scholarly journals Foliar pathogens are unlikely to stabilize coexistence of competing species in a California grassland

2017 ◽  
Author(s):  
Erin R. Spear ◽  
Erin A. Mordecai
Keyword(s):  
Seed Production ◽  
Plant Species ◽  
Relative Abundance ◽  
Host Species ◽  
Fungal Pathogens ◽  
Grassland Community ◽  
Single Host ◽  
California Grassland ◽  
Foliar Pathogens ◽  
Natural Communities

AbstractPathogen infection is common in wild plants and animals, and may regulate their populations. If pathogens have narrow host ranges and increase with the density of their favored hosts, they may promote host species diversity by suppressing common species to the benefit of rare species. Yet, because many pathogens infect multiple co-occurring hosts, they may not strongly respond to the relative abundance of a single host species. Are natural communities dominated by specialized pathogens that respond to the relative abundance of a specific host or by pathogens with broad host ranges and limited responses to the relative abundance of single host? The answer determines the potential for pathogens to promote host coexistence, as often hypothesized, or to have negligible or even negative effects on host coexistence. We lack a systematic understanding of the impacts, identities, and host ranges of pathogens in natural communities. Here we characterize a community of foliar fungal pathogens and evaluate their host specificity and fitness impacts in a California grassland community of native and exotic species. We found that most of the commonly isolated fungal pathogens were multi-host, with intermediate to low specialization. The amount of pathogen damage each host experienced was independent of host species local relative abundance. Despite pathogen sharing among the host species, fungal communities slightly differed in composition across host species. Plants with high pathogen damage tended to have lower seed production but the relationship was weak, suggesting limited fitness impacts. Moreover, seed production was not dependent on the local relative abundance of each plant species, suggesting that stabilizing coexistence mechanisms may operate at larger spatial scales in this community. Because foliar pathogens in this grassland community are multi-host and have small fitness impacts, they are unlikely to promote negative frequency-dependence or plant species coexistence in this system. Still, given that pathogen community composition differentiates across host species, some more subtle feedbacks between host relative abundance and pathogen community composition, damage, and fitness impacts are possible, which could in turn promote either coexistence or competitive exclusion.

PHYLOGENY, NICHES, AND RELATIVE ABUNDANCE IN NATURAL COMMUNITIES

Ecology ◽  
2008 ◽  
Vol 89 (4) ◽  
pp. 962-970 ◽  
Author(s):  
Colleen K. Kelly ◽  
Michael G. Bowler ◽  
Oliver Pybus ◽  
Paul H. Harvey
Keyword(s):  
Relative Abundance ◽  
Natural Communities

scholarly journals Madrigueras de Liomys pictus en dos selvas tropicales del Pacífico mexicano.

2009 ◽  
Vol 13 (1) ◽  
pp. 63 ◽  
Author(s):  
Yolanda Domínguez-Castellanos ◽  
Beatriz Hernandez Meza ◽  
Angeles Mendoza D. ◽  
Gerardo Ceballos González
Keyword(s):  
Seed Production ◽  
Tropical Forests ◽  
Plant Species ◽  
Deciduous Forest ◽  
Vegetation Type ◽  
Tropical Dry Forest ◽  
Dry Forest ◽  
Mexican Pacific ◽  
La Selva

Resumen: Se determinó la estructura y el contenido de las madrigueras de Liomys pictus por tipo de vegetación y temporada del año, en dos selvas tropicales del Pacífico Mexicano. Se encontraron 24 madrigueras: en la selva baja la mayoría son complejas, mientras que  en la selva mediana son lineales, por consiguiente y de acuerdo a la clasificación de las madrigueras, en selva baja se presentaron madrigueras múltiples y en selva mediana madrigueras simples. De acuerdo al contenido, las de selva baja tienen en promedio una mayor cantidad de materiales en comparación a las de selva mediana. Se catalogaron un total de 248 especies de plantas de estas 50 se comparten en ambos sitios, del total de las especies se llegaron a identificar sólo 77. Las familias más representativas fueron Leguminoseae, Euphorbiaceae y Convolvulaceae. La estructura de las madrigueras no esta determinada por la temporalidad, sin embargo el contenido esta determinado con la cantidad de material almacenado aunque la producción de semillas esta definido por el patrón de fructificación que esta dado a lo largo del año.Palabras clave: Madrigueras, estructura, contenido, Liomys pictus, Jalisco, México.Abstract: We determined the structure and contents of burrows of Liomys pictus by vegetation type and season in two tropical forests of the Mexican Pacific. 24 burrows were found in the tropical dry forest and most complex, in the semi deciduous forest is linear, and therefore according to the classification of the burrows in the tropical dry forest are more numerous and simple in the semi deciduous forest. According to the content, of the tropical dry forest have on average a greater amount of material compared to the semi deciduous forest. Were categorized a total of 248 plant species of these 50 sites are shared in both the total number of species is to determine 77. The most representative families were Leguminoseae, Euphorbiaceae and Convulvolaceae. The structure of the burrows is not affected by the timing, but the content is determined with the amount of stored material but seed production is defined by the pattern of fruit that is given throughout the year.Key words: Burrows, structure, food hoarding, Liomys pictus, Jalisco, Mexico.

scholarly journals STRUCTURE AND FUNCTION OF THE FRUIT MICROBIOME IN HEALTHY AND DISEASED KIWIFRUIT

2019 ◽  
Vol 56 (03) ◽  
pp. 577-585
Author(s):  
Wenneng Wu
Keyword(s):  
Microbial Diversity ◽  
Relative Abundance ◽  
Foodborne Pathogens ◽  
Fungal Pathogens ◽  
Sugar Metabolism ◽  
Amino Sugar ◽  
Disease Diagnosis ◽  
Postharvest Disease ◽  
Pathogen Infection ◽  
Microbiome Composition

The fruit surface is an infection court where foodborne pathogens compete with indigenous microbiota for microsites to invade the fruits for nutrients acquisition. However, our current understanding of the structure and functions of fruit microbiome visa-vis postharvest pathogen infection is still nascent. Here, we sequenced the metagenomic DNA to understand the structural and functional attributes of healthy and diseased kiwifruit microbiome. The healthy fruits exhibited higher microbial diversity and distinct microbiome composition compared with diseased fruits. The microbiome of diseased fruit was dominated by fungal pathogens Neofusicoccum parvum and Diplodiaseriata, while the microbiome of healthy fruits were enriched by bacteria from Methylobacteriaceae, Sphingomonadaceae, Nocardioidaceae and fungi in Pleosporaceae. Importantly, the healthy fruit microbiome had a higher relative abundance of genes related to ABC transporter, two-component system, bacterial chemotaxis, bacterial secretion system, but had a lower relative abundance of genes associated with polycyclic aromatic hydrocarbon degradation, amino sugar and nucleotide sugar metabolism, glycine, serine and threonine metabolism compared with diseased fruits. Our results indicate that pathogen infection disrupts the fruit microbiome. The changes in microbiome composition and functions could also increase the possibility of secondary pathogen infection as the reduced microbial diversity may demonstrate less resistance to pathogens infection. Therefore, monitoring the microbiome dynamics and their functions using metagenomic approaches could be useful to build a predictive understanding of accurate postharvest disease diagnosis and management in the future

Genetic variation in the mitochondrial cytochrome c oxidase subunit 1 within Progamotaenia festiva (Cestoda: Anoplocephalidae) from macropodid marsupials

Parasitology ◽  
2007 ◽  
Vol 134 (10) ◽  
pp. 1465-1476 ◽  
Author(s):  
I. BEVERIDGE ◽  
S. SHAMSI ◽  
M. HU ◽  
N. B. CHILTON ◽  
R. B. GASSER
Keyword(s):  
Genetic Variation ◽  
Host Species ◽  
Sequence Data ◽  
Phylogenetic Analyses ◽  
Enzyme Electrophoresis ◽  
Single Strand Conformational Polymorphism ◽  
Oxidase Subunit ◽  
Single Host ◽  
Distinct Sequence ◽  
Sequence Types

SUMMARYGenetic variation was examined in the anoplocephalid cestode Progamotaenia festiva, from Australian marsupials, in order to test the hypothesis that P. festiva, is a complex of sibling species and to assess the extent of host switching reported previously based on multilocus enzyme electrophoresis (MEE). Polymerase chain reaction (PCR)-based single-strand conformational polymorphism (SSCP) was used for the analysis of sequence variation in the cytochrome c oxidase subunit 1 (cox1) gene among 179 specimens of P. festiva (identified based on morphology and predilection site in the host) from 13 different host species, followed by selective DNA sequencing. Fifty-three distinct sequence types (haplotypes) representing all specimens were defined. Phylogenetic analyses of these sequence data (utilizing maximum parsimony and neighbour-joining methods) revealed 12 distinct clades. Other heterologous species, P. ewersi and P. macropodis, were used as outgroups and the remaining bile-duct inhabiting species, P. diaphana and P. effigia, were included in the analysis for comparative purposes. The latter 2 species were nested within the clades representing P. festiva. Most clades of P. festiva identified were restricted to a single host species; one clade primarily in Macropus robustus was also found in the related host species M. antilopinus in an area of host sympatry; another clade occurring primarily in M. robustus occurred also in additional kangaroo species, M. rufus and M. dorsalis. High levels of genetic divergence, the existence of distinct clades and their occurrence in sympatry provide support for the hypothesis that P. festiva represents a complex of numerous species, most of which, but not all, are host specific. Three distinct clades of cestodes were found within a single host, M. robustus, but there was no evidence of within-host speciation.

THE NATURE AND DISTRIBUTION OF SALTS IN UNCULTIVATED SALINE SOILS IN SASKATCHEWAN

1964 ◽  
Vol 44 (2) ◽  
pp. 165-175 ◽  
Author(s):  
J. D. Dodd ◽  
R. T. Coupland ◽  
D. A. Rennie
Keyword(s):  
Plant Species ◽  
Relative Abundance ◽  
Analytical Data ◽  
Black Soil ◽  
Central Portion ◽  
Saline Soils ◽  
Magnesium Ions ◽  
Native Plant ◽  
Upland Soil ◽  
Native Plant Species

Investigations were undertaken to ascertain the relative abundance of various salts in uncultivated saline soils occurring in southern Saskatchewan. Sampling sites were selected within areas dominated by various native plant species and groups of species. One hundred and nineteen saline profiles in the Brown, Dark Brown, and Black soil zones were studied and classified into five subgroup profile types, which were usually associated in a catenary sequence. The Saline Gleyed Regosol occupied the central portion of depressional areas, followed successively by the Saline Gleysol, and the Saline Meadow, with the Saline Calcareous Chernozem occupying the perimeter of the depression and the Saline Rego Chernozem being transitional to upland soil. Nine species which commonly form extensive stands were associated in their distribution with these subgroup profile types. Analytical data from saturation extracts of samples taken from the 0–6, 6–12, 12–24, and 24–36 in. depths are discussed with reference to concentration and composition. With one exception, all samples showed a preponderance of sodium and magnesium ions. Soluble sodium percentages in extreme cases exceeded 90%. Sulphates, chlorides, and bicarbonates were present in practically all samples. While sulphate was the predominant anion, significant quantities of chlorides and bicarbonates were present in all profiles.

The occurrence of species flocks in the nematode genus Cloacina (Strongyloidea : Cloacininae), parasitic in the stomachs of kangaroos and wallabies

2002 ◽  
Vol 50 (6) ◽  
pp. 597 ◽  
Author(s):  
I. Beveridge ◽  
N. B. Chilton ◽  
D. M. Spratt
Keyword(s):  
Host Specificity ◽  
Host Species ◽  
Nematode Species ◽  
Morphological Data ◽  
Species Flock ◽  
Sampling Effort ◽  
Nematode Genus ◽  
Single Host ◽  
Species Flocks ◽  
Occurrence Of Species

The occurrence of species flocks within the nematode genus Cloacina was examined using the criteria of host specificity, co-occurrence and monophyly. Species of Cloacina generally exhibited a high degree of host specificity, with most species occurring either in a single host species or in two closely related host species. The frequency distribution of numbers of component species of Cloacina per host species indicated that most host species harboured 2–4 species of nematodes, with an approximately exponential decline in the number of species of parasites to a maximum of 20 species of nematode per host species. Host species harbouring eight or more species of Cloacina were found within a single recent macropodid clade, but there was no correlation between evolutionary age of the host and the number of parasite species harboured. Sampling effort was significantly correlated with the number of nematode species found and, in partial regression analysis, subsumed the effects of host body size and geographic range, which were found to be significant correlates with the number of nematode species present in preliminary analyses. Analysis of co-occurrences of nematode species indicated significant variation between host species, with some hosts (e.g. Macropus agilis) most commonly harbouring a single species of Cloacina, while closely related host species (e.g. M. dorsalis) most commonly harboured numerous species. Parsimony analysis of species of Cloacina based on morphological data suggested that while small series of related nematode species could be identified within a single host species, the species flock in each host species is polyphyletic in origin. Species flocks contributed significantly to community richness in some host species.

Eight New Species of Sucking Lice (Psocodea: Phthiraptera) From Endemic Murine Rodents in Australia and an Updated Identification Key

2020 ◽  
Author(s):  
Wei Wang ◽  
Lance A Durden ◽  
Haylee Weaver ◽  
Renfu Shao
Keyword(s):  
New Species ◽  
Host Species ◽  
Identification Key ◽  
Museum Specimens ◽  
Dichotomous Key ◽  
Sucking Lice ◽  
Single Host ◽  
Murine Rodents ◽  
Louse Species ◽  
Comprehensive Study

Abstract Based on a comprehensive study of museum specimens, eight new species of sucking lice of the genus Hoplopleura Enderlein, 1904 (Psocodea: Phthiraptera: Hoplopleuridae), are described from six genera of Australian Old Endemic rodents: Conilurus Ogilby, 1838 (Rodentia: Muridae), Leggadina Thomas, 1910 (Rodentia: Muridae), Leporillus Thomas, 1906 (Rodentia: Muridae), Mesembriomys Palmer, 1906 (Rodentia: Muridae), Pogonomys Milne-Edwards, 1877 (Rodentia: Muridae), and Xeromys Thomas, 1889 (Rodentia: Muridae). The description of these new species increases the number of sucking louse species from endemic Australian rodents from 13 to 21 and extends the records of sucking lice to all of the 14 genera of endemic rodents in Australia. Our results show that sucking lice are much more diverse among rodents in Australia than previously known. Furthermore, the Australian Hoplopleura species are host specific—each Hoplopleura species, including the eight new species described in the present study, parasitizes only a single host species, except Hoplopleura irritans Kuhn and Ludwig, 1967 (Psocodea: Phthiraptera: Hoplopleuridae) and Hoplopleura melomydis Weaver, 2017 (Psocodea: Phthiraptera: Hoplopleuridae), each of which is found on two host species. An updated dichotomous key for identifying Australian Hoplopleura species is included.

Host species of mistletoes (Loranthaceae and Viscaceae) in Australia

2020 ◽  
Vol 68 (1) ◽  
pp. 1
Author(s):  
Nicole F. Clark ◽  
Jen A. McComb ◽  
Andrew W. Taylor-Robinson
Keyword(s):  
Alien Species ◽  
Host Species ◽  
Current Knowledge ◽  
Sampling Effort ◽  
New Host ◽  
Host Family ◽  
Single Host ◽  
New Hosts ◽  
Host Families ◽  
New Host Species

In order to study the relationships between mistletoes and their host species, comprehensive collections of both mistletoes and hosts are needed. The effect of sampling effort on the estimation of mistletoe host range was demonstrated in a comparison of an inventory of host mistletoe interactions published by Downey in 1998 and a 2019 inventory presented here, which is based on data from collections in the Australian Virtual Herbarium and information in the literature. New hosts were recorded for 93% of the 90 Australian mistletoes. There were 338 previously known hosts recorded to be parasitised by additional mistletoe species, and 317 new host species that were not previously known as mistletoe hosts (25 being alien species). These were from 78 new host genera and 13 new host families. The total number of host species was 1186 within 327 genera from 92 host families. A total of 63% of all Australian mistletoes parasitise species of either Eucalyptus or Acacia or both these genera. The large rise in host species recorded in less than two decades between inventories suggests that current knowledge of hosts is still incomplete, such that further new hosts will be discovered in future. Some mistletoe species show a strong preference to one host family or genus but due to insufficient collecting it is premature to conclude that any of the three species known from a single host are host specific.

scholarly journals Fungal diversity regulates plant-soil feedbacks in temperate grassland

2018 ◽  
Vol 4 (11) ◽  
pp. eaau4578 ◽  
Author(s):  
Marina Semchenko ◽  
Jonathan W. Leff ◽  
Yudi M. Lozano ◽  
Sirgi Saar ◽  
John Davison ◽  
...  
Keyword(s):  
Soil Properties ◽  
Plant Species ◽  
Mycorrhizal Fungi ◽  
Vegetation Dynamics ◽  
Fungal Pathogens ◽  
Soil Microbial Communities ◽  
Temperate Grassland ◽  
Saprotrophic Fungi ◽  
Plant Resource ◽  
Plant Soil

Feedbacks between plants and soil microbial communities play an important role in vegetation dynamics, but the underlying mechanisms remain unresolved. Here, we show that the diversity of putative pathogenic, mycorrhizal, and saprotrophic fungi is a primary regulator of plant-soil feedbacks across a broad range of temperate grassland plant species. We show that plant species with resource-acquisitive traits, such as high shoot nitrogen concentrations and thin roots, attract diverse communities of putative fungal pathogens and specialist saprotrophs, and a lower diversity of mycorrhizal fungi, resulting in strong plant growth suppression on soil occupied by the same species. Moreover, soil properties modulate feedbacks with fertile soils, promoting antagonistic relationships between soil fungi and plants. This study advances our capacity to predict plant-soil feedbacks and vegetation dynamics by revealing fundamental links between soil properties, plant resource acquisition strategies, and the diversity of fungal guilds in soil.

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