ABSTRACTS
Inbreeding
depression and heterosis in various quantitative traits of
the guppy, Poecilia reticulata
Aquaculture
Volume 220, Issues 1-4 , 14 April 2003, Pages 219-226
Motoki Nakadate, Takahito ShikanoCorresponding
Author Contact Information, E-mail The Corresponding Author
and Nobuhiko Taniguchi
Graduate School of Agricultural Science, Tohoku
University, 1-1 Tsutsumidori-amamiyamachi, Sendai, Miyagi
981-8555, Japan
Received 8 October 2001; revised 10 August
2002; accepted 12 August 2002. ; Available online 27 November
2002.
Abstract
The present
study examines the effects of inbreeding and crossing on various
quantitative traits in the guppy, Poecilia reticulata. Effects
of inbreeding and crossing were examined in six quantitative
traits; body length at birth, survival at day 120, undwarf
rate at day 120, body length at day 120, salinity tolerance
and high temperature tolerance. Full-sib matings revealed
that the amount of inbreeding depression varied from -1.0%
to 24.6% among the traits and a significant decrease in survival
at day 120 and salinity tolerance was observed. This result
indicates that inbreeding reduces the performance for some
of the quantitative traits but not all. On the other hand,
crosses between genetically different strains showed that
the amount of heterosis varied from -1.3% to 42.2% among the
six quantitative traits and a significant increase in survival
at day 120 and salinity tolerance was observed. The relationship
between the amount of inbreeding depression and heterosis
supports the theory that the phenomenon of heterosis is the
reverse of inbreeding depression, indicating that the traits
which have decreased by inbreeding can be recovered by means
of crossing.
Author
Keywords: Inbreeding depression; Heterosis; Quantitative trait;
Fitness; Guppy; Poecilia reticulata
Corresponding
Author Contact InformationCorresponding author. Present address:
Faculty of Biotechnology, Fukui Prefectural University, 1-1
Gakuen-cho, Obama, , Fukui 917-0003, , Japan. Tel.: +81-770-52-9603;
fax: +81-770-52-6003.
Relationships
between genetic variation measured by microsatellite DNA markers
and a fitness-related trait in the guppy (Poecilia reticulata)
Aquaculture
Volume 209, Issues 1-4 , 28 June 2002, Pages 77-90
Takahito
ShikanoCorresponding Author Contact Information, E-mail The
Corresponding Author and Nobuhiko Taniguchi
Graduate
School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-amamiyamachi,
Sendai, Miyagi 981-8555, Japan
Received
24 February 2001; revised 7 September 2001; accepted 10 September
2001. Available online 19 June 2002.
Abstract
We explored
two microsatellite-based variables, heterozygosity and a measure
of genomic diversity based on the mean squared distance between
microsatellite alleles within an individual (mean d2), in
relation to inbreeding depression for a fitness-related trait
using 925 individuals of 17 populations with various genetic
backgrounds, three wild populations, three domestic populations
and 11 domestic strains, in the guppy (Poecilia reticulata).
Mean heterozygosity observed at four microsatellite loci differed
among the populations and was higher in the wild populations
than in the domestic strains. Salinity tolerance, measured
by the survival time after transfer from fresh water to 35
ppt seawater, was used to examine the level of inbreeding
depression because the trait decreases linearly with an increase
in inbreeding coefficient and shows significant heterosis.
Among the 17 populations, salinity tolerance differed significantly
and was positively correlated with the mean heterozygosity.
This suggests that overall heterozygosity affects expression
of a fitness-related trait that shows inbreeding depression
and heterosis. Within each population, individual salinity
tolerance did not correlate with the individual level of multilocus
heterozygosity or with mean d2. These results indicate that
although the effect of the individual loci linked to loci
screened is too small to be detected by examining the individual
level of inbreeding depression within a population, the mean
heterozygosity of a set of microsatellite loci may be sensitive
enough to be a useful indicator for inbreeding depression
at the population level.
Author
Keywords: Heterozygosity; Heterosis; Inbreeding depression;
Microsatellite; Salinity tolerance; Guppy; Poecilia reticulata
Corresponding
Author Contact Information Corresponding author. Present address:
Faculty of Biotechnology, Fukui Prefectural University, 1-1
Gakuen-cho, Obama, Fukui 917-0003, Japan. Tel.: +81-770-52-6300;
fax: +81-770-52-6003; email: shikano@fpu.ac.jp
Using
microsatellite and RAPD markers to estimate the amount of
heterosis in various strain combinations in the guppy (Poecilia
reticulata) as a fish model
Aquaculture
Volume 204, Issues 3-4 , 11 February 2002, Pages 271-281
Takahito
ShikanoCorresponding Author Contact Information, E-mail The
Corresponding Author and Nobuhiko Taniguchi
Graduate
School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-amamiyamachi,
Sendai, Miyagi 981-8555, Japan
Available
online 1 November 2001.
Abstract
To explore
the use of microsatellite and random amplified polymorphic
DNA (RAPD) markers as a tool for estimating the amount of
heterosis in various strain combinations, diallel and reciprocal
crosses were performed among four laboratory strains in an
experimental fish, the guppy (Poecilia reticulata). Salinity
tolerance, measured as the survival time after transfer from
fresh water to 35 ppt seawater, was used as an index to measure
the amount of heterosis because this trait shows significant
heterosis and is strongly sensitive to its reverse, inbreeding
depression. The amount of heterosis, expressed by the ratio
between the means of the parents and their F1 hybrids, did
not differ between reciprocal crosses, but the mean values
varied from 1.4% to 45.9% among the strain combinations. Nei's
genetic distance, measured by microsatellite markers, differed
from 0.078 to 0.813 among the strains, and the dissimilarity
measured by RAPD markers differed from 0.125 to 0.320. The
amount of heterosis correlated with the Nei's genetic distance
(y=-0.351+53.350x, P<0.01) and also the dissimilarity value
(y=-19.832+187.091x, P<0.01). In the strain combinations
in which most of the dissimilarities among individuals were
higher than the mean dissimilarities within each strain (about
0.1), the amount of heterosis was positive in every pair.
In the strain combinations in which some of the dissimilarities
were below 0.1, on the other hand, the amount of heterosis
was positive in some pairs but negative in others. These results
indicate that the amount of heterosis depends on the level
of genetic diversity between the strains used for the cross,
suggesting that microsatellite and RAPD markers will be useful
for predicting the mean and variance of the amount of heterosis
in various strain combinations.
Author
Keywords: Heterosis; Inbreeding depression; Microsatellite;
RAPD; Heterozygosity; Salinity tolerance; Guppy; Poecilia
reticulata
Corresponding
Author Contact Information Corresponding author. Present address:
Faculty of Biotechnology, Fukui PrefecturalUniversity,
1-1 Gakuen-cho, Obama, Fukui 917-0003, Japan. Tel.: +81-770-52-6300;
fax: +81-770-52-6003; email: shikano@fpu.ac.jp
The
inheritance of heteroplasmy in guppies
Journal of Fish Biology May 2002, vol. 60, no. 5, pp. 1346-1350(5)
Taylor J.S. [1]; Breden F. [2]
[1] Department of Biology, University of Konstanz, Konstanz,
D-78457, Germany [2] Department of Biological Sciences, Simon
Fraser University, 8888 University Drive, Burnaby, BC, V5A
1S6, Canada
Abstract:
Guppies Poecilia reticulata from the Rio Grande, Trinidad
are heteroplasmic; individuals possess up to nine different-sized
mtDNA haplotypes. A PCR survey of mtDNA length variation that
included mothers and embryos suggests that a large number
of mitochondrial genomes (possibly within a much smaller number
of organelles) pass from one generation to the next. Copyright
2002 The Fisheries Society of the British Isles. Published
by Elsevier Science Ltd. All rights reserved.
Keywords: heteroplasmy; mtDNA; minisatellite;
inheritance; guppy; Poecilia reticulata
Effect
of inbreeding on salinity tolerance in the guppy (Poecilia
reticulata)
Aquaculture
Volume 202, Issues 1-2 , 19 October 2001, Pages 45-55
Takahito
ShikanoCorresponding Author Contact Information, E-mail The
Corresponding Author, Takashi Chiyokubo and Nobuhiko Taniguchi
Graduate
School of Agricultural Sciences, Tohoku University, 1-1 Tsutsumidori-amamiyamachi,
Sendai, Miyagi 981-8555, Japan
Received
29 April 2000; revised 16 December 2000; accepted 11 February
2001. Available online 10 October 2001.
Abstract
This experiment
was designed to study the relationship between different levels
of inbreeding and observed inbreeding depression for salinity
tolerance, one of the most important tolerances to environmental
conditions, in the guppy (Poecilia reticulata). Two generations
of full-sib mating and six generations of mating in the n=10
produced individuals with an expected level of inbreeding
coefficient of 0.375 and 0.265, respectively. A significant
decrease in the mean value of salinity tolerance, expressed
by survival time in 35-ppt seawater, was observed in both
the full-sib mated line and the closed line of n=10, indicating
inbreeding depression for salinity tolerance. The mean and
coefficient of variation (C.V.) of salinity tolerance decreased
linearly with the increase in inbreeding coefficient with
a rate of 9.1% and 10.1% per 10% increase in the inbreeding
coefficient, respectively. Analyses among seven lines of the
full-sib matings indicated that inbreeding caused the larger
reduction of the means observed in the lines having higher
salinity tolerance at the P generation and decreased both
deviations of the means among the lines and C.V. within each
line. The linear decrease in salinity tolerance with an increase
in inbreeding coefficient suggests that inbreeding depression
for salinity tolerance results from additive combination among
the loci responsible for inbreeding depression.
Author
Keywords: Inbreeding depression; Inbreeding coefficient; Full-sib
mating; Effective population size; Salinity tolerance; Guppy;
Poecilia reticulata
Effect
of temperature and dietary Image-carnitine supplementation
on reproductive performance of female guppy (Poecilia reticulata)
Aquaculture
Volume 199, Issues 3-4 , 1 August 2001, Pages 323-332
Ron Dzikowski,
Gideon Hulata, Ilan Karplus and Sheenan HarpazCorresponding
Author Contact Information, E-mail The Corresponding Author
Department
of Aquaculture, Agricultural Research Organization, The Volcani
Center, P.O. Box 6, Bet Dagan 50250, Israel
Received
2 July 2000; revised 29 January 2001; accepted 29 January
2001. Available online 25 July 2001.
Abstract
The goals
of this study were (1) to determine the optimal temperature
for fry production by female guppy of two commercial strains
(lyre tail and red cobra) and (2) to investigate whether dietary
Image-carnitine supplementation could help in alleviating
reproductive problems associated with exposure to temperature
stress. For the first goal, females were tested at temperatures
ranging from 20°C to 32°C. Temperature was shown to
have a significant effect on mean brood interval in both strains,
but an effect on brood size was found only in red cobra. Best
fry production was achieved at 25–27°C. A water
temperature of 32°C caused increased female and fry mortality,
degeneration of ovaries and reduced brood size. All surviving
offspring at this temperature differentiated into males, but
suffered from morphological abnormalities. For the second
goal, females were tested at the optimal rearing temperature
(26°C), and under high-temperature stress (32°C) and
low-temperature stress (23°C). The parameters examined
were brood size, brood interval and their quotient, and brood
size/brood interval, which is the reproduction potential of
the fish. Overall, Image-carnitine supplementation at a dosage
of 1100 mg/kg food, had no significant effect on brood interval
or fry production efficiency.
Author
Keywords: Image-Carnitine; Temperature; Reproduction; Poecilia
reticulata; Guppy
The
relationship between allozyme heterozygosity and salinity
tolerance in wild and domestic populations of the guppy (Poecilia
reticulata)
Takahito
ShikanoCorresponding Author Contact Information, E-mail The
Corresponding Author, Takashi Chiyokubo, Motoki Nakadate and
Yoshihisa Fujio
Faculty
of Agriculture, Tohoku University, 1-1 Tsutsumidori-amamiyamachi,
Sendai, Miyagi 981-8555, Japan
Accepted
6 October 1999. Available online 30 March 2000.
Abstract
The present
study examines the relationships between heterozygosity and
a fitness-related trait that shows heterosis in six wild populations
and 14 domestic strains of the guppy (Poecilia reticulata).
Mean heterozygosity, estimated from five polymorphic and 23
monomorphic allozyme loci, and salinity tolerance, measured
as the mean survival time after transfer from fresh water
to 35 ppt seawater, were greater in the wild populations than
in the domestic strains. The result suggested that inbreeding
has decreased both the mean heterozygosity and the salinity
tolerance in the domestic strains. Although the individual
level of multilocus heterozygosity and allozyme genotype did
not correlate with the individual salinity tolerance within
each population, a positive correlation (P<0.01) was observed
between the mean heterozygosity and the salinity tolerance
among the wild populations and the domestic strains. These
results suggest that overall heterozygosity may be important
in determining a fitness-related trait, but that the effect
of the individual loci screened is too small to be detected
by examining a limited number of one-locus genotypes. However,
the mean heterozygosity of a set of loci may be sensitive
enough to be a useful indicator for inbreeding depression
of the fitness-related trait in a population.
Author
Keywords: Heterozygosity; Heterosis; Inbreeding depression;
Population genetics; Salinity tolerance; Guppy; Poecilia reticulata
Production
of a YY female guppy, Poecilia reticulata, by endocrine sex
reversal and progeny testing
Aquaculture
Volume 118, Issues 3-4 , 15 December 1993, Pages 183-189
Soosamma
Kavumpuratha, Corresponding Author Contact Information and
T. J. Pandianb
a Department
of Zoology, Fatima Mata National College, Kollam, Kerala,
India
b School of Biological Sciences, Madurai Kamaraj University,
Madurai, Tamil Nadu, India
Accepted
14 July 1993. ; Available online 3 October 2003.
Abstract
A YY-female
Poecilia reticulata was produced by endocrine sex reversal
followed by progeny testing. Heterogametic females (XY) produced
by endocrine sex reversal were mated with normal males (XY)
and subsequently treated with an estrogen-supplemented diet,
5–10 days prior to parturition. Progenies obtained from
these fish were individually mated with sex-reversed males
(XX) to identify their genotype. A single female was identified
to have the YY-genotype, and produced only males when mated
with a sex-reversed male (XX).
Corresponding
Author Contact InformationCorresponding author. Correspondence
to: S. Kavumpurath, Department of Zoology, Fatima Mata National
College, , Kollam 691001, Kerala, , India.
