Latest Articles from Subterranean Biology Latest 13 Articles from Subterranean Biology https://subtbiol.pensoft.net/ Fri, 29 Mar 2024 17:40:52 +0200 Pensoft FeedCreator https://subtbiol.pensoft.net/i/logo.jpg Latest Articles from Subterranean Biology https://subtbiol.pensoft.net/ The first record of a stygobiotic form of Garra rufa (Heckel, 1843), sympatric with Garra tashanensis Mousavi-Sabet, Vatandoust, Fatemi & Eagderi, 2016 (Teleostei, Cyprinidae), in Iranian subterranean waters https://subtbiol.pensoft.net/article/108396/ Subterranean Biology 46: 97-127

DOI: 10.3897/subtbiol.46.108396

Authors: Mohammad Javad Malek-Hosseini, Jean-François Flot, Yaser Fatemi, Hamid Babolimoakher, Matjaž Kuntner, Oleg A. Diripasko, Dušan Jelić, Nina G. Bogutskaya

Abstract: We report the first finding of the stygobiotic form of the cyprinid fish Garra rufa (Heckel, 1843), discovered in a single locality in southwestern Iran, while the epigean form of the species is widely distributed in western Asia (Iran, Jordan, Lebanon, Turkey, and Syria). We also report a new locality for its hypogean congener, Garra tashanensis, about 5 km east of its type locality. The two species occur in syntopy in outflows of the Tang-e-Ban, a seasonal karstic spring that only has flowing water during winter and spring, when fish individuals are washed from the cave to the surface. Identification of the investigated samples was confirmed by morphological analyses, COI distances, and a phylogenetic tree. These findings suggest the existence of a large karst aquifer in the Tashan area that harbours several cave species of fish, crustaceans, and gastropods and may have considerable conservation implications.

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Research Article Tue, 17 Oct 2023 15:24:56 +0300
New records of cave-dwelling populations of Rhamdia catfishes (Siluriformes, Heptapteridae) from Chiapas, Mexico https://subtbiol.pensoft.net/article/110269/ Subterranean Biology 46: 61-76

DOI: 10.3897/subtbiol.46.110269

Authors: Martín Alonso Buenavad-González, Jesús M. López-Vila, David Torres-Vázquez, Sonia Gabriela Hernández-Ávila, Kaleb Zárate-Gálvez, Jairo Arroyave

Abstract: Dedicated ichthyological surveys in four active karstic caves in the Mexican state of Chiapas (Grijalva River drainage basin) resulted in the discovery of the same number of hypogean populations of Rhamdia catfishes assignable to two different species: R. laticauda and R. guatemalensis. The taxonomic identity of these populations was initially determined based on morphological traits and subsequently corroborated with molecular data in a phylogenetic framework. For the most part, these newly discovered populations exhibit partial and variable troglomorphism (vs. fixed), a pattern that has been observed in most other cave-dwelling species/populations of Mexican Rhamdia, and possibly caused by gene flow with and/or incipient speciation from epigean lineages. Since most hypogean forms of Mexican Rhamdia derive from/are part of a larger R. laticauda clade, our discovery of cave-dwelling populations assignable to R. guatemalensis is noteworthy and includes the very first record of a R. guatemalensis population with pronounced and widespread troglomorphism. Our discovery of hitherto unrecorded populations of hypogean Rhamdia highlights the continued importance of exploration in the process of documenting subterranean biodiversity, particularly in regions of the world rich with cave systems. Our findings corroborate the notion that, among Neotropical fishes, the catfish genus Rhamdia is one of the most prone and effective at colonizing subterranean habitats and establishing viable hypogean populations.

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Research Article Tue, 19 Sep 2023 16:25:46 +0300
Protocol for lens removal in embryonic fish and its application on the developmental effects of eye regression https://subtbiol.pensoft.net/article/96963/ Subterranean Biology 45: 39-52

DOI: 10.3897/subtbiol.45.96963

Authors: Luis Espinasa, Marie Pavie, Sylvie Rétaux

Abstract: The lens plays a central role in the development of the optic cup. In fish, regression of the eye early in development affects the development of the craniofacial skeleton, the size of the olfactory pits, the optic nerve, and the tectum. Lens removal further affects olfaction, prey capture, and aggression. The similarity of the fish eye to other vertebrates is the basis for its use as an excellent animal model of human defects. Questions regarding the effects of eye regression are specifically well-suited to be addressed by using fish from the genus Astyanax. The species has two morphs; an eyeless cave morph and an eyed, surface morph. In the cavefish, a lens initially develops in embryos, but then degenerates by apoptosis. The cavefish retina is subsequently disorganized, degenerates, and retinal growth is arrested. The same effect is observed in surface fish when the lens is removed or exchanged for a cavefish lens. While studies can greatly benefit from a control group of surface fish with regressed eyes brought through lensectomies, few studies include them because of technical difficulties and the low survivorship of embryos that undergo this procedure. Here we describe a technique with significant modification for improvement for conducting lensectomy in one-day-old Astyanax and other fish, including zebrafish. Yields of up to 30 live embryos were obtained using this technique from a single spawn, thus enabling studies that require large sample sizes.

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Research Article Thu, 2 Feb 2023 14:40:41 +0200
Laterality in cavefish: Left or right foraging behavior in Astyanax mexicanus https://subtbiol.pensoft.net/article/86565/ Subterranean Biology 44: 123-138

DOI: 10.3897/subtbiol.44.86565

Authors: Luis Espinasa, Ruth Diamant, Marylena Mesquita, Julianna M. Lindquist, Adrianna M. Powers, James Helmreich

Abstract: The evolution of foraging behaviors is key to colonizing challenging habitats such as a cave’s dark environment. Vibration attraction behavior (VAB) gives fish the ability to swim in the darkness toward a vibration stimulus produced by many prey crustaceans and insects. VAB evolved in the blind Mexican cave tetra, Astyanax mexicanus. VAB is regulated by an increased number of mechanosensory neuromasts, particularly in the eye orbital region. However, VAB in Astyanax is only correlated with the number of neuromasts on the left side. Astyanax also have a bent skull preferentially to the left and a QTL signal for the right-side number of neuromasts. We conducted field studies in five different cave populations for four years. Results support that all cave populations can express behavioral lateralization or preponderance of side to examine a vibrating object. The percentage of individuals favoring one side may change among pools and years. In one cave population (Pachón), for one year, this “handedness” was expressed by preferentially using the right side of their face. On the contrary, in most years and pools, Tinaja, Sabinos, Molino, and Toro cave populations explored preferentially using their left side. This suggests that if there is an adaptative effect, it selects for asymmetry on itself, and not necessarily for which side is the one to be specialized. Results also showed that the laterality varied depending on how responsive an individual fish was, perhaps due to its nutritional, motivational state, or mode of stimuli most relevant at the time for the fish.

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Research Article Tue, 13 Sep 2022 10:54:23 +0300
Divergent evolutionary pathways for aggression and territoriality in Astyanax cavefish https://subtbiol.pensoft.net/article/79318/ Subterranean Biology 43: 169-183

DOI: 10.3897/subtbiol.73.79318

Authors: Luis Espinasa, Emily Collins, C. Patricia Ornelas García, Sylvie Rétaux, Nicolas Rohner, Jennifer Rutkowski

Abstract: The surface morph of the Mexican tetra fish (Astyanax mexicanus) exhibits strong territoriality behavior and high levels of aggression. In contrast, the eyeless cave-adapted morph from Sierra de El Abra, México, rarely are aggressive and have totally lost the territorial behavior. These behaviors are part of what has been called the cavefish behavioral syndrome. Here, we report that several Astyanax cave populations of Sierra de Guatemala, unlike those reported for the Sierra de El Abra cave populations, display significant territoriality and aggression when confined into a reduced space. We discuss divergent evolutionary trajectories in terms of agonistic behavior for cavefish populations inhabiting different mountain ranges.

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Research Article Fri, 15 Jul 2022 03:53:31 +0300
Reproduction, development, asymmetry and late eye regression in the Brazilian cave catfish Ituglanis passensis (Siluriformes, Trichomycteridae): evidence contributing to the neutral mutation theory https://subtbiol.pensoft.net/article/60691/ Subterranean Biology 38: 91-112

DOI: 10.3897/subtbiol.31.60691

Authors: Sandro Secutti, Eleonora Trajano

Abstract: The troglobitic (exclusively subterranean source population) catfish Ituglanis passensis (Siluriformes, Trichomycteridae) is endemic to the Passa Três Cave, São Domingos karst area, Rio Tocantins basin, Central Brazil. This unique population presents variably reduced eyes and melanic pigmentation. We describe reproduction and early development in this species based on a spontaneous (non-induced) reproductive-event that occurred in the laboratory in January–February, 2009, while simultaneously comparing with data from the cave-habitat and a previous reproductive event. Egg laying was parceled. Egg-size and number were within variations observed in epigean congeners. Larvae behavior and growth is described. A single surviving specimen was monitored over two years. Eye-regression started late, one year after birth, and followed a pattern of stasis phases intercalated with slow growth and fluctuating asymmetric rates. Late eye regression, associated with asymmetry in eye development and intra-population variability of troglomorphic traits, as shown by several Brazilian subterranean fishes, provide support for the Neutral Mutation Theory.

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Research Article Mon, 19 Apr 2021 08:19:33 +0300
Hydraulic flow resistance of epigean and hypogean fish of the family Trichomycteridae (Ostariophysi, Siluriformes) https://subtbiol.pensoft.net/article/55064/ Subterranean Biology 35: 97-110

DOI: 10.3897/subtbiol.35.55064

Authors: Francisco Alexandre Costa Sampaio, Marina Silva Rufino, Paulo Santos Pompeu, Hersília de Andrade е Santos, Rodrigo Lopes Ferreira

Abstract: Critical swimming speeds of four trichomycterid fish species from epigean and hypogean environments were analyzed and compared: Trichomycterus itacarambiensis and Ituglanis passensis, both troglobitic from underground rivers; Trichomycterus brasiliensis, from epigean rivers; and Ituglanis sp., an undescribed troglophilic species from an underground stream. Swimming tests were conducted with a non-volitional apparatus in which fish swim against a progressive incremental water velocity until they longer resist the flow. Total length was significantly related to critical speed for only T. itacarambiensis. The critical speed obtained by each species, in decreasing order, with values in lengths per second (lengths/s), were: I. passensis (3.61), T. itacarambiensis (3.49), T. brasiliensis (3.11) and Ituglanis sp. (1.89). Swimming performance differed between the congeners T. itacarambiensis and T. brasiliensis, but did not differed between I. passensis and Ituglanis sp. The greater speed for the troglobitic species compared to that of the troglophilic and epigean species is probably related to seasonal flooding pulses that can be extremely severe in caves. Furthermore, during the tests, fish were observed using their mouth and/or barbels to fasten themselves to the substrate to avoid high flows.

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Research Article Fri, 23 Oct 2020 08:22:32 +0300
Troglomorphic features of Astroblepus pholeter, a cavefish from Ecuador, and possible introgressive hybridization https://subtbiol.pensoft.net/article/27098/ Subterranean Biology 27: 17-29

DOI: 10.3897/subtbiol.27.27098

Authors: Luis Espinasa, Jenna Robinson, Daphne Soares, Geoffrey Hoese, Theofilos Toulkeridis, Rickard Toomey III

Abstract: Cave organisms are often characterized by reduced pigmentation, eyesight, and enhanced mechanosensory functions. The stygobitic catfish Astroblepus pholeter is found within some subterranean drainages in Ecuador. The species was first described in 1962 with specimens that were all highly depigmented and troglomorphic. The next observations in the field occurred until 2011, 2015 and 2018. At such dates, specimens examined progressively displayed more surface-like appearance. Appendages in these individuals were progressively shorter and pigmentation levels are now as high as some surface Astroblepus. Based on sampled specimens, it would appear that since 1962, the population has been progressively composed of less troglomorphic individuals. One possibility is that the population has undergone introgressive hybridization in recent years as surface Astroblepus are known to enter the caves and cohabitate with the troglomorphic Astroblepus. Lastly, we report that Individuals are able to detect and respond to light. Histological analyses show that A. pholeter’s eyes have all of the major ocular structures (lens, optic nerve, and all retinal layers).

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Research Article Wed, 15 Aug 2018 10:37:19 +0300
Phylogeographical convergence between Astyanax cavefish and mysid shrimps in the Sierra de El Abra, Mexico https://subtbiol.pensoft.net/article/27097/ Subterranean Biology 26: 75-84

DOI: 10.3897/subtbiol.26.27097

Authors: Joseph Kopp, Shristhi Avasthi, Luis Espinasa

Abstract: The Sierra de El Abra is a long (120 km) and narrow (10 km) karstic area in northeastern Mexico. Some studies have suggested independent evolutionary histories for the multiple populations of blind cavefish Astyanax mexicanus that inhabit this mountain range, despite the hydrological connections that may exist across the Sierra. Barriers between caves could have prevented stygobitic populations to migrate across caves, creating evolutionary significant units localized in discrete biogeographical areas of the Sierra de El Abra. The goal of the present study was to evaluate if there is a correspondence in phylogeographical patterns between Astyanax cavefish and the stygobitic mysid shrimp Spelaeomysis quinterensis. Astyanax mtDNA and mysid histone H3 DNA sequences showed that in both species, cave populations in central El Abra, such as Tinaja cave, are broadly different from other cave populations. This phylogeographical convergence supports the notion that the central Sierra de El Abra is a biogeographical zone with effective barriers for either cave to cave or surface to cave gene flow, which have modulated the evolutionary history across species of its aquatic stygobitic community.

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Research Article Tue, 14 Aug 2018 16:46:25 +0300
A new cave locality for Astyanax cavefish in Sierra de El Abra, Mexico https://subtbiol.pensoft.net/article/26643/ Subterranean Biology 26: 39-53

DOI: 10.3897/subtbiol.26.26643

Authors: Luis Espinasa, Laurent Legendre, Julien Fumey, Maryline Blin, Sylvie Rétaux, Monika Espinasa

Abstract: The characiform fish Astyanax mexicanus comes in two forms, a surface-dwelling morph which lives in the rivers of North and Central America and a blind, depigmented cave-dwelling morph which inhabits caves in Mexico. In recent years, this species has arguably become among the most influential model system for the study of evolutionary development and genomics in cave biology. While recent articles have analysed in great detail Astyanax genetics, development, physiology, phylogeny and behaviour, there have been comparatively few recent studies concerning its ecology and in particular its biogeography. Mitchell et al. (1977) reported the species inhabiting 29 caves in the Sierra de El Abra region. Despite the elapsing of over 40 years and the latest surge of interest in the model, not a single new cave locality had been described for the species. We describe here a new and 30th cave locality, Chiquitita Cave, inhabited by troglomorphic A. mexicanus. Their morphology, eye histology, 16S rRNA DNA sequence, and smelling capabilities are analysed. This cave represents the southernmost extension for the cave morph’s habitat within the Sierra de El Abra. Its name, Chiquitita Cave (Tiny Cave), was chosen in reference to a potential hydrologic connection to “Chica Cave” (small cave), which is among the most studied populations of Astyanax.

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Research Article Wed, 4 Jul 2018 09:40:58 +0300
Contrasting feeding habits of post-larval and adult Astyanax cavefish https://subtbiol.pensoft.net/article/11046/ Subterranean Biology 21: 1-17

DOI: 10.3897/subtbiol.21.11046

Authors: Luis Espinasa, Natalie Bonaroti, Jae Wong, Karen Pottin, Eric Queinnec, Sylvie Rétaux

Abstract: The subterranean environment is often described as “extreme” and food poor. Laboratory experiments have shown that blind Mexican tetra Astyanax mexicanus (De Filippi, 1853) cavefish are better at finding food in the dark than surface fish. Several morphological and behavioural attributes that could foster this obvious adaptive response to cave environments have been described. Nonetheless, it is currently unknown what young cavefish actually eat in their natural cave environment. Our results from the Pachón cave in México during the dry and rainy season show that fry are efficient predators in their natural cave environment. Their primary food item is aquatic crustaceans. The guts of post-larval, pre-juvenile stage individuals (n=9) contained an average of 17.9 water fleas (Cladocera), copepods, ostracods, and isopods. Thus, the fry in this cave are well-fed. The Pachón cave environment does not appear to be “food poor” for juvenile cavefish. Food regimes change between post-larval and adult stages to become more dependent on partially decomposed material, guano, or detritus from the mud. We discuss the data with regards to our current developmental and genetic understanding of cavefish morphological and behavioural evolution, particularly regarding its enhanced Vibration Attraction Behaviour (VAB).

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Research Article Fri, 6 Jan 2017 15:25:49 +0200
First definitive record of a stygobiotic fish (Percopsiformes, Amblyopsidae, Typhlichthys) from the Appalachians karst region in the eastern United States https://subtbiol.pensoft.net/article/9693/ Subterranean Biology 20: 39-50

DOI: 10.3897/subtbiol.20.9693

Authors: Matthew L. Niemiller, Kirk S. Zigler, Pamela B. Hart, Bernard R. Kuhajda, Jonathan W. Armbruster, Breanne N. Ayala, Annette S. Engel

Abstract: In the central and eastern United States, cavefishes have been known historically only from the Interior Low Plateau and Ozarks karst regions. Previously, cavefishes were unknown from the Appalachians karst region, which extends from southeastern New York southwestward into eastern Tennessee, northwestern Georgia, and northeastern Alabama. Here we report the discovery of a new population of the amblyopsid cavefish Typhlichthys subterraneus Girard, 1859 from a cave in Catoosa County, Georgia, that significantly extends the known distribution of the species. The cave is located in the Appalachian Valley and Ridge physiographic province and Appalachians karst region, and represents the first definitive report of a stygobiotic fish from the Appalachians karst region. Genetic analyses of one mitochondrial and one nuclear locus from the cavefish indicate this population is closely allied with populations that occur along the western margins of Lookout and Fox mountains in Dade County, Georgia, and populations to the northwest in southern Marion County, Tennessee. It is likely that these populations are also related to those from Wills Valley, DeKalb County, Alabama. The distribution of this new population of T. subterraneus and its close allies pre-dates the emergence of a Tennessee-Coosa River drainage divide in the Pliocene. The potential exists to discover additional populations in caves within the Appalachians karst region in Catoosa County and northward into Hamilton County, Tennessee.

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Research Article Tue, 8 Nov 2016 09:54:09 +0200
Spontaneous behavior of basal Copionodontinae cave catfishes from Brazil (Teleostei, Siluriformes, Trichomycteridae) https://subtbiol.pensoft.net/article/5180/ Subterranean Biology 16: 61-77

DOI: 10.3897/subtbiol.16.5180

Authors: Bianca Rantin, Maria Bichuette

Abstract: Cave animals are particularly interesting due to their behavioral specializations, resultant from evolution in isolation. We present data from a spontaneous behavior study (spatial distribution and preference for microhabitats) of two troglobitic catfish from Brazil: Glaphyropoma spinosum and a new species of Copionodon. We compared the data with those obtained of a sympatric epigean species, Copionodon pecten. These Trichomycteridae species belong to a basal and apparently monophyletic subfamily – Copionodontinae, endemic to Chapada Diamantina, central Bahia state, eastern Brazil. We observed the fishes in natural and laboratory conditions through ad libitum and focal animal methods. Each spatial behavioral category (hidden, bottom, midwater, surface and wall swimming and stationary in the bottom) was timed individually, with a sample of 12 specimens per species. Unlike most troglobitic fishes, cave copionodontines tested herein did not extend exploratory behavior to midwater, with benthonic and thigmotactic-related exploratory behavior. This behavior is possibly related to its feeding behavior specializations, strong territorialism and photophobic behavior. The epigean Copionodon species is also benthonic. The spatial behavior of the cave Copionodontinae could be interpreted as a retained and plesiomorphic character-state in relation to other trichomycterid catfishes.

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Research Article Fri, 7 Aug 2015 09:47:17 +0300