Toe Tip Morphology in Six Species of Salamanders, genus Ambystoma (Caudata: Ambystomatidae) from Arkansas Using Scanning Electron Microscopy

The toe tip friction surface in six species of Ambystoma (A. annulatum, A.maculatum, A.opacum, A. talpoideum, A. texanum, and A. tigrinum) from Arkansas was examined using scanning electron microscopy. We found no sexual dimorphism in cell surface ultrastructure. Variation within and between species was considerable. The most active burrower, A. tigrinum, possessed the most disorganized cell surface, whereas the least active burrowers (A.annulatum, A.maculatum, and A. opacum) had morphologically similar and relatively smooth toe tips. In A. talpoideum and A. texanum, cell surfaces exhibited microprojections. Only these two species possessed mucous pores in close proximity to the friction surface. The microstructure of cell surfaces transcended species groups in Ambystoma and would not represent a reliable taxonomic tool

Ambystoma macrodactylum

Number of Pages: 2Place of Publication: Bethesda, MarylandIntegrative BiologyGeological Science

Co-Cultures of Oophila Amblystomatis Between Ambystoma Maculatum and Ambystoma Gracile Hosts Show Host-Symbiont Fidelity

A unique symbiosis occurs between embryos of the spotted salamander (Ambystoma maculatum) and a green alga (Oophila amblystomatis). Unlike most vertebrate host-symbiont relationships, which are ectosymbiotic, A. maculatum exhibits both an ecto- and an endo-symbiosis, where some of the green algal cells living inside egg capsules enter embryonic tissues as well as individual salamander cells. Past research has consistently categorized this symbiosis as a mutualism, making this the first example of a “beneficial” microbe entering vertebrate cells. Another closely related species of salamander, Ambystoma gracile, also harbors beneficial Oophila algae in its egg capsules. However, our sampling within the A. gracile range consistently shows this to be a strict ectosymbiotic interaction—with no sign of tissue or presumably cellular entry. In this study we swapped cultured algae derived from intracapsular fluid of different salamander hosts to test the fidelity of tissue entry in these symbioses. Both A. maculatum and A. gracile embryos were raised in cultures with their own algae or algae cultured from the other host. Under these in vitro culture conditions A. maculatum algae will enter embryonic A. maculatum tissues. Additionally, although at a much lower frequency, A. gracile derived algae will also enter A. maculatum host tissues. However, neither Oophila strain enters A. gracile hosts in these co-culture conditions. These data reveal a potential host-symbiont fidelity that allows the unique endosymbiosis to occur in A. maculatum, but not in A. gracile. However, preliminary trials in our study found that persistent endogenous A. maculatum algae, as opposed to the cultured algae used in subsequent trials, enters host tissues at a higher frequency. An analysis of previously published Oophila transcriptomes revealed dramatic differences in gene expression between cultured and intracapsular Oophila. These include a suite of genes in protein and cell wall synthesis, photosynthesis, central carbon metabolism suggesting the intracapsular algae are assimilating ammonia for nitrogen metabolism and may be undergoing a life-cycle transition. Further refinements of these co-culture conditions could help determine physiological differences between cultured and endogenous algae, as well as rate-limiting cues provided for the alga by the salamander

UPDATED GEOGRAPHIC DISTRIBUTIONS OF MICHIGAN HERPETOFAUNA:: A SYNTHESIS OF OLD AND NEW SOURCES

Recently a comprehensive overview of reptiles and amphibians in Michigan was published. Unfortunately, the distributions of the species represented were compiled before widespread accessibility to technological tools providing greater access to museum and historical records as well as citizen science efforts. To update the known ranges of Michigan herpetofauna, published literature, museum collections, and photographic vouchers submitted to an online database were examined and 339 new county and island records were added, updating the maps for 48 of Michigan’s 55 known species of reptiles and amphibians. I also present the first published list of Michigan amphibians that includes two new plethodontid salamanders, the Northern Dusky Salamander (Desmognathus fuscus) and Southern Two-lined Salamander (Eurycea cirrigera). This paper serves as an example of the wealth of information available to scientists that may have previously been unobtainable, and can be used for the distribution of herpetofauna elsewhere

Ambystoma gracile

Number of Pages: 2Place of Publication: Bethesda, MarylandIntegrative BiologyGeological Science

Ambystoma mabeei

Number of Pages: 2Integrative BiologyGeological Science

THE ART OF WAR: PATTERNS AND MECHANISMS UNDERLYING PREDATOR-INDUCED PLASTICITY OF AMPHIBIANS

Organisms often employ phenotypic plasticity as a strategy to cope with variable environments. This is particularly true of predation threats, wherein prey induce defenses to reduce detection or capture by predators. In order to produce appropriate defenses, prey must be able to discern useful information from environmental cues. Despite the pervasive production of inducible defenses, we understand very little of how much useful information is conveyed to organisms in cues, or how the subsequent plastic responses vary within groups of organisms. To address the need for comparative studies of phenotypic plasticity, we sought to examine morphological and behavioral defenses of five species of Ambystoma salamander larvae in response to larval dragonfly (Anax junius) chemical cues in a common garden environment. Dragonfly cues induced relatively few morphological changes across species. Likewise, salamanders did not vary in their refuge use during the experiment, though several species reduced their activity in the presence of predators early in development. Our results suggest that behavioral and morphological defenses in Ambystoma are highly variable among species and the genus appears to be less plastic than tadpoles and other salamander species. To understand what types of information prey are capable of responding to in their environment, we raised grey treefrog tadpoles (Hyla verisciolor) in the presence of cues isolated from different stages of an attack sequence by larval dragonflies (A. junius) or larval dragonflies THE ART OF WAR: PATTERNS AND MECHANISMS UNDERLYING PREDATOR-INDUCED PLASTICITY OF AMPHIBIANS Heather Michelle Shaffery, M.S. University of Pittsburgh, 2013 iv consuming different combinations of grey treefrog tadpoles and snails (Helisoma trivolvis) across different temporal sequences. When exposed to a predator consuming grey treefrogs, tadpoles reduced their activity, increased their hiding behavior, and induced deeper tails. As we exposed prey to more types of cues from an attack sequence, they also increased tail depth and hiding behavior but did not change their activity. Additionally, treefrog tadpoles generally increased their defense as the biomass of treefrogs consumed increased, regardless of whether heterospecifics were being consumed. Our results suggest that treefrogs can gain cue information from all portions of an attack sequence, and that both temporal patterns of feeding and diet content of predators influence the type and magnitude of induced prey defenses