The Amazonian lizard Anolis trachyderma was studied at three sites stretching from eastern Ecuador to the central Amazon of Brazil. These lizards occupy low vegetation and leaf litter microhabitats in well-shaded, damp rain forest. Their body temperatures are low (27.8 C on average) and only slightly higher than corresponding substrate and air. They are as likely to be active on cloudy as on sunny days but are usually found in shade. The diet is varied, but dominated volumetrically by grasshoppers-crickets, insect larvae-eggs-pupae, spiders, roaches, and lizard shed skin. Although dietary overlaps among populations are low, no significant differences in prey choice existed based on a randomization analysis. Locality-based and sexual variation in morphology was evident. Overall, A. trachyderma appears similar ecologically across a large portion of the Amazon. Comparisons with three ecologically similar anoles, Anolis nitens scypheus (sympatric with A. trachyderma) and Anolis humilis (no range overlap), reveal similar microhabitat use, body temperatures, and diets, but substantially different morphology. The ecomorph concept may not apply as well to mainland anoles as to island ones, possibly because taxonomically distant lizard species may have had a stronger historical effect on mainland anoles than on island species.

A phylogenetic hypothesis is presented illustrating relationships among 23 extant sturgeon species based on nucleotide data from five mitochondrial genes (cytochrome b, NADH5, control region, 16S, and 12S). The tree supports our previous hypotheses regarding relationships among species of Acipenser and Huso. The introduction of Scaphirhynchus and Pseudoscaphirhynchus to the analysis does not change these main relationships. The genera Scaphirhynchus and Pseudoscaphirhynchus do not form a monophyletic group corresponding to the subfamily Scaphirhynchinae or the tribe Scaphirhynchini. The genus Scaphirhynchus may be basal within the family Acipenseridae, whereas Pseudoscaphirhynchus appears to be embedded within Acipenser clustering with the stellate sturgeon, Acipenser stellatus. The morphological similarity between Scaphirhynchus and Pseudoscaphirhynchus could be a result of convergent evolution of different ancestral sturgeon forms in similar environmental conditions of distant river systems of North America and Central Asia.

The thermal and hydric environment during incubation of turtle eggs influences hatchling size, sex, energy reserves, and thus their quality. Information on the natural nest environment of flatback turtles (Natator depressus) is lacking. Therefore, the current study investigated the thermal and hydric environment of their nest chambers and nesting beach (at Peak Island, east coastal Queensland during the 1996/1997 and 1997/1998 nesting seasons). The temperature of nest chambers and the nesting beach showed temporal and spatial variation. Beach temperature increased through the nesting season as summer progressed and showed significant vertical and lateral variation. The temperature in the core of nest chambers increased as incubation progressed (on average 7 C) apparently because of both metabolic heating and the natural seasonal increase in sand temperature. The temperature range of nests was 25.5–36.5 C, with many nests exposed to temperatures above 35 C for extended periods. Water content of sand surrounding nest chambers at the beginning of incubation ranged from 2.6–7.8% (w/w), varying with date of laying and location on the beach. Natator depressus eggs may be more tolerant of high incubation temperatures and severe moisture stress than those of most other sea turtle species. Nest success was not influenced by the position of the nest on the beach but was positively related to clutch size. Neither nest success nor clutch size varied significantly between subsequent clutches of an individual female. Hatchling sex ratio at this beach possibly depends on the date of egg laying. Because high density nesting occurs when beach temperature appears to produce almost all female hatchlings, the hatchling sex ratio at Peak Island is likely to be biased toward females. Data gathered in the current study will assist in the development of management strategies to protect this endemic species.

The California grunion Leuresthes tenuis, a teleost fish (Atherinopsidae), spawns terrestrially by burying its eggs in damp sand on beaches following semilunar spring tides. The eggs incubate above the water line and are ready to hatch after approximately 10 days at 18 C. However, grunion eggs do not hatch, even when developmentally ready, until returned to water and mechanically stimulated by wave action. In nature, the environmental trigger occurs on subsequent semilunar tides, when waves reach as high on the shore as the eggs were buried during spawning. If waves do not reach the eggs after one semilunar tidal cycle, the eggs survive by extending incubation and delaying hatching until the trigger occurs. This may take up to several additional weeks. Temperature affects the time to hatching readiness in California grunion eggs; this interval is shorter at warmer temperatures than at cooler ones. We incubated grunion eggs at three relevant temperatures: 15, 20, and 25 C. Viability of embryos was ascertained by microscopic examination, and hatching was attempted daily for eggs from each temperature, until no eggs hatched. The ability to extend incubation and delay hatching decreased with increasing incubation temperature. At the coolest temperature, eggs survived longer but were not able to hatch at the time of the first semilunar spring tide series. Hatching success and the duration of extended incubation are also influenced by temperature. Eggs incubated at 15 C always had lower hatching success than eggs incubated at the two higher temperatures. Eggs incubated at 20 C had a significantly greater chance of surviving and hatching during the three subsequent semilunar tides than eggs at 15 or 25 C. Eggs incubated at higher temperatures matured more quickly but had a shorter total period of viability. Temperature affects the duration of extended incubation for grunion eggs, and influences their hatching success, yet a majority of the eggs can mature and hatch successfully at each of the three temperatures. A broad temperature tolerance, plasticity in incubation duration, and environmentally triggered hatching allow the grunion fish to spawn terrestrially over a long season in a variable coastal ecosystem.

Simply classifying a species as “arboreal” may tell us little about the ways that it uses above-ground habitats. For example, some species of arboreal snakes select exposed positions on branches, others lie among foliage, and yet others exploit crevices within the trunk. These different structural niches may involve fundamentally different patterns not only of habitat selection criteria but also of morphological, behavioral, and ecological traits. We implanted miniature radio-transmitters in 16 adult Stephens' banded snakes (Hoplocephalus stephensii) in a forest managed for timber production in northeastern New South Wales, and relocated these snakes regularly over a two-year period to clarify their patterns of habitat use. Unlike the vast majority of Australian elapid species, H. stephensii are primarily arboreal. Radio-tracked snakes were in trees on > 80% of observations, generally hidden within hollows. The snakes remained inactive in trees for three to five months during winter each year. Snakes in wet sclerophyll forest sometimes foraged in tall sedges, whereas snakes in rain forest spent little time on the ground. Attributes of 139 trees used by the snakes were compared with those of 1437 trees in randomly selected plots. Snakes selected old, large trees with many hollows or extensive vine cover. Except for being above ground, the retreat sites used by these arboreal elapids were structurally similar to those used by their terrestrial relatives. The tree attributes important to H. stephensii thus differ profoundly from those important to many other species of arboreal snakes.

We sampled fishes with a small trawl in the deep midchannel and with beach seines on nearby sandy beaches at five sites along two parallel headwater tributaries of the upper Amazon in Eastern Ecuador. We quantified ecological distance between fish assemblages of deep-river and beach habitats and compared assemblage composition, species richness, and diversity. Results of detrended correspondence analyses (DCA) and two-way indicator species analyses (TWINSPAN) clearly revealed the presence of a striking faunal change (i.e., about 92% dissimilarity) between beach-zone and off-shore fishes. The boundary between these assemblages occurred at about 2 m depth. Beach samples collected as far apart as 325 km were more similar to each other than to trawl samples taken only 10s of meters away. The beach-zone fish assemblage was strongly dominated by small characins, whereas the deep-river habitat was dominated by catfishes and weakly electric gymnotiforms. Apparent adaptations to deep-water habitats included small size, flattened or elongated body, ventral mouths, reduced eyes, and sensory specializations for life in what may be a nearly light-less environment (e.g., chemo- and electroreceptors). Visually oriented fishes and those dependent on algal or detrital foods were mostly absent from the deep-river samples. We caught many more species along the beaches, but after correcting for higher numbers of individuals collected in beach habitats, species richness was not noticeably different between the two habitats. Species diversity also averaged slightly higher for beach samples, but the difference was not significant. We infer that the deep-river habitat was undersampled and that further effort in the deep river would reveal the presence of many more species.

Two most widely distributed “subspecies” of the Desmognathus fuscus complex are the northern dusky salamander (Desmognathus fuscus fuscus) and the spotted dusky salamander (Desmognathus fuscus conanti). Previous mitochondrial DNA and allozyme studies of this complex have suggested that these two forms should be granted species-level recognition. However, detailed examination of populations inhabiting the region where the two taxa come into contact have not been performed to corroborate this taxonomic change. In this study, specimens were collected from four transects that traverse the putative contact zone. Allozyme and color pattern analysis were employed to determine the nature of variation across the area and evaluate the taxonomic status of D. f. conanti. Phylogenetic analyses of allozyme data divide the populations sampled into at least four major groups, two of which are referable to Desmognathus fuscus (groups A and C) and two referable to D. conanti (groups B and D). This study supports the distinctiveness of D. conanti by revealing parapatry between populations of groups A and B in western Kentucky with only a minor amount of hybridization between them and identifies color pattern differences that are effective for characterizing most group B individuals. The data presented here suggest that a longitudinal division may exist within D. conanti in central Alabama. Group C occurs primarily on the Piedmont of North Carolina and Virginia and appears to hybridize with group A in central Virginia. Groups C and D are treated, conservatively, as D. fuscus and D. conanti, respectively; but further study may reveal that each is a distinct species.

The relationships of Mustelus species in Australian and New Zealand waters were investigated by analysis of allozymes (28 loci), polymorphisms in the length of restriction fragments from mitochondrial DNA (mtDNA; whole genome, 10 restriction enzymes), and precaudal vertebrae counts. We confirm the existence of four Mustelus species in this region: a nonspotted Mustelus sp. A (a single specimen genetically examined from the North-West Shelf off Western Australia), and three spotted species—M. sp. B (from Western Australia, the North-West Shelf south to Perth—extending its known range); Mustelus antarcticus (from Bunbury in Western Australia around the southern Australian coast and as far north as Townsville, Queensland), and M. lenticulatus from New Zealand. Mustelus sp. A was the most divergent of these species, with fixed differences at six allozyme loci and a unique mtDNA profile in digests with six of the 10 restriction enzymes. The other species were much more similar to each other, with no completely fixed differences detected at any of the allozyme loci assayed. Mustelus sp. B differed very significantly from M. antarcticus in allele frequencies for three allozyme loci, and one restriction enzyme gave a unique mtDNA profile. Mustelus lenticulatus was distinguished from M. antarcticus by significant frequency differences at nine allozyme loci, and two restriction enzymes were nearly diagnostic. MtDNA nucleotide diversity (average 0.0323) and nucleotide divergence (average 0.0315) between species was low. Allozyme variation in M. antarcticus was high (H = 0.100) but low for the other three species (M. sp. A = 0.000; M. sp. B = 0.025; M. lenticulatus = 0.019). Mustelus antarcticus also had the highest mtDNA haplotype diversity of 0.534 (± 0.022); M. sp. B had 0.385 (± 0.149), and M. lenticulatus had 0.000 (this parameter could not be estimated for M. sp. A because only a single specimen was genetically examined). The within-species nucleotide diversities showed a higher value for M. sp. B (0.0021) than for M. antarcticus (0.0014). Significant differences between species were also observed for precaudal vertebrae counts. These are lowest in M. sp. B (77.39 ± 2.79), followed by M. antarcticus (85.61 ± 4.03), M. sp. A (90.50 ± 1.05), and M. lenticulatus (94.88 ± 1.46).

The embryos and larvae of the Australian moss frog Bryobatrachus nimbus develop for over one year in concealed cavities within bryophytes or lichens. Oviposition occurs in drier summer months, and consequently embryos experience a variety of hydrous conditions in concert with the drying and rehydration of the nest material. When the hydrous environment was manipulated in the laboratory, B. nimbus embryos incubated in the wettest conditions (0 kPa) had significantly higher survival to hatching than embryos reared at three drier water potentials −5 −10 and, −25 kPa). Moreover, embryos incubated in drier conditions developed with pronounced trunk and hind limb-bud asymmetry and had significantly shorter and shallower tails and lower metabolic rates, relative to embryos incubated at 0 kPa. Measurement of capsule morphology showed that the volume of perivitelline fluid in −10 and −25 kPa embryos was only 9% of that bathing 0 kPa embryos. The reduced developmental space, coupled with adhesions between the yolk sac wall and perivitelline membrane, limited rotation of drier embryos and, hence, promoted asymmetric development. The severity of abnormalities at −25 kPa indicated that B. nimbus was less tolerant of low water potentials than other anuran species studied. The unusually large egg capsules of B. nimbus buffer embryos against water loss during intermittent dry periods, but the vegetative nest material must also provide appreciable protection from egg desiccation during natural incubation.

The armored catfish genus Oxyropsis is diagnosed as a monophyletic assemblage of three species of the family Loricariidae on the basis of presence of a single row of enlarged odontodes along the trunk midline lying adjacent, and immediately dorsal to, the lateral line canal. Oxyropsis is here resurrected from synonymy with Hypoptopoma Günther (1868) and three species, distributed in the middle and upper Amazon, Negro, and Orinoco basins of South America, are diagnosed and redescribed. The type species, Oxyropsis wrightiana Eigenmann and Eigenmann (1889), occurs in the upper Amazon and lower Ucayali River basins and is diagnosed among congeners by the presence of seven ultimate median series trunk plates, which are progressively smaller and narrower than the immediately preceding plates, and by pectoral spine serrae either extremely reduced in size (height less than one-sixth of the spine width) or absent. Oxyropsis carinata (Steindachner, 1879) occurs in the middle and upper Amazon River basin and is diagnosed by the presence of three or four ultimate plates of the median series distinctly narrower than preceding plates, pectoral spine serrae well developed both in size (tooth height approximately one-fifth of the spine width) and extent along the spine shaft and by greater numbers of teeth. Oxyropsis acutirostra Ribeiro (1951) occurs in the Negro and upper Orinoco basins and is diagnosed by the presence of a truncated median plate series, plates not extending to the caudal fin base and fewer teeth. Its holotype is presumed lost. Among Oxyropsis species, caudal peduncle depression covaries with standard length and degree of median plate series reduction. This observation, coupled with intrinsic differences in the association of related features among loricariids, further supports the hypothesis that trunk depression and caudal peduncle elongation have coevolved multiple times within the Loricariidae.

Two species of plethodontid salamanders (Plethodon cinereus and Plethodon hoffmani) exhibit character displacement with respect to body size and head morphology in Pennsylvania. In areas of allopatry, the two species do not differ in these traits while in an area of sympatry, P. cinereus is smaller (and eats smaller prey) and P. hoffmani is larger (and eats larger prey) in body size and head morphology. We tested the hypothesis that this form of character displacement is a consequence of alpha selection, in which natural selection favors increased aggression of sympatric species relative to their allopatric conspecifics. We found little evidence that allomonal response to or aggressive behavior toward heterospecifics differed significantly between allopatric and sympatric populations of either P. cinereus or P. hoffmani. Thus our data do not support the hypothesis of alpha selection shaping the morphology of the two species in sympatry. However, we found that both allopatric and sympatric populations of P. cinereus were significantly more aggressive and significantly less submissive than either allopatric or sympatric populations of P. hoffmani. These results suggest either of two conflicting interpretations concerning interspecific competition between the two species. First, the boundary of contact between the two species is static because although P. cinereus is aggressively superior, P. hoffmani is exploitatively superior (eats larger prey) in competition in areas of sympatry. Alternatively, P. cinereus is slowly encroaching on the geographic distribution of P. hoffmani because the former species is not only aggressively superior but also exploitatively superior (eats the more profitable, although smaller, soft-bodied prey types). Our results also support inferences drawn from previous research that P. cinereus competes strongly when geographically in contact with other confamilial species (e.g., Plethodon hubrichti, Plethodon shenandoah, juveniles of Plethodon glutinosus, and Eurycea cirrigera).

The loricariid genus Pogonopoma Regan, 1904, is revised and expanded to include Pogonopomoides parahybae and a new species, Pogonopoma obscurum, from the upper rio Uruguai, southern Brazil. The new species can be distinguished from its congeners by having eight to 11 branched dorsal fin rays, versus seven in the remaining species. The phylogenetic placement and geographic distribution of the new species are evaluated and discussed. An identification key for the genera of the Rhinelepis group of the subfamily Hypostominae and for the species of Pogonopoma is provided.

Ornate box turtles, from the Sand Hills of Nebraska, live in a habitat characterized by slopes, a fine sand substrate, and temperatures that can vary greatly, both diurnally and seasonally. We examined the locomotor responses of these turtles to slope, substrate, and temperature. Only 25% of the turtles could successfully walk on slopes as steep as −40°. They were better at walking upslope, but their speed progressively decreased as slope increased. As grade increased, they primarily adjusted stride frequency on upslopes but stride length on downslopes. Turtles appear to be much more affected by slopes than are lizards. Speed was significantly reduced on sand substrates in comparison to Styrofoam, and this was primarily because of a reduction in effective stride length. Speed increased with increasing temperature from 20 to 35 C, almost entirely resulting from an increase in stride frequency; however, the Q₁₀ for locomotor performance was low. Turtle speeds in the field averaged 0.05 m/s, and, although there was a tendency for higher speeds at higher operative environmental temperatures, this was not statistically significant. Within their natural Sand Hill habitat, these turtles are often active under conditions of slope, substrate, and temperature that are suboptimal for locomotion. However, locomotor performance is not adversely affected to any appreciable degree by the potential constraints of their habitat.

The New World labrisomid genus Paraclinus comprises small, cryptic reef fishes and is represented by three endemic species on the coast of Brazil. Paraclinus rubicundus (Starks) occurs from Alagoas south to Santa Catarina and is removed from the synonymy of its Caribbean counterpart Paraclinus nigripinnis (Steindachner), from which it is separated by its lower numbers of dorsal fin spines, lateral line scales, and rows of scales on the pectoral fin base. The two remaining species were also historically misidentified as Caribbean forms. Paraclinus arcanus n. sp., known from Pernambuco south to Rio de Janeiro, is distinguished from the Caribbean Paraclinus fasciatus (Steindachner), by its higher numbers of dorsal fin spines, nuchal cirrus morphology and the presence of a scaleless area along the anterior portion of the dorsal fin base. Paraclinus spectator n. sp., known from Rio de Janeiro south to Santa Catarina, is distinguished from other large Paraclinus with an elongate first dorsal spine and three segmented pelvic fin rays by the combined presence of a flattened, triangular opercular spine and a soft ray as the last dorsal fin element.

Hyphessobrycon heliacus n. sp. is described from the upper rio Tapajós basin, Mato Grosso, Brazil. The new species is distinguished from other currently recognized Hyphessobrycon species by the combination of an enlarged caudal spot, the golden body coloration in life, the elongate filamentous dorsal and pelvic fins, thickened anal fin rays, and the absence of anal fin lobe. These last three characteristics are present only in mature males.

Halaphritis platycephala, a new genus and species of the perciform suborder Notothenioidei, is described from coastal reef habitats of temperate Australia. It is a rarely seen, cryptic, nocturnal species that lives deeply concealed in crevices and caves during the day. In external appearance, Halaphritis superficially resembles the parapatric, monotypic pseudaphritid, Pseudaphritis urvillii (Valenciennes), an estuarine and freshwater species that is among the most primitive extant notothenioid fishes. Based on osteology, dentition, and fin and sensory canal structures, Halaphritis is provisionally included in the temperate marine family Bovichtidae. In addition to its unique character mix, Halaphritis can be distinguished from confamilial genera by having a rounded caudal fin, unbranched pectoral fin rays and strongly protruding, dorsally directed eyes. The endemic coexistence of possibly the two most primitive icefish genera in cool temperate Australian seas is supportive of a Gondwanan linkage, specifically an Australian/eastern Antarctic origin of the suborder. Current inclusion of the primitive family Bovichtidae in the suborder has been challenged on molecular grounds but a search for fresh tissue of Halaphritis to confirm its position within the basal notothenioids has so far proven unsuccessful.

A new species of clingfish (Gobiesocidae) in the genus Rimicola, that exhibits unique sexual dimorphisms, is described from the Santa Barbara Islands, California. It is most closely related to two other California Rimicola species that are also sexually dimorphic. Now that a Rimicola species described from the Caribbean has been determined to belong elsewhere, the genus reverts to its original status as a northeastern Pacific endemic.

We tested for predator-induced plasticity in development and growth of embryos and young tadpoles of green frogs (Rana clamitans). We expected to observe developmental plasticity in response to the leech, Macrobdella decora, because the leech represents a high, but unpredictable, risk of mortality. Embryos raised with a leech tended to delay hatching and hatched at larger size. Young tadpoles raised with a leech grew more slowly than tadpoles raised without a leech. Such changes should enhance survival of green frogs faced with the threat of leech predation.

The Missouri saddled darter, Etheostoma tetrazonum, is endemic to the state of Missouri where it inhabits medium to large creeks and streams in the Ozark region. Two morphologically distinct forms of the species have been identified on the basis of color pattern in breeding males, one form restricted to the Meramec River drainage and another found in the Gasconade, Osage, and Moreau River drainages. Given the rather striking differences in color pattern, a molecular character set was assembled to determine the extent of genetic variation between these two forms and whether additional drainage specific patterns of divergence were present. Complete cytochrome b (cyt b) sequences were obtained from 36 individuals of E. tetrazonum representing 13 populations from throughout its range. Phylogenetic analysis of these data resulted in two, well-supported monophyletic groups within E. tetrazonum: one consisting of individuals from the Meramec River drainage and the other consisting of individuals from the Moreau, Osage, and Gasconade River drainages. These findings are consistent with the recognition of two species: one species from the Moreau, Osage, and Gasconade River drainages, and one restricted to the Meramec River drainage.

Intrasexual variation in courtship behavior is common but the potential for such variation within turtles has not been considered. Forty-seven behavioral trials with wild-captured slider turtles (Trachemys scripta) were conducted throughout the local season of activity for this species (April–October). The frequency of occurrence, seasonality, and directionality of courtship behaviors (i.e., biting, chasing, and titillation) performed by melanistic and nonmelanistic males were examined. I tested the hypotheses that the expression of these behaviors during the mating season (late August to mid-October) would differ between melanistic and nonmelanistic male T. scripta and that melanistic and nonmelanistic males would differ with respect to their precopulatory display rates. Biting, chasing, and titillation directed toward females by melanistic and nonmelanistic male T. scripta during the mating season were significantly different. Courtship behaviors (i.e., precopulatory displays) were not always performed prior to copulation attempts and melanistic males performed courtship behaviors prior to such attempts more frequently than did nonmelanistic males. These differences may represent a conditional strategy involving size-dependent alternative mating tactics with larger melanistic males adopting tactics that involve a greater precopulatory display rate coupled with biting and chasing behaviors. The smaller nonmelanistic males adopt tactics that involve titillation behaviors and a lower precopulatory display rate.

We measured resting routine oxygen consumption rates (MO₂, in mg O₂ · h⁻¹ · kg^−0.67) of bat rays (Myliobatis californica) under two seawater (33, 35 ppt) and two brackish (15, 25 ppt) salinity conditions. A significant increase in MO₂ was observed for rays in 15 and 25 ppt brackish water, compared with those in 33 or 35 ppt, presumably due to increased osmoregulatory costs. Our results suggest that energetic factors associated with seasonal decreases in salinity may influence the out-migration of bat rays from Tomales Bay (California) during the winter months.

The use of a magnetic compass plays a significant role in the daily and seasonal movements of numerous organisms; however among amphibians, magnetic compass orientation has been convincingly demonstrated only in eastern red-spotted newts, Notophthalmus viridescens, with some indirect evidence coming from several species of bufonid toads. In this study, larval bullfrogs, Rana catesbeiana, were trained in outdoor tanks with two different Y-axis (shore/deep water) directions and then tested in an indoor arena in one of four symmetrical alignments of an earth-strength magnetic field. The tadpoles oriented bimodally along the correct magnetic direction of the Y-axis experienced during training, demonstrating that this anuran species is able to learn and orient along the Y-axis by sensing the geomagnetic field.

We studied the feeding ecology of juvenile lumpsuckers, Cyclopterus lumpus, during their first year in natural floating seaweed clumps and experimental floating seaweed branches, in southwest Iceland. The juveniles appeared to ignore sessile, slow-moving, and small animals (e.g., ostracods, bivalves, gastropods, oligochaetes, polychaetes, turbellarians, rotifers, and nematodes), while taking most other prey organisms in approximate proportion to availability. Juvenile lumpsuckers in floating seaweed fed mainly on prey organisms found on the seaweed but also consumed organisms from the plankton. Ontogenetic changes in the diet were related to size of prey. Lumpsuckers began to feed while they still had some yolk, primarily on small prey, including crustacean larvae and halacarid mites. After they completely absorbed their yolk, juveniles first fed largely on harpacticoids, but amphipods, isopods, and smaller juvenile lumpsuckers formed an increasing proportion of their diet as they grew. Behavioral selection of prey, rather than an increasing ability to ingest larger items, is suggested to be the basis for ontogenetic changes in diet.

Both color (i.e., reflectance) and body size should influence body temperature in heliothermic ectotherms. We compared heating rates and equilibrium temperatures between the normal striped morph and the solid black melanistic morph of the garter snake, Thamnophis sirtalis, from polymorphic populations in the Lake Erie region. Snakes ranging in mass from 2.6–216.2 g were divided into three size classes (small, medium, and large). Using temperature-sensitive PIT tags, we tested pairs of snakes under artificial light in an environmental chamber, then used curvilinear regressions to estimate heating rate and equilibrium temperature. In small and medium-sized snakes, we found no difference in heating rate nor equilibrium temperature between morphs, suggesting that melanism does not provide a thermal advantage in young snakes. In large snakes, morph affected equilibrium temperature, but not heating rate. Melanistics averaged 1.3 C warmer than striped snakes. This difference may represent a thermal advantage for adults, of which gravid females are the largest and may have the most to gain from a thermal advantage.

Undescribed bones located in pectoral region of Muraenidae are reported. Typically there are either one or two small horn-shaped bones located posterior to intersection of supracleithrum and cleithrum. A deep concavity is present at posterior end of each bone. In species with a single bone, posterior section of bone is attached to a triangular sheet of cartilage. In species with two bones, one is dorsal to the other, and no posterior sheet of cartilage is associated with either. Of the two subfamilies of Muraenidae, the bones are lacking in all but one species of Uropterygiinae and vary in presence and number in Muraeninae. Monopenchelys acuta lacks these bones but has a posterior sheet of cartilage. Gymnothorax melatremus has three bone elements. Comparisons with pectoral bones of other anguilliform taxa suggests that bones in muraenids represent the scapula and coracoid.

Mole salamanders, Ambystoma talpoideum, are one of several species that exhibit facultative paedomorphosis. Many characteristics of paedomorphs and metamorphs have been compared in an effort to understand the ecological and evolutionary significance of facultative paedomorphosis, but few physiological comparisons have been made. We measured resting metabolic rates (oxygen consumption) of paedomorphic and metamorphic mole salamanders, under aquatic (both morphs) and terrestrial (metamorphs) conditions in an effort to compare maintenance energy expenditures of these phenotypes. There were no statistically significant differences in metabolic rates between morphs during aquatic trials. Under aquatic conditions, size adjusted oxygen consumption rates ranged from a low of 0.085 ml/h to 0.194 ml/h. There was a trend for oxygen consumption to increase with temperature, and at night compared to day, but significant interactions among time of day, temperature, and phenotype revealed complex responses. Most interesting, although metamorphs and paedomorphs had indistinguishable metabolic rates in water, both morphs in water consumed 2–4 times as much oxygen as did metamorphs in air. Our results suggest that metamorphs, while in a terrestrial environment, may expend significantly less energy for maintenance than aquatic paedomorphs.

The suborder Clupeoidei, with about 350 species, includes almost all Recent species of the Clupeomorpha, but relationships among the three clupeoid superfamilies (Engrauloidea, Clupeoidea and Pristigasteroidea) remain unresolved to date. The Clupeoidea and Engrauloidea are herein hypothesized as sister groups on the basis of morphological evidence. Among the proposed characters, only the presence of cartilage chevrons at the tips of epicentrals was previously reported as a possible synapomorphy for the Clupeoidea Engrauloidea. Two additional characters are herein proposed in support of this hypothesis: the posteriorly directed parapophyses of the second vertebra and the interzygapophysal articulation. Evidence counter to this proposed relationship is the common presence of the gongyloid cartilage in the branchial arches of Pristigasteroidea and Engrauloidea, a structure apparently previously unrecorded in the literature and whose homologies are discussed. Additional circumstantial evidence for the clade Clupeoidea Engrauloidea are also discussed. The position of Pristigasteroidea as a basal group of Clupeoidei has potential implications for the currently accepted sister-group relationship between Clupeomorpha and Ostariophysi.

Many studies have suggested that incubating eggs under wet conditions may lead to increased fitness in snapping turtles immediately following emergence from the nest, but little is known of the consequences of associated elevated embryonic yolk use on the energetic reserves of the hatchlings during the first winter. In this experiment, we measured the size, dry mass, and triglyceride contents of the carcasses and yolk sacs of hatchlings from eggs incubated under wet (−50 kPa) and dry (−300 kPa) conditions at three time intervals: at one week posthatching (late August); at the onset of an overwintering period following 10 weeks of ad libitum feeding (early November); and at the end of overwintering (late March). Although initially smaller, dry hatchlings demonstrated greater increases in live mass during the autumn than did wet hatchlings, eliminating differences in live mass by early November. Dry carcass masses were greater in wet-treatment hatchlings at one week posthatching but not in either November or March. Dry yolk sac mass was greater in dry hatchlings only at one week posthatching. Total triglyceride contents were higher in dry hatchlings than in wet hatchlings at all intervals. These findings suggest that possible preliminary survival advantages of hatchlings emerging from wet nests ultimately may be tempered by decreased energy reserves during the first winter.

In aquatic communities, the phenology of breeding may influence species interactions. In the early-breeding marbled salamander, Ambystoma opacum, timing of pond filling may determine whether interactions among larvae are competitive or predatory. The objectives of our studies were to determine how time of egg hatching affected size, larval period, and survival to metamorphosis in A. opacum, and if early-hatching in A. opacum influenced the competitive and predator-prey relationships with smaller larvae of the mole salamander, Ambystoma talpoideum. Salamander larvae were reared from hatching through metamorphosis in large, outdoor enclosures located in a natural temporary pond in Aiken County, South Carolina, in two experiments. In study 1, we reared early- and late-hatching A. opacum larvae separately from hatching through metamorphosis. In study 2, we examined how early- versus late-hatching A. opacum affected a syntopic species, A. talpoideum. In general, early-hatching A. opacum were larger and older at metamorphosis, had greater survival, and left the pond earlier than late-hatching larvae. Ambystoma talpoideum reared in the presence of early-hatching A. opacum had lower survival than in controls, suggesting that A. opacum may predate upon A. talpoideum when they gain a growth advantage over later-hatching larvae. Our studies demonstrate that time of pond filling and phenology of breeding may influence population dynamics and alter the nature of relationships that develop among species.