Yale Peabody Museum Summer Internships

Exploring species boundaries within the Viburnum nudum complex

Advisor: Patrick Sweeney with Prof. Michael Donoghue

patrick.sweeney@yale.edu

Length: 6 weeks in the summer

 

Project Description:

Species complexes are groups of closely related species that are similar in appearance and difficult to tell apart. Individuals of the Viburnum nudum complex are deciduous shrubs or small trees with white flowers that bloom in May or June and fleshy fruits that ripen in late summer. The complex occurs throughout eastern North America, and within the complex there are many variable traits involving leaves, inflorescence stalks, fruits, and seeds. The most recent (1983) thorough study recognized just two varieties in the complex: V. nudum var. nudum, distinguished by long inflorescence stalks, lustrous leaves, smooth leaf margins, and raised leaf veins and occurring throughout the southeastern U.S., extending along the coast as far north as Connecticut, and V. nudum var. cassinoides, characterized by shorter inflorescence stalks, dull leaves, wavy leaf margins, and indistinct leaf veins and occurring in all northern portions of the range and at high elevations in the Appalachians with a few populations as far south as central Georgia.

 

Between 2013 and 2016, the Peabody Division of Botany and the Donoghue Lab collected 133 individuals of V. nudum from across its geographic range. Initial Restriction site Associated DNA (RAD) sequencing of 50 individuals discovered genetic evidence at odds with the traditional species delimitation. Instead of finding northern and southern groups within the complex, we instead found three distinct groups. Two separate lineages appear to co-occur in the southeastern U.S., and one is more closely related to the northern populations. We are currently in the process of DNA sequencing 24 additional specimens collected in Georgia, where the two southern lineages co-occur. We hypothesize that there are two different species in the V. nudum complex that co-occur across much of the southeastern U.S. Previous taxonomic treatments have not accurately differentiated these, and it is not clear which morphological characters best separate them.

 

This is primarily a collections-based internship, where an interested undergraduate student would measure multiple morphological traits on museum specimens at the Peabody, in nearby herbaria, and online (for example, leaf size/shape, inflorescence stalk length, petiole length, and leaf margin) that vary across the lineages/geographic range of the V. nudum complex. The student would then build a geographic database of these traits that would be integrated with our molecular data and included in a publication later in the summer.

 

Budget:

Stipend for lodging, food, etc.

$1875

Travel to nearby herbaria will be covered

 
TOTAL$1875

 

CLICK HERE to apply!