As you weed, so shall you reap: on the origin of algaculture in damselfish

Within their territories, damselfish cultivate particular algae for consumption. A recent study in BMC Evolutionary Biology shows extensive variation among and within fish species in the composition of these algal 'gardens', varying from monocultures to cultures of mixed species, and in the mode of cultivation. This fish-algal agriculture may provide insight into the early stages of domesticatio

Species and speciation in the Hebeloma crustuliniforme complex.

This thesis deals with species delimitation and speciation in the ectomycorrhizal Hebeloma crustuliniforme complex. The species concept traditionally used in this complex is based on morphology of basidiocarps. However, species delimitation has been controversial. One of the best known names is H. crustuliniforme (Bull.) Quél., a name regularly encountered in the mycorrhizal literature. However, this name has been used for a species complex of taxa with relatively pale (but sometimes more brown-tinged), veilless carpophores with weeping lamellae. In this thesis the basal criterion to delimit species within the Hebeloma crustuliniforme complex is sexual intercompatibility. Therefore, speciation is here defined as the origin of sexual interincompatibility. The strategy that has been used in this thesis to address the questions of species delimitation and speciation in the Hebeloma crustuliniforme complex can be summarized as follows:Define InterCompatibility Groups (ICGs) and look for examples of partial incompatibility (Chapter 2);Determine phylogenetic relationships between those ICGs (Chapter 3);Focus on closely related, and preferentially partially incompatible, ICGs to study speciation (Chapters 4, 5);Derive an operational species concept for the Hebeloma crustuliniforme complex that is based on morphological recognition of (combinations of) biological species within an explicitly phylogenetic framework (Chapter 6).In Chapter 2 the results are described of intercompatibility tests in this species complex. In a sample of 110 collections 20 InterCompatibility Groups (ICGs) were found. Partial compatibility was found between ICGs 3 and 4, between 2 and 3/4, between 1 and 2 and between 16 and 17. One strain (605) was compatible with all strains of ICGs 3 and 4. In all other cases, however, assignment of isolates to a single ICG was unambiguous. Individual compatible combinations between members of the partially compatible ICG 1 and 2 and between members of the partially compatible ICG 16 and 17 showed signs of reduced compatibility. This was reflected by: (i) no or unidirectional nuclear migration, (ii) reduced growth rate of the dikaryon and (iii) aberrant morphology of hyphae.In Chapter 3 phylogenetic relationships were studied between the ICGs of the H. crustuliniforme complex and between them and the other main groups in the genus Hebeloma based on nuclear ribosomal ITS sequences, using cladistic methods. The 20 ICGs of the H. crustuliniforme complex do not form a monophyletic group, but instead form two distinct clades, one consisting of three ICGs (clade I) and the other of 17 ICGs (clade II). Most of the ICGs in the latter clade were very closely related as suggested by a low sequence divergence. The majority of ICGs of this clade showed a preference for Salicaceae , but the basal ICG (ICG 21) did not. The host tree switch to Salicaceae has probably been followed by extensive and rapid speciation.Several other well supported clades were found in the genus Hebeloma , but the basal relationships between them were not well resolved. It is therefore impossible to propose a new infrageneric division for Hebelama .In Chapter 4 a subclade of clade II (subclade IIa) was studied in detail. In this subclade nine ICGs were found, four of which were partially compatible. This partial intercompatibility was organised hierarchically with an intermediate level of compatibility between ICGs 3 and 4 and very limited compatibility between 2 and 3/4 and between 1 and 2. The single strain (605) that was intercompatible with all strains of ICGs 3 and 4 was a member of subclade IIa as well. A mitochondrial and a nuclear phylogeny of strains belonging to these partially compatible populations were reconstructed. For ICGs 2, 3 and 4 a positive correlation was found between the level of interincompatibility and the relative age of the most recent common ancestor. ICGs generally formed monophyletic groups, ICG 3 and 4 (15% partial intercompatibility) together formed a monophyletic group and the sister group of (3,4) was ICG 2 (0.4% intercompatible with (3,4)). This is consistent with a gradual origin of sexual incompatibility (divergence-first). ICG 1 had a different position in the nuclear and mitochondrial phylogeny. In the nuclear phylogeny it was the sister taxon of ICG 5, and in the mitochondrial the sister group of ICG 2. A possible explanation is that ICG 1 has a hybrid origin, with the ancestor of ICG 5 as the nuclear donor and the ancestor of 2 as the mitochondrial donor.The subject of Chapter 5 is a polymorphism in the ribosomal Internal Transcribed Spacer of ICG 17. Within this ICG of the morphospecies Hebeloma velutipes a dikaryotic strain (d504) was found with two divergent types ITS. These two types segregated in monokaryotic progeny of the same strain, showing that the different ITS types represent different alleles at homologous rDNA loci. RFLP analysis of more strains of ICG 17 showed that the polymorphism is widespread, with both types occurring in Europe as well as in America. Cladistic analyses of the two ITS sequences showed that they did not form a monophyletic group. One of the types belonged to a clade together with the single ITS type found in the partially compatible ICG 16 and the other to a clade together with the single ITS type found in the fully incompatible ICG 18. RFLP analysis of the mitochondrial ribosomal SSU showed that there were fixed differences between the mitochondria of ICG 16 and 17. Several lines of evidence were described that the ITS polymorphism in ICG 17 is not the result of actual hybridisation between 16 and 17. The polymorphism within ICG 17 must therefore be of a different origin. The lack of recombinants, neither within the rDNA locus nor between ITS 1 and 2, suggests that the two types have come together relatively recently. The ITS polymorphism described in this Chapter clearly showed the potential danger of using single ribosomal sequences for reconstructing species phylogenies and the potential problems for molecular identification of species.In Chapter 6 a method is presented to derive an operational species concept for the Hebeloma crustuliniforme complex that is based on (combinations of) biological species within an explicitly phylogenetic framework. Crucial in this analysis is a reliable estimate of the phylogeny of biological species in the H. crustuliniforme complex. Based on two nuclear sequences, we presented a best estimate of the phylogeny of biological species within the H. crustuliniforme complex. Using this phylogeny, on the basis of (strict) monophyly only two species could be recognised among 20 biological species, viz. H. velutipes and H. helodes . An earlier phylogenetic analysis indicated that these two morphological species are not sister taxa. Relaxing the criterion of monophyly and allowing paraphyletic groupings of biological species as a morphospecies resulted in the recognition of three morphospecies, viz. H. velutipes , H. incarnatulum and H. helodes . A tree, with the five ICGs of the previously defined morphospecies Hebeloma crustuliniforme (1, 2, 3, 4 and 5) constrained as a monophyletic group could not be rejected. This constrained tree, together with the relaxed criterion, allowed the recognition of four species, viz. H. helodes , H. crustuliniforme , H. velutipes and H. incarnatulum . The limited ability to translate a biological species concept into an operational species concept was explained by the lack of qualitative characters and the plasticity of quantitative characters. Based on the close relationship between the ICGs in the two clades of the H. crustuliniforme complex, it was shown that a good correspondence between a biological species concept and a morphological species concept is not likely to be forthcoming.In the final Chapter the results found in this study were integrated and discussed in a broader context and directions for future research were suggested. Future phylogenetic studies should consider the possibility of genetic exchange between divergent populations more explicitly.</p

Diversity of fungus-growing termites (Macrotermes) and their fungal symbionts (Termitomyces) in the semiarid Tsavo Ecosystem, Kenya.

Fungus-growing termites of the subfamily Macrotermitinae together with their highly specialized fungal symbionts (Termitomyces) are primary decomposers of dead plant matter in many African savanna ecosystems. The termites provide crucial ecosystem services also by modifying soil properties, translocating nutrients, and as important drivers of plant succession. Despite their obvious ecological importance, many basic features in the biology of fungus-growing termites and especially their fungal symbionts remain poorly known, and no studies have so far focused on possible habitat-level differences in symbiont diversity across heterogeneous landscapes. We studied the species identities of Macrotermes termites and their Termitomyces symbionts by excavating 143 termite mounds at eight study sites in the semiarid Tsavo Ecosystem of southern Kenya. Reference specimens were identified by sequencing the COI region from termites and the ITS region from symbiotic fungi. The results demonstrate that the regional Macrotermes community in Tsavo includes two sympatric species (M. subhyalinus and M. michaelseni) which cultivate and largely share three species of Termitomyces symbionts. A single species of fungus is always found in each termite mound, but even closely adjacent colonies of the same termite species often house evolutionarily divergent fungi. The species identities of both partners vary markedly between sites, suggesting hitherto unknown differences in their ecological requirements. It is apparent that both habitat heterogeneity and disturbance history can influence the regional distribution patterns of both partners in symbiosis.Peer reviewe

The early evolution of cooperation in humans: On cheating, group identity and group size

The evolution of cooperation is difficult to understand, because cheaters — individuals who profit without cooperating themselves — have a benefit in interaction with cooperators. Cooperation among humans is even more difficult to understand, because cooperation occurs in large groups, making cheating a bigger threat. Restricting cooperation to members of one’s own group based on some tag-based recognition of non-group members (allorecognition) has been shown to stabilise cooperation. We address how spatial structure and group size affect the opportunities for cheating such tag-based cooperation in a spatially explicit simulation. We show that increased group diversity, under conditions of limited dispersal, reduces the selective opportunities for cheaters. A small number can already be sufficient to keep cheating at a low frequency. We discuss how marginal additional benefits of increased group size, above the benefits of local cooperation, can provide the selective pressure to reduce the number of group identities and discuss possible examples

Ontology population from web product information

With the vast amount of information available on the Web, there is an increasing need to structure Web data in order to make it accessible to both users and machines. E-commerce is one of the areas in which growing data congestion on the Web has serious consequences. This paper proposes a frame- work that is capable of populating a product ontology us- ing tabular product information from Web shops. By for- malizing product information in this way, better product comparison or recommendation applications could be built. Our approach employs both lexical and syntactic matching for mapping properties and instantiating values. The per- formed evaluation shows that instantiating consumer elec- Tronics from Best Buy and Newegg.com results in an F1 score of approximately 77%

The functional implications of Termitomyces domestication on fungus-growing termite gut microbiomes

Patients with chronic or recurrent otitis media with effusion who do not respond to treatment with conventional ventilation tubes are often treated with long-term ventilation tubes. The aim of this retrospective study was to determine the extrusion and complication rates of long-term ventilation tubes. The median ventilation time of the tubes was 31.5 months. The most common complication was otorrhoea. One episode of otorrhoea occurred after 24% of all tube insertions, and recurrent otorrhoea occurred in 29%. A persisting perforation developed in 19% after extrusion or removal of the tube. Other, mostly minor, complications occurred in 36% with the tube in situ and in 3% after extrusion or removal of the tube. Long-term ventilation tubes provided prolonged ventilation of the middle ear, but also resulted in a considerable number of complications. For each individual case, one should therefore determine whether the advantages of long-term ventilation tubes outweigh the possible complications in view of the available alternatives for middle ear ventilation