Allan G. Ellis

• PhD
• Professor (Associate) at Stellenbosch University

Floral tubes are often thought to be a consequence of adaptive specialization towards pollinator morphology. We explore floral tube length evolution within Tritoniopsis revoluta (Iridaceae), a species with considerable geographical tube length variation. We ask whether tube lengths of T. revoluta populations are associated with pollinator proboscis...

Phenotypic integration, the coordinated covariance of suites of morphological traits, is critical for proper functioning of organisms. Angiosperm flowers are complex structures comprising suites of traits that function together to achieve effective pollen transfer. Floral integration could reflect shared genetic and developmental control of these t...

Dispersal and breeding system traits are thought to affect colonization success. As species have attained their present distribution ranges through colonization, these traits may vary geographically. Although several theories predict associations between dispersal ability, selfing ability and the relative position of a population within its geograp...

The costs that species suffer when deceived are expected to drive learned resistance, although this relationship has seldom been studied experimentally. Flowers that elicit mating behaviour from male insects by mimicking conspecific females provide an ideal system for such investigation. Here, we explore interactions between a sexually deceptive da...

Background and AimsFloral polymorphism is frequently attributed to pollinator-mediated selection. Multiple studies, however, have revealed the importance of non-pollinating visitors in floral evolution. Using the polymorphic annual daisy Ursinia calenduliflora, this study investigated the importance of different insect visitors, and their effects o...

Phylogenetic relationships in the South African daisy genus Dimorphotheca have long been uncertain, with the taxonomy of the genus relying on a few morphological traits, most prominently capitulum sexual system (e.g., cypsela type) and ray colour, which may not be evolutionarily conserved. Here we present the first well-sampled molecular phylogeny...

Plants employ a diversity of reproductive safeguarding strategies to circumvent the challenge of pollen limitation. Focusing on southern African Lachenalia (Asparagaceae: Scilloideae), we test the hypothesis that the evolution of reproductive safeguarding traits (self‐compatibility, autonomous selfing, bird pollination and clonal propagation) is fa...

Measuring the strength of different reproductive barriers across species pairs is key to reveal the mechanisms that have led to evolutionary radiations. Here we study a genus of miniature plants, Argyroderma, which comprises 11 species restricted to a single plain of the Southern African desert. We measure different reproductive barriers to underst...

Gene co-option, the redeployment of an existing gene in an unrelated developmental context, is an important mechanism underlying the evolution of morphological novelty. In most cases described to date, novel traits emerged by co-option of a single gene or genetic network. Here, we show that the integration of multiple co-opted genetic elements faci...

Nemestrinidae (tangle-veined flies) are important pollinators of numerous southern African plant species. Despite their known ecological importance, the family has received little taxonomic attention in recent years and the systematics of the group is poorly understood. In this study we aimed to assess the phylogenetic relationships and species div...

The morphologically diverse daisy species Gorteria diffusa employs varying levels of sexually deceptive pollination. The species comprises at least fifteen spatially and phenotypically discrete floral morphotypes that are associated with a range of pollination strategies, from generalism to highly specialised sexual deception involving visual mimic...

Generic circumscription in the small daisy tribe Calenduleae has been unstable, with various authors recognising between three and twelve genera. Evaluating alternative generic circumscriptions is difficult since existing phylogenetic hypotheses are poorly sampled. We assemble a preliminary phylogenetic hypothesis for the tribe based on nuclear rib...

Invasive Australian acacias cause substantial biodiversity impacts in South Africa's Core Cape Subregion (CCR) via positive plant-soil feedbacks, driven by high growth rates and leaf litter input by these legumes and their associations with nitrogen-fixing rhizobia. However, it is unclear whether acacia-induced soil abiotic conditions, or the assoc...

Many flowers change colour as they age or after pollination, which can have direct effects on pollinator behaviour affecting both pollination (on the plant side) and foraging efficiency (on the insect side). The retention of colour-changed flowers might increase plant attractiveness to pollinators over long distances, while directing pollinators at...

While co-flowering plants often compete for pollination through pollinator visits and pollen transfer, recent studies reveal potential for the facilitation of pollination. Pollination may be promoted when similarities in the floral traits of co-flowering species enhance pollinator visitation and seed set. Floral similarity, however, could also lead...

Mutualisms can be disrupted when non-native plants are introduced into novel environments, potentially impacting their establishment success. Introduced species can reassemble mutualisms by forming novel associations with resident biota or by maintaining familiar associations when they are co-introduced with their mutualists. Invasive Australian Ac...

Lachenalia (Asparagaceae; Scilloideae; Hyacintheae) is a large and morphologically diverse genus of more than 140 bulbous species endemic to southern Africa. Previous attempts to infer a well‐resolved and robustly supported phylogeny of Lachenalia using Sanger sequencing of candidate loci and/or morphological characters have been largely unsuccessf...

Despite evidence of pollinator declines from many regions across the globe, the threat this poses to plant populations is not clear because plants can often produce seeds without animal pollinators. Here, we quantify pollinator contribution to seed production by comparing fertility in the presence versus the absence of pollinators for a global data...

Invasive plants often impact soil conditions, notably through changes in soil chemistry and microbial community composition, potentially leading to altered soil functionality. We determine the impacts of invasive nitrogen-fixing Australian Acacia trees on soil chemistry and function (carbon, nitrogen, and phosphorus cycling) in South Africa’s Core...

The striking variation in flower color across and within Angiosperm species is often attributed to divergent selection resulting from geographic mosaics of pollinators with different color preferences. Despite the importance of pollinator mosaics in driving floral divergence, the distributions of pollinators and their color preferences are seldom q...

While the tempo of diversification in biodiversity hotspots has received much attention, the spatial scale of diversification has often been overlooked. Addressing this deficiency requires understanding the drivers of population divergence and the spatial scales at which they operate in species‐rich clades and ecosystems. South Africa's Succulent K...

Bombyliidae is a very species‐rich and widespread family of parasitoid flies with more than 250 genera classified into 17 extant subfamilies. However, little is known about their evolutionary history or how their present‐day diversity was shaped. Transcriptomes of 15 species and anchored hybrid enrichment (AHE) sequence captures of 86 species, repr...

Long-proboscid nemestrinid flies are keystone pollinators of dozens of Southern African plants and, consequently, their taxonomic status might have important consequences for insect and plant conservation. We focus on Prosoeca peringueyi, considered to be a single, morphologically variable species, upon which a guild of ~28 plants in the winter rai...

Land use change, by disrupting the co-evolved interactions between plants and their pollinators, could be causing plant reproduction to be limited by pollen supply. Using a phylogenetically controlled meta-analysis on over 2200 experimental studies and more than 1200 wild plants, we ask if land use intensification is causing plant reproduction to b...

While biodiversity hotspots are typically identified on the basis of species number per unit area, their exceptional richness is often attributed, either implicitly or explicitly, to high diversification rates. High species concentrations, however, need not reflect rapid diversification, with the diversity of some hotspots accumulating at modest ra...

What makes some species successful invaders while others fail, and why some invaders have major impacts in invaded ecosystems are pivotal questions that are attracting major research effort. The increasing availability of high resolution, georeferenced stable isotope landscapes (‘isoscapes’), coupled with the commercialization of stable isotope‐enr...

Floral apparency is shaped by both mutualistic and antagonistic interactions that can act in opposing ways. Pollinators are expected to select for more visually apparent flowers, but this likely trades off against the potentially severe fitness costs of damage to apparent flowers by floral herbivores. One way in which flowers that close during part...

Following their establishment in new communities, invasive species may cause evolutionary changes in resident native species. This is clearly true for phytophagous insects, which may adapt rapidly when utilising abundant and widespread introduced hosts. The balloon vines Cardiospermumhalicacabum and C.grandiflorum were introduced to South Africa ap...

Soil bacteria play an important role in ecosystem functioning and regulate the health and diversity of aboveground plant communities. South Africa's fynbos vegetation, part of a global biodiversity hotspot with a well-characterised flora, is highly threatened and fragmented. Surprisingly, very little is known about the belowground communities that...

The role of pollination in the success of invasive plants needs to be understood because invasives have substantial effects on species interactions and ecosystem functions. Previous research has shown both that reproduction of invasive plants is often pollen limited and that invasive plants can have high seed production, motivating the questions: H...

Aim Mutualisms are often disrupted for plants introduced to new ranges, yet many of these plants have managed to obtain effective mutualistic associations in their new ranges. There are two potential pathways for non‐native plants to reassemble mutualisms: cointroduction (i.e. familiar associations with cointroduced mutualists) or ecological fittin...

J. H. Burns was omitted in error from the author list of the original version of this Data Descriptor. This omission has now been corrected in both the HTML and PDF versions.

Plant reproduction relies on transfer of pollen from anthers to stigmas, and the majority of flowering plants depend on biotic or abiotic agents for this transfer. A key metric for characterizing if pollen receipt is insufficient for reproduction is pollen limitation, which is assessed by pollen supplementation experiments. In a pollen supplementat...

Background and aims: As most plants rely on pollination for persistence in communities, pollination interactions should be important determinants of plant community assembly. Here, trait and phylogenetic null modelling approaches were combined with pollinator interaction networks to elucidate the processes structuring flower colour assembly patter...

Non‐native plants often alter environments they invade, favouring their own performance through positive feedbacks. Plant–soil interactions represent one such mechanism, but their complexity (e.g. invader‐induced changes in soil nutrients, microbial communities, etc.) makes inferences of the precise mechanisms that benefit invaders difficult. Here...

Background The evolution of reproductive isolation between herbivorous insect populations is often initiated by shifts to novel host-plants, a process that underlies some of the best examples of ecological speciation. However, it is not well understood why host-shifts occur. Arguably the most common hypothesis is that host-shifts occur in response...

Explaining the variation in diversification rate across groups of plants has long been an important goal of botanists. In plants, complex scenarios involving a combination of extrinsic opportunities and intrinsic traits have been used to explain rapid diversification in certain groups. However, we feel that a very simple trait has been neglected fr...

Background and aims: The ability to fix atmospheric nitrogen is thought to play an important role in the invasion success of legumes. Interactions between legumes and nitrogen-fixing bacteria (rhizobia) span a continuum of specialization, and promiscuous legumes are thought to have higher chances of forming effective symbioses in novel ranges. Usi...

Interactions between non‐native plants and their mutualists are often disrupted upon introduction to new environments. Using legume–rhizobium mutualistic interactions as an example, we discuss two pathways that can influence symbiotic associations in such situations: co‐introduction of coevolved rhizobia; and utilization of, and adaptation to, resi...

Rooibos tea, Aspalathus linearis (Burm.f.), represents one of South Africa's most important indigenous crops, and monotypic plantations are rapidly replacing wild populations. Dwindling wild rooibos populations may drastically reduce possible, but hitherto overlooked, natural resources to bolster commercial productivity and long-term sustainability...

Globally plant species richness is a significant predictor of insect richness. Whether this is the result of insect diversity responding directly to plant diversity, or both groups responding in similar ways to extrinsic factors, has been much debated. Here we assess this relationship in the Cape Floristic Region (CFR), a biodiversity hotspot. The...

Individual-based accumulation curve constructed for (A) autumn and (B) spring. Fitted curves are based on locally weighted scatterplot smoothing (LOESS). (DOCX)

Rarefaction curves for all sites, based on a combination of the two sampling seasons and using plots as units. (DOCX)

Rarefaction curves for all squares, based on a combination of the two sampling seasons and using plots as units. (DOCX)

Means and ranges for Bioclim variables are shown for each of the three mountains. Other Bioclim variables showed no variation. The extremely low variation within and between mountains suggest that broad climatic factors are similar between mountains. (DOCX)

Rarefaction curves for (A) the entire region and (B) all mountains, based on a combination of the two sampling seasons and using plots as units. (DOCX)

Rarefaction curves for all clusters, based on a combination of the two sampling seasons and using plots as units. (DOCX)

The Greater Cape Floristic Region (GCFR) in South Africa has been extensively investigated for its phenomenal angiosperm diversity. A key emergent pattern is the occurrence of older plant lineages in the southern Fynbos biome and younger lineages in the northern Succulent Karoo biome. We know practically nothing, however, about the evolutionary his...

Recent work has suggested that emergent ecological network structure exhibits very little spatial or temporal variance despite changes in community composition. However, the changes in network interactions associated with turnover in community composition have seldom been assessed. Here we examine whether changes in ecological networks are best det...

Global synthesis indicates that limitation of plant fecundity by pollen receipt (pollen limitation) is positively related to regional plant diversity and is higher for self-incompatible than self-compatible species. While self-incompatible species are always dependent on pollinating agents, self-compatible species may be pollinator-dependent or aut...

Establishing mutualistic interactions in novel environments is important for the successful establishment of some non-native plant species. These associations may, in turn, impact native species interaction networks as non-natives become dominant in their new environments. Using phylogenetic and ecological interaction network approaches we provide...

Patterns of niche partitioning can result from local ecological interactions (e.g. interspecific competition) occurring within a contemporary time frame (realized niche partitioning). Alternatively, they may represent the end product of historical processes acting over long time frames (fundamental niche partitioning). Niche partitioning is often d...

Dispersal and dormancy are important risk‐reducing strategies in unpredictable environments. Negative covariation between these strategies is theoretically expected, but empirical evidence is limited and inconsistent. Moreover, covariation may be affected by other life‐history traits and may vary across levels of biological organization. We assesse...

Plant species that occur together, flower at the same time and have the same pollinators may interact by competing for visits, facilitating visits or interfering with each other's pollination through heterospecific pollen transfer (HPT).

Extreme long-distance dispersal is an important process in plant biogeography. Such events can lead to rapid diversification due to founder effects, genetic drift and novel selection in recipient environments. Balloon vines (Cardiospermum spp.) are mainly Neotropical, but include two native southern African species, the endemic desert-adapted C. pe...

Most sedentary marine animals disperse from their place of origin during their initial life stages as larvae. The delivery of planktonic larvae back to coastal adult habitats after weeks or months of offshore development is commonly thought to be stochastic, resulting in large recruitment fluctuations and making predictive understanding of populati...

Since co‐flowering plants often share pollinators, their fecundity is likely affected by pollen transfer within and among plant species. Changes in pollinator visitation rates (e.g. through facilitation or competition for pollinators) are usually thought to exert the predominant influence on plant fecundity. However, the transfer of conspecific rel...

Aim A key aspect of effective invasive plant management is a clear understanding of natal ranges. In the balloon vine genus, Cardiospermum , uncertain native biogeographic ranges are hampering ongoing biological control efforts against invasive taxa in southern Africa. With the objective of minimizing non‐target impacts, which are a major concern f...

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During a study to investigate the diversity of rhizobia associated with native legumes in South Africa's Cape Floristic Region, a Gram-negative bacterium designated VG1CT was isolated from the root nodules of Aspalathus abietina Thunb. Based on phylogenetic analyses of the 16S rRNA and the recA genes, VG1CT belongs to the genus Burkholderia, with t...

The Cape Floristic Region (CFR) has exceptionally high plant diversity, but because there are so few studies on insect diversity and diet breadth, little is known about the relationship between plant and insect diversity. One possibility is that plant and insect diversity in the CFR are linked through host specialisation. Alternatively, the nutrien...

Members of the balloon vine genus, Cardiospermum, have been extensively moved around the globe as medicinal and horticultural species, two of which are now widespread invasive species; C. grandiflorum and C. halicacabum. A third species, C. corindum, may also have significant invasion potential. However, in some regions the native status of these s...

A molecular phylogeny of the mainly South African genus Gorteria is presented for the first time, based on Bayesian inference and parsimony analyses using DNA sequences from plastid trnL-F and from nuclear ETS and ITS regions. It is shown that the genus is strongly paraphyletic in relation to one subgroup of Hirpicium, a finding that changes the pr...