebra, attracts its single pollinator species with a unique system of (methylthio)phenols, three of which are new natural products. Fur...

Recent studies using sequence data from eight sequence loci and coalescent-based species delimitation methods have revealed several species-level lineages of Tulasnella associated with the orchid genera Arthrochilus, Caleana, Chiloglottis, and Drakaea in Australia. Here we formally describe three of those species, Tulasnella prima, T. secunda, and...

Sexually deceptive orchids lure their specific male pollinators using volatile semiochemicals that mimic female sex pheromones. To date, the semiochemicals known to be involved consist of blends of chemically and biosynthetically related compounds. In contrast, we report that (S)-β-citronellol and 2-hydroxy-6-methylacetophenone, two biosyntheticall...

One of the most intriguing natural observations is the pollination of orchids by sexual deception. Here, we identify floral semiochemicals from Caladenia (spider orchids) for the first time. We demonstrate that C. crebra, attracts its single pollinator species with a unique system of (methylthio)phenols, three of which are new natural products. Fur...

The increasing availability of DNA sequence data enables exciting new opportunities for fungal ecology. However, it amplifies the challenge of how to objectively classify the diversity of fungal sequences into meaningful units, often in the absence of morphological characters. Here, we test the utility of modern multilocus Bayesian coalescent-based...

ContextDispersal is essential for species persistence and landscape genetic studies are valuable tools for identifying potential barriers to dispersal. Macaws have been studied for decades in their natural habitat, but we still have no knowledge of how natural landscape features influence their dispersal. Objectives We tested for correlations betwe...

Background: The outcome of the arms race between hosts and pathogens depends heavily on the interactions between their genetic diversity, population size and transmission ability. Theory predicts that genetically diverse hosts will select for higher virulence and more diverse pathogens than hosts with low genetic diversity. Cultivated hosts typica...

Genetic tagging is the unique identification of individuals by their DNA profile. This technique is well established in mammals, but it has not yet been widely adopted for birds. Extraction methods for minute amounts of DNA even enable the use of genetic tagging from non-invasive samples, like hair, scat, or feather. In this study, we evaluate the...

Semiochemicals are of paramount importance in sexually deceptive plants. These plants sexually lure specific male insects as pollinators by chemical and physical mimicry of the female of the pollinator. The strategy has evolved repeatedly in orchids, with a wide diversity of insect groups exploited. Chemical communication systems confirmed by field...

Sexually deceptive orchids produce floral volatiles that attract male insect pollinators. This interaction between flower and pollinator normally is highly specific. In the few cases where the chemical composition of the volatiles is known, the compounds have been found to be identical to those that comprise the sex pheromone of the female wasp. In...

An increasing diversity of highly specialized pollination systems are being discovered, many of which are likely to be vulnerable to anthropogenic landscape modification. Here, we investigate if a specialized pollination system limits the persistence of Caladenia huegelii (Orchidaceae), an endangered species pollinated by sexual deception of thynni...

1. Sexually deceptive orchids are renowned for their olfactory mimicry of female insect sex pheromones to lure male pollinators, but the role of floral morphology remains unknown. 2. Here, we reveal compelling new experimental evidence that morphology also matters in sexual deception. Our study exploited two morphologically distinct Chiloglottis or...

Sexually deceptive orchids are renowned for their olfactory mimicry of female insect sex pheromones to lure male pollinators, but the role of floral morphology remains unknown. Here, we reveal compelling new experimental evidence that morphology also matters in sexual deception. Our study exploited two morphologically distinct Chiloglottis orchids...

As species are the common currency for conserva- tion efforts, their accurate description is essential for efficient preservation of biological diversity. The use of DNA Barcodes, short DNA sequences that evolve fast enough to differentiate species, has been pro- posed both for the discovery of new species and the identification of previously descr...

The majority of flowering plants rely on animals as pollen vectors. Thus, plant mating systems and pollen dispersal are strongly influenced by pollinator behaviour. In Australian sexually deceptive orchids pollinated by male thynnine wasps, outcrossing and extensive pollen flow is predicted due to floral deception, which minimises multiple flower v...

Reconstructing evolutionary history for emerging species complexes is notoriously difficult, with newly isolated taxa often morphologically cryptic and the signature of reproductive isolation often restricted to a few genes. Evidence from multiple loci and genomes is highly desirable, but multiple inputs require 'common currency' translation. Here...

Natal sex-biased dispersal has long been thought to reduce the risk of inbreeding by spatially separating opposite-sexed kin. Yet, comprehensive and quantitative evaluations of this hypothesis are lacking. In this study, we quantified the effectiveness of sex-biased dispersal as an inbreeding avoidance strategy by combining spatially-explicit simul...

Primer pairs were designed for 41 di-nucleotide microsatellite loci identified from across the full genome of the Scarlet Macaw (Ara macao). We present the best 30 polymorphic loci with 5–22 alleles, 3–14 effective alleles and expected heterozygosities of 0.669–0.930. These markers will facilitate population genetic and conservation genetic studies...

Australian sexually deceptive Chiloglottis orchids attract their specific male wasp pollinators by means of 2,5-dialkylcyclohexane-1,3-diones or 'chiloglottones', representing a newly discovered class of volatiles with unique structures. This study investigated the hypothesis that UV-B light at low intensities is directly required for chiloglottone...