Small-scale phenotypic differentiation along complex stream gradients in a non-native amphipod
- Background: Selective landscapes in rivers are made up by an array of selective forces that vary from source to downstream regions or between seasons, and local/temporal variation in fitness maxima can result in gradual spatio-temporal variation of phenotypic traits. This study aimed at establishing freshwater amphipods as future model organisms to study adaptive phenotypic diversification (evolutionary divergence and/or adaptive plasticity) along stream gradients. Methods: We collected Gammarus roeselii from 16 sampling sites in the Rhine catchment during two consecutive seasons (summer and winter). Altogether, we dissected n = 1648 individuals and quantified key parameters related to morphological and life-history diversification, including naturally selected (e.g., gill surface areas) as well as primarily sexually selected traits (e.g., male antennae). Acknowledging the complexity of selective regimes in streams and the interrelated nature of selection factors, we assessed several abiotic (e.g., temperature, flow velocity) and biotic ecological parameters (e.g., conspecific densities, sex ratios) and condensed them into four principal components (PCs). Results: Generalized least squares models revealed pronounced phenotypic differentiation in most of the traits investigated herein, and components of the stream gradient (PCs) explained parts of the observed differences. Depending on the trait under investigation, phenotypic differentiation could be ascribed to variation in abiotic conditions, anthropogenic disturbance (influx of thermally polluted water), or population parameters. For example, female fecundity showed altitudinal variation and decreased with increasing conspecific densities, while sexual dimorphism in the length of male antennae—used for mate finding and assessment—increased with increasing population densities and towards female-biased sex ratios. Conclusions: We provide a comprehensive protocol for comparative analyses of intraspecific variation in life history traits in amphipods. Whether the observed phenotypic differentiation over small geographical distances reflects evolutionary divergence or plasticity (or both) remains to be investigated in future studies. Independent of the mechanisms involved, variation in several traits is likely to have consequences for ecosystem functions. For example, leaf-shredding in G. roeselii strongly depends on body size, which varied in dependence of several ecological parameters.
Author: | Jonas JourdanORCiDGND, Kathrin Piro, Alexander WeigandORCiDGND, Martin PlathORCiDGND |
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URN: | urn:nbn:de:hebis:30:3-518794 |
DOI: | https://doi.org/10.1186/s12983-019-0327-8 |
ISSN: | 1742-9994 |
Pubmed Id: | https://pubmed.ncbi.nlm.nih.gov/31338113 |
Parent Title (English): | Frontiers in zoology |
Publisher: | BioMed Central |
Place of publication: | London |
Document Type: | Article |
Language: | English |
Year of Completion: | 2019 |
Date of first Publication: | 2019/07/11 |
Publishing Institution: | Universitätsbibliothek Johann Christian Senckenberg |
Release Date: | 2019/12/16 |
Tag: | Aquatic invertebrates; Gammarus roeselii; Global warming; Intraspecific divergence; Invasive species; Life-history evolution; Local adaptation; Rapid evolution; Thermal pollution |
Volume: | 16 |
Issue: | Art. 29 |
Page Number: | 20 |
First Page: | 1 |
Last Page: | 20 |
Note: | Open Access: This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. |
HeBIS-PPN: | 457694793 |
Institutes: | Angeschlossene und kooperierende Institutionen / Senckenbergische Naturforschende Gesellschaft |
Biowissenschaften / Institut für Ökologie, Evolution und Diversität | |
Dewey Decimal Classification: | 5 Naturwissenschaften und Mathematik / 59 Tiere (Zoologie) / 590 Tiere (Zoologie) |
Sammlungen: | Universitätspublikationen |
Open-Access-Publikationsfonds: | Biowissenschaften |
Licence (German): | Creative Commons - Namensnennung 4.0 |