Vampires on vampires?: Coevolution of bats and bat flies

2009 REU Intern Anna Sjodin


Sophomore Biology and Ecology major at Loyola University

FMNH REU Mentors: Dr. Bruce Patterson (MacArthur Curator, Zoology/Mammals) and Dr. Carl Dick, (Postdoctoral Fellow, Zoology/Insects)

Symposium Presentation Title: The Vampire’s Vampire: Bats and Blood-Feeding Fly Parasites (Chordata: Mammalia: Chiroptera: Phyllostomidae; Arthropoda: Hexapoda: Diptera: Hippoboscoidea)

Symposium Presentation Abstract: Bats constitute a single, extensive radiation of evolutionary lineages, trophic strategies, roosting structures, and social behaviors, and are parasitized by blood-feeding flies that vary in the reduction and loss of eyes and wings, flattening or narrowing of bodies, and the development of holdfast organs.  Coupled, bats and bat flies represent a model system for evolutionary studies.  My research included a morphometric study of the bat genus Sturnira, and a study of how bat fly eyes vary among the roosting structures utilized by their hosts.

Because boundaries among species of Sturnira are dubious, I used geometric and traditional morphometrics to evaluate shape and form of Sturnira skulls.  Differences in cranial characters among six Sturnira species were clearer using traditional morphometrics, and results expanded our current knowledge regarding differences between Sturnira species by providing a basic comparison between the shapes and forms of the skulls of each species.  Given minimal morphological data and unclear boundaries in the bat genus Sturnira, I was able to clarify lines between species by defining morphological characteristics.

Because several measures of parasitism are related to the roosting characteristics of bat hosts, I evaluated trends in bat fly eye complexity among hosts that varied in the roosts they utilize.  I measured eye size and counted the number of facets for >120 species of Venezuelan bat flies, and correlated these variables with roost type ranked along a gradient of enclosed and durable to exposed and ephemeral.  Both eye characters were negatively and significantly associated with roost type, suggesting that bat flies of bats that use dark and durable roosts have evolved less complex eyes than their counterparts on hosts roosting in locations exposed to light.  This study provided insight into the evolutionary development of eyes in cave organisms, and highlighted the importance of host roosting dynamics in the evolution of bat parasites.

Original Project Description: One group of flies has become obligate ectoparasites of bats, taking blood meals and living in the fur and on wing membranes. They show many adaptations for parasitic life, including reduced eye facets and wings and a highly modified life history. Incredibly, most bat flies are known to only infest a single species of bat. A recent faunal survey in Peru documented 93 species of bats, and on them 20 genera and 64 species of bat flies, including 9 new to science. Describing the new species and assessing their interrelationships is an ongoing process. Similar surveys are underway in Madagascar, Tanzania, and (in the planning stages) Borneo.

Research methods and techniques: REU participants in the project will receive an introduction to bats and their roosting ecology, bat flies and their morphology, systematics, and taxonomy. Participants will dissect and prepare specimens for microscopy, document diagnostic characters with optical and scanning microscopy, and record qualitative characters and collect morphometrics data from microscopic specimens. Time permitting, participants will participate in statistical and phylogenetic analyses.