OpenUCT :: Browsing by Author "Hedderson, Terry A"

Browsing by Author "Hedderson, Terry A"

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Open Access
Assessment of the current population status, genetic diversity and phylogenetic affinities of the rare South African moss, Zygodon leptobolax
(2006) Wheat, Nicola M; Hedderson, Terry A
The rare moss Zygodon leptobolax is endemic to Table Mountain, where it is found growing on alien Quercus hosts. The present study aims to investigate this species, place it within a phylogenetic framework and answer the key questions I) what is the current status of Z. leptobolax? 2) what level of genetic diversity exists in the remaining populations? and 3) should these populations be afforded conservation status?
Open Access
Bryophyte diversity patterns in a fragmented landscape : a case study of South African West Coast renosterveld
(2006) Rugengamanzi, Nkubana Felecian; Hedderson, Terry A
This study examines the effects of fragmentation on bryophyte diversity in renosterveld vegetation of South Africa's west coast. The main objectives of this study are to; Document bryophyte species assemblages in remnant fragments of renosterveld vegetation, investigate the effect of fragment size, isolation and heterogeneity on bryophyte diversity patterns in renosterveld, determine the extent to which fragments are nested and evaluate the extent to which existing conservation measures are appropriate for the long-term survival of the bryophyte flora in this vegetation type. Seventy-two bryophyte species were recorded from 23 fragments ranging from 0.1 to 102 hectares.
Open Access
Bryophytes in the hydrological cycle and climate change implications : A case study of La Réunion cloud forest
(2012) Cardoso, Anabelle Williamson; Hedderson, Terry A; Ah-Peng, Claudine; Flores, Olivier; West, Adam
Bryophytes are able to intercept atmospheric water over the entire surface of their shoot and, once intercepted, this water forms a vital part of the hydrological cycle of their surrounding ecosystems. To investigate the role of bryophytes in the hydrological cycle, our study, conducted in the biodiversity hotspot of the tropical montane cloud forest of La Réunion, focused on two leafy liverwort species, Mastigophora diclados and Bazzania decrescens. We evaluated liverwort biomass, water storage capacity, atmospheric or cloud water interception, and photosynthetic response to desiccation. We found that B. decrescens stored approximately double the mean and maximum litres of water per hectare despite occupying less than half the volume of M. diclados. Despite this decreased water storage capacity, we found that M. diclados had a greater ability to intercept atmospheric moisture than B. decrescens, which had similar interception ability to the control. These interception abilities affected water flux in the two liverwort species. We found that this variation in water flux had an effect on photosynthesis. Both species displayed a significant relationship between photosynthesis and water content. We found that both species showed a loss of photosynthesis at very low and very high water contents with the optimal water content for photosynthesis corresponding to the in situ water content of the liverworts. The abundance of both species and their cloud water interception ability together with the wide range of photosynthetic tolerance of M. diclados and the large water storage capacity and slow desiccation rate of B. decrescens make both liverwort species ecologically important in the forest's hydrological cycle. Anthropogenic climate change threatens this ecosystem as the cloud that these species are so dependent on is predicted to lift. Our findings tie the liverworts very closely to their environment and therefore show support for the idea that bryophytes are excellent early warning signals for predicted climate changes.
Open Access
Determinants of gemmae output in the liverwort Lophozia ventricosa
(2004) Algar, Natalie; Söderström, Lars; Hedderson, Terry A
The spacial variation and population parameters affecting gemmae output of a boreal and arctic liverwort species, Lophozia ventricosa, were studied in Trnndelag, a boreal region of central Norway and in the arctic tundra on Svalbard. The population parameters investigated included colony size, colony shoot density, number of gemmae per shoot, proportion of gemmiferous shoots and gemmiferous shoot density. The gemmae output in a colony was calculated as the product of the number of gemmae per shoot, colony size and gemmifeorus shoot density. A Nested Analysis of Variance was used to partition population parameters spacially and a Pearsons Product-Moment Correlation was used to evaluate which of these population parameters affect gemmae output in a colony. The number of gemmae per shoot differed significantly between areas, populations and colonies, and was significantly varied between populations and colonies on Svalbard. No significant variation in the number of gemmae per shoot was found in Trnndelag. Population influences on shoot density, gemmiferous shoot density and gemmae output were significant in Trnndelag. This was expected, as more shoots in a colony is thought to influence gemmiferous shoot density and gemmae output. In Trnndelag, the only significant relation that can explain gemmae output is colony size whereas on Svalbard, gemmae output in a colony is affected by colony size, shoot density and number of gemmae per shoot. The results indicate that most of the variation in gemmae output occurs at the population level and that gemmae output differs between the arctic and boreal regions.
Open Access
The diversity of ground bryophyte communities along an altitudinal gradient on La Réunion island
(2011) Lane, Wade Howard; Hedderson, Terry A; Ah-Peng, Claudine; Slingsby, Jasper A
Aim: To compare the α, β and phylogenetic diversity of the ground bryophyte communities along a tropical altitudinal gradient in order to determine which processes govern these assemblages. Location: La Réunion island (55°39'E; 21 °00'S), in the western Indian Ocean. Methods: The ground bryophyte communities were surveyed along the eastern slope of Piton des Neiges (350 - 3050 m). α, β and phylogenetic diversity along the altitudinal gradient was determined and graphically presented. Results: The α diversity had two distinct peaks at 1150 - 1350 m and at 2750 m, these corresponded to a dominance in liverwort and moss species, respectively. The phylogenetic diversity along the altitudinal gradient was far greater than is predicted from the null models suggesting that ground bryophyte communities are structured according to "environmental filters". The mid-domain effect and mass effect could not be used to describe the changing diversity along the altitudinal gradient, however a correlation analysis revealed temperature and relative humidity influences the changing a diversity. Main Conclusions: In conclusion both ecological and evolutionary processes structure the ground bryophyte communities.
Open Access
Evolution of life history strategies in Lophoziaceae
(2007) Manyanga, Phelex; Hedderson, Terry A; Söderström, Lars
This study used data from literature and data from the field to analyse the patterns of variation in life history characters among members of the liverwort family Lophoziaceae. A combination of Principal Component and Cluster analyses was used to analyse data from literature in testing for recurrent suites of life history variation among species of the family. Data from literature were also used to examine the relationship between mode of reproduction and reproductive system (sexuality) and between diaspore (spore or gemma) frequency and sexuality. Data from the field were used to establish diaspore (spore and gemma) sizes and their production per capsule or shoot and to test for relationships between diaspore size and production per shoot/capsule and also between diaspore sizes and proportion of germination.
Open Access
Further studies with Melianthus L. : a molecular phylogeny, evolutionary patterns of diversification in the genus and pollinator syndromes
(2003) Henning, Jack; Verboom, George Anthony; Hedderson, Terry A
A phylogeny was produced for the eight taxa comprising the largely South African genus Melianthus L. based on two plastid markers (trnL-F and psbA-trnH) and one nuclear marker (ITS). Topological comparisons with a tree based on an existing morphological data set revealed significant incongruence leading to a loss of resolution upon combination. Ultimately, the combined three-gene data tree was selected as the strongest phylogenetic estimate for Melianthus based on its better resolution and greater support levels. This tree confirms the monophyly of Melianthus with M. major being resolved as sister to the remainder of the genus. Within the remaining clade, M. villosus is resolved sister to a clade comprising two morphologically distinct subclades, one of these being noted for a western distribution (comprising M. elongatus and the M. pectinatus complex), the other being centred farther east (comprising M. cocomosus and the M dregeanus complex). A molecular clock analysis was employed to date the emergence of specific taxa and clades, while ancestral range and habitat reconstructions were performed to determine historical conditions under which these groups and their morphological novelties arose. A scenario depicting the evolution and diversification of Melianthus is developed against a backdrop of the paleo-history of southern Africa. The genus appears to have originated in the eastern part of South Africa during a mild, mesic Oligocene with subsequent westward expansion into drier habitats of Miocene and Pliocene origins. Observations of bird visitors to a range of Melianthus species indicate that the genus employs a generalist pollination syndrome, thus refuting suggestions of a co-exclusive relationship with sunbirds (Nectariniidae). Nevertheless, the genus is undeniably ornithophilous. Nectar studies reveal interspecific variation in both the volume and concentration of nectar produced as well as in nectar colourition.
Open Access
Genetic and morphological means of differentiating within and between populations of Widdringtonia whytei and Widdringtonia nodiflora on Mount Mulanje, Malawi
(2010) Hall, Stuart; Hedderson, Terry A; February, Edmund C
There has been confusion in the past as to the taxonomy of Widdringtonia on Mount Mulanje. At present it is accepted that there are two species present. The aim of this study was to assess the level of genetic variation present across six populations of Widdringtonia whytei and Widdringtonia nodijlora on the mountain, and determine whether there are two genetically separate species present. Analysis of genetic variation included PsbA (chloroplast DNA), ITS (nuclear DNA), microsatellite and ISSR gene region markers. Out of the markers that amplified successfully, it was found that there is little genetic variation present with no differentiation between or within taxonomic groups for the gene regions analyzed. Morphometric analysis of cones and leaves grouped W. whytei and W. nodijlora separately, with a midgroup more closely associated with definite W. whytei. This compared favourably with observations of individuals from the different groups in the field. It is suggested that based on the low level of genetic variation across the mountain, W. whytei and W. nodijlora have diverged very recently from a W. nodijlora ancestor.
Open Access
Intraspecific variation and ecology of a highly restricted paleoendemic (Witsenia maura) in the south-western Cape
(2003) Gwynne-Evans, David; Hedderson, Terry A
Witsenia is a monospecific genus of the putatively basal group, the woody Iridaceae. This upright iris has extremely long black and yellow flowers ( see fig. 1) that are thought to have been pollinated by an extinct Sunbird. The role of the unusual black floral colouration is investigated as this colour is seldom associated with bird pollination. This plant typically exists in discreet and restricted populations in wet habitats in the South Western Cape (South Africa). The restricted nature of the plant is peculiar as it occurs in either low or high altitudes, yet appears to be extremely sensitive to altitude. Popular belief suggests that Witsenia maura occurs in the Peninsula only, and results from this study show the Peninsula population to be genetically separate from other populations, reflecting a long term separation. Samples from nine populations are sequenced to investigate haplotypic variation within the species, and dispersal of ancestral populations. This thesis investigates the current knowledge of Witsenia, its ecology, history and distribution. An examination of flowers under UV light reveals the first evidence of UV nectar guides in an ornithophilous flower. Conservation issues are also addressed, and it is established that although small and apparently shrinking due to global warming, populations are nonetheless viable if managed properly. A molecular study of the species and examinination of its variation revealed exceptional haplotype diversity. This diversity can best be explained by swamps acting as refugia during interglacial periods.
Open Access
Lack of polymorphism suggests a recent bottleneck of Aloidendron pillansii: Exploration into the population of Aloidendron pillansii from phylogeographical analysis of molecular data
(2014) Josephs, Randall Evan; Hedderson, Terry A; Hoffman, M T
The Karoo-Namib is a species rich region in which many iconic and keystone species are found, such as Aloe pillansii. The recent population history of A.pillansii is poorly understood. However the suggested climatic shifts that occurred throughout the Holocene era may have affected its distribution, demographics and gene flow. The glacial/interglacial refugia hypothesis predicts that the southernmost population served as a refuge population and that the subsequent expansion of the population was to the north in concert with the northward expansion of the winter rainfall regime. I evaluated this hypothesis by linking the molecular data (cpDNA and nDNA) of 84 individuals from three main populations with phylogeographical techniques. Based on the combination of percentage of mutations percentage per million years range and the chloroplast sequences, it has been estimated that the time of divergences was between 3.45 to 16.67 million years ago. The molecular analysis identified a significant lack of genetic diversity within and among the three dominant populations of A.pillansii. This suggests that the species experienced a severe bottleneck event prior to its recent expansion that has been suggested to have occurred within the time frame of 100 to 1000 years ago. This pattern is compared with its sister taxa Aloe dichtotma, which possesses variation within and among its populations. The lack of genetic variation evident within A. pillansii leaves it vulnerable to future climate shifts as low genetic variation within a species lowers the ability of that species to adapt to both environmental and climatic changes. This thesis has provided a brief insight into the population history of A.pillansii, but further research is needed.
Open Access
Molecular and morphological phylogenetic analyses of Euphorbia L. (Euphorbiaceae) with an emphasis on Southern African representatives
(2003) Mapaya, Ruvimbo Jessy; Hedderson, Terry A; Bruyns, Peter V
The genus Euphorbia is morphologically diverse and nearly cosmopolitan. Both succulent and non-succulent species are found within the genus. Succulent species are found in most arid and semi-arid areas of the world, but show their greatest concentration and diversity of form in Southern Africa especially the Cape Floristic Region. The monophyly and phylogenetic relationships of the genus Euphorbia were investigated based on morphology and on sequences of the nuclear ribosomal internal transcribed spacer (ITS) and chloroplast psbA-trnH intergenic spacer. Fifty-one species of Euphorbia and four outgroups from Monadenium and Ciutia were sampled. Matrices were analysed using parsimony and maximum likelihood methods. Separate analyses of data partitions resulted in largely non-conflicting topologies; therefore the data sets were combined. The results showed that the genus Euphorbia is paraphyletic and four monophyletic groups with a number of putative synapomorphies defining each clade were strongly supported in most analyses. The Cape succulents fall into two well-supported clades. The results thus provided evidence for Cape radiations. Most analyses indicated that one of the Cape groups is sister to a group consisting of species mostly from Southern Africa (excludingthe Cape Region). Increased taxon sampling is however needed to clarify relationships within the monophyletic groups. Morphological characters recovered broad groups within Euphorbia. Due to inadequate sampling in some sections, modifications in the present classification of Euphorbia are not suggested. The total evidence tree was used to explore morphological character evolution through character state optimisations. The presence of root tubers was homoplasious and this character state is hypothesized to have arisen at least five times under current sampling. Cylindrical stems, conspicuous leaves and absence of leaf spines were some of the pleisiomorphic states observed in some sampled members of the genus Euphorbia. Although the results obtained in the CUlTent study are preliminary, they have created further challenges for future studies of phylogenetic relationships and morphological character evolution in the genus Euphorbia.
Open Access
Molecular systematics of the leafy liverwort family Lophoziaceae cavers
(2009) De Roo, Ryan Thomas; Hedderson, Terry A; Söderström, Lars
Many recent workers have included it in Jungermanniaceae, and even in its strictest sense, internal classification has varied widely among different treatments. Here an analysis of the variation in DNA sequences of the chloroplast rps4 gene and the trnG intron provides resolution of phylogenetic relationships in the leafy liverworts with emphasis on the various elements usually placed in Lophoziaceae. The following conclusions are drawn.
Open Access
The molecular systematics of Ulva Linnaeus and Enteromorpha Link (Ulvales, Chlorophyta) from the South Western Cape, South Africa
(2002) Kandjengo, Lineekela; Bolton, John J; Hedderson, Terry A
Both Ulva and Enteromorpha are very common, ubiquitous, and environmentally important genera of green seaweeds. The evolutionary history of Ulva species is poorly understood, stemming from a lack of diagnostic, non-molecular systematic characters. This study addresses the following questions: i) Do the two genera represent distinct entitiesj ii) What are the relationships among local putative species; iii) Do the recognized species represent monophyletic lineages; iv) How closely are local species related to those from elsewhere? These questions are addressed using nuclear ribosomal DNA ITS sequences from 48 local samples plus data on 16 samples from GenBank.
Open Access
Molecular systematics, biogeography and dating of the tribe Haemantheae (Amaryllidaceae) and the phylogeography of Clivia
(2008) Conrad, Ferozah; Snijman, Dee; Hedderson, Terry A; Reeves, Gail
The African tribe Haemantheae, belonging to the monocotyledonous family Amaryllidaceae, comprises six genera (Gethyllis, Apodolirion, Haemanthus, Scadoxus, Clivia and Cryptostephanus) with ca. 90 species. A phylogenetic hypothesis for the Haemantheae is presented as a basis for an enquiry into the generic and species relationships within the tribe. DNA sequence data from five plastid regions: the rpoB-trnC intergenic spacer, trnL intron, trnL-F intergenic spacer, the rps16 intron, the psbA-trnH intergenic spacer and internal transcribed spacer region (ITS) have been collected and analysed for 62 taxa within this tribe using two outgroups within Amaryllidaceae. Combined parsimony and Bayesian analyses of the five plastid and one nuclear region indicated that Scadoxus and Haemanthus are monophyletic and resolved as sister clades to one another. The summer rainfall group of species within the genus Haemanthus is monophyletic. The genus Apodolirion is embedded within Gethyllis as has been previously suggested on morphological grounds. Both Clivia and Cryptostephanus resolved as monophyletic groups with Cryptostephanus placed as sister to Clivia. Character optimizations of 15 morphological characters were carried out and optimization of the character ‘anther number’ revealed the strongest evidence so far for not recognising the informally recognized Gethyllis ‘villosa’ group. Biogeographic analyses using the divergence/vicariance (DIVA) method were inconclusive in determining the ancestral node of Haemantheae as the phytogeographic areas occupied by the taxa were too widespread. Two methods, non parametric rate smoothing (NPRS) and a Bayesian method (implemented in BEAST) were used in the assessment of age estimates and divergence times within the Haemantheae. Due to a lack of fossil record for this group, a calibration point from Wikström et al. (2001) of 33 Ma was used, based on the split of Haemantheae and Hippeastreae. Results indicate a rapid diversification for the winter rainfall lineages of Haemanthus at around 5 Ma coinciding with the late Miocene/Pliocene and the aridification and formation of a Mediterranean-type climate in southwestern Africa. In contrast, Gethyllis reflects a gradual diversification from 20-8Ma before the onset of aridification and the establishment of the Mediterranean-type climate. Analyses of the Clivia populations reveal occasional haplotype sharing between Clivia species in those parts of the distribution range where they are sympatric. The interconnectedness of C. gardenii and C. robusta brings into question the recognition of these two entities as discrete species.
Open Access
Morphometric and molecular analysis of two distinct forms of Pseudocrossidium crinitum
(2004) Watson, Julia; Hedderson, Terry A
Two distinct forms of Pseudocrossidium crinitum (Bryophyta) exist- a form with a white hair point on the leaf, and one with a yellow hair point on the leaf. The white and yellow forms exist in similar areas, but the yellow hair point form is found on its own in arid areas. In this paper we analyse 16 morphometric variables and chloroplast and nuclear DNA molecular information to determine whether Pseudocrossidium crinitum should be separated into two species based on morphological differences. We use ANOVA, Principal components analysis and cluster analysis to analyse the morphometric data. Four significantly different morphological differences were found between the two forms. Five haplotypes were revealed from 8 samples, with only one haplotype shared amongst them. Two samples from the Cedarburg exhibit highly different DNA to the rest of the samples. Although genetic sampling was not large enough on which to base significant conclusions, we find that the two forms - are morphologically differentiated enough to separate Pseudocrossidium crinitum into two species.
Open Access
Nested clade analysis of geographic structure in the morphologically variable Themeda triandra in South Africa
(2004) Oatley, Graeme; Bond, William J; Hedderson, Terry A
The use of phylogeography in plant systems has been on the increase in recent years with the use of chloroplast DNA to detect sufficient intraspecific variation to reach significant conclusions about plant species histories, both temporally and spatially. In this study, the geographic structure and possible origin of the morphologically variable Themeda triandra is explored. The trnF - trnC and psbD - trnS gene regions of the cpDNA were used to find 12 haplotypes found in 11 populations of T. triandra that encompass the species large distributional range. A haplotype tree was constructed that showed the relationship of the 11 haplotypes (haplotype_H12 was excluded as it fell outside of the 95% confidence limit), with haplotype H6 inferred to be the ancestral haplotype. A nested clade analysis was performed with the results used to infer the geographic structure of T. triandra within South Africa. Significant results showed that there was restricted gene flow with nested clades involving the three Free State populations, indicating that there are barriers to gene flow with other haplotypes. The ancestral haplotype showed long distance colonisation, with a probable root of this colonisation being the Kruger National Park. This is the proposed point of introduction of T. triandra into South Africa, with results from this study supporting this proposal. A substantial amount of gene flow (25.49%; AMOV A) between populations is observed, with this probably being due to the widespread distribution of haplotypes H6 and H10. It is thought that T. triandra followed two migration routes within South Africa: one along the coast, with the other inland above the escarpment where populations became genetically isolated from populations below the escarpment. Further studies may look for a correlation between morphological variants of T. triandra and the cpDNA haplotypes found within the species.
Open Access
Palaeoclimatic impacts on the phylogeography of an Afro-montane liverwort: Jamesoniella colorata (Lophoziaceae )
(2004) Chase, Rachel Renee; Hedderson, Terry A
The mechanisms behind the high level of plant diversity and endemism observed in the Cape Floral Region (CFR) of South Africa have been the focus of many studies. Recently developed methods that employ DNA sequence data are making major contributions in reconstructing evolutionary histories of CFR species. Concurrently, palaeoenvironmental evidence is used increasingly to explain the impact of past climates on species ranges. This paper combines these two approaches by analysing the distribution of genetic diversity of the Afro-montane liverwort Jamesoniella colorata and associating its inferred evolutionary history with major palaeoclimatic trends in South Africa. Liverworts are generally well-suited for phylogeographical studies because they often have low dispersal rates, broad geographical ranges and long evolutionary persistence. In addition, the high among-population diversity observed in J colorata is conducive to the interpretation of significant historical events. The GIS-based bioclimatic envelope shows a strong correlation between potential habitat and the known distribution of J colorata and indicates that sampling in this study was sufficient to make accurate phylogeographical inferences. A combination of phylogeographical data and population genetics evidence suggests that populations of J colorata in the Western Cape Province have experienced range contractions into upper-montane refugia and range expansions into lower altitudes in response to warming and cooling climatic trends, respectively. These range shifts have probably taken place throughout the Quaternary glacial-interglacials cycles, , which are thought to have been influential in shaping modem patterns of diversity. In lV an attempt to assign approximate dates to the two expansion events inferred for J. colorata, an average chloroplast mutation rate was applied to the trnL-F cpDNA mismatch distribution. The results roughly place the expansions within the last glacial period, demonstrating the general accordance of the phylogeographical and palaeoclimatic data. The molecular work in this study also brought into question the taxonomic status of several specimens that showed distinctly divergent DNA sequences. Preliminary morphological inspection of the specimens revealed subtle but clear differences in leaf and stem anatomy that were once associated with J. oenops, a species synonymised with J. colorata in 1971.
Open Access
Phylogenetic relationships of the Genus Andreaea Hedw.(Andreaeceae,Bryophyta) as inferred from RPS4 and TRNL-F sequences and morphology
(2001) Chuba, David Kananga; Hedderson, Terry A
The moss genus Andreaea possesses some sporophyte features that resemble liverworts or mosses and some gametophyte features resembling only the mosses, whereas other features are unique. This thesis presents the first phylogenetic study of the genus, based on both morphological and molecular evidence. Gametophyte and sporophyte characters were utilised for cladistic analysis. Sequence data was also generated from two chloroplast gene loci, the trnL-F intergenic spacer and the coding region of the ribosomal protein S4 (rps4). Separate morphological and molecular analyses produced topologies incongruent in certain parts and congruent in others. However, their combined analysis was better supported and therefore offered a more reliable hypothesis. The inferred phylogeny supported the monophyly of the genus. However, the monophyly of most infra-generic groups was largely contradicted. The putative subgenus Chasmocalyx is monotypic with A. nivalis as the sole species, whereas A. australis and A. nitida were resolved within the more broadly circumscribed section Andreaea of subgenus Andreaea. The section Nerviae of subgenus Andreaea is more narrowly circumscribed. A. blyttii (presumed member of section Nerviae) forms a basal lineage separate from all other species and apparently should constitute another monotypic subgenus. A. wilsonii (traditional Subgenus Acroschisma) is embedded within section Andreaea of Subgenus Andreaea. A. subulata, a presumed member of the section Nerviae (Subgenus Andreaea) is included in the section Andreaea. Character state optimisation has shown that falcate leaves, possession of a leaf costae and medium sized spores are some of the pleisiotypic features within Andreaea. However, a number of phylogenetic questions, regarding infra-generic relationships of the genus still remain unanswered. Directions for further future work have been suggested.
Open Access
Phylogeny and character evolution in the Lampranthus-group (Aizoaceae-Ruschioideae)
(2001) Klak, Cornelia; Hedderson, Terry A; Linder, H P
The phylogenetic position of the Lampranthus - group (Ruschioideae, Aizoaceae), with particular emphasis on the large genus Lampranthus, was studied using morphological characters and DNA sequence from the trnL - trnF region of the chloroplast genome, the nuclear ribsomal internal transcribed space (ITS) region and the 5S non-transcribed spacer. The phylogenies 59 species in the 29 genera of succulent Aizoaceae, including two species from subfamily Mesembryanthemoideae, are presented.
Open Access
Phylogeny and codivergence in the fig-fig wasp mutualism : sycoecine and agaondid fig wasps (Chalcidoidea, Hymenoptera) associated with Ficus section Galoglychia (Moraceae)
(2008) Underhill, Jenny G; Tolley, Krystal A; Hedderson, Terry A; Van Noort, Simon
The interaction between figs and figs wasps is idealised as a classic example of coevolution through codivergence and cospeciation. Traditionally, the mutualism has been distinguished by a one-to-one ratio of host-specificity, whereby each species of fig tree (Ficlls, Moraceae) is pollinated by a unique species of fig wasp (Agaonidae, Chalcidoidea, Hymenoptera). Recent studies conclude, however, that extreme host-specificity is no longer as ubiquitous as previously considered. Nevertheless, there are many factors that are thought to constrain host-switching events and maintain, to some degree, the host specificity of both pollinating and non-pollinating fig wasps within the fig wasp community. This dissertation investigates the extent of codivergence between the host fig trees of Ficus section Galoglychia, associated agaonid pollinators and sycoecine non-pollinating fig wasps (Pteromalidae, Chalcidoidea, Hymenoptera) through cophylogenetic analysis.