scholarly journals Community context modifies response of host-parasitoid interactions to phenological mismatch under warming

2021 ◽  
Author(s):  
Nicholas Pardikes ◽  
Tomas Revilla ◽  
Chia-Hua Lue ◽  
Melanie Thierry ◽  
Daniel Souto-Villaros ◽  
...  
Keyword(s):  
Intraspecific Competition ◽  
Host Species ◽  
Species Interactions ◽  
Community Context ◽  
Ecological Communities ◽  
Alternative Host ◽  
Parasitism Rates ◽  
Future Global Warming ◽  
Phenological Shifts ◽  
Community Contexts

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 of availability. Using a combination of laboratory experiments and dynamic simulations, we quantified how the effects of phenological shifts in Drosophila-parasitoid interactions differed with concurrent changes in temperature, intraspecific competition, and the presence of alternative host species. We found that community context, particularly the presence of alternative host species, supported interaction persistence across a wider range of phenological shifts than pairwise interactions. Parasitism rates declined under warming, which limited the ability of community contexts to manage mismatched interactions. These results demonstrate that ongoing declines in insect diversity may exacerbate the effects of phenological shifts in ecological communities under future global warming temperatures.

Two sympatric root hemiparasitic Pedicularis species differ in host dependency and selectivity under phosphorus limitation

2012 ◽  
Vol 39 (9) ◽  
pp. 784 ◽  
Author(s):  
Ai-Rong Li ◽  
F. Andrew Smith ◽  
Sally E. Smith ◽  
Kai-Yun Guan
Keyword(s):  
Intraspecific Competition ◽  
Host Species ◽  
Species Interactions ◽  
Developmental Stages ◽  
Phosphorus Limitation ◽  
Wide Distribution ◽  
Interaction Patterns ◽  
Species Identity ◽  
Root Shoot Ratio ◽  
Host Parasite

Parasitic biology of Pedicularis L. (Orobanchaceae) has been underinvestigated despite its wide distribution and potential ecological significance. To better understand the parasitic aspects of the root hemiparasites, host–parasite interactions were investigated with two sympatric Pedicularis species, Pedicularis rex C. B. Clarke and Pedicularis tricolor Hand.-Mazz., at two developmental stages. Plant DW, shoot phosphorus (P) content, root : shoot ratio and number of haustoria were measured in Pedicularis grown with either a host plant or a plant of its own species in pot experiments. In addition, effects of parasitism and intraspecific competition on growth and biomass allocation in four host species belonging to three major functional groups (grasses, legumes and forbs) were investigated. The two Pedicularis species showed obvious host preference, but preferred different host species. Interactions between Pedicularis and their hosts depended on both species identity and developmental stages of the partners. Overall, P. rex showed much weaker host dependency and less damage to hosts than P. tricolor. Interspecific variations were observed among different host species in their responses to intraspecific competition and parasitism. We concluded that different Pedicularis-host pairs showed different interaction patterns. Sympatric Pedicularis may have differential influence on plant community structure and productivity.

scholarly journals Higher order interactions and species coexistence

2020 ◽  
Author(s):  
Pragya Singh ◽  
Gaurav Baruah
Keyword(s):  
Intraspecific Competition ◽  
Species Interactions ◽  
Species Coexistence ◽  
General Rule ◽  
Higher Order ◽  
Volterra Model ◽  
Ecological Communities ◽  
Wide Range ◽  
Analytical Result ◽  
Underlying Mechanisms

AbstractHigher order interactions (HOIs) have been suggested to stabilize diverse ecological communities. However, their role in maintaining species coexistence from the perspective of modern coexistence theory is not known. Here, using generalized Lotka-Volterra model, we derive a general rule for species coexistence modulated by HOIs. We show that where pairwise species interactions fail to promote species coexistence in regions of extreme fitness differences, negative HOIs that intensify pairwise competition, however, can promote coexistence provided that HOIs strengthen intraspecific competition more than interspecific competition. In contrast, positive HOIs that alleviate pairwise competition can stabilize coexistence across a wide range of fitness differences, irrespective of differences in strength of inter- and intraspecific competition. In addition, we extend our three-species analytical result to multispecies communities and show, using simulations, that multispecies coexistence is possible provided that strength of negative intraspecific HOIs is higher than interspecific HOIs. Our work sheds light on the underlying mechanisms through which HOIs can maintain species diversity.

scholarly journals Multiple parasitoid species enhance top-down control, but parasitoid performance is context-dependent

2021 ◽  
Author(s):  
Melanie Thierry ◽  
Nicholas A. Pardikes ◽  
Miguel G Ximenez-Embrun ◽  
Gregoire Proudhom ◽  
Jan Hrcek
Keyword(s):  
Community Structure ◽  
Host Species ◽  
Species Interactions ◽  
Switching Behavior ◽  
Global Changes ◽  
Ecological Communities ◽  
Parasitoid Species ◽  
Species Identity ◽  
Larval Parasitoid ◽  
Species Specific

Ecological communities are composed of a multitude of interacting species, forming complex networks of interactions. Current global changes are altering community composition and we thus need to understand if the mechanisms structuring species interactions are consistent across different species compositions. However, it is challenging to explore which aspects of species interactions are primarily driven by community structure and which by species identity. Here we compared the outcome of host-parasitoid interactions across four community modules that are common in host-parasitoid communities with a laboratory experiment using a pool of three Drosophila host and three larval parasitoid species, resulting in nine different species assemblages. Our results show general patterns of community structure for host-parasitoid interactions. Multiple parasitoid species enhanced host suppression without general antagonistic effects between parasitoid species. Presence of an alternative host species had no general effects on host suppression nor on parasitoid performance, therefore showing no evidence of indirect interactions between host species nor any host switching behavior. However, effects of community structure on parasitoid performance were species-specific and dependent on the identity of co-occurring species. Consequently, our findings highlight the importance of both the structure of the community and its species composition for the outcome of interactions.

scholarly journals Altered parasitism of a butterfly assemblage associated with a range-expanding species

2020 ◽  
Author(s):  
H. Audusseau ◽  
N. Ryrholm ◽  
C. Stefanescu ◽  
S. Tharel ◽  
C. Jansson ◽  
...  
Keyword(s):  
Host Species ◽  
Land Use Changes ◽  
Biotic Interactions ◽  
Host Community ◽  
Butterfly Species ◽  
Ecological Communities ◽  
Species Assemblage ◽  
Resident Species ◽  
Parasitism Rates ◽  
The Impact

AbstractAimBiotic interactions are an important factor structuring ecological communities but data scarcity limits our understanding of the impact of their response to climate and land use changes on communities. We studied the impact of a change in species assemblage on biotic interactions in a community of closely-related butterflies. Specifically, we examined the impact of the recent range expansion of Araschnia levana on the resident species, with a particular focus on natural enemies, parasitoids, shared with other butterfly species in the assemblage.LocationSweden.Time periodTwo years (2017-2018).Major taxa studiedNettle-feeding butterflies (Aglais urticae, Aglais io, Araschnia levana, and Vanessa atalanta) and their parasitoids.MethodsWe assessed parasitism in 6777 butterfly larvae sampled in the field from 19 sites distributed along a 500 km latitudinal gradient, and every two weeks throughout species’ reproductive seasons. We identified the parasitoid complex of each butterfly species and their overlap, and analysed how parasitism rates were affected by species assemblage, variations in abundance, time, and the arrival of A. levana.ResultsParasitoids caused high mortality, with substantial overlap across the four host species. The composition of the host community influenced parasitism rates and this effect was specific to each species. In particular, the rate of parasitism in resident species was comparatively higher at sites where A. levana has been established for longer.Main conclusionsParasitoid pressure is a significant source of mortality in the nettle-feeding butterfly community studied. Variations in butterfly species assemblages are associated with substantial variations in rates of parasitism. This is likely to affect the population dynamics of their butterfly host species, and, potentially, the larger number of species with which they interact.

scholarly journals Host density predicts the probability of parasitism by avian brood parasites

2019 ◽  
Vol 374 (1769) ◽  
pp. 20180204 ◽  
Author(s):  
Iliana Medina ◽  
Naomi E. Langmore
Keyword(s):  
Spatial Distribution ◽  
Reproductive Success ◽  
Host Species ◽  
Field Data ◽  
Host Density ◽  
Brood Parasites ◽  
Parasitism Rates ◽  
Analyse Data ◽  
First Time ◽  
Determining Factor

The spatial distribution of hosts can be a determining factor in the reproductive success of parasites. Highly aggregated hosts may offer more opportunities for reproduction but can have better defences than isolated hosts. Here we connect macro- and micro-evolutionary processes to understand the link between host density and parasitism, using avian brood parasites as a model system. We analyse data across more than 200 host species using phylogenetic comparative analyses and quantify parasitism rate and host reproductive success in relation to spatial distribution using field data collected on one host species over 6 years. Our comparative analysis reveals that hosts occurring at intermediate densities are more likely to be parasitized than colonial or widely dispersed hosts. Correspondingly, our intraspecific field data show that individuals living at moderate densities experience higher parasitism rates than individuals at either low or high densities. Moreover, we show for the first time that the effect of host density on host reproductive success varies according to the intensity of parasitism; hosts have greater reproductive success when living at high densities if parasitism rates are high, but fare better at low densities when parasitism rates are low. We provide the first evidence of the trade-off between host density and parasitism at both macro- and micro-evolutionary scales in brood parasites. This article is part of the theme issue ‘The coevolutionary biology of brood parasitism: from mechanism to pattern’.

scholarly journals Consumer sexual dimorphism promotes coexistence among competing resources

2019 ◽  
Author(s):  
Stephen P. De Lisle ◽  
Gonzalo Hernando ◽  
Daniel I. Bolnick
Keyword(s):  
Sexual Dimorphism ◽  
Species Interactions ◽  
Natural Populations ◽  
Salient Feature ◽  
Apparent Competition ◽  
Species Variation ◽  
Ecological Communities ◽  
Key Factor ◽  
Classical Models ◽  
Resource Dynamics

AbstractWithin-species variation is a salient feature of natural populations, of substantial importance for species interactions. However, the community consequences of sexual dimorphism, one of the most ubiquitous sources of within-species variance, remains poorly understood. Here, we extend classical models of consumer-resource dynamics to explore the ecological consequences of consumer sexual dimorphism. We show that sexual dimorphism in consumer attack rates on two different resource species promotes coexistence between those resources, mitigating the effects of both apparent competition and direct interspecific competition. Consumer sexual dimorphism can prevent exclusion of a resource with inferior growth rates because reduction in any of the two resources reduces consumer density, generating negative frequency dependence that stabilizes coexistence between resources. Our work highlights ecological sex differences as a potentially key factor governing the assembly of ecological communities, illustrating that the specific source of within-species variance can have important implications for community ecology.

Diversity, distribution and parasitism rates of fleas (Insecta: Siphonaptera) on sigmodontine rodents (Cricetidae) from Argentinian Patagonia

2018 ◽  
Vol 109 (1) ◽  
pp. 72-83 ◽  
Author(s):  
J. Sanchez ◽  
M. Lareschi
Keyword(s):  
Host Species ◽  
Arid Regions ◽  
Epidemiological Studies ◽  
Surveillance Systems ◽  
Parasitism Rate ◽  
Host Environment ◽  
Ecological Aspects ◽  
Parasitism Rates ◽  
Survival And Development ◽  
Causative Agents

AbstractFleas have great medical relevance as vectors of the causative agents of several diseases in animals and humans and rodents are the principal reservoirs for these pathogens. Argentinian Patagonia has the highest diversity of rodent fleas in South America. However, parasitism rates of rodents by fleas, the factors that influence them and the ecological aspects that modulate geographical distributions of flea–host association remain unknown for this region. This is the first study to record the diversity, prevalence, abundance, geographical distributions and host ranges of fleas in Argentinian Patagonia. It also compares parasitism rates among Patagonian ecoregions and host species. We captured 438 rodents belonging to 13 species, which harboured 624 fleas from 11 species and subspecies (P = 46%; mean abundance = 1.44). The high parasitism rates obtained were consistent with previous records for other arid regions, suggesting that Patagonia favours the survival and development of Siphonaptera. Host geographic range and abundance were related to the parasitological indexes: host species with high-density populations had the highest mean flea abundance and prevalence, whereas widely distributed hosts had the highest richness and diversity of flea species. Our results contribute to the knowledge of the flea–host–environment complex. Our analysis of flea distributions and parasitism rate in Central Patagonia may be useful in epidemiological studies of flea-borne diseases and provide a basis for implementing surveillance systems for better risk assessment of emerging zoonoses in the region.

Composition patterns and network structure of epiphyte–host interactions in Chilean and New Zealand temperate forests

2021 ◽  
Author(s):  
A Taylor ◽  
A Saldaña ◽  
G Zotz ◽  
C Kirby ◽  
I Díaz ◽  
...  
Keyword(s):  
New Zealand ◽  
Host Species ◽  
Species Interactions ◽  
Temperate Forests ◽  
Null Model ◽  
Host Interactions ◽  
Host Trees ◽  
Specific Host ◽  
Random Patterns ◽  
Epiphyte Species

Ecological networks are becoming increasingly used as a framework to study epiphyte–host interactions. However, efforts to quantify the properties of epiphyte–host networks have produced inconsistent results. Epiphyte–host interactions in New Zealand and Chilean temperate forests were quantified to test for non-random patterns in nestedness, negative co-occurrences, number of links, and network specialisation. Results showed that three out of five New Zealand networks were significantly more nested than null model expectations, compared with just one out of four Chilean networks. Epiphytes co-occurred more often than null model expectations in one New Zealand network and one in Chile. In all cases, the number of links maintained by each epiphyte and host species was consistent with null model expectations. Lastly, two New Zealand networks and one in southern Chile were significantly less specialised than null model expectations, with all remaining networks returning low specialisation scores. As such, aside from the tendency for greater nestedness in New Zealand networks, most epiphyte species were distributed on their host trees at random. We attribute the result of nestedness in New Zealand to the abundance of large nest epiphytes (Astelia spp. in particular), which may facilitate the sequential colonisation of epiphyte species on developing host trees. The lack of negative co-occurrences suggests that negative species interactions are not an important determinant of species assemblage structure. Low network specialisation scores suggest that epiphytes are selecting for specific host traits, rather than specific host species for colonisation.

scholarly journals How does timing of flowering affect competition for pollinators, flower visitation and seed set in an early spring grassland plant?

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Sandra Kehrberger ◽  
Andrea Holzschuh
Keyword(s):  
Species Interactions ◽  
Seed Set ◽  
Weather Conditions ◽  
Early Spring ◽  
Flowering Plants ◽  
Early Flowering ◽  
Flower Visitation ◽  
Floral Longevity ◽  
Visitation Rates ◽  
Phenological Shifts

Abstract Knowledge on how the timing of flowering is related to plant fitness and species interactions is crucial to understand consequences of phenological shifts as they occur under climate change. Early flowering plants may face advantages of low competition for pollinators and disadvantages of low pollinator abundances and unfavourable weather conditions. However, it is unknown how this trade-off changes over the season and how the timing affects reproductive success. On eight grasslands we recorded intra-seasonal changes in pollinators, co-flowering plants, weather conditions, flower visitation rates, floral longevity and seed set of Pulsatilla vulgaris. Although bee abundances and the number of pollinator-suitable hours were low at the beginning of the season, early flowers of P. vulgaris received higher flower visitation rates and estimated total number of bee visits than later flowers, which was positively related to seed set. Flower visitation rates decreased over time and with increasing number of co-flowering plants, which competed with P. vulgaris for pollinators. Low interspecific competition for pollinators seems to be a major driver for early flowering dates. Thus, non-synchronous temporal shifts of co-flowering plants as they may occur under climate warming can be expected to strongly affect plant-pollinator interactions and the fitness of the involved plants.

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