Showing papers in "Copeia in 2003"
1,103 citations
219 citations
TL;DR: Spectrophotometry of the lens, cornea, and humors for 195 species from 49 families found that the spectral composition of the light transmitted to the retina was most often limited by the lens (73% of species examined), and these species could possess true UV-color vision and hue discrimination.
Abstract: The visual biology of Hawaiian reef fishes was explored by examining their eyes for spectral sensitivity of their visual pigments and for transmission of light through the ocular media to the retina. The spectral absorption curves for the visual pigments of 38 species of Hawaiian fish were recorded using microspectrophotometry. The peak absorption wavelength (λmax) of the rods varied from 477–502 nm and the λmax of individual species conformed closely to values for the same species previously reported using a whole retina extraction procedure. The visual pigments of single cone photoreceptors were categorized, dependent on their λmax-values, as ultraviolet (347–376 nm), violet (398–431 nm) or blue (439–498 nm) sensitive cones. Eight species possessed ultraviolet-sensitive cones and 14 species violet-sensitive cones. Thus, 47% of the species examined displayed photosensitivity to the short-wavelength region of the spectrum. Both identical and nonidentical paired and double cones were found with bl...
193 citations
TL;DR: Much of the book is taken up with recounting candiru anecdotes reported by scientists, explorers, and adventurers, and considerable space is devoted to the field and laboratory experiences of Spotte and his colleagues Paulo Petry and Jansen A. S. Zuanon.
Abstract: CANDIRU: LIFE AND LEGEND OF THE BLOODSUCKING CATFISHES. Stephen Spotte. 2002. Creative Arts Book Company, 833 Bancroft Way, Berkeley, California 94710. ISBN 088739-469-8. xii 1 322 p. $24.50 (paperback).—It might be difficult to devise a title more attractive to ichthyologists and others steeped in fish lore than the one created for this book; titles of some of the chapters (Urinary Misconduct, Embracing Urine, Hora do Amor) may entice those with other interests. In some detail Spotte presents descriptive material for the 15 species of catfishes (mostly in the genera Vandellia and Plectrochilus) that he considers as candirus (family Trichomycteridae: subfamily Vandelliinae). His definition (p. 4, repeated on p. 50) of candiru(s) is ‘‘those trichomycterid catfishes known to suck blood from the gills of other fishes and thought to live on blood exclusively.’’ His concept of candiru, as he acknowledges in an endnote (p. 233, Endnote 9), differs from that of some authors: ‘‘I’ve taken the additional liberty of assuming those species I call ‘true’ candirus are obligate bloodsuckers, although the existence of exclusively sanguinivorous fishes requires confirmation.’’ The proclivities, or alleged proclivities, of candirus to enter orifices of the human body have aroused the prurient interests of adolescents of all ages. The vagina and urethra seem to be the portals of choice, with the anus also reported to have received the attention of these fishes. There are even stories of candirus entering ears and noses. In the penultimate chapter entitled The Smoking Gun, Spotte provided a detailed account of a candiru encounter that occurred in October 1997 during a young man’s untoward riverine micturating experience. According to that report, the invading ‘‘fish had darted out of the water, up the urine stream, and into his urethra’’ (p. 213, emphasis in the original). Much of the book is taken up with recounting candiru anecdotes reported by scientists, explorers, and adventurers, and considerable space is devoted to the field and laboratory experiences of Spotte and his colleagues Paulo Petry and Jansen A. S. Zuanon. The author and associates expended considerable effort collecting candirus and later conducted experiments designed to illuminate their behavior. In the Introduction (p. xi), the author stated: ‘‘My narrative is neither wholly factual nor entirely fictitious. . . . The candiru hovers before us like a wraith, its biology no less elusive than its legend.’’ In much of the text, Spotte interleaves myth and hearsay with fact, explanation, and disbelief and in the last chapter, Candiru World, best left unread, wanders off into a realm of fantasia. For ichthyologists, the most important contributions in the book are the presentation (in chapters 3 and 4) of descriptions from the literature of candiru taxa (many in translation with their sources in the original languages provided in the endnotes) and the compilation of references, constituting a Literature Cited of 22 pages. The 57 black-and-white illustrations are generally appropriate and mostly good, and the eight plates (four in color) are good to excellent. Candiru will appeal mainly to those interested in the freshwater fishes of South America or captivated by the mystique of the Amazon basin. This is Contribution Number 204 of the Grice Marine Biological Laboratory.
165 citations
TL;DR: This is the first complete report of occurrence and pathology of chytridiomycosis in Salamanders in field-collected North American salamanders, and it is demonstrated that chyTridiomyCosis does not always lead to mortality.
Abstract: A chytrid fungus, Batrachochytrium dendrobatidis, was found in salamanders, Ambystoma tigrinum stebbinsi, collected in southern Arizona, USA. The chytrid was isolated and cultured, and Koch’s postulates were satisfied by infection of metamorphosed salamanders with pure culture and subsequent reisolation from these salamanders. We used the salamander strain and a strain isolated from lowland leopard frogs in Arizona, Rana yavapaiensis, to infect metamorphosed A. tigrinum, R. yavapaiensis, and R. boylii. All three species became infected, but none of the infected salamanders died within 60 days, and mortality of infected frogs did not differ significantly from controls, although sample size was small. Chytrid infection could not be detected by light histology in most of the infected frogs and one of the infected salamanders 60 days after infection. To date, there are three records of chytridiomycosis in salamanders on websites; ours is the first complete report of occurrence and pathology of chytridiomycosis in field-collected North American salamanders. Our results also demonstrate that chytridiomycosis does not always lead to mortality. Individuals within a species vary in susceptibility to infection, animals appear to recover from the infection, and syntopic salamanders and frogs may act as reciprocal pathogen reservoirs for chytrid infections.
156 citations
151 citations
TL;DR: Much of the book is taken up with recounting candiru anecdotes reported by scientists, explorers, and adventurers, and considerable space is devoted to the field and laboratory experiences of Spotte and his colleagues Paulo Petry and Jansen A. S. Zuanon.
Abstract: CANDIRU: LIFE AND LEGEND OF THE BLOODSUCKING CATFISHES. Stephen Spotte. 2002. Creative Arts Book Company, 833 Bancroft Way, Berkeley, California 94710. ISBN 088739-469-8. xii 1 322 p. $24.50 (paperback).—It might be difficult to devise a title more attractive to ichthyologists and others steeped in fish lore than the one created for this book; titles of some of the chapters (Urinary Misconduct, Embracing Urine, Hora do Amor) may entice those with other interests. In some detail Spotte presents descriptive material for the 15 species of catfishes (mostly in the genera Vandellia and Plectrochilus) that he considers as candirus (family Trichomycteridae: subfamily Vandelliinae). His definition (p. 4, repeated on p. 50) of candiru(s) is ‘‘those trichomycterid catfishes known to suck blood from the gills of other fishes and thought to live on blood exclusively.’’ His concept of candiru, as he acknowledges in an endnote (p. 233, Endnote 9), differs from that of some authors: ‘‘I’ve taken the additional liberty of assuming those species I call ‘true’ candirus are obligate bloodsuckers, although the existence of exclusively sanguinivorous fishes requires confirmation.’’ The proclivities, or alleged proclivities, of candirus to enter orifices of the human body have aroused the prurient interests of adolescents of all ages. The vagina and urethra seem to be the portals of choice, with the anus also reported to have received the attention of these fishes. There are even stories of candirus entering ears and noses. In the penultimate chapter entitled The Smoking Gun, Spotte provided a detailed account of a candiru encounter that occurred in October 1997 during a young man’s untoward riverine micturating experience. According to that report, the invading ‘‘fish had darted out of the water, up the urine stream, and into his urethra’’ (p. 213, emphasis in the original). Much of the book is taken up with recounting candiru anecdotes reported by scientists, explorers, and adventurers, and considerable space is devoted to the field and laboratory experiences of Spotte and his colleagues Paulo Petry and Jansen A. S. Zuanon. The author and associates expended considerable effort collecting candirus and later conducted experiments designed to illuminate their behavior. In the Introduction (p. xi), the author stated: ‘‘My narrative is neither wholly factual nor entirely fictitious. . . . The candiru hovers before us like a wraith, its biology no less elusive than its legend.’’ In much of the text, Spotte interleaves myth and hearsay with fact, explanation, and disbelief and in the last chapter, Candiru World, best left unread, wanders off into a realm of fantasia. For ichthyologists, the most important contributions in the book are the presentation (in chapters 3 and 4) of descriptions from the literature of candiru taxa (many in translation with their sources in the original languages provided in the endnotes) and the compilation of references, constituting a Literature Cited of 22 pages. The 57 black-and-white illustrations are generally appropriate and mostly good, and the eight plates (four in color) are good to excellent. Candiru will appeal mainly to those interested in the freshwater fishes of South America or captivated by the mystique of the Amazon basin. This is Contribution Number 204 of the Grice Marine Biological Laboratory.
146 citations
TL;DR: Results suggest that the occurrence of potent neurotoxic component(s) in a venom minimizes predigestive components (metalloproteases); concurrence of these functional components in the venom of an individual may be selected against, and highly toxic venom in both juvenile and adult C. o.
Abstract: Ontogenetic shifts in diet are common for snakes, and such shifts in diet for venomous snakes may be associated with changes in venom composition. The present study investigated whether an ontogenetic shift in diet and venom composition, as observed for Crotalus oreganus helleri and Crotalus oreganus oreganus, occurs in Crotalus oreganus concolor. Like C. o. helleri and C. o. oreganus, and at similar body sizes, C. o. concolor show an ontogenetic shift in diet. Juvenile snakes primarily feed on small lizards, whereas adults typically consume small rodents. However, C. o. concolor do not show the same pattern of venom ontogeny as do C. o. helleri and C. o. oreganus. Because of the presence of a phospholipase A2-based β-neurotoxin (concolor toxin) and several myotoxins, C. o. concolor venom is particularly toxic, but mouse LD50 assays demonstrated no significant difference in toxicity between adult (0.38 μg/g) and juvenile (0.45 μg/g) venoms. Metalloprotease activity (correlated with extensive tiss...
135 citations
TL;DR: The model predicts that the task of distinguishing green algae from coral is optimized with a relatively long wavelength visual pigment pair, and Herbivorous grazers whose visual pigments are known possess the longest sensitivities so far found.
Abstract: In the previous two papers in this three-part series, we have examined visual pigments, ocular media transmission, and colors of the coral reef fish of Hawaii. This paper first details aspects of the light field and background colors at the microhabitat level on Hawaiian reefs and does so from the perspective and scale of fish living on the reef. Second, information from all three papers is combined in an attempt to examine trends in the visual ecology of reef inhabitants. Our goal is to begin to see fish the way they appear to other fish. Observations resulting from the combination of results in all three papers include the following. Yellow and blue colors on their own are strikingly well matched to backgrounds on the reef such as coral and bodies of horizontally viewed water. These colors, therefore, depending on context, may be important in camouflage as well as conspicuousness. The spectral characteristics of fish colors are correlated to the known spectral sensitivities in reef fish single ...
132 citations
TL;DR: The proportional change in body size of island snakes was bimodal, consistent with a diet alteration hypothesis that suggests that snake body size is principally influenced by prey size and that island snakes encounter prey that are larger or smaller in size compared with those on the mainland.
Abstract: The current literature reports divergent conclusions on the patterns of body size change in island snakes. I reviewed body size data in the published literature and tested the effects of island biogeographic variables on such changes. I found that none of the physiographic variables (island area, island age, distance to mainland, and latitude) was important in determining changes in size of island snakes. Additionally, a current hypothesis of phylogenetic history had no effect on changes in body size. Rather, the proportional change in body size of island snakes was bimodal, consistent with a diet alteration hypothesis that suggests that snake body size is principally influenced by prey size and that island snakes encounter prey that are larger or smaller in size compared with those on the mainland. Also, snakes that became small on islands did so to a relatively greater degree than those that became large. Ontogenetic changes in foraging strategies appeared to explain this pattern. The distribut...
130 citations
TL;DR: Much of the book is taken up with recounting candiru anecdotes reported by scientists, explorers, and adventurers, and considerable space is devoted to the field and laboratory experiences of Spotte and his colleagues Paulo Petry and Jansen A. S. Zuanon.
Abstract: CANDIRU: LIFE AND LEGEND OF THE BLOODSUCKING CATFISHES. Stephen Spotte. 2002. Creative Arts Book Company, 833 Bancroft Way, Berkeley, California 94710. ISBN 088739-469-8. xii 1 322 p. $24.50 (paperback).—It might be difficult to devise a title more attractive to ichthyologists and others steeped in fish lore than the one created for this book; titles of some of the chapters (Urinary Misconduct, Embracing Urine, Hora do Amor) may entice those with other interests. In some detail Spotte presents descriptive material for the 15 species of catfishes (mostly in the genera Vandellia and Plectrochilus) that he considers as candirus (family Trichomycteridae: subfamily Vandelliinae). His definition (p. 4, repeated on p. 50) of candiru(s) is ‘‘those trichomycterid catfishes known to suck blood from the gills of other fishes and thought to live on blood exclusively.’’ His concept of candiru, as he acknowledges in an endnote (p. 233, Endnote 9), differs from that of some authors: ‘‘I’ve taken the additional liberty of assuming those species I call ‘true’ candirus are obligate bloodsuckers, although the existence of exclusively sanguinivorous fishes requires confirmation.’’ The proclivities, or alleged proclivities, of candirus to enter orifices of the human body have aroused the prurient interests of adolescents of all ages. The vagina and urethra seem to be the portals of choice, with the anus also reported to have received the attention of these fishes. There are even stories of candirus entering ears and noses. In the penultimate chapter entitled The Smoking Gun, Spotte provided a detailed account of a candiru encounter that occurred in October 1997 during a young man’s untoward riverine micturating experience. According to that report, the invading ‘‘fish had darted out of the water, up the urine stream, and into his urethra’’ (p. 213, emphasis in the original). Much of the book is taken up with recounting candiru anecdotes reported by scientists, explorers, and adventurers, and considerable space is devoted to the field and laboratory experiences of Spotte and his colleagues Paulo Petry and Jansen A. S. Zuanon. The author and associates expended considerable effort collecting candirus and later conducted experiments designed to illuminate their behavior. In the Introduction (p. xi), the author stated: ‘‘My narrative is neither wholly factual nor entirely fictitious. . . . The candiru hovers before us like a wraith, its biology no less elusive than its legend.’’ In much of the text, Spotte interleaves myth and hearsay with fact, explanation, and disbelief and in the last chapter, Candiru World, best left unread, wanders off into a realm of fantasia. For ichthyologists, the most important contributions in the book are the presentation (in chapters 3 and 4) of descriptions from the literature of candiru taxa (many in translation with their sources in the original languages provided in the endnotes) and the compilation of references, constituting a Literature Cited of 22 pages. The 57 black-and-white illustrations are generally appropriate and mostly good, and the eight plates (four in color) are good to excellent. Candiru will appeal mainly to those interested in the freshwater fishes of South America or captivated by the mystique of the Amazon basin. This is Contribution Number 204 of the Grice Marine Biological Laboratory.
TL;DR: Social interactions including contests between males and courtship of females appear to be stressful in free-living male S. undulatus.
Abstract: Understanding the spacing patterns of individuals in a population of animals is important for establishing the specific functions of territorial behavior. Here, we couple a comprehensive analysis of home range with demographic information and focal behavioral observations of Sceloporus undulatus (eastern fence lizard) to investigate (1) spacing patterns, (2) the determinants of home range, and (3) the functional significance of territorial behavior and traits related to territorial behavior (body size, color). Male home-range area is an order of magnitude larger in the New Jersey population of S. undulatus described here than in other populations, whereas female home ranges are comparable in area to other populations of this species. Home-range area is positively correlated with body size in adult males, although this relationship is not found within age classes, and males share about 50% of their home range with other males. After removal of the effect of body size, residual home-range area is s...
TL;DR: In this paper, the authors compared headwater assemblages of the unimpounded East Fork and the impounded West Fork of the San Jacinto River in Texas using multiple regression and canonical ordination, and partitioned variation in species distributions into that explained by instream structural, hydrologic, and physicochemical factors, drainage features, and season.
Abstract: Hydrologic variability and connectivity influence stream-fish assemblage structure, but other correlated habitat variables often confound attempts to document such relationships. By their nature, dams decrease stream connectivity, but upstream influences on tributary fish assemblages are infrequently documented and poorly understood. We sampled stream fishes seasonally for one year to compare headwater assemblages of the unimpounded East Fork (nine sites) and the impounded West Fork (12 sites) of the San Jacinto River in Texas. Using multiple regression and canonical ordination, we partitioned variation in species' distributions into that explained by instream structural, hydrologic, and physicochemical factors, drainage features, and season. In addition to effects of temporal variation of connectivity (as related to base flow and season) and other environmental factors, spatial patterns of species distribution between tributaries in the East and West Fork indicated upstream effects of impoundment caused by two probable mechanisms. Lentic habitats of impounded lower reaches in the West Fork apparently reduced movement by fluvial specialists among streams and, thus, reduced their opportunity to recolonize dry reaches compared to populations in East Fork streams. Moreover, West Fork assemblages had more macrohabitat-generalist species, which were abundant in the littoral zone of the impoundment and able to recolonize or tolerate environmental conditions in intermittent reaches. We caution that upstream effects of impoundment could be mistakenly attributed to other factors if they are not explicitly considered in species-environment studies.
TL;DR: Similar to laboratory responses, seasonally acclimatized Atlantic stingrays tuned their physiology to the low cycle temperatures that were most threatening to continued survival.
Abstract: Atlantic stingrays, Dasyatis sabina, inhabit shallow bays subject to rapid temperature changes, yet little is known about their thermal tolerance strategies. We quantified critical thermal maxima (CTMaxima) and minima (CTMinima) of Atlantic stingrays from St. Joseph's Bay, Florida. Spiracle contraction cessation for more than one minute was the experimental endpoint. Laboratory-acclimated fish held at 10.8, 20.5, or 35.1 C exhibited CTMaxima of 35.7, 39.3, or 43.2 C, and CTMinima of 0.8, 4.8, or 10.8 C, respectively. Regression analysis revealed that CTMaxima increased by 0.31 C and CTMinima decreased by 0.41 C for every 1.0 C increase in acclimation temperature. Atlantic stingrays exposed to diel thermoperiods of 34.0–37.3 C and 7.0–11.0 C had CTMaxima of 43.1 and 33.4 C and CTMinima of 9.6 and 0.3 C, respectively, suggesting that fish acclimated to low cycle temperatures. A thermal tolerance polygon produced from laboratory data had an area of 978 C2, the third largest ever measured in a fish. ...
TL;DR: The colors of 51 species of Hawaiian reef fish have been measured using a spectrometer and therefore can be described in objective terms that are not influenced by the human visual experience, and trends in fish colors can be seen that are indicative of both visually driven selective pressures and chemical or physical constraints on the design of colors.
Abstract: The colors of 51 species of Hawaiian reef fish have been measured using a spectrometer and therefore can be described in objective terms that are not influenced by the human visual experience. In common with other known reef fish populations, the colors of Hawaiian reef fish occupy spectral positions from 300-800nm; yellow or orange with blue, yellow with black, and black with white are the most frequently combined colors; and there is no link between possession of ultraviolet (UV) reflectance and UV visual sensitivity or the potential for UV visual sensitivity. In contrast to other reef systems, blue, yellow, and orange appear more frequently in Hawaiian reef fish. Based on spectral quality of reflections from fish skin, trends in fish colors can be seen that are indicative of both visually driven selective pressures and chemical or physical constraints on the design of colors. UV-reflecting colors can function as semiprivate communication signals. White or yellow with black form highly contrasting patterns that transmit well through clear water. Labroid fishes display uniquely complex colors but lack the ability to see the UV component that is common in their pigments. Step-shaped spectral curves are usually long-wavelength colors such as yellow or red, and colors with a peak-shaped spectral curves are green, blue, violet, and UV.
TL;DR: Relationships among the 18 extant species of parasitic lamprey (Petromyzontiformes) were determined using a cladistic analysis of 32 mainly morphological characters, revealing a trichotomy between a monophyletic northern hemisphere clade and the southern hemisphere genera Geotria and Mordacia.
Abstract: Relationships among the 18 extant species of parasitic lamprey (Petromyzontiformes) were determined using a cladistic analysis of 32 mainly morphological characters. Because previous analyses support all known fossils as phylogenetically older or the same age as living lampreys, a composite agnathan fossil was used as an outgroup. A consensus of three equally parsimonious trees revealed a trichotomy between a monophyletic northern hemisphere clade and the southern hemisphere genera Geotria and Mordacia. The monophyletic status of the northern hemisphere lampreys and their classification in a single family Petromyzontidae was corroborated. It is suggested that the two southern hemisphere lamprey genera be retained as distinct families. Among northern hemisphere species, Ichthyomyzon and Petromyzon form a monophyletic group sister to the remaining genera. Caspiomyzon is sister to Tetrapleurodon + Entosphenus + Lethenteron + Eudontomyzon + Lampetra, with Tetrapleurodon in turn being sister to a grou...
TL;DR: The monophyly of both natalis and catus clades was rejected by the nucleotide dataset and an alternative phylogenetic hypothesis is provided.
Abstract: Catfishes of the genus Ameiurus are a well-known component of the North American ichthyofauna. J. G. Lundberg estimated phylogenetic relationships among species of Ameiurus according to morphological variation. Two clades containing the extant species were recovered: the natalis clade (Ameiurus natalis, Ameiurus melas, and Ameiurus nebulosus) and the catus clade (Ameiurus serracanthus, Ameiurus catus, Ameiurus platycephalus, and Ameiurus brunneus). Original nucleotide sequence data were collected from mitochondrial (cytochrome b) and nuclear (recombination activation gene 2) genes and used to test the predictions of the hypothesis based on morphological data. The monophyly of both natalis and catus clades was rejected by the nucleotide dataset and an alternative phylogenetic hypothesis is provided.
TL;DR: It is concluded that the use of general formulas to reconstruct the volumes of arthropods are not appropriate for most studies of diet overlap and that extreme care should be exercised in attempts to perform meta-analyses on studies that purportedly measured prey volumes.
Abstract: Studies of diet overlap of insectivores, especially lizards, have been important for the development of much ecological theory. However, measures of overlap, usually based on dietary volumes, vary widely among studies. Most researchers estimated the volumes of prey in stomach contents subjectively or attempted to reconstruct the volume of individual prey items from linear measurements of length (L), width (W) and/or height (H), or from mass. We studied the relationship between indices of volume based on indirect measures and direct measures of volume by fluid displacement for a collection of arthropods that simulated the diet of a generalist lizard. For each individual arthropod, we calculated the proportional error [(measured volume—estimated volume)/measured volume)] for each estimation method. For individual large insects, there were significant differences between orders in the proportional error for all methods. The methods based on linear measurements had only weak relationships (r2 ≤ 0.4 i...
TL;DR: Females were found farther from the breeding site than were males, and mean home ranges, as calculated by the adaptive kernel method, were four times larger for females than for males.
Abstract: I sampled movements and amount of area used by boreal toads (Bufo boreas) between June and October for 3 yr. Females were found farther from the breeding site than were males, and mean home ranges, as calculated by the adaptive kernel method, were four times larger for females than for males. Temperature and snow accumulation were comparable over the study, but data collection was hampered by mortality of animals caused by an outbreak of amphibian chytridiomycosis in yr 2. These data provide insight into use of habitat by boreal toads in undisturbed areas but may not be typical of a completely healthy population.
TL;DR: Investigating the cues that guide species-isolating female choice in a group of sympatric Lake Malawi mbuna found that females courted only with conspecifics even if color was not a cue, likely based primarily on visual information.
Abstract: The mechanisms that underlie the diversity of cichlids in the East African Great Lakes are poorly understood. Sexual selection through female choice based on male body coloration has often been suggested as a driving force behind the speciation of these fishes. The objectives of this study were to investigate, through mate choice trials, the cues that guide species-isolating female choice. In a group of sympatric Lake Malawi mbuna (rock-dwelling fish), we investigated both visual and chemical cues that might guide female choice by giving gravid females a choice between a heterospecific and a conspecific male. Visual cues, in contrast to olfactory cues, were sufficient to stimulate courtship and thus guide female choice of males. Furthermore, in contrast to other studies on related species, we found that females courted only with conspecifics even if color was not a cue. Species-isolating female choice is likely based primarily on visual information.
TL;DR: It is shown that Danio, as recognized until now, is paraphyletic, and the well-known genus Brachydanio becomes a junior synonym of Danio (sensu stricto), and the phylogenetic relationships of small Danio-like species Sundadanio axelrodi, Danionella translucida, Danio erythromicron, and Microrasbora rubescens remain unresolved.
Abstract: A phylogenetic analysis of Danio (sensu lato), based on 38 morphological characters, shows that Danio, as recognized until now, is paraphyletic. Danio is restricted to species previously recognized as the “Danio dangila species group,” including D. dangila, Danio rerio, Danio nigrofasciatus, and Danio albolineatus. Those species share an “A stripe” on the anal-fin rays, an anterior lateral extension ventrally on the dentary, two or more pigment stripes on the caudal-fin rays and greatly enlarged lamellar nasal. Esomus is the sister group of Danio. Remaining Danio (sensu lato) species are referred to Devario, characterized by a short and wide premaxillary ascending process with a minute apophysis contacting the kinethmoid, a short maxillary barbel, a “P stripe” extending onto the median caudal-fin rays, and infraorbital 5 not or only slightly reduced. Devario includes the species Devario malabaricus, Devario kakhienensis, Devario devario, Devario chrysotaeniatus, Devario maetaengensis, Devario int...
TL;DR: According to the hypothesis that environmental conditions exert an important influence upon life-history parameters, populations under seasonal climates concentrate their reproductive effort during the short reproductive season, producing larger clutches, whereas those under more stable or unpredictable climates reproduce continuously, yielding smaller clutches.
Abstract: We investigated geographical variation in ecological parameters among populations of Cnemidophorus cryptus, Cnemidophorus gramivagus, Cnemidophorus lemniscatus, Cnemidophorus ocellifer, and Cnemidophorus parecis, from three Brazilian biomes (Cerrado, Caatinga, and Amazonian Savannas). Lizards used mainly the open ground, with a high similarity in microhabitat use among populations. Differences in microhabitat use probably resulted from the availability of microhabitats and not from microhabitat preferences. Body temperatures were high and little influenced by environmental temperatures, there being no differences among populations. There were significant differences in diet among populations, with C. ocellifer from Caatinga and Cerrado consuming large quantities of termites, whereas Amazonian Savanna species used primarily ants and insect larvae. The data on reproductive seasonality indicated cyclical reproduction in seasonal biomes and continuous reproduction in unpredictable climate regions. We...
TL;DR: Although the presumed female preference for swords predicts the introgression of swords from X. malinche-like populations into hybrid populations, the opposite pattern was observed, indicating that sexual selection does not act against recombinant phenotypes.
Abstract: The evolution of sexual signaling systems is influenced by natural and sexual selection acting on complex interactions among traits. Natural hybrid zones are excellent systems for assessing fitness effects on sexual phenotypes. Most documented hybrid zones, however, show little variation in sexual signals. A hybrid zone between the swordtails Xiphophorus birchmanni and Xiphophorus malinche is characterized by numerous recombinants for male sexual traits. Analyses of geographic variation in morphological and isozyme traits in the Rio Calnali, Hidalgo, Mexico, reveal an upstream-to-downstream gradient from X. malinche- to X. birchmanni-type traits. A second hybrid zone, likely isolated from the R. Calnali, occurs in the nearby Arroyo Pochutla. Although the presumed female preference for swords predicts the introgression of swords from X. malinche-like populations into hybrid populations, the opposite pattern was observed. Swords are reduced in populations otherwise characterized by X. malinche trai...
TL;DR: The simulated attack by a persistent predator on Acanthodactylus erythrurus lizards was simulated in the field and the characteristics of successive escape responses, microhabitats used for fleeing, and the refuges used were examined to suggest that lizards interpret persistent predatory attacks as an increase in predation risk and thatLizards adjusted the magnitude of their escape and antipredatory responses topredation risk level.
Abstract: We hypothesized that, through persistent predatory attacks, lizards should increase progressively the magnitude of their escape response. We simulated in the field a continuous attack by a persistent predator on Acanthodactylus erythrurus lizards and examined the characteristics of successive escape responses, microhabitats used for fleeing, and the refuges used. Lizards responded to the persistent attacks by increasing the distances they fled and the degree of cover in microhabitats into which they escaped. Lizards also changed their escape strategy from the first to the successive attacks. Initially, most individuals did not hide but stopped after running and remained vigilant, whereas almost all individuals hid subsequently. In addition, after successive predatory attacks, lizards used more structurally complex refuges (i.e., larger and with more obstructive cover). These refuges were probably safer although they may lower the lizard's capacity to observe the predator's subsequent behavior. Th...
TL;DR: The results suggest that melanin density plays a role in the presence of blue abdominal coloration in these phrynosomatid lizards.
Abstract: Phrynosomatid lizards show considerable variation among species in the occurrence of a secondary sexual trait, blue abdominal coloration. The production of blue skin may be controlled by at least two cellular components, melanin in melanophores, and guanine in iridophores. To examine the hypothesis that a mechanism producing variation in abdominal coloration is variation in the presence of melanin in the melanophores within the dermal layer of skin, we used light microscopy to compare melanin density of five species of phrynosomatid lizards with ancestral and derived abdominal coloration. Our results show that the skin of adults with blue abdominal coloration has more dermal melanin than white skin regardless of species or sex. We experimentally tested this relationship by examining the dermal melanin in skin from female Sceloporus undulatus consobrinus with exogenously elevated levels of testosterone or 5α-dihydrotestosterone. These females displayed malelike abdominal coloration and malelike me...