Seed predation,disease and germination on landslides in Neotropical lower montane wet forest

Abstract. Seed mortality (caused by predators and pathogens) and germination were compared between Puerto Rico and Costa Rica on landslides in lower montane wet forest. Seeds of six common species on five Puerto Rican landslides and four common species on two Costa Rican landslides were used with a Cecropia species and a Gonzalagunia species included at both sites. In the Puerto Rican experiments Cecropia schreberiana was the only species to show significant seed predation (which was due to insects), pathogens grew from all species and fewer seeds were lost to predators than pathogens. Also in Puerto Rico mean germination across all species was 57 % before dispersal (filled seeds collected while still on the tree) and 71 % after, with Phytolacca rivinoides seeds germinating most abundantly, followed in descending order by Ocotea leucoxylon, Cecropia spec, Miconia racemosa, Palicourea riparia and Gonzalagunia spicata. In the Costa Rican experiments three species had significant predation: Cecropia polyphlebia and Urera caracasana (both due to insects) and Witheringia coccoloboides (due to mammals); pathogenic disease caused more seed loss than predation, and germination was high (61 % pre-dispersal, 69 % post-dispersal). Similarities between these island and mainland sites included (1) percentage of seeds lost to predation and percentage lost to pathogens (all in the 5–15 % range), (2) generalist pathogens which claimed more seeds than predators and (3) majority germination with a general increase after dispersal. Finally sites were dissimilar only in the number of species with significant predation loss and whether it was by insects or mammals, casting doubt on the traditional island/mainland dichotomy.     

Trophic structure of a neotropical frugivore community: is there competition between birds and bats?

Summary Dietary overlap and competition between frugivorous birds and bats in the Neotropics have been presumed to be low, but comparative data have been lacking. We determined the diets of volant frugivores in an early successional patch of Costa Rican wet forest over a one month period. Ordination of the diet matrix by Reciprocal Averaging revealed that birds and bats tend to feed on different sets of fruits and that diets differed more among bat species than among bird species. However, there was overlap between Scarlet-rumped Tanagers and three Carollia bat species on fruits of several Piper species which comprised most of the diet of these bats. Day/night exclosure experiments on P. friedrichsthalli treetlets provided evidence that birds deplete the amount of ripe fruit available to bats. These results indicate that distantly related taxa may overlap in diet and compete for fruit, despite the apparent adaptation of animal-dispersed plant species for dispersal by particular animal taxa.     

To hatch and hatch not: similar selective trade-offs but different responses to egg predators in two closely related, syntopic treefrogs

Risk-sensitive hatching is adaptive for species facing a trade-off between egg-stage and post-hatching risks, and environmental variation in one or both stages. Such plasticity has been found in amphibians, fishes, reptiles and spiders, with red-eyed treefrogs (Agalychnis callidryas) being the best-studied case. We assessed hatching plasticity and egg- and larval-stage risks in a closely related, syntopic species, the gliding leaf-frog (Agalychnis spurrelli). We found a lower hatching response to egg-eating snakes in A. spurrelli (9–28% of embryos escaped) than in A. callidryas (59–80% escaped). Levels of snake predation were similarly high for clutches of both species monitored at a pond in Costa Rica, and in fish predation experiments early-hatched A. spurrelli tadpoles were more vulnerable than later hatchlings, as has been shown for A. callidryas. A. spurrelli thus face a risk trade-off similar to A. callidryas, and likely would benefit from predator-induced hatching; their lower responsiveness to snakes appears nonadaptive. A. spurrelli embryos showed a stronger hatching response (57% hatched in 1 h) to submergence underwater than to snake attacks even though submergence is a less frequent risk. This suggests they have a greater capacity for early hatching than is expressed in the context of snake attacks, but have much lower sensitivity to snake cues than to flooding cues. Development in A. spurrelli is accelerated compared to syntopic A. callidryas, and spontaneous hatching is earlier and more synchronous. This is congruent with predictions based on selection by egg predators in the absence of a strong escape hatching response.     

Genetic and phenotypic variation in a colourful treefrog across five geographic barriers

Aim Understanding the patterns and processes underlying phenotype in a polytypic species provides key insights into microevolutionary mechanisms of diversification. The red‐eyed treefrog, Agalychnis callidryas, exhibits strong regional differentiation in colour pattern, corresponding to five admixed mitochondrial DNA clades. We evaluated spatial diversity patterns across multiple, putative barriers to examine the fine‐scale processes that mediate phenotypic divergence between some regions while maintaining homogeneity between others. Location We examined patterns of phenotypic diversification among 17 sites that span five putative biogeographic barriers in lower Central America (Costa Rica and Panama). Methods We tested the extent to which genetic distance (F_ST) derived from six multilocus nuclear genotypes covaried with measures of phenotypic distance (leg coloration) within and between biogeographic regions. We used linear regression analyses to determine the role of geographic and genetic factors in structuring spatial patterns of phenotypic diversity. Results The factors that best explained patterns of phenotypic diversity varied among biogeographic regions. We identified one geographic barrier that impeded gene exchange and resulted in concordant phenotypic divergence across the Continental Divide, isolating Caribbean and Pacific populations. Across Caribbean Costa Rican populations, one barrier structured phenotypic but not genetic diversity patterns, indicating a role for selection. In other regions, the putative barriers had no determining effect on either genetic or leg colour structure. Main conclusions The processes mediating the distribution and diversification of colour pattern in this polytypic, wide‐ranging treefrog varied among biogeographic regions. Spatially varying selection combined with the isolating effects of geographic factors probably resulted in the patchy distribution of colour diversity across Costa Rican and Panamanian populations.     

The hyolaryngeal apparatus of three species of Scinax (Scinaxinae: Hylidae: Anura) and comparison with other Hylidae species

The hyolaryngeal apparatus includes the arytenoid, cricoid and hyoid cartilages, and varied sizes and shapes can be distinguished between species. Although the larynx is an important morphological structure for sound production in frogs, few studies describe the structures and processes of its parts in hylids. We studied the hyolaryngeal anatomy of both males and females of Scinax ruber (Laurenti, 1768), using clearing and double staining methods, comparing it with that of Scinax wandae (Pyburn and Fouquette, 1971), Scinax kennedyi (Pyburn, 1973) and other hylid species. We found that S. ruber has the largest arytenoid cartilage of any species of the subfamily Scinaxinae studied to date. We described both the laryngeal differences among three Scinax species and the interspecific variability in the shapes of the projections of the arytenoid in the males of these species. The taxonomic characters (presence/absence of processes of the cartilage of Santorini, oesophageal process or bronchial processes) described here can play a key role in differentiating these species from Scinax species and from other species. In addition, we want to contribute to the natural history and comparison of the larynges in Scinax and within the genus and the Hylidae.     

Interactions Between Competition and Predation Shape Early Growth and Survival of Two Neotropical Hylid Tadpoles

Experimental studies in temperate regions have revealed that competition and predation interact to shape aquatic communities. Predators typically reduce the effect of competition on growth and competitors provide alternative prey subjects, which may also alter predation. Here, we examine the independent and combined effects of competition and predation on the survival and growth of hatchling tadpoles of two widespread co‐occurring Neotropical hylid frogs (Agalychnis callidryas and Dendropsophus ebraccatus). Using 400 L mesocosms, we used a 2 × 3 factorial substitutive design, which crossed tadpole species composition with the presence or absence of a free‐roaming predator (Anax amazili dragonfly larva). Dragonflies were effective predators of both species, but had larger effects on A. callidryas survival. Both species had similar growth rates when alone, whereas A. callidryas grew 30 percent faster than D. ebraccatus when they co‐occurred, suggesting interspecific rather than intraspecific competition had relatively stronger effects on D. ebraccatus growth, while the opposite was true for A. callidryas. Predator presence dramatically reduced growth rates of both species and erased this asymmetry. Results suggest that the effects of predator induction (i.e., nonconsumptive effects) on growth were larger than both consumptive and competitive effects. Our study demonstrates that predators have strong effects on both survival and growth of prey, highlighting the potential importance of predators in shaping prey populations and tropical aquatic food web interactions. Abstract in Spanish is available at http://www.blackwell‐synergy.com/loi/btp .     

A synopsis of Costa Rican Ruellia (Acanthaceae), with descriptions of four new species

We describe four new species of Ruellia from Costa Rica; three from the Osa Peninsula, Puntarenas province (R. exilis, R. mira, R. odorata), and one from the southwestern corner of San José province (R. norvegigratiosa). Ruellia matagalpae is reported as a new record for the country. New combinations are made in Ruellia for the two Costa Rican species of Blechum (R. blechum and R. costaricensis). Three species are reduced to synonymy, and another species is considered doubtfully worthy of recognition. Notable range extensions are reported for two species. Corollas and fruits of all 22 Costa Rican species of Ruellia are shown and compared as easily used identification aids. An informal guide to species groups and a dichotomous key to the 22 species are presented.     

Biomass allocation,growth, and photosynthesis of genotypes from native and introduced ranges of the tropical shrub<Emphasis Type="Italic"> Clidemia hirta</Emphasis>

We tested the hypothesis that the tropical shrub Clidemia hirta appears more shade tolerant and is more abundant in its introduced than native range because of genetic differences in resource acquisition, allocation, and phenotypic plasticity between native and introduced genotypes. We examined growth, biomass allocation, and photosynthetic parameters of C. hirta grown in a greenhouse from seed collected from four populations in part of its native range (Costa Rica) and four populations in part of its introduced range (Hawaiian Islands). Six-month-old seedlings were placed in high (10.3–13.9 mol m^–2 day^–1) or low (1.4–4.5 mol m^–2 day^–1) light treatments and grown for an additional 6 months. Our study provided little evidence that Hawaiian genotypes of C. hirta differed genetically from Costa Rican genotypes in ways that would contribute to differences in habitat distribution or abundance. Some of the genetic differences that were apparent, such as greater allocation to stems and leaf area relative to whole plant biomass in Costa Rican genotypes and greater allocation to roots in Hawaiian genotypes, were contrary to predictions that genotypes from the introduced range would allocate more biomass to growth and less to storage than those from the native range. Hawaiian and Costa Rican genotypes displayed no significant differences in relative growth rates, maximal photosynthetic rates, or specific leaf areas in either light treatment. In the high light environment, however, Hawaiian genotypes allocated more biomass to reproductive parts than Costa Rican genotypes. Phenotypic plasticity for only 1 of 12 morphological and photosynthetic variables was greater for Hawaiian than Costa Rican genotypes. We conclude that genetic shifts in resource use, resource allocation, or plasticity do not contribute to differences in habitat distribution and abundance between the native and introduced ranges of C. hirta. Electronic Supplementary Material Supplementary material is available in the online version of this article at . Clidemia hirta individuals grown in a common garden in high light for 10 months from Hawaiian (left) or Costa Rica (right) seed sources     

A new eutardigrade from Costa Rica with taxonomical and zoogeographical remarks on Costa Rican tardigrades

In a moss sample collected in Costa Rica, 63 specimens and 13 eggs of the new species were found. Mesobiotus pseudopatiens sp. nov. belongs to the harmsworthi group and is most similar to Mesobiotus patiens, but it differs from it mainly by smaller eggs, longer flexible portions of egg processes and certain morphometric characters of adults. In addition, after re-examination of specimens of the genus Milnesium collected in Costa Rica, a new record of Milnesium kogui may be added to Costa Rican fauna. The paper also discusses taxonomical problems and the zoogeography of Costa Rican tardigrades, which partially agree with hypotheses of Great American Biotic Interchange and Mexican Transition Zone. A large number of so-called ‘Costa Rican species’ are doubtful taxa with ‘cosmopolitan’ distribution; the largest number of species, however, have tropical/subtropical or neotropical distribution. Certain species from colder regions are also present in the mountains of Costa Rica.

http://zoobank.org/urn:lsid:zoobank.org:pub:F6F6195E-0888-4279-A3AF-422642F8B40     

Ex situ Diet Influences the Bacterial Community Associated with the Skin of Red-Eyed Tree Frogs (Agalychnis callidryas)

Amphibians support symbiotic bacterial communities on their skin that protect against a range of infectious pathogens, including the amphibian chytrid fungus. The conditions under which amphibians are maintained in captivity (e.g. diet, substrate, enrichment) in ex situ conservation programmes may affect the composition of the bacterial community. In addition, ex situ amphibian populations may support different bacterial communities in comparison to in situ populations of the same species. This could have implications for the suitability of populations intended for reintroduction, as well as the success of probiotic bacterial inoculations intended to provide amphibians with a bacterial community that resists invasion by the chytrid fungus. We aimed to investigate the effect of a carotenoid-enriched diet on the culturable bacterial community associated with captive red-eyed tree frogs (Agalychnis callidryas) and make comparisons to bacteria isolated from a wild population from the Chiquibul Rainforest in Belize. We successfully showed carotenoid availability influences the overall community composition, species richness and abundance of the bacterial community associated with the skin of captive frogs, with A. callidryas fed a carotenoid-enriched diet supporting a greater species richness and abundance of bacteria than those fed a carotenoid-free diet. Our results suggest that availability of carotenoids in the diet of captive frogs is likely to be beneficial for the bacterial community associated with the skin. We also found wild A. callidryas hosted more than double the number of different bacterial species than captive frogs with very little commonality between species. This suggests frogs in captivity may support a reduced and diverged bacterial community in comparison to wild populations of the same species, which could have particular relevance for ex situ conservation projects.     

Three new species in the neotropical genus <Emphasis Type="Italic">Clidemia</Emphasis> (Melastomataceae: Miconieae)

We here propose and describe three new species of Clidemia: C. aguilarii from Costa Rica and Panama; C. aurantiaca from Costa Rica, Panama, and Ecuador; and C. subpeltata, a Costa Rican endemic. Phenological notes, distribution maps, line drawings, color images of the live plants in the wild, and discussions comparing the new species to their presumed closest relatives are provided.     

Parasite loss and introduced species: a comparison of the parasites of the Puerto Rican tree frog, (<Emphasis Type="Italic">Eleutherodactylus coqui</Emphasis>), in its native and introduced ranges

The Puerto Rican frog, Eleutherodactylus coqui has invaded Hawaii and reached densities far exceeding those in their native range. One possible explanation for the success of E. coqui in its introduced range is that it lost its co-evolved parasites in the process of the invasion. We compared the parasites of E. coqui in its native versus introduced range. We collected parasite data on 160 individual coqui frogs collected during January-April 2006 from eight populations in Puerto Rico and Hawaii. Puerto Rican coqui frogs had higher species richness of parasites than Hawaiian coqui frogs. Parasite prevalence and intensity were significantly higher in Hawaii, however this was likely a product of the life history of the dominant parasite and its minimal harm to the host. This suggests that the scarcity of parasites may be a factor contributing to the success of Eleutherodactylus coqui in Hawaii.     

Acoustic,auditory, and morphological divergence in three species of neotropical frog

Advertisement calls, auditory tuning, and larynx and ear morphology were examined in 3 neotropical frogs, Hyla microcephala, H. phlebodes and H. ebraccata, H. microcephala has the highest call dominant frequency (6.068 kHz) and basilar papilla tuning (5.36 kHz). H. phlebodes and H. ebraccata calls have lower dominant frequencies (3.832 and 3.197 kHz respectively) and basilar papilla tuning (2.79 and 2.56 kHz). The primary call notes of H. ebraccata are longer (181.6 ms) than those of H. microcephala (95.5 ms) or H. phlebodes (87.3 ms). Morphometric analysis suggests that temporal call features differ as laryngeal musculature changes, in the process changing the overall size of the larynx. The spectral aspects of the call differ as head size, and hence the size of its resonating and radiating structures, changes, modifying the dominant frequency of calls by accentuating their higher harmonics when head size decreases. Decreasing head size decreases the size of the middle and inner ear chambers, changing the mechanical tuning of the ear in the same direction as the change in dominant frequency. These changes result in divergent spectral-temporal characteristics of both the sending and receiving portions of the acoustic communication system underlying social behavior in these frogs.Abbreviations AP amphibian papilla - BEF best excitatory frequency - BP basilar papilla - dB SPL decibels sound pressure level re:20 N/m²     

Effects of shrub encroachment on the anuran community in periodically flooded grasslands of the largest Neotropical wetland

In many parts of the world, replacement of natural grasslands by woody plants has resulted in a decrease of pasture areas and in habitat loss for a variety of animal species, including amphibians. Wetlands are especially susceptible to invasive plants, both native and exotic, but the effects of such invasions on animal assemblages remain poorly understood. Here, we present information on the impact of selected environmental variables, especially coverage by the native shrub Combretum laxum Jacq., on the structure of an anuran assemblage in the Pantanal, a huge flood‐pulsed South American wetland. Anurans were surveyed during the rainy season in 17 plots, which differed in extent of C. laxum coverage, leaf litter volume, soil moisture and distance to permanently wet areas. Effects of these environmental variables on the species number, relative abundance and composition of the anuran assemblage were evaluated using multivariate statistical analyses. We captured 1203 anurans, of 21 species from four families. Both the number of species and the relative abundance of anurans were lower in plots with greater C. laxum coverage, which also influenced anuran species composition. Number of species was highest in plots located closest to permanently wet areas, which provide protection from desiccation and other resources during the Pantanal dry season, and so could be considered source areas of anurans. While many anuran species were negatively affected by the homogenization of the landscape caused by shrub encroachment, some seemed to be favoured in such circumstances. For these, dense shrub encroachment into natural grasslands may provide safer migratory routes to permanently wet habitats. Thus, at the mesoscale, a mosaic of areas with different levels of coverage by C. laxum (shrub islands) may aid anuran assemblages in the Pantanal wetlands, facilitating the maintenance of higher beta and gamma diversity.     

A new species of small-eared shrew in the <Emphasis Type="Italic">Cryptotis thomasi</Emphasis> species group from Costa Rica (Mammalia: Eulipotyphla: Soricidae)

We describe a new species of small-eared shrew, genus Cryptotis Pomel, 1848 (Eulipotyphla: Soricidae), from near the community of Monteverde in the Tilarán highlands of northwestern Costa Rica. The new species is immediately distinguished from all other Costa Rican shrews its large size and long tail. Morphologically, it belongs to the Cryptotis thomasi group of small-eared shrews, a clade that is more typically distributed in the Andes Cordillera and other highland regions of northern South America. The new Costa Rican species and the Panamanian endemic Cryptotis endersi Setzer, 1950 are the only two members of this species group known to occur in Central America. Like most other members of the C. thomasi group for which the postcranial skeleton has been studied, the new species tends be more ambulatory (rather than semi-fossorial) when compared with other members of the genus. Our survey efforts over several decades failed to locate a population of the new species, and we discuss its conservation status in light of its limited potential distribution in the Tilarán highlands and the significant climatic change that has been documented in the Monteverde region during the past four decades.     

<Emphasis Type="Italic">In vitro</Emphasis> fertilization and artificial activation of eggs of the direct-developing anuran <Emphasis Type="Italic">Eleutherodactylus coqui</Emphasis>

Although much is known about the reproductive biology of pond-breeding frogs, there is comparatively little information about terrestrial-breeding anurans, a highly successful and diverse group. This study investigates the activation and in vitro fertilization of eggs of the Puerto Rican coqui frog obtained by hormonally induced ovulation. We report that spontaneous activation occurs in 34% of eggs, probably in response to mechanical stress during oviposition. Artificial activation, as evidenced by the slow block to polyspermy and the onset of zygote division, was elicited both by mechanical stimulation and calcium ionophore exposure in 64% and 83% of the cases, respectively. Finally, one in vitro fertilization protocol showed a 27% success rate, despite the fact that about one third of all unfertilized eggs obtained by hormone injection auto-activate. We expect these findings to aid in the conservation effort of Eleutherodactylus frogs, the largest vertebrate genus.     

Lateralized Turning Biases in Two Neotropical Tadpoles

Lateralized turning behavior in startle responses and upon descent after surfacing for a breath of air has been documented for tadpoles in several anuran species. A left‐handed preference is most common and was previously thought to be linked to the asymmetry in spiracle location. Here, we investigate the presence of behavioral asymmetries in tadpoles of Agalychnis callidryas and Leptodactylus melanonotus in explosive turns after air‐breathing. Data were also collected on lateralized posture in the orientation of tails of embryonic A. callidryas within the egg case, as well as the startle response of free‐swimming tadpoles exposed to mechanical stimulation. A left‐curled tail bias was found among several clutches from Costa Rica, but this was not the case among clutches examined from Panama. Free‐living tadpoles of L. melanonotus displayed a distinct right‐handed preference during explosive turns. While some tadpoles of A. callidryas were at stages too early to detect any explosive turns when breathing, later‐staged individuals did display a left‐handed bias in startle response to mechanical stimulation. Additionally, it appears that the expression of behavioral lateralization of larvae (but not embryos) may predict whether or not the adults exhibit similar lateralization. Findings herein provide insight into the ontogeny and evolutionary origins of lateralized behavior in anurans.     

Prevalence of endoparasitic mites on four West African leaf‐litter frogs depends on habitat humidity

Amphibian species are known to carry endoparasitic mites. The infestation probability, prevalence, and intensity of mites vary among species and habitats. Mites of the genus Endotrombicula are known to infest African and Malagasy frogs. However, the factors leading to an increase in the probability of mite infestation are unknown. To test for inter‐ and intraspecific differences in infestation probability and its potential correlation with sex, age, habitat preferences, and/or season within a species‐rich West African leaf‐litter frog assemblage, we examined more than 6,800 individual frogs for the presence of mites throughout two independent time increments, 1999–2000 and 2016–2017. We found only members of the leaf‐litter frog genus Phyrnobatrachus to be infested, while other syntopically occurring genera were not affected. Within Phrynobatrachus, only four out of eight species were infested. Mites prevalence differed between species (highest P. phyllophilus, followed by P. alleni), sex (males higher than females in P. alleni and P. phyllophilus), and age (adults higher than juveniles in P. alleni), as well as season (more mites during wet than dry season in P. phyllophilus). The prevalence of mite infestation did not influence mate choice in P. alleni. Increased humidity showed a clear positive effect on infestation prevalence. We also detected a marked decrease in the prevalence of mites from 1999–2000 to 2016–2017, a period during which climatological changes within the study area have been reported with a tendency toward drier conditions. The decrease in mite infestation prevalence over time might be a signal of increasingly drier conditions.     

The freshwater Copepoda (Crustacea) of Costa Rica with notes on some species

Sixteen species of Copepoda were recorded in this first detailed study of Costa Rican zooplankton. Two of these species are halophile. Notes are given on some of the species and their distribution. One new species found will be described elsewhere. The Costa Rican fauna resembles in composition the fauna of other Central American and Caribbean regions. Relatively few species were recorded. This is partly due to a low intensity of sampling but also to the paucity of lentic habitats. The occurrence of two circumtropical species of Mesocyclops is interesting.

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Résumé 16 espèces de Copépodes ont été inventoriées au cours d'une première étude détaillée du zooplankton dulcaquicole de Costa Rica. Deux des espèces trouvées sont halophiles. Des remarques sont faites a propos de quelques espèces et de leur répartition. Une nouvelle espèce est nouvelle — elle sera décrite par ailleurs. La fauna de Costa Rica ressemble par sa composition à celle des autres pays d'Amérique centrale et des îles caraibes. Relativement peu d'espèces sont notées. La faible intensité de l'échantillonnage mais aussi la pauvreté en habitats limniques en sont responsables. La présence de deux espèces circumtropicales de Mesocyclops est intéressante.

     

Geographic Variation in Male Sexual Signals in Strawberry Poison Frogs (Dendrobates pumilio)

In this paper, we compare the advertisement calls of 207 neotropical strawberry poison frogs (Dendrobates pumilio) collected in 21 localities along a transect from northern Costa Rica to western Panama. Populations varied most in call duration and call rate, while pulse rate and duty cycle were less variable. Multivariate analyses showed that call variation followed a cline with higher call rates, shorter calls, lower duty cycles and higher pulse rates in the southeast. Body size decreased towards the southeast and explained most variation in dominant frequency, as well as some residual variation in call rate. We conclude that a combination of geography and morphology is largely responsible for call variation within this species. Two inferred bio‐acoustic groups were roughly in accordance with two genetic groups, geographically separated in central Costa Rica. However, genetic distances among populations did not co‐vary with call dissimilarity after correction for geographic distances. Thus, differences in calls between genetic groups are probably mainly a result of clinal variation. These findings agree with the general observation that bio‐acoustic variation is often not (highly) associated with genetic divergence. Moreover, colour polymorphism observed among Panamanian populations was not reflected in a higher variability in call parameters relative to the monomorphic Costa Rican populations.