Karen A. Kellogg

Evaluation of female mate choice cues in a group of lake Malawi Mbuna (Cichlidae)

Abstract The mechanisms that underlie the diversity of cichlids in the East African Great Lakes are poorly understood. Sexual selection through female choice based on male body coloration has often been suggested as a driving force behind the speciation of these fishes. The objectives of this study were to investigate, through mate choice trials, the cues that guide species-isolating female choice. In a group of sympatric Lake Malawi mbuna (rock-dwelling fish), we investigated both visual and chemical cues that might guide female choice by giving gravid females a choice between a heterospecific and a conspecific male. Visual cues, in contrast to olfactory cues, were sufficient to stimulate courtship and thus guide female choice of males. Furthermore, in contrast to other studies on related species, we found that females courted only with conspecifics even if color was not a cue. Species-isolating female choice is likely based primarily on visual information.

Experimental Evidence of Female Choice in Lake Malawi Cichlids

Abstract To date, most research on sexual selection has focused on the discrimination between attributes of individuals of the opposite sex. We have demonstrated female discrimination of a male behavioral character, bower size, by experimentally manipulating bower height in a lek of cichlid fishes from Lake Malawi, Africa. Eggs increased significantly (p<0.01) with large (15 cm) and extra large (30 cm) artificial bowers. Males with extra large bowers received a 50% greater increase in eggs laid than those with just large bowers.

Habitat Shift of a Native Darter Etheostoma Olmstedi (Teleostei: Percidae) in Sympatry with a Non-Native Darter Etheostoma Zonale

Abstract Etheostoma zonale, the banded darter, was introduced to the Susquehanna River basin of Pennsylvania through an interbasin transfer, or transplantation of native fishes outside their natural range. We examined the habitat use of a darter native to the Susquehanna River drainage E. olmstedi, the tessellated darter, in sympatry and allopatry with E. zonale to determine if its habitat use was different. In the presence of E. zonale, E. olmstedi occupied significantly (P < 0.05) shallower habitats (mean depth < 27 cm) with smaller substrates (mean substrate index < 32) and slower water velocities (mean water velocity < 0.13 m s−1) than in sites without E. zonale. The habitat shift of E. olmstedi was accompanied by a compression of niche breadth. The results are consistent with the hypothesis that E. zonale excludes E. olmstedi from riffle and run habitats, restricting E. olmstedi to shallow pools and stream margins.

Description of a New Species in the Pseudotropheus williamsi Complex (Teleostei: Cichlidae), from Lake Malawi, Africa

Abstract A new species of the cichlid genus Pseudotropheus Regan (Teleostei: Cichlidae), from Lake Malawi is described. The new species is a member of the Pseudotropheus williamsi complex from Mbenji Island. Pseudotropheus williamsi is the type species of the genus Pseudotropheus, which is a polyphyletic grouping of several species of rock-dwelling cichlids from Lake Malawi. In addition to the P. williamsi complex, Pseudotropheus contains species belonging to the P. tropheops, P. elongatus, and Pseudotropheus aggressive complexes, as well as a group of miscellaneous forms such as Pseudotropheus fainzilberi. We predict that Pseudotropheus eventually will be restricted taxonomically to include only members of the P. williamsi complex, but because of the lack of phylogenetic data on many of the miscellaneous forms (e.g., P. fainzilberi) we are currently unable to diagnose Pseudotropheus as monophyletic.

The Influence of Turbidity on Prey Consumption in the Tessellated Darter

AbstractIncreased turbidity and the resulting decreases in water clarity have been shown to alter fish foraging behaviors in potentially detrimental ways. Given the ecological importance of darters of the genus Etheostoma and their dependence on visual cues, we examined the impact of a range of turbidity levels (3.5, 6, 10, 20, 22, and 25 nephelometric turbidity units [NTU]) on the number of prey consumed by the Tessellated Darter Etheostoma olmstedi. While a study of the Fountain Darter E. fonticola found that turbidity affected prey consumption at slightly elevated levels (≥8.7 NTU), we found no significant differences in consumption by the Tessellated Darter across turbidity levels. While there may be intragenus variation in the use of olfactory cues, another and perhaps more likely explanation is the difference in long-term exposure to a range of turbidities. The Fountain Darter is endemic to clear, primarily spring-fed rivers, whereas the Tessellated Darter is, comparatively speaking, a generalist th...