I rather study frogs using a multidisciplinary approach instead of concentrating in a single field. During my Masters I worked on describing frog sperm ultrastructure and on the relationships of these cell's morphology to phylogeny and reproductive biology. I have also worked with lizard taxonomy and descriptive ecology of reptiles and amphibians.

On my Ph.D. dissertation I am working on phylogeny, biogeography, and population genetics of a group of nine species of frogs, commonly known as the paradoxical frogs.

1. Frog Anatomy
2. Frog and Lizard Ecology
3. Frog Phylogeny and Biogeography
4. Taxonomy

Sperm Ultrastructure

Spermatozoon ultrastructure has been used as an alternative data set to investigate phylogenies of many taxa such as fishes (Jamieson, 1991), amphibians (Scheltinga et al., 2001; Garda et al., 2002), reptiles (Teixeira et al., 1999), and several invertebrates (Jamieson & Rouse, 1989).

Sperm ultrastructure data can provide more conservative characters for groups with highly derived body plans, such as Amphisbaenia (Teixeira et al., 1999). Among amphibians, which are also morphologically conserved, submicroscopic anatomy and soft tissue anatomy have recently shed light on several taxonomic problems (Costa et al., 2004).

During my masters thesis, I worked on describing sperm ultrastructure of three previously underscribed families: Dendrobatidae, Microhylidae, and Pseudidae (now nested within Hylinae). Along with morphological descriptions based on electron microscopy micrographs, we tried to make sense of the observed structures, on a functional and phylogenetic context.

In Pseudis and Lysapsus, for example, sperm cells are very simplifyed, as is common for several species with free swimming sperm (Aquasperm, sensu Rouse & Jamieson, 1987). According to Jamieson & Rouse (1991), aquatic free-swimming sperm cells are prone to structure reduction. This is also the case for Pseudininae, where several complex structures present in bufonoid sperm are missing (compare Figures 1 and 2).

Other cases of such simplification led Jamieson et al. (1993) to suggest that sperm ultrastructure was correlated to fertilization environment in anurans. However, when applying a phylogeny-based comparative method to the mostly accepted phylogeny of anurans, Garda et al. (2004) found that the hypothesis is, at best, equivocal.

 These are not, however, definite answers. Sperm ultrastructure of many species await description, and variation within each taxonomic group must be assessed before general conclusions are attained. Several examples indicate that such characters are very useful for genera characterization (Garda et al., 2004; Costa et al., 2005).

Ongoing Research

Currently I am working in collaboration with Dr. Sônia Báo, Guarino Colli, and Shélida Braz to finish describing Pseudis and Lysapsus sperm ultrastructure . Since sperm ultrastructure characters are the only ones currently separating the two genera (Faivoich et al., 2005), mapping the character evolution onto a phylogeny of Pseudini will be insightful about sperm ultrastructure character evolution.

Soft Anatomy

In a second collaboration I am working with Antonio Sebben, at the Comparative Anatomy laboratory at the university or Brasília (UnB). Together with his undergraduate student, Patrícia Wanderley, we are exploring Pseudinae soft anatomy in order to find characters for phylogenetic reconstruction. Currently, Patrícia is working on mesenteric vascularization in Pseudis. Blood mesenteric irrigation is highly reduced in Pseudinae frogs, but differences among species are also observed.

Osteology of Pseudis and Lysapsus

In a third collaboration work, I am currently compleating a matrix started by Monica Barg on her dissertation on the osteology of Pseudis. We are working together to built a osteological phylogeny of Pseudis and Lysapsus.

Bibliography

Costa GC, Vieira GHC, Teixeira RD, Garda AA, Colli GR, Báo SN, 2004. An ultrastructural comparative study of the sperm of Hyla pseudopseudis, Scinax rostratus, and S. squalirostris (Amphibia: Anura: Hylidae). Zoomorphology, 123:191-197. Download PDF.

Garda AA, GR Colli, O Aguiar-Junior, SM Recco-Pimentel, & SN Báo. 2002. The ultrastructure of the spermatozoa of Epipedobates flavopictus (Amphibia, Anura, Dendrobatidae), with comments on its evolutionary significance. Tissue&Cell 34:356-364. Download PDF.

Garda AA, Costa GC, Colli GR, & Báo SN. 2004. Spermatozoa of Pseudinae (Amphibia, Anura, Hylidae), with a test of the hypothesis that sperm ultrastructure correlates with reproductive modes in anurans. Journal of Morphology, 261: 196-205. Download PDF.

Jamieson BGM, GW Rouse. 1989. The spermatozoa of Polychaeta (Annelida) – An ultrastructural review. Biological Reviews of the Cambridge Philosophical Society. 64: 93-157.

Jamieson BGM. 1991. Fish Evolution and Systematics: Evidence from Spermatozoa. Cambridge University Press, Cambridge, U.K.

Jamieson BGM, MSY Lee, and K Long. 1993. Ultrastructure of the spermatozoon of the internally fertilizing frog Ascaphus truei (Ascaphidae: Anura: Amphibia) with phylogenetic considerations. Herpetologica, 49, 52-65.

Rouse GW, and BGM Jamieson. 1987. An ultrastructural study of the spermatozoa of the polychaetes Eurythoe complanata (Amphinomidae), Clymenella sp. and Micromaldane sp. (Maldanidae), with definition of sperm types in relation to reproductive biology. Journal of Submicroscopic Cytology and Pathology, 19, 573-584.

Scheltinga DM, BGM Jamieson, KE Eggers, and DM Green. 2001. Ultrastructure of the spermatozoon of Leiopelma hoschostetteri (Amphibia, Anura, Leiopelmatidae). Zoosystema 23:157-171.

Teixeira RD, GR Colli, and SN Báo. 1999. The ultrastructure of the spermatozoa of the worm-lizard Amphisbaena alba (Squamata, Amphisbaenidae), and the phylogenetic relationships of amphisbaenians. Canadian Journal of Zoology 77:1254-1264.

My practical experience with frog and lizard ecology have so far gone little beyond natural history observations and basic descriptive ecology. Reproduction, diet, morphometrics, and space use have been topics I have worked on. Granted, this kind of information is lacking for the great majority of South American herpetofauna.

Specifically, I have worked on Pseudis bolbodactylus diet an space use (Brandão et al., 2003), reproduction, morphometry, and diet of Hoplocercus spinosus

Bibliography

Brandão RA, Garda AA, Braz V, and Fonseca B, 2003. Observations on the ecology of Pseudis bolbodactyla (Anura, Pseudidae) in central Brazil. Phyllomedusa, 2(1): 3-8. Download PDF.

Garda AA, Colli GR. Aspectos da Ecologia de Hoplocercus spinosus no Cerrado do Brasil central. In: XXIII Congresso Brasileiro de Zoologia, 2000, Cuiabá, MT. XXIII Congresso Brasileiro de Zoologia. 2000. p. 529.

 Frog Phylogeny and Biogeography

Another interesting aspect of this group is their dependence on permanent ponds and the apparent restriction of some species to certain hydrographic basins, such as P. tocantins, which is found only along the domains of the Tocantins and Araguaia basin in Brazil, and L. caraya, restricted to the Araguaia river.

In my dissertation I intent to study the historical relationships among all nine species of Pseudinae, using morphological and molecular markers data.  Once a consistent phylogeny of the group is achieved, several hypothesis can be tested.  Mainly, the links between the history of South America's hydrographic basins and the speciation events in the group, as well as general hypothesis that account for the diversity of tropical environments.

Furthermore, I plan to map Pseudines distribution in South America and use prediction models to infer theoretical ranges based on environmental characteristics of current known localities, such as rainfall, vegetation, soil, etc.

Therefore, I will be able to assess these frogs biogeography based on both historical and environmental factors. The differences between these inferences may be due to local extinction, intraspecific competition and historical events that took place in the diversification of the group.

At last, I am working on population genetics of P. tocantins, a species occurring in the Araguaia-Tocantins river system. On the west side, the Araguaia marks the boundaries of the Amazon and Cerrado, with it's calm and wide waters forming a large and remarkable beautiful flood plain. The Tocantins, on the other hand, runs through the Cerrado on hilly areas with few ponds associated to it's margins.

I intent to assess the likely genetic differences in these two rivers, as well as to take a glance on geographic variation in genetic and morphological traits, which will be fundamental when addressing species limits within the group. At last, I will be able to infer male and female migration and evaluate the possible consequences of the recent damming of the Tocantins river and

Taxonomy