SalinitySalinity ToleranceTolerance ofof OreochromisOreochromis niloticusniloticus andand O.O. mossambicusmossambicus F1F1 HybridsHybrids andand TheirTheir SuccessiveSuccessive BackcrossBackcross
Dennis A. Mateo, Riza O. Aguilar, Wilfredo Campos, Ma. Severa Fe Katalbas, Roman Sanares, Bernard Chevassus, Jerome Lazard, Pierre Morissens, Jean Francois Baroiller and Xavier Rognon Significance of the Study • Freshwater now becoming a scarce resource, with competing use for: • Domestic or household, agriculture and power generation.
• Future prospect in aquaculture: • Expansion to saline waters, unfit for domestic/household and agricultural uses. • Fish cage culture in saline waters. • Alternative species for brackishwater pond culture. • Tilapias are popular cultured species due to their high environmental tolerances. • Tilapias posses various characteristics which make them desirable species for brackishwater farming. • Consequently, for many years, tropical aquaculturists have tried to develop saline tilapia culture. • Unfortunately, the true brackishwater tilapias (e.g. O. mossambicus) have poor- growing performance while the fast- growing strains (e.g. O. niloticus) are poorly adapted to saline water environment.
• The usual practice of using F1 hybrids of the foregoing species failed. Why F1 hybrids failed?
• Difficult to maintain two pure species; small production due to incompatibility of breeders; and unsustainable mass production.
• With the foregoing reasons, there is a need to produce tilapia strains that can be bred in brackishwater.
• The creation of a synthetic strain can be produced through repeated backcrossing of the saline tolerant parent to their offspring. Why Backcrossing?
• Through backcrossing of saline tolerant parent to their hybrids, the salinity tolerance of the offspring is significantly increased.
• It creates a true breeding population that can be exploited in a selection process. General Objective of the Study
• To determine the salinity tolerance of the different hybrids and their pure parental species: • Oreochromis mossambicus • Oreochromis niloticus • Reciprocal Hybrids 1 • Reciprocal Hybrids 2 • Reciprocal Hybrids 3 Specific Objectives of the Study
1. To determine an increase of salinity tolerance of hybrids as they are backcrossed to their saline tolerant parent O. mossambicus. 2. To determine the relationship of size and salinity tolerance. METHODOLOGYMETHODOLOGY BREEDINGBREEDING STRATEGYSTRATEGY
! CombiningCombining twotwo speciesspecies withwith differentdifferent desirabledesirable traits:traits:
–– OreochromisOreochromis mossambicusmossambicus ((salinitysalinity tolerancetolerance),), andand –– OreochromisOreochromis ((fastfast growthgrowth raterate).).
niloticusniloticus GIFT Material from BFAR-Muñoz Wild Stocks Random Collection (Oreochromis niloticus) (Oreochromis mossambicus)
Selected 80 Breeders Selected 100 Breeders 1998
O.mossambicus O. niloticus M (Mo)
Crossbreeding
Mossambicus 1 (M1) 1999 Hybrid 1 INTEREST Backcross 1 OF MY STUDY
2000 Mossambicus 2 Hybrid 2 (M2)
Backcross 2
2001 Hybrid 3 Mossambicus 3 (M3)
Backcross 3
2002 Hybrid 4 Mossambicus 4 (M4)
Backcross 4
2003 Hybrid 5
Figure 1. Schematic diagram of Molobicus Project Oreochromis niloticus Oreochromis mossambicus
CROSSBREEDING
F1 HYBRID 1
H1A H1B H1C AlternateH1D H1E H1F UseM1A M1B M1CofM1D SexesM1E M1F Alternate Use of SexesMOSSAMBICUS 1
F1 H1 F'1H'1
BACKCROSS 1
F1 HYBRID 2
H2A H2B H2C H2D H2E H2F M2A M2B M2C M2D M2E M2F MOSSAMBICUS 2
F1 H2 F'1 H'2
BACKCROSS 2
F1 HYBRID 3
H3A H3B H3C H3D H3E H3F M3A M3B M3C M3D M3E M3F MOSSAMBICUS 3
F1 H3 F'1H'3
BACKCROSS 3
F1 HYBRID 4
H4A H4B H4C H4D H4E H4F M4A M4B M4C M4D M4E M4F MOSSAMBICUS 4
F1 H4 F'1 H'4 BACKCROSS 4
F1 HYBRID 5 Legend:
Male H5A H5B H5C H5D H5E H5F
F1 H5 F'1H'5 Female
Figure 2. Rotational backcrossing scheme to develop a saline-tolerant tilapia MethodologyMethodology
SetSet--upup toto produceproduce experimentalexperimental fishfish
Fish were Produced in 1 x 1.5 x 6 m hapa & 500-L aquaria MethodologyMethodology
Study 1: Salinity tolerance of the different treatments •8 treatments •4 replicatess •3 cm size (2 months old) •1 aquaria for the reserved fish in each treatment •20 liter water •21-liter capacity aquaria MethodologyMethodology
Study 2: Size and salinity tolerance correlation
•8 treatments •mixed sizes 1-6 cm •standard length •0.4 g / liter •75 liter water •100-liter capacity containers The Treatments
1 O. 1 O. mossambicusmossambicus 2 Hybrid 1 (O. ) 2 Hybrid 1 (O. mossambicusmossambicus ) 3 Hybrid ‘1 (O. ) 3 Hybrid ‘1 (O. niltocusniltocus ) ϕϕ 4 Hybrid 2 (Hybrid 1 ϕϕ XXϕϕ XX O.O. ) O.O.XX niltocus 5 Hybrid ‘2 (O. O.O.mossambicusmossambicus Hybridniltocus ‘1 σ 5 Hybrid ‘2 (O. mossambicusmossambicus mossambicusmossambicusHybrid ‘1 σ)) σσ 6 Hybrid 3 (O.O. mossambicus Hybrid 2 σσ)) mossambicus σσ σ 7 Hybrid ‘3 (Hybrid ‘2 ϕ X O. ϕϕ σ) 7 Hybrid ‘3 (Hybrid ‘2 ϕ X O. mossambicusmossambicusXX ) 8 O. ϕϕ 8 O. niloticusniloticus XX Legends: ϕ - female; σ - male σσ DataData AnalysisAnalysis
• Mean Salinity Tolerance = (f*1+f*2+…+fN*sN)/N (where f-fish; s-salinity; N-number of individuals) • Median Lethal Salinity (using linear regression) Y = a + bX • Optimum Salinity Tolerance (using break-line analysis) a1+b1X = a2+b2X • Heterosis (Douglas Tave) • Maternal/Paternal Inheritance (Douglas Tave) • Analysis of Covariance (initial wt as covariant) • Duncan’s Multiple Range Test (DMRT)
Note: Sigma Plot was used in Regression Analysis; SPSS10 was used in ANCOVA and DMRT. ResultsResults andand DiscussionsDiscussions Salinity Tolerance Index
Median Lethal Salinity (MLS)
Treatment Mean Std. Dev. 110 O. O. mossambicus 115.06 a 1.48 Hybrid 1 97.33 c 3.82 90
Hybrid ‘1 111.22 ab 0.87 Mean.MST Hybrid 2 112.14 ab 1.38 70 Hybrid ‘2 109.45 b 0.29 50 Hybrid 3 109.95 b 3.09 012345678 Hybrid ‘3 108.28 b 3.64 V6 O. O. niloticus 53.88 d 3.96 Salinity Tolerance Index Mean Salinity Tolerance (MST)
120 Treatment Mean Std. Dev. O. 100 O. mossambicus 118.20 a 0.5477
Hybrid 1 99.60 c 1.7146 80 Hybrid ‘1 112.50 ab 0.7937 Hybrid 2 115.50 ab 2.5500 (ppt) Salinity Lethal Median 60
Hybrid ‘2 110.85 b 2.0549 40
Hybrid 3 111.00 b 3.3317 012345678 Treatment Hybrid ‘3 108.75 b 2.2650 O. O. niloticus 56.85 d 2.0549 Salinity Tolerance Index MLS & MST
•O. mossambicus got the highest salinity tolerance. •O. niloticus got the lowest. •Hybrid 1 got next to the lowest (mother: O. niloticus). •H’1, H2, H’2, H3 and H’3 were not significant to each other. Salinity Tolerance Index Optimum Salinity Tolerance (OST)
Treatment Mean Std. Dev. O. 107.63 a 0.29 mossambicus 107.63 a 0.29 100 Hybrid 1 70.50 b 5.56 Hybrid ‘1 101.98 a 5.89 80
Hybrid 2 80.73 b 21.89 OST (mean) 60 Hybrid ‘2 76.14 b 18.63 Hybrid 3 101.94 a 4.22 40
012345678 Hybrid ‘3 94.54 ab 14.08 Treatment O. O. niloticus 40.83 c 4.68 Salinity Tolerance Index
Optimum Salinity Tolerance (OST)
•O. mossambicus, H3, H’3 and H’1 got the highest salinity tolerance. •H1, H2, H’2 and H’3 were the next group of highest salinity tolerance. •O. niloticus was the lowest. Salinity Tolerance Index
•The results show that there was an increase in salinity tolerance as they were backcrossed with O. mossambicus. Size and Salinity Tolerance Correlation
Treatment Linear equation R2 R n SE P (sig.) O. mossambicus y = 1.0486x + 110.56 0.06 0.24 33 5.62 0.17ns H1 (Mf x Nm) y = 5.4013x + 71.17 0.46 0.23 14 6.92 0.34ns H'1 (Nf x Mm) y = 5.7486x + 66.91 0.16 0.39 21 18.56 0.08ns H2 (Mf x H1m) y = 1.6592x + 106.85 0.14 0.00 23 14.69 0.07ns H'2 (H'1f x Mm) y = 6.2823x + 81.59 0.15 0.38 27 14.09 0.05* H3 (H2f x Mm) y = -0.0481x + 114.03 0.00 0.02 34 3.82 0.91ns H'3 (Mf x H'2m) y = 5.5904x + 84.70 0.16 0.39 27 19.84 0.04* O. niloticus y = 0.4937x + 57.17 0.04 0.19 40 5.64 0.22ns NsInfluence – not significant of Size to Survival in elevated* significant salinities showed 15% (H’2) and 16% (H’3). Size and Salinity Tolerance Correlation Slope Comparison Between Hybrid’2 &Hybrid’3
Slope comparison betw een Regression of Hybrid "3 and Hybrid "2
140 130 120 110 There was no 100 y(H'2) = 6.2824x + 81.586 90 R2 = 0.1456; n=27; p=0.049* significant 80 70 60 y(H'3) = 5.5905x + 84.705 2 = 0.1564; n=27; p=0.04* difference in the 50 R 40 test for slope: Salinity Tolerance (ppt) 30 tCom at 0.0137 < tTab(0.05) at 2.01 slope comparison 20 accept: slope of H'3 = slope H'2 10 0 between H’2 and 012345678 Size (cm, SL) H’3. Hy brid "3 Hy brid "2 Linear (Hybrid "3) Linear (Hybrid "2) Size and Salinity Tolerance Correlation
! Larger tilapias survived longer than smaller ones.
! This is due to the more matured osmoregulating parts like gills and kidney and matured hemoglobin, so more efficient in an environment with lower DO level like seawater. Heterotic Effect
Heterosis of the different Hybrids Hybrids OST MLS MST Hybrids 1 20.23 23.45 21.17 Hybrids 2 -20.23 1.025 0.94 Hybrids 3 5.60 -3.378 -5.02
• Hybrid 1 had the largest heterosis. • Hybrids 2 and 3 had slight positive and negative heterosis. • Note: Nearly zero heterosis is considered as additive inheritance. Heterotic Effect
• From the results of heterosis, Hybrids 2 and 3 are good candidates as base population for selection. Maternal / Paternal Inheritance
Difference of Salinity Tolerance on their Reciprocal Breeds Hybrids OST MLS MST Hybrids 1 +(25.48) +(13.89) +(12.9) Hybrids 2 +(4.59) +(2.69) +(4.65) Hybrids 3 -(7.4) -(1.67) -(2.25)
• Positive results show maternal inheritance. • Negative results show paternal inheritance. • Hybrid 1 had the biggest positive results showing a strong maternal influence. Maternal / Paternal Inheritance
• Hybrid 2 got lower positive results than Hybrid 1 but still showing maternal inheritance. • Hybrid 3 got negative results showing paternal inheritance.
• Both sexes contributed to the salinity tolerance of the hybrids as observed in H2 and H3. Maternal / Paternal Inheritance
• Maternal inheritance was greater than paternal inheritance as shown in H1 and H3 because it is a fact that eggs carry more extra-chromosomal genes in their cytoplasm as compared to the sperm of male. Effects of Backcrossing
Results show that Treatment MLS MST OST there was an O. O. mossambicus 115.06 a 118.20 a 107.63 a increase of Hybrid 1 97.33 c 99.60 c 70.50 b salinity tolerance Hybrid ‘1 111.22 ab 112.50 ab 101.98 a of the F1 hybrids Hybrid 2 112.14 ab 115.50 ab 80.73 b as they were Hybrid ‘2 109.45 b 110.85 b 76.14 b backcrossed to Hybrid 3 109.95 b 111.00 b 101.94 a their parent with Hybrid ‘3 108.28 b 108.75 b 94.54 ab a high salinity O. O. niloticus 53.88 d 56.85 d 40.83 c tolerance (O. mossambicus) Effect of Backcrossing
MLS Average (ppt) OST Average (ppt) Hybrids Offspring Parents Offspring Parents Hybrids 1 104.28 84.47 89.24 74.23 Hybrids 2 110.79 109.67 78.43 98.43 Hybrids 3 109.11 112.93 98.24 93.03
Increase in salinity tolerance is due to the introduction of more genes from the saline tolerant parent (O. mossambicus) to the hybrids. The process is called INTRODUCTORY CROSSING. Effect of Alternate Use of Sexes
Heterosis in the different Hybrids • Alternate use of Hybrids OST MLS MST sexes during Hybrids 1 20.23 23.45 21.17 breeding Hybrids 2 -20.23 1.025 0.94 reduced Hybrids 3 5.60 -3.378 -5.02 heterosis. Effect of Alternate Use of Sexes
Difference of Salinity Tolerance on • Alternate use of their Reciprocal Breeds sexes reduced Hybrids OST MLS MST the difference Hybrids 1 +(25.48) +(13.89) +(12.9) of salinity Hybrids 2 +(4.59) +(2.69) +(4.65) Hybrids 2 +(4.59) +(2.69) +(4.65) tolerance of the Hybrids 3 -(7.4) -(1.67) -(2.25) reciprocal breeds. Social Behavior of Tilapia During the Salinity Tolerance Test
• Dominant behavior of fish have been reported to: • Impose stress to other fish, • Prevent other fish to eat, • Utilize more energy by chasing and attacking other fish, and • Result in slow growth. • Observed Social Behavior During the Salinity Test • O. niloticus and Reciprocal Hybrids 1 were more aggressive than the other groups of fishes. • Therefore, Hybrids 1 are not good candidates as base population for selection due to their aggressiveness which can be transferred from parents to offspring. Inbreeding Values
• Three ancestors
M1 were applied in the
H2 M2 production of H3.
H3 • Inbreeding value 3 of H3 was 0.125, so Fx= [(0.5) ] a previous 12.5% 3 - # of ancestors involved heterozygous
Fx= 0.125 or 12.5 % genes became Simplified Path Diagram homozygous. Inbreeding Values
• Therefore H3 is M1 not fitted as base H2 M2 population for H3 selection due to 3 its high Fx= [(0.5) ] inbreeding value 3 - # of ancestors involved of 12.5%. F = 0.125 or 12.5 % x • Note: Allowable Simplified Path Diagram value is 5-10%. ConclusionsConclusions ! SalinitySalinity ToleranceTolerance –– ThereThere isis anan increaseincrease inin thethe salinitysalinity tolerancetolerance ofof hybridshybrids asas theythey werewere backcrossedbackcrossed toto O.O. mossambicusmossambicus (high(high salinitysalinity toleranttolerant parent).parent). ! SizeSize andand SalinitySalinity ToleranceTolerance –– LargerLarger fishfish areare moremore toleranttolerant thanthan smallersmaller fish.fish. –– ThisThis maymay bebe duedue toto thethe moremore maturedmatured osmoregulatingosmoregulating partsparts andand hemoglobinhemoglobin forfor oxygenoxygen distributiondistribution (respiration).(respiration). ! HeterosisHeterosis –– HybridsHybrids 22 andand 33 areare goodgood candidatescandidates asas basebase populationpopulation forfor selectionselection inin termsterms ofof HETEROSIS.HETEROSIS. ! MaternalMaternal andand PaternalPaternal InheritanceInheritance –– BothBoth sexessexes ofof O.O. mossambicusmossambicus contributedcontributed salinitysalinity tolerancetolerance toto thethe Hybrids.Hybrids. –– MaternalMaternal inheritanceinheritance isis greatergreater thanthan paternalpaternal inheritanceinheritance whichwhich maymay bebe duedue toto extraextra--chromosomalchromosomal genesgenes andand environmentalenvironmental influenceinfluence fromfrom thethe mother.mother. ! EffectEffect ofof BackcrossingBackcrossing andand AlternateAlternate UseUse ofof SexesSexes –– IncreasedIncreased salinitysalinity tolerancetolerance inin backcrossing.backcrossing. –– AlternateAlternate useuse ofof sexessexes inin backcrossingbackcrossing reducedreduced heterosisheterosis andand resultedresulted toto manageablemanageable maternalmaternal andand paternalpaternal inheritance.inheritance. ! InbreedingInbreeding ValuesValues –– HybridsHybrids 11 && 22 havehave zerozero (0)(0) inbreedinginbreeding values.values. –– HybridsHybrids 33 havehave 12.5%12.5% inbreedinginbreeding values.values. –– Therefore,Therefore, HybridsHybrids 33 willwill notnot fitfit asas basebase populationpopulation forfor selectionselection inin termsterms ofof inbreedinginbreeding values.values. ! SocialSocial BehaviorBehavior duringduring thethe SalinitySalinity ToleranceTolerance TestTest
–– O.O. niloticusniloticus andand Hybrid’1Hybrid’1 areare moremore dominantdominant thanthan thethe otherother groups.groups. ((ThisThis behaviorbehavior mightmight bebe transferredtransferred toto thethe offspring.offspring.)) –– HybridsHybrids 11 willwill notnot bebe goodgood candidatescandidates asas basebase populationpopulation forfor selectionselection inin termsterms ofof theirtheir aggressiveness.aggressiveness. ! GeneralGeneral ConclusionConclusion
–– ReciprocalReciprocal HybridsHybrids 22 willwill bebe bestbest fittedfitted amongamong thethe hybridshybrids asas basebase populationpopulation forfor selectionselection duedue to:to:
! lowlow heterosisheterosis,,
! lowlow aggressiveness,aggressiveness, andand
! zerozero inbreedinginbreeding values.values. RecommendationsRecommendations ! SizeSize andand salinitysalinity tolerancetolerance werewere significantlysignificantly correlatedcorrelated inin H’2H’2 andand H’3.H’3.
! Therefore,Therefore, selectionselection ofof fastfast growinggrowing onesones isis recommendedrecommended asas breedersbreeders becausebecause sizesize andand salinitysalinity tolerancetolerance areare significantlysignificantly correlated.correlated. ! OptionsOptions asas basebase populationpopulation forfor selectionselection
–– OptionOption 1:1: forfor –– OptionOption 2:2: forfor largelarge hatcherieshatcheries mediummedium hatcherieshatcheries
! 70 % Hybrids 2 ! 60 % Hybrids 2
! 20% hybrids 3 ! 40% hybrids 3 ! 10% hybrids 1
–– OptionOption 3:3: forfor –– OptionOption 4:4: forfor smallsmall hatcherieshatcheries smallsmall hatcherieshatcheries
! 100% Hybrids 2 ! 100% Hybrids 3 ! ForFor hatcherieshatcheries usingusing ! IfIf freshwaterfreshwater hatcherieshatcheries freshwater,freshwater, 55--66 cmcm (SL)(SL) areare used,used, rearrear thethe fryfry inin fingerlingsfingerlings areare idealideal forfor elevatedelevated salinities.salinities. stocking.stocking.
! ConductConduct qualitativequalitative geneticsgenetics toto hastenhasten ! ForFor betterbetter growthgrowth ofof fry,fry, selectionselection processprocess throughthrough hatcherieshatcheries mustmust bebe inin biotechnology,biotechnology, elevatedelevated salinities,salinities, i.e.i.e. 1515-- 2828 pptppt.. – e.g. identification of gene responsible for salinity tolerance. ThankThank You!You!
Introduction Expected Outputs 1. As hybrids were backcrossed to their saline tolerant parent O. mossambicus, hybrids increased their salinity tolerance 2. Creation of a synthetic saline tolerant tilapia that can be bred and exploited in selection MethodologyMethodology Data collected
Initial weight before salinity test Daily mortality with their corresponding salinity Mean Salinity Tolerance (MST) Median Lethal Salinity (MLS) Optimum Salinity Tolerance (OST) Standard length (for experiment 2 only) Dominant behavior Clinical signs before mortality MethodologyMethodology
!!OreochromisOreochromisOreochromisOreochromis mossambicusmossambicusmossambicusmossambicus
!OriginalOriginal stocksstocks werewere collectedcollected inin thethe BWBW pondsponds aroundaround LingayenLingayen gulfgulf
!UndergoUndergo rotationalrotational crossingcrossing toto preventprevent furtherfurther inbreedinginbreeding
!NaturallyNaturally breedsbreeds inin hapashapas oror inin aq a ii m MethodologyMethodology
•OreochromisOreochromisOreochromis niloticusniloticusniloticus •Fry were from the Genetically Enhanced Tilapia (GET) of BFAR- NFFTRC, CLSU, Muñoz, N.E. MethodologyMethodology
ReciprocalReciprocalReciprocal Hybrids HybridsHybrids 1 11 Hybrid 1 (H1), hybridization between female O.mossambicus X male O. niloticus
Hybrid “1(H’1), hybridization between female O.niloticus X male O. mossambicus MethodologyMethodology
ReciprocalReciprocalReciprocal Hybrids Hybrids2Hybrids 22 Hybrid 2 (H2), hybridization between female Hybrid 1 X male O. mossambicus
Hybrid “2(H’2), hybridization between female O.mossambicus X male Hybrid ’1 MethodologyMethodology
ReciprocalReciprocalReciprocal Hybrids Hybrids3Hybrids 33 Hybrid 3 (H3), hybridization between female O. mossambicus X male Hybrid 2
Hybrid “3(H’3), hybridization between female Hybrid ‘2 X male O. mossambicus MethodologyMethodology Salinity Tolerance Test Acclimation Light (12L:12D) Feeding (ad libitum) H2O Quality (NO-3, PO-4, DO, pH, NH-3)
Reserved fish (to replenished in case mortality before the test) MethodologyMethodology SalinitySalinity LevelsLevels PreparationPreparation Artificially Prepared N1 V1 = N2 V2 Day ppt Day ppt Day ppt Day ppt Day ppt Day ppt
1 0 5 24 9 48 13 72 17 96 21 120
2 6 6 30 10 54 14 78 18 102 22 126
3 12 7 36 11 60 15 84 19 108
4 18 8 42 12 66 16 90 20 114 MethodologyMethodology MLSMLS DeterminationDetermination
•Plot the survival data Y = a + bx in a graph
100 •Obtain the regression equation from the 100% to 0% survival 50 50 = a + bx •Substitute the Y to 50 0 Salinity levels MLS •Compute MLS MethodologyMethodology OSTOST DeterminationDetermination
•Try different regression of the plateau until reaching 100 a significant one
50 •Test the significance of the regression plateau using stepwise regression 0 Salinity levels MethodologyMethodology OSTOST DeterminationDetermination
•Choose the Y = a1 + b1 regression line that is 100 significant
50 •The regression equation were marked as Regression line 1 0 Salinity levels MethodologyMethodology OSTOST DeterminationDetermination
Y = a2 + bx2 •Obtain the regression Y = a1 + b1 line 2 connecting to 100 the last value of the regression line 1 OST 50 a1 + bx1 = a2 + bx2 •Equate the two equation to obtain the value of X (OST) 0 Salinity levels MethodologyMethodology HeterosisHeterosis DeterminationDetermination
Average of Offspring - Average of Parents Heterosis = ------X 100 Average of Parents MethodologyMethodology Maternal/PaternalMaternal/Paternal InheritanceInheritance DeterminationDetermination
Salinity Tolerance Salinity Difference of Offspring with a Tolerance Reciprocal = mother that has a - Offspring with a Breeds high salinity father that has a tolerance high salinity tolerance MethodologyMethodology
InbreedingInbreeding ValuesValues DeterminationDetermination
Fx = Σ [ (0.5)N ]
F x = The inbreeding of an individual
Σ = The symbol of "sum of" or "add"
N = The numbers of individuals in a path that is determined by tracing a path from one parent back to the common ancestors and forward from the common ancestors to the other parent. If more than one ancestor exists, the term "(0.5)N ” is repeated for each common ancestor. If more than one path exists between the individual and a common ancestor, the term "(0.5)N " is repeated for each unique path.
F A = The inbreeding of a common ancestor. ResultsResults andand DiscussionsDiscussions SocialSocial BehaviorBehavior ofof TilapiaTilapia DuringDuring SalinitySalinity ToleranceTolerance TestTest •Recognition of Dominant Behavior •Guarding a territory •Guarding the source of food •Chasing and Driving other fish away from the territory. •Change in Coloration ResultsResults andand DiscussionsDiscussions Social Behavior of Tilapia During Salinity Tolerance Test •Observed Social Behavior •Hybrid 1 are docile at 30-36 ppt •Reciprocal Hybrid 2 and Reciprocal Hybrid 3 has 10-20% of the population are dominant until 48 ppt •At 98 ppt, H’1 still had dominant individual. one out of 40 (2.5%) ResultsResults andand DiscussionsDiscussions InbreedingInbreeding ValuesValues
O. moss A O, O. moss B O. moss C Collected niloticus Collected Collected from the From from the from the wild BFAR- wild wild •H1 has a zero inbreeding H1 M1 because it is a result of
M2 hybridization of H2 two different species H3
Figure x. Path diagram of the different hybrids ResultsResults andand DiscussionsDiscussions InbreedingInbreeding ValuesValues
O. moss A O, O. moss B O. moss C Collected niloticus Collected Collected from the From from the from the wild BFAR- wild wild •M1 assumed to have a zero H1 M1 inbreeding, because the
M2 parents are H2 collected in the wild H3
Figure x. Path diagram of the different hybrids ResultsResults andand DiscussionsDiscussions InbreedingInbreeding ValuesValues
O. moss A O, O. moss B O. moss C Collected niloticus Collected Collected from the From from the from the wild BFAR- wild wild •H2 has a zero inbreeding H1 M1 because the parents did not
M2 come from a H2 common ancestor H3
Figure x. Path diagram of the different hybrids ResultsResults andand DiscussionsDiscussions InbreedingInbreeding ValuesValues
O. moss A O, O. moss B O. moss C Collected niloticus Collected Collected from the From from the from the wild BFAR- wild wild •H3 has a theoretical H1 M1 computed inbreeding of
M2 H2 0.125, because the parents are both descendant H3 of M1
Figure x. Path diagram of the different hybrids ResultsResults andand DiscussionsDiscussions
FishFish BehaviorBehavior BeforeBefore MortalityMortality ResultsResults andand DiscussionsDiscussions FishFish behaviorbehavior BeforeBefore MortalityMortality
•Loss of dominance for the dominant fish •Sunken eyes and abdomen indicating its inability to osmoregulate •Coloration change from normal silver color to intensified body barring or to total black •Resting in tank bottom or gasping air ResultsResults andand DiscussionsDiscussions FishFish BehaviorBehavior BeforeBefore MortalityMortality •A minute before they die, some fish exhibit erratic swimming in a darting motion to an unpredicted direction •Some are to weak to counteract water movement •Contrary to other reports, there is no hyperplasia, swollen belly, septicemia and swollen eyes. ResultsResults andand DiscussionsDiscussions SizeSize andand SalinitySalinity ToleranceTolerance CorrelationCorrelation O.O. mossambicusmossambicus && O.O. niloticusniloticus
Size and salinity tolerance regression in O. mossambicus and O. niloticus
140 130 120 110 100 O. mossambicus 90 y = 1.0479x + 110.56 80 R2 = 0.0602; R = 0.2453; n=33; p=0.17ns 70 60 50
salinity tolerance (ppt) 40 O. niloticus 30 y = 0.4937x + 57.174 20 R2 = 0.0386; R = 0.1965; n=40; p=0.22ns 10 0 012345678910 size (cm, SL)
O. niloticus O. mossambicus Linear (O. niloticus) Linear (O. mossambicus) ResultsResults andand DiscussionsDiscussions SizeSize andand SalinitySalinity ToleranceTolerance CorrelationCorrelation HybridHybrid 11 && HybridHybrid ‘1‘1
Size and salinity tolerance regression in reciprocal hybrids 1
130 120 110 100 90 80 70 Hybrid 1 Hybrid "1 60 y = -2.1604x + 115.97 y = 5.7487x + 66.906 R2 = 0.4681; 50 R2 = 0.1556; R = 0.2322; R = 0.3945; salinity tolerance (ppt) n=14; p=0.34ns 40 n=21; p=0.08ns 30 20 10 0 012345678 size (cm, SL)
Hybrid 1 Hybrid '1 Linear (Hybrid '1) Linear (Hybrid 1) ResultsResults andand DiscussionsDiscussions SizeSize andand SalinitySalinity ToleranceTolerance CorrelationCorrelation HybridHybrid 22 && HybridHybrid ‘2‘2
Size and salinity tolerance regression in reciprocal hybrids 2
140 130 120 110 100
90 Hybrid 2 80 Hybrid "2 y = 0.6113x + 112.73 y = 6.2824x + 81.586 R2 = 0.1449; 70 R2 = 0.1456; R = 0.0004; 60 R = 0.3816; n=23; p=0.07ns n=27; p=0.049* 50 salinity tolerance (ppt) 40 30 20 10 0 012345678 size (cm, SL)
Hybrid 2 Hybrid "2 Linear (Hybrid "2) Linear (Hybrid 2) ResultsResults andand DiscussionsDiscussions SizeSize andand SalinitySalinity ToleranceTolerance CorrelationCorrelation HybridHybrid 33 && HybridHybrid ‘3‘3
Size and salinity tolerance regression in reciprocal hybrids 3
140 130 120 ) 110 100 90 Hybrid '3 Hybrid 3 80 y = 5.5904x + 84.705 y = -0.0491x + 114.03 R 2 = 0.1564 70 R2 = 0.0004; R= 0.3954 R = 0.01934; 60 n=27; p= 0.04* n=34; p=0.91ns 50 40
salinity where the fish dies (ppt fish the salinity where 30 20 10 0 012345678 size (cm, SL)
Hybrid 3 Hybrid "3 Linear (Hybrid 3) Linear (Hybrid "3)