Jan HrcekBiology Centre CAS · Institute of Entomology
Jan Hrcek
PhD
About
68
Publications
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Introduction
Lab Head, Institute of Entomology, Biology Centre CAS
Research Associate, Department of Zoology, University of Oxford
http://lab.hrcek.net
Additional affiliations
June 2013 - present
February 2008 - November 2012
Publications
Publications (68)
The analysis of interaction networks across spatial environmental gradients is a powerful approach to investigate the responses of communities to global change. Using a combination of DNA metabarcoding and traditional molecular methods we built bipartite Drosophila – parasitoid food webs from six Australian rainforest sites across gradients spannin...
Molecular identification is increasingly used to speed up biodiversity surveys and laboratory experiments. However, many groups of organisms cannot be reliably identified using standard databases such as GenBank or BOLD due to lack of sequenced voucher specimens identified by experts. Sometimes a large number of sequences are available, but with to...
Climate change is altering the relative timing of species interactions by shifting when species first appear in communities and modifying the duration organisms spend in each developmental stage. However, community contexts, such as intraspecific competition and alternative resource species, can prolong shortened windows of availability and may mit...
Current global changes are reshaping ecological communities and modifying environmental conditions. We need to recognize the combined impact of these biotic and abiotic factors on species interactions, community dynamics and ecosystem functioning. Specifically, the strength of predator prey interactions often depends on the presence of other natura...
Variation along environmental gradients in host-associated microbial communities is not well understood, compared to free-living microbial communities. Because elevational gradients may serve as natural proxies for climate change, understanding patterns along these gradients can inform our understanding of the threats hosts and their symbiotic micr...
Long-read sequencing is driving rapid progress in genome assembly across all major groups of life, including species of the family Drosophilidae, a longtime model system for genetics, genomics, and evolution. We previously developed a cost-effective hybrid Oxford Nanopore (ONT) long-read and Illumina short-read sequencing approach and used it to as...
Questions
Cover and biomass serve as common measures of species abundance in plant ecology. However, the underlying relationship between these two measures and its implications remain poorly understood. This makes results based on cover and biomass difficult to compare.
Locations
Wet meadow, southeast of České Budějovice, Czech Republic (48°57′ N,...
Appendix S1. Reasons why we expect the power coefficient b to be larger than 1.
Appendix S2. Reasons why we expect CV is higher for biomass, diversity is higher for cover.
Appendix S3. Sampling method of plant cover and biomass data.
Appendix S4. Picture showing the collection of plant cover data.
Appendix S5. The quadrat for relevés with a gri...
Aims
Oligotrophic grasslands are habitats that host among the most diverse plant communities in Europe. Altering management regimes by either intensifying or ceasing management is known to decrease plant diversity. Yet, despite its importance for the recovery of plant communities after disturbances, little is known about whether seed banks are also...
Over the course of evolution, hymenopteran parasitoids have developed a close relationship with heritable viruses, sometimes even integrating viral genes into their chromosomes. For example, in Drosophila parasitoids belonging to the Leptopilina genus, 13 viral genes from the Filamentoviridae family have been integrated and domesticated to deliver...
We apply a molecular approach to quantify the level of hymenopteran parasitoids infestation in the larvae of the marsh fritillary (Euphydryas aurinia), a declining butterfly species, in western Bohemia, Czech Republic, in two subsequent years. We used the novel primer HymR157 in combination with known universal 28SD1F to establish a PCR detection s...
Long-read sequencing is driving rapid progress in genome assembly across all major groups of life, including species of the family Drosophilidae, a longtime model system for genetics, genomics, and evolution. We previously developed a cost-effective hybrid Oxford Nanopore (ONT) long-read and Illumina short-read sequencing approach and used it to as...
Variation along environmental gradients in host-associated microbial communities is not well understood compared to free-living microbial communities. Because elevational gradients may serve as natural proxies for climate change, understanding patterns along these gradients can inform our understanding of the threats hosts and their symbiotic micro...
Metabarcoding is revolutionizing fundamental research in ecology by enabling large-scale detection of species and producing data that is rich with community context. However, the benefits of metabarcoding have yet to be fully realized in fields of applied ecology, especially those such as classical biological control (CBC) research that involve hyp...
Ecological communities are composed of many species, forming complex networks of interactions. Current environmental changes are altering the structure and species composition of ecological networks, which could modify interactions, either directly or indirectly. To predict changes in the functioning of communities, we need to understand whether sp...
Aim
Ecological communities are assembled by regional and local processes. These processes select species through their traits, which are tied to species' evolutionary history. A multifaceted approach, encompassing taxonomic, functional and phylogenetic diversity can thus help us to better understand community assembly. We asked what the relative im...
Current global changes are reshaping ecological communities and modifying environmental conditions. We need to recognize the combined impact of these biotic and abiotic factors on species interactions, community dynamics and ecosystem functioning. Specifically, the strength of predator-prey interactions often depends on the presence of other natura...
A molecular phylogeny of the subfamily Rogadinae is presented for 469 species in 52 genera representing all tribes and subtribes. The data comprise cytochrome c oxidase I sequences (DNA barcodes), together with a broad representation of 28S rDNA D2-D3 expansion region, EF1-α gene and 16S rDNA fragments. To test monophyly, most genera were represent...
Ecological communities are composed of many species, forming complex networks of interactions. Current environmental changes are altering community composition. We thus need to identify which aspects of species interactions are primarily driven by community structure and which by species identity to predict changes in the functioning of communities...
Climate change is altering the relative timing of species interactions by shifting when species appear in a community and by accelerating developmental rates. However, phenological shifts may be mediated through community contexts, such as intraspecific competition and alternative resource species, which can prolong the otherwise shortened windows...
Molecular identification is increasingly used to speed up biodiversity surveys and laboratory experiments. However, many groups of organisms cannot be reliably identified using standard databases such as GenBank or BOLD due to lack of sequenced voucher specimens identified by experts. Sometimes a large number of sequences are available, but with to...
Global warming is expected to have direct effects on species through their sensitivity to temperature, and also via their biotic interactions, with cascading indirect effects on species, communities, and entire ecosystems. To predict the community-level consequences of global climate change we need to understand the relative roles of both the direc...
Developmental phenotypic plasticity is a widespread phenomenon that allows organisms to produce different adult phenotypes in response to different environments. Investigating the molecular mechanisms underlying plasticity has the potential to reveal the precise changes that lead to the evolution of plasticity as a phenotype. Here, we study wing pl...
Many insects host vertically‐transmitted microbes, which can confer benefits to their hosts but are costly to maintain and regulate. A key feature of these symbioses is variation: for example, symbiont density can vary among host and symbiont genotypes. However, the evolutionary forces maintaining this variation remain unclear. We studied variation...
Current global warming trends are expected to have direct effects on species through their sensitivity to temperature, as well as on their biotic interactions, with cascading indirect effects on species, communities, and entire ecosystems. To predict the community-level consequences of global change we need to understand the relative roles of both...
A bstract
Many insects host vertically-transmitted microbes, which can confer benefits to their hosts but are costly to maintain and regulate. A key feature of these symbioses is variation: for example, symbiont density can vary among host and symbiont genotypes. However, the evolutionary forces maintaining this variation remain unclear. We studied...
The analysis of interaction networks across spatial environmental gradients is a powerful approach to investigate the responses of communities to global change. Using a combination of DNA metabarcoding and traditional molecular methods we built bipartite Drosophila-parasitoid food webs from six Australian rainforest sites across gradients spanning...
Many microbial symbionts have multiple phenotypic consequences for their animal hosts. However, the ways in which different symbiont-mediated phenotypes combine to affect fitness are not well understood. We investigated whether there are correlations between different symbiont-mediated phenotypes. We used the symbiont Spiroplasma, a striking exampl...
Microbial organisms are ubiquitous in nature, and often form communities closely associated with their host, referred to as the microbiome. The microbiome has strong influence on species interactions, but microbiome studies rarely take interactions between hosts into account, and network interaction studies rarely consider microbiomes. Here, we pro...
Invertebrate predators and parasitoids are among the most important natural enemies of insect herbivores. Yet, the strength of natural enemy pressure along an altitudinal gradient and interactions between the groups of natural enemies (such as predation on parasitized prey) are not well known. Various methods are used to reveal the mortality factor...
Questions
Species pools are the product of complex ecological and evolutionary mechanisms, operating over a range of spatial scales. Here, we focus on species absent from local sites but with the potential to establish within communities — known as dark diversity. Methods for estimating dark diversity are still being developed and need to be compar...
1. In natural communities, multiple host and parasitoid species are linked to form complex networks of trophic and non‐trophic interactions. Understanding how these networks will respond to global warming is of wide relevance for agriculture and conservation.
2. This study synthesises the emerging evidence surrounding host–parasitoid networks in th...
A new Master's study programme in Ecology (www.prf.jcu.cz/ecology) at the University of South Bohemia, will start in September 2019 with 2-years duration, the applications gate is open, deadline for applications is May 16, 2019. The programme extends a successful Quantitative Ecology Module (botanika.prf.jcu.cz/quantecol) lead by Professor Jan Lepš...
Environmental stressors can be key drivers of phenotypes, including reproductive strategies and morphological traits. The response to stress may be altered by the presence of microbial associates. For example, in aphids, facultative (secondary) bacterial symbionts can provide protection against natural enemies and stress induced by elevated tempera...
A new 2 year Masters study programme in Ecology, at the University of South Bohemia in České Budějovice, Czech Republic will start in October 2019. The programme is an extension of the successful Quantitative Ecology Module (botanika.prf.jcu.cz/quantecol) lead by Professor Jan Lepš, since 2011. Students will be trained in modern ecology research. T...
Interactions within and between species have significant effects on fitness, which are likely to vary across species ranges. However, empirical tests of this are rare, particularly under naturally varying field conditions. We transplanted 19 656 flies of two Australian tropical rainforest fly species ( Drosophila birchii and D. bunnanda ) along an...
Understanding interactions between herbivores and parasitoids is essential for successful biodiversity protection and monitoring and for biological pest control. Morphological identifications employ insect rearing and are complicated by insects’ high diversity and crypsis. DNA barcoding has been successfully used in studies of host–parasitoid inter...
Microbial symbionts commonly protect their hosts from natural enemies, but it is unclear how protective symbionts influence the evolution of host immunity to pathogens. One possibility is that ‘extrinsic’ protection provided by symbionts allows hosts to reduce investment in ‘intrinsic’ immunological resistance mechanisms. We tested this idea using...
1. Microbial symbionts can play an important role in defending their insect hosts against natural enemies. However, researchers have little idea how the presence of such protective symbionts impacts food web interactions and species diversity.
2. This study investigated the effects of a protective symbiont ( H amiltonella defensa ) in pea aphids (...
Animal-associated microbial communities have important effects on host phenotypes. Individuals within and among species differ in the strains and species of microbes that they harbour, but how natural selection shapes the distribution and abundance of symbionts in natural populations is not well understood. Symbionts can be beneficial in certain en...
Most animals host communities of symbiotic bacteria. In insects, these symbionts may have particularly intimate interactions with their hosts: many are intracellular and can play important roles in host ecology and evolution, including protection against natural enemies.
We investigated how interactions between different species or strains of endos...
Figure S1. GS x GP data, shown as a bar graph, with percent sporulation on the y‐axis.
Figure S2. GH x GS data, shown as a bar graph, with percent sporulation on the y‐axis.
Figure S3. Correlation between symbiont‐mediated protection and the costs of harboring a symbiont across Regiella genotypes.
Table S1. Information on the aphid genotypes use...
The microbial symbionts of eukaryotes influence disease resistance in many host-parasite systems. Symbionts show substantial variation in both genotype and phenotype, but it is unclear how natural selection maintains this variation. It is also unknown whether variable symbiont genotypes show specificity with the genotypes of hosts or parasites in n...
Table S1. Experimental field sites.
Fig. S1. Differences across replicates in survival of aphids carrying and not carrying symbionts (with binomial standard errors).
Fig. S2. Laboratory assays of symbiont conferred protection for strains used in the field experiment.
Fig. S3. Endosymbionts are costly under stressful laboratory conditions.
Recent research has shown that the bacterial endosymbionts of insects are abundant and diverse, and that they have numerous different effects on their hosts' biology. Here we explore how insect endosymbionts might affect the structure and dynamics of insect communities. Using the obligate and facultative symbionts of aphids as an example, we find t...
Eukaryotes commonly host communities of heritable symbiotic bacteria, many of which are not essential for their hosts' survival and reproduction. There is laboratory evidence that these facultative symbionts can provide useful adaptations, such as increased resistance to natural enemies. However, we do not know how symbionts affect host fitness whe...
Troporhysipolis gen. nov. with four included species is described and illustrated. The type species, Clinocentrus antefurcalis Granger, 1949, is Afrotropical with unknown biology. We additionally recognise three new species from eastern lowland of Papua New Guinea, T. brenthiaphagus sp. nov., T. markshawi sp. nov. and T. molecularis sp. nov., all t...
Throughout the course of their evolution, plants have acquired a wide range of chemical and mechanical defenses to protect against herbivores. Ehrlich & Raven's coevolutionary theory suggests that this diversification of defensive traits is driven by the strong impact of novel traits on insect herbivores. However, the impact of plant defenses on in...
Plant–insect food webs tend to be dominated by interactions resulting from diffuse co‐evolution between plants and multiple lineages of herbivores rather than by reciprocal co‐evolution and co‐cladogenesis. Plants therefore require defence strategies effective against a broad range of herbivore species. In one extreme, plants could develop a single...
Significance
Dietary specialization determines an organism’s resource base as well as impacts on host or prey species. There are important basic and applied reasons to ask why some animals have narrow diets and others are more generalized, and if different regions of the Earth support more specialized interactions. We investigated site-specific hos...
Quantitative food webs are valuable tools to detect patterns in community structure and generate hypotheses for experimentation. Quantitative webs of whole communities are usually not feasible to build, and most attention focuses on assemblages of species that interact in similar ways. Hosts and parasitoids are a popular guild for study, and quanti...
A new species of Cystomastacoides van Achterberg, C. asotaphaga Quicke sp. n., is described and illustrated based on a series of specimens reared from caterpillars of the erebid moth Asota plana Walker from Papua New Guinea. Two other new species without biological data are also described, C. nicolepeelerae QuickeandButcher sp. n. also from Papua N...
The processes maintaining the enormous diversity of herbivore-parasitoid food webs depend on parasitism rate and parasitoid host specificity. The two parameters have to be evaluated in concert to make conclusions about the importance of parasitoids as natural enemies and guide biological control. We document parasitism rate and host specificity in...
Microgastrine wasps are among the most species-rich and numerous parasitoids of caterpillars (Lepidoptera). They are often host-specific and thus are extensively used in biological control efforts and figure prominently in trophic webs. However, their extraordinary diversity coupled with the occurrence of many cryptic species produces a significant...
Nine new species of Colastomion Baker are described, illustrated and keyed based on series of specimens reared from caterpillars of crambid moths from lowland Papua New Guinea plus one additional field collected specimen, viz. C. cheesmanae Quicke sp. n., C. crambidiphagus Quicke sp. n., C. gregarius Quicke sp. n., C. maclayi Quicke sp. n., C. mada...
Phylogenetic ecology has identified patterns of diversity in communities that may find explanation in trophic interactions, and yet there have been few attempts to directly relate such patterns among trophic levels. Density-dependent processes involving pests and pathogens, for example, have been invoked to account for plant community phylogenetic...
Vojtechirogas novotnyi gen. nov. & sp. nov., V. heberti sp. nov. and V. wantok sp. nov. reared from Philiris helena (Snellen) (Lepidoptera: Lycaenidae) feeding on Macaranga spp., in northern lowland Papua New Guinea, are described and illustrated. Based on molecular data, on the modified vein 2-SC+R of the hind wing and the inclivous vein r-m of th...
Wolbachia is a genus of bacterial endosymbionts that impacts the breeding systems of their hosts. Wolbachia can confuse the patterns of mitochondrial variation, including DNA barcodes, because it influences the pathways through which mitochondria are inherited. We examined the extent to which these endosymbionts are detected in routine DNA barcodin...
The enormous cytochrome oxidase subunit I (COI) sequence database being assembled from the various DNA barcoding projects as well as from independent phylogenetic studies constitutes an almost unprecedented amount of data for molecular systematics, in addition to its role in species identification and discovery. As part of a study of the potential...
Classical niche theory explains the coexistence of species through their exploitation of different resources. Assemblages of herbivores coexisting on a particular plant species are thus expected to be dominated by species from host-specific guilds with narrow, coexistence-facilitating niches rather than by species from generalist guilds. Exactly th...
Previously, host-parasitoid links have been unveiled almost exclusively by time-intensive rearing, while molecular methods were used only in simple agricultural host-parasitoid systems in the form of species-specific primers. Here, we present a general method for the molecular detection of these links applied to a complex caterpillar-parasitoid foo...
The distribution of Lopinga achine (Lepidoptera Nymphalidae, Satyrinae) in the Czech Republic has declined from thirty grid squares before 1950 to just one extant population,
restricted to a single area of deciduous woodland. A review of historical sites shows that this species used to occur in various
types of deciduous woodland with a relatively...