Allen Herre
Smithsonian Institution, Evolutionary Ecology, Faculty Member
The fig and pollinator wasp obligate mutualism is diverse (~750 described species), ecologically important, and ancient (~80-90 Ma), providing model systems for generating and testing many questions in evolution and ecology. Once thought... more
The fig and pollinator wasp obligate mutualism is diverse (~750 described species), ecologically important, and ancient (~80-90 Ma), providing model systems for generating and testing many questions in evolution and ecology. Once thought to be a prime example of strict one-to-one cospeciation, current thinking suggests that genera of pollinator wasps coevolve with corresponding subsections of figs, but the degree to which cospeciation or other processes contributes to the association at finer scales is unclear. Here we use genome-wide sequence data from a community of Panamanian strangler figs (Ficus subgenus Urostigma, section Americana) and associated fig wasp pollinators (Pegoscapus spp.) to infer the process of coevolutionary diversification in this obligate mutualism. Using a model-based approach adapted from the study of gene family evolution, our results indicate pervasive and ongoing host switching of pollinator wasps at this fine phylogenetic and regional scale. Although th...
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SUMMARYThe natural history of fig-pollinating wasps and their associated species-specific nematodes allows the measurement of many parameters which are relevant to testing hypotheses concerning host-parasite ecology and evolution. Within... more
SUMMARYThe natural history of fig-pollinating wasps and their associated species-specific nematodes allows the measurement of many parameters which are relevant to testing hypotheses concerning host-parasite ecology and evolution. Within fig wasps species, it is possible to estimate lifetime reproductive success of foundress wasps as a function of presence or absence of nematode parasitism (virulence). Across species, there is a wide range of host population structures which, in turn, results in a range of opportunities for either horizontal or vertical nematode transmission. Therefore, estimates of virulence can be related to opportunities for transmission across a group of closely related hosts and their parasites. Further, the dynamics of the nematode infections over ecological and short-term evolutionary timescales can be monitored, giving added insight into the interpretation of the virulence estimates. Moreover, several scales of longer term evolutionary relationships are eith...
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Abstract For 18 species of Panamanian Ficus, representing both basal (Pharmacosycea; 4 spp.) and derived (Urostigma, Americana; 14 spp.) sections, we sampled multiple individuals per species and analyzed sequence data from multiple (3)... more
Abstract For 18 species of Panamanian Ficus, representing both basal (Pharmacosycea; 4 spp.) and derived (Urostigma, Americana; 14 spp.) sections, we sampled multiple individuals per species and analyzed sequence data from multiple (3) genetic markers (tpi, g3pdh, ...
Research Interests: Genetics, Phylogenetics, Coevolution, Speciation, Symbiosis, and 15 moreTaxonomy, Hybridization, Mutualism, Phylogeny, Models, Sampling design, Pollinators, Gene, Gen, Sympatry, Allele, Loci, Locus, Haplotype, and Woody plant
Research Interests: Speciation, Taxonomy, Nematology, Morphology, Evolution, and 6 moreMorphometry, Adaptive Radiation, Transmission, Parasite, PEST, and Keys
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Parasitodiplogaster species associated with Ficus maxima were surveyed at the Smithsonian Tropical Research Institute, Barro Colorado Island, Panama. Phase B-D syconia were collected from different trees and dissected in distilled water.... more
Parasitodiplogaster species associated with Ficus maxima were surveyed at the Smithsonian Tropical Research Institute, Barro Colorado Island, Panama. Phase B-D syconia were collected from different trees and dissected in distilled water. Because there were different nematode stomatal and male morphotypes observed in a single sycone, nematodes isolated from each fig were observed to determine general morphotype class and stored individually in DNA extraction buffer for accurate morpho/molecular pairing. Additional voucher nematodes were gently heat-treated and fixed in formalin and processed into permanent mounts in dehydrated glycerin for more rigorous morphological examination. The survey yielded two different Parasitodiplogaster species: P. maxinema and P. pharmaconema n. sp. Several morphological characters, e.g., two long and stick-like teeth in the metastegostom, and stomatal dimorphism (presence of eurystomatous form) which were not previously described, were observed in P. maxinema and are ascribed hereto this species. Parasitodiplogaster pharmaconema n. sp. is morphologically similar to P. maxinema and P. yoponema but can be distinguished from these species based upon stomatal morphology, spicule and gubernaculum morphology, and number and arrangement of male genital papillae.
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Research Interests: Speciation, Taxonomy, Nematology, Morphology, Evolution, and 6 moreMorphometry, Adaptive Radiation, Transmission, Parasite, PEST, and Keys
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ABSTRACT
Research Interests: Phylogeography, Pollination, Peru, Costa Rica, Multidisciplinary, and 13 morePanama, Phylogeny, Wasps, Pollen, Animals, Forests, Ficus, PLoS one, Seedlings, Figs, Seeds, Figs and Wasps, and Moraceae
Ticks are important vectors of emerging zoonotic diseases. While adults of many tick species parasitize mammals, immature ticks are often found on wild birds. In the tropics, difficulties in species-level identification of immature ticks... more
Ticks are important vectors of emerging zoonotic diseases. While adults of many tick species parasitize mammals, immature ticks are often found on wild birds. In the tropics, difficulties in species-level identification of immature ticks hinder studies of tick ecology and tick-borne disease transmission, including any potential role for birds. In Panama, we found immature ticks on 227 out of 3,498 birds representing 93 host species, about 1/8th of the entire Panamanian terrestrial avifauna. Tick parasitism rates did not vary with temperature or rainfall, but parasitism rates did vary with host ecological traits: non-migratory residents, forest dwelling birds, bark insectivores, terrestrial foragers and lowland species were most likely to be infested with ticks. Using a molecular library developed from adult ticks specifically for this study, we identified 130 immature ticks obtained from wild birds, corresponding to eleven tick species, indicating that a substantial portion of the P...
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Syconia (enclosed infructescences) infested with host-specific species of Schistonchus (Aphelenchoididae) were collected from six species of Ficus (Moraceae) native to Florida or Panama. They were sectioned and histologically examined to... more
Syconia (enclosed infructescences) infested with host-specific species of Schistonchus (Aphelenchoididae) were collected from six species of Ficus (Moraceae) native to Florida or Panama. They were sectioned and histologically examined to assess the effects of parasitism. Parasitism by Schistonchus spp. was associated with hypertrophied cells, tissue necrosis, and the presence of an exudate in all species. Occasional hypertrophy of the outer epidermal cells occurred on seed florets, wasp florets, and on the endothecial cells of male florets in F. aurea (subgenus Urostigma) from Florida. Aberrations of the inner mesocarp occurred under the hypertrophied cells on seed florets. In F. laevigata (subgenus Urostigma) from Florida, Schistonchus sp. infested immature male florets and was associated with hypertrophy of endothecial cells, epidermal cells of the anther filaments, and anthers. Schistonchus sp. also caused aberrations of the anther filament, anthers, and pollen. Ficus poponoei (s...
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Mutualisms are of fundamental importance in all ecosystems but their very existence poses a series of challenging evolutionary questions. Recently, the application of molecular analyses combined with theoretical advances have transformed... more
Mutualisms are of fundamental importance in all ecosystems but their very existence poses a series of challenging evolutionary questions. Recently, the application of molecular analyses combined with theoretical advances have transformed our understanding of many specific systems, thereby contributing to the possibility of a more general understanding of the factors that influence mutualisms.
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ABSTRACT Background/Question/Methods Foliar fungal endophytes are abundant and diverse in the leaves of tropical plants. Their presence can reduce herbivory and pathogen damage. However, factors affecting the species composition of... more
ABSTRACT Background/Question/Methods Foliar fungal endophytes are abundant and diverse in the leaves of tropical plants. Their presence can reduce herbivory and pathogen damage. However, factors affecting the species composition of fungal- host assemblages are poorly understood. Previous studies often do not adequately control for confounding effects of local site (source pool of fungal spores), leaf age, light regime, or host species attributes on relative abundances of endophyte species across different host plant species. In order to address these questions, we studied the colonization and diversity of endophytic fungi associated with eight host plant species growing intermixed over 18 months in a common garden under high and low light regimes in the Barro Colorado Nature Monument. Results/Conclusions We found that the identities and relative abundance of dominant endophyte species varied across different host species. Endophyte diversity decreased with increasing leaf age, suggesting succession of the fungal communities within each leaf. We also found dramatic differences in culturable endophyte abundances across host plants species and across study years. Endophyte abundance but not diversity varied with light environment, with the response to light environment differing across plant host species. Endophyte abundance was negatively correlated with maximum photosynthesis rate and leaf toughness, but no relationship was observed between endophyte abundance and nitrogen content, insect herbivory or phenolic content. We discuss how host plant life-history trade-offs, local source pools of fungal spores, and light regimes may affect the relationships among tropical host plants and their fungal symbionts.
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Parasitodiplogaster species that are associated with figs in the Ficus subsection Pharmacosycea, i.e., Ficus maxima, F. yoponensis, F. insipida and F. glabrata, were studied using morphological characters and molecular sequences. Some... more
Parasitodiplogaster species that are associated with figs in the Ficus subsection Pharmacosycea, i.e., Ficus maxima, F. yoponensis, F. insipida and F. glabrata, were studied using morphological characters and molecular sequences. Some nematodes isolated from the fig sycones were casually observed and recorded as morphospecies according to their morphotype, and were then digested for their DNA, while others were fixed in formalin-glycerin for additional morphological study. High resolution microscopic observation of the morphological materials yielded five morphospecies including two nominal species, P. maxinema and P. pharmaconema. The morphospecies were distinguished from each other by male tail characters. By contrast, five and six genotypes were recognised by D2/D3 expansion segments of the large subunit (LSU) and near-full-length sequences of small subunit (SSU) ribosomal RNA genes, respectively. Except for two nominal species, genotypes and morphospecies were not clearly correl...
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Page 224. CHAPTER EIGHT An overview of arbuscular mycorrhizal fungal composition, distribution and host effects from a tropical moist forest EDWARD ALLEN HERRE AND DAMOND KYLLO Smithsonian Tropical Research ...
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The effects of inbreeding and local mate competition have often been confounded in theoretical and empirical studies of sex ratio. A general model considering the interplay of their influences on sex ratio evolution is presented, and its... more
The effects of inbreeding and local mate competition have often been confounded in theoretical and empirical studies of sex ratio. A general model considering the interplay of their influences on sex ratio evolution is presented, and its predictions are compared with data collected from three fig wasp species. The results indicate that female fig wasps adjust the sex ratio of their offspring in response to both the intensity of proximate local mate competition and the level of inbreeding in the population.
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Page 1. doi: 10.1098/rspb.2000.1418 , 685-694 268 2001 Proc. R. Soc. Lond. B Allen Herre Carlos A. Machado, Emmanuelle Jousselin, Finn Kjellberg, Stephen G. Compton and Edward character evolution of fig-pollinating wasps ...
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Damping-off was observed on experimentally planted seedlings of Ana-cardium excelsum (wild cashew), a timber tree, and Tetragastris panamensis, a canopy tree, within lowland tropical rain forest in Panama. Disease impact was greatest... more
Damping-off was observed on experimentally planted seedlings of Ana-cardium excelsum (wild cashew), a timber tree, and Tetragastris panamensis, a canopy tree, within lowland tropical rain forest in Panama. Disease impact was greatest during the wet season (May through December). During the 1995 wet season, 40.7% (572/1,404) of T. panamensis seedlings died due to damping-off disease. Sixty-eight percent (703/1,034) of A. excelsum seed lings died due to damping-off during the 1996 wet season. Symptoms included leaf, cotyledon, and stem necrosis. Phytophthora heveae sporangia were observed on both host species, and oospores were found within stems of T. panamensis. Plating of diseased A. excelsum seedlings on potato dextrose agar with rifampicin (25 mg/ml) and pimaricin (10 mg/ml) produced cultures of Phytophthora heveae and Pythium from 27.4% (110/402) and 44.5% (179/402) of seedlings, respectively. Pythium isolates included P. vexans, P. splendens, and P. chamaehyphon species types, ...
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Figs are completely dependent for pollen dispersal on species-specific fig-pollinating wasps that develop within developing fig fruits. These wasps are very sensitive to heat and die at temperatures only a few degrees above ambient. Such... more
Figs are completely dependent for pollen dispersal on species-specific fig-pollinating wasps that develop within developing fig fruits. These wasps are very sensitive to heat and die at temperatures only a few degrees above ambient. Such temperatures are expected and observed in objects exposed to full sunlight, as fig fruits frequently are. In detailed field and experimental studies of 11 species of Panamanian figs with fruit ranging in size from 5 mm to 50 mm in diameter, we found that both the relative and absolute contribution of transpiration to maintaining non-lethal fruit temperatures increased with fruit size. Small and large fruits reached temperatures of 3 and 8°C, respectively, above air temperature in full sunlight when transpiration was prevented by grease. The temperature reached by large, nontranspiring fruits was sufficient to kill their pollinators. Control fruits which transpired reached temperatures of 2-3°C above air temperature in sunlight, regardless of size. An analysis of the solar energy budget of fruit revealed that large fruits must transpire to maintain tolerable temperatures for the wasps because heat diffusion from fruit to air was too low to balance net radiation in sunlight. By contrast, small fruits do not need to transpire to maintain tolerable temperatures for the pollinators.