Using molecular genetic techniques to detect outcrossing in natural populations of a self-fertilizing fish
<p>The hermaphroditic fish, Rivulus marmoratus, is the only vertebrate known to reproduce by internal self-fertilization; this process results in populations of homozygous clones. Most natural populations consist entirely of hermaphrodites, but phenotypically distinct, fertile males occur at f...
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| Format: | Others |
| Language: | en |
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Virginia Tech
2014
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| Online Access: | http://hdl.handle.net/10919/43487 http://scholar.lib.vt.edu/theses/available/etd-06302009-040321/ |
| Summary: | <p>The hermaphroditic fish, Rivulus marmoratus, is the only
vertebrate known to reproduce by internal self-fertilization; this
process results in populations of homozygous clones. Most natural
populations consist entirely of hermaphrodites, but phenotypically
distinct, fertile males occur at frequencies up to 24% on some islands
off the coast of Belize. The presence of large numbers of males in
natural populations prompted this study to determine if males are
involved in the mating system. The occurrence of cross-fertilization
between males and hermaphrodites was determined by surveying
progeny of field-caught hermaphrodites for non-segregation or
segregation of DNA fingerprint markers as an indication of the
homozygosity or heterozygosity of the parent.</p>
<p>
DNA fingerprinting revealed no segregation of markers among
the offspring in 12 of 12 Florida and Brazil laboratory lines and in 5
of 30 Belize Cay broods. These data indicate that the hermaphrodite
parents were homozygous; thus, no detectable outcrossing has
occurred in these populations. However, DNA fingerprinting revealed
segregation of markers among the offspring in 25 of 30 Belize Cay
broods. Twenty-four of these broods were from the island of Twin
Cays. An average of 30% of the parental bands were segregating
among the offspring; values ranged from 0.09 to 0.50. Offspring
were, on average, 8% dissimilar to one another; values ranged from
2.08% to 15.09%. These data suggest that the 25 hermaphrodite
parents were heterozygous; thus, males are involved in the mating
system in some Belize Cay populations. These data are the first
evidence of outcrossing in this species.</p> === Master of Science |
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