Salinity tolerance of Oreochromis niloticus and O. mossambicus F1 hybrids their successive backcross / by Dennis Almazan Mateo.

By: Material type: TextTextLanguage: English Publication details: Miag-ao, Iloilo : University of the Philippines in the Visayas, 2002.Description: xv, 97 pages : illustrations ; 28 cmContent type:
  • text
Media type:
  • unmediated
Carrier type:
  • volume
Subject(s): DDC classification:
  • 639 M41 2002
Online resources: Abstract: The effect of backcrossing on the salinity tolerance of the offspring of the hybrid O. mossambicus (Mo) x O. niloticus (Ni) was determined using median lethal salinity (MLS) and optimum salinity tolerance (OST) as indices of tolerance. The reciprocal Hybrids 1 (H1)(Mo x Ni and Ni x Mo), the first hybridization, were backcrossed with parental O. mossambicus in reciprocal crosses (i.e. with O. mossambicus as mother or father) to produce the reciprocal Hybrids 2 (H2) (HI x Mo and Mo x H1), the backcross 1 and reciprocal Hybrids 3 (H3) (H2 x Mo and Mo x H2) and the backcross 2. These reciprocal hybrids and pure parental species were exposed to progressive changes in salinity at 6 ppt intervals until total mortality. Standard length (SL) was measured to correlate the size to salinity tolerance. Clinical signs and social behavior were observed during the test. Parental O. mossambicus showed the highest salinity tolerance, followed by reciprocal H3, H2 and HI, while parental O. niloticus had the lowest. There was an increase of salinity tolerance in the offspring as they were backcrossed to the saline-tolerant parent O. mossambicus. Both parents (O. mossambicus) contributed to the salinity tolerance of the offspring. Maternal inheritance was observed in reciprocal H1 and reciprocal H2, while paternal inheritance was observed in reciprocal H3. HI had the highest heterosis. Both H2 and H3 stocks had negative and slight positive heterosis, indicating that they are good candidates as base population for selection. Size and salinity tolerance were significantly related in H'2 and H'3 compared to the other group of fishes. Bigger fish survives longer in elevated salinities compared to smaller one. In the selection phase for growth, salinity tolerance might be indirectly selected, because larger fish survives longer regardless of age. Social behavior during acclimation to salinity was observed. Generally, there was a decrease in the dominance of dominant individuals with the increase in salinity. O. niloticus and HI stocks were increasingly aggressive at 30-36 ppt. H1 still had a residual dominant individuals until 96 ppt. Dominance disappeared in the other groups (H2 and H3 and pure O. mossambicus) at 48 ppt. Loss of dominance among dominant individuals, cessation of feeding/minimal food intake, sunken eyes and abdomen, color changes and sluggish movement were observed before fish mortality.
Star ratings
    Average rating: 0.0 (0 votes)
Holdings
Item type Current library Collection Call number Materials specified URL Copy number Status Notes Date due Barcode
Theses / Manuscripts Theses / Manuscripts Ladislao N. Diwa Memorial Library Theses Section Non-fiction 639 M41 2002 (Browse shelf(Opens below)) Link to resource copy 1 Room use only T-5963 00000001
Theses / Manuscripts Theses / Manuscripts Ladislao N. Diwa Memorial Library Theses Section Non-fiction 639 M41 2002 (Browse shelf(Opens below)) Link to resource copy 2 Room use only T-5971 00000002
Theses / Manuscripts Theses / Manuscripts Ladislao N. Diwa Memorial Library Theses Section Non-fiction 639 M41 2002 (Browse shelf(Opens below)) Link to resource copy 3 Room use only T-5972 00000003
Theses / Manuscripts Theses / Manuscripts Ladislao N. Diwa Memorial Library Theses Section Non-fiction 639 M41 2002 (Browse shelf(Opens below)) Link to resource copy 4 Room use only T-5993 00000004

Thesis (MS Fisheries -- Aquaculture) University of the Philippines in the Visayas

Includes bibliographical references.

The effect of backcrossing on the salinity tolerance of the offspring of the hybrid O. mossambicus (Mo) x O. niloticus (Ni) was determined using median lethal salinity (MLS) and optimum salinity tolerance (OST) as indices of tolerance. The reciprocal Hybrids 1 (H1)(Mo x Ni and Ni x Mo), the first hybridization, were backcrossed with parental O. mossambicus in reciprocal crosses (i.e. with O. mossambicus as mother or father) to produce the reciprocal Hybrids 2 (H2) (HI x Mo and Mo x H1), the backcross 1 and reciprocal Hybrids 3 (H3) (H2 x Mo and Mo x H2) and the backcross 2. These reciprocal hybrids and pure parental species were exposed to progressive changes in salinity at 6 ppt intervals until total mortality. Standard length (SL) was measured to correlate the size to salinity tolerance. Clinical signs and social behavior were observed during the test.

Parental O. mossambicus showed the highest salinity tolerance, followed by reciprocal H3, H2 and HI, while parental O. niloticus had the lowest. There was an increase of salinity tolerance in the offspring as they were backcrossed to the saline-tolerant parent O. mossambicus.

Both parents (O. mossambicus) contributed to the salinity tolerance of the offspring. Maternal inheritance was observed in reciprocal H1 and reciprocal H2, while paternal inheritance was observed in reciprocal H3. HI had the highest heterosis. Both H2 and H3 stocks had negative and slight positive heterosis, indicating that they are good candidates as base population for selection.

Size and salinity tolerance were significantly related in H'2 and H'3 compared to the other group of fishes. Bigger fish survives longer in elevated salinities compared to smaller one. In the selection phase for growth, salinity tolerance might be indirectly selected, because larger fish survives longer regardless of age.

Social behavior during acclimation to salinity was observed. Generally, there was a decrease in the dominance of dominant individuals with the increase in salinity. O. niloticus and HI stocks were increasingly aggressive at 30-36 ppt. H1 still had a residual dominant individuals until 96 ppt. Dominance disappeared in the other groups (H2 and H3 and pure O. mossambicus) at 48 ppt.

Loss of dominance among dominant individuals, cessation of feeding/minimal food intake, sunken eyes and abdomen, color changes and sluggish movement were observed before fish mortality.

Submitted to the University Library 05/27/2016 T-5963 copy 1

Submitted to the University Library 05/27/2016 T-5971 copy 2

Submitted to the University Library 05/27/2016 T-5972 copy 3

Submitted to the University Library 05/27/2016 T-5993 copy 4

Copyright © 2023. Cavite State University | Koha 23.05