Authors: Camille Turlure , Hans Van Dyck , Nicolas Schtickzelle and Michel Baguette

1. Resource-based habitat definition, niche overlap and conservation of two sympatric glacial relict butterflies Authors: Camille Turlure, Hans Van Dyck, Nicolas Schtickzelle and Michel Baguette Oikos 118: 950-960, 2009 Kelly Hammond

2. Outline • Introduction • Methods • Results • Discussion • Conclusion

3. Introduction • In this experiment, the authors used two butterflies to quantitatively define larval and adult resource-based habitat use of each species • They also tested the transferability of ecological profiles between the two species Lycaenahelle Proclossianaeunomia

4. Topics related to class • Niches = unique set of resources in the environment that each species uses • These two butterflies underwent sympatric speciation, which as we learned is common in invertebrates and plants • The data collected is in line with what we learned were important for protecting and managing rare and endangered species • Ecology of the species • Natural history • Status of the population • Processes that affect population size and demographics

5. Methods • Study Species • Both L. helleand P. eunomiaoccur in peat bogs and wet hay meadows • L. helle • Listed as vulnerable • Flies from early May to the end of June • Hibernates as pupa • P. eunomia • Flies only in June • Hibernates as caterpillar

6. Study siteNature reserve in southern Belgium 56 ha peat bog with six major vegetation types

7. 40 zones totaling 17 ha were selected depending on: • Presence of host plant • Succession stage of the zones

8. Caterpillar • Collected in May and July of 2005 • 107 P. eunomiafound in 87 plots • 94 L. helle found in 73 plots • Data collected at each collection site: • Moisture • Light intensity • Temperature • Using this data they created two independent variables: • CLIM1 • CLIM2

9. Adults • Population size and spatial structure was determined using a mark-release-recapture (MRR) study • Using this data they • Inferred demographic parameters • Determined frequencies of each species • At each capture site they recorded • Vegetation type • Woody edge structure • Host plant density • Tussock density • Nectar resource abundance

10. Niche breadth and overlap • Niche breadth was determined for • Larval resources • Adult resources • Space used by adults • Adult presence over time • Overlap expresses the shared space of the two species

11. ResultsCaterpillar • Both species were found primarily in rushes, wet marshes and fen grasslands • No significant difference between the three zones • P. eunomia: p=0.16 • L. helle: p=0.83 • No significant difference between the species • p=0.38

12. P. eunomiacaterpillarpresence associated with: • higher host plant abundance • Lower CLIM1 values • Higher CLIM2 values • L. helle caterpillar presence associated with: • Lower host plant • Higher values of CLIM2

13. Compared to L. helle, P. eunomiawas found in plots with: • Higher host plant coverage • Cooler temperatures • Darker conditions compared to the control

14. There was no significant difference in light conditions, moisture conditions or tussock numbers between species

15. Adults • Average recapture probability was much higher for P. eunomia, and higher for males than females for both species • Estimated population size was larger for L. helle

16. P. eunomia • Adults fed exclusively on the host plant • Flight period matched flowering of host plant • L. helle • Adults fed on 24 different plants • Flight period matched flowering periods of the various food sources

17. Both species were more frequently associated with rushes, short sedge fens and wet meadows • P. eunomia occurred significantly more frequently in rushes and fen grasslands • Host plant was more important for P. eunomia • The presence of woody edge and nectar plants were important for L. helle

18. Niche breadth and overlap • Niche breadth tended to be smaller for P. eunomia ( not significant p= 0.33 ) • Overlap was higher than 70% for most resources

19. Resource association and distribution • Host plant density, nectar abundance and woody edge presence were positively correlated and increased jointly • They were negatively correlated with tussock density

20. Discussion • Differences in habitat use can be explained by the differences in life histories • Egg laying stratgy • P. eunomia laid eggs in batches of 7 – 41 eggs • L. helle laid eggs singly • Larval habitat • P. eunomia caterpillars spent most of their time on tussock, moving to bistort only to feed • L. helle remained on the bistort throughout the larval stage • Mate location • P. eunomiamales patrol to find mates • L. hellemalesare territorial and adopt a sit-and-wait strategy • Roosting behavior • P. eunomiaroost on or near bistort • L. hellespend the night in the eastern, top part of trees

21. Niche breadth • Niche breadth was very narrow for both species • P. eunomia populations were found in nearly every zone where the host plant occured Niche overlap • Although there is a high degree of overlap, coexistence is possible without comitition • Host plants are not a limiting resource due to abundance • Adult flight periods have a limited overlap time • L. hellemales defend their territory creating space for other species

22. Conclusion • The authors showed the importance of determining the precise habitat requirements for an organism instead of only focusing on one resource that is assumed to be the most important • P. eunomia were restricted to host plant patches, while L. hellewas not • Vegetation structures provide an important component for: • Thermoregulation • Roosting • Hibrnation • Locating mates • Determining a conservation strategy requires knowledge of resources needed throughout the lifecycle, as well as behavioral observations

23. Questions?