Ornithology Lec 18: Reproductive System

What are the alleles that determine sex in birds?

ZZ= male

ZW= female

What is an adaptation for sex determination selection?

Selective release of one ova occurs in the female Seychelles Warbler. This allows them to release an ova with Z or W depending on current territory quality (they do cooperative breeding in which the females help raise young).

What is gynandromorphism?

When an organism displays characters of both males and females of their species due to cell division errors early in embryonic development.

What are the two different versions of gynandromorphism?

Mosaic gynandromorphism and bilateral gynandromorphism

What are the stages of egg formation in the female reproductive system?

1. Mature ovum in ovary, surrounded by yolk—> ovulated

2. Fertilized in infundibulum

3. Goes down the magnum (duct) where albumin is added

4. In the isthmus section soft shell is added

5. In the glandular section, covered in papillae, where lime is, the hard shell is added and pigment is added

6. Out the urovaginal junction

7. Out the cloaca

What birds have both ovaries (one is not ruptured)?

Raptors, kiwis

What are the components of the male reproductive system?

testes

vas defrens

What are some adaptations to ensure paternity?

1. copulate frequently after separation

2. cloacal protuberances in males for more sperm storage

3. larger testes and larger sperm stores

4. mate guarding

5. pecking female cloaca to remove other male’s sperm (ex: Dunnocks)

6. long cloacas in ducks (ex: Mallard)

Why have some species of ducks adapted long cloacas? Examples

Arms race between female vaginas and male elongated cloacas due to forced copulation. Restricts species that copulate together. Lymphatic swelling in the cloaca creates phallus structure, it does not contain the urethra.

ex: Mallard, Long tailed duck

What is the ranking of testes mass among different mating systems from most to least?

1. polyandry

2. colonial monogamy

3. solitary monogamy

4. lek promiscuity

result of decreasing sperm competition among these mating types and of diverging sperm morphologies

What is a fertilization adaptation among females to increase of clutch?

In Japanese quail sperm storage vesicles sperm can stay viable for days to months that can be used to fertilize different eggs.

What adaptations does post copulatory sexual selection promote in males?

Divergence of sperm morphology: midpiece length, flagellum length, total length

Influences: sperm ability to swim faster, live longer, displace other sperm form female storage tubules

How does sperm morphology change with female sperm storage tubules?

• increasing sperm storage tubule length—> increases sperm length

• increasing sperm storage tubule number—> decreases sperm length

longer sperm are selected for if there are few sperm storage tubules because sperm long enough to fill sperm storage tubules prevent access of other sperm

What is the increasing length of sperm primarily due to?

Disproportionately due to increase in midpiece size, because the midpiece is where ATP is stored (mitochondria is wrapped around the midpiece), increases energy

How does increased levels of of sperm competition affect sperm length?

There is an optimum length, so sperm length will stabilize as they approach the optimum in order to be competitive