1
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Sawecki J, Dijkstra PD. Mothers modify the cost of reproduction by dynamic changes in antioxidant function and filial cannibalism. Biol Lett 2022; 18:20220319. [PMID: 36349581 PMCID: PMC9653243 DOI: 10.1098/rsbl.2022.0319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 10/10/2022] [Indexed: 11/11/2023] Open
Abstract
Investment in current reproduction may negatively influence subsequent fitness. Oxidative stress has been proposed as a potential mediator of this trade-off between current and future reproductive success. However, evidence of reproduction causing oxidative stress is limited, possibly owing to compensatory mechanisms that counteract oxidative insults. Here we test the idea that organisms protect against oxidative challenges through a dynamic interaction between behavioural and physiological adjustments at different stages of reproduction. To test this idea, we manipulated maternal care in the mouthbrooding cichlid fish Astatotilapia burtoni by allowing females to continue care (brooders) or by preventing care (non-brooders). We found that brooders depleted the pool of antioxidants as brood care progressed; however, we only observed increased oxidative DNA damage at the early stage of care relative to non-brooders, possibly owing to upregulated antioxidant protection during later stages of care. Most brooders adjusted parental investment by consuming some of their offspring during mouthbrooding. Intriguingly, the level of filial cannibalism was positively related to liver antioxidant function. These changes in antioxidant function and filial cannibalism allow parents to manage the cost of reproduction and are important for our understanding of how oxidative stress mediates life-history trade-offs.
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Affiliation(s)
- Jake Sawecki
- Department of Biology, Central Michigan University, Mount Pleasant, MI 48859, USA
| | - Peter D. Dijkstra
- Department of Biology, Central Michigan University, Mount Pleasant, MI 48859, USA
- Neuroscience Program, Central Michigan University, Mount Pleasant, MI 48859, USA
- Institute for Great Lakes Research, Central Michigan University, Mount Pleasant, MI 48859, USA
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2
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Abecia JE, Luiz OJ, Crook DA, Banks SC, Wedd D, King AJ. Sex and male breeding state predict intraspecific trait variation in mouth-brooding fishes. JOURNAL OF FISH BIOLOGY 2022; 101:550-559. [PMID: 35638470 PMCID: PMC9544576 DOI: 10.1111/jfb.15122] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 05/25/2022] [Indexed: 06/15/2023]
Abstract
Sex-specific reproductive roles contribute to sexual dimorphic morphological trait variations. In uniparental mouth-brooding fishes, the mouth performs a reproductive function in addition to its key roles in feeding and respiration, resulting in the potential for sex-specific functional performance trade-offs. Trait differences related to parental care may occur when the individual matures or be restricted to periods when the parent is mouth-brooding. This study explored sexual dimorphism and morphological trait adaptations related to feeding, breeding, respiration and locomotion performance in two paternal mouth-brooding freshwater fishes (Glossamia aprion and Neoarius graeffei). Eight morphological traits were evaluated for sexual dimorphism (non-brooder males vs. females) and male breeding state differences (brooders vs. non-brooders). Male breeding state was a significant predictor of trait variation in both species. Brooders differed in buccal volume and in several feeding and locomotory traits compared to non-brooder males. Non-brooder males had bigger buccal volumes and relative eye diameters (G. aprion) and larger relative gape sizes (N. graeffei) compared to females, a potential response to both mouth-brooding and feeding requirements. Although there were clear trait differences between brooder and non-brooder males, further research is required to confirm whether individuals return to their former morphology once mouth-brooding has ceased or if trait differences are maintained post-brooding. This study highlights the importance of considering the potential impacts of intraspecific trait variation on the performance of critical life functions, such as feeding, respiration and locomotion across the life history.
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Affiliation(s)
- Janine E. Abecia
- Research Institute for the Environment and LivelihoodsCharles Darwin UniversityCasuarinaNorthern TerritoryAustralia
| | - Osmar J. Luiz
- Research Institute for the Environment and LivelihoodsCharles Darwin UniversityCasuarinaNorthern TerritoryAustralia
| | - David A. Crook
- Research Institute for the Environment and LivelihoodsCharles Darwin UniversityCasuarinaNorthern TerritoryAustralia
- Centre for Freshwater EcosystemsLa Trobe UniversityAlburyVictoriaAustralia
| | - Sam C. Banks
- Research Institute for the Environment and LivelihoodsCharles Darwin UniversityCasuarinaNorthern TerritoryAustralia
| | - Dion Wedd
- Research Institute for the Environment and LivelihoodsCharles Darwin UniversityCasuarinaNorthern TerritoryAustralia
| | - Alison J. King
- Research Institute for the Environment and LivelihoodsCharles Darwin UniversityCasuarinaNorthern TerritoryAustralia
- Centre for Freshwater EcosystemsLa Trobe UniversityAlburyVictoriaAustralia
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3
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Weller H, López-Fernández H, McMahan CD, Brainerd EL. Relaxed feeding constraints facilitate the evolution of mouthbrooding in Neotropical cichlids. Am Nat 2022; 199:E197-E210. [DOI: 10.1086/719235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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4
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Naughton LF, Kruppert S, Jackson B, Porter ME, Donatelli CM. A Tail of Four Fishes: An Analysis of Kinematics and Material Properties of Elongate Fishes. Integr Comp Biol 2021; 61:603-612. [PMID: 33956151 DOI: 10.1093/icb/icab060] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The elongate body plan is present in many groups of fishes, and this morphology dictates functional consequences seen in swimming behavior. Previous work has shown that increasing the number of vertebrae, or decreasing the intervertebral joint length, in a fixed length artificial system increases stiffness. Tails with increased stiffness can generate more power from tail beats, resulting in an increased mean swimming speed. This demonstrates the impacts of morphology on both material properties and kinematics, establishing mechanisms for form contributing to function. Here, we wanted to investigate relationships between form and ecological function, such as differences in dietary strategies and habitat preferences among fish species. This study aims to characterize and compare the kinematics, material properties, and vertebral morphology of four species of elongate fishes: Anoplarchus insignis, Anoplarchus purpurescens, Xiphister atropurpureus, and Xiphister mucosus. We hypothesized that these properties would differ among the four species due to their differential ecological niches. To calculate kinematic variables, we filmed these fishes swimming volitionally. We also measured body stiffness by bending the abdominal and tail regions of sacrificed individuals in different stages of dissection (whole body, removed skin, and removed muscle). Finally, we counted the number of vertebrae from CT scans of each species to quantify vertebral morphology. Principal component and linear discriminant analyses suggested that the elongate fish species can be distinguished from one another by their material properties, morphology, and swimming kinematics. With this information combined, we can draw connections between the physical properties of the fishes and their ecological niches.
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Affiliation(s)
- Lydia F Naughton
- Department of Biology, Bucknell University, 701 Moore Avenue, Lewisburg, PA 17837, USA
| | - Sebastian Kruppert
- Department of Biology, Friday Harbor Labs, University of Washington, 620 University Road, Friday Harbor, WA 98250, USA
| | - Beverly Jackson
- Idaho State University, 921 S 8th Avenue, Pocatello, ID 83209, USA
| | - Marianne E Porter
- Department of Biological Sciences, Florida Atlantic University, 777 Glades Road Boca Raton, FL 33431, USA
| | - Cassandra M Donatelli
- Department of Biology, University of Ottawa, Marie-Curie Private, Ottawa, ON, Canada K1N 9A7
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5
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Galeano-Chavarria AM, Landaeta MF, Plaza G, Castillo MI, Alarcón DS. Environmental determinants in morphospace and diet of the larval blenny Calliclinus geniguttatus from an upwelling ecosystem. JOURNAL OF FISH BIOLOGY 2020; 97:1808-1820. [PMID: 32935358 DOI: 10.1111/jfb.14544] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 09/08/2020] [Accepted: 09/13/2020] [Indexed: 06/11/2023]
Abstract
The effects of two contrasting environmental conditions in nearshore waters off central Chile on the diet and morphospace of two cohorts of larval labrisomid blenny Calliclinus geniguttatus were studied using geometric morphometrics and gut content analysis. The two environmental conditions corresponded to (a) a cold period with upwelling-favourable southwesterly winds and a mixed water column of cooler water and (b) a warm period with calm winds and stratified warmer water. During the cold period, fish larvae had a more hydrodynamic head shape, longer jaws and a higher feeding incidence, suggesting a greater food supply due to upwelling events and a possible increase in encounter rates in the turbulent environment. In contrast, the larvae from the warm period had a more robust head shape with smaller jaws and a lower feeding incidence, which was related to higher water temperatures and lower wind intensities. The present study suggests that larvae have a rapid response to environmental changes on a short time scale (i.e., from weeks to months), showing a link between environmental conditions and changes in the phenotypic traits and diet of the larval stages of this cryptobenthic species.
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Affiliation(s)
- Ana María Galeano-Chavarria
- Laboratorio de Ictioplancton (LABITI), Escuela de Biología Marina, Facultad de Ciencias del Mar y de Recursos Naturales, Universidad de Valparaíso, Viña del Mar, Chile
- Programa Magíster en Oceanografía, Universidad de Valparaíso and Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile
- Laboratorio de Esclero-cronología, Escuela de Ciencias del Mar, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile
| | - Mauricio F Landaeta
- Laboratorio de Ictioplancton (LABITI), Escuela de Biología Marina, Facultad de Ciencias del Mar y de Recursos Naturales, Universidad de Valparaíso, Viña del Mar, Chile
- Centro de Observación Marino para Estudios de Riesgos del Ambiente Costero (COSTA-R), Universidad de Valparaíso, Valparaíso, Chile
| | - Guido Plaza
- Laboratorio de Esclero-cronología, Escuela de Ciencias del Mar, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile
| | - Manuel I Castillo
- Centro de Observación Marino para Estudios de Riesgos del Ambiente Costero (COSTA-R), Universidad de Valparaíso, Valparaíso, Chile
- Laboratorio de Oceanografía Física y Satelital (LOFISAT), Facultad de Ciencias del Mar y de Recursos Naturales, Universidad de Valparaíso, Valparaíso, Chile
| | - Darly S Alarcón
- Laboratorio de Oceanografía Física y Satelital (LOFISAT), Facultad de Ciencias del Mar y de Recursos Naturales, Universidad de Valparaíso, Valparaíso, Chile
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6
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De Meyer J, Verhelst P, Adriaens D. Saving the European Eel: How Morphological Research Can Help in Effective Conservation Management. Integr Comp Biol 2020; 60:467-475. [PMID: 32108900 DOI: 10.1093/icb/icaa004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The European eel (Anguilla anguilla) is a critically endangered species, whose recruitment stocks have declined to nearly 1% compared to the late 70s. An amalgam of factors is responsible for this, among them migration barriers, pollution, habitat loss, parasite infection, and overfishing. A lot of recent studies focus on aspects that can increase the mature silver eel escapement rate, such as identifying migration barriers and developing passageways or addressing the impact of pollution on the eel's health. However, little attention is given to the eel's morphology in function of management measures. Worryingly, less than 50% of the currently installed management plans reach their goals, strongly indicating that more information is needed about the eel's ecology and behavior. Functional morphological studies provide insights on how species perform behaviors crucial for survival, such as feeding and locomotion, but also in how environmental changes can affect or limit such behaviors. Consequently, functional morphology represents an important biotic component that should be taken into account when making conservation decisions. Hence, here, we provide an overview of studies on the eel's morphology that do not only demonstrate its relation with ecology and behavior, but also provide information for developing and installing proper and more specific management measures.
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Affiliation(s)
- Jens De Meyer
- Evolutionary Morphology of Vertebrates, Ghent University, K.L. Ledeganckstraat 35, Ghent 9000, Belgium
| | | | - Dominique Adriaens
- Evolutionary Morphology of Vertebrates, Ghent University, K.L. Ledeganckstraat 35, Ghent 9000, Belgium
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7
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Raffini F, Schneider RF, Franchini P, Kautt AF, Meyer A. Diving into divergence: Differentiation in swimming performances, physiology and gene expression between locally‐adapted sympatric cichlid fishes. Mol Ecol 2019; 29:1219-1234. [DOI: 10.1111/mec.15304] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2019] [Revised: 10/24/2019] [Accepted: 11/08/2019] [Indexed: 12/25/2022]
Affiliation(s)
- Francesca Raffini
- Lehrstuhl für Zoologie und Evolutionsbiologie Department of Biology University of Konstanz Konstanz Germany
- International Max Planck Research School (IMPRS) for Organismal Biology Max‐Planck‐Institut für Ornithologie Radolfzell Germany
- Max Planck Institute for Ornithology Radolfzell Germany
| | - Ralf F. Schneider
- Lehrstuhl für Zoologie und Evolutionsbiologie Department of Biology University of Konstanz Konstanz Germany
- International Max Planck Research School (IMPRS) for Organismal Biology Max‐Planck‐Institut für Ornithologie Radolfzell Germany
| | - Paolo Franchini
- Lehrstuhl für Zoologie und Evolutionsbiologie Department of Biology University of Konstanz Konstanz Germany
| | - Andreas F. Kautt
- Lehrstuhl für Zoologie und Evolutionsbiologie Department of Biology University of Konstanz Konstanz Germany
| | - Axel Meyer
- Lehrstuhl für Zoologie und Evolutionsbiologie Department of Biology University of Konstanz Konstanz Germany
- International Max Planck Research School (IMPRS) for Organismal Biology Max‐Planck‐Institut für Ornithologie Radolfzell Germany
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8
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Ronco F, Roesti M, Salzburger W. A functional trade-off between trophic adaptation and parental care predicts sexual dimorphism in cichlid fish. Proc Biol Sci 2019; 286:20191050. [PMID: 31431167 PMCID: PMC6732390 DOI: 10.1098/rspb.2019.1050] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Although sexual dimorphism is widespread in nature, its evolutionary causes often remain elusive. Here we report a case where a sex-specific conflicting functional demand related to parental care, but not to sexual selection, explains sexual dimorphism in a primarily trophic structure, the gill rakers of cichlid fishes. More specifically, we examined gill raker length in a representative set of cichlid fish species from Lake Tanganyika featuring three different parental care strategies: (i) uni-parental mouthbrooding, whereby only one parental sex incubates the eggs in the buccal cavity; (ii) bi-parental mouthbrooding, whereby both parents participate in mouthbrooding; and (iii) nest guarding without any mouthbrooding involved. As predicted from these different parental care strategies, we find sexual dimorphism in gill raker length to be present only in uni-parental mouthbrooders, but not in bi-parental mouthbrooders nor in nest guarders. Moreover, variation in the extent of sexual dimorphism among uni-parental mouthbrooders appears to be related to trophic ecology. Overall, we present a previously unrecognized scenario for the evolution of sexual dimorphism that is not related to sexual selection or initial niche divergence between sexes. Instead, sexual dimorphism in gill raker length in uni-parental mouthbrooding cichlid fish appears to be the consequence of a sex-specific functional trade-off between a trophic function present in both sexes and a reproductive function present only in the brooding sex.
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Affiliation(s)
- Fabrizia Ronco
- Zoological Institute, University of Basel, Vesalgasse 1, 4051 Basel, Switzerland
| | - Marius Roesti
- Zoological Institute, University of Basel, Vesalgasse 1, 4051 Basel, Switzerland.,Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, British Columbia, Canada V6T1Z4.,Institute of Ecology and Evolution, University of Bern, Bern 3012, Switzerland
| | - Walter Salzburger
- Zoological Institute, University of Basel, Vesalgasse 1, 4051 Basel, Switzerland
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9
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Sawecki J, Miros E, Border SE, Dijkstra PD. Reproduction and maternal care increase oxidative stress in a mouthbrooding cichlid fish. Behav Ecol 2019. [DOI: 10.1093/beheco/arz133] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
AbstractInvestment in reproduction and postzygotic parental care is an energetically costly yet fundamental aspect of the life-history strategies in many species. Recently, oxidative stress has received attention as a potential mediator in the trade-off between reproduction, growth, and survival. During activities that increase metabolic activity, such as providing offspring care, an overproduction of reactive oxygen species can occur that cannot be counteracted by antioxidants, leading to oxidative stress and tissue damage. Here, we investigated the oxidative costs of reproduction and maternal care over the course of the reproductive cycle in a mouthbrooding cichlid fish within socially stable and unstable environments. We manipulated social stability by disrupting the habitat in socially unstable tanks. We expected to see an increase in the burden of maternal care within unstable environments due to increased male harassment of females as a byproduct of increased male–male aggression. We found that brooding females have higher levels of oxidative stress than nonbrooding females and oxidative stress fluctuates throughout the reproductive cycle. These fluctuations were driven by a spike in reactive oxygen metabolites at the beginning of brood care followed by an increase in antioxidant defense. Surprisingly, the link between reproduction and oxidative stress was not different between females from stable or unstable environments. Our study illustrates a more complete picture of the physiological costs of reproduction and parental care throughout different stages of care rather than a simplistic end-point observation of how reproduction and parental care affect an individual.
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Affiliation(s)
- Jacob Sawecki
- Department of Biology, Central Michigan University, Mount Pleasant, MI, USA
| | - Emily Miros
- Department of Biology, Central Michigan University, Mount Pleasant, MI, USA
| | - Shana E Border
- Department of Biology, Central Michigan University, Mount Pleasant, MI, USA
| | - Peter D Dijkstra
- Department of Biology, Central Michigan University, Mount Pleasant, MI, USA
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10
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Podgorniak T, Brockmann S, Konstantinidis I, Fernandes JMO. Differences in the fast muscle methylome provide insight into sex-specific epigenetic regulation of growth in Nile tilapia during early stages of domestication. Epigenetics 2019; 14:818-836. [PMID: 31131688 PMCID: PMC6597363 DOI: 10.1080/15592294.2019.1618164] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2018] [Revised: 05/02/2019] [Accepted: 05/04/2019] [Indexed: 01/14/2023] Open
Abstract
Growth is a complex trait whose variability within a population cannot be explained solely by genetic variation. Epigenetic regulation is often suggested as an important factor shaping the phenotype, but its association with growth can be highly context- and species-dependent. Nevertheless, the mechanisms involved in epigenetic regulation of growth in fish are poorly understood. We have used reduced representation bisulphite sequencing to determine the genome-wide CpG methylation patterns in male and female Nile tilapia of different sizes but at the same early stage of domestication. The average CpG methylation level in the reduced genome representation was 63% across groups but many sites displayed group-specific methylation patterns. The number of differentially methylated (DM) CpGs was much higher when the interaction between sex and weight was included rather than when these factors were considered separately. There were 1128 DM CpGs between large and small females and 970 DM CpGs between large and small males. We have found many growth-related genes associated with DM CpGs, namely map3k5 and akt3 in females and gadd45g and ppargc1a in males. Only 5% of CpG locations associated with growth were common to both sexes. In particular, the autophagy-related gene atg14 displayed a high association of methylation with growth exclusively in males. The sexually dimorphic association between atg14 methylation and growth may uncover novel metabolic mechanisms at play during mouth brooding in Nile tilapia females. Taken together, our data suggest that epigenetic regulation of growth in Nile tilapia involves different gene networks in males and females.
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Affiliation(s)
- Tomasz Podgorniak
- Genomics Division, Faculty of Biosciences and Aquaculture, Nord University, Bodø, Norway
| | - Sven Brockmann
- Genomics Division, Faculty of Biosciences and Aquaculture, Nord University, Bodø, Norway
| | - Ioannis Konstantinidis
- Genomics Division, Faculty of Biosciences and Aquaculture, Nord University, Bodø, Norway
| | - Jorge M. O. Fernandes
- Genomics Division, Faculty of Biosciences and Aquaculture, Nord University, Bodø, Norway
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11
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Hulsey CD, Holzman R, Meyer A. Dissecting a potential spandrel of adaptive radiation: Body depth and pectoral fin ecomorphology coevolve in Lake Malawi cichlid fishes. Ecol Evol 2018; 8:11945-11953. [PMID: 30598789 PMCID: PMC6303698 DOI: 10.1002/ece3.4651] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2018] [Revised: 09/22/2018] [Accepted: 10/01/2018] [Indexed: 01/11/2023] Open
Abstract
The evolution of body shape reflects both the ecological factors structuring organismal diversity as well as an organism's underlying anatomy. For instance, body depth in fishes is thought to determine their susceptibility to predators, attractiveness to mates, as well as swimming performance. However, the internal anatomy influencing diversification of body depth has not been extensively examined, and changes in body depth could arise as a by-product of functional changes in other anatomical structures. Using an improved phylogenetic hypothesis for a diverse set of Lake Malawi cichlid fishes, we tested the evolutionary association between body depth and the height of the pectoral girdle. To refine the functional importance of the observed substantial correlation, we also tested the coevolution of pectoral girdle height and pectoral fin area. The extensive coevolution of these traits suggests body depth in fishes like the Lake Malawi cichlids could diverge simply as a by-product of being tightly linked to ecomorphological divergence in other functional morphological structures like the pectoral fins.
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Affiliation(s)
| | - Roi Holzman
- School of Zoology, Faculty of Life scienceTel Aviv University, Tel Aviv, Israel and The Inter‐University Institute for Marine SciencesEilatIsrael
| | - Axel Meyer
- Department of BiologyUniversity of KonstanzKonstanzGermany
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12
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Verhelst P, De Meyer J, Reubens J, Coeck J, Goethals P, Moens T, Mouton A. Unimodal head-width distribution of the European eel ( Anguilla anguilla L.) from the Zeeschelde does not support disruptive selection. PeerJ 2018; 6:e5773. [PMID: 30416881 PMCID: PMC6225841 DOI: 10.7717/peerj.5773] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2018] [Accepted: 09/17/2018] [Indexed: 11/20/2022] Open
Abstract
Since the early 20th century, European eels (Anguilla anguilla L.) have been dichotomously classified into 'narrow' and 'broad' heads. These morphs are mainly considered the result of a differential food choice, with narrow heads feeding primarily on small/soft prey and broad heads on large/hard prey. Yet, such a classification implies that head-width variation follows a bimodal distribution, leading to the assumption of disruptive selection. We investigated the head morphology of 272 eels, caught over three consecutive years (2015-2017) at a single location in the Zeeschelde (Belgium). Based on our results, BIC favored a unimodal distribution, while AIC provided equal support for a unimodal and a bimodal distribution. Notably, visualization of the distributions revealed a strong overlap between the two normal distributions under the bimodal model, likely explaining the ambiguity under AIC. Consequently, it is more likely that head-width variation followed a unimodal distribution, indicating there are no disruptive selection pressures for bimodality in the Zeeschelde. As such, eels could not be divided in two distinct head-width groups. Instead, their head widths showed a continuum of narrow to broad with a normal distribution. This pattern was consistent across all maturation stages studied here.
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Affiliation(s)
- Pieterjan Verhelst
- Marine Biology Research Group, Ghent University, Ghent, Belgium.,Research Institute for Nature and Forest, Brussels, Belgium.,Laboratory of Environmental Toxicology and Aquatic Ecology, Ghent University, Ghent, Belgium.,Flanders Marine Institute, Ostend, Belgium
| | - Jens De Meyer
- Evolutionary Morphology of Vertebrates, Ghent University, Ghent, Belgium
| | | | - Johan Coeck
- Research Institute for Nature and Forest, Brussels, Belgium
| | - Peter Goethals
- Laboratory of Environmental Toxicology and Aquatic Ecology, Ghent University, Ghent, Belgium
| | - Tom Moens
- Marine Biology Research Group, Ghent University, Ghent, Belgium
| | - Ans Mouton
- Research Institute for Nature and Forest, Brussels, Belgium
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13
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Kasper C, Colombo M, Aubin-Horth N, Taborsky B. Brain activation patterns following a cooperation opportunity in a highly social cichlid fish. Physiol Behav 2018; 195:37-47. [DOI: 10.1016/j.physbeh.2018.07.025] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2018] [Revised: 07/21/2018] [Accepted: 07/25/2018] [Indexed: 11/24/2022]
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14
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Why do placentas evolve? Evidence for a morphological advantage during pregnancy in live-bearing fish. PLoS One 2018; 13:e0195976. [PMID: 29659620 PMCID: PMC5901924 DOI: 10.1371/journal.pone.0195976] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2017] [Accepted: 04/03/2018] [Indexed: 12/04/2022] Open
Abstract
A live-bearing reproductive strategy can induce large morphological changes in the mother during pregnancy. The evolution of the placenta in swimming animals involves a shift in the timing of maternal provisioning from pre-fertilization (females supply their eggs with sufficient yolk reserves prior to fertilization) to post-fertilization (females provide all nutrients via a placenta during the pregnancy). It has been hypothesised that this shift, associated with the evolution of the placenta, should confer a morphological advantage to the females leading to a more slender body shape during the early stages of pregnancy. We tested this hypothesis by quantifying three-dimensional shape and volume changes during pregnancy and in full-grown virgin controls of two species within the live-bearing fish family Poeciliidae: Poeciliopsis gracilis (non-placental) and Poeciliopsis turneri (placental). We show that P. turneri is more slender than P. gracilis at the beginning of the interbrood interval and in virgins, and that these differences diminish towards the end of pregnancy. This study provides the first evidence for an adaptive morphological advantage of the placenta in live-bearing fish. A similar morphological benefit could drive the evolution of placentas in other live-bearing (swimming) animal lineages.
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15
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Bierbach D, Arias-Rodriguez L, Plath M. Intrasexual competition enhances reproductive isolation between locally adapted populations. Curr Zool 2017; 64:125-133. [PMID: 29492045 PMCID: PMC5809038 DOI: 10.1093/cz/zox071] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 11/22/2017] [Indexed: 02/07/2023] Open
Abstract
During adaptation to different habitat types, both morphological and behavioral traits can undergo divergent selection. Males often fight for status in dominance hierarchies and rank positions predict reproductive success. Ecotypes with reduced fighting abilities should have low reproductive success when migrating into habitats that harbor ecotypes with superior fighting abilities. Livebearing fishes in the Poecilia mexicana-species complex inhabit not only regular freshwater environments, but also independently colonized sulfidic (H2S-containing) habitats in three river drainages. In the current study, we found fighting intensities in staged contests to be considerably lower in some but not all sulfidic surface ecotypes and the sulfidic cave ecotype compared with populations from non-sulfidic surface sites. This is perhaps due to selection imposed by H2S, which hampers oxygen uptake and transport, as well as cellular respiration. Furthermore, migrants from sulfidic habitats may lose fights even if they do not show overall reduced aggressiveness, as physiological performance is likely to be challenged in the non-sulfidic environment to which they are not adapted. To test this hypothesis, we simulated migration of H2S-adapted males into H2S-free waters, as well as H2S-adapted cave-dwelling males into sulfidic surface waters. We found that intruders established dominance less often than resident males, independent of whether or not they showed reduced aggressiveness overall. Our study shows that divergent evolution of male aggressive behavior may also contribute to the maintenance of genetic differentiation in this system and we call for more careful evaluation of male fighting abilities in studies on ecological speciation.
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Affiliation(s)
- David Bierbach
- Department of Biology and Ecology of Fishes, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, 12587 Berlin, Germany
| | - Lenin Arias-Rodriguez
- División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco (UJAT), 86150 Villahermosa, Tabasco, México
| | - Martin Plath
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi 712100, China
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Parsons PJ, Bridle JR, Rüber L, Genner MJ. Evolutionary divergence in life history traits among populations of the Lake Malawi cichlid fish Astatotilapia calliptera. Ecol Evol 2017; 7:8488-8506. [PMID: 29075465 PMCID: PMC5648681 DOI: 10.1002/ece3.3311] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 06/26/2017] [Accepted: 07/12/2017] [Indexed: 12/19/2022] Open
Abstract
During the early stages of adaptive radiation, populations diverge in life history traits such as egg size and growth rates, in addition to eco‐morphological and behavioral characteristics. However, there are few studies of life history divergence within ongoing adaptive radiations. Here, we studied Astatotilapia calliptera, a maternal mouthbrooding cichlid fish within the Lake Malawi haplochromine radiation. This species occupies a rich diversity of habitats, including the main body of Lake Malawi, as well as peripheral rivers and shallow lakes. We used common garden experiments to test for life history divergence among populations, focussing on clutch size, duration of incubation, egg mass, offspring size, and growth rates. In a first experiment, we found significant differences among populations in average clutch size and egg mass, and larger clutches were associated with smaller eggs. In a second experiment, we found significant differences among populations in brood size, duration of incubation, juvenile length when released, and growth rates. Larger broods were associated with smaller juveniles when released and shorter incubation times. Although juvenile growth rates differed between populations, these were not strongly related to initial size on release. Overall, differences in life history characters among populations were not predicted by major habitat classifications (Lake Malawi or peripheral habitats) or population genetic divergence (microsatellite‐based FST). We suggest that the observed patterns are consistent with local selective forces driving the observed patterns of trait divergence. The results provide strong evidence of evolutionary divergence and covariance of life history traits among populations within a radiating cichlid species, highlighting opportunities for further work to identify the processes driving the observed divergence.
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Affiliation(s)
- Paul J Parsons
- School of Biological Sciences University of Bristol Bristol UK.,University of Exeter Penryn UK
| | - Jon R Bridle
- School of Biological Sciences University of Bristol Bristol UK
| | - Lukas Rüber
- Naturhistorisches Museum der Burgergemeinde Bern Bern Switzerland.,Institute of Ecology and Evolution University of Bern Bern Switzerland
| | - Martin J Genner
- School of Biological Sciences University of Bristol Bristol UK
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Göppert C, Harris RM, Theis A, Boila A, Hohl S, Rüegg A, Hofmann HA, Salzburger W, Böhne A. Inhibition of Aromatase Induces Partial Sex Change in a Cichlid Fish: Distinct Functions for Sex Steroids in Brains and Gonads. Sex Dev 2016; 10:97-110. [DOI: 10.1159/000445463] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/18/2016] [Indexed: 11/19/2022] Open
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