PhD Program in Biology, The Graduate Center, City University of New York

Ecology, Evolutionary Biology and Behavior

[This page is under construction.]

Valéria Tavares

Graduate Fellow, American Museum of Natural History
and City College
email: tavares@amnh.org and valtavares@hotmail.com

M.Sc. in Ecology, Conservation and Management of Wildlife, 1999, Universidade Federal de Minas Gerais, Belo Horizonte
B.Sc. in Verterbrate Zoology, 1995, Universidade Federal de Minas Gerais

Mentor: Nancy B. Simmons, Ph.D.
Thesis topic: My thesis research consists on a comprehensive systematic revision of Vampyressa (sensu Koopman, 1984) complex, and on a phylogenetic analysis of stenodermatine bats (Chiroptera: Phyllostomidae) at a generic level.

Summary of research interests:

• Chiropteran Systematics and Phylogenetics: chiropteran systematics, evolution and biogeography focusing on Neotropical bat families.
• Ecology and functional morphology: Functional morphology, ecomorphology and the study of bat communities at the Neotropical Atlantic forest.
• Natural history and taxonomy of Neotropical bats.

Current Research Summary:

I am working in collaboration with Dr. Nancy Simmons on the phylogenetic relationships and biogeography of a subtribe of stenodermatine bats known as “short-faced bats” (Chiroptera: Phyllostomidae) based on morphological characters and data from the literature on karyological and molecular characters. The Tribe Stenodermatina includes eight genera of frugivorous phyllostomid bats (Ametrida, Ardops, Ariteus, Centurio, Phyllops, Pygoderma, Sphaeronycteris, and Stenoderma) that together form a well-supported clade within Stenodermatinae. We have been also investigating the evolution of sexually dimorphic characters within the tribe.

Another project I am currently working focus on the biology of one short-faced species, Pygoderma bilabiatum (Chiroptera: Phyllostomidae). This research is based on natural history data from my previous fieldwork in Brazil and museum specimens from the USA and Latin America.

A third project in progress is the subject of my doctoral thesis research. It focuses on the revisionary systematics and phylogenetic relationships of another group of stenodermatine bats, the Vampyressa complex (Chiroptera: Phyllostomidae). Vampyressa are small-bodied yellow-eared fruit bats distributed through the Neotropical region. Although the genus is currently recognized as comprising three subgenera and five species, recent results of phylogenetic analysis have pointed out the non-monophyly of the Vampyressa - a group here called as “Vampyressa complex”—but none of the studies to date had sampled all species of Vampyressa. The project includes a true revision of Vampyressa (sensu Koopman 1994), including reevaluation of species limits because there might well be additional species involved, and not only the 5 presently recognized. I plan to study the phylogenetic relationships within the Vampyressa complex and between this genus and other long-faced stenodermatine bats (subtribe Ectophylina; e.g. Ectophylla). I intend to use morphological and ecological data to provide a detailed study of the evolutionary radiation and aspects of the biogeography of this group of bats. Molecular data might eventually be included in the analysis focusing in helping to resolve relationships at the species level.

In addition to my research in phylogenetics, I also conduct collaborative work in community ecology, functional morphology, and general aspects on natural history of Brazilian bats.

Publications, monographs, published abstracts:

Tavares, V.C. 1999. Flight Morphology, diet, and composition of a bat assemblage (Mammalia: Chiroptera) at the Rio Doce state Park, Southeast Brazil. Chiroptera Neotropical, 5(1-2): 117-118.

Tavares, V.C. 1999. Ecomorfologia do Vôo, dieta das espécies e composição de uma taxocenose de Morcegos (Mammalia: Chiroptera) do Parque Estadual do Rio Doce, leste de Minas Gerais, Sudeste Do Brasil. Master thesis. Ecology, Conservation and Wildlife Management, Belo Horizonte, MG, Brazil.

Tavares, V.C., and M. Anciães. 1998. Artificial Roosts and Diet of Some Insectivorous Bats in the Parque Estadual do Rio Doce, Brazil. Bat Research News, 39(3):142.

Tavares, V. C, F. A. Perini and J. A. Lombardi. 1998. Preliminary assessment to aspects related to the diet and wing morphology of bat communities in a reserve in Southeast Brazil. Bat Research News, 39(3): 111.

Azevedo, A. A., P. M. Linardi, V. C. Tavares and J. L. Souza. 1998. Batflies (Strebilidae and Nycteribiidae) parasites of bats from the “Parque Estadual do Rio Doce,” East of Minas Gerais, Brazil. Bat Research News, 39(3): 112.

Azevedo, A. A., P. M. Linardi, M. T. Z. Coutinho, V. C. Tavares and J. L. Souza. 1998. Interrelationships between Acari and bats (Mammalia: Chiroptera) in the “Parque Estadual do Rio Doce,” East of Minas Gerais, Brazil. Bat Research News, 39(3): 112.

Redondo, R. A., V. C. Tavares and M. H. Marcos. 1998. Variation in the fur color of Desmodus rotundus(É. Geoffroy, 1810) (Phyllostomidae: Desmodontinae) in the Parque Estadual do Rio Doce, east of Minas Gerais, Southeast of Brazil. Bat Research News, 39(3): 113.

Tavares, V. C. 1997. Aspectos da biologia de Pygoderma bilabiatum (Phyllostomidae: Stenodermatinae). Boletim Informativo da Sociedade Brasileira de Mastozoologia, 30.

Tavares, V. C. 1995. Aspectos da Biologia de Pygoderma bilabiatum. Monograph, B. A. (Vertebrate Zoology), Universidade Federal de Minas Gerais, Belo Horizonte, M.G., Brazil. (Advisor: Dr. Gustavo A. Bouchardet da Fonseca)

- in preparation - Coming soon...

Tavares, V. C., and N. B. Simmons. 2001. The evolution of sexual dimorphism in short faced bats: a Phylogenetic perspective. 31th Annual North-American Symposium on Bat Research, Program and Abstracts: 70-1.

Tavares, V. C., and N. B. Simmons. 2000. Phylogenetic relationships and biogeography of short-faced stenodermatine bats: preliminary results and hypotheses. 30th Annual North American Symposium on Bat Research, Program and Abstracts: 70-1.

Tavares, V. C., F. A. Perini and J. A. Lombardi. 1998. Preliminary assessment to aspects related to the diet and wing morphology of bat communities in a reserve in Southeast Brazil. Abstracts of the 11th International Bat Research Conference. Pirenópolis, GO.

Tavares, V. C., F. a. Perini, A. A. Azevedo, M. H. Marcos and J. A. Lombardi. 1998. Observações sobre a dieta de quirópteros do Parque Estadual do Rio Doce, leste de Minas Gerais, sudeste do Brasil e novos registros de morcegos para a região. Abstracts of the XXII Congresso de Zoologia, Recife, PE, Brazil.

Tavares, V. C. and M. Anciães. 1997. Artificial roosts utilization by bats (Vespertilionidae, Emballonuridae, Phyllostomidae) in the Parque Estadual do Rio Doce, Minas Gerais, Brazil. Abstracts of the Seventh International Theriological Congress, ITC-7, Acapulco, Mexico.

Tavares, V. C. 1995. Aspects of the Biology of the Ipanema Bat Pygoderma bilabiatum (Phyllostomidae), in a Brazilian Reserve. Abstracts of the 10th International Bat Research Conference, Boston, MA, EUA.

Recent abstracts:

The evolution of sexual dimorphism in short faced bats: a Phylogenetic perspective
Valeria C. Tavares and Nancy B. Simmons. 2001.31 North American Symposium on Bat Research, Victoria, British Columbia, Canada.

The Tribe Stenodermatina comprises eight monotypic genera of "short-faced" frugivorous phyllostomid bats, with four Central-South American broadly distributed species and four Antillean endemics nested as a clade within Stenodermatinae. These bats are the only phyllostomids that present remarkable sexual dimorphism, which evolved in different ways within the tribe either in both or in one of the sexes in each species. Females are considerably larger than males in all Antillean genera, and in the mainland Pygoderma and Ametrida. In contrast, males and females of Centurio and Sphaeronycteris are not dimorphic in size. However males of all mainland species, which includes the later two, present a variety of unusual secondary sexual characteristics, such as the development of the pendulant chest gland in A. centurio, and the submandibullary gland in Pygoderma and Centurio. We used character mapping onto a phylogeny provided by a combined matrix of molecular and morphological characters to investigate patterns of variation related to the evolution of sexual dimorphism within short-faced bats. As an initial hypothesis, we treated sexual dimorphism as an additive multistate character, under the assumption that it had evolved in concert, affecting males and females simultaneously. The rechecking (congruence analysis) of this first hypothesis led us to treat each trait in dimorphic males as separate characters, as well as the evolution of size in females. This suggests that different selection pressures might have acted in the two sexes. A third hypothesis yields the recode into two characters that most parsimoniously explain variation within Stenodermatina: a character related to size selection in females, and another describing dimorphic features in males. Although distinct structures (apparently non-homologous) account for the differentiation of sexual characters in males, those are consistently found in a clade formed by all mainland genera. Whereas evolutionary scenarios for the evolution of dimorphic characters in males should probably involve sexual selection, it seems difficult to choose among competitive hypothesis that could account for the phenomenon of large sized females: 1) given the paucity of behavioral and ecological data for short-faced bats, 2) given that many different factors other than those related to sexual selection are likely to underlie the evolution of larger females. Short-faced bats present a unique opportunity for investigating the evolution of large sized females among mammals due to the non-overlapping dimorphism they present, best exemplified by Ametrida centurio, the most extreme case within the order Mammalia.

Filogenia Da Tribo Stenodermatina (Chiroptera: Phyllostomidae) baseada em caracteres Morfológicos
Valéria C. Tavares. 2001. First Brazilian Congress on Mammalogy, Porto Alegre, Rio Grande do Sul, Brazil.

A Tribo Stenodermatina inclui os morcegos stenodermatíneos frugívoros conhecidos popularmente como "short-faced", devido a extrema compressão antero-posterior do crânio destes morcegos. Incluídos nesta tribo estão sete gêneros monotípicos cujas espécies são Ametrida centurio, Ardops nichollsi, Ariteus flavescens, Centurio senex, Pygoderma bilabiatum, Sphaeronycteris toxophyllum e Stenoderma rufum e um gênero (Phyllops) com dois representantes: P. falcatus e uma espécie fóssil, P. vetus. Quatro destes gêneros são endêmicos de ilhas nas Antilhas menores, enquanto que os demais são continentais, com distribuições entre as Américas do Sul e/ou Central. Muito pouco se conhece sobre a história natural e evolutiva destas espécies, que só recentemente foram consideradas em conjunto como constituintes de uma mesma tribo, devido a evidências sobre a monofilia do grupo. Este estudo apresenta a análise das relações filogenéticas da tribo Stenodermatina, através de análises de parcimônia, incluindo e excluindo a espécie fóssil e utilizando caracteres baseados em análises morfológicas de glândulas, pelagem, crânio, pós-crânio, dentição, quiropatágio, entre outros. Carollia brevicauda, Sturnira lilium, Uroderma bilobatum, Artibeus (Demanura) cinereus e Vampyressa bidens foram escolhidos como “grupos-externos” para a polarização dos caracteres. A monofilia dos “morcegos de rostro-encurtado” é reforçada por várias sinapomorfias, tais como a presença de um tufo de pelos brancos sobre os ombros, a ocorrência de um palato que não se extende em direção caudal além das inserções zygomáticas, entre outras. Estes morcegos são também únicos dentre os demais filostomídeos por apresentarem conspícuo dimorfismo sexual. Em algumas espécies, as fêmeas são muito maiores do que os machos; em outras, os machos apresentam caracteres sexuais secundários proeminentes; outras espécies ainda, apresentam uma combinação de diferenças de tamanho entre sexos e de caracteres sexuais secundários. Os gêneros com distribuição continental Ametrida, Centurio e Sphaeronycteris formam um clado, e Pygoderma aparece como grupo-irmão destes gêneros, enquanto que os gêneros distribuídos nas Antillhas parecem formar um outro clado. A filogenia do grupo parece consistente com uma hipótese recente sobre a paleogeografia da região do Caribe.

Phylogenetic relationships and biogeography of short-faced stenodermatine bats: preliminary results and hypotheses
Valéria C. Tavares and Nancy B. Simmons. 2000. 30 North American Symposium on Bat Research, Miami, Florida, USA.

The Tribe Stenodermatina includes eight monotypic genera of "short-faced" frugivorous phyllostomid bats (Ametrida, Ardops, Ariteus, Centurio, Phyllops, Pygoderma, Sphaeronycteris, and Stenoderma) that together form a well-supported clade within Stenodermatinae. These bats are characterized by remarkable primate-like skull morphologies, considerable sexual dimorphism, and development of a variety of unusual secondary sexual characteristics (e.g., the “visor” in Sphaeronycteris). Four genera are Antillean endemics, while the other genera have broad mainland distributions in Central and/or South America. Little is known about the ecology, behavior, or evolutionary history of these unique bats. We present preliminary results of a phylogenetic analysis of Stenodermatina species based on morphological characters and data from the literature on karyological and molecular characters. Species of Carollia, Sturnira, Artibeus (Dermanura), Vampyressa and Uroderma were used as outgroups. Results of parsimony analyses confirm monophyly of Stenodermatina. Ametrida, Centurio, and Sphaeronycteris appear to form a clade, with Pygoderma as their sister-group. The Antillean endemic taxa apparently fall outside this clade of mainland taxa. Patterns of geographic distribution and phylogenetic relationships suggest a preliminary historical biogeographic hypothesis for the group that appears consistent with a recent paleogeographic reconstruction of changes in the Caribbean region since the Eocene.

Flight morphology, diet, and composition of a bat community (Mammalia: Chiroptera) at the Rio Doce state Park, Southeast Brazil
Valéria C. Tavares. 1999. Master Thesis abstract, Master Course in Ecology, Conservation and Wildlife Management, Universidade Federal de Minas Gerais, M.G., Brazil. (Published in Chiroptera Neotropical, 5(1-2), 1999).

Functional morphology is a valuable approach to understand the organism performance and fitness. This study examines some morphological features of the wings and tail membranes of phyllostomid bats in order to analyze the relationship between flight morphology and feeding preferences. Data is also presented on community structure and diversity, and the responses of some bat species to environmental disturbance. I studied the bat community in the Rio Doce State Park, the largest protected area of Atlantic Forest in the state of Minas Gerais, southeast Brazil. Bats were sampled through capture with mist-nets and by searching for diurnal roosts. Surveys of the bat fauna were carried out in three different areas which differed in their degree of disturbance through human activities: 1) Campolina—tall mature forest, 2) Secondary—a forest of intermediate disturbance, 3) Campo de Pouso—highly disturbed low secondary forest and open area. Chiropterochoric plants were recorded in each, examining their distribution and average height. The diets of the bats were determined through the analysis of fecal samples. The outstretched wings of live bats were also photographed in the field for morphological analysis. Cecropia glaziovi and Ficus spp. were important canopy species in the well-preserved area of tall forest (Campolina), with Piper being frequent in the understorey of both primary and secondary growth areas. Cecropia pachystachia was found in all of three areas but the tallest individuals, reaching the canopy, occurred in the Campolina area. Vismia magnoliifolia was recorded only in the most disturbed area (Campo de Pouso). Sixteen of 28 species of bats registered for the Park were new records. Five of them were found in diurnal roosts. The known geographic distributions of Micronycteris schmidtorum and Uroderma magnirostrum were expanded. The Campo de Pouso area was less diverse and showed the lowest evenness in terms of species composition and abundance. The Campolina area (tall mature forest) and the Secondary area (of intermediate disturbance) showed similar diversities, but evenness was higher in the latter. Cecropia and Ficus was the main dietary item of the Stenodermatinae fruit bats, and Piper was dominant in the fecal samples of Carollia perspicillata. Vismia magnoliifolia fruits were recorded as a food item for bats for the first time. The relative abundance of Desmodus rotundus, C. perspicillata and the presence/absence of Phyllostominae (with the exception of the genus Phyllostomus) were considered as potential indicators of the levels of habitat disturbance in the southeast of Brazil. The phyllostomid bats had variable Wing Loading (WL), generally low Aspect Ratio (AR), and large wing areas indicating high maneuverability. The Wing Area (S) increases more than expected with body mass for phyllostomid fruit bats. On the other hand, the WL increases less than expected with the increase in body mass. The low values of WL and the large wing areas of phyllostomids enable a slow and maneuverable flight. The AR was constant in relation to increase in body mass and was always low. Each of the phyllostomids was characterized in terms of their flight attributes. The bats considered here as typical of the understory (Caroliinae and Phyllostominae) were of small to medium body size, had a low WL and rounded (high values for the Wingtip Shape Index - TSI) to triangular wingtips (Phyllostominae, foliage-gleaning insectivorous bats). The fruit bats considered to be canopy foragers and the species with the most flexible foraging habitats (Stenodermatinae) had comparatively higher WL and rounded (in the case of “flexible bats”) or pointed wingtips (“canopy bats”). A niche matrix was produced, based on the foraging strategies, feeding preferences and relative abundance of each species, grouping them into foraging guilds and splitting them by body weight. Twelve foraging guilds were proposed for the bat community of the Park, based on a modified division of 10 guilds described previously. In this classification, phyllostomid fruit bats fell into three distinct guilds: the Canopy fruit bats—Cecropia and Ficus consumers with relatively high WL, variable AR (tending to low values), large wings with pointed wingtips, extremely agile with high maneuverability, the Understory fruit bats—Piper consumers with low WL and AR and rounded wingtips, and a highly maneuverable flight with the ability to hover, the Flexible fruit bats with a more generalized diet of fruits, presenting flight characteristics of the canopy bats, but frequently caught in disturbed areas. Ecomorphological studies of flight are an important tool for solving questions regarding resource use and microhabitat selection of Neotropical bat communities, since wing morphology evidently plays a very significant role in the interaction of bats with their habitat and food sources.

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