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Females of the Strawberry Poison Frog (Oophaga pumilio) are known to be aggressive toward other females. However, the function of this behavior in females has not been identified. We hypothesized that females are territorial, occupying and defending specific areas in defense of food resources. To test this hypothesis, we calculated the position and size of core areas and home ranges for each female in the study area and the frequency of aggressive and feeding behavior exhibited by females in these areas. We provide evidence, for the first time, that females are territorial; they defend their core area against other intruding females. To determine the potential resource defended by females, we examined aggressive behavior associated with defense of mates, oviposition, and tadpole-rearing sites. We found no evidence that females defended areas with males, or that oviposition and tadpole-rearing sites were limited and defended by females. Instead, our observations suggest that female territoriality is most likely associated with the defense of feeding areas.
The evolution of hermaphroditism in fishes has intrigued scientists for over a century, but few have studied fine-scale evolutionary transitions between sexual patterns within the context of detailed hypotheses regarding phylogenetic relationships. Our phylogenetic reconstruction of sexual patterns in the seabasses (Teleostei: Serranidae) using a composite tree of 47 species is consistent with the hypothesis that protogyny is the ancestral condition in the family from which other sexual patterns evolved. Under this scenario, members of the Anthiinae retained protogynous hermaphroditism, as did the serranine genera Centropristis and Cheilidoperca. Gonochorism evolved once in the genus Paralabrax, and simultaneous hermaphroditism evolved once in the lineage that includes species of Hypoplectrus, Serranus, Serraniculus, and Diplectrum. Androdioecy evolved once within the genus Serranus and was derived from simultaneous hermaphroditism. Results from this study differ from previous hypotheses on the evolution of sexual patterns in seabasses and suggest that sexual patterns in fishes can evolve in several directions within single lineages and do not require functional intermediates.
Call surveys used to monitor breeding choruses of anuran amphibians generate index values that are frequently used to represent the number of male frogs present, but few studies have quantified this relationship. We compared abundance of male Boreal Chorus Frogs (Pseudacris maculata), estimated using capture–recapture methods in two populations in Colorado, to call index values derived from automated recordings. Single index values, such as might result from large monitoring efforts, were unrelated to population size. A synthetic call saturation index (CSI), the daily proportion of the maximum possible sum of index values derived from multiple recordings, was greater in larger populations, but the relationship was not highly predictive.
Poeciliids provide a model system for comparative studies of life-history variation because of the relatively large number of species and the diversity of environments they occupy. Brachyrhaphis parismina is a narrow-bodied poeciliid that occupies rivers and streams in the eastern lowlands of Costa Rica. Detailed life-history information on species in the narrow-bodied clade of the genus Brachyrhaphis is lacking compared to the many studies on the round-bodied species of the genus. We test for variation in life history among five populations of Brachyrhaphis parismina, and for patterns of allometry associated with the reproductive value hypothesis among individuals. Life-history traits exhibited little variation among populations in contrast to variation observed among populations of round-bodied congeners. Furthermore, within locations females exhibit isometric patterns of reproductive allocation with female body size, thus life history varies little over a female's lifetime. This pattern is inconsistent with that expected from the reproductive value hypothesis. Variation among and within populations in this species may be constrained by the high flow environment they occupy.
A new species of lanternshark, Etmopterus sculptus (Squaliformes: Etmopteridae), is described from southern Africa. The new species closely resembles other members of the “Etmopterus lucifer” group, especially the western North Pacific E. brachyurus, in having linear rows of dermal denticles. The new species is fairly common along the upper continental slopes between Namibia and southern Mozambique at depths between 450 and 900 m. The new species can be distinguished from other members of the E. lucifer species complex by a combination of characteristics, including arrangement of flank and caudal markings, and shape, size, and arrangement of dermal denticles along the body.
The family Caristiidae, commonly known as manefishes or veilfins, includes seven species of mesopelagic, oceanic fishes found throughout the major ocean basins of the world. We present a partial revision of the family, including all of the “small mouth” species, which are distinguished from other species of the family by having an upper jaw that extends approximately to midorbit and is almost completely covered by the thin bones of the suborbital series, a broad suborbital space, and by the lack of palatine teeth. This group, previously thought to include only the genus Paracaristius, is described in full, including the establishment of a new genus and three new species. The new genus Neocaristius includes only Neocaristius heemstrai, a distinctive species that is distinguished from all other species in this group by dentition, lateral-line morphology, dorsal-fin origin, and orbit size, as well as other meristic and morphometric characters. Neocaristius heemstrai is a circumaustral species, known from the South Atlantic, South Pacific, and southern Indian Ocean. The genus Paracaristius includes four species, P. maderensis and three species newly described herein. Species of Paracaristius are distinguished from each other on the basis of meristics, dentition, presence or absence of papillae on the hyoid arch, and placement of the dorsal fin. Two species of Paracaristius, P. nemorosus, new species, and P. aquilus, new species, are apparently resticted to the eastern tropical Atlantic, while the other two, P. nudarcus, new species, and P. maderensis are more widespread.
Gymnorhamphichthys britskii, new species, is described from the Paraná–Paraguay system. The new species is distinguished from all other congeners except G. hypostomus in having 5–16 (usually 9–13) large dark saddle-shaped pigment bars over the dorsal midline, extending between the nape and a vertical with the end of the anal fin, and sometimes reaching to or slightly below the lateral line. The new species differs from G. hypostomus in having 141–172 vs. 178–211 anal-fin rays; a shorter snout, preorbital distance 48.1–60.3% of head length (mean 54.6%) vs. 58.3–68.6% (mean 63.9%); a larger eye, diameter 5.7–9.0% of head length (mean 7.0%) vs. 3.3–5.9% (mean 4.3%); a longer distance from tip of snout to posterior nares, 17.1–22.0% of head length (mean 19.2%) vs. 11.2–17.1% (mean 13.8%); 7 vs. 9–13 displaced hemal spines; and 64–69 vs. 71–75 vertebrae to end of anal fin.
Gymnorhamphichthys britskii, nova espécie, é descrita para o sistema Paraná–Paraguai. A nova espécie se diferencia das demais de Gymnorhamphichthys, exceto G. hypostomus pela presença de 5–16 (usualmente 9–13) manchas negras dorsais alcançando ou ultrapassando a linha lateral, entre a nuca e a vertical do final da nadadeira anal. A nova espécie se diferencia de G. hypostomus pela presença de 141–172 raios na nadadeira anal vs. 178–211; por um menor focinho, comprimento preorbital 48.1–60.3% do comprimento da cabeça (média 54.6%) vs. 58.3–68.6% (média 63.9%); por um maior diâmetro do olho, 5.7–9.0% do comprimento da cabeça (média 7.0%) vs. 3.3–5.9% do comprimento da cabeça (média 4.3%); por uma maior distância do focinho até as narinas posteriores 17.1–22.0% (média 19.2%) vs. 11.2–17.1% do comprimento da cabeça (média 13.8%); pelo número de espinhos hemais deslocados, 7 vs. 9–13 e pelo número de vértebras até o final da nadadeira anal, 64–69 vs. 71–75 em G. hypostomus.
Cat-eyed snakes (Leptodeira) were thought to be closely related to nightsnakes (Hypsiglena and Pseudoleptodeira) based on morphology and immunological data, which allied these genera with blunt-headed vine snakes (Imantodes) and the Cloud Forest Snake (Cryophis hallbergi ). We collected sequence data from six protein-encoding nuclear loci (SLC30A1, ZEB2, FSHR, NTF3, DNAH3, and PNN; 4149 bp) and additional mtDNA data (nad5; 955 bp) added to published cob and nad4 (total 2387 bp mtDNA) from these and other rear-fanged, mildly venomous snakes that prey on vertebrates (frogs and lizards) and from several other dipsadine genera (Dipsas, Sibon, and Atractus) that prey on invertebrates (goo-eaters). We analyzed relationships using concatenation and a coalescent species-tree method. When analyzed separately, using either concatenation or coalescent methods, nuclear data support a different overall topology from the mtDNA data. Like the mtDNA data, the nuclear data support the Leptodeira Imantodes relationship, but instead place this clade more closely to the goo-eaters, with the nightsnakes as the basal divergence in the group. When the data are combined in concatenation analyses, the more variable mtDNA data appear to overwhelm the nuclear data, but not under the coalescent model.
A new species of Poecilia from the Atlantic slopes of Honduras is described and assigned to the subgenus Mollienesia. Poecilia hondurensis, new species, differs from all congeners in the combination of having tricuspid teeth on the inner of both jaws and lacking a prominent spine or hook on the gonopodium. Eleven geographically close congeners are treated in some detail, and a key is provided to identify all species occurring south of Mexico.
Agricultural areas are characterized by the replacement of native vegetation with plant crops or forage species. These create radically modified habitats for anurans, but in some areas frogs persist despite these changes. We undertook a three-year mark–recapture study of five breeding populations of the burrowing frog Heleioporus albopunctatus in the West Australian wheatbelt to quantify the variance in demographic parameters of a frog species in a highly modified, agricultural landscape. Recapture rates of frogs marked by toe-clipping were low and ranged from 0.05 to 0.45. Mark–recapture models estimated adult survival as ranging from 0.34 to 1. Survival was constant across years for four of five populations. One site exhibited both sex-biased and temporal variation in survival. Sex ratios and estimated population sizes fluctuated greatly between years. Available data on demography suggest H. albopunctatus is persisting in modified habitats.
The geographic range of the Timber Rattlesnake (Crotalus horridus) encompasses most of the eastern half of the United States. Although the overall diet composition of C. horridus has been well documented and has been reported to be very broad, local population variation has not been studied. We examined the diet and foraging behavior of C. horridus from four separate populations in Pennsylvania and New Jersey. A total of 253 prey items from scat samples, stomach samples, and field observation were identified to species or family level. Although voles (Myodes gapperi) and mice (Peromyscus spp.) comprised the bulk of the diet in all populations, relative prey species frequency differed significantly among the four populations. These data indicate that the food habits of C. horridus varied widely even within relatively small geographic distances. Comparisons with small mammal trapping data further suggest that the diet composition of this ambush predator may not simply reflect the availability of prey species. Radiotelemetric observations of C. horridus further indicate differing frequencies of log-oriented foraging behavior among the study sites. Analysis of body posture revealed an alternative ambush foraging posture (non-log-oriented posture) which also exhibited variation in frequency among study sites. However, selected foraging habitats at all study sites were typified by a locally high density of fallen logs and other woody debris (6% of forest-floor cover/m2). These findings indicate geographic variation in the foraging ecology of C. horridus and suggest behavioral plasticity in foraging response to available prey.
The ability to predict the effects that new or modified roads will have on species or populations of conservation interest is critically important to protection efforts. We documented patterns of movement and spatial dispersion of two sympatric snake populations by radiotracking 34 Eastern Massasaugas (Sistrurus catenatus) and 13 Eastern Hog-Nosed Snakes (Heterodon platirhinos) over four years. The two species differed substantially in their movements (frequency, rate, tortuosity, distance) and ensuing spatial dispersion. Regardless of species, males were more vagile than female conspecifics during the mating season. The primary factors hypothesized to have generated the interspecific differences in movement and spatial dispersion were foraging mode, mating system, and reproductive mode. By combining our understanding of how these snakes used space with knowledge of their natural history and ecology, we examined which attributes of their spatial ecology might render S. catenatus and H. platirhinos most susceptible to road effects. For S. catenatus, our observations suggest that spatial fidelity and space use relative to hibernacula are the primary factors influencing the species' susceptibility to road effects. For H. platirhinos, tortuous and extensive movements, space use relative to hibernacula, and large spatial dispersion distances from hibernacula are likely the most important factors.
The reproductive characteristics of many tropical amphibian species are poorly known, and the populations of many of these species are in decline. They occur in a variety of habitats and microhabitats. We investigated the reproductive biology of a tropical salamander, Bolitoglossa paraensis, in mature forest habitat in the Gunma Ecological Park, in the Brazilian state of Pará. During 12 nocturnal surveys between December 2005 and May 2007, we collected 104 salamanders (59 females/45 males) in order to compare microhabitat use in adults and juveniles, and assess the reproductive condition of males and females in relation to body size. Maturity was determined in females by the presence of enlarged, yolk-rich follicles >1.5 mm in diameter, and in males by the presence of distinct mental glands. A total of 18 females and 14 males were considered adult (mature). Adult females were significantly larger and heavier than adult males. Microhabitat use was similar between adults and juveniles, with 67% of specimens being found on the upper surface of the leaves of broad-leaved understory plants at heights of 0.2–2.8 m above the ground. The remaining specimens were found on trunks and branches at heights of 0.5–2.2 m. Clutch sizes varied from 8 to 14 eggs, but there was no significant relationship with female body size (SVL). Adult males and females were active mainly during the rainy season. The abundance of adults was related significantly to precipitation levels, indicating greater activity levels during the rainy season. Bolitoglossa paraensis is similar to other tropical species of this genus in terms of sexual dimorphism and patterns of microhabitat use and reproductive biology.
Water chemistry and landscape data were analyzed from streams in the Atlantic Coastal Plain physiographic province in Maryland, USA, to identify patterns in the spatial distribution of the state rare Banded Sunfish (Enneacanthus obesus). Principal component analysis was used to assess patterns in the distribution of this species based on select environmental variables. Mantel tests were conducted to further assess the correlation of environmental variables with the distribution of Banded Sunfish in Maryland while accounting for spatial autocorrelation. The distribution of Banded Sunfish was correlated with acidic stream segments with high concentrations of dissolved organic carbon and higher proportions of forest and wetland landscapes in upstream catchments. Conservation of Banded Sunfish will require the preservation of acidic, blackwater habitats through the protection of natural forest and wetland landscapes and limiting of the potentially harmful impacts of agricultural practices and urbanization. Such practices would likely benefit other native fishes throughout the region as well.