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

Female when young Male as they get older

Black Sea Bass

Switch sex back and forth quickly More often female as they get older

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

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 1234

Meiosis

1 st polar body JUNK

Egg 2 nd Polar Body

Egg 2 nd Polar Body Embryo

< < > > Poeciliidae The polar body stays Sperm activates egg Sperm DNA rejected >> > > < <

> < < X X X X Gynogenetic Fish Irradiated sperm activate egg. Heat and pressure save polar body. Sperm DNA doesn’t participate

Triploid Fish Heat and pressure prevent the loss of the polar body Fish has 3 sets of chromasomes

Hydraulic cylinder for making triploid fish eggs

> < < > > < < > > < < X X X X X X Making a Triploid Heat and pressure prevent loss of polar body Fish grows up with an Extra set of chromosomes < <

Diploid Red Blood Cell Triploid Red Blood Cell Recognizing Triploids

Coulter Counter

XX XXX YXYXYXYXY XX= FEMALE MendelPunnett

XX x XY XX XY Male and female fish produce young with a 50:50 sex ratio Key Color = sex coded for by genes (genotype) = sex that fish looks and acts like (phenotype)

XX x XY XX XY XX XY Testosterone Testosterone feed causes all of the tilapia to grow up looking and acting like males regardless of their DNA.

WZ x WW WZ WW 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 WX WY ZX ZY Some Die: All survivors are male Crossing pure blood WZ fish with pure XY fish can produce all male young.

WZ x WW WZ WW WZ

WW x WW WW Sex reversed Sex reversed WW fish can be used to produce all-male young.

All male fish 1. Testosterone 2. WZ x XY hybrids 3.Genetic “super” males using sex reversed WW females

HermaphroditesHermaphrodites –What does it mean? –What are the advantages? –Sneakers 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 –Testosterone –WZ x XY hybrids –Super males