VARIAÇÃO INTRAESPECÍFICA EM PEIXES DE RIACHO COM ÊNFASE NA ECOLOGIA TRÓFICA
DOI:
https://doi.org/10.4257/oeco.2021.2502.06Keywords:
ecological traits, feeding ecology, within-population variance, within-species variability.Abstract
Estudos que avaliam a importância da variação intraespecífica na estrutura e funcionamento de comunidades de peixes de riachos ainda são escassos. Entretanto, mensurar as características ecológicas no nível individual é de extrema importância, pois a resposta das espécies frente às variações ambientais ocorre no nível do indivíduo. Em riachos, onde as variações ambientais são constantes, essa abordagem torna-se ainda mais necessária. A variação intraespecífica em peixes de riachos pode ser mensurada a partir de diferentes características ecológicas, por exemplo, morfologia, dieta, história de vida e uso do habitat, sendo que essas características podem variar entre populações ou entre indivíduos da mesma população. O principal objetivo desse artigo foi apresentar metodologias e estudos que abordaram a variação intraespecífica na ecologia trófica de peixes de riachos. Os estudos que relacionam o papel da variação intraespecífica com a estrutura de populações e/ou comunidades foram selecionados, e suas principais implicações ecológicas, discutidas. As ferramentas de análise utilizadas para mensurar essa escala de variação são muitas, entre elas, os índices funcionais (e.g. especialização e originalidade intraespecífica), além de análises multivariadas. Os resultados gerados a partir dessas análises individuais são promissores e possuem grande potencial para explicar o funcionamento das populações e comunidades de peixes de riacho.
INTRASPECIFIC VARIATION IN STREAM FISH WITH EMPHASIS ON TROPHIC ECOLOGY: Assessing intraspecific variability in community structure and functioning are still scarce for stream-dwelling fish. However, measuring ecological traits for individuals is important since species’ response for environmental conditions occurs at the individual level, especially in streams which suffers constantly physical disturbances. Intraspecific variability can be measured for several ecological traits, such as morphology, diet, life-history, and habitat use that varies between populations or within populations. Here, we present some methods and studies that evaluated intraspecific trophic variability in stream-dwelling fish. Results revealing the role of individual variation in structure of biological populations and/or assemblages were selected, and principal issues were discussed. There are a lot of statistical tools that can test individual variation including functional indexes and multivariate analyzes. Results generated from such individual analyzes have high potential to explain the functioning of stream fish populations and communities.References
Albert, C. H., de Bello, F., Boulangeat, I., Pellet, G., Lavorel, S., & Thuiller, W. 2012. On the importance of intraspecific variability for the quantification of functional diversity. Oikos, 121(1), 116–126. DOI: 10.1111/j.1600-0706.2011.19672.x
Albert, C. H., Grassein, F., Schurr, F. M., Vieilledent, G., & Violle, C. 2011. When and how should intraspecific variability be considered in trait-based plant ecology?. Perspectives in Plant Ecology, Evolution and Systematics, 13(3), 217–225. DOI: 10.1016/j.ppees.2011.04.003
Alves, C. B. M., Pompeu, P. S., Mazzoni, R., & Brito, M. F. G. 2021. Avanços em métodos para estudos de ecologia de peixes em riachos tropicais. Oecologia Australis, 25 (2),247-246. DOI: 10.4257/oeco.2021.2502.03
Amaral, J. R., Manna, L. R., Mazzoni, R., Neres-Lima, V., Marques, P. S., El-Sabaawi, R. W., & Zandonà, E. 2021. Testing the short-term effects of a fish invader on the trophic ecology of a closely related species. Hydrobiologia, 1–14. DOI: 10.1007/s10750-020-04489-3
Araújo, M. S., Bolnick, D. I., & Layman, C. A. 2011. The ecological causes of individual specialization. Ecology Letters, 14(9), 948–958. DOI: 10.1111/j.1461-0248.2011.01662.x
Araújo, M. S., Guimarães-Jr, P. R., Svanbäck, R., Pinheiro, A., Guimarães, P., Reis, S. F., & Bolnick, D. 2008. Network analysis reveals contrasting effects of intraspecific competition on individual vs. population diets. Ecology, 89(7), 1981–1993. DOI: 10.1890/07-0630.1
Bisazza, A., & Pilastro, A. 1997. Small male mating advantage and reversed size dimorphism in poeciliid fishes. Journal of Fish Biology, 50(2), 397–406. DOI: 10.1111/j.1095-8649.1997.tb01367.x
Blanck, A., & Lamouroux, N. 2007. Large-scale intraspecific variation in life-history traits of European freshwater fish. Journal of Biogeography, 34(5), 862–875. DOI: 10.1111/j.1365-2699.2006.01654.x
Bolnick, D. I., Amarasekare, P., Araújo, M. S., Bürger, R., Levine, J. M., Novak, M., Rudolf, V. H. W., Schreiber, S. J., Urban, M. C., & Vasseur, D. A. 2011. Why intraspecific trait variation matters in community ecology. Trends in Ecology and Evolution, 26(4), 183–192. DOI: 10.1016/j.tree.2011.01.009
Bolnick, D. I., Svanbäck, R., Fordyce, J. A., Yang, L. H., Davis, J. M., Hulsey, C. D., & Forister, M. L. 2003. The ecology of individuals: incidence and implications of individual specialization. The American Naturalist, 161(1), 1–28. DOI: 10.1086/343878
Bolnick, D. I., Yang, L. H., Fordyce, J. A., Davis, J. M., & Svanbäck, R. 2002. Measuring individual‐level resource specialization. Ecology, 83(10), 2936–2941. DOI: 10.1890/0012-9658(2002)083[2936:MILRS]2.0.CO;2
Brazil-Sousa, C., Marques, R. M., & Albrecht, M. P. 2009. Segregação alimentar entre duas espécies de Heptapteridae no rio Macaé, RJ. Biota Neotropica, 9(3), 31–37. DOI: 10.1590/S1676-06032009000300002
Brito, G. J., Lima, L. G. D., Oliveira, R. E., & Pessanha, A. 2019. Intraspecific food resource partitioning in Brazilian silverside Atherinella brasiliensis (Atheriniformes: Atherinopsidae) in a tropical estuary, Brazil. Neotropical Ichthyology, 17(2), e180108. DOI: 10.1590/1982-0224-20180108
Buisson, L., Grenouillet, G., Villéger, S., Canal, J., & Laffaille, P. 2013. Toward a loss of functional diversity in stream fish assemblages under climate change. Global change biology, 19(2), 387–400. DOI: 10.1111/gcb.12056
Burton, J. I., Perakis, S. S., McKenzie, S. C., Lawrence, C. E., & Puettmann, K. J. 2017. Intraspecific variability and reaction norms of forest understorey plant species traits. Functional Ecology, 31(10), 1881–1893. DOI: 10.1111/1365-2435.12898
Capps, K. A., & Flecker, A. S. 2013. Invasive fishes generate biogeochemical hotspots in a nutrient-limited system. PLoS One, 8(1), e54093. DOI: 10.1371/journal.pone.0054093
Da Silva, J. C., Gubiani, É. A., Neves, M. P., & Delariva, R. L. 2017. Coexisting small fish species in lotic neotropical environments: evidence of trophic niche differentiation. Aquatic Ecology, 51(2), 275–288. DOI: 10.1007/s10452-017-9616-5
Dala-Corte, R. B., & De Fries, L. 2018. Inter and intraspecific variation in fish body size constrains microhabitat use in a subtropical drainage. Environmental Biology of Fishes, 101(7), 1205–1217. DOI: 10.1007/s10641-018-0769-4
Dala-Corte, R. B., Silva, E. R. D., & Fialho, C. B. 2016. Diet-morphology relationship in the stream-dwelling characid Deuterodon stigmaturus (Gomes, 1947) (Characiformes: Characidae) is partially conditioned by ontogenetic development. Neotropical Ichthyology, 14(2). DOI: 10.1590/1982-0224-20150178
Darwin, C. 1859. On the origin of species by means of natural selection. London: John Murray.
de Barros, T. F., Louvise, J., & Caramaschi, É. P. 2019. Flow gradient drives morphological divergence in an Amazon pelagic stream fish. Hydrobiologia, 833, 217–229. DOI: 10.1007/s10750-019-3902-2
de Bello, F., Lavorel, S., Albert, C.H., Thuiller, W., Grigulis, K., Dolezal, J., Janecek, S., & Leps, J. 2011. Quantifying the relevance of intraspecific trait variability for functional diversity. Methods in Ecology and Evolution, 2(2), 163–174. DOI: 10.1111/j.2041-210X.2010.00071.x
Des Roches, S., Post, D. M., Turley, N. E., Bailey, J. K., Hendry, A. P., Kinnison, M. T., Schweitzer, J. A., & Palkovacs, E. P. 2018. The ecological importance of intraspecific variation. Nature ecology & evolution, 2(1), 57–64. DOI: 10.1038/s41559-017-0402-5
El‐Sabaawi, R. W., Zandonà, E., Kohler, T. J., Marshall, M. C., Moslemi, J. M., Travis, J., López-Sepulcre, A., Ferriére, R., Pringle, C. M., Thomas, S. A., Reznick, D. N., & Flecker, A. S. 2012. Widespread intraspecific organismal stoichiometry among populations of the Trinidadian guppy. Functional Ecology, 26(3), 666–676. DOI: 10.1111/j.1365-2435.2012.01974.x
Evangelista, C., Boiche, A., Lecerf, A., & Cucherousset, J. 2014. Ecological opportunities and intraspecific competition alter trophic niche specialization in an opportunistic stream predator. Journal of Animal Ecology, 83(5), 1025–1034. DOI: 10.1111/1365-2656.12208
Evangelista, C., Lecerf, A., Britton, J. R., & Cucherousset, J. 2017. Resource composition mediates the effects of intraspecific variability in nutrient recycling on ecosystem processes. Oikos, 126(10), 1439–1450. DOI: 10.1111/oik.03787
Fletcher, D. E., Lindell, A. H., Stillings, G. K., Mills, G. L., Blas, S. A., & McArthur, J. V. 2015. Trophic variation in coastal plain stream predatory fishes. Southeastern Naturalist, 14(2), 373-396. DOI: 10.1656/058.014.0217
Galindo-Villegas, J., & Sosa-Lima, F. 2002. Gonopodial system review and a new fish record of Poeciliopsis infans (Cyprinodontiformes: Poeciliidae) for Lake Patzcuaro, Michoacan, central Mexico. Revista de Biologia Tropical, 50(3–4), 1151–1157.
Griffiths, J. I., Childs, D. Z., Bassar, R. D., Coulson, T., Reznick, D. N., & Rees, M. 2020. Individual differences determine the strength of ecological interactions. Proceedings of the National Academy of Sciences, 117(29), 17068–17073. DOI: 10.1073/pnas.2000635117
Grossman, G. D., & Freeman, M. C. 1987. Microhabitat use in a stream fish assemblage. Journal of Zoology, 212(1), 151–176. DOI: 10.1111/j.1469-7998.1987.tb05121.x
Guo, Z., Liu, J., Lek, S., Li, Z., Zhu, F., Tang, J., & Cucherousset, J. 2014. Trophic niche differences between two congeneric goby species: evidence for ontogenetic diet shift and habitat use. Aquatic Biology, 20(1), 23–33. DOI: 10.3354/ab00530
Harding, H. R., Gordon, T. A., Eastcott, E., Simpson, S. D., & Radford, A. N. 2019. Causes and consequences of intraspecific variation in animal responses to anthropogenic noise. Behavioral Ecology, 30(6), 1501–1511. DOI: 10.1093/beheco/arz114
Hood, J. M., Vanni, M. J., & Flecker, A. S. 2005. Nutrient recycling by two phosphorus-rich grazing catfish: the potential for phosphorus-limitation of fish growth. Oecologia, 146(2), 247–257. DOI: 10.1007/s00442-005-0202-5
Hopper, G. W., & Tobler, M. 2016. Patterns of trophic resource use and individual specialization in two species of darters (Etheostoma: Percidae). Evolutionary Ecology Research, 17(1), 53–73.
Hurd, P. L. 1997. Cooperative signalling between opponents in fish fights. Animal Behaviour, 54(5), 1309–1315. DOI: 10.1006/anbe.1997.0531
Iguchi, K. I., Matsubara, N., Yodo, T., & Maekawa, K. 2004. Individual food niche specialization in stream-dwelling charr. Ichthyological Research, 51(4), 321–326. DOI: 10.1007/s10228-004-0237-3
Kerr, N. R., & Ingram, T. 2021. Personality does not predict individual niche variation in a freshwater fish. Behavioral Ecology, 32(1), 159–167. DOI: 10.1093/beheco/araa117
Kliemann, B. C. K., Baldasso, M. C., Pini, S. F. R., Makrakis, M. C., Makrakis, S., & Delariva, R. L. 2019. Assessing the diet and trophic niche breadth of an omnivorous fish (Glanidium ribeiroi) in subtropical lotic environments: intraspecific and ontogenic responses to spatial variations. Marine and Freshwater Research, 70(8), 1116–1128. DOI: 10.1071/MF18149
Kokubun, É. E., Bonato, K. O., Burress, E. D., & Fialho, C. B. 2018. Diet and body shape among populations of Bryconamericus iheringii (Otophysi: Characidae) across the Campos Sulinos ecosystem. Neotropical Ichthyology, 16(4). DOI: 10.1590/1982-0224-20170167
Lavorel, S., & Garnier, E. 2002. Predicting changes in community composition and ecosystem functioning from plant traits: revisiting the Holy Grail. Functional Ecology, 16(5), 545–556. DOI: 10.1046/j.1365-2435.2002.00664.x
Lichstein, J. W., Dushoff, J., Levin, S. A., & Pacala, S. W. 2007. Intraspecific variation and species coexistence. The American Naturalist, 170(6), 807–818. DOI: 10.1086/522937
Lobón-Cerviá, J., & Bennemann, S. 2000. Temporal trophic shifts and feeding diversity in two sympatric, neotropical, omnivorous fishes: Astyanax bimaculatus and Pimelodus maculatus in Rio Tibagi (Paraná, Southern Brazil). Archiv für Hydrobiologie, 149(2), 285–306. DOI: 10.1127/archiv-hydrobiol/149/2000/285
Łomnicki, A. 1980. Regulation of population density due to individual differences and patchy environment. Oikos, 185–193. DOI: 10.2307/3544426
Mabee, P. M., Olmstead, K. L., & Cubbage, C. C. 2000. An experimental study of intraspecific variation, developmental timing, and heterochrony in fishes. Evolution, 54(6), 2091–2106. DOI: 10.1111/j.0014-3820.2000.tb01252.x
Magurran, A. E. 1986. Individual differences in fish behaviour. In: Pitcher, T. J. (Ed.). The Behavior of Teleost Fishes. pp. 338–365. Croon Helm Press. London
Manna, L. R., Rezende, C. F., & Mazzoni, R. 2012. Plasticity in the diet of Astyanax taeniatus in a coastal stream from Southeast Brazil. Brazilian Journal of Biology, 72(4), 919–928. DOI: 10.1590/S1519-69842012000500020
Manna, L. R., Rezende, C. F., & Mazzoni, R. 2017. Effect of body size on microhabitat preferences in stream‐dwelling fishes. Journal of Applied Ichthyology, 33(2), 193–202. DOI: 10.1111/jai.13320
Manna, L. R., Villéger, S., Rezende, C. F., & Mazzoni, R. 2019. High intraspecific variability in morphology and diet in tropical stream fish communities. Ecology of Freshwater Fish, 28(1), 41–52. DOI: 10.1111/eff.12425
Martelo, J., Grossman, G. D., & Filomena Magalhães, M. 2013. Extrinsic and intrinsic factors influence daily activity of a Mediterranean cyprinid. Ecology of Freshwater Fish, 22(2), 307–316. DOI: 10.1111/eff.12027
Matthews, B., Marchinko, K. B., Bolnick, D. I., & Mazumder, A. 2010. Specialization of trophic position and habitat use by sticklebacks in an adaptive radiation. Ecology, 91(4), 1025–1034. DOI: 10.1890/09-0235.1
McLaughlin, R. L. 2001. Behavioural diversification in brook charr: adaptive responses to local conditions. Journal of Animal Ecology, 70(2), 325–337. DOI: 10.1111/j.1365-2656.2001.00491.x
Mello, F. T., Iglesias, C., Borthagaray, A. I., Mazzeo, N., Vilches, J., Larrea, D., & Ballabio, R. 2006. Ontogenetic allometric coefficient changes: implications of diet shift and morphometric traits in Hoplias malabaricus (Bloch) (Characiforme, Erythrinidae). Journal of Fish Biology, 69(6), 1770–1778. DOI: 10.1111/j.1095-8649.2006.01245.x
Mitchell, R. M., & Bakker, J. D. 2014. Quantifying and comparing intraspecific functional trait variability: a case study with Hypochaeris radicata. Functional Ecology, 28(1), 258–269. DOI: 10.1111/1365-2435.12167
Mouillot, D., Graham, N. A. J., Villéger, S., Mason, N. W. H., & Bellwood, D. R. 2013. A functional approach reveals community responses to disturbances. Trends in Ecology and Evolution, 28(3), 167–177. DOI: 10.1016/j.tree.2012.10.004
Nakano, S., Kawaguchi, Y., Taniguchi, Y., Miyasaka, H., Shibata, Y., Urabe, H., & Kuhara, N. 1999. Selective foraging on terrestrial invertebrates by rainbow trout in a forested headwater stream in northern Japan. Ecological Research, 14(4), 351–360. DOI: 10.1046/j.1440-1703.1999.00315.x
Neves, M. P., Costa‐Pereira, R., Delariva, R. L., & Fialho, C. B. 2021. Seasonality and interspecific competition shape individual niche variation in co‐occurring tetra fish in Neotropical streams. Biotropica, 53(1), 329–338. DOI: 10.1111/btp.12879
Pavoine, S., & Izsák, J. 2014. New biodiversity measure that includes consistent interspecific and intraspecific components. Methods in Ecology and Evolution, 5(2), 165–172. DOI: 10.1111/2041-210X.12142
Perazzo, G. X., Corrêa, F., Calviño, P., Alonso, F., Salzburger, W., & Gava, A. 2019. Shape and size variation of Jenynsia lineata (Jenyns 1842) (Cyprinodontiformes: Anablepidae) from different coastal environments. Hydrobiologia, 828(1), 21–39. DOI: 10.1007/s10750-018-3794-6
Pitcher, T. E., & Evans, J. P. 2001. Male phenotype and sperm number in the guppy (Poecilia reticulata). Canadian Journal of Zoology, 79(10), 1891–1896. DOI: 10.1139/z01-142
Post, D. M., Palkovacs, E. P., Schielke, E. G., & Dodson, S. I. 2008. Intraspecific variation in a predator affects community structure and cascading trophic interactions. Ecology, 89(7), 2019–2032. DOI: 10.1890/07-1216.1
Py-Daniel, L. H. R., & Fernandes, C. C. 2005. Dimorfismo sexual em Siluriformes e Gymnotiformes (Ostariophysi) da Amazônia. Acta Amazonica, 35(1), 97–110.
Rick, I. P., & Bakker, T. C. 2008. Color signaling in conspicuous red sticklebacks: do ultraviolet signals surpass others?. BMC Evolutionary Biology, 8(1), 1–9. DOI: 10.1186/1471-2148-8-189
Rincón, P. A., Bastir, M., & Grossman, G. D. 2007. Form and performance: body shape and prey-capture success in four drift-feeding minnows. Oecologia, 152(2), 345–355. DOI: 10.1007/s00442-006-0651-5
Rodrigues, R. R., Carvalho, L. N., Zuanon, J., & Del-Claro, K. 2009. Color changing and behavioral context in the Amazonian Dwarf Cichlid Apistogramma hippolytae (Perciformes). Neotropical Ichthyology, 7(4), 641–646. DOI: 10.1590/S1679-62252009000400013
Sánchez-Hernández, J. 2016. Do age-related changes in feeding habits of brown trout alter structural properties of food webs?. Aquatic Ecology, 50(4), 685–695. DOI: 10.1007/s10452-016-9586-z
Sánchez-Hernández, J., & Cobo, F. 2013. Foraging behaviour of brown trout in wild populations: can population density cause behaviourally-mediated foraging specializations?. Animal Biology, 63(4), 425–450. DOI: 10.1163/15707563-00002423
Sánchez-Hernández, J., & Cobo, F. 2016. Ontogenetic shifts in terrestrial reliance of stream-dwelling brown trout. Journal of Limnology, 75(2). DOI: 10.4081/jlimnol.2016.1322
Sánchez-Hernández, J., & Cobo, F. 2018. Modelling the factors influencing ontogenetic dietary shifts in stream-dwelling brown trout (Salmo trutta). Canadian Journal of Fisheries and Aquatic Sciences, 75(4), 590–599. DOI: 10.1139/cjfas-2017-0021
Santos, T. D. A., Terra, B. D. F., Zandona, E., Santaella, S. T., & Rezende, C. F. 2016. Phosphorus body content in an herbivorous fish in environments with different trophic state. Journal of Limnology, 75(3), 439–444. DOI: 10.4081/jlimnol.2016.1202
Smith, J. A., Baumgartner, L. J., Suthers, I. M., & Taylor, M. D. 2011. Generalist niche, specialist strategy: the diet of an Australian percichthyid. Journal of fish Biology, 78(4), 1183–1199. DOI: 10.1111/j.1095-8649.2011.02926.x
Svanbäck, R., & Bolnick, D. I. 2007. Intraspecific competition drives increased resource use diversity within a natural population. Proceedings of the Royal Society, 274(1611), 839–844. DOI: 10.1098/rspb.2006.0198
Svanbäck, R., & Persson, L. 2004. Individual diet specialization, niche width and population dynamics: implications for trophic polymorphisms. Journal of Animal Ecology, 73(5), 973–982.
Teresa, F. B., Rodrigues-Filho, C. A. S, & Leitão, R. P. 2021. Diversidade funcional de comunidades de peixes de riachos. Oecologia Australis, 25 (2), 416-433. DOI: 10.4257/oeco.2021.2502.12
Tunney, T. D., & Steingrímsson, S. Ó. 2012. Foraging mode variation in three stream‐dwelling salmonid fishes. Ecology of Freshwater Fish, 21(4), 570–580. DOI: 10.1111/j.1600-0633.2012.00577.x
Van Valen, L. 1965. Morphological variation and width of ecological niche. The American Naturalist, 99(908), 377–390. DOI: 10.1086/282379
Villéger, S., Brosse, S., Mouchet, M., Mouillot, D., & Vanni, M. J. 2017. Functional ecology of fish: current approaches and future challenges. Aquatic Sciences, 79(4), 783–801. DOI: 10.1007/s00027-017-0546-z
Villéger, S., Grenouillet, G., Suc, V., & Brosse, S. 2012. Intra‐and interspecific differences in nutrient recycling by European freshwater fish. Freshwater Biology, 57(11), 2330–2341. DOI: 10.1111/fwb.12009
Violle, C., Enquist, B. J., McGill, B. J., Jiang, L., Albert, C. H., Hulshof, C., Jung, V., & Messier, J. 2012. The return of the variance: intraspecific variability in community ecology. Trends in Ecology and Evolution, 27(4), 244–252. DOI: 10.1016/j.tree.2011.11.014
Violle, C., Navas, M. L., Vile, D., Kazakou, E., Fortunel, C., Hummel, I., & Garnier, E. 2007. Let the concept of trait be functional!. Oikos, 116(5), 882–892. DOI: 10.1111/j.0030-1299.2007.15559.x
Wagner, C. E., McIntyre, P. B., Buels, K. S., Gilbert, D. M., & Michel, E. 2009. Diet predicts intestine length in Lake Tanganyika’s cichlid fishes. Functional Ecology, 23(6), 1122–1131. DOI: 10.1111/j.1365-2435.2009.01589.x
Warbanski, M. L., Marques, P., Frauendorf, T. C., Phillip, D. A., & El‐Sabaawi, R. W. 2017. Implications of guppy (Poecilia reticulata) life‐history phenotype for mosquito control. Ecology and evolution, 7(10), 3324–3334. DOI: 10.1002/ece3.2666
Weise, M. J., Harvey, J. T., & Costa, D. P. 2010. The role of body size in individual-based foraging strategies of a top marine predator. Ecology, 91(4),1004–1015. DOI: 10.1890/08-1554.1
Wilson, A. D., & McLaughlin, R. L. 2007. Behavioural syndromes in brook charr, Salvelinus fontinalis: prey-search in the field corresponds with space use in novel laboratory situations. Animal Behaviour, 74(4), 689–698. DOI: 10.1016/j.anbehav.2007.01.009
Wood, B. M., & Bain, M. B. 1995. Morphology and microhabitat use in stream fish. Canadian Journal of Fisheries and Aquatic Sciences, 52(7), 1487–1498. DOI: 10.1139/f95-143
Zaccarelli, N., Bolnick, D. I., & Mancinelli, G. 2013. RInSp: an R package for the analysis of individual specialization in resource use. Methods in Ecology and Evolution, 4(11), 1018–1023. DOI: 10.1111/2041-210X.12079
Zhao, T., Villéger, S., Lek, S., & Cucherousset, J. 2014. High intraspecific variability in the functional niche of a predator is associated with ontogenetic shift and individual specialization. Ecology and Evolution, 4(24), 4649–4657. DOI: 10.1002/ece3.1260
