Phenotypically plastic responses to predation threat in the mangrove rivulus fish (Kryptolebias marmoratus): behavior and morphology
Early life environments have important effects on phenotype development, but it can be difficult to disentangle the relative influences of genotype and environment on phenotypic variation within and among populations. Mangrove rivulus fish (Kryptolebias marmoratus) reproduce by self-fertilization and can generate isogenic lineages, which provides opportunities to resolve how the environment shapes the phenotype independent of genetic variation. Rivulus’ ecology is not well understood, but mangrove water snakes (Nerodia clarkii compressicauda) are thought to be a major predator. To test developmental responses to predator-related cues, four rivulus lineages (two that naturally co-exist with snakes; two that do not) were exposed to one of three treatments for 30 days post-hatching: cues from snakes that were fasted, fed rivulus, or fed heterospecifics. One week after exposure, fear and boldness responses were quantified. Individuals were photographed at 2 and 6 months of age for body size, growth, and body shape analysis. Animals that have historically encountered snakes were more risk averse and had wider heads than animals that historically have not encountered snakes. Rivulus exposed to cues from snakes fed conspecifics or heterospecifics grew faster than those exposed to fasted snake cues. Body shape was more streamlined in animals exposed to cues from snakes fed conspecifics, which may facilitate increased jumping performance as a way to escape aquatic predators. Our results suggest that rivulus exhibit phenotypic plasticity in response to cues associated with predator threat and that historical effects from selection or other evolutionary processes also are important determinants of behavioral and morphological variation.
KeywordsPhenotypic plasticity Mangrove rivulus Predation Kryptolebias marmoratus
This study was performed in accordance with the University of Alabama Institutional Animal Care and Use Committee (Protocol #’s 08-312 [13-10-0048] and [14-05-0071]). The authors would like to thank D. Scott Taylor, Yvonne Wielhouwer, Mark Garcia, Benjamin Perlman, and the staff at the Keys Marine Laboratory for assistance in field collections and logistics, Matthew Symonds for his patience during the revision process, and two reviewers for very insightful comments that significantly improved the manuscript.
Compliance with ethical standards
Conflict of interest
The authors declare no conflicts of interest.
- Bookstein FL (1997) Morphometric tools for landmark data: geometry and biology. Cambridge University Press, CambridgeGoogle Scholar
- Chivers DP, Wisenden BD, Hindman CJ, Michalak TA, Kusch RC, Kaminskyj SG, Jack KL, Ferrari MC, Pollock RJ, Halbgewachs CF (2007) Epidermal ‘alarm substance’ cells of fishes maintained by non-alarm functions: possible defence against pathogens, parasites and UVB radiation. Proc R Soc Lond B 274:2611–2619CrossRefGoogle Scholar
- Davis WP, Taylor DS, Turner BJ (1990) Field observations of the ecology and habits of mangrove rivulus (Rivulus marmoratus) in Belize and Florida (Teleostei: Cyprinodontiformes: Rivulidae). Ichthyol Explor Freshw 1:123–134Google Scholar
- R Core Team (2012) R: a language and environment for statistical computing. R Foundation for Statistical Computing, Vienna. ISBN 3-900051-07-0Google Scholar
- Rohlf F (2010) tpsDig, version 2.16. Department of Ecology and Evolution, State University of New York, Stony BrookGoogle Scholar
- West-Eberhard MJ (2003) Developmental plasticity and evolution. Oxford University Press, OxfordGoogle Scholar
- Zelditch ML, Swiderski DL, Sheets HD (2004) Geometric morphometrics for biologists: a primer. Academic Press, LondonGoogle Scholar