Skulls & Scatterplots: Students Analyze Sloth Body Size Variation in the Bocas Del Toro Island Region

Abstract

In this unit, students explore the phylogeography of three-toed sloths (Bradypus pygmaeus and Bradypus variegatus) endemic to the Bocas del Toro islands off the Caribbean coast of Panama. After learning about the geologic history of this region, students measure model sloth skulls from each of the islands and compile that data into scatterplots. Students then analyze the scatterplots to make conclusions about which geographic factors best account for the regional variance in sloth body size. The sequence of activities was designed for high school life science classrooms using the Next Generation Science Standards (NGSS) framework and teaches the disciplinary core idea LS3.B Variation of Traits. This lesson was taught in an integrated co-teaching classroom, a special education classroom, and a ninth-grade general biology classroom. Students successfully answered the overarching research question and gained a deeper knowledge about natural selection and evolution in the process.

Keywords:

• Phylogeography
• project-based learning
• NGSS

Disclosure statement

No potential conflict of interest was reported by the authors.

Online Connections

• Video of sloths on the island of Escudo de Veraguas: https://www.youtube.com/watch?v=DpV4k3Edr-I

• At the time of writing, replica 3-toed sloth skulls (made from polyurethane resin) are available for purchase at the following site: https://www.dinosaurcorporation.com

• Information from Evolutionarily Distinct and Globally Endangered (EDGE) about the Pygmy Three-Toed Sloth status as a critically endangered species: http://www.edgeofexistence.org/species/pygmy-three-toed-sloth/#overview

• An extension for presenting students with information about sloth evolution in other environments: https://slothconservation.org/sloth-genetics-twist/

• Website for calculating correlation coefficients: https://www.socscistatistics.com/tests/pearson/default2.aspx

SUPPLEMENTARY MATERIAL

Supplemental data for this article can be accessed online https://doi.org/10.1080/00368555.2024.2356516

Additional information

Notes on contributors

Kristen Conklin-Kearney

Kristen Conklin-Kearney teaches 8th-12th graders in Long Beach Public Schools and Tyler St. Clair ([email protected]) is an associate professor in the department of chemistry and physics at Longwood University in Virginia. Both authors have published and presented numerous works related to project-based science.