Ronald Altig

Guilds of Anuran Larvae: Relationships among Developmental Modes, Morphologies, and Habitats

Anurans show a distinct dichotomy among the sources of energy used during larval growth and development, endotrophy and exotrophy. This distinction allows more exact definitions of direct development, ovoviviparity, viviparity, and related terms. Endotrophic larvae, whether as a non-hatched embryo or a free-swimming, non-feeding tadpole, gain immediate developmental nutrition solely from parental sources, most frequently from the yolk allotted to each egg during vitellogenesis. Exotrophic larvae are always free-swimming, feeding tadpoles and orally consume numerous sources of energy not derived from a parent. The morphology of exotrophic tadpoles is surveyed with an emphasis on oral structures. Speculative scenarios and hypotheses concerning the functions of the various morphologies and the relationship of trophic structures to the ecology of the tadpoles are offered. Larval morphology and behavior permit the recognition of six developmental guilds of endotrophic larvae and 18 ecomorphological guilds of exotrophic larvae; these guilds are fully characterized.

Morphological diversity and evolution of egg and clutch structure in amphibians

ABSTRACT The first part of this synthesis summarizes the morphology of the jelly layers surrounding an amphibian ovum. We propose a standard terminology and discuss the evolution of jelly layers. The second part reviews the morphological diversity and arrangement of deposited eggs—the ovipositional mode; we recognize 5 morphological classes including 14 modes. We discuss some of the oviductal, ovipositional, and postovipositional events that contribute to these morphologies. We have incorporated data from taxa from throughout the world but recognize that other types will be discovered that may modify understanding of these modes. Finally, we discuss the evolutionary context of the diversity of clutch structure and present a first estimate of its evolution.

Physical, chemical and biological dynamics of five temporary dystrophic forest pools in Central Mississippi

Five temporary forest pools at Noxubee National WildlifeRefuge,Noxubee Co., Mississippi were surveyed monthly for three yearstogain a better understanding of the dynamics of temporaryaquatichabitats. The objective of this study was to characterize thephysicochemical and biological changes in temporary pools inorderto assess the temporal habitat diversity. These ecosystems,allwithin no more than 4 km of one another, were heterotrophicwith adetrital-based food web derived from allochthonous leaflitter.These pools were chosen because of their close proximity tooneanother, they historically filled and dried seasonally, andtheywere known breeding sites for resident amphibian populations.Only47% of the amphibian cohorts inhabiting the pools appeared tothrive and metamorphose prior to pool desiccation. Successfuldevelopment and dispersal of larvae was variable among poolsandyears. We found that the filling cycles differed amonghabitats andthat physiochemical and biological parameters were highlyvariable.Our data suggest that ephemeral pools in this central piedmontregion of Mississippi are each unique and represent habitatsof lowpredictability for amphibian breeding and success. We concludethatit is erroneous to draw generalizations regarding a ‘typical’temporary pool ecosystem within this region.

Sequence of ontogenetic development and atrophy of the oral apparatus of six anuran tadpoles

The development of the oral structures of six species of anuran tadpoles with four different types of mouth parts and the metamorphic atrophy of these structures in two species with different mouth parts are described. The oral labia of typical tadpoles, oral flaps of microhylids, and lateral oral folds of Rhinophrynus are assumed to be homologous. We also suggest that the barbels of the tadpoles of Rhinophrynus are homologs of the marginal papillae of species with an oral disc. Developmental patterns and sequences of the oral structures of all tadpoles examined follow a common pattern: stomodeal invagination, oral pad development, jaw sheeth delimitation, tooth row ridge development, jaw sheath keratinization, and labial tooth keratinization. Developmental patterns remain constant, while interspecific differences are apparent because of truncations of ontogeny at specific stages. Metamorphic atrophy of oral structures occurs roughly in the reverse order of development, although the procedure is rapid and more haphazard than development.

Occurrence of Oral Deformities in Larval Anurans

Abstract We quantified deformities in the marginal papillae, tooth rows, and jaw sheaths of tadpoles from 13 population samples representing three families and 11 sites in the southeastern United States. Oral deformities were observed in all samples and in 13.5–98% of the specimens per sample. Batrachochytrium dendrobatidis (chytrid) infections were detected in three samples. There was high variability among samples in the pattern and number of discovered deformities. Pairwise associations between oral structures containing deformities were nonrandom for several populations, especially those with B. dendrobatidis infections or high total numbers of deformities. Comparisons of deformities among samples using multivariate analyses revealed that tadpole samples grouped together by family. Analyses of ordination indicated that three variables, the number of deformities, the number of significant associations among deformity types within populations, and whether populations were infected with B. dendrobatidis, were significantly correlated with the pattern of deformities. Our data indicate that the incidence of oral deformities can be high in natural populations and that phylogeny and B. dendrobatidis infection exert a strong influence on the occurrence and type of oral deformities in tadpoles.

Laboratory Behavior of Ascaphus Truei Tadpoles

Laboratory tests of premetamorphic Ascaphus truei tadpoles showed a substrate preference for smooth rocks above 55 mm diameter. The tadpoles were strongly rheotactic and were photonegative in the absence of a current. The tadpoles feed by removing material from the rocks and not by filtering respiratory currents. Passive respiration and feeding do not occur; respiratory currents are caused by undulation of the body wall instead of a gular pump. * * *

Cranial Ontogeny in Siren intermedia (Caudata: Sirenidae): Paedomorphic, Metamorphic, and Novel Patterns of Heterochrony

Cranial development and shape was studied in a large series of the salamander Siren intermedia. Six developmental stages were defined based on timing of ossification and other conspicuous events during ontogeny. Ontogeny of cranial shape was quantified by comparing average landmark configurations describing dorsal cranial shape for each of the six developmental stages by using thin-plate spline and resistant fit theta-rho analyses. Cranial elements in Siren have ontogenetic patterns that are truncated, normal, or completely novel as compared to cranial ontogenies of metamorphosing taxa; overall dorsal cranial shape remains remarkably constant throughout ontogeny. The maxillae, palatopterygoid elements, and hyobranchial apparatus display patterns of heterochrony unique to Siren. The mosaic of larval, metamorphic, and unique patterns of development and cranial-shape paedomorphosis exhibited by Siren fundamentally differs from general patterns of paedomorphosis observed in other taxa. Several of the novel traits seem to be functional adaptations for feeding in the close confines of a burrow.

Descriptions and biological notes on three unusual mantellid tadpoles (Amphibia: Anura: Mantellidae) from southeastern Madagascar

ABSTRACT The morphologies of three unusual tadpoles from slow-flowing, sandy-bottomed, rain forest streams in southeastern Madagascar are described. The large oral apparatus of the tadpole of Boophis picturatus Glaw, Vences, Andreone, and Vallan, 2001 lacks all keratinized structures and has an elaborately-folded lower labium with five, radially oriented, flat-topped ridges. The tadpole of Mantidactylus guttulatus (Boulenger, 1881) lacks all keratinized mouthparts and has three immense papillae where the upper jaw normally occurs. The tadpole of Mantidactylus lugubris (Duméril, 1853) has an ornate oral apparatus involving greatly hypertrophied derivatives of jaw serrations and unique structures on the lower labium that resemble labial teeth.

Two lotic tadpoles from the Andes of southern Peru: Hyla armata and Bufo veraguensis, with notes on the call of Hyla armata (Amphibia: Anura: Hylidae and Bufonidae)

The tadpoles of Hyla armata (Hylidae) and Bufo veraguensis (Bufonidae) from the Amazonian slopes of the Andes in southern Peru and Bolivia are described. These tadpoles, collected from streams draining the Cordillera Oriental in southern Peru, have modifications reflecting adaptations to stream life. These include, in Hyla armata, an enlarged oral disc with numerous labial tooth rows and complete marginal papillae and, in Bufo veraguensis, a belly sucker, unique within the genus but similar to the more fully‐developed sucker of Atelopus tadpoles. In addition, Bufo veraguensis tadpoles are unusual for Bufo in having a dextral vent, high density of labial teeth with no unbroken rows, and small external nares. The morphology of the tadpoles of Hyla armata and Bufo veraguensis is as yet uninformative regarding the relationships to these two unusual frogs. The advertisement call of Hyla armata consists of a single, high‐pitched note with a dominant frequency of 4.7 KHz.

Oral disc muscles of anuran tadpoles

The presence and configurations of the small, extrinsic muscle fibers of the M. mandibulolabialis superior in the upper labium and the M. inferior in the lower labium are described for 24 species in 9 families. Although several species possess only the M. inferior, or both the M. inferior and superior, none has only the M. superior. Some species without tooth rows possess the M. inferior, and microhylid tadpoles have a single‐stranded muscle different than the M. mandibulolabialis in each oral flap. The extrinsic oral muscles insert near the bottom of the inter‐row valleys behind each tooth ridge and the bases of marginal papillae lateral to the ends of tooth rows. Muscles do not extend to marginal papillae beyond the most distal row of teeth. Muscle contraction is presumed to rotate the teeth distally so that they contact the substrate at the proper working angle. This action probably occurs at full extension of the oral disc just before disc closure starts.