Mating pattern variability among western toad (Bufo boreas) populations

Summary Breeding ecology and mating patterns of the western toad, Bufo boreas, were examined in three large explosively breeding populations in the Oregon Cascade Mountains. Two mating patterns occurred variably within and among the three populations. First, a large male mating advantage was observed in two of the three populations when data from all the days of data collection were combined. When each day of breeding was analyzed separately, there was a large male mating advantage on 3 of 5 days at one population, and mating was random on all days at the two other populations. The second mating pattern, positive assortative mating by size, was observed at two of the three populations. This pattern was found on separate days of breeding as well as when data from all days were combined at one population, and on only one day of breeding at the second population.In a survey of anuran amphibian mating patterns, intraspecific variation was found in 13 of 15 species, including the present study of the western toad. Intrapopulation variation in mating patterns among breeding years has been observed in 5 of 8 anurans, whereas within-site, within-year mating pattern variation has only been reported for the western toad. These results strongly suggest that anuran mating patterns are frequently neither species-specific nor population-specific attributes. Variable mating patterns were most commonly observed in explosively-breeding anurans. Explosive breeders may be susceptible to variable mating patterns because they may be more sensitive to fluctuations in environmental conditions, demographic parameters, and the intensities of intrasexual competition and mate choice.     

Patterns in diversity of anurans along an elevational gradient in the Western Ghats, South India

Aim To examine patterns in anuran species richness along an elevation gradient and identify factors that govern anuran species richness on a tropical elevational gradient. Location Sampling for anurans was carried out in Kalakad Mundanthurai Tiger Reserve (KMTR) in the southern Western Ghats, India. Methods Night‐time sampling for anuran species richness was carried out from 20 November 2004 to 20 April 2005, during the north‐east monsoon and dry seasons, using transects (50 × 2 m) and visual encounter surveys along the streams. The entire gradient was classified into thirteen 100‐m elevation zones. Sampling at the alpha (single drainage basin) level was carried out in the Chinnapul River drainage basin (40–1260 m a.s.l.) and at the gamma (landscape) level in four drainage basins. Additionally, published records were used to arrive at an empirical species richness (S) for the entire landscape. Mid‐Domain Null software was used to test for the possible influence of geometric constraints on anuran species at both the alpha and gamma levels. The influence of area under each elevation zone on empirical S was tested. The pattern in anuran species richness along the elevational gradient was investigated using: (1) species boundaries in each elevation zone and their habitat correlates, (2) abiotic factors as predictor variables, (3) mean snout vent lengths of anurans, and (4) correlation between the matrices of distance in the elevation zones based on microhabitat parameters and species composition. Cluster analysis on species presence–absence in the elevation zones was used to categorize the entire gradient into high, middle and low elevations. In these three elevation categories, pattern in composition of species was examined for endemism in Western Ghats–Sri Lanka biodiversity hotspot, uniqueness to an elevation zone, adaptations of adults and modes of breeding. Results Species richness at the alpha level increased linearly with elevation, while at the gamma level there were three peaks. Maximum species richness was observed at the highest elevation (1200 m) at both the alpha and the gamma levels. The observed patterns differed significantly from mid‐domain null predictions. The multi‐modal pattern in species richness was a consequence of overlapping species range boundaries. Soil temperature was the best single measure in explaining the majority of variation in species richness at the alpha level (r² = 0.846, P < 0.01). However, soil moisture was the best predictor when both the alpha and the gamma sites were pooled (r² = 0.774, P < 0.01). Anuran body size decreased with an increase in elevation. The highest proportions of endemic and unique species were found at high elevations (> 700 m). The proportion of arboreal anurans increased from low to high elevation. Anurans exhibiting direct development were predominantly found at high elevations. Main conclusions Geometric constraints did not influence anuran species richness along the elevational gradient. Overlapping range boundaries influenced species richness at the gamma level. Abiotic factors such as soil temperature and moisture influenced anuran species richness in the mountain range. The ‘Massenerhebung effect’ could be responsible for range restriction and endemism of anurans, differences in guilds and mode of reproduction. These findings highlight the importance of cloud forests for endemic anurans.     

The relative roles of adaptation and phylogeny in determination of larval traits in diversifying anuran lineages

I measured phenotypic traits important to the fitness of larval anurans to assess the relative roles of ancestral trait value and selective regime in determining present-day phenotypes. The positions of 14 species from three taxonomic families and three different habitats in a phenotypic space defined by 19 traits provided measures of taxonomic and ecological similarity. The distribution of phenotypic distances among species revealed that neither taxonomy nor habitat overwhelmingly determined phenotype. There appear to be multiple ways in which anurans can exploit pond types. However, the direction of phenotypic movement was not random from one species to the next. Independent contrasts revealed significant correlations in the evolution of traits that were consistent among lineages. These correlations reflected well-known trade-offs that result from functional relationships among the constituent traits. Although there is no simple pattern in the distribution of mean phenotypes across environments and lineages, the pattern of the evolutionary trajectories that created that distribution is consistent with a predictive theory of multivariate evolution.     

Does climate influence assemblages of anurans and lizards in a coastal area of north-eastern Brazil?

Environmental factors influence diverse assemblage features such as species abundances, richness, and nestedness. Amphibians and reptiles play important roles in terrestrial ecosystems, but there is still a lack of information about the assemblages of these animals in many regions. In this study, we aimed to understand how environmental factors influence the anurans and lizards assemblages from São Gonçalo do Amarante, Ceará, Brazil. Herpetofauna samplings were performed monthly in São Gonçalo do Amarante from January 2008 to May 2009, excluding April 2008. We sampled animals (anurans and lizards) using pitfall traps and active searches. The abundance and richness of lizards were positively related to temperature and negatively related to precipitation. Anuran assemblage was not influenced by precipitation, but its abundance was negatively influenced by temperature. Temperature generated a nested pattern in the lizard assemblage, but precipitation did not produce this pattern in anurans. Finally, our results reinforce the importance of environmental factors, mainly temperature, in structuring assemblages of anurans and lizards.     

Intraspecific relationships between resting and activity metabolism in anuran amphibians: influence of ecology and behavior

The aerobic capacity model, as well as other models for the evolution of aerobic metabolism and the origin of endothermy, requires a mechanistic link between rates of resting and activity oxygen consumption (VO2rest and VO2act). The existence of such link is still controversial, but studies with anuran amphibians support a correlation between VO2rest and VO2act at both the intraspecific and interspecific levels. Because results at the intraspecific level are based only on a few species, we test for the generality of a link between these two metabolic variables in anurans by studying the intraspecific correlational patterns between mass-independent VO2rest and VO2act in anurans. We focus on 21 Neotropical species from different geographical areas that include remarkable diversity in behavior and thermal ecology. Although uncorrelated, VO2rest and VO2act seem to be consistent among individuals. Diverse intraspecific phenotypic correlational trends were detected, indicating that the intraspecific relationships between VO2rest and VO2act might be very diverse in anurans. The three possible trends (positive, negative, and absent correlations) were observed and appeared to be predictable from ecological and behavioral variables that relate to evolutionary physiological shifts in anurans. Positive correlations between VO2rest and VO2act were more common in species with active lifestyles (e.g., intense vocal activity) and in species that call at low temperatures (e.g., winter or high-elevation specialists).     

Evolutionary trends in adrenal gland of anurans and urodeles

Morphological, histological, ultrastructural, and developmental research on the adrenal gland of several species of anurans and urodeles belonging to different families is presented. Urodeles show a large variability in adrenal glandular structure without a clear taxonomic pattern, although increased compactness of the gland and mingling of steroidogenic and chromaffin cells are found only in some neourodeles. In anurans the glandular pattern may be divided into two subtypes: one more medial and diffuse, which is observed in frogs of the more primitive families; the other more lateral and aggregated, as seen in the more advanced families. The adrenal gland therefore increases in its compactness and aggregation of chromaffin and steroidogenic tissues in the transition from primitive to advanced families, both in urodeles and anurans. Until the end of metamorphosis, morphogenesis of the gland is similar in all amphibians studied. This process is extended after metamorphosis in the advanced anurans, in order that the gland may reach its definitive position.     

Behavioural,ecological, and evolutionary aspects of diversity in frog colour patterns

The role of colours and colour patterns in behavioural ecology has been extensively studied in a variety of contexts and taxa, while almost overlooked in many others. For decades anurans have been the focus of research on acoustic signalling due to the prominence of vocalisations in their communication. Much less attention has been paid to the enormous diversity of colours, colour patterns, and other types of putative visual signals exhibited by frogs. With the exception of some anecdotal observations and studies, the link between colour patterns and the behavioural and evolutionary ecology of anurans had not been addressed until approximately two decades ago. Since then, there has been ever‐increasing interest in studying how colouration is tied to different aspects of frog behaviour, ecology and evolution. Here I review the literature on three different contexts in which frog colouration has been recently studied: predator–prey interactions, intraspecific communication, and habitat use; and I highlight those aspects that make frogs an excellent, yet understudied, group to examine the role of colour in the evolution of anti‐predation strategies and animal communication systems. Further, I argue that in addition to natural‐history observations, more experiments are needed in order to elucidate the functions of anuran colouration and the selective pressures involved in its diversity. To conclude, I encourage researchers to strengthen current experimental approaches, and suggest future directions that may broaden our current understanding of the adaptive value of anuran colour pattern diversity.     

Phylogenetic and regional variations in brain gangliosides of tetrapods.

1. Ganglioside patterns were analyzed from four neural tissues (medulla, midbrain, forebrain and retina) in a representative from each of the four tetrapod classes. 2. Regional variations in ganglioside patterns were noted within some species, but differences were greater across phylogenetic lines. 3. These results suggest that evolutionary history plays a greater role than neural differentiation in the expression of brain ganglioside patterns.     

Comparative phylogeography of two open forest frogs from eastern Australia

We investigated the phylogeography of two closely related Australian frog species from open forest habitats, Limnodynastes tasmaniensis and L. peronii , using mitochondrial ND4 sequence data. Comparison of our results with previous work on Litoria fallax allowed us to test the generality of phylogeographic patterns among non-rainforest anurans along the east coast of Australia. In general, there was no strong evidence for congruence between overall patterns of genetic structure in the three species. However, phylogenetic breaks congruent with the position of the Burdekin Gap were detected at some level in all species. As previously noted for closed forest taxa, this area of dry habitat appears to have been an important influence on the evolution of several open forest taxa. There were broad geographic similarities in the phylogenetic structuring of southern populations of L. peronii and L. tasmaniensis. Contrarily, although the McPherson Range has previously been noted to coincide geographically with a major mtDNA phylogenetic break in Litoria fallax this pattern is not apparent in L. peronii or L. tasmaniensis. It appears that major phylogeographic splits within L. peronii and L. tasmaniensis may predate the Quaternary. We conclude that phylogeographies of open forest frogs are complex and more difficult to predict than for rainforest taxa, mainly due to an absence of palæomodels for historical distributions of non-rainforest habitats.     

Geographic body size gradients in tropical regions: water deficit and anuran body size in the Brazilian Cerrado

A recent interspecific study found Bergmann's size clines for Holarctic anurans and proposed an explanation based on heat balance to account for the pattern. However, this analysis was limited to cold temperate regions, and exploring the patterns in warmer tropical climates may reveal other factors that also influence anuran body size variation. We address this using a Cerrado anuran database. We examine the relationship between mean body size in a grid of 1° cells and environmental predictors and test the relative support for four hypotheses using an AIC-based model selection approach. Also, we considered three different amphibian phylogenies to partition the phylogenetic and specific components of the interspecific variation in body size using a method analogous to phylogenetic eigen vector regression (PVR). To consider the potential effects of spatial autocorrelation we use eigenvector-based spatial filters. We found the largest species inhabiting high water deficit areas in the northeast and the smallest in the wet southwest. Our results are consistent with the water availability hypothesis which, coupled with previous findings, suggests that the major determinant of interspecific body size variation in anurans switches from energy to water towards the equator. We propose that anuran body size gradients reflect effects of reduced surface to volume ratios in larger species to control both heat and water balance.     

Double stimulation of the inner ear organs of an anuran species (Alytes cisternasii) with simple tonal advertisement calls

Midwife toads present one of the simplest calls in anurans, with the whole energy concentrated in a single band without frequency modulation. The tuning curves of the Iberian midwife toads Alytes cisternasii show the typical bimodal pattern in anurans, with two best excitatory frequencies at 0.412 kHz (corresponding to the amphibian papilla) and at 1.358 kHz (corresponding to the basilar papilla and matching the male call frequency). In this study, the hypothesis that complex calls arose in anurans because they were inherently more attractive to females, since they provided greater acoustic stimulation, was tested. However, our results indicate that splitting the call energy to stimulate both inner ear organs simultaneously, the male call is not more attractive to female midwife toads, but sometimes renders it unattractive. The biological role of the amphibian papilla is discussed in ecological and evolutionary terms.     

Activity Pattern of Polecats Mustela putorius L. in Relation to Food Habits and Prey Activity

The activity pattern of polecats Mustela putorius L. was studied by radiotracking five males and four females in the wetlands of western France from Jul. 1988 to Mar. 1992. Polecats were nocturnal throughout the year with no differences between males and females. The diel activity remained moderate (31 %). Seasonal food habits were characterized by the exploitation of anurans in spring, while rodents were preyed upon from summer to winter. Seasonal changes in the activity rhythm of polecats appeared synchronized with the activity of the main prey. It is suggested that the activity patterns exhibited in different periods of the year are a result of changes in feeding tactics.     

The amphibian octavo-lateralis system and its regressive and progressive evolution

The phylogenetic and ontogenetic changes in the octavolateralis system of sarcopterygian fish and tetrapods, presumed to be important for the formation of an amphibian auditory system, are reviewed. The lateral line system shows rudimentation of lines and loss of ampullary electroreceptors in many amphibians; in some amphibians it never develops. The metamorphic changes of the lateral-line system show different patterns in the different amphibian lineages with metamorphic retention in most urodeles and metamorphic loss in most anurans. The multitude of both ontogenetic and phylogenetic changes of the lateral line system among amphibians do exclude any prediction as to how this system might have changed in ancestral amniotes. The most important auditory epithelium of the tetrapod inner ear, the basilar papilla, seems to be primitively present in all tetrapods and Latimeria. In two amphibian lineages there is a trend towards rudimentation and loss of the basilar papilla. Only in the third order, the anurans, a tympanic ear develops and the inner ear shows a progressive evolution of the auditory epithelia. Together with the known differences in the periotic labyrinth of amphibians and amniotes, this scenario suggests a parallel evolution of the amniotic and anuran auditory periphery. All mechanoreceptive hair cells of the lateral line system and the inner ear appear to receive a common and bilateral efferent innervation. Among amphibians this pattern is represented only in some urodeles, whereas anurans show a derived pattern with loss of a bilateral component and presumably also of a common neuromast/inner ear component. Changes in the rhombencephalic nuclei which receive octavo-lateralis afferent fibers show a trend towards development of auditory nuclei only in the anuran lineage. The phylogenetic appearance of an auditory nucleus in this lineage coincides with the complete absence of formation of ampullary electroreceptors. In contrast, the earlier claim of a correlation between a metamorphic loss of the lateral line system and the formation of an auditory nucleus is not supported by more recent data: an auditory nucleus develops in anurans already prior to metamorphosis and is present in all anurans even when they retain the neuromast system. In anurans with a metamorphic loss of the neuromasts, the second order neurons degenerate as well. This independence of the auditory and the second order lateral line nuclei is further substantiated by their separate projection to other brain areas, like the torus semicircularis of the midbrain, and their functional properties.(ABSTRACT TRUNCATED AT 400 WORDS)     

Temporal Expression of HNK-1-Reactive Sulfoglucuronyl Glycolipid in Cultured Quail Trunk Neural Crest Cells: Comparison with Other Developmentally Regulated Glycolipids

Monoclonal antibody HNK-1 is an important marker for embryonic neural crest cells and some of their differentiated derivatives. We have identified 3-sulfoglucuronylneolactotetraosylceramide (SGGL-1) as one of the HNK-1 antigens present in cultures of trunk neural crest cells. This lipid was present at 2 days in vitro and increased in amount with time in culture. Other major HNK-1-reactive antigens present in the culture were glycoproteins of apparent molecular masses of 120, 180, and 200 kDa. The 180- and 200-kDa bands were present at 2, 7, and 17 days in vitro, whereas the 120-kDa band was present only at 17 days in vitro. Gangliosides GD3, LD1, and LM1 were also found in the cultures and exhibited distinct temporal patterns of expression. Ganglioside GD3 was present at all stages examined and its expression peaked at 7 days in vitro. In contrast, LD1 was present only at 2 days in vitro and was not detectable at later times. Ganglioside LM1 increased in amount with time in culture in a pattern similar to that seen for SGGL-1. Taken together, these results indicate that several HNK-1-reactive molecules are expressed in neural crest cultures in a temporally regulated manner along with several glycolipids that do not bear this epitope.     

The evolution of jumping in frogs: Morphological evidence for the basal anuran locomotor condition and the radiation of locomotor systems in crown group anurans

Our understanding of the evolution of frog locomotion follows from the work of Emerson in which anurans are proposed to possess one of three different iliosacral configurations: 1) a lateral‐bending system found in walking and hopping frogs; 2) a fore‐aft sliding mechanism found in several locomotor modes; and 3) a sagittal‐hinge‐type pelvis posited to be related to long‐distance jumping performance. The most basal living (Ascaphus) and fossil (Prosalirus) frogs are described as sagittal‐hinge pelvic types, and it has been proposed that long‐distance jumping with a sagittal‐hinge pelvis arose early in frog evolution. We revisited osteological traits of the pelvic region to conduct a phylogenetic analysis of the relationships between pelvic systems and locomotor modes in frogs. Using two of Emerson's diagnostic traits from the sacrum and ilium and two new traits from the urostyle, we resampled the taxa originally studied by Emerson and key paleotaxa and conducted an analysis of ancestral‐character state evolution in relation to locomotor mode. We present a new pattern for the evolution of pelvic systems and locomotor modes in frogs. Character analysis shows that the lateral‐bender, walker/hopper condition is both basal and generally conserved across the Anura. Long‐distance jumping frogs do not appear until well within the Neobatrachia. The sagittal‐hinge morphology is correlated with long‐distance jumping in terrestrial frogs; however, it evolved convergently multiple times in crown group anurans with the same four pelvic traits described herein. Arboreal jumping has appeared in multiple crown lineages as well, but with divergent patterns of evolution involving each of the three pelvic types. The fore‐aft slider morph appears independently in three different locomotor modes and, thus, is a more complex system than previously thought. Finally, it appears that the advent of a bicondylar sacro‐urostylic articulation was originally related to providing axial rigidity to lateral‐bending behaviors rather than sagittal bending. J. Morphol., 2011. © 2010 Wiley‐Liss, Inc.     

Biogeographic area relationships of lowland Neotropical rainforest based on raw distributions of vertebrate groups

Hypotheses of the historic biogeography of Neotropical anurans inhabiting lowland forests were generated using Parsimony Analysis of Endemicity. In order to establish comparisons with the biogeographical patterns of other vertebrates, previous cladistic analyses reported in the literature (for lizards and primates) were extended and reanalysed to match the geographical scope of the anuran analysis. Cladistic analysis of the distribution of 335 anuran species at 14 localities showed two regions that form a basal dichotomy: (1) Central America + Choco and (2) Amazon Basin + Brazilian Atlantic Forest. This result is interpreted as the first vicariance event that separated lowland Neotropical rainforests into Cis-Andean (east from the Andes) and Trans-Andean (west from the Andes) areas. Within the Cis-Andean localities, the earliest separation occurred between the Amazon Basin and the Brazilian Atlantic Forest. Within the Amazon Basin, three distinctive clusters are defined: (1) Belem, (2) Guianan Region, and (3) Upper Amazon Basin. Data sets on the distribution of anurans, lizards, and mammals have strong cladistic signal. Strong congruence exists among the area cladograms of anurans, lizards, and primates. All of them have, or at least did not conflict with: (1) a basal separation between Cis- and Trans-Andean regions, (2) a Central American clade, (3) the Choco Region is sister to the Central American clade, (4) an Amazon Basin clade, (5) an Upper Amazon Basin clade, and (6) a Guianan clade. The area cladograms are dichotomous and therefore do not support biogeographic theories that hypothesize simultaneous isolations of biotas in the Neotropics.     

A comparison of energy substrates and reproductive patterns of two anurans. Acris crepitans and Bufo woodhousei

The seasonal pattern of carcass, liver and ovary lipid and liver non-lipid mass was examined in the cricket frog, Acris crepitans, and Woodhouse's toad, Bufo woodhousei. Reproductive patterns were also studied. The over-winter reduction of body lipid and liver non-lipid material was attributed to metabolism in Acris crepitans. Male, but not female, Bufo woodhousei exhibited seasonal variation in lipid stores that was attributable to metabolism. Females, but not males, showed seasonal variation in liver non-lipid mass and quantified liver glycogen. Females of both species mobilized body lipid during the period of ovarian development; however, an inverse relationship between fatbody mass and ovary mass was evident for Acris, only. Female Acris crepitans depleted all ovarian follicles prior to brumation; however, Bufo woodhousei retained enlarged follicles throughout the year. Variation in metabolic substrate use between species was related to the differences in reproductive patterns exhibited by the two anurans. These variations in reproductive strategy represent adaptations that enhance the survivability of different species in dissimilar habitats.     

Selecting a Hiding Place: Anuran Diversity and the use of Bromeliads in a Threatened Coastal Sand Dune Habitat in Brazil

Among vertebrates, anuran amphibians represent the highest number of species associated with bromeliads and possess a range of ecological, behavioral, and morphological specializations to life in these plants. Despite the importance of bromeliads as biodiversity amplifiers, and their diversity in some habitats, studies of the relationship between anurans and these plants are scarce in Brazil. Here, we investigated the way anurans select and use bromeliads in a threatened coastal habitat. We analyzed data from 23 standardized samples of the anurans associated with the bromeliad Neoregelia cruenta in the Restinga de Maricá, State of Rio de Janeiro, Southeastern Brazil. We found nine anuran species using these bromeliads, representing the highest richness reported for a Brazilian restinga. We identified a general pattern of bromeliad usage, where plants located at the edges of scrub patches (exposed to the sun) were more frequently occupied by anurans than those located more to the center (in the shade). There is strong evidence of an active selective process based on the quality of the water stored in the rosette, which differs between plants depending on their position in the scrub patch. Although the number of individuals varied during the period of study, the frequency of bromeliads used was constant, indicating that plant occupation follows a regular pattern throughout the year. Furthermore, the high frequency of bromeliads used by anurans during the whole year highlights the importance of considering these plants in developing conservation programs concerning the protection of anurans.