male first, then female female, then male both at the same time hermaphrodites
TRANSCRIPT
•Male first, then female
•Female, then male•Both at the same time
Hermaphrodites
The gonad of the mangrove rivulus is half
ovary and half testis
Parrotfish
Parrotfish•Female when young
•Male as they get older
Black Sea Bass
Black Sea Bass•Switch sex back and forth quickly
•More often female as they get older
Clownfish
Clownfish• There is only one female in
each group• The female and the largest
male in group do all the spawning
• When the female dies, the largest male replaces her and the second largest male becomes the new head male
Explaining Nemo
• Nemo should have had a lot of uncles around
• When Nemo’s mom died..• His dad should have turned into his
mom and…• One of his “uncles” should have
turned into his dad
Why Hermaphrodites?
• Dominant male has a harem. He has spectacular reproductive success because he gets to fertilize the eggs from many females during a “spawning aggregation”.
• Other smaller males could not compete with the dominant male, so they would have no success at all.
• If they are female instead, then they have some success right now, and have a shot at being the dominant male when they get older and larger.
• Sneaky strategy…– Small males that look like females can sneak into
the spawning aggregation
Midshipman
Midshipman• Type 1 males: Grow slowly but
get big. Strong vocal system for courting
• Type 2 males: Mature quickly, small size, huge testes!
• Type 2s sneak in and fertilize the female that the Type 1 fish attracted
Other Sneakers• Bluegill
– Dash in, dash out– Female mimics
• Salmon– Remember the Jacks?
Chromosome Anatomy
1 2 3 4
Meiosis
1st polar bodyJUNKJUNK
Egg
2nd Polar Body
Egg
2nd PolarBody
Embryo
Embryo
<< >
Poeciliidae
The polar body staysSperm activates eggSperm DNA rejected
>>>>
<
<
>><<
XX
XX
GynogeneticFish
Irradiated sperm activate egg. Heat and pressure save polar body.Sperm DNA doesn’t participate
Triploid FishTriploid Fish•Heat and pressure prevent the loss of the polar body
•Fish has 3 sets of chromasomes
Hydraulic cylinder for
making triploid fish eggs
>><< >>
<<
>>
<<
XX
XX
XX
Making aTriploid
Heat and pressure prevent loss ofpolar body
Fish grows up with anExtra set of chromosomes
<<
DiploidRed Blood
Cell
TriploidRed Blood
Cell
Recognizing Triploids
CoulterCounter
X XX XX XXY XY XY
XX= FEMALE
Mendel Punnett
XX x XY
XXXXXYXY
Male and female fish produce young with a 50:50 sex ratio
Key Color = sex coded forby genes (genotype)
= sex that fish looks and acts like (phenotype)
XX x XY
XXXXXYXY
XXXXXYXY
Testosterone
Testosterone feed causes all of the tilapia to grow up looking and acting like males regardless of their DNA.
WZ x WW
WZWZWWWW
Sex determination in some tilapia species is opposite to that of the normal X, Y system. The WZ fish are the females.
WZ x XY
WXWYZXZY
Some Die:All survivorsare male
Crossing pure blood WZ fish with pure XY fish can produce all male young.
WZ x WW
WZWZWWWW
WWWW
WZWZ
WW x WW
WWWWWWWW
Sex reversed
Sex reversed WW fish can be used to produce all-male young.
All male fishAll male fish1. Testosterone2. WZ x XY hybrids3.Genetic “super” males
using sex reversed WW females
• HermaphroditesHermaphrodites– What does it mean?What does it mean?– What are the advantages?What are the advantages?– SneakersSneakers
• Meiosis and polar bodiesMeiosis and polar bodies• Gynogenetic fishGynogenetic fish• Triploid fishTriploid fish• Three ways to make all male tilapiaThree ways to make all male tilapia
– TestosteroneTestosterone– WZ x XY hybridsWZ x XY hybrids– Super malesSuper males