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Calling site selection by male Boana punctata (Anura: Hylidae)
Abstract and Figures
Amphibian species require specific conditions for reproduction, such as cover structures and shelters, in both aquatic and terrestrial habitats, which directly influence reproductive success. A careful selection of calling sites is an important process, driving life-history strategies and tactics in amphibians. Despite this, a significant knowledge gap on how different variables modulate amphibian microhabitat selection processes is noted. Thus, we aimed to: (1) describing the microhabitat use of adult neotropical Boana punctata males during the breeding season; and (2) quantitatively analyzing the selection process of five resource variables (i.e., vegetation cover, vegetation density, vegetation height, water depth, and distance to the water shore). We then compared the microhabitat selection of males that achieved spawning and that of males that did not achieve spawning. To quantify selection, we used a resource selection function approach, applying a case/control design where the calling site used by each male was paired to eight surrounding, unused locations. We found that males selected microhabitats with higher vegetation than surrounding areas for reproduction, which suggests territorialism, and selected microhabitats slightly (∼ 30 cm) inside the assessed ponds. Males also acted randomly with regard to the other variables, not influencing the males' microhabitat selection. Microhabitat use of males successful in obtaining females to spawn was similar to that of males exhibiting mating failure. In addition to being of ecological interest, our study highlights that preserving tall vegetation and the ponds' shores is important for the conservation of existing B. punctata urban populations.
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The authors studied the influence of three environmental traits on the microhabitat selection of Ameiva ameiva (Linnaeus, 1758), in the Brazilian Pantanal, an environment with a marked effect of seasonality, i.e., alternating periods of flooding and falling dry. microhabitat selection was assessed in the dry season using a Resource selection Function (RsF) and Conditional Logistic Regression (CLR) analysis. twenty-nine adult individuals of A. ameiva were observed. the average temperature in places where individuals occurred was 36 °C (ranging from 27 °C to 51 °C; sd = 6.8 °C). the pattern of the temperature of the substrate on which A. ameiva was observed showed peaks, occurring alternatively either at very high but also milder temperatures along its daily activity period. the CLR model revealed that none of the studied environmental variables (substrate temperature, type of substrate or sun exposure) significantly affected the probability of occurrence of Ameiva lizards at a particular point (P = 0.11, P = 0.69, P = 0.87, respectively). Regarding the sun exposure situation the qualities full sun, shade and filtered sun were distinguished, the substrate type comprised the parameter values grass, leaflitter and exposed soil. the results suggest that A. ameiva is not a microhabitat specialist, at least during the dry season in the Pantanal of Brazil.
Research in urban ecology is growing rapidly in response to the exponential growth of the urban environment. However, few studies have focused on tropical megacities, and on the interplay between predators’ habitat selection and human socio-economic aspects, which may mediate their resilience and coexistence with humans. We examined mechanisms of breeding habitat selection by a synanthropic raptor, the Black Kite Milvus migrans, in Delhi (India) where kites mainly subsist on: (1) human refuse and its associated prey-fauna, and (2) ritualised feeding of kites, particularly practised by Muslims. We used mixed effects models to test the effect of urban habitat configuration and human practices on habitat selection, site occupancy and breeding success. Kite habitat decisions, territory occupancy and breeding success were tightly enmeshed with human activities: kites preferred areas with high human density, poor waste management and a road configuration that facilitated better access to resources provided by humans, in particular to Muslim colonies that provided ritual subsidies. Furthermore, kites bred at ‘clean’ sites with less human refuse only when close to Muslim colonies, suggesting that the proximity to ritual-feeding sites modulated the suitability of other habitats. Rather than a nuisance to avoid, as previously portrayed, humans were a keenly-targeted foraging resource, which tied a predator’s distribution to human activities, politics, history, socio-economics and urban planning at multiple spatio-temporal scales. Many synurbic species may exploit humans in more subtle and direct ways than was previously assumed, but uncovering them will require greater integration of human socio-cultural estimates in urban ecological research.
Resource partitioning is considered one of the main processes driving diversification in ecological communities because it allows coexistence among closely related and ecologically equivalent species. We combined three complementary approaches, i.e. the evaluation of foraging behaviour, diet composition and nutritional condition (RNA:DNA ratio), to assess feeding by two closely related (sister) butterflyfishes that are syntopic in Puerto Rico. Chaetodon capistratus had a higher abundance and higher bite rate and selected octocorals and hard corals for feeding, whereas Chaetodon striatus fed preferentially on sandy substrates. Cnidarians and polychaetes were the most representative diet items for both species, but C. capistratus preferred the former (Feeding Index of 74.3%) and C. striatus the latter (Feeding Index of 60.4%). Similar RNA:DNA ratios for both species suggest that, although they differ in feeding rates and diet, C. capistratus and C. striatus have similar nutritional fitness. Therefore, these species are both zoobenthivores but show clear differences in their substrate selection. The differences in the use of foraging substrate by C. capistratus and C. striatus , despite their close phylogenetic relationship and similar diets, suggest that these species coexist by resource partitioning.
Warm or cool ambient temperatures during winter generate plasticity in the within-year timing of oviposition or breeding phenology shifts through the use of a reaction norm in many riverine ectotherms, but within-year timing of oviposition in Hynobius kimurae (Caudata: Hynobiidae) is predicted to be constant at different water temperatures of a mountain stream. To clarify this difference, by experimentally controlling water temperatures from fall to spring and thus changing durations of aquatic hibernation and dates of oviposition, we determined whether oviposition is more advanced when water temperatures increase earlier than usual or is more delayed when water temperatures increase later than usual. Oviposition was more delayed than usual with earlier exposure to high water temperatures during spring and was earlier than usual with exposing to higher water temperatures during hibernation. Days from submergence to oviposition were responsive to cumulative daily water temperatures from submergence to oviposition within a population. A rate of increase in days from submergence to oviposition was different between populations but was constant within a population even if minimal water temperatures varied each year. When running a program of a Markov chain Monte Carlo generalized linear mixed model for Bayesian computation to interpret confounding effects, neither different treatments nor different years statistically affected days from submergence to oviposition. These results suggest that a biological clock exits for days from submergence to oviposition in H. kimurae, which could allow survival in situations with either warmer or cooler environments.
In this paper we present information on fluorescent frogs that will be of use to interested researchers. We describe practical details and provide new data on the phenomenon in Boana punctata, while reporting for the first time its occurrence in the closely related B. atlantica. Both species leave persistent fluorescent marks on the substrate in field and lab conditions, the biological role of which, if any, remains unknown. We discuss briefly the heuristic criteria employed to identify other anuran species most likely to be fluorescent—at least in a similar way to that described in B. atlantica and B. punctata—and provide a list of 281 species in seven families (Arthroleptidae, Centrolenidae, Hemiphractidae, Hylidae, Hyperoliidae, Mantellidae, and Rhacophoridae) that should be tested for the occurrence of fluorescence. Finally, we discuss some general aspects related to anuran coloration, fluorescence, and criteria to assess its biological role, if any, commenting on the role of pteridins and hypothetical situations where these could lead to fluorescence in a different way than how we see it in B. atlantica and B. punctata.
Assembly of ecological communities is important for the conservation of ecosystems, predicting perturbation impacts, and understanding the origin and loss of biodiversity. We tested how amphibian communities are assembled by neutral and niche-based mechanisms, such as habitat filtering. Species richness, β-diversities, and reproductive traits of amphibians were evaluated at local scale in seven habitats at different elevation and disturbance levels in Wisui Biological Station, Morona-Santiago, Ecuador, on the foothills of the Cordillera del Kutukú; and at regional scale using 109 localities across evergreen forests of Amazonia and its Andean slopes (0–3,900 m a.s.l.). At local scale, species composition showed strong differences among habitats, explained mainly by turnover. Reproductive modes occurred differently across habitats (e.g., prevalence of direct developers at high elevation, where breeding in ground level water disappears). At regional scale, elevation was the most important factor explaining the changes in species richness, reproductive trait occurrences, and biotic dissimilarities. Species number in all groups decreased with elevation except for those with lotic tadpoles and terrestrial reproduction stages. Seasonality, annual precipitation, and relative humidity partially explained the occurrence of some reproductive traits. Biotic dissimilarities were also mostly caused by turnover rather than nestedness and were particularly high in montane and foothill sites. Within lowlands, geographic distance explained more variability than elevation. Habitat filtering was supported by the different occurrence of reproductive traits according to elevation, water availability, and breeding microhabitats at both scales, as well as other assembly mechanisms based in biotic interactions at local scale. Human-generated land use changes in Amazonia and its Andean slopes reduce local amphibian biodiversity by alteration of primary forests and loss of their microhabitats and the interaction network that maintains their unique amphibian assemblages with different reproductive strategies.
Significance
In this interdisciplinary study, we report naturally occurring fluorescence in amphibians; specifically, in a common South American tree frog. We show that fluorescence is traceable to a class of compound that occurs in lymph and skin glands. Our study indicates that in our model species, in low-light conditions, fluorescence accounts for an important fraction of the total emerging light, largely enhancing brightness of the individuals and matching the sensitivity of night vision in amphibians. These findings open an exciting perspective into frog visual physiology and ecology and into the role of fluorescence in terrestrial environments, where classically it has been considered irrelevant.
The selection of breeding habitat has broadscale implications for species distributions and community structure and smaller-scale ramifications for offspring survival and parental fitness. In anurans, offspring deposition is a decisionmaking process that involves the assessment of multiple factors at a breeding site, including the presence of predators and competitors. Evolutionary theory predicts that adult anurans should seek to minimize the risk of predation to offspring, reduce the pressure of competition, and maximize offspring survival. Many experimental studies have demonstrated the ability of anurans to assess deposition sites for predation and competition and to choose accordingly, but our understanding of the various ecological factors involved in site choice and the broader consequences of choice is still limited. Here, we review and synthesize the literature on the influence of predators and competitors on anuran deposition behavior. We highlight current gaps in our understanding of this topic and outline future avenues of research.
The selection of appropriate calling sites is a key aspect in the reproductive strategy of nearly all anurans. We evaluated if males of the South American tree frog (Hypsiboas pulchellus) select calling sites in undisturbed subtropical wetlands based on specific habitat cues. The study was designed to represent a snapshot of the male calling activity under low densities of intra- and interspecific competitors and little variation of climatic conditions. We characterized calling sites by measuring the vegetation attributes and flood levels of calling sites occupied by 59 males and comparing them to available microhabitats. We found that males exhibit some degree of selectivity for calling sites, often selecting microhabitats with greater density of vegetation < 50 cm tall. Calling site selection was not affected by water depth or area flooded. Most individuals vocalized in sites near the ground (≤ 25 cm), a pattern that is the contrary to that expected to maximize sound propagation. We suggest that, due to the open habitat of the studied area, the choice of calling sites is more related to the need for shelter from predation and avoidance of desiccation and heat loss than to bioacoustic performance.
In many species, females may be particularly selective about the expected direct benefits of choosing a potential mate or the male's genetic contribution to their offspring. Growing evidence suggests that female choosiness can also be influenced, for instance, by local abiotic factors, the social environment or the presence of heterospecifics. In amphibians that breed in highly temporary ponds with limited trophic resources (such as the yellow-bellied toad, Bombina variegata), competition during larval development may have a strong impact on the fitness of offspring. Accordingly, one might expect females to apply hierarchical decision making, balancing intraspecific competition risks during larval growth against the relative indirect benefits associated with the quality of the male. To investigate this issue, we conducted experiments in seminatural enclosures to test whether the preference of yellow-bellied toad females for good call attractiveness (determined by fundamental frequency) is affected by the risk of larval competition within the pond occupied by the callers. Overall, our results showed that females have a preference for low-frequency calls when prior information does not enable them to assess the relative quality of ponds. However, when prior information enables females to unambiguously determine relative pond quality, females appear to apply hierarchical decision making in which the quality of a pond prevails over call cues related to the quality of the male.
Animals can encode multiple messages using acoustic communication in diverse behavioral contexts. Although the anuran advertisement call might convey different messages to males and females, the role of the calling microhabitat type in intra- and intersexual behavior is unclear. We report advertisement call differences in six of the seven acoustic parameters analyzed for the Brazilian hylid frog Hypsiboas atlanticus, depending on the calling microhabitat type (water or perch). These call differences were aurally distinctive and enabled us to count males calling during the reproductive period, estimating abundance of calling males per microhabitat throughout a given night. We used playback tests to determine whether male behaviors vary as a function of the microhabitat type and whether males stimulated by calls from other males in different microhabitats alter their behavior and acoustic parameters. Advertisement calls were influenced by male body size and temperature. The temperature increased or decreased the call’s parameters according to microhabitat type. Playback stimulus promoted acoustic responses depending on the calling microhabitat, playback type, or both. Males calling from perches also emitted territorial calls and visual displays. There was an inverse relationship between the abundance of perched males and those in the water throughout the night. Our results indicate that the calling microhabitat has an impact on the advertisement call function in H. atlanticus: an advertisement call sent from a perch shows a predominant role in territory establishment, whereas an advertisement call sent from males in water might have a predominant role in attracting mates for reproduction.
To evaluate the effects of calling site on call degradation, we broadcast synthetic advertisement calls of male gray treefrogs through forest, over open terrain, and across pond water. Calls were recorded at distances of 1, 2, 4, 8, 16, and 32 m. We varied speaker and microphone heights for a total of five elevation combinations ranging from surface level to a height of 1.5 m. We quantified structural degradation in recorded calls using “∆V,” a measure of relative sound energy in call pulses and interpulse intervals. A subset of recorded calls was used in two-speaker discrimination tests with females. Finally, we examined male selection of perch height by recording locations of calling males on ladder-like trellises positioned around the periphery of a breeding pond. We found the greatest degradation for calls broadcast through forest followed by calls transmitted across open terrain and then pond water. At relatively small source-receiver separations, elevation had only small effects on degradation. However, for separations greater than 4 m (especially through forest), elevation had a significant impact on ∆V—with calls broadcast and recorded near the substrate particularly vulnerable to degradation. Choice tests demonstrated that such levels of degradation could significantly reduce a male’s attractiveness. This may, in part, explain why males only seldom called from low rungs of trellises.
Modern ecological research often involves the comparison of the usage of habitat types or food items to the availability of those resources to the animal. Widely used methods of determining preference from measurements of usage and availability depend critically on the array of components that the researcher, often with a degree of arbitrariness, deems available to the animal. This paper proposes a new method, based on ranks of components by usage and by availability. A virtue of the rank procedure is that it provides comparable results whether a questionable component is included or excluded from consideration. Statistical tests of significance are given for the method. The paper also offers a hierarchical ordering of selection processes. This hierarchy resolves certain inconsistencies among studies of selection and is compatible with the analytic technique offered in this paper.
Anuran amphibians are known to employ acoustic signals as the principal form to access potential mates, while recent studies have highlighted the importance of multiple cues during courtship. Hypsiboas punctatus is a hylid species in which males emit advertisement calls and have sexually dimorphic skin glands (SDSGs). However, knowledge on the re-productive biology of this species is very limited. We present the first systematic field-observational study on the behaviour of H. punctatus, which was complemented by observations under laboratory-controlled conditions. Males exhibit a territo-rial behaviour as is evidenced by site fidelity, aggressiveness against male intruders (usually involving fights), and signalling behaviour. We found that female choice would be operating at two different levels, which we defined as Initial Exploration (I.E.) and Proximate Exploration (P.E.). These levels would be guided by acoustic signals in I.E., while tactile and/or chemi-cal signals (considering the presence of SDSGs) would be more important in P.E. We also provide descriptions of vocal in-teraction between males, amplexus, and egg clutch. We suggest that SDSGs located at the mental gland may be important in delivering sexual pheromones to the female during amplexus. Finally, our results are compared to similar behaviours that have been described for related species, and discussed in terms of the probable existence of multimodal communication.
ABSTRACT.—Male Hypsiboas punctatus emit seven different types of calls: three consist of repeated trains of notes, and four are single-note calls with frequency modulation. Behavioral observations allowed assigning the calls to specific functions: (1) and (2) advertisement calls (short and long duration), (3) territorial signaling, (4) courtship interactions, (5)–(7) aggressive interactions (aggressive, fighting, and release calls). All calls consist of a single note and possess harmonic structure. The harmonic structure from the advertisement call suggests a missing fundamental frequency. Advertisement calls exhibit inter- and intraindividual variation in the dominant frequency. Our results indicate that previous comparisons among vocalizations of H. punctatus were based on different types of calls.
A total of 112 Frog species of the Iquitos Region are characterized, according to ist life characteristics, taxonomy, Habitat and biology, as known. Comparisons with similar species are made, to avoid confusion. Tadpoles, calls and Food Habits are also provided. Full - Color plates are also presented to help the amateur and experienced scientists to identify the species.
The vocalization behaviour of Leptodactylus albilabris was investigated using field playback experiments. To assess the response of males to pre-recorded natural ‘chirp’ (advertisement call) and natural ‘chuckle” (aggressive call) stimuli of gradually increasing broadcast intensity, three parameters (intensity, dominant frequency and repetition rate) of the chirp call were analysed. Of the males tested, 69% showed a significant increase in chirp intensity with increased levels of both stimulus types. In response to playback of the chirp stimulus, males actively modified the dominant frequency of their chirp calls over a mean range of 91·42 Hz, and in one case as much as 400 Hz. Moreover, 12 of 17 males shifted the frequency of their call towards the dominant frequency of the chirp stimulus (2175 Hz) by either increasing or decreasing the dominant frequency of their chirp calls. In response to the natural chuckle stimulus, 83% of the males showed either a decrease or no significant change in the dominant frequency of their chirps. All eight males for which both the chirp frequency and intensity were analysed and that showed an increase in chirp intensity also showed a concomitant increase in chirp dominant frequency. These results are the first to document quantitatively the plasticity of advertisement call intensity and dominant frequency in an anuran. The possible effects of advertisement call modification on male mating success in L. albilabris is discussed.
Köppen's climate classification remains the most widely used system by geographical and climatological societies across the world, with well recognized simple rules and climate symbol letters. In Brazil, climatology has been studied for more than 140 years, and among the many proposed
methods Köppen's system remains as the most utilized. Considering Köppen's climate classification importance for Brazil (geography, biology, ecology, meteorology, hydrology, agronomy, forestry and environmental sciences), we developed a geographical information system to identify
Köppen's climate types based on monthly temperature and rainfall data from 2,950 weather stations. Temperature maps were spatially described using multivariate equations that took into account the geographical coordinates and altitude; and the map resolution (100 m) was similar to the
digital elevation model derived from Shuttle Radar Topography Mission. Patterns of rainfall were interpolated using kriging, with the same resolution of temperature maps. The final climate map obtained for Brazil (851,487,700 ha) has a high spatial resolution (1 ha) which allows to observe
the climatic variations at the landscape level. The results are presented as maps, graphs, diagrams and tables, allowing users to interpret the occurrence of climate types in Brazil. The zones and climate types are referenced to the most important mountains, plateaus and depressions, geographical
landmarks, rivers and watersheds and major cities across the country making the information accessible to all levels of users. The climate map not only showed that the A, B and C zones represent approximately 81%, 5% and 14% of the country but also allowed the identification of Köppen's
climates types never reported before in Brazil.
Social behavior of Hypsiboas albomarginatus was studied in the Atlantic rain forest, Municipality of Ubatuba, in the north coast of the State of São Paulo, southeastern Brazil. Vocalizations of H. albomarginatus are described, including contexts in which they were emitted and temporal and spectral parameters differentiating advertisement from aggressive calls. Dominant call frequency was inversely correlated with male length and body mass but not with environmental temperature. Number of pulses per note was not correlated with any variable, and advertisement call amplitude was influenced by temperature and time. During chorus aggregation, males interacted acoustically by emitting advertisement calls in antiphony, or by emitting aggressive calls. Some disputes among males culminated in physical combat; males performed kicks and slaps on rivals' heads, in an apparent attempt to dislodge rivals from perches. Visual signals were also displayed during conflicts between males, contributing to an escalation of aggressive behavior. Visual signals were not recorded during courtship between males and females but may help in the accurate localization of the signaling male during aggressive interactions.
Breeding success of frogs depends, among other factors, on male and female habitat choices, which may be based in part on environmental features that aid offspring survivorship and development. Frogs can respond to habitat features in varied scales, including types of bodies of water and microhabitats within them, and the correspondence between male and female choices may contribute to a successful reproduction. We compared habitat and microhabitat choices by males and females of a Scinax species from the catharinae clade, focusing on microhabitat selection by both sexes, including variation between dry and wet seasons. We also compared the distribution of males and females across a stream size gradient and related their abundance with numbers of tadpoles in each stream to assess successful breeding. We found males and females to be similar in microhabitat preferences, but their abundances did not correlate across streams. Male abundance, however, correlated with number of tadpoles, including that number of females may have been underestimated due to their shorter permanence at breeding sites or lower detection probability. Competition and predation did not seem to influence distribution of Scinax gr. catharinae among streams. Male and female Scinax gr. catharinae seem to show highly coordinated responses when selecting breeding habitats and microhabitats, apparently resulting in high breeding success at the study site.
SYNOPSIS. Acoustic signals transmitted over large distances differ significantly from those emitted by the signaler. Acoustic signals degrade in amplitude, spectral and temporal structure as they propagate through theenvironment. A great deal of work on acoustic communication is aimed at understanding the selective forces imposed by the environment on animal signals. I will discuss the physical constraints the environment puts on acoustic communication, and then discuss similarities in communication by anurans and insects that relate these environmental constraints to their signaling systems. Lastly, I show how changes in signals during propagation relate to changes in signal perception during phonotaxis, and thus, how propagation relates to mate choice and sexual selection.
Temporal patterns of anuran reproduction fall into two broad categories: prolonged breeding and explosive breeding. The spatial and temporal distribution of females determines the form of malemale competition. Males of explosive breeders in dense aggregations engage in ‘scramble competition’, attempting amplexus with every individual and struggling among themselves for possession of females. Males of prolonged breeders usually call from stationary positions to attract females and often maintain some sort of intermale spacing. Many aspects of vocal behaviour and chorus organization can be viewed as consequences of intrasexual competition. Males of some prolonged breeders defend allpurpose territories, oviposition sites, or courtship areas against conspecific males. Males with high quality territories may enhance their attractiveness to females and obtain several mates in one season. The social organization of some species resembles the lek behaviour of other vertebrates. Males or females of some tropical species care for eggs and tadpoles, but the evolution of parental care has not yet been studied in detail.
The use of space by anuran amphibians during reproductive activities was studied at eight forest streams in the Reserva Particular do Patrimônio Natural Santuário do Caraça, southeastern Brazil. Identified microhabitats were classified into 18 types based on substrate and height above ground/water. A total of 440 individual anurans of 19 species was recorded in these microhabitat types. Electivity indices were calculated for the three most abundant species and indicated that specimens actively selected microhabitats. Species with broad niches (generalists) did not occur in more streams than species with narrow niches (specialists), and streams with higher species richness did not contain more specialists. Species showed high levels of overlap in microhabitat use, which were not related to the number of co‐occurring species. The distribution patterns observed in the studied anuran assemblages likely reflect specific reproductive preferences and colonization abilities rather than the result of competitive pressures.
We assessed the role of habitat structure in the outcome of predation by measuring how aquatic vegetation influences predation rates of water bugs (Belostoma oxyurum (Dufour, 1863), Hemiptera, Belostomatidae) on tadpoles of Dendropsophus minutus (Peters, 1872) and Scinax curicica Pugliese, Pombal, and Sazima, 2004 (Anura, Hylidae). Considering that previous studies have shown that some tadpole species preferentially use microhabitats with aquatic vegetation at sites in southeastern Brazil, we hypothesized that these tadpoles may select such complex microhabitats because they can offer some protection against co-occurring predatory aquatic insects. We used field enclosures containing tadpoles of D. minutus and S. curicica and one predator (B. oxyurum), placed on natural substrata in sites both with and without aquatic vegetation, according to treatment. We measured the combined effects of predation and habitat structure on the survivorship of tadpoles, monitoring each enclosure daily during 10 days to survey surviving tadpoles. Treatments with predators reduced tadpole survivorship significantly in relation to controls for both tadpole species. The interaction between predator and vegetation was also significant, predation rates being lower when vegetation was present.
Oviposition-site choice is a major maternal effect by which females can affect the survival and phenotype of their offspring. Across oviparous species, the ultimate reasons for females' selection of oviposition sites often differ. We present six hypotheses that have been used to explain nonrandom oviposition-site choice in insects, fish, amphibians, reptiles, and birds: (a) maximizing embryo survival, (b) maximizing maternal survival, (c) modifying offspring phenotype, (d) proximity to suitable habitat for offspring, (e) maintaining natal philopatry, and (f) indirect oviposition-site choice via mate choice. Because these hypotheses differ in their relevance across oviparous taxa, each hypothesis must be tested to ensure accurate understanding of the ultimate reason behind oviposition-site choice in a particular taxon. By presenting the major hypotheses for oviposition-site choice as they relate to diverse oviparous animals, we nonetheless illustrate particular trends across animal taxa, while highlighting...
Phyllomedusa burmeisteri was studied during breeding aggregations in a temporary pond in southeastern Brazil. Males were territorial and aggressive. Behavioral patterns exhibited by them included acoustical and visual communication, chase, and wrestling, the latter when the intruder did not retreat with the preceding threats. Females also performed visual displays, however in different contexts, before approaching toward a calling male. The vocal repertoire of P. burmeisteri consisted of two types of advertisement call (short type and long type), territorial call and encounter call. Information about spatial-temporal distribution, courtship, and mating behavior are presented.
Trade-offs shaping behavioral variation are often influenced by the environment. We investigated the role that the environment plays in mediating trade-offs using a widespread frog with a conspicuous mating display, Pseudacris crucifer. We first demonstrated, using playback and desiccation experiments, that calling site selection involves a trade-off between sound transmission and desiccation. We then determined the influence of local environmental conditions on the intensity of the trade-off by examining range-wide behavioral and environmental data. We showed that the benefit of improved call transmission is positively influenced by vegetation density and ground cover. Behavioral data are consistent with this relationship: sites with a greater transmission benefit have increased prevalence of arboreally calling males. We also found that the prevalence of arboreal calling behavior increases with relative humidity and air temperature, suggesting an influence of these environmental variables on the desiccation cost of arboreal calling. This study provides a clear example of the role of the environment in mediating trade-off intensities and shaping critical behavioral traits.
Local environment mediates the intensity of a trade-off associated with arboreal calling behavior in a treefrog. Combining observational and experimental approaches, we show that arboreal calling behavior increases the transmission of a mating call while potentially subjecting individuals to a rate of desiccation six times greater than terrestrial calling. Local environmental conditions influence both the benefit and the cost of this trade-off, subjecting different populations to varying trade-off intensities and shaping arboreal calling behavior.
Pristimantis bacchus is an endangered terrestrial frog, endemic to cloud forests of the northern part of the Cordillera Oriental in the Colombian Andes. The knowledge of its reproductive biology and microhabitat use can offer important information for future conservation programs. We evaluated the reproductive activity and microhabitat use for both sexes, and selection of calling sites by males during rainy and dry seasons. Individuals of all reproductive conditions were observed throughout the sampled months; however, we observed a higher abundance of frogs during the first rainy season, after the driest months of the year. Thus, this population seems to have continuous reproductive activity, with an apparent peak at the onset of the first rainy season of the year. There were differences in the microhabitat use between sexes, between adults and juveniles, and between non-reproductive and reproductive females. Males use a wider variety of substrates at higher perches, while females were mainly found on leaf litter and over leaves at low heights; however, ovigerous females mostly occupied substrates above 120 cm. Juveniles were less abundant than adults, and occupy low substrates, mostly at forest litter. Two selection models evaluated the preference for calling sites, related to physiological requirements of humidity and for vocal sound dispersion. Males preferred to vocalize on perches at heights among 41-120 cm and with a vegetal structure that maintains high humidity, avoiding desiccation, and reducing exposure to predators. Therefore, intrapopulation variation in microhabitat use in this species is related to age, sex, reproductive condition, and physiological requirements.
Our aim was to disentangle the effects of different heat sources and the non-thermal properties of the substrate in the microhabitat choices of two lizard species living in savanna habitats of central-western Brazil: the teiid Ameivula aff. ocellifera (N = 43) and the tropidurid Tropidurus oreadicus (N = 23). To this end, a mixed structural resource selection function (mixed-SRSF) approach was used, modelling the probability of finding a lizard on a certain microhabitat based on environmental variables of used and simultaneously available places. First, we controlled for the effects of solar radiation, convection and the physical thermal properties of the substrate on substrate temperature. Then we assessed the effects of solar radiation, convection, conduction and the non-thermal properties of the substrate in the probability of use of a certain microhabi-tat. Results confirmed that substrate temperature was mediated by: air convection > solar radiation > physical thermal properties of the substrates. Moreover, the mixed-SRSF revealed that direct solar radiation and the non-thermal properties of the substrates were the only drivers of microhabitat selection for both species, with approximately the same strength. Our novel approach allowed splitting of the effect of different mechanisms in the microhabitat selection of lizards, which makes it a powerful tool for assessing the conformation of the interactions between different environmental variables mediating animal behaviour.
Terrestrial frogs and toads produce conspicuous vocalizations that may be accompanied by substrate-borne vibrations [1]. Unlike airborne sound, these substrate-borne components are relatively understudied in animal communication. Some anurans exploit the forest floor as a relatively noiseless communication channel in which to propagate call-derived vibrations [2]. Insects on vegetation often use leaves and stems as substrates through which they transmit and receive seismic signals [3]. Here we report that golden rocket frogs calling from their natural substrate generate plant-borne vibrations, and we show that these vibrations can change the frog's behavior. This suggests that plant-borne vibrations can play a role in both modifying the call structure of a vertebrate and directing its movements on the substrate. Many frogs generate substrate vibrations with their airborne calls. Narins et al. show that the vibrational signals from a Guyanese frog's call are sufficient to alter calling behavior and direct movements of neighboring vocalizing frogs. These results suggest that plant-borne vibrations can play an important role in modulating amphibian behavior.
This chapter gives results from some illustrative exploration of the performance of information-theoretic criteria for model selection and methods to quantify precision when there is model selection uncertainty. The methods given in Chapter 4 are illustrated and additional insights are provided based on simulation and real data. Section 5.2 utilizes a chain binomial survival model for some Monte Carlo evaluation of unconditional sampling variance estimation, confidence intervals, and model averaging. For this simulation the generating process is known and can be of relatively high dimension. The generating model and the models used for data analysis in this chain binomial simulation are easy to understand and have no nuisance parameters. We give some comparisons of AIC versus BIC selection and use achieved confidence interval coverage as an integrating metric to judge the success of various approaches to inference.
Male Puerto Rican coqui attract mates by advertisement calling and, once they obtain a clutch, attend eggs at terrestrial nest sites for a 17-26 day period of direct development during which they reduce or cease calling. Most calling sites were open surfaces or shallow depressions lacking close cover, such as the surfaces of leaves and tree trunks, and the axils of sierra palms. Most nest sites were enclosed, protected cavities in dead, curled leaves or rolled sierra palm frond petioles. Calling sites were usually elevated; most nest sites were on the ground. Although ground nests were c3 times more frequent than elevated nests, available substrates on the ground were c16 times more abundant than elevated substrates, suggesting that male coquies preferred elevated substrates. Males using elevated nest sites 1) called more often and from perches closer to their nests, 2) had a higher frequency of multiple clutches, and 3) realized higher hatching success than males nesting on the ground. Males choosing elevated sites realize higher hatching success without sacrificing the chance to attract additional mates, thus reducing a fitness trade-off between male parental care and mate attraction. -from Author
Carpenter frogs, Rana virgatipes, have a 3 mo breeding season when males are territorial and use vocalizations and wrestling to defend calling sites. Median territory residency was approx. 2 wk. Large males spent a higher percentage of nights in territories than small males. Nearest-neighbor analyses indicated that males tended to establish territories close to other calling males. Male switching to new territories was usually associated with aggressive interactions at their old sites, intrusion on other residents, or movements to sites with higher densities of calling males. Calling sites had more submerged shrubs than control sites and were independent of water depth. There were two major types of aggressive interactions: exchanges of aggressive calls and physical fights. Seventeen decisive aggressive calling interactions and 19 decisive fights were observed. Territory residents usually won aggressive calling interactions regardless of intruder size. In contrast, size was more important than residency in determining the outcome of fights. Satellite males were occasionally observed and usually were smaller than residents. Satellite behavior was adopted by either losers of aggressive interactions or small males that may have had difficulty establishing territories. Fifteen matings were observed; mating success was positively correlated with body size and number of nights of calling activity.
Local niche-based processes and dispersal are important determinants of assemblage composition and species diversity. However, there is no consensus about the relative importance of niche and spatial processes to explain the distribution of anuran species in tropical systems. In our study, we analyzed the niche and neutral effects on anuran assemblages and found that biotic interactions were a predictor of assemblage structure. The Eltonian concept of niche was the best predictor for the structure of aquatic-breeding anuran assemblages, as species tended to co-occur more often than would be expected by chance. We suggest that the lack of environmental effect could be explained by differences in the pattern of movement between arboreal and non-arboreal anurans. Once there is a reduction in the number of arboreal anurans in open areas, the importance of habitat heterogeneity to explain assemblage composition should decrease. The lack of correlation between the spatial component in our model and species composition is evidence that spatial processes, such as migration, did not play a major role in structuring local assemblages. Anurans are generally assumed as having poor dispersal ability, yet this assumption is not true for all anuran species. We suggest that future studies should include key behavioral traits, such as site fidelity and homing behavior, as these traits can represent the dispersal abilities of anurans and dispersal ability seems to be important when we try to predict patterns of anuran distribution.
Female painted reed frogs, Hyperolius marmoratus, were subjected to two-choide discrimination experiments to determine whether temporal overlap in the presented stimuli affects frequency preferences. The results showed that females preferred low frequency calls when the stimuli were presented alternately. Simultaneous presentation of stimuli resulted in a random response by females. When presented stimuli partially overlapped or abutted each other, the females responded significantly more often to the leading call irrespective of its frequency. These findings provide some insight into the possible effects of male vocal interactions on the ability of females actively to choose mates based on call frequency in natural breeding assemblages.
Differences among wetlands can have important consequences on reproductive success of amphibians; therefore habitat selection is expected to be of particular importance for anurans inhabiting heterogeneous environments. To investigate if the red-belly toad (Melanophryniscus stelzneri; Anura: Bufonidae) uses available habitats differentially and to determine the main factors influencing the use of certain water bodies as breeding habitat, we surveyed 30 spawning sites used by red-belly toads, and 30 adjacent unused sites, in an area of the Sierras of Córdoba, Argentina. We evaluated the relative importance of morphological and biotic features of ponds, and the presence of other organisms within the water body on the use of ponds as breeding sites by red-belly toads. Eight habitat variables related to important water body features were recorded and were used to fit a habitat selection model with GLM. Red-belly toads presented a positive selection to mallines, a wetland characteristic of the Sierras of Córdoba. They were associated with small, shallow ephemeral ponds with muddy banks and a high percent of vegetation cover. In general, the ponds used did not host other anuran species or potential predators. Breeding site selection by red-belly toads is largely consistent with records for other species of the genus in other parts of Argentina.
The most commonly heard vocalizations of frogs are advertisement calls, which attract gravid females and mediate aggressive interactions between males. Frog vocalizations are energetically costly to produce, and body size often constrains the dominant frequency and intensity of vocalizations; propagation and degradation of these signals are affected by diverse physical and biotic factors. Behaviors and auditory mechanisms that mitigate these problems are discussed. With some exceptions, female preferences based on dominant frequency are intensity-dependent and mediate stabilizing selection within populations. Female preferences based on dynamic, gross-temporal properties typically mediate strong directional selection. The high values of these properties preferred by females increase a male's detectability in dense choruses and are a reliable predictor of his energetic investment in courtship. Female preferences based on fine-temporal properties (e.g. pulse rate) are often in tensity-independent and usually mediate stabilizing selection within populations. The overall attractiveness of a signal depends on variation in more than one of these acoustic properties; their relative importance differs between species. Parsimony analysis supports the idea that auditory biases preceded the evolutionary appearance of call elements that enhance the attractiveness of advertisement calls in one species group of neotropical frogs. A more specific claim that the bias has not been modified by selection after the establishment of the new signal has little empirical support. Indeed, the selective consequences of positive phonotaxis to any ''new'' stimulus, whether or not there is a sensory bias, must play a critical role in its establishment and maintenance as a mate-attraction signal and on the further evolution of the female preference. The hypothesis that present-day selective consequences of mate choice have also acted in the past evolution of call structure and preferences is supported by a few examples of reproductive character displacement. However, evolutionary divergence in signals and preferences will have multiple causes, most of which do not involve interactions between species. Phylogenetic analyses and studies of selection and other evolutionary forces in contemporary populations are complementary approaches to gaining insights about the evolution of frog vocalizations and animal communication in general.
In order to assess the main factors influencing its structure, an anuran community was studied from August 1996 to July 1997, in a 1200 m high rocky meadow site at the Serra do Cipó, Minas Gerais, Brasil, a region with markedly seasonal climate. The study site included three temporary habitats: a stream, a puddle, and a swamp. Thirteen anuran species were recorded at the study site. Species of tadpoles differed in microhabitat as to their position in water column, annual occurrence period, and water flow in the occupied sites. Aquatic vegetation, depth and occupied habitat (stream, swamp, or puddle) were of secondary importance in telling species apart. Calling sites of males were distinguished based on occupied habitat and annual activity period. Most species started their reproductive activities at the onset of the rains, in an opportunistic way. Water availability in the habitat seems to be the most important factor affecting temporal distribution of reproductive activities in the anuran community. Competitive interactions could not be detected in the community. The most important tadpole predators recorded at the study site were belostomatid water bugs and dragonfly nymphs. Their abundance peaks occurred after those of tadpoles, as predicted for predator-prey populations with interconnected cycles. Mortality rates were high for tadpoles, and predation is the most likely cause. Differences recorded among species, considering time of occurrence, tadpole microhabitats, and male calling sites, may reflect distinct specific adaptations and preferences.
Nests and larval development of the nest building gladiator frog, Hyla faber were studied in southeastern Brazil, during the rainy season of 1988-1989. Nests were built at the pond margins, exclusively by males, and varied in shape, size, and composition in relation to the substrate. Nests were used by 1-4 individual males and housed larvae for a mean of 26 days; 0-6 egg clutches were deposited in a nest. Larvae from individual clutches stayed inside the nests for 8-38 days. Embryonic development occurred within the first 210 h after fertilization and larval development, inside an enclosure installed in a pond, lasted over 8 months. Mortality inside the nests was due to nest water evaporation and/or drainage, to eggs sinking in the first hours after fertilization, or to predation by aquatic insects. Slow larval development in Hyla faber seems to be related to breeding in permanent ponds. Nest building in Hyla faber and related species may have evolved from the habit of using natural depressions for egg laying observed in other morphologically similar species.