Research Interests

Pipevine swallowtails

Work on the pipevine swallowtail has primarily focused on geographic variation in life history traits, specifically egg clustering by females and aggregative feeding of larvae, and the evolution of chemical sequestration. Clutch size is an important life history trait because it represents a proportion of a females potential fecundity that she invests in a single oviposition event. Work thus far has demonstrated that aggregative feeding is beneficial to larvae in some populations because larger feeding aggregations manipulate hostplant quality in a way that accelerates larval growth rates. Fast growth is important to early instar larvae because these are the stages when larvae are most susceptable to natural enemies as well as abiotic factors, such as temperature. Furthermore, work thus far has demonstrated that the geographic variation in clutch size "matches" geographic variation in this benefit (i.e., in populations with small clutch sizes the benefit of accelerated growth associated with large feeding aggregations is absent). A phylogeographic study of the pipevine swallowtail suggests that the populations with the largest clutch size (those in California) are of recent origin, indicating a recent modification in this life history trait.

As larvae, pipevine swallowtails sequester toxic alkaloids called aristolochic acids from their Aristolochia hostplants. As a result, both larvae and adults are chemically defended against many predators. Consequentially, many palatable species of butterflies mimic the appearance of the pipevine swallowtail. Currently, various aspects of the chemical ecology of the pipevine swallowtail are being investigated, including the heritability of sequestration ability, sequestration as a quantitative trait, geographic variation in sequestration ability and host plant toxicity, geographic patterns of mimicry, and trade-offs associated with chemical defense. Recently, we have been investigating the interaction between optimal caterpillar group size and larval toxicity while considering the costs associated with toxicity and the level of predator threat.

Read on ...(Fordyce et al. 2010; Fordyce & Nice 2008; Fordyce 2006; Nice & Fordyce 2006; Fordyce et al. 2005; Fordyce 2003; Fordyce & Nice 2003; Fordyce & Shapiro 2003; Fordyce & Agrawal 2001; Fordyce 2001; Fordyce 2000)

Pipevine swallowtail (Battus philenor)

Some mimics of the pipevine swallowtail

   

 

 

Significance of wing pattern variation

Field experiments using computer generated models indicate the significance of wing patterns as mate recognition signals.

 

Lycaenid diversity

The family Lycaenidae (blues, coppers, hairstreaks, and metalmarks) is the most species rich group of butterflies, comprising 30 - 50% of all butterfly species. Our work on the lycaenids includes various aspects of their ecology (e.g., host plant preference, ant mutualisms, etc), behavior (e.g., mate selection), and population biology (e.g., local adaptation, gene flow, and phylogenetics).

Most of the work has focused on the Lycaeides species complex in collaboration with Chris Nice at Texas State Univeristy, San Marcos, Zach Gompert at the University of Wyoming, and Matt Forister at the University of Nevada, Reno. The objective of this work is to examine evolutionary processes at multiple scales and identify the factors that drive differentiation and evolution of morphological, ecological, behavioral, and genetic discontinuities.

A continental scale survey of morphological variation validates the current taxonomy of 2 species in North America, Lycaeides idas and L. melissa. However, a survey of genetic variation identified 3 major clades. Neither morphospecies is monophyletic and mtDNA haplotypes are shared between them.

We have examined the mechanisms by which reproductive isolation may evolve. Female host plant preference is strong in several of the populations, supporting the hypothesis that reproductive isolation evolves as an epiphenomenon of host shifts. Differences in wing pigment patterns serve as mate recognition cues used by male butterflies of both morphospecies. High-altitude populations are further distinguished by the strange lack of oviposition adhesive, which appears to be an adaptation to the senescence characteristics of the host plant.

Current work includes the heritability of host plant preference, oviposition cues, and the relative importance of geography and local ecology that maintains geographic variation in the morphology and behavior of this group. We are integrating traditional lab and experimental methods with next generation sequencing technology to further understand the processes responsible for patterns of variation.

Read on....( Forister et al. 2009; Lucas et al. 2008; Gompert et al. 2008; Gompert et al. 2008; Gompert et al. 2006; Gompert et al. 2006; Forister et al. 2006; Fordyce & Nice 2003; Nice et al. 2002; Fordyce et al. 2002; Agrawal & Fordyce 2001)

 

 

 

Direct and indirect interactions among herbivores

Plants are not passive participants in their interactions with their herbivores. Rather, we now know that plants respond dynamically to herbivore damage (induced responses). One area of interest is whether plants respond differently to different herbivores of different feeding guilds. We are examining how plants mediate interactions between conspecific and heterospecific herbivores which may be spatially or phenologically separated. This work includes field experimentation and analysis of quantitative and qualitative changes in host plant secondary chemistry in response to herbivore damage.

Read on ... (Fordyce & Nice 2008; Fordyce 2006; Fordyce 2003; Fordyce & Agrawal 2001; Fordyce 2001; Fordyce & Malcolm 2000)

 

Common members of the milkweed herbivore community

Other ongoing projects and interests...

 

The role of the Sierra Nevada in structuring butterfly populations and facilitating differentiation

Simply put, the Sierra Nevada are pretty darn big mountains. With Matt Forister (UN Reno), Art Shapiro (UC Davis), Chris Nice (Texas State University) and Zach Gompert (UW), we have been conducting a comparative phylogeographic study of various butterfly taxa looking for congruence (or the lack thereof) in patterns of population structure and morphology with an emphasis on the role of the Sierra Nevada as a geographical barrier to gene flow.

Read on: (Fordyce et al. 2008; Fordyce & Nice 2003; Nice et al. 2002; Forister et al. 2004; Gompert et al. 2006; Shapiro et al. 2007)

 

Evolution and ecology of toad toxins (bufodienolides)

The bufodienolide defenses of toads are chemically similar to the cardenolide defenses of milkweeds. With Mike Benard (UC Davis), we have examined the plasticity of these toxins in toads in response to predators. We are currently looking at geographic and phylogenetic patterns of variation in these toxins in collaboration with Greg Pauly (UC Davis) and examining plasticity in bufodianolides across various species of Bufo with Rick Relyea's lab (U. Pitt.).

Read on ... (Benard & Fordyce 2003)

 

 

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