Hastings Natural History Reservation

08 Mar, 04 PM - 31 Mar, 05 PM

Proposed Research Summary Geographic range shifts resulting from anthropogenic climate change are altering species richness and biodiversity patterns worldwide. Species differ in their capacity to shift under climate change; therefore, interacting species are not shifting together. Specifically, while insects have the ability to disperse relatively quickly into new areas, their host plants may not be present, thus limiting insects? abilities to colonize new areas. For example, previous research shows that, in response to climatic changes, butterflies have already shifted their distributions poleward or to higher elevations.1 However, the projected rates for their host plants to shift are much slower.2 ,3 The primary concern being investigated here is that insects that utilize different host plants in different portions of their ranges could experience gaps or contractions in their geographic distributions under warming if populations at nearby plant transition zones can not advance into them due to strong adaptation. Erynnis propertius, the duskywing skipper, is one such species. Its geographic range extends from Mexico to Canada in conjunction with its larval host plants, members of the genus Quercus (oak).4,5 In California, coastal E. propertius populations feed on Q. agrifolia while populations in Oregon and northward feed exclusively on Q. garryana, the only available host plant there.5,6 These three Quercus species differ substantially in phenology and nutrient chemistry.7 If selection resulting in strong host plant adaptation is strong enough in E. propertius populations utilizing each of these different host plants, these populations may have decreased fitness on host plants that do not occur in their original sites, potentially hindering a northward range shift for southern E. propertius populations. Methods summary Sample collection: Gravid Erynnis propertius females will be hand caught with a butterfly net from oak meadows and will be immediately transferred to cages with host plant clippings (i.e., we also propose to collect minimal clippings from Q. agrifolia and potentially other oaks species on the property) for egg collection. The subsequent eggs will be used in the experiment described below, and the collected females will be frozen upon death, which naturally occurs after a few days. Erynnis propertius will be the only species collected; all other butterfly species will remain untouched. I have three years of experience hand collecting this species and practicing non destructive collection methods. I have worked with a variety of agencies on this project and am permitted to do this work by California Fish and Game and have applied for the proper permit from USDA APHIS. Larval performance experiment: To determine the effect of host plants on different populations of E. propertius, multiple individuals from different Quercus-dominated locales will be collected from the field and sent to the University of Notre Dame, where they will be fed leaves from potted Q. agrifolia and Q. garryana in a replicated fashion. Populations in the different regions will have individuals reared on each of the three different host plants to compare performance on their original versus the alternate host plants used by populations from the other regions. In each replicate, an individual caterpillar will be placed in an enclosure with a continuous supply of leaves from the respective Quercus treatment (n=50 replicates per treatment). All replicates in all treatments will be grown in common abiotic conditions in a greenhouse. Comparisons across treatments will be quantified using survivorship and pupal mass, an indicator of potential fecundity in Lepidoptera.8,9,10,11 Data will be analyzed using ANOVA if the assumptions of normality are met. If survivorship and pupal mass of southern populations, where Q. agrifolia is the host plant, are significantly lower on Q. garryana, these populations may be unable to successfully colonize northward to track climate change. This may result in an overall range contraction for E. propertius. Additionally, many other species will be faced with this transition in Quercus species on the West Coast. Generally, these disassociations between interacting members of ecological communities will likely lead to an overall decrease in biodiversity. Gaining a mechanistic understanding of this potential breakdown of community structure is becoming an increasingly pressing issue in conservation biology. My goal is to examine these effects of climate change in order to aid land managers in preserving biodiversity in a rapidly changing world. References 1. Parmesan, C., N. Ryrholm, C. Stefanescu, J. K. Hill, C. D. Thomas, H. Descimon, B. Huntley, L. Kaila, J. Kullberg, T. Tammaru, J. Tennent, J. A. Thomas, and M. Warren (1999), Poleward shifts in geographical ranges of butterfly species associated with regional warming, Nature 299, 579-583. 2. Davis, M. B. and R. G. Shaw 2001. Range shifts and adaptive responses to quaternary climate change. Science 292: 673-679. 3. Dullinger, S., T. Dirnb?ck and G. Grabherr 2004. Modeling climate change-driven treeline shifts: relative effects of temperature increase, dispersal and invisibility. Journal of Ecology 92 (2): 241-252. 4. Opler, P. A. 1999. Peterson Field Guide to Western Butterflies, revised edition. Houghton Mifflin Co., Boston, Mass. 5. Scott, J. A. 1986. The Butterflies of North America: A Natural History and Field Guide. Stanford, CA, Stanford University Press. 6. Guppy, C. S. and J. H. Shepard 2001. Butterflies of British Columbia. Vancouver, BC, UBC Press. 7. Knops, J. M. H., and W. D. Koenig. 1997. Site fertility and leaf nutrients of sympatric evergreen and deciduous species of Quercus in central coastal California. Plant Ecology 130:121-131. 8. Boggs, C. L. 1986. Reproductive strategies of female butterflies: variation in and constraints on fecundity. Ecological Entomology 11: 7-15. 9. Karlsson, B., and P.-O. Wickman. 1990. Increase in reproductive effort as explained by body size and resource allocation in the speckled wood butterfly, Pararge aegeria (L.). Functional Ecology 4: 609-617. 10. Oberhauser, K. S. 1997. Fecundity, lifespan and egg mass in butterflies: effects of male-derived nutrients and female size. Functional Ecology 11: 166-175. 11. Garc?a-Barros, E. 2000. Body size, egg size, and their interspecific relationships with ecological and life history traits in butterflies (Lepidoptera: Papilionidae, Hesperioidea). Biological Journal of the Linnean Society 70: 251-284.

Visit #14104 @Hastings Natural History Reservation

Approved

Under Project # 9227 | Research

Transition zones in host plant useage of Erynnis propertius

graduate_student - University of Notre Dame

Reservation Members(s)

Shannon Pelini Mar 8 - 31, 2008 (24 days)
Shannon Pelini Mar 8 - 31, 2008 (24 days)
Shannon Pelini Mar 8 - 31, 2008 (24 days)

Reserve Resources(s) | Create Invoice

Ranch House 3 Mar 8 - 31, 2008