Interspecific Interference Research Articles

Analysis of an intra- and interspecific interference model with allelopathic competition

In this paper, we propose an original model of two-microbial species competing for a single nutrient in the chemostat including general intra- and interspecific density-dependent growth rates with allelopathic interactions. Each species produces a toxin that affects the growth of other species as well as its own growth. The removal rates are distinct and include the specific death rate and the autotoxicity of each species. We establish an in-depth mathematical analysis by determining the multiplicity of all steady states of the three-dimensional system and their necessary and sufficient conditions of existence and local stability according to the operating parameters, which are the dilution rate and the inflowing concentration of the substrate. To describe the asymptotic behavior of the process according to these control parameters, we first determine theoretically the operating diagram. Using MATCONT software, these theoretical results are validated numerically but it reveals the cusp bifurcation that occurs by varying two parameters. The one-parameter bifurcation diagram in the dilution rate shows that there can be either transcritical or saddle-node bifurcations. Finally, we apply our results to a particular model in the literature without intra- and interspecific interference but with only allelopathic effects of the second species on the first species. We show that one of the coexistence steady states is locally exponentially stable when it exists, whereas in the literature they have not been able to demonstrate that the stability condition of this steady state is always fulfilled.

Intraguild species presence alters Aphidoletes aphidimyza (Diptera: Cecidomyiidae) and Aphidius gifuensis (Hymenoptera: Braconidae) foraging responses.

The predatory gall midge, Aphidoletes aphidimyza (Rondani), and tobacco aphid cocoon wasp, Aphidius gifuensis Ashmead, are important natural enemies of Myzus persicae (Sulzer) (Hemiptera: Aphididae). Predation by A. aphidimyza and A. gifuensis can regulate M. persicae; however, how interspecific interference competition affects their foraging efficiency is unknown. Here, we investigated the consumption and parasitization abilities of A. aphidimyza 3rd instar larva and A. gifuensis adults under various conditions. Consumption of parasitized aphids by A. aphidimyza 3rd instar larvae was significantly lower than that of nonparasitized controls, with a substantial increase in handling time. The presence of A. gifuensis adults did not significantly affect the predation capacity of A. aphidimyza larvae. Relative to controls, A. aphidimyza larvae predation trace (PT) and imago activity significantly decreased A. gifuensis parasitism rates at different aphid densities. Further, A. aphidimyza larvae PT increased the A. gifuensis handling time of M. persicae, whereas the presence of A. aphidimyza adults had the opposite effect. Coexistence with heterospecific natural enemies reduced the parasitic capacity of A. gifuensis, whereas A. aphidimyza larvae predation capability was influenced to a lesser extent. Our results demonstrate that intraguild interactions strongly influence the predatory and parasitic efficacy of A. aphidimyza and A. gifuensis, although the effect on A. gifuensis was more pronounced. For effective biological control of M. persicae using A. aphidimyza and A. gifuensis, we recommend releasing A. aphidimyza first to mitigate intraguild predation and enhance the overall success of the pest control program.

Coexistence of two species with intra- and interspecific competition in an unstirred chemostat

In this paper, we study an intra- and interspecific competition system with the different diffusion rates in an unstirred chemostat. Due to the present of the different diffusion rates, the conservation principle for a classical standard chemostat model does not hold here. Firstly, we prove the existence, the uniqueness and asymptotic behaviors of positive solution of the single population system by using the degree theory. Secondly, by the degree theory and standard bifurcation theory, the existence and global structure of the coexistence solutions are investigated. The results show that when the maximum growth rates of two microorganisms with different diffusion abilities are not small, two competing microorganisms will coexist. Finally, numerical simulations are performed to illustrate that the interspecific interference can help the weaker competitor to win in the competition.

Intra- and interspecific interactions in the two coexisting Locustella warblers revealed by song playback experiments

Males usually come into conflict due to competition for territories and females. However, interference competition can also occur between males of congeneric species when their ecological requirements are overlapping. Using acoustic playback experiments, we investigated male-male interactions within and between Grasshopper (Locustella naevia; GW) and River Warbler (L. fluviatilis; RW). Our objective was to evaluate the song and behavioural response of tested males of both species to conspecific song stimuli in order to compare this with the response to congeneric stimulus, based on which we could assess whether these two commonly co-existing species show interspecific territorialism. A total of nine GW and 11 RW males were tested in May and June 2019 in western Slovakia. The ability to differentiate between the heterospecific (control), congeneric, and conspecific stimuli was similar between the two species. Conspecific playback elicited the strongest non-vocal response and a significant change in vocalization. The GW males shortened the songs, while the RW males shortened the songs and also increased their syllable rate. The congeneric playback elicited a lower intensity of behavioural response than conspecific playback and no change in vocalization in either species. We conclude that interspecific interference competition between GW and RW is rather low, suggesting that the species' ecological requirements are separated, although these two congeneric species commonly share habitat.

Dynamics of a competition model with intra- and interspecific interference in the unstirred chemostat

This paper deals with an unstirred chemostat system with intra- and interspecific interference. We first investigate the uniqueness and asymptotic behaviors of the positive steady state solution of the single species model. The results show that the species cannot survive when the intraspecific interference is large enough. For two species system, we find that the two species can coexist when the influence of interspecific interference is relatively small, and that the system has no positive steady-state solution when the strength of interspecific interference is large enough. Furthermore, we study the influence of diffusion rate on species coexistence. The results show that for large diffusion rate, both species will be washed out, and the competition exclusion occurs at small diffusion rate. This indicates that species coexistence only occurs at intermediate diffusion rate.

Competition is a major limiting factor of refueling in migratory passerines during stopover

For an avian migrant, refueling capacity attainable during stopovers governs the entire migration schedule and, ultimately, its fitness. Specifically, timely replenishing energy stores is critical when migration involves crossing ecological barriers, within which refueling may be limited. Here, we tested the hypothesis that fuel deposition rates (FDRs) of migratory passerines within barrier‐edge stopover sites are constrained by the density of potential competitors, irrespective of migration season, phenology, and local environmental conditions. We also evaluated diverse intra‐ and inter‐specific competition scenarios and explored a potential mediation of density‐dependence by environmental factors. The analyzed data, collected by us over 13 consecutive years (2009–2022), contain information on seven species of long‐distance migratory insectivorous passerines measured within eight desert‐edge habitats throughout autumn and spring migrations. As predicted, our analyses revealed negative density‐dependence regulation of FDRs, consistent across species and migration seasons. Notably, bird density exerted its effect above and beyond the other factors known to influence FDR, such as relative ambient temperature, phenology, temporal progress of stopover, and body mass next to landfall. As expected, FDR increased at higher relative ambient temperatures and with the stopover's progress. In spring, FDR also rose as the season advanced. These findings signify the substantial impact of competition on the refueling performance of migratory passerines during their stopover on an ecological barrier's edge, acting over and above the other environmental factors. The detected importance of competition and its interrelation with other predictors provides an insight into stopover's functioning; environmentally imposed and inescapable interspecific interference is thus a significant limiting factor of FDR, a deleterious relationship potentially remediable by informed habitat restoration and planning.

Relative influence of inter- and intraspecific competition in an ungulate assemblage modified by introduced species.

Interspecific competition from introduced and naturally colonizing species has potential to affect resident populations, but demographic consequences for vertebrates have rarely been tested. We tested hypotheses of interspecific and intraspecific competition for density, body mass, and fertility of adult female Roe Deer (Capreolus capreolus) across a heterogeneous forest landscape occupied by two introduced deer species: Mediterranean Fallow Deer (Dama dama); and subtropical Reeve's Muntjac (Muntiacus reevesi). Species-specific deer densities in buffers around culling locations of 492 adult female Roe Deer, sampled over seven years, were extracted from spatially explicit models calibrated through annual nocturnal distance sampling. Roe Deer fertility and body mass were related to species-specific deer densities and extent of arable lands using piecewise structural equation models. Reeve's Muntjac density was lower at higher Fallow Deer densities, suggesting interspecific avoidance via interference competition, but greater when buffers included more arable land. Roe Deer body mass was marginally greater when buffers included more arable land and was independent of deer densities. However, Roe Deer fertility was unrelated to female body mass, suggesting that fertility benefits exceeded an asymptotic threshold of body condition in this low-density population. However, Roe Deer fertility was slightly greater rather than reduced in areas with greater local Roe Deer density, suggesting negligible intraspecific competition. In contrast, Roe Deer was less fertile in areas with greater Reeve's Muntjac densities; thus, interspecific exceeded intraspecific competition in this assemblage. In contrast, we found no support for any effects of Fallow Deer density on Roe Deer density, body mass, or fertility. Complex networks of interspecific competition operating in this deer assemblage include: interspecific interference from Fallow Deer exceeded habitat effects for Reeve's Muntjac; and interspecific competition from introduced, smaller sedentary Reeve's Muntjac reduced fertility, unlike intraspecific, or potential competition with larger, more mobile, Fallow Deer for native Roe Deer. Mechanisms driving Roe Deer fertility may include interspecific behavioral interference or stress-resource depletion is considered less likely because Roe Deer fertility was independent of body mass. Findings emphasize the importance of ensuring appropriate management strategies for controlling invasive species.

Interspecific interference in reproduction of Spectacled Guillemots Cepphus carbo by neighboring seabirds

Interspecific interference in reproduction of Spectacled Guillemots <i>Cepphus carbo</i> by neighboring seabirds

Interference competition following a recent invasion of plague skinks (Lampropholis delicata) into a nationally critical native skink population

Context Invasive species can threaten native species through exploitative and interference competition if they occupy similar ecological niches. The invasive plague skink (Lampropholis delicata) has been accidently introduced to New Zealand, Lord Howe Island, and the Hawaiian Islands. Resource usage overlaps between plague skinks and several New Zealand skinks, suggesting the potential for exploitative and interference competition. However, no competitive mechanism or population impact has been identified. In 2014–15, plague skinks colonised Bream Head Scenic Reserve, Northland, New Zealand, where they overlap in occupancy and habitat with the ‘Nationally Critical’ kakerakau skink (Oligosoma kakerakau). Aims We investigated intra- and interspecific interference competition between kakerakau and plague skinks in the wild. Methods We recorded naturally occurring encounters and quantified aggression at a short-lived resource (sun-basking sites). Key results Behavioural interactions were observed in 72% of all encounters with similar proportions of encounters resulting in agonistic interactions between intraspecific kakerakau skink encounters and interspecific kakerakau-plague encounters. Although kakerakau skinks and plague skinks reacted equally aggressively in an interspecific interaction, kakerakau skinks behaved significantly more aggressively in an interaction with a plague skink than with a conspecific. Juvenile kakerakau skinks were more likely than adults to exhibit submissive behaviours such as fleeing during interspecific interactions. Conclusions This is the first evidence of interference competition occurring between plague skinks and a native skink. Our study suggests that kakerakau skinks, particularly juveniles, may experience competitive exclusion at important resources. Implications Our findings indicate that plague skinks may pose a threat to native skink populations when habitat use overlaps.

Comparative reproductive biology of two sympatric Hypostomus in a Neotropical river

Congeneric species often coexist in sympatry using behavioral and morphological adaptations to reduce competition and interspecific interference, but reproductive patterns behind coexistence remain unknown. We analyzed the gonadal morphology and development, reproductive cycle, and population structure of two sympatric congeneric fishes to evaluate the degree of overlap and differentiation of the reproductive biology between species in a Neotropical river. Development of testes and ovaries were similar between species, both showing asynchronous gonadal development, large diameter of gametes and synthesis of mucosubstances by follicle cells to form adhesive eggs. Although the morphometry of germ cells did not present differences, the zona radiata of mature eggs in Hypostomus garmani was markedly thicker than H. francisci, which suggests different spawning habitats. Both species have greater reproductive activity in the rainy season, concomitant with increase in water temperature, however H. garmani initiates and ends its reproduction earlier than H. francisci, indicating a differentiation of reproductive periods. Sexually mature males and females of H. francisci reproduced at a larger mean size then H. garmani. The two congeneric species had a similar abundance and sex ratios in the study area. Results show that although the species exhibited broad overlap of reproductive traits, a spatial and temporal differentiation of the reproductive biology was present. This study contributes to understanding reproductive mechanisms that may facilitate coexistence between congeneric sympatric species.

Do distylous syntopic plant species partition their floral morphological traits?

AbstractMorphological niche partitioning between related syntopic plants that are distylous (with short- and long-styled morphs) is complex. Owing to differences in the heights of stigmas and anthers, each floral morph must place pollen onto two distinct parts of the body of the pollinator. This led us to hypothesize that such partitioning should be more accurate among distylous syntopic species in comparison to combinations with other related plants that do not co-occur. We tested these assumptions using a set of Palicourea (Rubiaceae) species as a model system. We compared the distribution, flowering phenology, floral measurements and reciprocity of sexual organ heights of two syntopic species (Palicourea rigida and Palicourea coriacea) and one non-syntopic congener (Palicourea marcgravii). The three species overlapped in their distributions and flowering periods. The position of sexual organs was, in most cases, partitioned between syntopic populations, with low overlap in anther and stigma heights. However, we found a higher overlap involving the non-syntopic species, especially between Palicourea rigida and Palicourea marcgravii. Additionally, reciprocity of sexual organs was more accurate in intraspecific inter-morph combinations (i.e. legitimate organ correspondence) in comparison to intraspecific intra-morph, interspecific syntopic and interspecific non-syntopic combinations. The partitioning of morphological traits between syntopic species might facilitate the differential placement of pollen on the body of the pollinator and reduce the chances of interspecific interference.

Rising temperatures affect the interspecific interference competition between Harmonia axyridis and Propylea japonica, and their predation rate on Myzus persicae

Rising temperatures affect the interspecific interference competition between Harmonia axyridis and Propylea japonica, and their predation rate on Myzus persicae

An Extension of Two Species Lotka-Volterra Competition Model

Limiting resource is a angular stone of the interactions between species in ecosystems such as competition, prey-predators and food chain systems. In this paper, we propose a planar system as an extension of Lotka-Volterra competition model. This describes two competitive species for a single resource which are affected by intra and inter-specific interference. We give its complete analysis for the existence and local stability of all equlibria and some conditions of global stability. The model exhibits a rich set of behaviors with a multiplicity of coexistence equilibria, bi-stability, tri-stability and occurrence of global stability of the exclusion of one species and the coexistence equilibrium. The asymptotic behavior and the number of coexistence equilibria are shown by a saddle-node bifurcation of the level of resource under conditions on competitive effects relatively to associated growth rate per unit of resource. Moreover, we determine the competition outcome in the situations of Balanced and Unbalanced intra-inter species competition effects. Finally, we illustrate results by numerical simulations.

High-performance triplex PCR detection of three tapeworm species belonging to the genus Raillietina in infected poultry

Chickens and ducks are important sources of essential proteins and nutrition for global consumption, especially their eggs and meat. Tapeworm infections in chickens and ducks are the cause of serious poultry health and economic problems in the processing of livestock and food production systems. Raillietina are cosmopolitan in distribution and are possibly the most common tapeworm parasites. There are three important species regarding avian infection, with different pathogenicity, including Raillietina echinobothrida, R. tetragona, and R. cesticillus. Co-infection diagnosis of these tapeworms using morphological analysis can be performed, but this is time-consuming and complicated. Therefore, this study aimed to develop a triplex PCR for the detection and discrimination of three Raillietina species. The triplex PCR assay specifically amplified target DNAs with no inter-specific interference and produced a specific band for each species. According to the specificity test, there was no cross-amplification with the DNA template of related parasites and their hosts. The lowest detectable DNA concentrations were evaluated and provided sensitivities of 0.5 pg/μL for R. echinobothrida, 5 pg/μL for R. tetragona, 50 fg/μL for R. cesticillus, and 5 pg/μL for the combination of DNA from all three species. Simultaneous detection limits of egg capsules and gravid proglottids was also performed, with and without feces. The interference of feces in the reaction was related to a decrease in sensitivity, but simultaneous detection of three Raillietina species in amounts lower than one gravid proglottid and ten egg capsules was still successful. Thus, this study is the first triplex PCR assay for Raillietina detection and can be utilized as an alternative diagnostic tool for the detection and discrimination of R. echinobothrida, R. tetragona, and R. cesticillus infection in poultry through the verification of fecal specimens. In addition, it could improve the performance of specific treatments and promote veterinary healthcare.

Predator interference and complexity\u2013stability in food webs

It is predicted that ecological communities will become unstable with increasing species numbers and subsequent interspecific interactions; however, this is contrary to how natural ecosystems with diverse species respond to changes in species numbers. This contradiction has steered ecologists toward exploring what underlying processes allow complex communities to stabilize even through varying pressures. In this study, a food web model is used to show an overlooked role of interference among multiple predator species in solving this complexity–stability problem. Predator interference in large communities weakens species interactions due to a reduction in consumption rates by prey-sharing species in the presence of predators in response to territorial and aggressive behavior, thereby playing a key stabilizing role in communities. Especially when interspecific interference is strong and a community has diverse species and dense species interactions, stabilization is likely to work and creates a positive complexity–stability relationship within a community. The clear positive effect of complexity on community stability is not reflected by/intraspecific interference, emphasizing the key role of interspecific interference among multiple predator species in maintaining larger systems.

Mechanisms of reduced interspecific interference between territorial species

AbstractInterspecific territoriality has complex ecological and evolutionary consequences. Species that interact aggressively often exhibit spatial or temporal shifts in activity that reduce the frequency of costly encounters. We analyzed data collected over a 13-year period on 50 populations of rubyspot damselflies (Hetaerina spp.) to examine how rates of interspecific fighting covary with fine-scale habitat partitioning and to test for agonistic character displacement in microhabitat preferences. In most sympatric species, interspecific fights occur less frequently than expected based on the species’ relative densities. Incorporating measurements of spatial segregation and species discrimination into the calculation of expected frequencies accounted for most of the reduction in interspecific fighting (subtle differences in microhabitat preferences could account for the rest). In 23 of 25 sympatric population pairs, we found multivariate differences between species in territory microhabitat (perch height, stream width, current speed, and canopy cover). As predicted by the agonistic character displacement hypothesis, sympatric species that respond more aggressively to each other in direct encounters differ more in microhabitat use and have higher levels of spatial segregation. Previous work established that species with the lowest levels of interspecific fighting have diverged in territory signals and competitor recognition through agonistic character displacement. In the other species pairs, interspecific aggression appears to be maintained as an adaptive response to reproductive interference, but interspecific fighting is still costly. We now have robust evidence that evolved shifts in microhabitat preferences also reduce the frequency of interspecific fighting.

Salinity gradients and interspecific competition determine the distribution of chthamalid barnacles in a subtropical estuary

Distribution patterns in the upper intertidal zone, where diversity is low, are often explained by the variation in physical factors. However, certain environmental conditions may hinder resource monopolization by a dominant species, allowing for the coexistence of species. Under these conditions, interspecific interactions may become relevant. In southeastern Brazil, the upper intertidal zone of exposed rocky shores is typically colonized by the barnacle Chthamalus bisinuatus. In estuaries, two other species, Chthamalus proteus and Microeuraphia rhizophorae, may occur on hard substrates, although patterns of coexistence at relevant spatial scales are presently unknown, which prevents a better understanding of the ecology of rocky shore systems in the region. This study aimed to (i) describe the distribution patterns of chthamalid barnacles along the Paranaguá Estuarine Complex (PEC) and (ii) evaluate the vertical distribution of species in places where substantial coexistence was observed to preliminarily test whether their distribution is compatible with a lottery model of resource acquisition or compatible with a process of interspecific interference competition. A well-defined barnacle community was observed along the upper intertidal zone, from the euhaline to the oligohaline sector, with the cover area being larger in the euhaline sector. The effects of hydrodynamic exposure were limited to the euhaline sector, where barnacles covered larger extensions of the rocky intertidal habitat at more exposed sites. Barnacle density did not vary consistently among sectors or levels of hydrodynamic exposure but changed according to certain combinations of these factors. As a result, the realized habitat tended to decrease from the mouth of the estuary to the oligohaline sector. Three species were recorded in this study: Chthamalus bisinuatus, practically limited to the euhaline sector; Microeuraphia rhizophorae, limited to the polyhaline and mesohaline sectors; and Chthamalus proteus, limited to the polyhaline, mesohaline and oligohaline sectors. Habitat sharing was substantial only in 3 of the 16 sampled sites and only between Microeuraphia rhizophorae and Chthamalus proteus. At low barnacle densities, up to 40% substrate cover, there was no apparent vertical segregation between these two species. Above 40–50% cover, Microeuraphia rhizophorae occupied a higher position on the shore than Chthamalus proteus. These results suggest a lottery model when vacant space is still abundant and interspecific interference competition when barnacle abundance surpasses a critical abundance threshold. In this latter case, Chthamalus proteus displaces Microeuraphia rhizophorae to upper zone levels, where conditions for growth and reproduction are probably less favorable.

Influence of Interspecific Interference Competition on the Genetic Structure of Calopteryx splendens Populations

Understanding the effects of interspecific competition on genetic diversity will deepen our knowledge on species evolution. In the case of Calopteryx splendens and C. virgo, sympatric damselfly species, interspecific interference competition by C. virgo has remarkable effects on territoriality of C. splendens resulting in reproductive character displacement. Since territoriality is correlated with phenotype and mating success, we investigated the effects of interspecific interference competition on genetic diversity of C. splendens populations. Using amplified fragment length polymorphisms (AFLP), we determined the population genetic structure of 12 C. splendens populations and used the genetic diversity information to relate heterozygosity of C. splendens to abundance of C. virgo in sympatric populations. We found that heterozygosity of C. splendens males decreased with increasing abundance of C. virgo males. This result most likely reflects changes in effective population size due to interspecific interference competition and shows an effect on genetic structure in damselfly populations.

Trait-Based Models of Decomposition with Interspecific and Environmental Interactions

Most saprotrophic fungi are dominant decomposers, and they play a vital role in the carbon cycle and stability of ecosystem. Previous researchers examined that how traits and environments influence the decomposition rate(DR), but few studies last long enough to scale short-term results up to long-term trends. In this paper, we build several trait-based models of decomposition with interspecific and environmental interactions to describe both short- and long-term trends. First, we build the model of decomposition ratio versus time with covariates – hyphal extension ratio and moisture tolerance for each species. Second, we define Interspecific Interference Ratio (IIR) to reflect interactions between fungi species and rank the relative competitiveness based on Grey System Theory with four evaluation indices: hyphal extension rate, moisture niche width, the hyphal density and thermal niche width. Then, we predict the relative advantages and disadvantages for different species by IIR and analyze the impact of biodiversity. Finally, we perform sensitivity and robustness analysis of our models, which exhibits the wide prospects and a deeper understanding of the role of fungi in the ecosystem.

Kochia (Kochia scoparia) and Wild Oat (Avena fatua) Intraspecific and Interspecific Interference

Kochia (Kochia scoparia) and wild oat (Avena fatua) are highly problematic western Canadian weeds. Wild oat is widely distributed and has been a long-standing agricultural pest across Manitoba, Saskatchewan, and Alberta. Kochia populations are patchy and occur more frequently within the southern regions of the Prairie provinces. Kochia is exhibiting an ever-evolving, aggressive, herbicide resistance survival strategy which may facilitate range expansion. The experimental objective was to study the interspecific and intraspecific interference between wild oat and kochia. The study was developed with the context of kochia tumbleweeds travelling and depositing seed within wild oat infestations. Greenhouse experiments were conducted in Saskatoon, SK. The experimental design was a two factor factorial arranged as a randomized complete block. The main factors were kochia and wild oat pot density at either 0, 1, or 2 plants per pot. Treatment combinations resulted in species ratios of 1:1, 2:1, 1:2, and 2:2, with single species controls. Kochia biomass was reduced by &gt;70% after 3 months of competition with a single wild oat plant. Wild oat biomass was consistently impacted by intraspecific competition, demonstrating a 25 to 50% reduction at the trial end. Kochia interspecific interference with wild oat at a 2:1 ratio did reduce wild oat biomass by 50% but this trend was not consistent across experimental runs. Kochia dispersal through wild oat infestations should induce competitive stress when crop competition is considered. Three-species interference patterns to include western Canadian crops require additional study.