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Color pattern changes in fishes can vary from nearly instantaneous changes to long term, developmental (ontogenetic) changes. Species-typical patterns of ontogenetic color change (OCC) can provide insight regarding the behavior, ecology, and evolution of a taxon. Observations performed on laboratory-reared Firemouth Cichlids, Thorichthys meeki, from hatching to age 205 days, revealed 16 dynamic color pattern elements. Color pattern changes were correlated with age, but a significantly better correlation was found with body size. Ontogenetic color change in the Firemouth Cichlid featured the expression of some transitory color pattern elements not found in adults, and several elements and their sequence of expression were similar to those previously described for other cichlid species.
The effect of natural selection acting upon correlated traits can alter mating success and relative fitness dramatically. Eastern Mosquitofish (Gambusia holbrooki) harbor a genetic body-pigmentation polymorphism where pigmentation color is associated with particular correlated traits. About ninety-nine percent of all males are silver and about one percent are melanic (or black spotted). Here we demonstrate that these pigmentation morphs also differ in correlated life-history traits that affect fitness. Melanic males are larger than silver males in nature, and larger than silver siblings in a controlled environment. Melanic males have relatively larger gonopodia (mating organ) than silver males and greater survival during conspecific competition. This is indicative of a genetic correlation between body color, body size, growth rate, and relative gonopodium size (after controlling for body size). Our past work demonstrates that melanic males also have much higher survival with predators. Thus, while a relatively larger gonopodium is said to result in a cost with respect to predation in two Gambusia species, in G. holbrooki the fitness effects of correlated traits appear to far outweigh this cost for melanic males.
The Mummichog, Fundulus heteroclitus, is a widely distributed fish that has been extensively researched in the southern portion of its range (south of Cape Cod, MA). During the summers of 2003 and 2004, we studied the reproductive ecology of F. heteroclitus in a northern population (Northeast Creek, Mount Desert Island, Maine). Our direct observations show that unlike more southern populations, northern F. heteroclitus spawns daily during its two-month spawning season, with no preference for spring tides over the entire season. However, within consecutive semidiurnal tides significantly more spawning was associated with the higher high tide. Spawning occurred on bare gravel and on mud associated with the grass Spartina patens. Spawning was highly promiscuous with males typically spawning in groups with females in very shallow water during receding tides. These temporal and spatial patterns of oviposition caused eggs to be deposited in a much broader range of habitats than in southern populations of this species. We present and evaluate critically several hypotheses that may explain the variation in spawning patterns observed in this species.
We studied the pattern of annual reproductive activity in the Andean dendrobatid frog Ranitomeya virolinensis by comparing age–sex structure of the population, morphology, and morphometry of gonad among months and between seasons. The focal population is found in a mountain habitat with a bimodal pattern of rains, which suggests a seasonal pattern of reproduction, as has been observed in other Neotropical frogs. Mature and reproductive females and males were collected during the entire year and their reproduction is continuous. Sexual maturity was reached in both sexes near 16.0 mm snout–vent length (SVL); females are significantly larger than males. The diameter of the ovary and of the largest follicles did not show significant differences among months or between seasons. Clutch size in all mature females was only one egg per oviposition event; however, the simultaneous presence of advanced vitellogenic follicles with the oviductal egg suggests that females produce several clutches with short inter-clutch intervals. Testes of all mature males had seminiferous tubules with cysts of all spermatogenic stages and free spermatozoa in the lumen in each month we sampled. The size of testes did not differ among months or between seasons. Therefore, the ability to produce ova and spermatozoa is continuous throughout the year in this species. Because juveniles in the smallest size classes were observed in all months, we assume that reproduction is continuous. The continuous reproductive activity of R. virolinensis is likely favored by its semi-terrestrial mode of reproduction, in an environment where direct resources for reproduction, such as moist ground for oviposition and phytotelmata for rearing tadpoles, are available despite a seasonal rainfall pattern.
Intrapopulation diet specializations may result from the use of different dietary items or foraging tactics by individuals within a single population. The damselfish, Dascyllus aruanus, is a highly site-attached coral reef fish living in size hierarchies among branched corals. The trophic niche width and feeding specialization of this species were explored using stable isotopes and stomach content analyses. Intra-group niche variation was mainly related to fish size. Within social groups, D. aruanus gradually shifted its foraging tactics according to size; smaller fish fed on benthic prey such as isopods and copepods, and the larger fish foraged in the water column on planktonic copepods and larger-sized prey. Group density was found to explain some variation in trophic niche characteristics; greater specialization on prey size was observed in the colony having the highest density. All members of the largest colony foraged more frequently in the water column. Knowing that planktonic copepods are more energy-rich than benthic ones, a positive group-size effect facilitating access to preferred prey is suggested. Group size and group density effects on trophic specialization did not have any impact on body condition, suggesting that the behavioral plasticity of D. aruanus in its foraging strategies permits compensation for the maintenance of body conditions.
The Common Kingsnake, Lampropeltis getula, is thought to be experiencing population declines in the southeastern portion of its geographic range. However, limited information exists regarding the natural history and habitat requirements of the species in this region. We conducted a radio-telemetry study to investigate habitat selection in L. getula at multiple scales in southwestern Georgia. At the home range scale, L. getula did not show habitat selection. However, at the study-area scale, L. getula selected for natural pine and hardwood forest types over other available habitats. At the microhabitat scale, L. getula were found in locations with more coarse woody debris and woody vegetation than random sites. Lampropeltis getula primarily used small mammal (Peromyscus spp.) burrows and stumpholes as below ground refuge sites. We demonstrate that habitat selection of L. getula is complex and occurs at multiple scales.
To assess long-term temporal trends in White Shark (Carcharadon carcharias) predation, and examine the relationship between C. carcharias and pinnipeds, we examined a 17-year (1988–2004) data set of daily shark attack surveys from Southeast Farallon Island (SEFI), California. We modeled within-season and among-year variation in the number of observed shark attacks at SEFI. Within-season, daily probability of attack was affected by hours of effort, date, tide height, and pinniped abundance. The seasonal peak in shark predation did not vary inter-annually. Daily probability of attack was positively correlated with pinniped abundance and negatively correlated with tide height. After controlling for within-season effects, 51% of annual variation in the number of observed shark attacks was explained by an inverse function of the abundance of Northern Elephant Seals (Mirounga angustirostris). The addition of shark abundance to the model did not significantly increase the model's descriptive power. This suggests a functional response where predation by C. carcharias increased with abundance of M. angustirostris, but plateaued once a critical density of M. angustirostris were available, either due to limitations of prey handling or satiation. We detected no temporal trend in annual number of observed shark attacks. Therefore, C. carcharias depends on M. angustirostris as a critical food source and will increase or decrease predation rates depending upon current seal populations.
Carotenoids are integumentary colorants that must be ingested by vertebrates to be used as colorants. In many studies of fish and birds, carotenoid color serves as an indicator of foraging success, nutritional state, or parasite load. The dewlap of male Brown Anoles (Norops sagrei) contains the carotenoid pigments lutein and zeaxanthin. We performed a two-factor experiment to determine the effects of nutritional stress and xanthophyll supplementation on male dewlap color in N. sagrei. We tested the hypotheses that dewlap color is dependent on access to carotenoids and good nutrition. Contrary to our predictions we found no significant differences among groups of anoles that were either supplemented or not supplemented with carotenoids. Similarly, post-experimental dewlap spectral variation did not differ significantly among groups that were provided a standard or reduced diet. These findings demonstrate that dewlap color of adult male Brown Anoles does not change in response to food access or carotenoid supplementation.
Blanchard's Cricket Frogs (Acris crepitans blanchardi) in the central portion of their range show minimal capacities for freezing tolerance and survive overwinter by using terrestrial hibernacula where they avoid freezing. However, frogs may exhibit greater freeze-tolerance capacity at high latitude range limits, where winter climate is more severe. We studied freezing tolerance, glucose mobilization during freezing, and hibernacula microclimates of cricket frogs in southeastern South Dakota, at the northwestern limit of their range. Cricket frogs from South Dakota generally survived freezing exposure at −1.5 to −2.5°C for 6-h periods (80% survival), but uniformly died when exposed to these same temperatures for 24-h freezing bouts. Hepatic glucose levels and phosphorylase a activities increased significantly during freezing, but hepatic glucose levels during freezing remained low, only reaching levels approximating those prior to freezing in freeze-tolerant species. Moreover, muscle glucose and hepatic glycogen levels did not vary with freezing, suggesting little mobilization of glucose from hepatic glycogen stores during freezing, contrasting with patterns in freeze-tolerant frogs. Temperatures in soil cracks and burrows potentially used for hibernacula were variable, with some sites remaining above the freezing point of the body fluids throughout the winter, some sites dropping below the freezing point for only short periods, and some sites dropping below the freezing point for extended periods. These data suggest that cricket frogs in South Dakota, as in other portions of their range, survive overwinter by locating hibernacula that prevent freezing, although their toleration of short freezing bouts may expand the range of suitable hibernacula. These data also suggest that overwinter mortality may be high at the northern range boundary and might limit cricket frogs from expanding their range northward.
We describe Contia longicaudae, a new colubroid snake from California and Oregon, USA. Because C. longicaudae differs only subtly from the nominate species, C. tenuis, it has long been overlooked. However, genetic and morphological data readily distinguish C. longicaudae as distinct from C. tenuis. Contia longicaudae is genetically cohesive, possesses a greater number of caudal scales, a proportionately longer tail, and tends to be larger overall with more pronounced dorso-lateral stripes and a more muted ventral coloration than C. tenuis. Contia longicaudae also occurs in more mesic and well-shaded habitats than C. tenuis. Both forms appear to be broadly parapatric throughout much of northwestern California, and a few areas of sympatry have already been identified, particularly in southwestern Oregon, but the two species have not yet been found syntopically. Our data also reveal additional structure within C. tenuis; populations from the southern Sierra Nevada Mountains form an incipient lineage that warrants further investigation. The genetic and morphological subdivisions identified here allow future evolutionary and ecological studies, and conservations efforts, to focus on distinct evolutionary units within Contia.
Oryzias woworae, a new species of ricefish, is described from a freshwater habitat on Muna Island off the southeastern coast of the main island of Sulawesi, Indonesia. The new species is distinguished from all other known ricefishes by a remarkable color pattern of both sexes in life: the ventral surface of head and body anterior to the pelvic fins, dorsal portion of pectoral fins, dorsal-fin base, posterior portion of anal-fin base, caudal peduncle, and dorsal and ventral portions of caudal fin are brilliant red; the midlateral scales from just posterior to the eye to the caudal-fin base and the body scales anterior to the anal fin and ventral to midlateral scales are steel blue; the blue coloration is most prominent in adult males. Oryzias woworae, the smallest known ricefish from Sulawesi, is hypothesized to be a member of an unnamed clade of ricefishes diagnosed by a truncate, rather than lunate or emarginate, caudal fin. Description of O. woworae brings the recognized number of species in the beloniform family Adrianichthyidae to 29, 13 of which are endemic to Sulawesi. Ricefishes, in particular the new species, may serve as icons to generate interest in conservation of the endemic freshwater biota of Sulawesi.
Oryzias woworae, jenis baru ikan padi dideskripsi dari perairan Pulau Muna, perairan pantai Sulawesi Tenggara, Indonesia. Ikan jenis baru ini dapat dengan mudah dibedakan dari jenis yang telah dikenal sebelumnya, dari pola warnanya yang sangat menyolok. Ikan jantan maupun betina berwarna merah cerah dari kepala bagian bawah, tubuh depan bagian bawah sampai sirip perut, sirip dada bagian atas, pangkal sirip punggung, pangkal sirip anal bagian belakang, batang ekor, pangkal sirip ekor bagian atas dan bawah; warna biru terang dijumpai pada sisik tepat dibelakang mata, sisik pada pertengahan bagian tubuh sampai pangkal sirip ekor dan sisik didepan sirip anal dan sirip perut sampai sisik tengah tubuhnya; warna biru ini sangat jelas terlihat pada jantan dewasa. Oryzias woworae, jenis ikan padi terkecil dari Sulawesi diperkirakan merupakan anggota dari grup yang belum bernama, bercirikan sirip ekor yang bentuknya lebih cenderung bersegi dari pada bulan sabit ataupun agak cekung. Deskripsi Oryzias woworae menyebabkan jumlah species dari ordo Beloniformes, famili Adrianichthyidae menjadi 29, 13 diantaranya jenis endemik Sulawesi. Ikan padi, terutama jenis baru ini memberikan makna pentingnya konservasi dari biota endemik perairan tawar Sulawesi.
Loricaria birindellii, new species, is described based on two specimens from the Rio Curuá, a tributary of the Rio Iriri in the lower Xingu basin of Brazil. In adults the new species is distinguished from all other congeners by having a combination of an elongate dorsal-fin spine (36.0% SL, based on the holotype vs. 16–29%, usually less than 26% SL) that is supported throughout most of its length by the first branched ray, and an inconspicuous (vs. prominent) post-orbital notch with minimum orbital diameter 95.4–97.2% (vs. 71.8–91.5%) of maximum orbital diameter. It is further distinguished from similar and geographically proximate species, L. lata and L. simillima, by having a more slender body, particularly head width (13.9–14.9% SL vs. 15.2–19.4% SL in L. simillima and 16.4–20.1% SL in L. lata). The larger specimen of L. birindellii exhibits male breeding characteristics known in other species of Loricaria, including expanded membranous portions of the lower lip, an increase in development of globular papillae on lip surfaces, rounded premaxillary- and dentary-tooth cusps, and slight thickening of the pectoral spine. The smaller specimen of L. birindellii exhibits a different caudal fin pigment pattern and lacks an elongate dorsal spine, suggesting that the species either undergoes ontogenetic transformation or exhibits sexual dimorphism in these characters. Two juvenile specimens (95.6 and 98.0 mm SL) from the Rio das Mortes (Araguaia-Tocantins basin) are tentatively regarded as L. aff. birindellii, based on shared morphological characters and geographic proximity.
Bedotia alveyi, a new species of Malagasy rainbowfish, is described from the lower reaches of the Antainambalana and Vohimaro rivers and their tributaries near the village of Maroansetra in the Makira Forest Protected Area, northeastern Madagascar. The new species is distinguished from congeners by the presence of a distinctive crescent-shaped to semicircular spangle on the posterior half of many opercular and flank scales, which creates iridescent golden (occasionally whitish to bluish) highlights. Additional unique pigmentation pattern features include a dark midlateral stripe interrupted by sparse lateral blotching and rust-red caudal-fin lobes. Bedotia alveyi is one of several new species that were collected during a brief expedition into the Makira Forest region in 2003. The Makira Forest was designated a Malagasy protected area in December of 2005.
A new species of the thorny catfish genus Leptodoras (family Doradidae) is described. The new species shares three characters with its congeners, the modified oral hood with distinct upper labial extensions, the first gill arch with enlarged accessory lamellae extending well onto medial face of gill filaments, and the pelvic fin inserted in anterior half of body. The new species is distinguished from congeners by having a large dark submarginal blotch on distal half of dorsal-fin spine and anteriormost dorsal-fin branched rays, lower labial extension of modified oral hood extending more posteriorly than upper labial extension, relatively few midlateral scutes, gas bladder moderately sized (not reduced), paired bony capsules on anteriormost vertebrae reduced to paired cup-like laminar ossifications separated by a triangular septum, pair of small, swelling-like diverticula on each side of the anterior chamber of gas bladder, a well-developed anterior nuchal plate, and nuchal foramina present. The new species was discovered from a single specimen collected in the rio Fresco, a tributary of the rio Xingu, and is described based on this and on additional material recently collected in the same area. A discussion of its placement within Leptodoras is also presented.
Uma nova espécie de botoado do gênero Leptodoras (família Doradidae) é descrita. A nova espécie compartilha três caracteres com seus congêneres: capuz oral modificado, com extensão do lábio superior, primeiro arco branquial com lamelas acessórias bem desenvolvidas estendidas sobre a face medial dos filamentos branquiais e a nadadeira pélvica inserida na parte anterior do corpo. A nova espécie difere das congêneres por ter uma mancha escura submarginal na metade distal dos raios anteriores da nadadeira dorsal, capuz oral com extenção do lábio inferior mais posterior do que a do lábio superior, relativamente poucos escudos laterais, bexiga natatória de tamanho moderado (não reduzida), cápsulas ósseas pares sobre as vértebras anteriores reduzidas a um par de ossificações laminares em formato de cuia separadas por septo triangular, um par de divertículos diminutos em cada lado da câmera anterior da bexiga natatória, placa nucal anterior bem desenvolvida e forame nucal presente. A nova espécie foi descoberta a partir de um único exemplar coletado no rio Fresco, tributário do rio Xingu, e é descrita com base neste e em exemplares adicionais recentemente coletados na mesma área. Uma discussão da posição filogenética da nova espécie entre as congêneres é apresentada.
Populations of Campostoma (until now assigned to C. anomalum pullum) in parts of eastern Oklahoma and western Arkansas exhibit striking red or red-orange coloration in median fins and, usually, in all paired fins. This coloration is most intense in summer months, although it is present during much of the rest of the year, and is found in individuals of all sizes and both sexes. Such coloration is not found in contiguous populations of nominal C. a. pullum, or in any other Campostoma species. In addition to the red fin coloration, a distinct tubercle pattern on the nape of nuptial males, a unique pattern of dark pigment on the caudal fin of nuptial adults, and a minor row of teeth on the pharyngeal arch support the recognition of this form as a distinct species. We resurrect Campostoma spadiceum (Girard, 1856) as the valid name for this species and propose the common name Highland Stoneroller. We document its taxonomic history, discuss a junior synonym (Dionda griseaGirard, 1858), and compare C. spadiceum morphologically to contiguous C. a. pullum populations and to other recognized taxa in the genus. The ranges of C. spadiceum and C. a. pullum are largely non-overlapping, and we have found no morphological evidence of syntopic occurrence.
The monotypic Indo-Pacific genus ParastromateusBleeker, 1864 is morphologically peculiar among carangid fishes in its overall body form and has been difficult to place phylogenetically. This has been partly the result of a lack of detailed morphological data for this and other carangid fishes. Here, we describe and analyze the osteology of Parastromateus niger (Bloch, 1795), review its taxonomic history, and describe characters that are suggestive of its phylogenetic affinities. In addition, we made a broad survey of gill-arch skeletal characters for carangids. Previous studies have noted that a combination of features from the skeletal anatomy of Parastromateus firmly places it within the Carangidae (presence of a gap between the second and third anal-fin spine) and within the tribe Carangini (presence of scutes, inferior vertebral formina). Within the Carangini, however, its phylogenetic placement is less clear. In our survey of the gill arches of Carangidae, we found that only Parastromateus and Hemicaranx have an enlarged toothplate that bridges the epibranchial 4–ceratobranchial 4 joint. Additionally, these two genera have a superficially similar form of teeth on the pharyngeal toothplates (elongate and filamentous vs. conical and stout in other carangins). Although outside the scope of our study, these and other morphological aspects of Parastromateus need to be brought into a broad-based cladistic analysis of the Carangidae.