Chytridiomycosis is an emerging infectious disease of amphibians caused by the fungal pathogen Batrachochytrium dendrobatidis, and its role in causing population declines and species extinctions worldwide has created an urgent need for methods to detect it. Several reports indicate that in anurans chytridiomycosis can cause the depigmentation of tadpole tnouthparts, but the accuracy of using depigmentation to determine disease status remains uncertain. Our objective was to determine for the Mountain Yellow-legged Frog (Rana muscosa) whether visual inspections of the extent of tadpole mouthpart depigmentation could be used to accurately categorize individual tadpoles or R. muscosa populations as B. dendrobatidis-positive or negative. This was accomplished by assessing the degree of mouthpart depigmentation in tadpoles of known disease status (based on PCR assays). The depigmentation of R. muscosa tadpole mouthparts was associated with the presence of B. dendrobatidis, and this association was particularly strong for upper jaw sheaths. Using a rule that classifies tadpoles with upper jaw sheaths that are 100% pigmented as uninfected and those with jaw sheaths that are <100% pigmented as infected resulted in the infection status of 86% of the tadpoles being correctly classified. By applying this rule to jaw sheath pigmentation scores averaged across all tadpoles inspected per site, we were able to correctly categorize the infection status of 92% of the study populations. Similar research on additional anurans is critically needed to determine how broadly applicable our results for R. muscosa are to other species.
The relationship between different degrees of intraspecific crowding of reedfrog tadpoles and their physiological responses to a deterioration of the natal pond water quality was examined under laboratory conditions. Tadpoles that were reared at a lower density metamorphosed significantly earlier than those raised at a higher density. As density increases, the average body length at metamorphosis decreases. However, at low tadpole density, a significantly higher diversity of body size classes among freshly metamorphosed froglets was observed than under more crowded conditions. Mortality increased during metamorphic climax and was inversely correlated with the tadpole density. In ephemeral ponds, an accumulation of nitrogenous wastes from metabolic processes and/or a concentration by evaporation in prolonged rainless periods can pose a considerable chemical stress to reedfrog tadpoles. Hyperolius viridiflavus ommatostictus responded to an increasing ammonia concentration with an activity increase of the ornithine cycle (intensified urea synthesis). hi contrast, Hyperolius marmoratus taeniatus exhibited a strong tolerance against high ammonia levels. A deterioration of the natal pond water quality caused H. v. ommatostictus and H. v. nitidulus tadpoles to adjust to harsher climatic conditions at the time of metamorphosis. This physiological preadjustment enabled the froglets to start feeding and growing immediately after metamorphosis even at low air humidity and rare precipitation events. In contrast, froglets that were raised in daily refreshed water exhibited high mortality rates if subjected to identical conditions. As one possible indicator of the actual climatic conditions prevailing in the surrounding terrestrial habitat, fluctuations in the water ammonia level are discussed.
This paper analyzes data from the published literature with the addition of some new information to explore the relationship between varanid body size and repro- ductive biology. Incubation time for varanid eggs is positively correlated with egg mass, neonate snout-vent length (SVL), and maximum adult snout-vent length (SVLmax). Incubation period of heavier eggs is proportionally less than for smaller eggs at 30 C. SVLmax is positively correlated with egg mass, clutch size, clutch mass, neonate body mass, and neonate SVL. Neonates of larger species have longer SVL but are smaller as a proportion of SVLmax than for smaller species. Clutch sizes are larger and more variable for larger species; however, clutch sizes for larger species relative to SVLmax are smaller than for smaller species. The intraspecific influence of maternal SVL on clutch size is greater than the interspecific influence of SVLmax on clutch size. These results suggest there are greater fitness advantages for smaller species having relatively larger offspring than for larger species, which concurs with results for snakes and other genera of lizards, as well as optimal offspring size theory. Reproductive output also appears to be influenced by maternal abdominal volume. Analysis of phylogenetically corrected data generally concurs with patterns evident in the nonphylogenetically corrected data. Body size has a much greater influence on reproductive output of Varanus than phylogeny.
A New species of marsupial frog, Gastrotheca, with prominent cranial crests is described from humid montane forest on the eastern slopes of the Andes in Departmento de Pasco, Peru. The frog ahs an exceedingly robust cranium that most closely resembles that of G. cornuta; however, the cranial crests of G. cornuta are less well developed, and less obvious externally, than those of the new taxon. Within the genus Gastrotheca, one of the most variable parts of the skull is the squamosal, which has a variety of articular arrangements with the maxilla, the pterygoid, and in some taxa, the frontoparietal. In contrast to the modifications of dermal cranial elements, the postcranial skeleton seems to be relatively conserved in Gastrotheca.
Examination of the range-wide variation in 13 morphological characters, of biology, of color pattern and three anatomical features of the redfin and the grass pickerels showed them to be subspecifically distinct. For each of these subspecies, Esox a. americanus Gmelin and E. a. vermiculatus LeSueur, there are areas within which values for various characters are uniform and these areas delineate their ranges along the Atlantic coast and in the Mississippi River-Great Lakes watersheds. They do, however, intergrade across a broad front in the Gulf of Mexico region from the St. Johns River in Florida, to the Biloxi River, Mississippi. In this region it is impossible to assign individuals to either form. Over the areas of uniformity, the forms can be distinguished on the basis of two snout proportions, two scale characteristics, and, probably, color in young. Values overlap for other characters studied. The synonymy is reviewed and details of distribution are given.
Larvae of nine Atlantic and three eastern Pacific anthiines are described, redescribed or commented upon. Larvae of American Anthiinae exhibit various patterns of ornamentation, pigmentation and squamation that are described in detail and discussed in terms of their taxonomic value. Pigmentation of the dorsal portion of the trunk is most useful in distinguishing species. Information from cladistic analysis of larval and adult morphology suggests changes in our concepts of relationships among Alantic and eastern Pacific Anthiinae. Anthias tenuis and A. salmopunctatus are sister species and differ from other Atlantic species of Anthias in several aspects of larval and adult morphology; these two species need a new generic name or generic reassignment. Holanthias martinicensis is reassigned to Pronotogrammus Gill on the basis of larval and adult morphology. Pronotogrammus aureorubens, P. eos and Hemanthias vivanus are considered congeners on the basis of larval morphology; they each need a new generic name or generic reassignment.
Bufonid toads possess toxic compounds during most phases of their life cycle that render them unpalatable to many predators. However, snakes of several genera, including Thamnophis, frequently feed on toads and are apparently resistant to their toxins. When approached by garter snakes (T. s. sirtalis), toads (Bufo a. americanus) crouch and usually become immobile; visual stimuli are required to elicit these responses. Toads contacted by the main trunk (body) of a snake usually remain immobile and thus undetected by the snake; toads contacted by the head of a snake usually respond by hopping away and crouching again. The survival rates of toads exhibiting the species-typical response (i.e., hopping when contacted by the head of a snake and remaining immobile when contacted by the body of a snake) are significantly higher than those that respond with the alternative behavior.
Three new species of Phrynopus (Anura: Leptodactylidae) are described from cloud forest and puna habitats in central Peruvian Departamento de Pasco between 3600 and 4390 m elevation, the latter is the highest known elevation of the genus. The new species have first finger shorter than second, vomerine teeth absent, and tympanic membrane and tympanic annulus absent, but differ in snout-vent length, skin texture, and coloration. Currently 37 species of Phrynopus are described, 26 (70.3%) of which are endemic to Peru.
How climate change may affect parasite–host assemblages and emerging infectious diseases is an important question in amphibian decline research. We present data supporting a link between periods of unusually warm summer water temperatures during 2006 and 2008 in a northern California river, outbreaks of the parasitic copepod Lernaea cyprinacea, and malformations in tadpoles and young of the year Foothill Yellow-legged Frogs (Rana boylii). Relative to baseline data gathered since 1989, both 2006 and 2008 had significantly longer periods when daily mean water temperatures exceeded 20°C compared to years without copepod outbreaks. Infestation varied spatially in the watershed, as prevalence increased concomitantly with temperature along a 5.2 km longitudinal transect. At breeding sites of R. boylii with copepods in 2006, infestation ranged from 2.9% of individuals upstream to 58.3% downstream. In 2008, copepods were absent from the most upstream sites and infested up to 28.6% of individuals sampled at downstream locations. Copepods most frequently embedded near a hind limb or the cloaca. Among individuals with parasites in 2006, 26.5% had morphological abnormalities compared to 1.1% of un-infested individuals. In 2008 when the infestation peak occurred late in development (post Gosner stage 39), abnormalities were not associated with copepod infestation. In both years, recently metamorphosed frogs with copepods were, on average, slightly smaller than those not infested. These occurrences represent a sudden increase in local prevalence atypical for this river ecosystem. Previously we had only once seen copepods on amphibians (on non-native Bullfrogs, Rana catesbeiana), six km further downstream. Pacific Chorus Frogs, Pseudacris regilla, which co-occur with R. boylii in shallow near shore habitats were not used as hosts. The data suggest that increasing summer water temperatures, decreased daily discharge, or a combination of both, promote outbreaks of this non-native parasite on an indigenous host, and could present a threat to the long-term conservation of R. boylii under the flow regime scenarios predicted by climate change models.
Through its emphasis on recent research, its many summary tables, and its bibliography of more than 4,000 entries, this first modern, synthetic treatment of comparative amphibian environmental physiology emerges as the definitive reference for the field. Forty internationally respected experts review the primary data, examine current research trends, and identify productive avenues for future research.
South American gymnotiform. electric fishes exhibit sexual dimorphism of shape within species, and divergence of shape among species. Recent collecting in floating vegetation mats near Manaus, Brazil, yielded a remarkable association of female and "normal" males of Apteronotus hasemani plus a series of sexually mature male specimens with greatly hypertrophied snouts and gapes. We argue that these fish represent a single species based on shared distinctive features of morphology and coloration, continuous variation of morphometric characters including allometric and dimorphic facial growth in males, ecological and possible reproductive association, and identity in 16S mt rDNA sequences. The degree of dimorphism shown by the large males greatly exceeds previously known limits of intraspecific variation for A. hasemani. The males with the most extreme snouts and gapes closely approach the holotype of Apteronotus anas that is also a mature male. We conclude that A. anas is based on a large male of A. hasenzan, the older-named A. hasemani is the senior synonym.
Several aspects of vision in juvenile and adult Green Turtles (Chelonia mydas) are examined, with special reference to retinal anatomy such as oil droplet topography, transmission electron microscopy of photoreceptors, spectral transmission measurements of the ocular media (cornea, lens, and vitreous humor), and measurements of focal length and optical sensitivity. A detailed study of the distribution of the different color classes of oil droplets shows that all oil droplets are found in high concentrations (> 1000 mm(-2)) in the central/temporal parts of the retina. Red oil droplets were the largest, followed by yellow and clear. Oil droplet size varied in different parts of the retina. On average, red oil droplets were found in fewer numbers compared to yellow and clear oil droplets. Two types of clear oil droplets were identified: those that fluoresced under UV illumination and those that did not. We found that the majority (78.5%) of colorless oil droplets fluoresced when viewed under UV light. Spectral transmission measurements of the ocular media show that wavelengths to approximately 325 run are transmitted. This may suggest ultraviolet (UV) vision in Green Turtles. The optical sensitivity of the Green Turtle eye was relatively low, suggesting an adaptation to high light intensities commonly experienced by this species.
We describe a new species of Pristimantis from a cloud forest at 2450-2800 m in the Cordillera Oriental in southern Ecuador (Zamora Chinchipe). The new species has a maximum snout-vent length of 17.9 mm (average SVL of 21 males = 12.3 mm ± 1.2, and of 19 females = 15.9 mm ± 1.3). This new species is the second smallest frog from Ecuador and smallest Pristimantis. Morphologically and phylogenetically, the new species is similar to P. caeruleonotus and P. colodactylus. It is distinguished from them and its congeners by its size, tuberculation, a distinct color pattern consisting of tan blotches on dorsum, spots on a brown venter, minute brown spots on anterior and posterior surfaces of the thighs, and other morphological features. Determination of small body size in frogs is discussed and meristic data of 40 minute frogs are compiled.
Two new species of Eleutherodactylus are described from the Cordillera Occidental in northern Peruvian departments of Ancash and La Libertad. The new species from La Libertad is assigned to the Eleutherodactylus orestes Group and inhabits puna at elevations of 3400–4010 m. The Eleutherodactylus orestes Group is redefined. The second new species is assigned to the Eleutherodactylus conspicillatus Group; it represents the southernmost species of Eleutherodactylus in the Cordillera Occidental of the Andes.
A new species of toad, Bufo chavin, is described from two localities (3010 and 3070 m) from the eastern Andean slopes of central Peru (Departamento de Huinuco, Provincia de Pachitea, Distrito de Chaglla)w here it occurs sympatrically with Bufos pinulosus. Bufo chavin is referred to the Bufo veraguensis group. The new species differs from all members of this group by having large, elevated, elongate glands on each forearm and tibia, two large, elevated, elongate glands on the outer dorsal margin of each foot and one small, elevated gland on the outer dorsal margin of each hand. Eggs are relatively large, yolky and unpigmented in the new species.
Two populations of Ascaphus truei from northern Idaho and southeastern Washington show numerous differences in body proportions and conform poorly with named subspecies. The coloration and pattern of adults and tadpoles from the two areas are distinctive. The life history is similar in the two areas, but differs from that described for populations on the Olympic Peninsula. Breeding occurs in early fall. Male secondary sexual characteristics are highly developed only during the breeding season. The egg-laying season extends from late June to early August; sperm are evidently retained by the female from breeding the previous fall. Eggs hatch in August and September. Larvae possess hind legs at the age of two years, but transformation is not completed until 3 years after hatching. The distribution of Ascaphus is restricted in the two areas but shows no apparent correlation with changes in habitat or predators.
The skink, Ctenotus taeniolatus, is unusual in that unlike many other temperate lizards it does not possess abdominal fat bodies but uses the tail as the major lipid store. Although some lipids are distributed throughout the carcass, this lipid remains unchanged throughout the year, while tail lipids show a distinct seasonal cycle associated with overwintering and reproduction. Proportionally, females store greater amounts of lipids than males, and both store more than juveniles. Liver weights and glycogen and lipid content of the liver also show seasonal cycles, although changes in glycogen and lipid content are not reflected in liver weight changes.
Eleven fish species were identified from Homestead Cave, Utah. The remains, concentrated in the lowest stratum of the deposit, were accumulated by owls between approximately 11,200 and 10,100 14C yr B.P. and likely represent fish associated with the final die-off of the Lake Bonneville fauna. Four of the species (Salvelinus confluentus, Prosopium abyssicola, Catostomus discobolus, Richardsonius balteatus) represent their first records for Lake Bonneville. The S. confluentus premaxilla is the first Quaternary specimen record for the genus in the Great Basin and suggests a southern range extension during the Pleistocene. The C. discobolus specimens represent the first fossil records for the subgenus Pantosteus in the Great Basin; their presence in Lake Bonneville documents a Pleistocene connection between two presently disjunct populations. The hyomandibulars of Prosopium gemmifer are different from Recent specimens in a pattern suggesting Holocene introgression with Prosopium spilonotus. The lack of Cottus echinatus and the presence of both Cottus bairdi and Cottus extensus may suggest the former species evolved in Utah Lake over the last approximately 10,000 yr B.P. The abundance of Catostomus ardens and the absence of Chasmistes liorus may reflect a restricted spatial distribution of the latter in Lake Bonneville. Journal Article
Similar morphology and confused historical taxonomy of Hybognathus hankinsoni (brassy minnow) and Hybognathus placitus (plains minnow) have made determination of their historic distributions and conservation status unclear in eastern Colorado basins. We developed logistic regression models from morphometric measurements to predict species identity of Hybognathus collections from Colorado and adjacent counties (n = 1154 specimens in 134 lots). A model based on orbit diameter, standard length, and eye position correctly predicted 98% of the specimens examined and 100% of the museum lots. Hybognathus hankinsoni have larger eyes centered on a horizontal line through the tip of the snout, whereas H. placitus have smaller eyes centered above the tip of the snout. The two species were historically sympatric in the Platte, Republican, and Smoky Hill River basins, whereas H. placitus was allopatric in the Arkansas River basin. The taxonomic characters defined here will allow accurate identification of future collections to determine the status of these native fishes.
Dissection and histological analyses revealed the swimbladder of Hemiramphus far and H. robustus to comprise a matrix of discrete, gas-filled vesicles of 1–6 mm in diameter. The vesicles are not richly vascular and no discrete capillary bed organs were found. The anterior and posterior ends of the swimbladder have asymmetric projections that extend rostrad and caudad, respectively. These projections and some surrounding fatty tissue contain what we term protovesicles, which have thick walls that we infer expand to become the thin-walled vesicles of the main vesicular swimbladder. Dissection of museum specimens of other species of Hemiramphus and Oxyporhamphus convexus confirmed the presence of a vesicular swimbladder. However, examination of museum specimens of other hemiramphids, including O. micropterus, and flyingfishes revealed only a simple sac-like swimbladder. Presence of this unusual swimbladder in two genera within the same family is indicative of a strong synapomorphy that, in conjunction with recent molecular data, suggests that Hemiramphus and Oxyporhamphus convexus are closely related.
Analysis of mtDNA sequence variation (2,548 bp from ND2, cytb, and part of the control region) indicates that the genus Cyprinodon began diverging in the Late Miocene from a common ancestor with Megupsilon, a monotypic genus on the Mesa del Norte of Mexico. The geographic pattern of mtDNA variation, with estimates of divergence time, suggests that by the end of the Miocene Cyprinodon occurred from the Atlantic Coast and West Indies to near the western margin of North America via ancestral Rio Grande and Colorado River systems. Phylogeographic structure within the major mtDNA complexes supports a variety of hypotheses from geology and previous phylogenetic analyses for Late Neogene connections among basins in southwestern North America now separated by formidable barriers to dispersal. Comparison of the mtDNA tree with previous phylogenetic inferences from allozymes indicates that reticulate evolution involving divergent lineages probably was important in the history of Cyprinodon.
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 cones and are tuned for maximum signal reliability when viewed against known backgrounds. The optimal positions of spectral sensitivity in a modeled dichromatic visual system are generally close to the sensitivities known for reef fish. Models also predict that both UV-sensitive and red-sensitive cone types are advantageous for a variety of tasks. UV-sensitive cones are known in some reef fish, red-sensitive cones have yet to be found. Labroid colors, which appear green or blue to us, may he matched to the far-red component of chlorophyll reflectance for camouflage. Red cave/hole dwelling reef fish are relatively poorly matched to the background they are often viewed against but this may be visually irrelevant. The model predicts that the task of distinguishing green algae from coral is optimized with a relatively long wavelength visual pigment pair. Herbivorous grazers whose visual pigments are known possess the longest sensitivities so far found. Labroid complex colors are highly contrasting complementary colors close up but combine, because of the spatial addition, which results from low visual resolution, at distance, to match background water colors remarkably well. Therefore, they are effective for simultaneous communication and camouflage.
"The merits of this work are many. A rigorous integration of phylogenetic hypotheses into studies of adaptation, adaptive radiation, and coevolution is absolutely necessary and can change dramatically our collective 'gestalt' about much in evolutionary biology. The authors advance and illustrate this thesis beautifully. The writing is often lucid, the examples are plentiful and diverse, and the juxtaposition of examples from different biological systems argues forcefully for the validity of the thesis. Many new insights are offered here, and the work is usually accessible to both the practiced phylogeneticist and the naive ecologist."âJoseph Travis, Florida State University "[Phylogeny, Ecology, and Behavior] presents its arguments forcefully and cogently, with ample . . .support. Brooks and McLennan conclude as they began, with the comment that evolution is a result, not a process, and that it is the result of an interaction of a variety of processes, environmental and historical. Evolutionary explanations must consider all these components, else they are incomplete. As Darwin's explanations of descent with modification integrated genealogical and ecological information, so must workers now incorporate historical and nonhistorical, and biological and nonbiological, processes in their evolutionary perspective."âMarvalee H. Wake, Bioscience "This book is well-written and thought-provoking, and should be read by those of us who do not routinely turn to phylogenetic analysis when investigating adaptation, evolutionary ecology and co-evolution."âMark R. MacNair, Journal of Natural History
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 (lambda(max)) of the rods varied from 477-502 nm and the lambda(max) 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 lambda(max)-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 blue sensitivity or green absorption peaks (> 500 nm). 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). Except for two unusual species with humor-limited eyes, Acanthocybium solandri (Scombridae) and the priacanthid fish, Heteropriacanthus cruentatus, the remainder had corneal-limited eyes. The wavelength at which 50% of the light was blocked (T50) was classified according to a system modified from Douglas and McGuigan (1989) as Type I, T50 < = 355 nm, (32 species); Type IIa, 355 < T50 < = 380 nm (30 species); Type IIb, 380 < T50 <= 405 nm (53 species) and Type III, T50 > 405 nm (84 species). Possession of UV-transmitting ocular media follows both taxonomic and functional lines and, if the ecology of the species is considered, is correlated with the short-wavelength visual pigments found in the species. Three types of short-wavelength vision in fishes are hypothesized: UV-sensitive, UV-specialized, and violet-specialized. UV-sensitive eyes lack UV blockers (Type I and IIa) and can sense UV light with the secondary absorption peak or beta peak of their longer wavelength visual pigments but do not possess specialized UV receptor cells and, therefore, probably lack UV hue discrimination. UV-specialized eyes allow transmission of UV light to the retina (Type I and IIa) and also possess UV-sensitive cone receptors with peak absorption between 300 and 400 nm. Given the appropriate perceptual mechanisms, these species could possess true UV-color vision and hue discrimination. Violet-specialized eyes extend into Type IIb eyes and possess violet-sensitive cone cells. UV-sensitive eyes are found throughout the fishes from at least two species of sharks to modern bony fishes. Eyes with specialized short-wavelength sensitivity are common in tropical reef fishes and must be taken into consideration when performing research involving the visual perception systems of these fishes. Because most glass and plastics are UV-opaque, great care must be taken to ensure that aquarium dividers, specimen holding containers, etc., are UV-transparent or at least to report the types of materials in use.
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.
Sex differences in seasonal timing include differences in hatch- or birth-date distribution and differences in the timing of migration or maturation such as protandrous arrival timing (PAT), which is early male arrival at breeding sites. I describe a novel form of protandrous arrival timing, as a sex difference in birth-date distribution in a live-bearing fish (Dwarf Perch, Micrometrus minimus). In this species, birth coincides with arrival at breeding sites because newborn males are sexually active. A series of samples of pregnant females and young of year was collected in Tomales Bay, CA. I analyzed the daily age record in otoliths to estimate the conception date of broods and the age that young-of-year individuals were born. Males were born at a younger age than females, as indicated by the daily age record and also by the predominance of females in broods from which some young had already been born, which was a common occurrence in pregnant females with older embryos. Sex ratio of broods varied with conception date such that early-season broods were predominantly male, possibly as a result of temperature-dependent sex determination. The combined effects of the sex difference in age at birth and seasonal shift in sex ratio were to shift the mean birth date of males relative to females by five days. The most likely ultimate explanation for PAT in the Dwarf Perch is that it arises from exploitation (scramble) competition for mating opportunities among recently-born young-of-year males.
Notropis melanostomus is described as a new species collected from quiet, backwater areas of Pond Creek and the Blackwater River of northwest Florida. Its pharyngeal tooth formula of 4-4 and high number of anal rays (10-12) makes it unique for Notropis, except for possible confusion with N. ortenburgeri, which exceeds its size and has 9-11 anal rays. Notropis melanostomus has thin, nearly embedded scales, a black peritoneum, numerous long gill rakers, large eyes, and a variable cephalic lateral line system. Although more abundant than its original scarcity indicated, its preferred habitat is rapidly being encroached by commercial and domestic development.
Riverine fishes may benefit from moving onto inundated floodplains and directly exploiting floodplain resources. Studies of floodplain ecology for smaller streams have focused primarily on how fishes benefit indirectly from flooding (e.g., cycling of allochthonous nutrients). In a second order, blackwater stream in southern Mississippi, more food was available for cherryfin shiners (Lythrurus roseipinnis) on an inundated floodplain than was available in the low water stream. The floodplain drift of prey items consisted of significantly higher densities of terrestrial arthropods (Collembola, terrestrial Acariformes) and aquatic organisms associated with floodplain pools (Oligochaeta, larval Chironomidae, Anomopoda). While on the floodplain, L. roseipinnis ate significantly more food and consumed a significantly different diet than did L. roseipinnis in the stream. The difference in diets between the two habitats was because of the predominance of a terrestrial arthropod (Collembola) in the diet of L. roseipinnis on the floodplain. These results demonstrate that fishes in small streams can directly exploit floodplain food resources of briefly inundated floodplains. If stream-floodplain connectivity is eliminated in small streams through anthropogenic activities (e.g., channelization, riparian destruction), then L. roseipinnis and other small stream fishes will have limited access to invertebrate food resources.
Like many species of amphibians, Boreal Toads (Bufo boreas boreas, Bufonidae) are declining throughout portions of their range. Recent efforts have focused on describing the ecology of this species, yet few studies have evaluated demographic characteristics that may influence the persistence of Boreal Toad populations. Because Boreal Toads often convey themselves down valleys via stream channels in some areas, we set upstream-facing hoop nets in early to late summer in several first- to third-order tributaries in two western Montana river basins to assess the sizes of individuals using streams and examine temporal and spatial variation in captures. We made 923 captures of juvenile and adult Boreal Toads. Adult females were up to 125 mm snout-vent length, whereas males never exceeded 105 mm. Females tended to be heavier than males and female weights were significantly more variable. Early-summer captures were dominated by juvenile toads <40 mm, late summer catches were largely of individuals >70 mm, and toads of intermediate size were rare throughout. In tributaries of one river basin, captures of toads were more widely distributed in late summer than in early summer, whereas in tributaries of the other basin catches were similarly distributed in both periods. We infer from these patterns that frequent and perhaps far-ranging movements by juveniles and adults are typical of Boreal Toads in this region. We contend that netting streams in summer represents a useful complement to breeding site surveys for understanding the demographics and distribution of Boreal Toads, and perhaps other non-breeding amphibians near streams.
Phylogenetic relationships were reconstructed using partial mitochondrial DNA sequence data for the cytochrome b gene among all nine described species of Brachyrhaphis and several members of the tribe Gambusiini. We included three of the more than 40 members of the genus Gambusia and Belonesox belimnus, the third, monotypic genus of the tribe Gambusiini. Xiphophorus malinche served as the outgroup. Phylogenetic trees were generated using maximum-parsimony, maximum-likelihood, and neighbor-joining analyses. Hypotheses of relationships withii the tribe and genus Brachyrhaphis made by previous authors were tested. The existence of a slim- and a deep-bodied clade within the monophyletic genus Brachyrhaphis was supported. Brachyrhaphis hariwegi is the basal member of the deep-bodied clade, whereas B. punctifer is the basal member of the slim-bodied clade.
Erythrocles taeniatus, a new species of emmelichthyid fish, is described from 36 specimens, 77-159 mm SL, taken by trawl southeast of New Caledonia in 300 m. It is distinguished from its closest known relative, E. scintillans, in having modally 12 dorsal soft rays, a slightly more elongate body (depth 3.45-4.1 in SL), shorter head (head length 3.25-3.45 in SL), and different life color (deep pink with a distinct red midlateral stripe).
Crotalus cerastes was predominantly nocturnal, while C. mitchelli was mainly diurnal in the spring and fall and nocturnal during the summer months from June to September. The normal activity range of C. mitchelli (18.8-39.3 C) was narrower than that of C. cerastes (13.6-40.8 C). The overall preferred body temperature (April to December) of C. mitchelli (31.2 C) was significantly higher than that of C. cerastes (25.8 C). By being active at different times of the day during some months of the year, competition between these two species is reduced.