Project title

Feeding Trait Plasticity and Adaptation in Reef Fishes Across the Isthmus of Panama

Mentor name

Dr. Matthieu Leray, STRI Staff,
leraym@si.edu, leray.upmc@gmail.com
Co-mentor: Natasha Hinojosa, STRI Fellow,
nahinojo@ucsc.edu

Location

Naos Laboratories

Project summary and objectives

Reef fishes occupy many trophic niches with diverse feeding morphologies that contribute to maintaining the stability and resiliency of coral reef ecosystems. Despite their critical functional roles, how reef fishes cope with environmental changes remains largely overlooked. Recent research suggests that coral reef fishes can adjust their diet over the short term is response to changes in prey availability (i.e. dietary flexibility). Studies in freshwater fish (cichlids) showed that rapid (diet-induced) adaptive phenotypic plasticity allow organisms to quickly adapt to changes in local environmental conditions.  Yet, we know little about how these evolutionary mechanisms play out in reef fish in different trophic groups and across life stages.

This project leverages the unique geological history of the Panamanian Isthmus and its oceanographically dynamic Pacific coast as a natural experiment to study the plasticity and adaptation of the feeding traits of individual fish with shared ancestors. Present-day coral reef fishes with shared ancestors (i.e., sister species and sister clades) have been physically separated by the Isthmus of Panama for at least 2.8 million years. They have followed separate evolutionary trajectories in their respective habitat range with the distinct environmental conditions of the productive Tropical Eastern Pacific (TEP) and the oligotrophic Caribbean. In the TEP, fishes in the Gulf of Panama experience some of the most drastic annual fluctuations in temperature and nutrients due to intense seasonal upwelling. Conversely, fishes in the nearby Gulf of Chiriquí experience weak to no upwelling due to trade winds being largely blocked by the Cordillera Central mountain range. On the other hand, the Caribbean maintains a stable temperature, and since the closure of the Isthmus, the Caribbean’s primary source of nutrients transferred to the benthos.

Our objectives are:

• Characterize the dynamics of consumer-resource interactions on coral reefs of the TEP and Caribbean of Panama.
• Determine convergent patterns of morphological change between reef fishes across the Isthmus
• Explore the roles of biogeographic isolation and environmental change on the plasticity and adaptation of feeding traits in coral reef fishes

We addressed these objectives by conducting seasonal sampling across regions and oceans to compare responses in gut length, diet, and morphological modifications in the head and jaw. We will analyze oral jaw morphology through a clearing and staining process referred to as ‘diaphanization’ to look at jaw bone placement in situ. We are also conducting visual stomach content analyses along with DNA metabarcoding to determine the diet. This research will ultimately shed light on how exposure to different environmental conditions can influence how reef fish respond to ongoing changes. It will also highlight the importance to study trait adaptation of organisms in geographic areas with high levels of environmental variability.

As of Summer 2024, the field portions for this project have culminated, and the remaining work is focused on processing samples and analyzing data. If you wish to work in this project, we encourage applicants to contact and schedule a meeting with us. Prior to our meeting, please share with us your CV.

Mentorship goals

Interns will have the opportunity to gain experience with morphological dissections and data analysis. Research components include: 1) various types of dissections, 2) visual stomach content analysis and DNA metabarcoding sequencing, 3) morphology photography and digital measurements, 4) preparation of specimens for diaphanization, 5) scientific illustrations for dissection guides. Interns will also participate in data entry and statistical analyses.

Interns will also be given the opportunity to improve their scientific reading and writing skills. They will learn fundamental concepts in the field, learn the scientific process, and practice scientific communication.

Intern’s role, desired background time commitment (appointment period is 3 months) and expected products

We expect the intern to be available full time. The intern should be prepared to spend long days in the field and in the lab during the field season. Expected products include reports, publications, and posters that the intern will be part of.

Statement on diversity, equity, and inclusion: Members of the team aim to foster an inclusive, supportive, and collaborative environment. We believe and acknowledge that our scientific community is enriched and strengthened by diverse perspectives and identities including, but not limited to, ethnicity and national origin, gender and gender identity, class, religion, sexuality, and ability. We are committed to increasing representation of those populations that have been historically excluded from scientific communities and encourage members of marginalized groups to contact us.

What are the regularly held occasions for group discussions, attendance at lectures, career counseling, and other educational and experiential opportunities for your interns?

Interns will be required to participate in bi-weekly lab meetings and weekly STRI seminar Tupper-talks. Lab meetings will include occasional workshops (such as R-workshops, scientific communication, photography, statistical modeling, scientific illustrations, and more). Interns will have weekly one-on-one meetings with their advisor.

List of suggested readings

Wainwright, P. C., Bellwood, D. R., & Sale, P. F. (2002). Ecomorphology of Feeding in Coral reef fishes. Coral reef fishes: dynamics and diversity in a complex ecosystem, 33-55.

Zandonà, E., Auer, S. K., Kilham, S. S., & Reznick, D. N. (2015). Contrasting population and diet influences on gut length of an omnivorous tropical fish, the Trinidadian guppy (Poecilia reticulata). PLoS One, 10(9), e0136079.

Westneat, M. W. (2005). Skull biomechanics and suction feeding in fishes. Fish physiology, 23, 29-75.

Baliga, V. B., & Mehta, R. S. (2014). Scaling patterns inform ontogenetic transitions away from cleaning in Thalassoma wrasses. Journal of Experimental Biology, 217(20), 3597-3606.

Boecklen, W. J., Yarnes, C. T., Cook, B. A., & James, A. C. (2011). On the use of stable isotopes in trophic ecology. Annual Review of Ecology, Evolution and Systematics, 42(1), 411-440.

Muschick, M., Barluenga, M., Salzburger, W., & Meyer, A. (2011). Adaptive phenotypic plasticity in the Midas cichlid fish pharyngeal jaw and its relevance in adaptive radiation. BMC Evolutionary Biology, 11(1), 1-12.