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Hetzel C, Forsythe P. Phenotypic plasticity of a generalist fish species resident to lotic environments: Insights from the Great Lakes region. Ecol Evol 2023; 13:e10715. [PMID: 38020680 PMCID: PMC10660395 DOI: 10.1002/ece3.10715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 09/08/2023] [Accepted: 10/04/2023] [Indexed: 12/01/2023] Open
Abstract
Fish morphology is incredibly plastic and local/resident morphology can be influenced by factors including habitat, predation, resource availability, and water velocity. Through analysis of body shape using geometric morphometrics, we describe the degree of phenotypic plasticity within a generalist fish species resident to low-order tributaries of Green Bay and Lake Michigan. We predicted that isolated populations of creek chub (Semotilus atromaculatus) would display plastic responses in body shape due to differences in selective pressures imposed by stream environments. We show that body shape of creek chub was significantly different between streams which are considered to be isolated populations, and while we expected body shape variation to remain constant between study years, we found that shape was not fixed and changed over time in the same manner among focal streams. The diversity of creek chub diet and degree of agricultural land use in the watershed were significant predictors of body morphology. The effect of resource availability and land use within the watershed demonstrates how selective pressures influence phenotypes at the population level. Our study provides insight into morphological changes of stream fish populations, which may be important in the context of changing ecosystems and novel conditions.
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Affiliation(s)
- Claire Hetzel
- Department of Natural and Applied SciencesUniversity of Wisconsin‐Green BayGreen BayWisconsinUSA
| | - Patrick Forsythe
- Department of Natural and Applied SciencesUniversity of Wisconsin‐Green BayGreen BayWisconsinUSA
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2
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Peris Tamayo A, Devineau O, Præbel K, Kahilainen KK, Østbye K. A brain and a head for a different habitat: Size variation in four morphs of Arctic charr ( Salvelinus alpinus (L.)) in a deep oligotrophic lake. Ecol Evol 2020; 10:11335-11351. [PMID: 33144968 PMCID: PMC7593136 DOI: 10.1002/ece3.6771] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 08/05/2020] [Accepted: 08/17/2020] [Indexed: 01/04/2023] Open
Abstract
Adaptive radiation is the diversification of species to different ecological niches and has repeatedly occurred in different salmonid fish of postglacial lakes. In Lake Tinnsjøen, one of the largest and deepest lakes in Norway, the salmonid fish, Arctic charr (Salvelinus alpinus (L.)), has likely radiated within 9,700 years after deglaciation into ecologically and genetically segregated Piscivore, Planktivore, Dwarf, and Abyssal morphs in the pelagial, littoral, shallow-moderate profundal, and deep-profundal habitats. We compared trait variation in the size of the head, the eye and olfactory organs, as well as the volumes of five brain regions of these four Arctic charr morphs. We hypothesised that specific habitat characteristics have promoted divergent body, head, and brain sizes related to utilized depth differing in environmental constraints (e.g., light, oxygen, pressure, temperature, and food quality). The most important ecomorphological variables differentiating morphs were eye area, habitat, and number of lamellae. The Abyssal morph living in the deepest areas of the lake had the smallest brain region volumes, head, and eye size. Comparing the olfactory bulb with the optic tectum in size, it was larger in the Abyssal morph than in the Piscivore morph. The Piscivore and Planktivore morphs that use more illuminated habitats have the largest optic tectum volume, followed by the Dwarf. The observed differences in body size and sensory capacities in terms of vision and olfaction in shallow and deepwater morphs likely relates to foraging and mating habitats in Lake Tinnsjøen. Further seasonal and experimental studies of brain volume in polymorphic species are needed to test the role of plasticity and adaptive evolution behind the observed differences.
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Affiliation(s)
- Ana‐Maria Peris Tamayo
- Faculty of Applied Ecology, Agricultural Sciences and BiotechnologyInland Norway University of Applied SciencesKoppangNorway
- Norwegian College of Fishery Science, Faculty of Biosciences, Fisheries and EconomicsUiT—The Arctic University of NorwayTromsøNorway
| | - Olivier Devineau
- Faculty of Applied Ecology, Agricultural Sciences and BiotechnologyInland Norway University of Applied SciencesKoppangNorway
| | - Kim Præbel
- Norwegian College of Fishery Science, Faculty of Biosciences, Fisheries and EconomicsUiT—The Arctic University of NorwayTromsøNorway
| | | | - Kjartan Østbye
- Faculty of Applied Ecology, Agricultural Sciences and BiotechnologyInland Norway University of Applied SciencesKoppangNorway
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of BiosciencesUniversity of OsloOsloNorway
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3
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Roth-Monzón AJ, Belk MC, Zúñiga-Vega JJ, Johnson JB. Beyond Pairwise Interactions: Multispecies Character Displacement in Mexican Freshwater Fish Communities. Am Nat 2020; 195:983-996. [PMID: 32469659 DOI: 10.1086/708513] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Competition has long been recognized as a central force in shaping evolution, particularly through character displacement. Yet research on character displacement is biased, as it has focused almost exclusively on pairs of interacting species while ignoring multispecies interactions. Communities are seldom so simple that only pairs of species interact, and it is not clear whether inferences from pairwise interactions are sufficient to explain patterns of phenotypes in nature. Here, we test for character displacement in a natural system of freshwater fishes in western Mexico that contains up to four congeneric species of the genus Poeciliopsis. We analyzed body shape differences between populations with different numbers of competitors while accounting for confounding environmental variables. Surprisingly, we found evidence for convergent character displacement in populations of P. prolifica, P. viriosa, and P. latidens. We also found that the convergence in body shape was not consistently in the same direction, meaning that when three or more competitors co-occurred, we did not find more extreme body shapes compared with when there were only two competitors. Instead, when three or more competitors co-occurred, body shape was intermediate between the shape found with a pair of species and the shape found with no competitor present. This intermediate shape suggests that evolution in multispecies communities likely occurs in response to several competitors rather than to simple pairwise interactions. Overall, our results suggest that competition among multiple species is more complex than simple pairwise competitive interactions.
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4
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Camarillo H, Arias Rodriguez L, Tobler M. Functional consequences of phenotypic variation between locally adapted populations: Swimming performance and ventilation in extremophile fish. J Evol Biol 2020; 33:512-523. [DOI: 10.1111/jeb.13586] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 01/06/2020] [Accepted: 01/09/2020] [Indexed: 12/30/2022]
Affiliation(s)
- Henry Camarillo
- Division of Biology Kansas State University Manhattan KS USA
| | - Lenin Arias Rodriguez
- División Académica de Ciencias Biológicas Universidad Juárez Autónoma de Tabasco Villahermosa México
| | - Michael Tobler
- Division of Biology Kansas State University Manhattan KS USA
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5
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Sanchez JL, Trexler JC. When is an herbivore not an herbivore? Detritivory facilitates herbivory in a freshwater system. Ecol Evol 2018; 8:5977-5991. [PMID: 29988405 PMCID: PMC6024117 DOI: 10.1002/ece3.4133] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Revised: 02/13/2018] [Accepted: 03/29/2018] [Indexed: 11/30/2022] Open
Abstract
Herbivory is thought to be an inefficient diet, but it independently evolved from carnivorous ancestors in many metazoan groups, suggesting that plant-eating is adaptive in some circumstances. In this study, we tested two hypotheses to explain the adaptive evolution of herbivory: (i) the Heterotroph Facilitation hypothesis (herbivory is adaptive because herbivores supplement their diets with heterotrophic microbes); and (ii) the Lipid Allocation hypothesis (herbivory is adaptive because algae, which have high lipid concentrations, are nutritionally similar to carnivory). We tested these hypotheses using enclosure cages placed in the Everglades and stocked with Sailfin Mollies (Poecilia latipinna), a native herbivore. Using shading and phosphorus addition (P), we manipulated the heterotrophic microbe and lipid composition of colonizing epiphyton and examined the effects of varying food quality on Sailfin Molly life history. Epiphyton grown in "shade only" conditions had a 55% increase in bacterial fatty acids and 34% lower ratios of saturated + monounsaturated to polyunsaturated fatty acids relative to the other treatments. Ratio of autotroph to heterotroph biovolume varied throughout the experiment, with a 697% increase at 3 weeks and 98% decrease at 6 weeks compared to the other treatments. Gut contents revealed that fish fed selectively on epiphyton to compensate for apparent deficiencies in the available food. Fish raised in "shade only" cages experienced the highest survival, which was best explained by autotrophic biovolume and algal- and bacterial-derived fatty acids at 3 weeks (2-6× more likely than alternative models with ∆AICc > 2.00), and by percentage of bacterial fatty acids in the diet at 6 weeks (3-8× more likely than alternative models with ∆AICc > 2.00). There were no differences in fish growth among treatments. Autotrophic lipids play a role in early fish life history, but we did not find these to be the best predictors of life history later in the juvenile period. Instead, heterotrophic lipids facilitated the herbivorous diet and enhanced survival of juvenile fish in our experiment. Bacterial fatty acid content of the diet promoted herbivore survival, consistent with the Heterotroph Facilitation hypothesis. This is the first study to explicitly contrast Heterotrophic Facilitation and Lipid Allocation hypotheses for the adaptive evolution of herbivory in an aquatic system.
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Affiliation(s)
- Jessica L. Sanchez
- Department of Biological SciencesFlorida International UniversityMiamiFLUSA
| | - Joel C. Trexler
- Department of Biological SciencesFlorida International UniversityMiamiFLUSA
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6
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Zimmer C, Riesch R, Jourdan J, Bierbach D, Arias-Rodriguez L, Plath M. Female Choice Undermines the Emergence of Strong Sexual Isolation between Locally Adapted Populations of Atlantic Mollies ( Poecilia mexicana). Genes (Basel) 2018; 9:E232. [PMID: 29724050 PMCID: PMC5977172 DOI: 10.3390/genes9050232] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 04/23/2018] [Accepted: 04/25/2018] [Indexed: 11/16/2022] Open
Abstract
Divergent selection between ecologically dissimilar habitats promotes local adaptation, which can lead to reproductive isolation (RI). Populations in the Poecilia mexicana species complex have independently adapted to toxic hydrogen sulfide and show varying degrees of RI. Here, we examined the variation in the mate choice component of prezygotic RI. Mate choice tests across drainages (with stimulus males from another drainage) suggest that specific features of the males coupled with a general female preference for yellow color patterns explain the observed variation. Analyses of male body coloration identified the intensity of yellow fin coloration as a strong candidate to explain this pattern, and common-garden rearing suggested heritable population differences. Male sexual ornamentation apparently evolved differently across sulfide-adapted populations, for example because of differences in natural counterselection via predation. The ubiquitous preference for yellow color ornaments in poeciliid females likely undermines the emergence of strong RI, as female discrimination in favor of own males becomes weaker when yellow fin coloration in the respective sulfide ecotype increases. Our study illustrates the complexity of the (partly non-parallel) pathways to divergence among replicated ecological gradients. We suggest that future work should identify the genomic loci involved in the pattern reported here, making use of the increasing genomic and transcriptomic datasets available for our study system.
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Affiliation(s)
- Claudia Zimmer
- College of Animal Science & Technology, Northwest A&F University, Yangling 712100, China.
- Department of Ecology and Evolution, Goethe University of Frankfurt, Max-von-Laue-Straße 13, D-60438 Frankfurt am Main, Germany.
| | - Rüdiger Riesch
- Centre for Ecology, Evolution and Behaviour, School of Biological Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK.
| | - Jonas Jourdan
- Department of River Ecology and Conservation, Senckenberg Research Institute and Natural History Museum Frankfurt, D-63571 Gelnhausen, Germany.
| | - David Bierbach
- Department of Biology and Ecology of Fishes, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, D-12587 Berlin, Germany.
| | - Lenin Arias-Rodriguez
- División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco (UJAT), 86150 Villahermosa, Tabasco, Mexico.
| | - Martin Plath
- College of Animal Science & Technology, Northwest A&F University, Yangling 712100, China.
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, Northwest A&F University, Yangling 712100, China.
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7
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8
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Flanagan SP, Rosenqvist G, Jones AG. Mate quality and the temporal dynamics of breeding in a sex-role-reversed pipefish, S. typhle. Behav Ecol Sociobiol 2016. [DOI: 10.1007/s00265-016-2255-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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9
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Hutchins BT, Engel AS, Nowlin WH, Schwartz BF. Chemolithoautotrophy supports macroinvertebrate food webs and affects diversity and stability in groundwater communities. Ecology 2016; 97:1530-42. [PMID: 27459783 DOI: 10.1890/15-1129.1] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The prevailing paradigm in subterranean ecology is that below-ground food webs are simple, limited to one or two trophic levels, and composed of generalist species because of spatio-temporally patchy food resources and pervasive energy limitation. This paradigm is based on relatively few studies of easily accessible, air-filled caves. However, in some subterranean ecosystems, chemolithoautotrophy can subsidize or replace surface-based allochthonous inputs of photosynthetically derived organic matter (OM) as a basal food resource and promote niche specialization and evolution of higher trophic levels. Consequently, the current subterranean trophic paradigm fails to account for variation in resources, trophic specialization, and food chain length in some subterranean ecosystems. We reevaluated the subterranean food web paradigm by examining spatial variation in the isotopic composition of basal food resources and consumers, food web structure, stygobiont species diversity, and chromophoric organic matter (CDOM), across a geochemical gradient in a large and complex groundwater system, the Edwards Aquifer in Central Texas (USA). Mean δ13C values of stygobiont communities become increasingly more negative along the gradient of photosynthetic OM sources near the aquifer recharge zone to chemolithoautotrophic OM sources closer to the freshwater-saline water interface (FWSWI) between oxygenated freshwater and anoxic, sulfide-rich saline water. Stygobiont community species richness declined with increasing distance from the FWSWI. Bayesian mixing models were used to estimate the relative importance of photosynthetic OM and chemolithoautorophic OM for stygobiont communities at three biogeochemically distinct sites. The contribution of chemolithoautotrophic OM to consumers at these sites ranged between 25% and 69% of total OM utilized and comprised as much as 88% of the diet for one species. In addition, the food web adjacent to the FWSWI had greater trophic diversity when compared to the other two sites. Our results suggest that diverse OM sources and in situ, chemolithoautotrophic OM production can support complex groundwater food webs and increase species richness. Chemolithoautotrophy has been fundamental for the long-term maintenance of species diversity, trophic complexity, and community stability in this subterranean ecosystem, especially during periods of decreased photosynthetic production and groundwater recharge that have occurred over geologic time scales.
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10
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Schulz‐Mirbach T, Eifert C, Riesch R, Farnworth MS, Zimmer C, Bierbach D, Klaus S, Tobler M, Streit B, Indy JR, Arias‐Rodriguez L, Plath M. Toxic hydrogen sulphide shapes brain anatomy: a comparative study of sulphide‐adapted ecotypes in the
Poecilia mexicana
complex. J Zool (1987) 2016. [DOI: 10.1111/jzo.12366] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- T. Schulz‐Mirbach
- Department Biology II Ludwig‐Maximilians‐University Munich Planegg‐Martinsried Germany
| | - C. Eifert
- Ecology and Evolution J. W. Goethe University Frankfurt Frankfurt am Main Germany
| | - R. Riesch
- School of Biological Sciences Royal Holloway University of London Egham UK
| | - M. S. Farnworth
- Göttingen Center for Molecular Biosciences Georg‐August‐University Göttingen Göttingen Germany
| | - C. Zimmer
- Ecology and Evolution J. W. Goethe University Frankfurt Frankfurt am Main Germany
| | - D. Bierbach
- Department of Biology and Ecology of Fishes Leibniz‐Institute of Freshwater Ecology and Inland Fisheries Berlin Germany
| | - S. Klaus
- Ecology and Evolution J. W. Goethe University Frankfurt Frankfurt am Main Germany
| | - M. Tobler
- Division of Biology Kansas State University Manhattan KS USA
| | - B. Streit
- Ecology and Evolution J. W. Goethe University Frankfurt Frankfurt am Main Germany
| | - J. R. Indy
- División Académica de Ciencias Biológicas Universidad Juárez Autónoma de Tabasco (UJAT) Villahermosa Tabasco México
| | - L. Arias‐Rodriguez
- División Académica de Ciencias Biológicas Universidad Juárez Autónoma de Tabasco (UJAT) Villahermosa Tabasco México
| | - M. Plath
- College of Animal Science and Technology Northwest A&F University Yangling China
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11
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Sex-specific local life-history adaptation in surface- and cave-dwelling Atlantic mollies (Poecilia mexicana). Sci Rep 2016; 6:22968. [PMID: 26960566 PMCID: PMC4785371 DOI: 10.1038/srep22968] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 02/22/2016] [Indexed: 11/08/2022] Open
Abstract
Cavefishes have long been used as model organisms showcasing adaptive diversification, but does adaptation to caves also facilitate the evolution of reproductive isolation from surface ancestors? We raised offspring of wild-caught surface- and cave-dwelling ecotypes of the neotropical fish Poecilia mexicana to sexual maturity in a 12-month common garden experiment. Fish were raised under one of two food regimes (high vs. low), and this was crossed with differences in lighting conditions (permanent darkness vs. 12:12 h light:dark cycle) in a 2 × 2 factorial design, allowing us to elucidate potential patterns of local adaptation in life histories. Our results reveal a pattern of sex-specific local life-history adaptation: Surface molly females had the highest fitness in the treatment best resembling their habitat of origin (high food and a light:dark cycle), and suffered from almost complete reproductive failure in darkness, while cave molly females were not similarly affected in any treatment. Males of both ecotypes, on the other hand, showed only weak evidence for local adaptation. Nonetheless, local life-history adaptation in females likely contributes to ecological diversification in this system and other cave animals, further supporting the role of local adaptation due to strong divergent selection as a major force in ecological speciation.
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12
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Passow CN, Greenway R, Arias-Rodriguez L, Jeyasingh PD, Tobler M. Reduction of Energetic Demands through Modification of Body Size and Routine Metabolic Rates in Extremophile Fish. Physiol Biochem Zool 2015; 88:371-83. [PMID: 26052634 DOI: 10.1086/681053] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Variation in energy availability or maintenance costs in extreme environments can exert selection for efficient energy use, and reductions in organismal energy demand can be achieved in two ways: reducing body mass or metabolic suppression. Whether long-term exposure to extreme environmental conditions drives adaptive shifts in body mass or metabolic rates remains an open question. We studied body size variation and variation in routine metabolic rates in locally adapted populations of extremophile fish (Poecilia mexicana) living in toxic, hydrogen sulfide-rich springs and caves. We quantified size distributions and routine metabolic rates in wild-caught individuals from four habitat types. Compared with ancestral populations in nonsulfidic surface habitats, extremophile populations were characterized by significant reductions in body size. Despite elevated metabolic rates in cave fish, the body size reduction precipitated in significantly reduced energy demands in all extremophile populations. Laboratory experiments on common garden-raised fish indicated that elevated routine metabolic rates in cave fish likely have a genetic basis. The results of this study indicate that adaptation to extreme environments directly impacts energy metabolism, with fish living in cave and sulfide spring environments expending less energy overall during routine metabolism.
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Affiliation(s)
- Courtney N Passow
- Department of Zoology, Oklahoma State University, 501 Life Sciences West, Stillwater, Oklahoma 74078; 2División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco, Villahermosa, Tabasco, Mexico
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13
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Correa SB, Betancur-R. R, Mérona BD, Armbruster JW. Diet shift of Red Belly Pacu Piaractus brachypomus (Cuvier, 1818) (Characiformes: Serrasalmidae), a Neotropical fish, in the Sepik-Ramu River Basin, Papua New Guinea. NEOTROPICAL ICHTHYOLOGY 2015. [DOI: 10.1590/1982-0224-20130212] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Introduction of fish species is a globally widespread practice that causes losses of native species and homogenization of diversity within and across continents. Diet assessments are important tools to depict the ecological function of species introduced into novel ecosystem and possible direct and indirect ecological effects. In this study, we compare the diet of Piaractus brachypomus, a mainly frugivorous Neotropical fish, introduced into the Sepik-Ramu River Basin (Papua New Guinea) nearly two decades ago, to that of similar size individuals from Neotropical populations in the Amazon and Orinoco River basins (South America). In contrast to native populations that feed mainly on terrestrial plants and invertebrates, the diet of introduced P. brachypomus is mainly composed of fish remains and aquatic plants, while terrestrial plants are frequently consumed but in relatively smaller amounts. These findings show that P. brachypomus has an inherently plastic diet that can be adjusted when displaced to a novel geographic area. While trophic plasticity increases the likelihood of a species to establish breeding populations after its introduction, it also reduces our ability to predict negative effects on native species.
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14
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Eifert C, Farnworth M, Schulz-Mirbach T, Riesch R, Bierbach D, Klaus S, Wurster A, Tobler M, Streit B, Indy JR, Arias-Rodriguez L, Plath M. Brain size variation in extremophile fish: local adaptation versus phenotypic plasticity. J Zool (1987) 2014. [DOI: 10.1111/jzo.12190] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- C. Eifert
- Department of Ecology and Evolution; J.W. Goethe University Frankfurt; Frankfurt am Main Germany
| | - M. Farnworth
- Department of Ecology and Evolution; J.W. Goethe University Frankfurt; Frankfurt am Main Germany
| | - T. Schulz-Mirbach
- Department Biology II; Ludwig-Maximilians-University; Planegg Germany
| | - R. Riesch
- Department of Animal and Plant Sciences; University of Sheffield; Sheffield UK
- School of Biological Sciences; Centre for Ecology, Evolution and Behaviour; Royal Holloway University of London; Egham Surrey UK
| | - D. Bierbach
- Department of Ecology and Evolution; J.W. Goethe University Frankfurt; Frankfurt am Main Germany
- Department of Biology and Ecology of Fishes, Leibniz-Institute of Freshwater Ecology and Inland Fisheries; Berlin Germany
| | - S. Klaus
- Department of Ecology and Evolution; J.W. Goethe University Frankfurt; Frankfurt am Main Germany
| | - A. Wurster
- Department of Ecology and Evolution; J.W. Goethe University Frankfurt; Frankfurt am Main Germany
| | - M. Tobler
- Department of Zoology; Oklahoma State University; Stillwater OK USA
| | - B. Streit
- Department of Ecology and Evolution; J.W. Goethe University Frankfurt; Frankfurt am Main Germany
| | - J. R. Indy
- División Académica de Ciencias Biológicas; Universidad Juárez Autónoma de Tabasco (UJAT); Villahermosa Tabasco México
| | - L. Arias-Rodriguez
- División Académica de Ciencias Biológicas; Universidad Juárez Autónoma de Tabasco (UJAT); Villahermosa Tabasco México
| | - M. Plath
- College of Animal Science and Technology; Northwest A&F University; Yangling China
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15
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Culumber ZW, Bautista-Hernández CE, Monks S, Arias-Rodriguez L, Tobler M. Variation in Melanism and Female Preference in Proximate but Ecologically Distinct Environments. Ethology 2014. [DOI: 10.1111/eth.12282] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Zachary W. Culumber
- Centro de Investigaciones Cientificas de las Huastecas “Aguazarca”; Calnali Hidalgo Mexico
- Centro de Investigaciones Biologicas; Universidad Autónoma del Estado de Hidalgo; Pachuca Hidalgo Mexico
| | - Christian E. Bautista-Hernández
- Centro de Investigaciones Cientificas de las Huastecas “Aguazarca”; Calnali Hidalgo Mexico
- Centro de Investigaciones Biologicas; Universidad Autónoma del Estado de Hidalgo; Pachuca Hidalgo Mexico
| | - Scott Monks
- Centro de Investigaciones Biologicas; Universidad Autónoma del Estado de Hidalgo; Pachuca Hidalgo Mexico
| | - Lenin Arias-Rodriguez
- División Académica de Ciencias Biológicas; Universidad Juárez Autónoma de Tabasco (UJAT); Villahermosa Tabasco Mexico
| | - Michael Tobler
- Department of Zoology; Oklahoma State University; Stillwater OK USA
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16
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Patterns of Macroinvertebrate and Fish Diversity in Freshwater Sulphide Springs. DIVERSITY-BASEL 2014. [DOI: 10.3390/d6030597] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Extreme environments are characterised by the presence of physicochemical stressors and provide unique study systems to address problems in evolutionary ecology research. Sulphide springs provide an example of extreme freshwater environments; because hydrogen sulphide’s adverse physiological effects induce mortality in metazoans even at micromolar concentrations. Sulphide springs occur worldwide, but while microbial communities in sulphide springs have received broad attention, little is known about macroinvertebrates and fish inhabiting these toxic environments. We reviewed qualitative occurrence records of sulphide spring faunas on a global scale and present a quantitative case study comparing diversity patterns in sulphidic and adjacent non-sulphidic habitats across replicated river drainages in Southern Mexico. While detailed studies in most regions of the world remain scarce, available data suggests that sulphide spring faunas are characterised by low species richness. Dipterans (among macroinvertebrates) and cyprinodontiforms (among fishes) appear to dominate the communities in these habitats. At least in fish, there is evidence for the presence of highly endemic species and populations exclusively inhabiting sulphide springs. We provide a detailed discussion of traits that might predispose certain taxonomic groups to colonize sulphide springs, how colonizers subsequently adapt to cope with sulphide toxicity, and how adaptation may be linked to speciation processes.
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17
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Gradient evolution of body colouration in surface- and cave-dwelling Poecilia mexicana and the role of phenotype-assortative female mate choice. BIOMED RESEARCH INTERNATIONAL 2013; 2013:148348. [PMID: 24175282 PMCID: PMC3794506 DOI: 10.1155/2013/148348] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Accepted: 08/16/2013] [Indexed: 12/11/2022]
Abstract
Ecological speciation assumes reproductive isolation to be the product of ecologically based divergent selection. Beside natural selection, sexual selection via phenotype-assortative mating is thought to promote reproductive isolation. Using the neotropical fish Poecilia mexicana from a system that has been described to undergo incipient ecological speciation in adjacent, but ecologically divergent habitats characterized by the presence or absence of toxic H2S and darkness in cave habitats, we demonstrate a gradual change in male body colouration along the gradient of light/darkness, including a reduction of ornaments that are under both inter- and intrasexual selection in surface populations. In dichotomous choice tests using video-animated stimuli, we found surface females to prefer males from their own population over the cave phenotype. However, female cave fish, observed on site via infrared techniques, preferred to associate with surface males rather than size-matched cave males, likely reflecting the female preference for better-nourished (in this case: surface) males. Hence, divergent selection on body colouration indeed translates into phenotype-assortative mating in the surface ecotype, by selecting against potential migrant males. Female cave fish, by contrast, do not have a preference for the resident male phenotype, identifying natural selection against migrants imposed by the cave environment as the major driver of the observed reproductive isolation.
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Palacios M, Arias-Rodriguez L, Plath M, Eifert C, Lerp H, Lamboj A, Voelker G, Tobler M. The rediscovery of a long described species reveals additional complexity in speciation patterns of poeciliid fishes in sulfide springs. PLoS One 2013; 8:e71069. [PMID: 23976979 PMCID: PMC3745397 DOI: 10.1371/journal.pone.0071069] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Accepted: 07/01/2013] [Indexed: 12/02/2022] Open
Abstract
The process of ecological speciation drives the evolution of locally adapted and reproductively isolated populations in response to divergent natural selection. In Southern Mexico, several lineages of the freshwater fish species of the genus Poecilia have independently colonized toxic, hydrogen sulfide-rich springs. Even though ecological speciation processes are increasingly well understood in this system, aligning the taxonomy of these fish with evolutionary processes has lagged behind. While some sulfide spring populations are classified as ecotypes of Poecilia mexicana, others, like P. sulphuraria, have been described as highly endemic species. Our study particularly focused on elucidating the taxonomy of the long described sulfide spring endemic, Poecilia thermalis Steindachner 1863, and investigates if similar evolutionary patterns of phenotypic trait divergence and reproductive isolation are present as observed in other sulfidic species of Poecilia. We applied a geometric morphometric approach to assess body shape similarity to other sulfidic and non-sulfidic fish of the genus Poecilia. We also conducted phylogenetic and population genetic analyses to establish the phylogenetic relationships of P. thermalis and used a population genetic approach to determine levels of gene flow among Poecilia from sulfidic and non-sulfidic sites. Our results indicate that P. thermalis' body shape has evolved in convergence with other sulfide spring populations in the genus. Phylogenetic analyses placed P. thermalis as most closely related to one population of P. sulphuraria, and population genetic analyses demonstrated that P. thermalis is genetically isolated from both P. mexicana ecotypes and P. sulphuraria. Based on these findings, we make taxonomic recommendations for P. thermalis. Overall, our study verifies the role of hydrogen sulfide as a main factor shaping convergent, phenotypic evolution and the emergence of reproductive isolation between Poecilia populations residing in adjacent sulfidic and non-sulfidic environments.
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Affiliation(s)
- Maura Palacios
- Department of Wildlife and Fisheries Sciences, Texas A&M University, College Station, Texas, United States of America
- * E-mail:
| | - Lenin Arias-Rodriguez
- División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco, Villahermosa, Tabasco, México
| | - Martin Plath
- Evolutionary Ecology Group, J. W. Goethe University Frankfurt am Main, Frankfurt, Hessen, Germany
| | - Constanze Eifert
- Evolutionary Ecology Group, J. W. Goethe University Frankfurt am Main, Frankfurt, Hessen, Germany
| | - Hannes Lerp
- Evolutionary Ecology Group, J. W. Goethe University Frankfurt am Main, Frankfurt, Hessen, Germany
| | - Anton Lamboj
- Department for Integrative Zoology, University of Vienna, Vienna, Austria
| | - Gary Voelker
- Department of Wildlife and Fisheries Sciences, Texas A&M University, College Station, Texas, United States of America
| | - Michael Tobler
- Department of Zoology, Oklahoma State University, Stillwater, Oklahoma, United States of America
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Plath M, Pfenninger M, Lerp H, Riesch R, Eschenbrenner C, Slattery PA, Bierbach D, Herrmann N, Schulte M, Arias-Rodriguez L, Rimber Indy J, Passow C, Tobler M. Genetic differentiation and selection against migrants in evolutionarily replicated extreme environments. Evolution 2013; 67:2647-61. [PMID: 24033173 DOI: 10.1111/evo.12133] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Accepted: 04/02/2013] [Indexed: 01/18/2023]
Abstract
We investigated mechanisms of reproductive isolation in livebearing fishes (genus Poecilia) inhabiting sulfidic and nonsulfidic habitats in three replicate river drainages. Although sulfide spring fish convergently evolved divergent phenotypes, it was unclear if mechanisms of reproductive isolation also evolved convergently. Using microsatellites, we found strongly reduced gene flow between adjacent populations from different habitat types, suggesting that local adaptation to sulfidic habitats repeatedly caused the emergence of reproductive isolation. Reciprocal translocation experiments indicate strong selection against immigrants into sulfidic waters, but also variation among drainages in the strength of selection against immigrants into nonsulfidic waters. Mate choice experiments revealed the evolution of assortative mating preferences in females from nonsulfidic but not from sulfidic habitats. The inferred strength of sexual selection against immigrants (RI(s)) was negatively correlated with the strength of natural selection (RI(m)), a pattern that could be attributed to reinforcement, whereby natural selection strengthens behavioral isolation due to reduced hybrid fitness. Overall, reproductive isolation and genetic differentiation appear to be replicated and direct consequences of local adaptation to sulfide spring environments, but the relative contributions of different mechanisms of reproductive isolation vary across these evolutionarily independent replicates, highlighting both convergent and nonconvergent evolutionary trajectories of populations in each drainage.
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Affiliation(s)
- Martin Plath
- J. W. Goethe-University Frankfurt/M., Evolutionary Ecology Group, Max-von-Laue Str. 13, 60438, Frankfurt, a. M., Germany.
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Scharnweber K, Plath M, Winemiller KO, Tobler M. Dietary niche overlap in sympatric asexual and sexual livebearing fishes Poecilia spp. JOURNAL OF FISH BIOLOGY 2011; 79:1760-1773. [PMID: 22141886 DOI: 10.1111/j.1095-8649.2011.03114.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The present study investigated the spatiotemporal patterns in trophic resource use in a system of a gynogenetic poeciliid fish, the Amazon molly Poecilia formosa, and its sexual congeners the sailfin molly Poecilia latipinna and the Atlantic molly Poecilia mexicana using gut contents analysis. No statistically significant differences in trophic resource use were found between sexual and gynogenetic species, but gut contents varied significantly across sites and over time. In addition, variation in trophic morphology (i.e. gut length) was significant across sites but not species, and laboratory experiments indicated that gut length is phenotypically plastic. Overall, trophic differentiation between coexisting asexual and sexual Poecilia appears to be minimal, and it is unlikely that niche differentiation contributes to a stable coexistence of the two reproductive forms.
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Affiliation(s)
- K Scharnweber
- Department of Biology and Ecology of Fishes, Leibniz Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, 12587 Berlin, Germany.
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Roach KA, Tobler M, Winemiller KO. Hydrogen sulfide, bacteria, and fish: a unique, subterranean food chain. Ecology 2011; 92:2056-62. [DOI: 10.1890/11-0276.1] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Divergent evolution of male aggressive behaviour: another reproductive isolation barrier in extremophile poeciliid fishes? INTERNATIONAL JOURNAL OF EVOLUTIONARY BIOLOGY 2011; 2012:148745. [PMID: 22315695 PMCID: PMC3270405 DOI: 10.1155/2012/148745] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Revised: 09/20/2011] [Accepted: 10/14/2011] [Indexed: 11/17/2022]
Abstract
Reproductive isolation among locally adapted populations may arise when immigrants from foreign habitats are selected against via natural or (inter-)sexual selection (female mate choice). We asked whether also intrasexual selection through male-male competition could promote reproductive isolation among populations of poeciliid fishes that are locally adapted to extreme environmental conditions [i.e., darkness in caves and/or toxic hydrogen sulphide (H(2)S)]. We found strongly reduced aggressiveness in extremophile P. oecilia mexicana, and darkness was the best predictor for the evolutionary reduction of aggressiveness, especially when combined with presence of H(2)S. We demonstrate that reduced aggression directly translates into migrant males being inferior when paired with males from non-sulphidic surface habitats. By contrast, the phylogenetically old sulphur endemic P. sulphuraria from another sulphide spring area showed no overall reduced aggressiveness, possibly indicating evolved mechanisms to better cope with H(2)S.
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Mustached males in a tropical poeciliid fish: emerging female preference selects for a novel male trait. Behav Ecol Sociobiol 2011. [DOI: 10.1007/s00265-011-1154-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Riesch R, Plath M, Schlupp I. Toxic hydrogen sulphide and dark caves: pronounced male life-history divergence among locally adapted Poecilia mexicana (Poeciliidae). J Evol Biol 2010; 24:596-606. [PMID: 21159007 DOI: 10.1111/j.1420-9101.2010.02194.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Chronic environmental stress is known to induce evolutionary change. Here, we assessed male life-history trait divergence in the neotropical fish Poecilia mexicana from a system that has been described to undergo incipient ecological speciation in adjacent, but reproductively isolated toxic/nontoxic and surface/cave habitats. Examining both field-caught and common garden-reared specimens, we investigated the extent of differentiation and plasticity of life-history strategies employed by male P. mexicana. We found strong site-specific life-history divergence in traits such as fat content, standard length and gonadosomatic index. The majority of site-specific life-history differences were also expressed under common garden-rearing conditions. We propose that apparent conservatism of male life histories is the result of other (genetically based) changes in physiology and behaviour between populations. Together with the results from previous studies, this is strong evidence for local adaptation as a result of ecologically based divergent selection.
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Affiliation(s)
- R Riesch
- Department of Zoology, University of Oklahoma, Norman, OK, USA.
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Plath M, Hermann B, Schröder C, Riesch R, Tobler M, García de León FJ, Schlupp I, Tiedemann R. Locally adapted fish populations maintain small-scale genetic differentiation despite perturbation by a catastrophic flood event. BMC Evol Biol 2010; 10:256. [PMID: 20731863 PMCID: PMC2936308 DOI: 10.1186/1471-2148-10-256] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2010] [Accepted: 08/23/2010] [Indexed: 11/21/2022] Open
Abstract
Background Local adaptation to divergent environmental conditions can promote population genetic differentiation even in the absence of geographic barriers and hence, lead to speciation. Perturbations by catastrophic events, however, can distort such parapatric ecological speciation processes. Here, we asked whether an exceptionally strong flood led to homogenization of gene pools among locally adapted populations of the Atlantic molly (Poecilia mexicana, Poeciliidae) in the Cueva del Azufre system in southern Mexico, where two strong environmental selection factors (darkness within caves and/or presence of toxic H2S in sulfidic springs) drive the diversification of P. mexicana. Nine nuclear microsatellites as well as heritable female life history traits (both as a proxy for quantitative genetics and for trait divergence) were used as markers to compare genetic differentiation, genetic diversity, and especially population mixing (immigration and emigration) before and after the flood. Results Habitat type (i.e., non-sulfidic surface, sulfidic surface, or sulfidic cave), but not geographic distance was the major predictor of genetic differentiation. Before and after the flood, each habitat type harbored a genetically distinct population. Only a weak signal of individual dislocation among ecologically divergent habitat types was uncovered (with the exception of slightly increased dislocation from the Cueva del Azufre into the sulfidic creek, El Azufre). By contrast, several lines of evidence are indicative of increased flood-induced dislocation within the same habitat type, e.g., between different cave chambers of the Cueva del Azufre. Conclusions The virtual absence of individual dislocation among ecologically different habitat types indicates strong natural selection against migrants. Thus, our current study exemplifies that ecological speciation in this and other systems, in which extreme environmental factors drive speciation, may be little affected by temporary perturbations, as adaptations to physico-chemical stressors may directly affect the survival probability in divergent habitat types.
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Affiliation(s)
- Martin Plath
- Institute of Biochemistry & Biology, Unit of Evolutionary Biology/Systematic Zoology, University of Potsdam, Karl-Liebknecht Str 24-25, D-14476 Potsdam, Germany
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Complementary effect of natural and sexual selection against immigrants maintains differentiation between locally adapted fish. Naturwissenschaften 2010; 97:769-74. [PMID: 20574847 DOI: 10.1007/s00114-010-0691-x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2010] [Revised: 06/09/2010] [Accepted: 06/10/2010] [Indexed: 10/19/2022]
Abstract
Adaptation to ecologically heterogeneous environments can drive speciation. But what mechanisms maintain reproductive isolation among locally adapted populations? Using poeciliid fishes in a system with naturally occurring toxic hydrogen sulfide, we show that (a) fish from non-sulfidic sites (Poecilia mexicana) show high mortality (95 %) after 24 h when exposed to the toxicant, while locally adapted fish from sulfidic sites (Poecilia sulphuraria) experience low mortality (13 %) when transferred to non-sulfidic water. (b) Mate choice tests revealed that P. mexicana females exhibit a preference for conspecific males in non-sulfidic water, but not in sulfidic water, whereas P. sulphuraria females never showed a preference. Increased costs of mate choice in sulfidic, hypoxic water, and the lack of selection for reinforcement due to the low survival of P. mexicana may explain the absence of a preference in P. sulphuraria females. Taken together, our study may be the first to demonstrate independent-but complementary-effects of natural and sexual selection against immigrants maintaining differentiation between locally adapted fish populations.
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Alcalde L, Derocco NN, Rosset SD. Feeding in Syntopy: Diet of Hydromedusa tectifera and Phrynops hilarii (Chelidae). CHELONIAN CONSERVATION AND BIOLOGY 2010. [DOI: 10.2744/ccb-0794.1] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Riesch R, Plath M, Schlupp I. Toxic hydrogen sulfide and dark caves: life-history adaptations in a livebearing fish (Poecilia mexicana, Poeciliidae). Ecology 2010; 91:1494-505. [PMID: 20503881 DOI: 10.1890/09-1008.1] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Rüdiger Riesch
- Graduate Program in Ecology and Evolutionary Biology, Department of Zoology, University of Oklahoma, 730 Van Vleet Oval, Norman, Oklahoma 73019, USA.
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Convergent life-history shifts: toxic environments result in big babies in two clades of poeciliids. Naturwissenschaften 2009; 97:133-41. [PMID: 19826772 DOI: 10.1007/s00114-009-0613-y] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2009] [Revised: 09/21/2009] [Accepted: 09/23/2009] [Indexed: 10/20/2022]
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Tobler M, Riesch R, Tobler CM, Schulz-Mirbach T, Plath M. Natural and sexual selection against immigrants maintains differentiation among micro-allopatric populations. J Evol Biol 2009; 22:2298-304. [PMID: 19807829 DOI: 10.1111/j.1420-9101.2009.01844.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Local adaptation to divergent environmental conditions can promote population genetic differentiation even in the absence of geographic barriers and hence lead to speciation. But what mechanisms contribute to reproductive isolation among diverging populations? We tested for natural and sexual selection against immigrants in a fish species inhabiting (and adapting to) nonsulphidic surface habitats, sulphidic surface habitats and a sulphidic cave. Gene flow is strong among sample sites situated within the same habitat type, but low among divergent habitat types. Our results indicate that females of both sulphidic populations discriminate against immigrant males during mate choice. Furthermore, using reciprocal translocation experiments, we document natural selection against migrants between nonsulphidic and sulphidic habitats, whereas migrants between sulphidic cave and surface habitats did not exhibit increased mortality within the same time period. Consequently, both natural and sexual selection may contribute to isolation among parapatric populations, and selection against immigrants may be a powerful mechanism facilitating speciation among locally adapted populations even over very small spatial distances.
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Affiliation(s)
- M Tobler
- Department of Biology and Department of Wildlife and Fisheries Sciences, Texas A&M University, College Station, TX 77843, USA
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Tobler M, Coleman SW, Perkins BD, Rosenthal GG. Reduced opsin gene expression in a cave-dwelling fish. Biol Lett 2009; 6:98-101. [PMID: 19740890 DOI: 10.1098/rsbl.2009.0549] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Regressive evolution of structures associated with vision in cave-dwelling organisms is the focus of intense research. Most work has focused on differences between extreme visual phenotypes: sighted, surface animals and their completely blind, cave-dwelling counterparts. We suggest that troglodytic systems, comprising multiple populations that vary along a gradient of visual function, may prove critical in understanding the mechanisms underlying initial regression in visual pathways. Gene expression assays of natural and laboratory-reared populations of the Atlantic molly (Poecilia mexicana) revealed reduced opsin expression in cave-dwelling populations compared with surface-dwelling conspecifics. Our results suggest that the reduction in opsin expression in cave-dwelling populations is not phenotypically plastic but reflects a hardwired system not rescued by exposure to light during retinal ontogeny. Changes in opsin gene expression may consequently represent a first evolutionary step in the regression of eyes in cave organisms.
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Affiliation(s)
- Michael Tobler
- Department of Biology, Texas A&M University, , College Station, TX 77843, USA.
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Variation along the shy–bold continuum in extremophile fishes (Poecilia mexicana, Poecilia sulphuraria). Behav Ecol Sociobiol 2009. [DOI: 10.1007/s00265-009-0780-z] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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