Research
Brown, C.E., and A. Kirk. (In Prep). How salamanders skydive: Characterizing airflow over wandering salamanders (Aneides vagrans) through computational fluid dynamics.
Brown, C.E., E.A. Sathe, R. Dudley, and S.M. Deban. (2022). Aerial maneuvering by plethodontid salamanders across an arboreality gradient. [Manuscript submitted for publication] Journal of Experimental Biology
Brown, C.E., E.A. Sathe, R. Dudley, and S.M. Deban. 2022. Gliding and Parachuting by arboreal salamanders (Genus: Aneides). Current Biology 32(7).
*Aretz, J., C.E. Brown, S.M. Deban. 2021. Vertical locomotion in the arboreal salamander Aneides vagrans. Zoology 316: 72-79. *Undergraduate 1st author
Brown, C.E., J.C. Spickler, S.B. Marks, and H.H. Whiteman. 2022. Efficacy of PIT telemetry in three species of salamander from the western United States: Ensatina eschscholtzii, Aneides vagrans, and Ambystoma tigrinum nebulosum. Herp Con Bio 17(1).
Brown, C.E. 2020. Aneides vagrans – oviposition. Herpetoculture 51(1): 64-65.
Brown, C.E., and S.M. Deban. 2020. Jumping in arboreal salamanders: a possible trade-off between takeoff velocity and in-air posture. Zoology 138(2020): 125724.
Brown, C.E., J.C. Spickler, S.B. Marks, and J.O. Reiss. 2018. Aneides vagrans is absent from angiosperm crowns in an old-growth redwood forest. Herp Con Bio 13(3): 533-538.
My research interests include the movements of amphibians, especially plethodontid salamanders, ranging from fine-scale biomechanics of locomotion to dispersal at the ecosystem level.
Recently, we discovered that arboreal salamanders can parachute and glide. Now, I am interested in exploring the links between genetics, morphology, and aerial abilities in salamanders.
Ultimately, my work examines the life history of amphibians in the broader context of ecological and evolutionary theory with the goal of increasing awareness for conservation.
Model Systems for Amphibian Movement
The crowns of coast redwood trees are home to an impressively biodiverse community. Among the residents of the world's tallest trees: Wandering Salamanders, Aneides vagrans.
Extreme niches feature strong selection and make great focal systems.
High in the Colorado Rockies, where the effects of climate change are accelerated, an isolated population of Arizona tiger salamanders (Ambystoma mavortium nebulosum) exhibits facultative paedomorphosis at the edge of their elevational range.
Range edges are fantastic places to study changes in dispersal due to changes in climate.
Jumping Escape Response in Arboreal Salamanders
wandering salamander jump.mp4The scientific process begins with a simple observation or question. Here, we observe a wandering salamander (Aneides vagrans) leaping from a redwood. What curiosities does this video inspire within you?
AV02_11.movWe then collect data to investigate these curiosities closer, often testing against a specific hypothesis. Can you hypothesize how a salamander jumps?
Brown & Deban (2020), Zoology
It turns out that arboreal salamanders jump with two feet from vertical surfaces more often than other salamanders, and their takeoff velocity is notably slower. Importantly, they also assume skydiving postures more quickly after jumping.
The beauty of science is that each inquiry leads to a multitude of new observations and questions. The scientific process, in this sense, is really more of a scientific cycle. Do you have a hypothesis regarding why wandering salamanders, which live in the tallest trees on Earth, might use skydiving postures?
Gliding, Parachuting, and Maneuvering in Arboreal Salamanders
I am currently studying the air-righting, parachuting, gliding, and maneuvering of plethodontid salamanders using vertical wind tunnel experiments and field tests. These experiments reveal the mechanisms by which salamanders direct their falls, which inform ecomorphological evolution and lend to conservation. These gliding salamanders captivate and inspire, attributes that can be used to promote redwood conservation and restoration.
AirrightingParachute_Trim_B.mp4Aneides vagrans executes a crisp air-righting maneuver via a tail rotation, and immediately assumes a parachute posture. Wind speeds are held constant, so the change in vertical direction indicates a change in vertical velocity (i.e. a parachute).
SalTurn.mp4Aneides lugubris makes a sharp banking turn, initiated by the adduction of the right hindfoot and maintained with a parachute posture. Banking turns could help the animals remain in their arboreal habitats after a fall or jump by guiding them to the trunk or lower branches.
Dispersal and Distribution of Alpine Tiger Salamanders
Anthropogenic climate change is accelerated at high altitudes, and is already drastically affecting hydroperiods and temperatures of subalpine ponds in the Rocky Mountains. How will these changes impact amphibians at the edge of their elevational range? Specifically, I am interested in changes to annual migration patterns of metamorphic Arizona tiger salamanders and within-pond distribution of paedomorhps and larvae. This research will help us predict and understand the future distribution of amphibians at range edges with major implications for competition, disease ecology, and more.
By uniquely marking the tiger salamanders with Passive Integrated Transponder (PIT) tags, a slightly smaller version of your dog's 'microchip', we are able to remotely detect their locations and movements. Amphibians are not always surface-active and thus can be hard to find by visual cues alone, but the PIT tag transmissions can be detected through soil, water, and vegetation. Handheld antennae and wands are used to scan the warm, shallow pools called thermal zones that these high alpine ectotherms rely on for thermoregulation.
GIS maps of observed tiger salamander locations suggest a clumped distribution within ponds. This dense clustering has implications for intraspecific competition, cannibalistic size-structure dynamics, and disease outbreak. Interestingly, we have learned that this remote detection method is capable of finding tagged animals that have evaded capture by researchers for over a decade! The improved accuracy and enhanced scale of our mark-recapture data as a result of PIT telemetry will be critical to understanding how changing temperatures and hydroperiods will influence the ecology and evolution of these environmental sentinels.
