Abstract Detail

Evolutionary Developmental Biology (Evo-Devo)

Burrus, Abagail [1], Kramer, Elena [2].

Understanding Gland Development and Evolution in the Malpighiaceae.

The Malpighiaceae are a family of pantropical flowering plants that are presumed to have co-evolved originally with South American oil bees and offer oil rewards rather than more traditional pollen or nectar alone. These oil rewards are produced in highly specialized glandular tissue borne on the calyx of Malpighiaceae flowers. While studies to date observe neotropical floral conservation in this family, this is based on analyses of broad morphological observations in the family, such as floral symmetry, gland number, or gland arrangement on the calyx. Likewise, the historical assumption that Malpighiaceae oil glands are homologous to extrafloral nectaries has been based on limited evidence: mature tissue in very few neotropical species showing many anatomical similarities. Oil glands are found in ten other families as well (both dicot and monocot), but they are most prevalent in their oldest family of occurrence, the Malpighiaceae- making this system ideal for examining the nature of this morphological feature. Malpighiaceae outside the neotropics also promise fascinating stories of ways the oil glands have changed with the loss of oil bee mutualists: glands disappear, become rudimentary, or even produce nectar instead.
This talk focuses on the beginning of dissertation work that tests the assumptions of conservatism and gland homology with more comprehensive sampling and a much more thorough incorporation of biological evidence. Broad patterns in oil gland (and extrafloral nectary) evolution are explored with ancestral trait reconstructions, questioning the origin of the oil glands and helping select candidate taxa for developmental studies. Histochemical tests will be performed on these floral and extrafloral glands to better define the differences between 'oil glands' and 'extrafloral nectaries' and resolve contradicting literature describing their exudates. Developmental series are produced for various neotropical and paleotropical representatives, uncovering much earlier gland initiation than previously thought, detailing the growth of these features previously only examined at maturity, and establishing comparative stages of development. Developmental series are performed for both floral and extrafloral glands in representative taxa. The developmental staging of these glands will also inform sampling of early and late glandular tissue for a series of RNA-Seq experiments that will acquire an even deeper look at the question of similarity between various glands. Data presented in this talk are primarily focused on the reconstructions and developmental and histological series, but part of the motivation behind this talk is to also share exciting possible results.

1 - Harvard University, Organismic and Evolutionary Biology, 16 Divinity Avenue, Cambridge, Massachusetts, 02138, United States
2 - Harvard Univ., OEB, 16 Divinity Ave, Cambridge, MA, 02138, United States

Keywords:
oil glands
Malpighiaceae
trait evolution
Developmental morphology
plant trait.

Presentation Type: Oral Paper
Session: EVDV1, Evolutionary Developmental Biology (Evo-Devo)
Location: Tucson E/Starr Pass
Date: Monday, July 29th, 2019
Time: 5:15 PM
Number: EVDV1015
Abstract ID:538
Candidate for Awards:Katherine Esau Award