Nest association, a symbiotic reproductive strategy in North American minnows, has long captured the interest of scientists because of brilliant nuptial coloration of associates. Subgenus Hydrophlox of genus Notropis historically contained nine species, all of which engage in nest association with varying levels of host specificity. To understand evolutionary trends in reproductive behavior within this group, I first tested the monophyly of Hydrophlox using multiple molecular genetic markers, and analyzed representative specimens from all putative members, and multiple populations of each species. I found that Hydrophlox is composed of five nominal taxa, Notropis rubricroceus, N. chiliticus, N. lutipinnis, N. chlorocephalus, and N. chrosomus, and also contains at least two undescribed forms within N. lutipinnis and N. chlorocephalus. Although natural hybridization is not uncommon among nest associates, some of the previously undescribed diversity in Hydrophlox is threatened by hybridization between N. chiliticus and N. chlorocephalus in the Catawba River. In one population, 40% of the individuals are hybrids and introgression is common. This is a potential threat to the genetic integrity of N. chlorocephalus, a species heretofore considered robust and secure from a conservation standpoint Members of the subgenus Hydrophlox are less diverse in their host preference than previously thought. Presence of nuptial males over a nest has been viewed by many as evidence of egg deposition. I observed 29 spawning aggregations throughout the range of three nest associates, and I was able to identify eggs collected from a subset of nest sites. Spawning of N. baileyi, N. rubricroceus, and N. chlorocephalus is strongly associated with Nocomis spp. Notropis rubricroceus nuptial males aggregating over Semotilus atromaculatus nests did not successfully spawn, likely a result of highly aggressive behavior by the resident male S. atromaculatus. Additionally, I frequently observed Campostoma spp. modifying Nocomis mound nests, a behavior not previously reported, and which may have led some to conclude Campostoma were hosts of spawning aggregations. A literature review, combined with these data, suggests Hydrophlox are obligate nest associates of Nocomis species. Comparisons of monophyletic clades of nest associates, such as Hydrophlox, and clades with no or few associates are now possible. Divergence times, habitat requirements, and community structure may now be compared, and will illuminate our understanding of this fascinating reproductive behavior / acase@tulane.edu
| Identifer | oai:union.ndltd.org:TULANE/oai:http://digitallibrary.tulane.edu/:tulane_25120 |
| Date | January 2010 |
| Contributors | Cashner, Mollie Frances (Author), Mayden, Richard L (Thesis advisor) |
| Publisher | Tulane University |
| Source Sets | Tulane University |
| Language | English |
| Detected Language | English |
| Rights | Access requires a license to the Dissertations and Theses (ProQuest) database., Copyright is in accordance with U.S. Copyright law |
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