Avoidance and aggregation create consistent egg distribution patterns of congeneric caddisflies across spatially variable oviposition landscapes
Amongst oviparous animals, the spatial distribution of individuals is often set initially by where females lay eggs, with potential implications for populations and species coexistence. Do the spatial arrangements of oviposition sites or female behaviours determine spatial patterns of eggs? The consequences of spatial patterns may be context independent if strong behaviours drive patterns; context dependent if the local environment dominates. We tested these ideas using a guild of stream-dwelling caddisflies that oviposit on emergent rocks, focussing on genera with contrasting behaviours. In naturally occurring oviposition landscapes (riffles with emergent rocks), we surveyed the spatial arrangement and environmental characteristics of all emergent rocks, identified and enumerated egg masses on each. Multiple riffles were surveyed to test for spatially invariant patterns and behaviours. In landscapes, we tested for spatial clumping of oviposition sites exploited by each species and for segregation of congeneric species. At oviposition sites, we characterised the frequency distributions of egg masses and tested for species associations. Genus-specific behaviours produced different spatial patterns of egg masses in the same landscapes. Congregative behaviour of Ulmerochorema spp. at landscape scales and an aggregative response at preferred oviposition sites led to clumped patterns, local aggregation and species overlap. In contrast, avoidance behaviours by congeners of Apsilochorema resulted in no or weak clumping, and species segregation in some landscapes. Spatial patterns were consistent across riffles that varied in area and oviposition site density. These results suggest that quite different oviposition behaviours may be context independent, and the consequences of spatial patterns may be spatially invariant also.
KeywordsAquatic insects Congregation Rivers Spatial pattern formation Trichoptera
This research was supported by a Discovery grant from the Australian Research Council (DP 160102262). We are deeply indebted to the assistants who helped collect these data: Courtney Cummings, David Dodemaide, Alena Glaister, Ashley Macqueen and Rafael Schouton. Thanks to Peter Grant for facilitating access to Snobs Ck. Field work was carried out in conjunction with a Research Permit (No. 10007855) under the National Parks Act (Australia), from the Department of Environment, Land, Water and Planning (Victoria).
Author contribution statement
All authors conceived and designed the study. JL, BD and RL collected the data. JL carried out the numerical analyses. JL and BD led the data interpretation and writing. All authors contributed critically to writing the paper and approved the final draft.
- Anderson P (2002) Oviposition pheromones in herbivorous and carnivorous insects. In: Hilker M, Meiners T (eds) Chemoecology of insect eggs and egg deposition. Blackwell Publishing Ltd, Berlin, pp 235–263Google Scholar
- Baddeley A, Rubak E, Turner R (2016) Spatial point patterns: methodology and applications with R. Chapman and Hall/CRC Press, Boca RatonGoogle Scholar
- Besag J (1977) Contribution to the discussion of Dr Ripley’s paper. J R Stat Soc B 39:193–195Google Scholar
- Bovill WD (2013) The recruitment dynamics of stream insect larvae: oviposition and egg mortality of hydrobiosid caddisflies. PhD Thesis, The University of Melbourne, Melbourne, AustraliaGoogle Scholar
- Chesson P (2008) Quantifying and testing species coexistence mechanisms. In: Valladares F, Camacho A, Elosegui A, Gracia C, Estrada M, Senar JC, Gili JM (eds) Unity in diversity: reflections on ecology after the legacy of Ramon Margalef. Fundacion BBVA, Bilbao, pp 119–164Google Scholar
- Doak P (2000) Population consequences of restricted dispersal for an insect herbivore in a subdivided habitat. Ecology 81:1828–1841. https://doi.org/10.1890/0012-9658(2000)081[1828:PCORDF]2.0.CO;2 CrossRefGoogle Scholar
- Gordon ND, McMahon TA, Finlayson BL, Gippel CJ, Nathan RJ (2004) Stream hydrology: an introduction for ecologists, 2nd edn. John Wiley & Sons, ChichesterGoogle Scholar
- Haddow AJ, Corbet PS (1961) Entomological studies from a high tower in Mpanga Forest, Uganda. Trans R Entomol Soc Lond 113:284–300. https://doi.org/10.1111/j.1365-2311.1961.tb02288.x CrossRefGoogle Scholar
- Ives AR (1988) Aggregation and coexistence of competitors. Ann Zool Fenn 25:75–88Google Scholar
- Lounibos LP (1981) Habitat segregation among African treehole mosquitoes. Ecol Entomol 6:129–154. https://doi.org/10.1111/j.1365-2311.1981.tb00601.x CrossRefGoogle Scholar
- Miller RS (1967) Pattern and process in competition. In: Cragg JB (ed) Adv Ecol Res, vol 4. Academic Press, Cambridge, pp 1–74Google Scholar
- R Core Development Team (2017) R: a language and environment for statistical computing. R Foundation for Statistical Computing, ViennaGoogle Scholar
- Refsnider JM, Janzen FJ (2010) Putting eggs in one basket: Ecological and evolutionary hypotheses for variation in oviposition-site choice. Annu Rev Ecol Evol Syst 41:39–57. https://doi.org/10.1146/annurev-ecolsys-102209-144712 CrossRefGoogle Scholar
- Reich P (2002) The egg masses of lotic invertebrates: proximate cues for oviposition site selection and implications for larval abundance and distribution. Ph.D. Thesis, The University of Melbourne, Victoria, AustraliaGoogle Scholar
- Renwick JAA, Chew FS (1994) Oviposition behavior in Lepidoptera. Annu Rev Entomol 34:377–400. https://doi.org/10.1146/annurev.en.39.010194.002113 CrossRefGoogle Scholar
- Städler E (2002) Plant chemical cues important for egg deposition by herbivorous insects. In: Hilker M, Meiners T (eds) Chemoecology of insect eggs and egg deposition. Blackwell Science, Berlin, pp 171–204Google Scholar
- Warren-Rhodes KA, Dungan JL, Piatek J, Stubbs K, Gómez-Silva B, Chen Y, McKay CP (2007) Ecology and spatial pattern of cyanobacterial community island patches in the Atacama Desert Chile. J Geophys Res Biogeosci 112:G04S15Google Scholar