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What keeps an asexual fish species from taking over?

Date:
May 9, 2011
Source:
University of Chicago Press Journals
Summary:
When a red-bellied dace and a finescale dace (freshwater fish in the carp and minnow family) mate with each other, they produce a hybrid with a very special ability: it can reproduce asexually. This asexual hybrid should have a tremendous evolutionary advantage over its sexually reproducing forefathers. So why doesn't the hybrid dace take over?
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When a red-bellied dace and a finescale dace (freshwater fish in the carp and minnow family) mate with each other, they produce a hybrid with a very special ability: it can reproduce asexually. This asexual hybrid should have a tremendous evolutionary advantage over its sexually reproducing forefathers.

In sexual populations, two individuals need to get together to reproduce, but in asexual populations every individual can reproduce on its own, giving asexuals twice the reproductive potential. Theoretically, the asexual advantage should enable the hybrids to outcompete sexual dace living in the same pond. But in reality that doesn't happen. Sexual and asexual dace are known to live side-by-side.

So why doesn't the hybrid dace take over? According to a study by researchers from the University of British Columbia, it's because the hybrids aren't as healthy. Using swimming speed as a proxy for overall health, the researchers found that hybrids performed worse than at least one of the parent species in a series of speed tests.

The results suggest that at minimum, the hybrid has no physiological performance advantage over the sexual species, and is probably at something of a disadvantage. The lower physiological performance may counteract the hybrids' reproductive advantage, preventing them from taking over. The results offer one possible explanation for why sexual reproduction has stayed dominant in vertebrates

The research is published in the May/June 2011 issue of the journal Physiological and Biochemical Zoology.


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The above post is reprinted from materials provided by University of Chicago Press Journals. Note: Materials may be edited for content and length.


Journal Reference:

  1. Daniel W. Baker, Linda M. Hanson, Anthony P. Farrell, Colin J. Brauner. Exceptional CO2Tolerance in White Sturgeon (Acipenser transmontanus) Is Associated with Protection of Maximum Cardiac Performance during Hypercapnia In Situ. Physiological and Biochemical Zoology, 2011; 84 (3): 239 DOI: 10.1086/660038

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University of Chicago Press Journals. "What keeps an asexual fish species from taking over?." ScienceDaily. ScienceDaily, 9 May 2011. <www.sciencedaily.com/releases/2011/05/110502163318.htm>.
University of Chicago Press Journals. (2011, May 9). What keeps an asexual fish species from taking over?. ScienceDaily. Retrieved July 28, 2015 from www.sciencedaily.com/releases/2011/05/110502163318.htm
University of Chicago Press Journals. "What keeps an asexual fish species from taking over?." ScienceDaily. www.sciencedaily.com/releases/2011/05/110502163318.htm (accessed July 28, 2015).

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