Phenotypic differentiation in a heterogeneous environment: morphological and life‐history responses to ecological gradients in a livebearing fish. (13th August 2019)

• Record Type: Journal Article
• Authors: Santi, F.; Petry, A. C.; Plath, M.; Riesch, R.
• Is Part Of: Journal of zoology. Volume 310:Number 1(2020)
• Page Start: 10
• Page End: 23
• Publication Date: 2019-08-13
• Subjects: body shape -- environmental gradients -- Phalloptychus januarius -- Poeciliidae -- predictable evolution -- phenotypic differentiation -- life‐history traits; Zoology -- Periodicals; Zoologie -- Périodiques; 590.5
• DOI: 10.1111/jzo.12720
• Languages: English
• ISSNs: 0952-8369

Abstract

Abstract: Predicting how environmental variation drives phenotypic diversification is one of the main aims of evolutionary ecology. Yet, we still only have a limited understanding of how it drives diversity, especially when multiple factors interact. To address this issue, the superfetating livebearing fish Phalloptychus januarius (Poeciliidae) was repeatedly sampled (over a 2‐year period) in four coastal lagoons in Brazil to investigate the relative contribution of different environmental factors on phenotypic patterns. We further compare our results to those reported for another poeciliid ( Poecilia vivipara ), which inhabits some of the same lagoons but has a drastically different reproductive strategy (no superfetation). We used a model‐averaging approach to estimate the relative importance of differences in predation pressure, salinity, dissolved oxygen, pH, temperature and food availability in driving variation in body shape, life histories, and life‐history proxies. We found consistent population differences in several traits, but also seasonal variation within each lagoon. Specifically, predation, oxygen availability and pH affected several different traits and played important roles in driving phenotypic differences between and amongst populations. Moreover, our study reveals differential responses in phenotypic traits to the same environmental gradients between P. januarius (this study) and P. vivipara (previous studies), and we suggest that future work should further investigate differential phenotypic responses to single versus multiple concomitant selective forces, and how this affects different species. Abstract : Our ability to predict how environmental variation drives phenotypic diversification is still limited when multiple environmental factors interact. We investigated body‐shape and life‐history variation in the fish Phalloptychus januarius (Poeciliidae) from coastal lagoons in Brazil with starkly different ecological conditions. We found consistent population differences and seasonal variation within each lagoon in several traits. Specifically, predation, oxygen availability, and pH played important roles in driving phenotypic differences between and among populations. However, many of these effects were often contrary to what we predicted a priori. We suggest that this can be explained by the presence of multifarious selection, as certain effects can add up, while others can cancel each other out, leading to unpredictable patterns. Our results therefore stress the importance of multivariate approaches in this type of studies.