Summary1. Foliar endophytic fungi in herbaceous plants are known to be diverse, yet studies characterizing the fungal communities in roots and shoots of plants across time are absent. These fungi are supposedly ubiquitous in nature, infecting plants through airborne spores. As many foliar endophytes can also exist in soil, we hypothesized that there would be a strong similarity between root and shoot endophytes in any given plant species and that differences between plant species would be greater than those between organs within a species. 2. Leaf and root fungal endophyte communities were assessed in field-collected plants of three co-occurring grassland forbs (Cirsium arvense, Plantago lanceolata and Rumex acetosa) in two contrasting seasons (winter and summer). The former two species are mycorrhizal, whilst the latter species is not so. 3. The highest fungal species richness was recorded from P. lanceolata with R. acetosa hosting the least endophyte diversity. Endophyte communities were more diverse in root than leaf tissues and in summer than in winter. Similarity of endophyte communities between different host plant species and organs within an individual host was very low. Negative correlations were found between mycorrhizal colonization and endophyte presence in the roots of C. arvense and P. lanceolata, suggesting some degree of antagonism or competition between the fungi. Consistent positive associations were found between the number of endophyte species in roots and shoots of plants. 4. Synthesis. In contrast to previous studies, the results show that many endophytes do not occur ubiquitously, but instead exhibit both plant and tissue specificity. There is a strong seasonal change in endophyte communities, but the differences between roots and shoots at any one time can be just as large. This dissimilarity suggests a lack of systemic growth by the fungi from one tissue to another. Mycorrhizas may interact negatively with other root endophytes, indicating that the latter should not be ignored in future mycorrhizal studies. We should begin to think of individual plants as ecosystems of interacting microbes, whose community is structured by plant genetics and environmental conditions, coupled with interactions between the microbes themselves.

To date, it has been thought that endophytic fungi in forbs infect the leaves of their hosts most commonly by air-borne spores (termed “horizontal transmission”). Here, we show that vertical transmission from mother plant to offspring, via seeds, occurs in six forb species (Centaurea cyanus, C. nigra,Papaver rhoeas,Plantago lanceolata,Rumex acetosa, and Senecio vulgaris), suggesting that this may be a widespread phenomenon. Mature seeds were collected from field-grown plants and endophytes isolated from these, and from subsequent cotyledons and true leaves of seedlings, grown in sterile conditions. Most seeds contain one species of fungus, although the identity of the endophyte differs between plant species. Strong evidence for vertical transmission was found for two endophyte species, Alternaria alternata and Cladosporium sphaerospermum. These fungi were recovered from within seeds, cotyledons, and true leaves, although the plant species they were associated with differed. Vertical transmission appears to be an imperfect process, and germination seems to present a bottleneck for fungal growth. We also found that A. alternata and C. sphaerospermum occur on, and within pollen grains, showing that endophyte transmission can be both within and between plant generations. Fungal growth with the pollen tube is likely to be the way in which endophytes enter the developing seed. The fact that true vertical transmission seems common suggests a more mutualistic association between these fungi and their hosts than has previously been thought, and possession of endophytes by seedling plants could have far-reaching ecological consequences. Seedlings may have different growth rates and be better protected against herbivores and pathogens, dependent on the fungi that were present in the mother plant. This would represent a novel case of trans-generational resistance in plants.

Zooplanktonic animals live in the open water of freshwater habitats, whilst trematodes are ubiquitous parasitic worms of aquatic vertebrates and invertebrates. A defining characteristic of trematode life cycles is the cercariae, a mainly planktonic freeliving larval stage that emerges into the aquatic environment from infected molluscan hosts. Cercariae are lecithotrophic (non-feeding) larvae analogous of meroplankton. Although millions of planktonic cercariae enter freshwater habitats on a daily basis and are capable of forming into dense clouds, they are a largely neglected component of the zooplankton community, rarely mentioned in faunal studies. Nevertheless, there is increasing evidence to suggest that cercariae have important secondary roles in aquatic food webs and energy transfer. This article reacquaints freshwater biologists with cercariae, highlighting the key characteristics of their biology and population dynamics, their role in food webs, public health and veterinary importance, and the risk of increased population densities under the influence of climate change. The reasons for their neglect in freshwater biology is evaluated and considered to be associated with zooplankton sampling methodologies being unsuitable for collecting cercariae and the paucity of identification keys in the limnological literature.

SUMMARY Temperature is an important factor influencing the biology of ectothermic organisms and is intrinsically linked to climate change. Trematodes are potentially susceptible to temperature changes and in order to develop predictive frameworks of their responses to climate change large-scale analyses are needed. The present study, using the Q 10 value, analyses experimental data from the scientific literature on the effects of temperature on cercarial development and emergence across a wide range of temperature in low (⩽35°) and mid-latitude (36-60°) species. Temperature appears to have no significant effect on the rate of development of cercariae within molluscan hosts. Data on cercarial emergence, corrected to incorporate the minimum emergence temperature threshold (METT) and acclimation status, was found to be largely unaffected by temperature over optimum ranges of ≈20 °C (15-25 °C) for mid-latitude species and ≈25 °C (20-30 °C) for low-latitude species. In addition, a decline in emergence rates was shown at higher temperatures. These results are contrary to a previous study on the meta-analysis of cercarial emergence. Some evidence of strain-specific differences and thermostability over a wide temperature range for both cercarial development and emergence was apparent. The significance of these results in furthering our understanding of cercarial biology under natural conditions is discussed.

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