Pianka's Niche Overlap Research Articles

Dietary competition between the alien Asian Musk Shrew (Suncus murinus) and a re‐introduced population of Telfair's Skink (Leiolopisma telfairii)

Re-introduction of rare species to parts of their historical range is becoming increasingly important as a conservation strategy. Telfair's Skinks (Leiolopisma telfairii), once widespread on Mauritius, were until recently found only on Round Island. There it is vulnerable to stochastic events, including the introduction of alien predators that may either prey upon it or compete for food resources. Consequently, skinks have been introduced to Ile aux Aigrettes, another small Mauritian island that has been cleared of rats. However, the island has been invaded by Asian Musk Shrews (Suncus murinus), a commensal species spread by man well beyond its natural Asian range. Our aim was to use next-generation sequencing to analyse the diets of the shrews and skinks to look for niche competition. DNA was extracted from skink faeces and from the stomach contents of shrews. Application of shrew- and skink-specific primers revealed no mutual predation. The DNA was then amplified using general invertebrate primers with tags to identify individual predators, and then sequenced by 454 pyrosequencing. 119 prey MOTUs (molecular taxonomic units) were isolated, although none could be identified to species. Seeding of cladograms with known sequences allowed higher taxonomic assignments in some cases. Although most MOTUs were not shared by shrews and skinks, Pianka's niche overlap test showed significant prey overlap, suggesting potentially strong competition where food resources are limited. These results suggest that removal of the shrews from the island should remain a priority.

Seedling recruitment factors in low‐diversity Hawaiian wet forest: towards global comparisons among tropical forests

Recruitment limitations determine forest community regeneration patterns. Source limitation and dispersal limitation contribute to overall seed limitation, while environmental conditions and habitat associations influence establishment limitation. Several hypotheses have made contradictory predictions for how the relative importance of these limitations should vary with diversity. However, comparative data have not been available for low‐diversity tropical forests. We quantified recruitment limitations using 2.5 yrs of seed rain and seedling distribution data collected within a 4 ha forest dynamics plot in low‐diversity native‐dominated Hawaiian wet forest. We further quantified seedling irradiance and substrate habitat associations and niche overlap (using Pianka's niche overlap index). Additionally, we compared recruitment limitations and the frequency of seedling habitat associations across forests using the few available published data from sites employing similar field and analytical methods. In Hawaiian wet forest, seed dispersal more strongly limited recruitment than did establishment limitation across species, with 11 of 18 species completely seed limited (i.e., no seeds found). However, the relative importance of limitations varied greatly among species. For the three most abundant species, habitat conditions more strongly limited regeneration than did seed arrival, especially for the dominant canopy species, Metrosideros polymorpha, which was not seed limited. Most species were significantly associated with specific ranges of irradiance and/or substrates. Although habitat associations may indicate niche differentiation, Hawaiian species also showed significant niche overlap. Across the three forests compared, community‐wide mean seed and establishment limitation values were similar, despite wide variation in diversity. However, recruitment limitations differed strongly among species within forests due to species' life‐history differences. While seed limitation in Hawaiian forest was as high as in high‐diversity forests, mechanisms may differ; seed limitation in Hawaii may arise from loss of pollinators and dispersers rather than from a high proportion of rare species as occurs in high‐diversity forests. The strong habitat associations in Hawaiian forest relative to high‐diversity forests supported theoretical expectations that lower species diversity should increase the importance of habitat associations. However, these habitat associations were not linked to niche differentiation in Hawaii. Our findings suggest that high recruitment limitation may facilitate coexistence despite niche overlap in low‐diversity Hawaiian forest.

Characteristics of plant niche under different restoration measures in Ili desert grassland of Xinjiang Uygur Autonomous Region

Serious degradation of spring and autumn sagebrush desert steppes was a bottleneck for developing seasonal animal husbandry in northern Xinjiang.In order to restore the sagebrush desert steppes,grazing was seasonally banned or long-term prohib-ited and grassland reseeding was adopted.In this study,the characteristics of niche breadth and niche overlap of 16 Ili desert grassland species were analyzed.The selected grasslands were seasonal grazing banned,long-term grazing prohibited,reseeded and grazed freely.The dominant species(Seriphidium transiliense) had the largest niche breadth,expect in reseeded grassland.S.transil-iense niche breadths in freely grazed grassland,long-term grazing prohibited grassland,seasonally grazing banned grassland were 1.037,1.101 and 1.070,respectively.In also the reseeded grassland,Stipa sp.had the largest niche breadth(0.798).While higher Pianka niche overlap occurred in high niche breadth species,the highest niche overlap occurred in low niche breadth species.Fur-thermore,niche proportion similarity and overlap between S.transiliense and Ceratoides arenarius were high in all four grasslands.This showed an intense interspecies competition for resources between the two species.

Is the red spotted green frog Hypsiboas punctatus (Anura: Hylidae) selecting its preys? The importance of prey availability

The study of the feeding ecology of amphibians is an old issue in herpetology. Notwithstanding, the lack of food resources data in many studies of amphibians feeding has lead to partial understanding of frog feeding strategies. In this study we evaluate the trophic selectivity of a red spotted green frog (Hypsiboas punctatus) population from a Middle Paraná River floodplain pond in Argentina, and discuss the importance of prey availability data when interpreting results from diet analysis. We analyzed the gut contents of 47 H. punctatus adults and compared frog's diet with the environmental food resources. Prey availability was estimated by systematically seep-netting the microhabitat where anurans were localized foraging. We identified 33 taxonomic categories from gastrointestinal contents. Numerically, the most important prey categories were dipterans, followed by hemipterans, homopterans and coleopterans. The diet similarity between males and females was high and no statistical differences in diet composition were found. The most abundant food resources in the environment were dipterans, coleopterans, homopterans and collembolans. In order to assess whether frogs were selecting their preys, we calculated Pianka's niche overlap index and Jacobs' electivity index comparing gut contents to prey availability data. Trophic niche overlap was medium but significantly higher than expected by chance. The electivity index indicated that H. punctatus foraged dipterans slightly above their environmental abundance. Among the secondary preys, hemipterans were foraged selectively, homopterans were consumed in the same proportion to their occurrence in the environment, coleopterans were foraged quite under their availability and collembolans were practically ignored by frogs. Without food resources data, H. punctatus could be classified as a specialist feeder, but dipterans also were quite abundant in the environment. Our results show that H. punctatus fit better as a generalist feeder, foraging on their main food item and some secondary preys in similar proportion to their environmental availability; even though other secondary preys are being selectively preferred or ignored by frogs. Our data illustrate the importance of including the resource availability data on diet studies to improve the understanding of amphibian feeding ecology.

Niche characteristics of rodents by diverse disturbance in Alashan desert, Inner Mongolia, China

Four diverse disturbance types, namely, farmland, rotationally grazed grassland, overgrazed grassland and forbidden grazing grassland, were identified in the Alashan desert region of Inner Mongolia. Rodents were sampled in April, July and October in 2002 and 2003 using the trap-day method. Their spatial and temporal niches among the four disturbance types were assessed using the Shannon-Wiener niche breadth index and the Pianka niche overlap index. The Shannon-Wiener niche breadth index was the highest for Allactaga sibirica and Meriones meridianus (0.925 and 0.908, respectively), intermediate for Cricetulus eversmanni, Phodopus roborovskii and Citellus dauricus (0.789, 0.782 and 0.711, respectively), and lowest for Cardiocranius paradoxus (0.003). The Pianka niche overlap indices of six-paired species were the highest and varied from 0.900 to 1.000, suggesting their spatial niche overlapped almost completely. Conversely, the spatial niche overlap index for Meriones unguiculatus, Cardiocranius paradoxus, and Salpingotus kozlovi was zero, thus indicating a complete absence of competition among them. In addition, the temporal niche breadth and overlap indices varied greatly in relation to disturbance types and season. The level of temporal niche overlap in spring and autumn was low while in summer it was high. For all disturbance types and for each season, the temporal niche overlap index of Meriones meridianus and Cricetulus barabansis was always highest but for Meriones unguiculatus and Salpingotus kozlovi always lowest.

Food niche overlap between sympatric potential competitors increases with habitat alteration at different trophic levels in rain-forest reptiles (omnivorous tortoises and carnivorous vipers)

Comparisons of sympatric reptile species were used to assess the variation in niche overlap for food between potential competitors at different trophic levels. Omnivorous tortoises and carnivorous vipers inhabiting the rain-forest region of West Africa were used as study models. Food niche overlap between species increased with habitat alteration in both the independent study systems: tortoises (Kinixys homeana and Kinixys erosa) and vipers (Bitis gabonica and Bitis nasicornis) showed lower values of Pianka's niche overlap index in the pristine habitat than in the altered habitat, and these differences in overlap values did not depend on chance after Monte Carlo simulations. There were higher inter-habitat food niche overlaps within-species than between-species. Permutation tests (assessed after 5000 iterations) revealed that, for both study systems, the P-values became significantly smaller with fewer resource states, thus showing the niche overlap between species really increases after habitat alteration. The observed increases in food niche overlap between species accomplished with rain-forest habitat degradation in turn may be predicted to have cumulative effects on reducing the level of forest biodiversity.

Prey preference and niche overlap of ringed seals Phoca hispida and harp seals P. groenlandica in the Barents Sea

Ringed seals Phoca hispida and harp seals P. groenlandica were collected for diet analysis along the ice edge in the Barents Sea to investigate possible niche overlap between these 2 seal species. The diet analysis is based on contents from stomachs and intestines. A resource availability survey was conducted concurrently based on an echo survey combined with demersal and pelagic trawling. This survey showed that the potential prey biomass was dominated by pelagic crustaceans (99% of total biomass) -principally Themisto libellula and Thyssanoessa spp. Despite the prevalence of these crustaceans both seal species showed a strong preference for fish of various species, which constituted only 1 % of the biomass in the area. The most common fish in their diet was polar cod Boreogadus saida, which had a Manly's prey preference index of 0.87 for ringed seals and 0.42 for harp seals. Pianka's niche overlap index for the 2 seal species in this area was 0.985, indicating an almost complete niche overlap. However, harp seals prey on significantly larger polar cod than ringed seals, and the larger cod were distributed in deeper water than smaller cod. Thus it appears that the 2 seal species exploit different fractions of the same resource.

Niche Parameters and Species Richness

This study examines how spatial niche parameters change as functions of species richness. The basis of the study was the partitioning of space by a community of small mammals in eastern Australian coastal heathland. Live—trapping was carried out in 13 habitat patches with two to seven coexisting species of small mammals on a 6.4—ha study area. Data from the 1st 2 mo of this 5—yr study are analyzed in detail. Spatial niche parameters were calculated using trapping stations as resource states. Mean niche breadth and mean niche overlap were negative functions of species richness while mean niche separation was a positive function of species richness. Spatial niche separation was estimated using nearest—neighbor analysis. Total spatial niche overlap increased to a peak and then decreased as the number of species increased. The field results were tested against two null hypotheses of noninteraction between species, one with and one without habitat selection, while a third considered the species—abundance effect using equally abundant species. The simulation values showed similar trends for the first three parameters and a continued increase for total overlap. However, field values had significantly steeper slopes, and parameter values at the extremities were usually significantly different form simulated values. Simulated niche parameters became independent of species richness when species were equally abundant, but showed increasing dependence as habitat partitioning and then microhabitat partitioning were introduced into the models. The results support Pianka's niche overlap hypthesis; mean overlaps were significantly higher than expected with a few species and significantly lower with many species, suggesting diffuse competition. Unsaturated patches showed an opposite effect, when space did not appear to be limiting, strongly implying that interspecific interactions play an important role in limiting the closeness of species packing in this community. Additional species are accommodated by significantly increasing mean spatial niche separation, thus decreasing mean spatial overlap. The rate of change in mean spatial niche breadth is not significantly different from the simulated rates.

Comments on Abrams' Test of Pianka's Niche Overlap Hypothesis

Previous articleNext article No AccessNotes and CommentsComments on Abrams' Test of Pianka's Niche Overlap HypothesisBrian G. Williams and F. F. BanyikwaBrian G. Williams Search for more articles by this author and F. F. Banyikwa Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The American Naturalist Volume 117, Number 5May, 1981 Published for The American Society of Naturalists Article DOIhttps://doi.org/10.1086/283758 Views: 6Total views on this site Citations: 4Citations are reported from Crossref Copyright 1981 The University of ChicagoPDF download Crossref reports the following articles citing this article:Thomas G Aubier Positive density dependence acting on mortality can help maintain species-rich communities, eLife 9 (Jun 2020).https://doi.org/10.7554/eLife.57788Dale E. Taneyhill METAPOPULATION DYNAMICS OF MULTIPLE SPECIES: THE GEOMETRY OF COMPETITION IN A FRAGMENTED HABITAT, Ecological Monographs 70, no.44 (Nov 2000): 495–516.https://doi.org/10.1890/0012-9615(2000)070[0495:MDOMST]2.0.CO;2Yap Siaw-Yang Food resource utilization partitioning of fifteen fish species at Bukit Merah Reservoir, Malaysia, Hydrobiologia 157, no.22 (Jan 1988): 143–160.https://doi.org/10.1007/BF00006967Robert D. Holt Density-independent mortality, non-linear competitive interactions, and species coexistence, Journal of Theoretical Biology 116, no.44 (Oct 1985): 479–493.https://doi.org/10.1016/S0022-5193(85)80084-9

Niche Overlap Among Foliage-Gleaning Birds: Support for Pianka's Niche Overlap Hypothesis

Previous articleNext article No AccessNotes and CommentsNiche Overlap Among Foliage-Gleaning Birds: Support for Pianka's Niche Overlap HypothesisKurt A. RusterholzKurt A. Rusterholz Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The American Naturalist Volume 117, Number 3Mar., 1981 Published for The American Society of Naturalists Article DOIhttps://doi.org/10.1086/283721 Views: 12Total views on this site Citations: 6Citations are reported from Crossref Copyright 1981 The University of ChicagoPDF download Crossref reports the following articles citing this article:Cody K. Porter, Jimena Golcher‐Benavides, Craig W. Benkman Seasonal patterns of dietary partitioning in vertebrates, Ecology Letters 13 (Sep 2022).https://doi.org/10.1111/ele.14100Faith Inman-Narahari, Rebecca Ostertag, Susan Cordell, Christian P. Giardina, Kehauwealani Nelson-Kaula, Lawren Sack Seedling recruitment factors in low-diversity Hawaiian wet forest: towards global comparisons among tropical forests, Ecosphere 4, no.22 (Feb 2013): art24.https://doi.org/10.1890/ES12-00164.1Rutledge S Boyes, Michael R Perrin Generalists, specialists and opportunists: niche metrics of Poicephalu s parrots in southern Africa, Ostrich 80, no.22 (Mar 2010): 93–97.https://doi.org/10.2989/OSTRICH.2009.80.2.5.832ARIEL A. FARIAS, FABIAN M. JAKSIC El Niño events, the lean versus fat scenario, and long-term guild dynamics of vertebrate predators in a South American semiarid ecosystem, Austral Ecology 32, no.22 (Mar 2007): 225–238.https://doi.org/10.1111/j.1442-9993.2007.01684.xR. MACNALLY A winter's tale: Among-year variation in bird community structure in a southeastern Australian forest, Austral Ecology 21, no.33 (Sep 1996): 280–291.https://doi.org/10.1111/j.1442-9993.1996.tb00610.xD. A. Bruns, G. W. Minshall Macroscopic Models of Community Organization: Analyses of Diversity, Dominance, and Stability in Guilds of Predaceous Stream Insects, (Jan 1983): 231–264.https://doi.org/10.1007/978-1-4613-3775-1_10

Density-Independent Mortality and Interspecific Competition: A Test of Pianka's Niche Overlap Hypothesis

A review of the relationship between nonselective density-independent mortality (DIM) and the maximum overlap of competitors in the Lotka-Volterra model fails to support Pianka's niche-overlap hypothesis. An analysis of a simple model of exploitative competition reveals that higher DIM may increase the niche separation required for competing species to coexist. This is the opposite of the relationship proposed by Pianka. Confusion regarding this issue may have arisen from a failure to define the intensity of competition. Several possible meanings of this term are presented and discussed in relation to the evolution of interference competition. The nature of correlations between intrinsic rate of increase and competitive ability is especially important in determining whether DIM will ever make coexistence of competitors more likely.