Shiners of the cyprinid genus Cyprinella are abundant and broadly distributed in eastern and central North America. Thirty species are currently placed in the genus: these include six species restricted to Mexico and three barbeled forms formerly placed in different cyprinid genera (primarily Hybopsis). We conducted a molecular phylogenetic analysis of all species of Cyprinella found in the United States, using complete nucleotide sequences of the mitochondrial, protein-coding genes ND2 and ND4L. Maximum-parsimony analysis recovered a single most-parsimonious tree for Cyprinella. Among historically recognized, nonbarbeled Cyprinella, the mitochondrial (mt) DNA tree indicated that basal lineages in Cyprinella are comprised largely of species with linear breeding tubercles and that are endemic to Atlantic and/or Gulf slope drainages, whereas derived lineages are comprised of species broadly distributed in the Mississippi basin and the American Southwest. The Alabama Shiner, C. callistia, was basal in the mtDNA tree, although a monophyletic Cyprinella that included C. callistia was not supported in more than 50% of bootstrap replicates. There was strong bootstrap support (89%) for a clade that included all species of nonbarbeled Cyprinella (except C. callistia) and two barbeled species, C. labrosa and C. zanema. The third barbeled species, C. monacha, fell outside of Cyprinella sister to a species of Hybopsis. Within Cyprinella were a series of well-supported species groups, although in some cases bootstrap support for relationships among groups was below 50%. A derived clade consisting of C. spiloptera, C. whipplei, C. venusta, and the southwestern C. lutrensis group was strongly supported. The species C. lutrensis and C. lepida were not monophyletic, suggesting further study and revision within this group are warranted. In general, the most-parsimonious mtDNA tree was similar in terms of relationships among species to those proposed more than 40 years ago by R. H. Gibbs.

Relative fitness of parental and hybrid Leopard Frogs was examined by measuring larval performance in artificial ponds and laboratory containers. Effect of a variable hydroperiod on growth, development, and survival was used to assess larval responses to a desiccating aquatic environment. Larvae for the artificial pond experiment were obtained from field-collected egg masses of Rana blairi and R. sphenocephala. Artificial crosses with adult animals produced larvae of one parental and three hybrid genotypes for laboratory performance assays. Experimental pond drying significantly reduced survival for both parental species. Rana blairi had higher survival than R. sphenocephala across all treatments. Both species reduced larval period lengths when exposed to a drying environment relative to constant water levels. The laboratory experiment revealed Backcross₂ hybrid larvae exhibited longer larval period lengths than parental R. sphenocephala and certain F₁ hybrid genotypes in the drying environment. Proportion of survivors metamorphosing was greatest for the F₁ hybrid genotype SB and lowest for the Backcross₂ hybrid genotype. Consequently, advanced-generation hybrid genotypes (i.e., Backcross₂) did not perform well in desiccating environments. Direct measurements of important fitness components of parental and hybrid genotypes are critical for determining the evolutionary potential of natural hybridization.

Crystallaria asprella, sole member of the genus Crystallaria, was distributed throughout much of the eastern United States but today persists only in isolated populations. We quantified genetic variation among remaining populations of C. asprella by sequencing the mitochondrially encoded cytochrome b (cyt b) gene in 24 individuals from five sample localities. Phylogenetic analysis of these samples and individuals from eight other darter species, Perca, Gymnocephalus, Stizostedion, and Zingel, resulted in 80 equally most-parsimonious trees. Four of the five populations of C. asprella were monophyletic in all trees. Monophyly of the population from the Cahaba River was supported in 60 of 80 most-parsimonious trees. In the remaining 20 trees, one individual from the Cahaba River was included in a trichotomy with a clade of the other individuals from the Cahaba River and a clade of individuals from the Pearl River. The overall pattern of relationships among populations of C. asprella was (Elk River, WV (Saline River, AR (Zumbro River, MN (Cahaba River, AL, Pearl River, LA)))). The most divergent population of C. asprella is from the Elk River in West Virginia. In spite of considerable collecting effort, only five individuals have been collected from the Elk River since 1987. Crystallaria asprella from the Elk River differ from other populations by 11.2–11.8% sequence divergence. Their continued existence is currently threatened by logging, coal mining, and natural gas exploration. Our data document a distinct evolutionarily significant unit in the Elk River that likely is in great peril and should be protected under the U.S. Endangered Species Act.

We examined the genetic population structure of Long-Toed Salamanders (Ambystoma macrodactylum) from the Bitterroot Mountains of Idaho and Montana to better understand their evolutionary history and genetic population structure. Populations show high levels of within-population genetic variation at six polymorphic allozyme loci (H̄_s = 0.09 for all 18 loci examined; range 0.04–0.14). There is very little divergence among populations within basins, suggesting panmixia within basins. In contrast, genetic differentiation among all populations is high (G_st = 0.30). We used computer simulations to examine population structures that could have led to the observed distribution of genetic variation, assuming selective neutrality of the allozymes. To test the assumption of selective neutrality of the markers used in this study, we compared the observed divergence among the allozymes to that expected from simulations of independently segregating and selectively neutral markers. The observed genetic divergence among populations is compatible with that expected for neutral genetic markers sampled from panmictic populations within basins that exchange less than one migrant among basins each generation.

Previous studies have shown that predation by large fishes (> 200 mm TL) is responsible for greater mortality rates of juvenile Acanthochromis polyacanthus on continuous than on patch reefs. Yet 43% of mortality on continuous reefs cannot be explained by these piscivores. I hypothesized that small predatory fishes are a source of this unaccounted mortality and tested the prediction that juvenile A. polyacanthus encounter small predatory fishes at a greater rate on continuous than on patch reefs. Of all fishes encountered by A. polyacanthus, fishes known to be potential predators of A. polyacanthus were most frequently encountered. There was a trend for A. polyacanthus to encounter these species at a greater rate on continuous than on patch reefs, but this was not supported by the analyses. This result highlights current uncertainty about sources of mortality in juvenile reef fishes. Future research is needed to establish the relative contribution of alternate sources of mortality to overall mortality so that the predictive power of hypotheses about processes that control reef fish abundance can be improved.

Sequences of two mitochondrial genes (385 base pairs of cytochrome b and approximately 520 base pairs of 16S DNA) were gathered for 26 taxa of the Middle American plethodontid salamander genera Nototriton and Oedipina and from three outgroup members of the tribe Bolitoglossini. Phylogenetic analyses of these data reveal well-supported cladistic structure and demonstrate the paraphyly of the moss salamanders of the genus Nototriton, which includes two well-defined clades. One clade, the sister taxon of Oedipina, corresponding to the Costa Rican and Honduran species of the picadoi, richardi, and barbouri groups, retains the name Nototriton. A new name is required for the second clade, the sister taxon of Oedipina plus Nototriton (sensu stricto). This clade, which we name Cryptotriton, is well supported morphologically and includes the species of the nasalis and adelos groups. A new species of Nototriton from Monteverde, Costa Rica, is described as Nototriton gamezi. Species of Oedipina fall into two clades that we treat as subgenera. Oedipina (sensu stricto) includes the longer-bodied, generally more slender and darker colored species and is the more speciose clade. Oedopinola includes the shorter-bodied, generally more robust and lighter-colored species. Two new species of the latter clade are described, Oedipina maritima from the lowlands of northwestern Panamá, and Oedipina savagei, from uplands of southwestern Costa Rica.

Several papers have suggested that the Freshwater Cichlid Crenicara punctulata is capable of protogynous sex change. These studies provide behavioral data and descriptive details of external morphology but lack information about gonadal histology, which is essential for definitive evidence of sequential hermaphroditism. Therefore, this study was designed to determine whether C. punctulata is a sequential hermaphrodite. The present study included a behavioral experiment, an isolation/transformation experiment, as well as a detailed analysis of gonadal structure. The behavioral experiment established social hierarchies in four groups of juvenile female C. punctulata. The hypothesis that the dominant female in each group would be the only individual to develop male secondary sexual characteristics in that group was verified. The isolation experiment tested the hypothesis that female C. punctulata would change sex without the presence of conspecifics. After social isolation, females that were previously dominant among a group of females in a male harem developed male secondary sexual characteristics. Histological analysis revealed that these individuals possessed testes, whereas all dominant females examined possessed mature ovaries. The results from behavioral, isolation, and histological portions of this project strongly suggest that C. punctulata is a protogynous sequential hermaphrodite, at least in captivity.

Two sphaerodactyline geckos, Gonatodes hasemani and G. humeralis were studied in eastern Rondônia, Brazil, to determine ecological factors allowing coexistence. Gonatodes hasemani lives primarily on fallen logs in undisturbed forest, whereas G. humeralis lives primarily on tree trunks. Although both species occur in most forest patches, G. hasemani is more common within terra firme (never flooded) forest, and G. humeralis is more common in forest adjacent to rivers. Gonatodes hasemani is slightly larger in body size and is more robust than the more arboreal G. humeralis. Both species are active at the same time during the day, maintain the same body temperatures, and are most frequently found in shade. Dietary overlaps based on numbers (0.831) and volumes (0.877) of prey types were high indicating relatively similar diets. Differences in prey types appear to reflect differences in microhabitat use, and both species eat prey of the same size. Reproductive characteristics are similar but the larger bodied G. hasemani produces slightly larger eggs. The niche axis on which these two lizards most clearly separate is microhabitat: G. hasemani uses lower perches with larger diameters in the forest primarily because individuals typically are found on fallen logs, whereas G. humeralis uses higher and thinner perches because individuals are typically found on tree trunks and vines. Limited data on snakes that prey on small lizards in Amazon forest suggests the possibility that niche differences between these Gonatodes species may be mediated by predators.

Dois lagartos geconídeos Sphaerodactylinae, Gonatodes hasemani e G. humeralis, foram estudados no leste de Rondônia, Brasil, com o intuito de se determinar os fatores ecológicos que permitem sua coexistência. Gonatodes hasemani vive primariamente sobre troncos de árvores caídos, em mata não perturbada, enquanto G. humeralis vive primariamente sobre troncos em pé. Embora ambas as espécies ocorram na maioria das áreas de mata, G. hasemani é mais comum em mata de terra firme, enquanto G. humeralis é mais comum em matas adjacentes a rios. Gonatodes hasemani é ligeiramente maior quanto ao tamanho do corpo e mais robusto que seu congênere mais arborícola, G. humeralis. Ambas as espécies estão ativas nas mesmas horas do dia, mantêm a mesma temperatura corporal, e são mais frequentemente encontradas na sombra. Uma grande sobreposição na dieta, tanto baseada em número (0.831) quanto em volume (0.877) de tipos de presas indica dietas relativamente similares. As diferenças observadas nos tipos de presas parecem refletir diferenças no uso de microhabitats, sendo o tamanho das presas semelhantes para as duas espécies. As características reprodutivas são semelhantes, mas G. hasemani, que possui um corpo maior, produz ovos ligeiramente maiores. O eixo no qual esses dois lagartos mais claramente se separam, no que diz respeito ao nicho, é o microhabitat: G. hasemani utiliza substratos mais baixos e de maior diâmetro na mata, primariamente porque indivíduos são tipicamente encontrados em troncos caídos, ao passo que G. humeralis utiliza substratos mais altos e mais finos, já que indivíduos são encontrados tipicamente sobre troncos de árvores vivas e cipós. Os dados, ainda que limitados, sobre cobras que se alimentam de pequenos lagartos na floresta amazônica sugerem a possibilidade de que as diferenças de nicho entre essas duas espécies de Gonatodes possam ser mediadas por predadores.

Fourteen species of Eustomias with two pectoral fin rays and short, branched barbels have been described from the North Atlantic, most of them based on single specimens. All but six of these nomimal species have at one time or another been placed in the synonymy of one of the others. Examination of many more specimens indicates that 11 of the 14 are valid species. Two of these have been reviewed previously. Of the nine considered here, Eustomias bigelowi, E. fissibarbis, E. macronema, E. satterleei, and E. schmidti are each represented by numerous specimens from throughout much of the Atlantic and Indo-Pacific. Eustomias binghami, E. paucifilis, E. silvescens, and E. triramis, some still represented by only one or a few specimens, are apparently confined to restricted areas of the North Atlantic. Two new species are described: E. borealis from the North Atlantic and E. curtifilis from the South Atlantic.

Foraging methods of insectivorous lizards fall into two major modes, ambush foraging, in which the lizard waits immobile to detect prey, and active foraging, in which the lizard moves through its habitat while searching for prey. Both modes exhibit remarkable phylogenetic stability. Ambush foraging is the sole mode of all iguanians examined to date, and active foraging is the only known mode in large scleroglossan clades such as Teiidae and Varanoidea. We present quantitative data on foraging behavior demonstrating the existence of intrageneric variation in foraging mode in the scincid genus Mabuya in southern Africa. Like the large majority of skinks, Mabuya striata sparsa, M. sulcata, and M. variegata are active foragers that have high values of number of movements per minute (MPM), proportion of time spent moving (PTM), and mean speed (average speed including time spent immobile) but relatively low speed while moving. In contrast, M. acutilabris and M. spilogaster are ambush foragers having significantly lower MPM, PTM, and mean speed but higher average speed while moving than the other species. The importance of these findings is twofold. First, intrafamilial variation in foraging mode in Scincidae and intrageneric variation are verified for Mabuya. Second, because intrageneric variation in foraging mode was previously known from quantitative data only in the lacertid genera Acanthodactylus and Pedioplanis (and atypically in Meroles), an excellent opportunity is provided to test hypotheses about foraging mode without confounding interfamilial phylogenetic differences.

Nest site selection in reptiles can affect the fitness of the parents through the survival of their offspring because environmental factors influence embryo survivorship, hatchling quality, and sex ratio. In sea turtles, nest site selection is influenced by selective forces that drive nest placement inland and those that drive nest placement seaward. Nests deposited close to the ocean have a greater likelihood of inundation and egg loss to erosion whereas nest placement farther inland results in greater likelihood of desiccation, hatchling misorientation, and predation on nesting females, eggs, and hatchlings. To evaluate the role of microhabitat cues in nest site selection in Loggerhead Sea Turtles (Caretta caretta), we assessed temperature, moisture, salinity (conductivity), and slope along the tracks of 45 female loggerheads during their beach ascent from the ocean to nest sites in the Archie Carr National Wildlife Refuge in Florida on the beach with the greatest density of loggerhead nesting in the Atlantic. Of the four environmental factors evaluated (slope, temperature, moisture, and salinity), slope appears to have the greatest influence on nest site selection, perhaps because it is associated with nest elevation. Our results refute the current hypothesis that an abrupt increase in temperature is used by loggerheads as a cue for excavating a nest. Moisture content and salinity of surface sand are potential cues but may not be reliable for nest site selection because they can vary substantially and rapidly in response to rainfall and changes in the water table. Sea turtles may use multiple cues for nest site selection either in series with a threshold that must be reached for each environmental factor before the turtle initiates nest excavation or integrated as specific patterns of associations.

A new species, Hapalogenys merguiensis, currently known only from Andaman Sea, is described from the holotype and five paratypes. This species is most similar to H. nitens Richardson, 1845, in overall appearance of body, as well as in having a single notched dorsal fin, poorly developed papillae on chin and dark brownish body color with two oblique dark bands curved posteriorly. However, it differs from H. nitens, from which it is also geographically separated, in a combination of several meristic and morphometric characters. Hapalogenys merguiensis n. sp. has the following diagnostic characters: dorsal fin rays XI, 14; anal fin rays III, 9 or 10; pored lateral line scales 39–42; gillrakers 5–7 12–14; scales above lateral line 9 or 10, below 18–20; no scales on maxilla; eye diameter more than approximately one-quarter head length; 10 pores on and behind chin; a cluster of very short dense papillae on fleshy lower lip; head and body generally dark brownish and two indistinct oblique bands on body, first descending from nape to behind pectoral fin and second from base of anterior second or third dorsal fin spines and soft dorsal fin base, curving posteriorly through lateral line to soft anal fin and caudal peduncle (one whitish or indistinct whitish brown, oblique band, curving posteriorly and becoming wider, from base of the first three dorsal fin spines to anus and spinous anal fin base); dark posterior margin absent from soft dorsal and anal fins but narrowly present on caudal fin; a procumbent spinelike process (exposed tip of first pterygiophore) at origin of dorsal fin.

Unlike many polygynous species, we found that females of the lizard, Anolis carolinensis, have the same repertoire of aggressive signals as males. These shared signals included three stereotyped headbob display patterns (types A, B, and C) that were performed with no significant intersexual difference in amplitude displacement. However, we did find the following sexual dimorphisms in signal structure and use. Females (1) had a smaller average extendable throat fan (i.e., dewlap) area (0.22 cm²) than males (1.52 cm²), (2) never displayed when alone (0/h), whereas males frequently did (18/h), (3) displayed 10-fold less during consexual encounters (17/h) than males (168/h), (4) lacked the ritualized intermale combat scheme of circling, jaw-sparring, and jaw-locking, (5) infrequently used physical contact in consexual encounters, whereas males frequently did, and (6) did not employ a shifting use of signals with decreasing interfemale approach distance, whereas contesting males did by decreasing the frequency of C displays in favor of A and B displays, decreasing the use of the dewlap during displays, and decreasing the sequencing of displays in volleys. These results are in accord with field studies, which report limited interfemale territoriality (i.e., low consexual threat) and short display broadcast distances, whereas male territorial behavior is well developed (i.e., high consexual threat), with frequent long-distance displaying between consexuals. We suggest that these displays, which function in competitive interference, have been less directionally selected in females than in males because the outcomes of consexual contests carry fewer reproductive consequences for females than for males.

Characidium vestigipinne, a new species of fish of the crenuchid subfamily Characidiinae is described from the upper rio Uruguay drainage, state of Rio Grande do Sul, Brazil. The species belongs to a monophyletic assemblage that also includes C. occidentale, C. orientale, and C. rachovii. The group is diagnosed by the presence of roundish black marks on the pelvic, dorsal, and anal fins, and three other characters related to sexual dimorphism. Within this group the absence or reduction of the adipose fin uniquely diagnoses Characidium vestigipinne. An updated identification key is presented for the seven species of Characidium occurring in southern Brazil.

Descreve-se Characidium vestigipinne, nova espécie de peixe crenuquídeo da subfamília Characidiinae da bacia do alto rio Uruguai, Estado do Rio Grande do Sul, Brasil. A nova espécie pertence a um grupo monofilético que também inclui C. occidentale, C. orientale e C. rachovii. Este grupo é diagnosticado pela presença de manchas pretas arredondadas nas nadadeiras pélvicas, dorsal e anal, e por três outras sinapomorfias associadas a dimorfismo sexual. Dentro deste grupo C. vestigipinne é diagnosticado pela ausência ou tamanho reduzido da nadeira adiposa. Apresenta-se uma chave atualizada de identificação das espécies de Characidium ocorrentes no sul do Brasil.

I examined how the distributions of the plethodontid salamanders Desmognathus monticola, D. fuscus, Eurycea cirrigera, Plethodon cinereus, and P. glutinosus were related to interspecific differences in the characteristics of their retreats and differences in their dehydration and rehydration rates. There was little spatial overlap between the terrestrial species, Plethodon cinereus and P. glutinosus, and the largest two semiaquatic species, Desmognathus monticola and D. fuscus. Terrestrial species occupied retreats that were considerably drier than those of semiaquatic species, but they selected larger cover objects. Body size appeared to influence microhabitat use as well. Among both the terrestrial and the semiaquatic salamanders, large species used wider cover objects, deeper retreats, and occupied cooler retreat sites than smaller species. Among the semiaquatic salamanders, larger species were found closer to water than smaller species. Rehydration rates paralleled habitat use. Species found farther from water on searches of transects rehydrated faster than species inhabiting wetter habitats closer to water. Salamanders were found significantly farther from water on transects where the large aquatic salamander Desmognathus quadramaculatus was present than on transects where it was absent. The findings of this study are consistent with the hypothesis that species distributions along environmental gradients are frequently determined by opposing gradients in the influence of limiting environmental factors and the influence of dominant competitors and predators.

Both adult males and females of the Red-Backed Salamander (Plethodon cinereus) maintain feeding territories under cover objects (rocks and logs on the forest floor) during the summer noncourtship and autumn and spring courtship seasons. Previous research found that, during the summer, 28% of the adults occurred as male-female pairs under cover objects, whereas male-male and female-female pairs rarely occurred. Therefore, we tested the hypothesis that male-female pairs codefend territories against intruders during the courtship season and that such codefense extends into the noncourtship summer. During October 1996 and June 1997, we collected male-female pairs, single males, and single females at Mountain Lake Biological Station, Virginia. In laboratory experiments, we employed six randomized treatments during the courtship season (n = 27 pairs) but only the first two treatments during the noncourtship season (n = 29 pairs). The treatments were the male-female pair confronting (1) a single male intruder and (2) a single female intruder, the male resident alone confronting (3) a single male intruder and (4) a single female intruder, and the female resident alone confronting (5) a single male intruder and (6) a single female intruder. During the courtship season, intruding males did not spend significantly different amounts of time on territories defended by a male-female pair versus territories defended by a single salamander (male or female) from the pair. However, during the courtship season intruding females did spend significantly less time on territories defended by a male-female pair versus territories defended by a single salamander (male or female) from the pair. Male and female intruders spent significantly less time on territories defended by a pair during the courtship season compared to the noncourtship season. During both the courtship and noncourtship seasons, males in pairs spent significantly more time in aggression toward intruding males than did their female partners, and females in pairs spent significantly more time in aggression toward intruding females than did their partners. Thus, our experiment suggests that male-female pairs as residents can codefend territories but not in a cooperative manner. Because paired male residents were more aggressive to male intruders, whereas paired female residents were more aggressive to female intruders, we suggest that males in pairs may not be willing to pass up future polygynous relationships, and females in pairs may not be willing to pass up future polyandrous relationships.

We investigated morphological plasticity to the presence of predators in the tadpoles of four ranid frog species distributed along a pond hydroperiod gradient in southeast Michigan. We first reared all four species (Wood Frog, Rana sylvatica; Leopard Frog R. pipiens; Green Frog, R. clamitans; and Bullfrog, R. catesbeiana) under identical laboratory conditions in the presence and absence of caged larval dragonflies (Anax spp.). We then reared wood frog and leopard frog in outdoor mesocosms to examine the predator-induced responses during ontogeny. Finally, we reared leopard frog with predators fed either leopard frog or wood frog larvae to determine whether prey responses depended upon predators consuming conspecific prey. All four ranids exhibited some degree of morphological change in the presence of Anax; these differences were species specific and fairly robust to different experimental conditions. The responses over ontogeny indicated that the changes were direct responses to the predator's presence and not an indirect result of the predator slowing anuran growth or development. Finally, larval leopard frog responded similarly to predators feeding on conspecifics and congenerics. Taken together, these results suggest that morphological responses to predators may be relatively common in larval anurans. Further, because many of the responses are known to be adaptive antipredator strategies, predator-induced morphological plasticity has important evolutionary and ecological implications.

We describe a new species of Luperosaurus from first growth, low-elevation, closed canopy rain forest on Mt. Tompotika at the tip of the eastern peninsula of the island of Sulawesi (Celebes), Indonesia. The new species is the first record of the genus Luperosaurus from this island and differs from all known species of Luperosaurus by numerous morphological characters and a unique color pattern. The new species also shares some presumably derived character states with members of the genus Ptychozoon. A phylogenetic analysis of 24 morphological characters is consistent with the previously hypothesized presence of two species groups (putative lineages) within the genus Luperosaurus. The analysis suggests that the new species from Sulawesi may either belong to a clade also including L. brooksi and L. browni or may fall basal to the remaining Luperosaurus. The monophyly of the species currently referred to Luperosaurus is questionable. We consider Luperosaurus serraticaudus a junior synonym of L. browni.

The effects on feeding of single and aggregated Bufo crucifer tadpoles were tested for 24 h in experimental pens in the field. Single tadpoles ate significantly lower amounts of cyanophytes (Cyanophyta) and heterotrophs than grouped tadpoles. Diatoms (Chrysophyta) and other algae (Chlorophyta, Euglenophyta and Pyrrophyta) were eaten in similar amounts by individuals from both treatments. In general, diets of aggregated and single tadpoles were similar in both diversity of taxa and proportions of different taxa. However, the reduction of cyanophytes and heterotrophs in the diet of isolated tadpoles might lead to some disadvantage through development if these food items are important to the required nutrient balance of B. crucifer.

Experimental populations of the cannibalistic livebearer, Gambusia affinis, were exposed to varying degrees of shelter for juveniles vulnerable to cannibalism by adults. High densities of shelter significantly reduced the effects of cannibalism and effectively maintained reproducing populations throughout the experiment (380 days). Population densities continuously declined in medium and low refuge density treatments due to a lack of recruitment. The size distributions of fish in these treatments narrowed with time, although the rate at which this occurred was greater in the low refuge density treatment.

Two species of horned lizards, Phrynosoma braconnieri and P. taurus, are endemic to México and inhabit medium and high-elevation sites in the states of Oaxaca, Guerrero, and Puebla. We compiled information on distribution and reproductive cycle for these two species from the literature and from an examination of specimens in systematic collections. Our study confirms a viviparous mode of reproduction for both species and suggests that their reproductive cycles may be different from that observed in other viviparous Phrynosoma. Specifically, embryonic development occurs during the late fall and winter months, with a parturition date in early spring. In contrast, other viviparous horned lizards gestate during the spring and summer months and give birth to their young in the late summer. Examining the phylogenetic distribution of reproductive modes in this genus suggests that two high–elevation clades of horned lizards have independently evolved viviparity from an oviparous ancestor, yet each of these clades has evolved a distinct reproductive cycle.

Las especies endémicas de México Phrynosoma braconnieri y P. taurus habitan elevaciones intermedias y altas en los estados de Oaxaca, Guerrero y Puebla. En este trabajo revisamos ejemplares de colecciones y recopilamos información bibliográfica sobre la distribución y ciclos reproductivos de estas dos especies. Este estudio confirma la existencia de un modo de reproducción vivíparo en ambas especies, y sugiere que su ciclo reproductivo difiere del observado en otras especies vivíparas de Phrynosoma. En particular, en P. braconnieri y P. taurus el desarrollo embrionario se lleva a cabo durante el final del otoño y principios de invierno dándose el parto al principio de la primavera. En contraste, en otras especies vivíparas de Phrynosoma la gestación se realiza durante la primavera y el verano mientras que el parto ocurre en el verano tardío. La revisión de la distribución filogenética de los modos reproductivos en éste género, sugiere que dos clados de Phrynosoma que viven en elevaciones altas han adquirido independientemente un modo vivíparo a partir de un ancestro ovíparo. Sin embargo, cada uno de estos clados ha evolucionado un ciclo reproductivo particular.

We found significant variation among years in the reproductive life-history traits of a single population of the Banded Darter, Etheostoma zonale from the Duck River drainage of Tennessee. Standard length-adjusted average clutch size varied by a factor of 1.38 among years and adjusted ripe egg mass by a factor of 1.21. Interannual variation in E. zonale's clutch size appears to be less extensive than is geographic variation reported previously, and egg size is generally less variable than is clutch size, both geographically and temporally, as has been predicted from life-history theory.

Three restriction site markers from the mitochondrial genome are described for the toads Bufo microscaphus and B. woodhousii. Markers were resolved from DNA sequence data representing segments of cytochrome b (cytb) and 16S ribosomal genes. Two diagnostic restriction sites (BsmA I; SfaN I) characterize B. microscaphus for cytb, whereas a third restriction site (Tsp509 I) distinguishes B. woodhousii for 16S. Restriction digests of PCR-amplified cytb and 16S segments provide an economical, nondestructive assay with which to identify mtDNA haplotypes for these toads and their hybrids. The mtDNA markers complement diagnostic allozyme and call characters, offering an additional approach to examine hybridization between the two species in central Arizona.

To estimate residency and population sizes, endemic fishes were marked and released during October 1998 at confluence of Colorado River and Havasu Creek (Grand Canyon National Park, Coconino County, Arizona). Ripe Catostomus (Pantosteus) discobolus females and newly hatched fry confirmed late season (i.e., early October) spawning by this species. Reproduction by other catostomids was inferred through physical examination of adult C. latipinnis and by capture of a possible Xyrauchen texanus larva. The latter is an endangered species not considered a constituent member of the endemic Grand Canyon fish community; its potential presence in Grand Canyon will influence adaptive management of endemic and introduced fishes. Results of ANCOVAs (with fishing effort as covariate) indicated numbers of aggregating C. latipinnis were significantly associated with flows in Havasu Creek but not those in the mainstem Colorado River. The ecology of big-river endemic fishes in Grand Canyon is clearly linked to tributary outflows, and environmental cues which elicit spawning of native fishes are discussed.

The opportunity and ability to photobiosynthesize vitamin D₃ by exposing skin to ultraviolet-B (UVB) irradiation from the sun was compared using the nocturnal/crepuscular Mediterranean House Gecko Hemidactylus turcicus and the diurnal Texas Spiny Lizard Sceloporus olivaceous. Texas spiny lizards had a greater opportunity for photobiosynthetic production of vitamin D₃ than geckos. This was revealed by vitamin D₃ photoproduct production in models (ampoules containing an alcohol solution of vitamin D₃ precursor) placed at locations inhabited by free-living lizards at similar times of occupancy. Alternatively, geckos seemed able to maximize their limited photobiosynthetic opportunity with a higher rate of conversion of provitamin D₃ to photoproducts. This was revealed by photoproduct conversion in patches of lizard skin exposed to ultraviolet lamps in the laboratory. Stomach-content analysis showed the spiny lizards to have dietary sources of vitamin D₃, the geckos may or may not. This is the first documentation that mostly nocturnal geckos may rely on photobiosynthesis of vitamin D₃ and that they might have a more sensitive mechanism than diurnal lizards to compensate for their limited exposure to natural UVB radiation. Future studies should investigate sexual, seasonal, age, and species differences in photobiosynthetic opportunity and ability.

Chubs of the Gila River basin have been variously classified as nominal species, subspecies of Gila robusta, or a “complex.” Three full species, robusta, intermedia, and nigra are here recognized, the last possibly arising through more than one hybrization event between robusta and intermedia. Following resolution of a nomenclatural problem, G. nigra is characterized in a key for species identification. Listing under the Endangered Species Act is suggested for all species of Gila in the Colorado River basin.

We investigated phonotactic responses of amplexed and unamplexed females to different male calls in the Cricket Frog Acris crepitans blanchardi. A significantly higher proportion of amplexed females responded to male calls than did unamplexed females. When unamplexed females responded to male calls their phonotactic preferences did not differ from that of amplexed females. Amplexed and unamplexed females did not differ in their latency to respond to different male calls. Thus, the use of unamplexed females in phonotaxis experiments does not seem to bias any interpretation of preferences and would increase the number of testable females available.

Male Pygmy Sculpins (Cottus pygmaeus) were found to abandon nests that contained clutches of eggs, presumably establishing new nests elsewhere. These abandoned nests were readily occupied by new males (allopaternal males) that continued paternal care of existing clutches and usually acquired new clutches. Significantly more eggs were lost to cannibalism when new males acquired nests than when the original males stayed with their own brood. The size of males that abandoned nests did not differ from that of allopaternal males. Female preference for males with nests that already contain eggs may be the selective force for the occurrence of allopaternal care in this species.

This report documents the application of high field magnetic resonance imaging to viewing the central nervous system of garter snakes (12–43 g) with emphasis on the vomeronasal and olfactory systems. Slices in all three planes were taken in lightly sedated snakes showing many major neural structures with resolution down to less than 60 µm. The images were obtained as 8 or 16 serial slices with slice spacings of 0.25 mm and 0.25 mm thick and were processed to a 256 × 256 matrix with a field of view (FOV) of 14 or 25 mm. The vomeronasal organs, main and accessory olfactory bulbs, telencephalon, cortex, tectum, medulla, cerebellum, spinal cord, and other major features of the brain are clearly defined in the images. The value of noninvasive neural imaging in comparative and experimental studies of squamate reptiles will become increasingly recognized as the technology is further developed but can be effectively employed at present.

Ontogenetic changes in body shape and its associated allometry were studied in the Blacktail Shiner, Cyprinella venusta, using geometric morphometric methods. We used a single, large sample (n = 397; 182 males, 215 females), collected in Catahoula Creek, Jourdan River drainage, Hancock County, Mississippi. Ten body landmarks were digitized from each specimen, which yielded partial warp scores that were used as shape variables to describe body shape change during ontogeny, assess sexual dimorphism, and investigate the relationship between reproductive status and ontogenetic body shape change. We also assessed the effect of sexual dimorphism on size and body shape. The null hypothesis of isometry during ontogeny was strongly rejected by multivariate regression of shape on size for both sexes (males, P < 0.0001, F = 21.970; females, P < 0.0001, F = 16.238). We found large, highly significant sexually dimorphic differences in the body shapes of males and females (MANOVA for overall shape, P < 0.0001, F = 7.535, Wilks' lambda, 0.758), which remained significant using MANCOVA with size as a covariate (log SL, P < 0.0001, F = 34.872, Wilks' lambda, 0.438; log CS, P < 0.0001, F = 34.829, Wilks' lambda, 0.439). Moreover, the ontogeny of body shape differs between males and females. There were highly significant shape differences among reproductive classes within males and females. These findings suggest that change in reproductive status may occur in concert with body shape change.

Male and female Red-Backed Salamanders (Plethodon cinereus) establish territories under cover objects (rocks, logs) on forest floors of northeastern North America. Because females should be food limited and males mate limited in terms of fitness, we tested the hypothesis that territorial residents and invaders should differ intersexually in certain morphological or behavioral traits. We displaced males and females from cover objects on the forest floor at Mountain Lake Biological Station, Virginia, and monitored homing by displaced individuals and invasion of vacated cover objects by novel individuals. Neither residents nor invaders differed significantly intersexually in snout–vent lengths, total lengths, or sizes of cover objects inhabited. Also, the number of male versus female residents that successfully returned to their cover objects did not differ significantly. However, significantly more females than males invaded vacated cover objects, and they did so significantly faster. These data suggest that males and females play different strategies related to territorial acquisitions, which may reflect their different requirements for maximizing individual fitness.

Agonistic displays in the Blacktip Shark (Carcharhinus limbatus) were triggered by divers slowly ascending to the surface. Two locomotor elements, rolling and tilting, were identified. They closely resemble the behavior patterns of sharks trying to shake off Sharksuckers (Echeneis naucrates). Agonistic displays and the shaking off of sharksuckers could each derive directly from the the feeding act. Alternatively the similarity of the agonistic displays and the shaking off of sharksuckers offers the possibility as well that only one of the two is directly derived from the feeding act and the other subsequently derived from the first.

The designation of a neotype for Conopsis nasus is necessary because the type specimen is apparently lost, the original description is ambiguous and can be applied to more than one valid taxon, and there are inconsistencies with the previous designation of type locality. The neotype is chosen from the herpetological collections at the British Museum of Natural History and shows the typical characters as defined in the original description as well as the diagnostic characters for the species defined in a recent study.

Paddlefish rostra vary in size and shape suggesting existence of multiple morphotypes. Measurements for 118 adult paddlefish from a Mississippi delta river indicate that the rostrum becomes shorter, narrower, and straighter as a fish grows. Negative allometric growth of rostra, and high variation within size classes, may obscure existence of distinctive rostral morphotypes.

During the first year of life of Striped Bass Morone saxatilis, the effect of estuarine habitat use on growth rate is poorly understood. In a split-plot experiment, growth and feeding rates were compared between anadromous (Chesapeake Bay) and nonanadromous (Santee-Cooper) broods of juvenile striped bass (45–90 days posthatch) exposed to a range of salinity levels (0.5, 7, and 15 ppt) and temperatures (20, 24, and 28 C). At 28 C, which best simulated the summertime conditions of young juveniles, Chesapeake Bay fish showed highest growth performance. For this temperature and strain, growth was approximately 40% higher at 7 ppt than at 0.5 or 15 ppt. Santee-Cooper juveniles showed no response to salinity. Over combined temperature and salinity levels, Chesapeake Bay juveniles experienced 22% higher growth rates than did Santee-Cooper juveniles, supporting a proposal that early growth rates are inversely related to latitude. Because salinity had a strong effect on Chesapeake Bay striped bass growth rate, we also conclude that variation in distribution patterns within and among estuaries can substantially modify the expected latitudinal gradient in growth rate.

Sharks are seldom recorded as associates of reef-based cleaner fishes. Here we report on juvenile Caribbean Reef Sharks, Carcharhinus perezi, associated with Yellownose Gobies, Elacatinus randalli, off northern Brazil. The sharks sought out cleaning stations tended by the gobies and posed on the bottom while being cleaned. The bottom-resting habit of C. perezi possibly facilitates cleaning interactions with the bottom-dwelling cleaner gobies.

A solution of 75% ethyl alcohol (ETOH) and alizarin red S can be substituted for KOH-alizarin red S to stain bone. ETOH-alizarin, unlike KOH-alizarin, does not damage muscle or cartilage. ETOH-alizarin and acidified alcian blue (a cartilage stain) can be used in any order and as often as required to stain bone and cartilage in a single preparation that has not been exposed to KOH-alizarin or trypsin, remembering that the acidic effects of the alcian blue solution should be neutralized to prevent decalcification of weakly ossified elements.

A replacement name, Cottus paulus, is proposed for the Pygmy Sculpin, Cottus pygmaeus. The name Cottus pygmaeus was preoccupied by Cottus quadricornis pygmaeus Lönnberg (1932).