Laura Howell

Defense Date

7-20-2007

Graduation Date

Fall 2007

Availability

Immediate Access

Submission Type

thesis

Degree Name

MS

Department

Biological Sciences

Committee Chair

Brady Porter

Committee Member

Lisa Ludvico

Committee Member

Michael Jensen-Seaman

Keywords

Phylogeography, Spawning, Conservation, Turbidity, Site fidelity, Nothonotus

Abstract

Little is known about the breeding parameters and population structure of three Pennsylvania darters, the bluebreast darter, Etheostoma camurum, the spotted darter, E. maculatum, and the Tippecanoe darter, E. tippecanoe. All are Pennsylvania state threatened species, and they are considered threatened or endangered in several other states throughout their range. Although some limited breeding information is available from populations in other states, the timing and duration of spawning has not been documented for Pennsylvania populations of E. camurum and E. tippecanoe. Both species occupy disjunct riffle habitats in the Allegheny River system, with stable populations in French Creek. We have found an additional population for these species about 110 miles downstream in Deer Creek, Harmarville, PA. Through weekly catch-and-release sampling of this population, we have identified the peak breeding times and the duration of the breeding season for the Deer Creek populations of these two species. Observations of population peaks indicate possible seasonal migrations into spawning areas. Spawning terminated for both species when temperatures exceeded 23 C for several days. Turbid conditions may influence spawning site occupation. Both species show strong site fidelity within the spawning riffle irrespective of depth or flow. Genetic analysis using the mtDNA ND2 gene indicates little population structure for all three species across their entire range. Seven new site records within the Allegheny River drainage suggest possible current gene flow through river-corridor migration and the possibility of the populations spreading from source population(s) in the Allegheny River to sink populations or seasonal breeding habitats in suitable tributaries. Population structure will be useful to conservation efforts by identifying the degree of population fragmentation between isolated populations. Breeding times and an understanding of factors that inhibit spawning will be a useful guide for ecologically responsible development of riparian areas, assisting with avoiding disturbances to important spawning areas during the breeding season.

Format

PDF

Language

English

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