Abstract Detail

Development and Structure

Littell, Charis [1], Krosnick, Shawn [1].

Anatomical diversity of butterfly egg mimic structures in passionflowers (Passiflora L.).

The genus Passiflora (Passifloraceae), also known as passionflowers, is comprised of ca. 550 species distributed in tropical and subtropical regions throughout Mexico, Central and South America, as well as Australasia and the Pacific. The genus is well known for its morphological diversity and charismatic plant-animal interactions. One of the best-known examples of these interactions is that of approximately 100 species of nymphalid butterflies in tribe Heliconiini, known as the passion-vine butterflies. The largest genus in the tribe, Heliconius, has been studied extensively for their use of Passiflora as larval food plants. Larry Gilbert and others have shown that gravid Heliconius butterflies visually search for Passiflora to lay their eggs on. Interestingly, several species of Passiflora possess structures that seem to “mimic” butterfly eggs. Butterflies appear to avoid laying eggs on plants with mimics, possibly to avoid what they perceive as competition for their own eggs. These mimics may then reduce herbivory by deceit. Caterpillars feeding on Passiflora can cause irreversible damage to the plant by stripping leaf tissue and eliminating the potential for reproduction. Egg mimics are varied in form and position and appear to have evolved sporadically across the genus. Not all Passiflora species used as larval food plants possess egg mimics. For example, fritillaries in tribes Argynnini (Speyeria cybele) and Heliconiini (Dione vanillae) lay eggs on Passiflora that lack mimics.
To better understand egg mimic structures in Passiflora, we completed a survey of species known to exhibit mimic-type structures. In some species sampled mimic function was already documented while in others it has been hypothesized but not tested empirically. The present study compares the anatomy of putative mimic structures in 16 species of Passiflora. Tissues were paraffin embedded, sectioned, and stained using Sharman’s staining series to differentiate among cells and tissues, with particular attention to secretory tissues that might produce nectar. Preliminary results suggest that at least five classes of egg mimics exist in Passiflora. These include: 1) aborted floral buds; 2) extension/modification of leaf or leaflet apex; 3) elongation of stipule apex; 4) petiolar nectary; and 5) abaxial leaf nectary. The anatomical details of each mimic class will fully characterized based on the species sampled. These structures will be considered within a phylogenetic context to explore how many times each class has evolved. Finally, a survey of available ecological evidence to support or refute these structures as egg mimics will be provided.

1 - Tennessee Technological University, Department of Biology, Department of Biology, Tennessee Technological University, 1100 N Dixie Ave, Cookeville, TN, 38505, USA

egg mimics

Presentation Type: Poster
Number: P1DS014
Abstract ID:552
Candidate for Awards:Developmental and Structural Section best poster

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