Michael S. Taylor

Southeast Missouri State University


puncticulatusMy research theme broadly embraces the genetical and ecological processes that can generate or maintain reproductive isolation between populations, which may lead ultimately to the evolution of new species. While many species groups would serve admirably as a study system, the majority of my research combines my fascination for fishes with a simple love of the ocean.

Speciation in the marine environment is an especially engaging research topic for several reasons. First, the oceans harbor a wealth of organismal diversity. Some oceanic habitats, such as tropical coral reefs, are rivaled only by rain forests for overall species richness. This organismal diversity is reflected by a plethora of life history traits, which may include pelagic gametes or larvae that impart the potential to disperse great distances on oceanic currents. This dispersal capability directly influences the extent of gene flow among populations, and thus influences the potential formation of new species. Second, marine species display a variety of biogeographic distributions, from linear distributions along coastlines to endemism on remote oceanic islands. Finally, the presence of few geographic barriers, coupled with co-occurring sister species, suggests that mechanisms other than geographical isolation may influence the formation of species in the ocean realm.

In the marine realm, no group of fishes is more diverse than the gobies. Gobies, with roughly 2000 described species, comprise the largest family (Gobiidae) of fishes in the oceans, as well as one of the largest families of all fishes. Gobies range in size from 8 mm (the smallest vertebrate in the world) to 60 cm or more. They occupy many different aquatic habitats, even tidal mud flats, with modifications to the eyes and skin that allow them to see and breathe outside of the typical aquatic environment. Gobies may be associated with the substrate or hover in the water column; they may be drab or very colorful. They may live alone, or form symbiotic relationships with other animals. For these, and may other reasons, gobies are proving to be an ideal group for research on the speciation process.

CaribAusI am particularly attracted to the study of gobies in the Neotropical region of the western Atlantic and eastern Pacific oceans. In the Neotropics, gobies are the most species-rich family of fishes. The high diversity of these fishes seems paradoxical for three principle reasons. One, this region is geographically compact. The Caribbean Sea, for example, spans roughly 3000 km from Barbados to Belize yet it is smaller than Australia (see right) or the Indonesian archipelago. The Neotropical region is especially diminuitive when compared to the roughly 25,000 km span of the Indo-Pacific. Two, the Neotropical seas are unsundered by obvious geographical barriers, with the exception of the Isthmus of Panama. Finally, strong currents may facilitate the transport of eggs and larvae across the region. Together, these three factors create the potential for high levels of gene flow via dispersal along coastlines and among islands. Thus, the paradoxical origins of Caribbean species diversity are a prime system for evolutionary exploration.

Below are brief summaries of my research areas, with links to greater detail.

Speciation and Coloration

What factors govern the origins of species diversity in coral reef fishes? Are sister species alloaptric or sympatric? Are sister species ecologically similar, or do they have different niches? Do the bright colors of reef fishes play a role in speciation? To address these questions, I apply comparative phylogenetic and phylogeographic analyses to mitochondrial and nuclear gene sequences, using gobies as a model system.

Gene Flow and Biogeography


My research with Elacatinus gobies suggests that larvae do not disperse on oceanic currents but instead are retained at their natal populations, which is supported by strong genetic structure among Caribbean island populations. Does this pattern recur in other reef fishes? Does species richness within a genus correspond to realized population genetic structure within species?

Goby Systematics

E. randalli

Recent and ongoing genetic and morphological work suggests that systematic revision of Elacatinus, Bollmannia and other gobies is warranted.

Photo Credits
Elacatinus puncticulatus photo copyright © Norihiro Yoshida from Goby Frontiers.
Elacatinus evelynae photo copyright © Paul Humann with New World Publications.
Malacoctenus boehlkei photo copyright © Jim Christensen with uwphoto.net.
Elacatinus randalli photo copyright © Paul Humann with Marine Life Images.

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     Gene Flow