Sensory convergence in the world s largest cavefish diversification: patterns of neuromast evolution, distribution and associated behaviour in Sinocyclocheilus

Sinocyclocheilus represents the largest freshwater cavefish genus in the world. This emerging model system is endemic to the southern Chinese karstic landscape, and demonstrates multiple adaptations for life in caves (troglomorphism), with eye-degeneration being the most pronounced. The less-apparent lateral line system, which is often expanded in cave-dwellers, has been studied in other cavefish systems, but never in the context of this diversification. Here we investigated the distribution and evolution of cephalic neuromasts in 26 Sinocyclocheilus species. We used live-staining and behavioural assays, and interpreted results in a phylogenetic context. We show that asymmetry in neuromast features and the rate of evolution is greater in cave-adapted species. Ancestral state reconstructions show that most Sinocyclocheilus are right-biased with some scatter, and show convergence of neuromast phenotypes. There is substantial variation in cephalic neuromast distribution patterns between and (to a lesser extent) within species. Behavioural assays show blind species have a distinctive wall-following behaviour. We explain these patterns in the context of the deep evolutionary history associated with this karstic region, other traits, and habitat occupation of these remarkable diversifications of fishes. Interestingly, some of these neuromast patterns and behaviour show convergence with other phylogenetically distant cavefish systems.

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Ultrastructure of superficial neuromasts in the mottled sculpin, Cottus bairdi

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100156778 ◽

1989 ◽

Vol 47 ◽

pp. 958-959

Author(s):

W.R. Jones ◽

S. Coombs ◽

J. Janssen

Keyword(s):

Hair Cells ◽

Lateral Line System ◽

Electron Microscopic ◽

Line System ◽

Dense Cores ◽

Sensory Hair Cells ◽

Cytoplasmic Vesicles ◽

Cottus Bairdi ◽

Mottled Sculpin ◽

Upper Third

The lateral line system of the mottled sculpin, like that of most bony fish, has both canal (CNM) and superficial (SNM) sensory end organs, neuromasts, which are distributed on the head and trunk in discrete, readily identifiable groupings (Fig. 1). CNM and SNM differ grossly in location and in overall size and shape. The former are located in subdermal canals and are larger and asymmetric in shape, The latter are located directly on the surface of the skin and are much smaller and more symmetrical It has been suggested that the two may differ at a more fundamental level in such functionally related parameters as extent of myelination of innervating fibers and the absence of efferent innervation in SNM. The present study addresses the validity of these last two features as distinguishing criteria by examining the structure of those SNM populations indicated in Fig. 1 at both the light and electron microscopic levels.All of the populations of SNM examined conform in general to previously published descriptions, consisting of a neuroepithelium composed of sensory hair cells, support cells and mantle cells, Several significant differences from these accounts have, however, emerged. Firstly, the structural composition of the innervating fibers is heterogeneous with respect to the extent of myelination. All SNM groups, with the possible exception of the TRrs and CFLs, possess both myelinated and unmyelinated fibers within the neuroepithelium proper (Fig. 2), just as do CNM. The extent of myelina- tion is quite variable, with some fibers sheath terminating just before crossing the neuroepithelial basal lamina, some just after and a few retaining their myelination all the way to the base of the hair cells in the upper third of the neuroepithelium. Secondly, all SNMs possess fibers that may, on the basis of ultrastructural criteria, be identified as efferent. Such fibers contained numerous cytoplasmic vesicles, both clear and with dense cores. In regions where such fibers closely apposed hair cells, subsynaptic cisternae were observed in the hair cell (Fig. 3).

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Lateral line system

AccessScience ◽

10.1036/1097-8542.757316 ◽

2015 ◽

Keyword(s):

Lateral Line ◽

Lateral Line System ◽

Line System

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A new species of Ampulicomorpha Ashmead from Eocene French amber, with a list of fossil and extant Embolemidae (Insecta: Hymenoptera) of the world

BSGF - Earth Sciences Bulletin ◽

10.1051/bsgf/2020020 ◽

2020 ◽

Vol 191 ◽

pp. 20

Author(s):

Cédric Chény ◽

Elvis Guillam ◽

André Nel ◽

Vincent Perrichot

Keyword(s):

New Species ◽

Evolutionary History ◽

Western Europe ◽

Distribution Map ◽

Single Female ◽

Fossil Species ◽

The World ◽

Poor Group ◽

A New Species ◽

Eocene Amber

Embolemidae is a cosmopolitan but species-poor group of chrysidoid wasps with a scarce fossil record, despite a long evolutionary history since at least the Early Cretaceous. Here, the new species, Ampulicomorpha quesnoyensis sp. nov., is illustrated and described based on a single female found in Early Eocene amber of Oise (France). The new species is compared with the three other known fossil species of the genus, and a key to all fossil species of Ampulicomorpha is provided. This is the third European fossil species of Ampulicomorpha, which suggests that the genus was once well established in Western Europe while it is more widely distributed in the Eastern Palaearctic region today. A list of all fossil and extant Embolemidae of the world, as well as a map of their geographical distribution map, are provided.

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Constraints on the ecomorphological convergence of zooplanktivorous butterflyfishes

Integrative Organismal Biology ◽

10.1093/iob/obab014 ◽

2021 ◽

Author(s):

Jennifer R Hodge ◽

Yutong Song ◽

Molly A Wightman ◽

Analisa Milkey ◽

Binh Tran ◽

...

Keyword(s):

Evolutionary History ◽

Swimming Performance ◽

Morphological Evolution ◽

Distinct Type ◽

Ancestral State ◽

Multiple Traits ◽

Visual Identification ◽

Form Function ◽

Morphological Distinction ◽

Foraging Modes

Abstract Whether distantly related organisms evolve similar strategies to meet the demands of a shared ecological niche depends on their evolutionary history and the nature of form-function relationships. In fishes, the visual identification and consumption of microscopic zooplankters, selective zooplanktivory, is a distinct type of foraging often associated with a suite of morphological specialisations. Previous work has identified inconsistencies in the trajectory and magnitude of morphological change following transitions to selective zooplanktivory, alluding to the diversity and importance of ancestral effects. Here we investigate whether transitions to selective zooplanktivory have influenced the morphological evolution of marine butterflyfishes (family Chaetodontidae), a group of small-prey specialists well known for several types of high-precision benthivory. Using Bayesian ancestral state estimation, we inferred the recent evolution of zooplanktivory among benthivorous ancestors that hunted small invertebrates and browsed by picking or scraping coral polyps. Traits related to the capture of prey appear to be functionally versatile with little morphological distinction between species with benthivorous and planktivorous foraging modes. In contrast, multiple traits related to prey detection or swimming performance are evolving toward novel, zooplanktivore-specific optima. Despite a relatively short evolutionary history, general morphological indistinctiveness, and evidence of constraint on the evolution of body size, convergent evolution has closed a near significant amount of the morphological distance between zooplanktivorous species. Overall, our findings describe the extent to which the functional demands associated with selective zooplanktivory have led to generalisable morphological features among butterflyfishes and highlight the importance of ancestral effects in shaping patterns of morphological convergence.

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The lateral line system and its innervation in the Japanese eel Anguilla japonica (Teleostei: Elopomorpha: Anguillidae)

Journal of Morphology ◽

10.1002/jmor.21353 ◽

2021 ◽

Author(s):

Masanori Nakae ◽

Mari Kuroki ◽

Mao Sato ◽

Kunio Sasaki

Keyword(s):

Lateral Line ◽

Anguilla Japonica ◽

Japanese Eel ◽

Lateral Line System ◽

Line System

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Frequency response properties of primary afferent neurons in the posterior lateral line system of larval zebrafish

Journal of Neurophysiology ◽

10.1152/jn.00414.2014 ◽

2015 ◽

Vol 113 (2) ◽

pp. 657-668 ◽

Cited By ~ 9

Author(s):

Rafael Levi ◽

Otar Akanyeti ◽

Aleksander Ballo ◽

James C. Liao

Keyword(s):

Lateral Line ◽

Sine Wave ◽

Afferent Neuron ◽

Lateral Line System ◽

Afferent Neurons ◽

Primary Afferent Neurons ◽

Primary Afferent ◽

Line System ◽

Response Properties ◽

Larval Zebrafish

The ability of fishes to detect water flow with the neuromasts of their lateral line system depends on the physiology of afferent neurons as well as the hydrodynamic environment. Using larval zebrafish ( Danio rerio), we measured the basic response properties of primary afferent neurons to mechanical deflections of individual superficial neuromasts. We used two types of stimulation protocols. First, we used sine wave stimulation to characterize the response properties of the afferent neurons. The average frequency-response curve was flat across stimulation frequencies between 0 and 100 Hz, matching the filtering properties of a displacement detector. Spike rate increased asymptotically with frequency, and phase locking was maximal between 10 and 60 Hz. Second, we used pulse train stimulation to analyze the maximum spike rate capabilities. We found that afferent neurons could generate up to 80 spikes/s and could follow a pulse train stimulation rate of up to 40 pulses/s in a reliable and precise manner. Both sine wave and pulse stimulation protocols indicate that an afferent neuron can maintain their evoked activity for longer durations at low stimulation frequencies than at high frequencies. We found one type of afferent neuron based on spontaneous activity patterns and discovered a correlation between the level of spontaneous and evoked activity. Overall, our results establish the baseline response properties of lateral line primary afferent neurons in larval zebrafish, which is a crucial step in understanding how vertebrate mechanoreceptive systems sense and subsequently process information from the environment.

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Diversity and sexual dimorphism in the head lateral line system in North Sea populations of threespine sticklebacks, Gasterosteus aculeatus (Teleostei: Gasterosteidae)

Zoomorphology ◽

10.1007/s00435-020-00513-1 ◽

2020 ◽

Author(s):

Harald Ahnelt ◽

David Ramler ◽

Maria Ø. Madsen ◽

Lasse F. Jensen ◽

Sonja Windhager

Keyword(s):

Sexual Dimorphism ◽

North Sea ◽

Lateral Line ◽

Gasterosteus Aculeatus ◽

Sensory System ◽

Threespine Stickleback ◽

Lateral Line System ◽

Line System ◽

Marine Population ◽

Threespine Sticklebacks

AbstractThe mechanosensory lateral line of fishes is a flow sensing system and supports a number of behaviors, e.g. prey detection, schooling or position holding in water currents. Differences in the neuromast pattern of this sensory system reflect adaptation to divergent ecological constraints. The threespine stickleback, Gasterosteus aculeatus, is known for its ecological plasticity resulting in three major ecotypes, a marine type, a migrating anadromous type and a resident freshwater type. We provide the first comparative study of the pattern of the head lateral line system of North Sea populations representing these three ecotypes including a brackish spawning population. We found no distinct difference in the pattern of the head lateral line system between the three ecotypes but significant differences in neuromast numbers. The anadromous and the brackish populations had distinctly less neuromasts than their freshwater and marine conspecifics. This difference in neuromast number between marine and anadromous threespine stickleback points to differences in swimming behavior. We also found sexual dimorphism in neuromast number with males having more neuromasts than females in the anadromous, brackish and the freshwater populations. But no such dimorphism occurred in the marine population. Our results suggest that the head lateral line of the three ecotypes is under divergent hydrodynamic constraints. Additionally, sexual dimorphism points to divergent niche partitioning of males and females in the anadromous and freshwater but not in the marine populations. Our findings imply careful sampling as an important prerequisite to discern especially between anadromous and marine threespine sticklebacks.

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