1
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Functional morphology of prey capture in stream-dwelling sailfin silversides (Telmatherinidae) based on high-speed video recordings. ZOOMORPHOLOGY 2022. [DOI: 10.1007/s00435-022-00570-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/10/2022]
Abstract
AbstractUnderstanding how ecology shapes the evolution of morphological traits is a major goal in organismal biology. By quantifying force of motion, hypotheses on the function of fundamental tasks of animals like feeding can be tested. Ray-finned fishes use various feeding strategies, classified into three main feeding modes: suction, ram and manipulation. While manipulation feeders are usually distinct in morphology and feeding behavior, differentiation between suction and ram feeders is often fine-scaled and transitional. Previous studies have identified different feeding modes and biomechanical adaptations on interspecific and intersexual levels in lake-dwelling sailfin silversides, species of a Sulawesi freshwater radiation. Functional feeding morphology of stream-dwelling species remained in contrast unstudied. We hypothesized that different requirements of riverine habitats favor the evolution of alternative functional adaptations in stream-dwelling sailfin silversides. To test this hypothesis, we investigated feeding of two phenotypically distinct riverine species, Telmatherina bonti and Marosatherina ladigesi, and their sexes, by high-speed videos and biomechanical models. The kinematic approaches identify T. bonti as ram feeder and M. ladigesi as suction feeder. Surprisingly, the biomechanical models of the jaw apparatus provide contradicting results: only one out of three studied parameters varies between both species. Contrarily to lake-dwelling Telmatherina, sexes of both species do not differ in feeding biomechanics. We conclude that T. bonti predominantly uses ram feeding while M. ladigesi primarily uses suction feeding as its main hunting strategy. Feeding biomechanics of stream-dwelling sailfin silversides are less distinct compared to lake-dwelling species, likely due to different trophic ecologies or less stable ecological conditions.
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2
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Santos-Santos JH, Audenaert L, Verheyen E, Adriaens D. Ontogenetic divergence generates novel phenotypes in hybrid cichlids. J Anat 2021; 238:1116-1127. [PMID: 33417249 PMCID: PMC8053579 DOI: 10.1111/joa.13375] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 11/10/2020] [Accepted: 11/16/2020] [Indexed: 12/20/2022] Open
Abstract
Hybridization is suggested to contribute to ecomorphological and taxonomic diversity in lacustrine East African cichlids. This is supported by studies demonstrating that genetic diversity within lake radiations has been influenced by hybridization events, leading to extensive phenotypic differentiation of genetically closely related species. Hybrid persistence and speciation in sympatry with gene flow can be explained by pleiotropy in traits involved in reproductive isolation; however, little attention has been given to how trait differentiation is established during hybrid ontogeny, and how this may relate to trophic and locomotor specialization. This study compares body shape changes in a Lake Victoria cichlid hybrid throughout its post-hatch ontogeny to those of its parental species. Across the considered age/size categories, hybrids occupy a distinct and intermediate morphological space, yet where several transgressive traits emerge. A between-group principal component analysis on body shapes across size categories reveals axes of shape variation exclusive to the hybrids in the youngest/smallest size categories. Shape differences in the hybrids involved morphological traits known to be implicated in trophic and locomotor specializations in the parental species. Combined, our findings suggest that phenotypic divergence in the hybrid can lead to functional differences that may potentially release them to some degree from competition with the parental species. These findings agree with recent literature that addresses the potential importance of hybridization for the unusually recent origin of the Lake Victoria cichlid super-species flock.
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Affiliation(s)
- Javier H Santos-Santos
- Evolutionary Morphology of Vertebrates, Ghent University, Gent, Belgium.,Department of Biogeography and Global Change, Museo Nacional de Ciencias Naturales, Consejo Superior de Investigaciones Científicas (MNCN-CSIC), Madrid, Spain
| | - Leen Audenaert
- OD Taxonomy and Phylogeny, Vertebrates, Royal Belgian Institute of Natural Sciences, Brussels, Belgium
| | - Erik Verheyen
- OD Taxonomy and Phylogeny, Vertebrates, Royal Belgian Institute of Natural Sciences, Brussels, Belgium.,Evolutionary Ecology Group, Biology Department, University of Antwerp, Antwerp, Belgium
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3
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Martin CH, Gould KJ. Surprising spatiotemporal stability of a multi-peak fitness landscape revealed by independent field experiments measuring hybrid fitness. Evol Lett 2020; 4:530-544. [PMID: 33312688 PMCID: PMC7719547 DOI: 10.1002/evl3.195] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 07/23/2020] [Accepted: 09/14/2020] [Indexed: 12/14/2022] Open
Abstract
The effect of the environment on fitness in natural populations is a fundamental question in evolutionary biology. However, experimental manipulations of both environment and phenotype at the same time are rare. Thus, the relative importance of the competitive environment versus intrinsic organismal performance in shaping the location, height, and fluidity of fitness peaks and valleys remains largely unknown. Here, we experimentally tested the effect of competitor frequency on the complex fitness landscape driving adaptive radiation of a generalist and two trophic specialist pupfishes, a scale-eater and molluscivore, endemic to hypersaline lakes on San Salvador Island (SSI), Bahamas. We manipulated phenotypes, by generating 3407 F4/F5 lab-reared hybrids, and competitive environment, by altering the frequency of rare transgressive hybrids between field enclosures in two independent lake populations. We then tracked hybrid survival and growth rates across these four field enclosures for 3-11 months. In contrast to competitive speciation theory, we found no evidence that the frequency of hybrid phenotypes affected their survival. Instead, we observed a strikingly similar fitness landscape to a previous independent field experiment, each supporting multiple fitness peaks for generalist and molluscivore phenotypes and a large fitness valley isolating the divergent scale-eater phenotype. These features of the fitness landscape were stable across manipulated competitive environments, multivariate trait axes, and spatiotemporal heterogeneity. We suggest that absolute performance constraints and divergent gene regulatory networks shape macroevolutionary (interspecific) fitness landscapes in addition to microevolutionary (intraspecific) competitive dynamics. This interplay between organism and environment underlies static and dynamic features of the adaptive landscape.
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Affiliation(s)
- Christopher H. Martin
- Department of Integrative BiologyUniversity of California, BerkeleyBerkeleyCalifornia94720
- Museum of Vertebrate ZoologyUniversity of California, BerkeleyBerkeleyCalifornia94720
| | - Katelyn J. Gould
- Department of BiologyUniversity of North Carolina at Chapel HillChapel HillNorth Carolina27515
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4
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Ito T, Kanthaswamy S, Bunlungsup S, Oldt RF, Houghton P, Hamada Y, Malaivijitnond S. Secondary contact and genomic admixture between rhesus and long-tailed macaques in the Indochina Peninsula. J Evol Biol 2020; 33:1164-1179. [PMID: 33448526 DOI: 10.1111/jeb.13681] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Revised: 06/11/2020] [Accepted: 07/08/2020] [Indexed: 01/07/2023]
Abstract
Understanding the process and consequences of hybridization is one of the major challenges in evolutionary biology. A growing body of literature has reported evidence of ancient hybridization events or natural hybrid zones in primates, including humans; however, we still have relatively limited knowledge about the pattern and history of admixture because there have been little studies that simultaneously achieved genome-scale analysis and a geographically wide sampling of wild populations. Our study applied double-digest restriction site-associated DNA sequencing to samples from the six localities in and around the provisional hybrid zone of rhesus and long-tailed macaques and evaluated population structure, phylogenetic relationships, demographic history, and geographic clines of morphology and allele frequencies. A latitudinal gradient of genetic components was observed, highlighting the transition from rhesus (north) to long-tailed macaque distribution (south) as well as the presence of one northern population of long-tailed macaques exhibiting unique genetic structure. Interspecific gene flow was estimated to have recently occurred after an isolation period, and the migration rate from rhesus to long-tailed macaques was slightly greater than in the opposite direction. Although some rhesus macaque-biased alleles have widely introgressed into long-tailed macaque populations, the inflection points of allele frequencies have been observed as concentrated around the traditionally recognized interspecific boundary where morphology discontinuously changed; this pattern was more pronounced in the X chromosome than in autosomes. Thus, due to geographic separation before secondary contact, reproductive isolation could have evolved, contributing to the maintenance of an interspecific boundary and species-specific morphological characteristics.
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Affiliation(s)
- Tsuyoshi Ito
- Department of Evolution and Phylogeny, Primate Research Institute, Kyoto University, Aichi, Japan
| | - Sreetharan Kanthaswamy
- School of Mathematical and Natural Sciences, New College of Interdisciplinary Arts and Sciences, Arizona State University West Campus, Glendale, AZ, USA
| | - Srichan Bunlungsup
- Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok, Thailand.,National Primate Research Center of Thailand-Chulalongkorn University, Saraburi, Thailand
| | - Robert F Oldt
- School of Mathematical and Natural Sciences, New College of Interdisciplinary Arts and Sciences, Arizona State University West Campus, Glendale, AZ, USA
| | | | - Yuzuru Hamada
- Department of Evolution and Phylogeny, Primate Research Institute, Kyoto University, Aichi, Japan
| | - Suchinda Malaivijitnond
- Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok, Thailand.,National Primate Research Center of Thailand-Chulalongkorn University, Saraburi, Thailand
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5
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Feller AF, Selz OM, McGee MD, Meier JI, Mwaiko S, Seehausen O. Rapid generation of ecologically relevant behavioral novelty in experimental cichlid hybrids. Ecol Evol 2020; 10:7445-7462. [PMID: 32760540 PMCID: PMC7391563 DOI: 10.1002/ece3.6471] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 05/15/2020] [Accepted: 05/16/2020] [Indexed: 01/25/2023] Open
Abstract
The East African cichlid radiations are characterized by repeated and rapid diversification into many distinct species with different ecological specializations and by a history of hybridization events between nonsister species. Such hybridization might provide important fuel for adaptive radiation. Interspecific hybrids can have extreme trait values or novel trait combinations and such transgressive phenotypes may allow some hybrids to explore ecological niches neither of the parental species could tap into. Here, we investigate the potential of second-generation (F2) hybrids between two generalist cichlid species from Lake Malawi to exploit a resource neither parental species is specialized on: feeding by sifting sand. Some of the F2 hybrids phenotypically resembled fish of species that are specialized on sand sifting. We combined experimental behavioral and morphometric approaches to test whether the F2 hybrids are transgressive in both morphology and behavior related to sand sifting. We then performed a quantitative trait loci (QTL) analysis using RADseq markers to investigate the genetic architecture of morphological and behavioral traits. We show that transgression is present in several morphological traits, that novel trait combinations occur, and we observe transgressive trait values in sand sifting behavior in some of the F2 hybrids. Moreover, we find QTLs for morphology and for sand sifting behavior, suggesting the existence of some loci with moderate to large effects. We demonstrate that hybridization has the potential to rapidly generate novel and ecologically relevant phenotypes that may be suited to a niche neither of the parental species occupies. Interspecific hybridization may thereby contribute to the rapid generation of ecological diversity in cichlid radiations.
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Affiliation(s)
- Anna F. Feller
- Division of Aquatic Ecology and EvolutionInstitute of Ecology and EvolutionUniversity of BernBernSwitzerland
- Department of Fish Ecology and EvolutionCentre of Ecology, Evolution and BiogeochemistryEAWAG Swiss Federal Institute of Aquatic Science and TechnologyKastanienbaumSwitzerland
| | - Oliver M. Selz
- Department of Fish Ecology and EvolutionCentre of Ecology, Evolution and BiogeochemistryEAWAG Swiss Federal Institute of Aquatic Science and TechnologyKastanienbaumSwitzerland
| | - Matthew D. McGee
- Department of Fish Ecology and EvolutionCentre of Ecology, Evolution and BiogeochemistryEAWAG Swiss Federal Institute of Aquatic Science and TechnologyKastanienbaumSwitzerland
- School of Biological SciencesMonash UniversityClaytonVic.Australia
| | - Joana I. Meier
- Division of Aquatic Ecology and EvolutionInstitute of Ecology and EvolutionUniversity of BernBernSwitzerland
- Department of Fish Ecology and EvolutionCentre of Ecology, Evolution and BiogeochemistryEAWAG Swiss Federal Institute of Aquatic Science and TechnologyKastanienbaumSwitzerland
- Department of ZoologyUniversity of CambridgeCambridgeUK
- St John’s CollegeUniversity of CambridgeCambridgeUK
| | - Salome Mwaiko
- Department of Fish Ecology and EvolutionCentre of Ecology, Evolution and BiogeochemistryEAWAG Swiss Federal Institute of Aquatic Science and TechnologyKastanienbaumSwitzerland
| | - Ole Seehausen
- Division of Aquatic Ecology and EvolutionInstitute of Ecology and EvolutionUniversity of BernBernSwitzerland
- Department of Fish Ecology and EvolutionCentre of Ecology, Evolution and BiogeochemistryEAWAG Swiss Federal Institute of Aquatic Science and TechnologyKastanienbaumSwitzerland
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6
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Arbour JH, Montaña CG, Winemiller KO, Pease AA, Soria-Barreto M, Cochran-Biederman JL, López-Fernández H. Macroevolutionary analyses indicate that repeated adaptive shifts towards predatory diets affect functional diversity in Neotropical cichlids. Biol J Linn Soc Lond 2020. [DOI: 10.1093/biolinnean/blaa001] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Abstract
During adaptive radiation, diversification within clades is limited by adaptation to the available ecological niches, and this may drive patterns of both trait and species diversity. However, adaptation to disparate niches may result in varied impacts on the timing, pattern and rate of morphological evolution. In this study, we examined the relationship between feeding ecology and functional diversification across a diverse clade of freshwater fishes, the Neotropical cichlids. Species dietary niches were ordinated via multivariate analysis of stomach content data. We investigated changes in the rate and pattern of morphological diversification associated with feeding, including dietary niche and degree of dietary specialization. A major division in dietary niche space was observed between predators that consume fish and macroinvertebrates vs. other groups with diets dominated by small invertebrates, detritus or vegetation. These trophic niches were strongly associated with groupings defined by functional morphospace. Clades within the piscivore/macroinvertivore group rarely transitioned to other dietary niches. Comparatively, high dietary specialization enhanced functional diversification, driving the evolution of more extreme morphologies. Divergent patterns of trophic diversification among Neotropical cichlids appear to derive from different performance demands in regional abiotic and biotic environments associated with biogeographical history.
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Affiliation(s)
- Jessica H Arbour
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
- Department of Biology, Middle Tennessee State University, Murfreesboro, TN, USA
| | - Carmen G Montaña
- Department of Biology, Stephen F. Austin State University, Nacogdoches, TX, USA
| | - Kirk O Winemiller
- Department of Wildlife and Fisheries Sciences, Texas A&M University, TAMU, College Station, TX, USA
| | - Allison A Pease
- Department of Natural Resources Management, Texas Tech University, Lubbock, TX, USA
| | - Miriam Soria-Barreto
- Departamento de Conservación de la Biodiversidad, CONACYT - El Colegio de la Frontera Sur (ECOSUR), San Cristóbal de Las Casas, Chiapas, Mexico
- Centro de Investigación de Ciencias Ambientales, Universidad Autónoma del Carmen, Ciudad del Carmen, Campeche, Mexico
| | | | - Hernán López-Fernández
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
- Department of Natural History, Royal Ontario Museum, Toronto, Ontario, Canada
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7
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Selz OM, Seehausen O. Interspecific hybridization can generate functional novelty in cichlid fish. Proc Biol Sci 2019; 286:20191621. [PMID: 31640510 DOI: 10.1098/rspb.2019.1621] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The role of interspecific hybridization in evolution is still being debated. Interspecific hybridization has been suggested to facilitate the evolution of ecological novelty, and hence the invasion of new niches and adaptive radiation when ecological opportunity is present beyond the parental species niches. On the other hand, hybrids between two ecologically divergent species may perform less well than parental species in their respective niches because hybrids would be intermediate in performance in both niches. The evolutionary consequences of hybridization may hence be context-dependent, depending on whether ecological opportunities, beyond those of the parental species, do or do not exist. Surprisingly, these complementary predictions may never have been tested in the same experiment in animals. To do so, we investigate if hybrids between ecologically distinct cichlid species perform less well than the parental species when feeding on food either parent is adapted to, and if the same hybrids perform better than their parents when feeding on food none of the species are adapted to. We generated two first-generation hybrid crosses between species of African cichlids. In feeding efficiency experiments we measured the performance of hybrids and parental species on food types representing both parental species niches and additional 'novel' niches, not used by either of the parental species but by other species in the African cichlid radiations. We found that hybrids can have higher feeding efficiencies on the 'novel' food types but typically have lower efficiencies on parental food types when compared to parental species. This suggests that hybridization can generate functional variation that can be of ecological relevance allowing the access to resources outside of either parental species niche. Hence, we provide support for the hypothesis of ecological context-dependency of the evolutionary impact of interspecific hybridization.
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Affiliation(s)
- O M Selz
- Department of Fish Ecology and Evolution, Center for Ecology, Evolution and Biogeochemistry, EAWAG Swiss Federal Institute of Aquatic Science and Technology, Seestrasse 79, 6047 Kastanienbaum, Switzerland.,Aquatic Ecology and Evolution, Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, 3012 Bern, Switzerland
| | - O Seehausen
- Department of Fish Ecology and Evolution, Center for Ecology, Evolution and Biogeochemistry, EAWAG Swiss Federal Institute of Aquatic Science and Technology, Seestrasse 79, 6047 Kastanienbaum, Switzerland.,Aquatic Ecology and Evolution, Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, 3012 Bern, Switzerland
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8
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Abstract
The tremendous diversity of animal behaviors has inspired generations of scientists from an array of biological disciplines. To complement investigations of ecological and evolutionary factors contributing to behavioral evolution, modern sequencing, gene editing, computational and neuroscience tools now provide a means to discover the proximate mechanisms upon which natural selection acts to generate behavioral diversity. Social behaviors are motivated behaviors that can differ tremendously between closely related species, suggesting phylogenetic plasticity in their underlying biological mechanisms. In addition, convergent evolution has repeatedly given rise to similar forms of social behavior and mating systems in distantly related species. Social behavioral divergence and convergence provides an entry point for understanding the neurogenetic mechanisms contributing to behavioral diversity. We argue that the greatest strides in discovering mechanisms contributing to social behavioral diversity will be achieved through integration of interdisciplinary comparative approaches with modern tools in diverse species systems. We review recent advances and future potential for discovering mechanisms underlying social behavioral variation; highlighting patterns of social behavioral evolution, oxytocin and vasopressin neuropeptide systems, genetic/transcriptional "toolkits," modern experimental tools, and alternative species systems, with particular emphasis on Microtine rodents and Lake Malawi cichlid fishes.
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Affiliation(s)
- Zachary V Johnson
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Larry J Young
- Center for Translational Social Neuroscience, Silvio O. Conte Center for Oxytocin and Social Cognition, Department of Psychiatry and Behavioral Sciences, Yerkes National Primate Research Center, Emory University, Atlanta, Georgia, USA
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9
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Blanke A, Pinheiro M, Watson PJ, Fagan MJ. A biomechanical analysis of prognathous and orthognathous insect head capsules: evidence for a many-to-one mapping of form to function. J Evol Biol 2018; 31:665-674. [PMID: 29444377 DOI: 10.1111/jeb.13251] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 02/06/2018] [Accepted: 02/07/2018] [Indexed: 11/29/2022]
Abstract
Insect head shapes are remarkably variable, but the influences of these changes on biomechanical performance are unclear. Among 'basal' winged insects, such as dragonflies, mayflies, earwigs and stoneflies, some of the most prominent anatomical changes are the general mouthpart orientation, eye size and the connection of the endoskeleton to the head. Here, we assess these variations as well as differing ridge and sclerite configurations using modern engineering methods including multibody dynamics modelling and finite element analysis in order to quantify and compare the influence of anatomical changes on strain in particular head regions and the whole head. We show that a range of peculiar structures such as the genal/subgenal, epistomal and circumocular areas are consistently highly loaded in all species, despite drastically differing morphologies in species with forward-projecting (prognathous) and downward-projecting (orthognathous) mouthparts. Sensitivity analyses show that the presence of eyes has a negligible influence on head capsule strain if a circumocular ridge is present. In contrast, the connection of the dorsal endoskeletal arms to the head capsule especially affects overall head loading in species with downward-projecting mouthparts. Analysis of the relative strains between species for each head region reveals that concerted changes in head substructures such as the subgenal area, the endoskeleton and the epistomal area lead to a consistent relative loading for the whole head capsule and vulnerable structures such as the eyes. It appears that biting-chewing loads are managed by a system of strengthening ridges on the head capsule irrespective of the general mouthpart and head orientation. Concerted changes in ridge and endoskeleton configuration might allow for more radical anatomical changes such as the general mouthpart orientation, which could be an explanation for the variability of this trait among insects. In an evolutionary context, many-to-one mapping of strain patterns onto a relatively similar overall head loading indeed could have fostered the dynamic diversification processes seen in insects.
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Affiliation(s)
- A Blanke
- Institute of Zoology, Biocenter Cologne, University of Cologne, Cologne, Germany.,Medical and Biological Engineering Research Group, School of Engineering and Computer Science, University of Hull, Hull, UK
| | - M Pinheiro
- Medical and Biological Engineering Research Group, School of Engineering and Computer Science, University of Hull, Hull, UK
| | - P J Watson
- Medical and Biological Engineering Research Group, School of Engineering and Computer Science, University of Hull, Hull, UK
| | - M J Fagan
- Medical and Biological Engineering Research Group, School of Engineering and Computer Science, University of Hull, Hull, UK
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10
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Martinez CM, Sparks JS. Malagasy cichlids differentially limit impacts of body shape evolution on oral jaw functional morphology. Evolution 2017. [DOI: 10.1111/evo.13298] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Christopher M. Martinez
- Department of Ichthyology, Division of Vertebrate Zoology American Museum of Natural History New York 10024
- Current address: Department of Evolution and Ecology University of California Davis California 95616
| | - John S. Sparks
- Department of Ichthyology, Division of Vertebrate Zoology American Museum of Natural History New York 10024
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11
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Hu Y, Nelson-Maney N, Anderson PSL. Common evolutionary trends underlie the four-bar linkage systems of sunfish and mantis shrimp. Evolution 2017; 71:1397-1405. [PMID: 28230239 DOI: 10.1111/evo.13208] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Accepted: 02/04/2017] [Indexed: 11/28/2022]
Abstract
Comparative biomechanics offers an opportunity to explore the evolution of disparate biological systems that share common underlying mechanics. Four-bar linkage modeling has been applied to various biological systems such as fish jaws and crustacean appendages to explore the relationship between biomechanics and evolutionary diversification. Mechanical sensitivity states that the functional output of a mechanical system will show differential sensitivity to changes in specific morphological components. We document similar patterns of mechanical sensitivity in two disparate four-bar systems from different phyla: the opercular four-bar system in centrarchid fishes and the raptorial appendage of stomatopods. We built dynamic linkage models of 19 centrarchid and 36 stomatopod species and used phylogenetic generalized least squares regression (PGLS) to compare evolutionary shifts in linkage morphology and mechanical outputs derived from the models. In both systems, the kinematics of the four-bar mechanism show significant evolutionary correlation with the output link, while travel distance of the output arm is correlated with the coupler link. This common evolutionary pattern seen in both fish and crustacean taxa is a potential consequence of the mechanical principles underlying four-bar systems. Our results illustrate the potential influence of physical principles on morphological evolution across biological systems with different structures, behaviors, and ecologies.
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Affiliation(s)
- Yinan Hu
- Department of Biological Sciences, University of Rhode Island, CBLS 440, Kingston, Rhode Island, 02881
| | - Nathan Nelson-Maney
- Department of Biology, University of Massachusetts Amherst, 221 Morrill Science Center, Amherst, Massachusetts, 01003
| | - Philip S L Anderson
- Department of Animal Biology, University of Illinois, Urbana-Champaign, 515 Morrill Hall, Urbana, Illinois, 61801
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12
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Holzman R, Hulsey CD. Mechanical Transgressive Segregation and the Rapid Origin of Trophic Novelty. Sci Rep 2017; 7:40306. [PMID: 28079133 PMCID: PMC5228120 DOI: 10.1038/srep40306] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 12/05/2016] [Indexed: 01/09/2023] Open
Abstract
Hybrid phenotypes are often intermediate between those of parental species. However, hybridization can generate novel phenotypes when traits are complex. For instance, even when the morphologies of individual musculo-skeletal components do not segregate outside the parental range in hybrid offspring, complex functional systems can exhibit emergent phenotypes whose mechanics exceed the parental values. To determine if transgression in mechanics could facilitate divergence during an adaptive radiation, we examined three functional systems in the trophic apparatus of Lake Malawi cichlid fishes. We conducted a simulation study of hybridization between species pairs whose morphology for three functional systems was empirically measured, to determine how the evolutionary divergence of parental species influences the frequency that hybridization could produce mechanics that transgress the parental range. Our simulations suggest that the complex mechanical systems of the cichlid trophic apparatus commonly exhibit greater transgression between more recently diverged cichlid species. Because (1) all three mechanical systems produce hybrids with transgressive mechanics in Lake Malawi cichlids, (2) hybridization is common, and (3) single hybrid crosses often recapitulate a substantial diversity of mechanics, we conclude that mechanical transgressive segregation could play an important role in the rapid accumulation of phenotypic variation in adaptive radiations.
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Affiliation(s)
- Roi Holzman
- Department of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
- The Inter-University Institute for Marine Sciences, POB 469, Eilat 88103, Israel
| | - C. Darrin Hulsey
- Department of Biological Sciences, University of Konstanz, Konstanz, 78457, Germany
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13
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Anderson PSL, Patek SN. Mechanical sensitivity reveals evolutionary dynamics of mechanical systems. Proc Biol Sci 2015; 282:20143088. [PMID: 25716791 DOI: 10.1098/rspb.2014.3088] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
A classic question in evolutionary biology is how form-function relationships promote or limit diversification. Mechanical metrics, such as kinematic transmission (KT) in linkage systems, are useful tools for examining the evolution of form and function in a comparative context. The convergence of disparate systems on equivalent metric values (mechanical equivalence) has been highlighted as a source of potential morphological diversity under the assumption that morphology can evolve with minimal impact on function. However, this assumption does not account for mechanical sensitivity-the sensitivity of the metric to morphological changes in individual components of a structure. We examined the diversification of a four-bar linkage system in mantis shrimp (Stomatopoda), and found evidence for both mechanical equivalence and differential mechanical sensitivity. KT exhibited variable correlations with individual linkage components, highlighting the components that influence KT evolution, and the components that are free to evolve independently from KT and thereby contribute to the observed pattern of mechanical equivalence. Determining the mechanical sensitivity in a system leads to a deeper understanding of both functional convergence and morphological diversification. This study illustrates the importance of multi-level analyses in delineating the factors that limit and promote diversification in form-function systems.
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Affiliation(s)
- P S L Anderson
- Department of Biology, Duke University, Box 90338, Durham, NC 27708, USA
| | - S N Patek
- Department of Biology, Duke University, Box 90338, Durham, NC 27708, USA
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14
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Hochberg R, Wallace RL, Walsh EJ. Soft Bodies, Hard Jaws: An Introduction to the Symposium, with Rotifers as Models of Jaw Diversity. Integr Comp Biol 2015; 55:179-92. [PMID: 25796591 PMCID: PMC6296403 DOI: 10.1093/icb/icv002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Jaws have evolved numerous times in the animal kingdom and they display a wide variety of structural, compositional, and functional characteristics that reflect their polyphyletic origins. Among soft-bodied invertebrates, jaws are known from annelids, chaetognaths, flatworms, gnathostomulids, micrognathozoans, mollusks, rotifers, and several ecdysozoans. Depending on the taxon, jaws may function in the capture of prey (e.g., chaetognaths and flatworms), processing of prey (e.g., gnathostomulids and onychophorans), or both (e.g., rotifers). Although structural diversity among invertebrates’ jaws is becoming better characterized with the use of electron microscopy, many details remain poorly described, including neuromuscular control, elemental composition, and physical characteristics, such as hardness and resistance to wear. Unfortunately, absence of relevant data has impeded understanding of their functional diversity and evolutionary origins. With this symposium, we bring together researchers of disparately jawed taxa to draw structural and mechanistic comparisons among species to determine their commonalities. Additionally, we show that rotifers’ jaws, which are perhaps the best-characterized jaws among invertebrates, are still enigmatic with regard to their origins and mechanics. Nevertheless, technologies such as energy dispersive X-ray spectroscopy (EDX) and 3D modeling are being used to characterize their chemical composition and to develop physical models that allow exploration of their mechanical properties, respectively. We predict that these methods can also be used to develop biomimetic and bioinspired constructs based on the full range of the complexity of jaws, and that such constructs also can be developed from other invertebrate taxa. These approaches may also shed light on common developmental and physiological processes that facilitate the evolution of invertebrates’ jaws.
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Affiliation(s)
- Rick Hochberg
- *Department of Biology, University of Massachusetts Lowell, One University Avenue, Lowell, MA 01854, USA
| | - Robert L. Wallace
- Biology Department, Ripon College, 300 Seward Street, Ripon, WI 54971, USA
| | - Elizabeth J. Walsh
- Department of Biological Sciences, University of Texas at El Paso, El Paso, TX 79968, USA
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York RA, Patil C, Hulsey CD, Streelman JT, Fernald RD. Evolution of bower building in Lake Malawi cichlid fish: phylogeny, morphology, and behavior. Front Ecol Evol 2015. [DOI: 10.3389/fevo.2015.00018] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
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Abstract
The extraordinary species richness of freshwater fishes has attracted much research on mechanisms and modes of speciation. We here review research on speciation in freshwater fishes in light of speciation theory, and place this in a context of broad-scale diversity patterns in freshwater fishes. We discuss several major repeated themes in freshwater fish speciation and the speciation mechanisms they are frequently associated with. These include transitions between marine and freshwater habitats, transitions between discrete freshwater habitats, and ecological transitions within habitats, as well as speciation without distinct niche shifts. Major research directions in the years to come include understanding the transition from extrinsic environment-dependent to intrinsic reproductive isolation and its influences on species persistence and understanding the extrinsic and intrinsic constraints to speciation and how these relate to broad-scale diversification patterns through time.
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Affiliation(s)
- Ole Seehausen
- Division of Aquatic Ecology and Evolution, Institute of Ecology and Evolution, University of Bern, CH-3012 Bern, Switzerland
- Department of Fish Ecology and Evolution, EAWAG Swiss Federal Institute of Aquatic Science and Technology, Center of Ecology, Evolution and Biogeochemistry, 6047 Kastanienbaum, Switzerland
| | - Catherine E. Wagner
- Division of Aquatic Ecology and Evolution, Institute of Ecology and Evolution, University of Bern, CH-3012 Bern, Switzerland
- Department of Fish Ecology and Evolution, EAWAG Swiss Federal Institute of Aquatic Science and Technology, Center of Ecology, Evolution and Biogeochemistry, 6047 Kastanienbaum, Switzerland
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17
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Rupp MF, Hulsey CD. Influence of substrate orientation on feeding kinematics and performance of algae grazing Lake Malawi cichlid fishes. J Exp Biol 2014; 217:3057-66. [DOI: 10.1242/jeb.105080] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Abstract
Lake Malawi cichlids have been studied extensively in an effort to elucidate the mechanisms underlying their adaptive radiation. Both habitat partitioning and trophic specialization have been suggested to be critical ecological axes underlying the exceptional diversification of these fishes, but the mechanisms facilitating this divergence are often unclear. For instance, in the rock-dwelling mbuna of Lake Malawi, coexistence is likely tightly linked to how and where species feed on the algae coating all the surfaces of the rocky reefs they exclusively inhabit. Yet, although mbuna species often preferentially graze from particular substrate orientations, we understand very little about how substrate orientation influences feeding kinematics or feeding rates in any group of organisms. Therefore, for three species of mbuna, we quantified feeding kinematics and inferred the rates that algae could be ingested on substrates that mimicked the top, sides, and bottoms of the algae covered boulders these species utilize in Lake Malawi. A number of differences in feeding kinematics were found among species, and several of the kinematic variables were found to differ even within species when the fish grazed from different surface orientations. However, despite their preferences for particular microhabitats, we found no evidence for clear tradeoffs in the rates that the three species were inferred to be able to obtain algae from different substrate orientations. Nevertheless, our results indicate microhabitat divergence linked to differences in feeding kinematics could have played a role in the origin and maintenance of the vast diversity of co-occurring Lake Malawi mbuna species.
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Selz OM, Lucek K, Young KA, Seehausen O. Relaxed trait covariance in interspecific cichlid hybrids predicts morphological diversity in adaptive radiations. J Evol Biol 2013; 27:11-24. [DOI: 10.1111/jeb.12283] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Accepted: 09/27/2013] [Indexed: 01/29/2023]
Affiliation(s)
- O. M. Selz
- Department of Fish Ecology and Evolution; EAWAG Swiss Federal Institute of Aquatic Science and Technology; Center for Ecology, Evolution and Biogeochemistry; Kastanienbaum Switzerland
- Division of Aquatic Ecology and Evolution; Institute of Ecology and Evolution; University of Bern; Bern Switzerland
| | - K. Lucek
- Department of Fish Ecology and Evolution; EAWAG Swiss Federal Institute of Aquatic Science and Technology; Center for Ecology, Evolution and Biogeochemistry; Kastanienbaum Switzerland
- Division of Aquatic Ecology and Evolution; Institute of Ecology and Evolution; University of Bern; Bern Switzerland
| | | | - O. Seehausen
- Division of Aquatic Ecology and Evolution; Institute of Ecology and Evolution; University of Bern; Bern Switzerland
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Genetic interactions controlling sex and color establish the potential for sexual conflict in Lake Malawi cichlid fishes. Heredity (Edinb) 2012; 110:239-46. [PMID: 23092997 DOI: 10.1038/hdy.2012.73] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Sex-determining systems may evolve rapidly and contribute to lineage diversification. In fact, recent work has suggested an integral role of sex chromosome evolution in models of speciation. We use quantitative trait loci analysis of restriction site-associated DNA -tag single nucleotide polymorphisms to identify multiple loci responsible for sex determination and reproductively adaptive color phenotypes in Lake Malawi cichlids. We detect a complex epistatic sex system consisting of a major female heterogametic ZW locus on chromosome 5, two separate male heterogametic XY loci on chromosome 7, and two additional interacting loci on chromosomes 3 and 20. Our data support the known chromosomal linkage between orange blotch color and ZW, as well as novel genetic associations between male blue nuptial color and two sex determining regions (an XY and ZW locus). These results provide further empirical evidence for a complex antagonistic sex-color system in this species flock and suggest a possible role for, and effect of, polygenic sex-determining systems in rapid evolutionary diversification.
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Culumber ZW, Shepard DB, Coleman SW, Rosenthal GG, Tobler M. Physiological adaptation along environmental gradients and replicated hybrid zone structure in swordtails (Teleostei: Xiphophorus). J Evol Biol 2012; 25:1800-14. [PMID: 22827312 DOI: 10.1111/j.1420-9101.2012.02562.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Local adaptation is often invoked to explain hybrid zone structure, but empirical evidence of this is generally rare. Hybrid zones between two poeciliid fishes, Xiphophorus birchmanni and X. malinche, occur in multiple tributaries with independent replication of upstream-to-downstream gradients in morphology and allele frequencies. Ecological niche modelling revealed that temperature is a central predictive factor in the spatial distribution of pure parental species and their hybrids and explains spatial and temporal variation in the frequency of neutral genetic markers in hybrid populations. Among populations of parentals and hybrids, both thermal tolerance and heat-shock protein expression vary strongly, indicating that spatial and temporal structure is likely driven by adaptation to local thermal environments. Therefore, hybrid zone structure is strongly influenced by interspecific differences in physiological mechanisms for coping with the thermal environment.
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Affiliation(s)
- Z W Culumber
- Department of Biology, Texas A&M University, TAMU, College Station, TX 77840, USA.
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Abstract
The relationship between form and function can have profound effects on evolutionary dynamics and such effects may differ for simple versus complex systems. In particular, functions produced by multiple structural configurations (many-to-one mapping, MTOM) may dampen constituent trade-offs and promote diversification. Unfortunately, we lack information about the genetic architecture of MTOM functional systems. The skulls of teleost fishes contain both simple (lower jaw levers) as well as more complex (jaws modeled as 4-bar linkages) functional systems within the same craniofacial unit. We examined the mapping of form to function and the genetic basis of these systems by identifying quantitative trait loci (QTL) in hybrids of two Lake Malawi cichlid species. Hybrid individuals exhibited novelty (transgressive segregation) in morphological components and function of the simple and complex jaw systems. Functional novelty was proportional to the prevalence of extreme morphologies in the simple levers; by contrast, recombination of parental morphologies produced transgression in the MTOM 4-bar linkage. We found multiple loci of moderate effect and epistasis controlling jaw phenotypes in both the simple and complex systems, with less phenotypic variance explained by QTL for the 4-bar. Genetic linkage between components of the simple and complex systems partly explains phenotypic correlations and may constrain functional evolution.
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Affiliation(s)
- Nicholas F Parnell
- School of Biology, Institute of Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.
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Tkint T, Verheyen E, De Kegel B, Helsen P, Adriaens D. Dealing with food and eggs in mouthbrooding cichlids: structural and functional trade-offs in fitness related traits. PLoS One 2012; 7:e31117. [PMID: 22348043 PMCID: PMC3279513 DOI: 10.1371/journal.pone.0031117] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2011] [Accepted: 01/03/2012] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND As in any vertebrate, heads of fishes are densely packed with functions. These functions often impose conflicting mechanical demands resulting in trade-offs in the species-specific phenotype. When phenotypical traits are linked to gender-specific parental behavior, we expect sexual differences in these trade-offs. This study aims to use mouthbrooding cichlids as an example to test hypotheses on evolutionary trade-offs between intricately linked traits that affect different aspects of fitness. We focused on the oral apparatus, which is not only equipped with features used to feed and breathe, but is also used for the incubation of eggs. We used this approach to study mouthbrooding as part of an integrated functional system with diverging performance requirements and to explore gender-specific selective environments within a species. METHODOLOGY/PRINCIPAL FINDINGS Because cichlids are morphologically very diverse, we hypothesize that the implications of the added constraint of mouthbrooding will primarily depend on the dominant mode of feeding of the studied species. To test this, we compared the trade-off for two maternal mouthbrooding cichlid species: a "suction feeder" (Haplochromis piceatus) and a "biter" (H. fischeri). The comparison of morphology and performance of both species revealed clear interspecific and intersex differences. Our observation that females have larger heads was interpreted as a possible consequence of the fact that in both the studied species mouthbrooding is done by females only. As hypothesized, the observed sexual dimorphism in head shape is inferred as being suboptimal for some aspects of the feeding performance in each of the studied species. Our comparison also demonstrated that the suction feeding species had smaller egg clutches and more elongated eggs. CONCLUSIONS/SIGNIFICANCE Our findings support the hypothesis that there is a trade-off between mouthbrooding and feeding performance in the two studied haplochromine cichlids, stressing the importance of including species-specific information at the gender level when addressing interspecific functional/morphological differences.
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Affiliation(s)
- Tim Tkint
- Department of Biology, Research Group Evolutionary Morphology of Vertebrates, Ghent University, Ghent, Belgium.
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Konow N, Bellwood DR. Evolution of high trophic diversity based on limited functional disparity in the feeding apparatus of marine angelfishes (f. Pomacanthidae). PLoS One 2011; 6:e24113. [PMID: 21909414 PMCID: PMC3164712 DOI: 10.1371/journal.pone.0024113] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Accepted: 07/31/2011] [Indexed: 11/18/2022] Open
Abstract
The use of biting to obtain food items attached to the substratum is an ecologically widespread and important mode of feeding among aquatic vertebrates, which rarely has been studied. We did the first evolutionary analyses of morphology and motion kinematics of the feeding apparatus in Indo-Pacific members of an iconic family of biters, the marine angelfishes (f. Pomacanthidae). We found clear interspecific differences in gut morphology that clearly reflected a wide range of trophic niches. In contrast, feeding apparatus morphology appeared to be conserved. A few unusual structural innovations enabled angelfishes to protrude their jaws, close them in the protruded state, and tear food items from the substratum at a high velocity. Only one clade, the speciose pygmy angelfishes, showed functional departure from the generalized and clade-defining grab-and-tearing feeding pattern. By comparing the feeding kinematics of angelfishes with wrasses and parrotfishes (f. Labridae) we showed that grab-and-tearing is based on low kinematics disparity. Regardless of its restricted disparity, the grab-and-tearing feeding apparatus has enabled angelfishes to negotiate ecological thresholds: Given their widely different body sizes, angelfishes can access many structurally complex benthic surfaces that other biters likely are unable to exploit. From these surfaces, angelfishes can dislodge sturdy food items from their tough attachments. Angelfishes thus provide an intriguing example of a successful group that appears to have evolved considerable trophic diversity based on an unusual yet conserved feeding apparatus configuration that is characterized by limited functional disparity.
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Affiliation(s)
- Nicolai Konow
- School of Marine and Tropical Biology, and Australian Research Council Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Australia.
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PFAENDER J, MIESEN FW, HADIATY RK, HERDER F. Adaptive speciation and sexual dimorphism contribute to diversity in form and function in the adaptive radiation of Lake Matano’s sympatric roundfin sailfin silversides. J Evol Biol 2011; 24:2329-45. [DOI: 10.1111/j.1420-9101.2011.02357.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Abstract
A long-standing debate in ecology addresses whether community composition is the result of stochastic factors or assembly rules. Non-random, over-dispersed patterns of species co-occurrence have commonly been attributed to competition--a particularly important force in adaptive radiation. We thus examined the macroecology of the recently radiated cichlid rock-fish assemblage in Lake Malawi, Africa at a spectrum of increasingly fine spatial scales (entire lake to depth within rock-reef sites). Along this range of spatial scales, we observed a signal of community structure (decreased co-occurrence of species) at the largest and smallest scales, but not in between. Evidence suggests that the lakewide signature of structure is driven by extreme endemism and micro-allopatric speciation, while patterns of reduced co-occurrence with depth are indicative of species interactions. We identified a 'core' set of rock-reef species, found in combination throughout the lake, whose depth profiles exhibited replicated positive and negative correlation. Our results provide insight into how ecological communities may be structured differently at distinct spatial scales, re-emphasize the importance of local species interactions in community assembly, and further elucidate the processes shaping speciation in this model adaptive radiation.
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Affiliation(s)
- Nicholas F Parnell
- Department of Biology, Georgia Institute of Technology, Atlanta, GA 30332, USA.
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MIKULA ONDREJ, AUFFRAY JEANCHRISTOPHE, MACHOLAN MILOS. Asymmetric size and shape variation in the Central European transect across the house mouse hybrid zone. Biol J Linn Soc Lond 2010. [DOI: 10.1111/j.1095-8312.2010.01490.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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TOBLER M, CARSON EW. Environmental variation, hybridization, and phenotypic diversification in Cuatro Ciénegas pupfishes. J Evol Biol 2010; 23:1475-89. [DOI: 10.1111/j.1420-9101.2010.02014.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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MIMS MERYLC, DARRIN HULSEY C, FITZPATRICK BENJAMINM, TODD STREELMAN J. Geography disentangles introgression from ancestral polymorphism in Lake Malawi cichlids. Mol Ecol 2010; 19:940-51. [DOI: 10.1111/j.1365-294x.2010.04529.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Stelkens RB, Schmid C, Selz O, Seehausen O. Phenotypic novelty in experimental hybrids is predicted by the genetic distance between species of cichlid fish. BMC Evol Biol 2009; 9:283. [PMID: 19961584 PMCID: PMC2796671 DOI: 10.1186/1471-2148-9-283] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2009] [Accepted: 12/04/2009] [Indexed: 11/20/2022] Open
Abstract
Background Transgressive segregation describes the occurrence of novel phenotypes in hybrids with extreme trait values not observed in either parental species. A previously experimentally untested prediction is that the amount of transgression increases with the genetic distance between hybridizing species. This follows from QTL studies suggesting that transgression is most commonly due to complementary gene action or epistasis, which become more frequent at larger genetic distances. This is because the number of QTLs fixed for alleles with opposing signs in different species should increase with time since speciation provided that speciation is not driven by disruptive selection. We measured the amount of transgression occurring in hybrids of cichlid fish bred from species pairs with gradually increasing genetic distances and varying phenotypic similarity. Transgression in multi-trait shape phenotypes was quantified using landmark-based geometric morphometric methods. Results We found that genetic distance explained 52% and 78% of the variation in transgression frequency in F1 and F2 hybrids, respectively. Confirming theoretical predictions, transgression when measured in F2 hybrids, increased linearly with genetic distance between hybridizing species. Phenotypic similarity of species on the other hand was not related to the amount of transgression. Conclusion The commonness and ease with which novel phenotypes are produced in cichlid hybrids between unrelated species has important implications for the interaction of hybridization with adaptation and speciation. Hybridization may generate new genotypes with adaptive potential that did not reside as standing genetic variation in either parental population, potentially enhancing a population's responsiveness to selection. Our results make it conceivable that hybridization contributed to the rapid rates of phenotypic evolution in the large and rapid adaptive radiations of haplochromine cichlids.
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Affiliation(s)
- Rike B Stelkens
- Institute of Ecology and Evolution, University of Bern, Switzerland.
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SALZBURGER WALTER. The interaction of sexually and naturally selected traits in the adaptive radiations of cichlid fishes. Mol Ecol 2009; 18:169-85. [DOI: 10.1111/j.1365-294x.2008.03981.x] [Citation(s) in RCA: 193] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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