Life cycles animals lecture 5 Flashcards
What does it mean for a species to be gonochoric?
In gonochoric species, individuals will sexually mature as either male OR female, with only one type of gametes maturing during their lifespan.
What is a defining characteristic of hermaphroditic species?
In hermaphroditic species, an individual can mature as both male AND female, maturing both sperm and oocytes during its lifetime.
Does having a gonad with both male and female tissue necessarily mean a species is hermaphroditic?
No, a species is considered hermaphroditic only if both types of gametes mature during the individual’s lifetime.
What is simultaneous hermaphroditism?
In simultaneous hermaphroditism, both types of gametes mature at the same time.
What is sequential hermaphroditism?
In sequential hermaphroditism, an individual matures one type of gametes first and then the other at different times.
Define protogynous hermaphroditism
Protogynous hermaphroditism is when an individual matures first as female (producing oocytes) and then changes to male (producing sperm).
Define protandrous hermaphroditism
Protandrous hermaphroditism is when an individual matures first as male (producing sperm) and then changes to female (producing oocytes).
What are the indicators of protogynous hermaphroditism?
Indicators include a sex ratio biased towards females, different size frequency distributions (females smaller than males), and different ages (females younger than males).
What are the indicators of protandrous hermaphroditism?
Indicators include a sex ratio biased towards males, different size frequency distributions (males smaller than females), and different ages (males younger than females).
What is the difference between monandry and diandry in protogynous hermaphroditism?
In monandry, males appear only after sex-change, whereas in diandry, some individuals may mature directly as males while others become males after sex-change.
What can complicate the identification of sequential hermaphroditism based on indicators?
Factors such as different growth rates, survival rates, habitat use, and catchability between sexes can influence size and sex ratios, complicating identification.
How does gonad morphology aid in identifying sequential hermaphroditism?
Observing regression and development of gonadal tissue during sex change is key, but it varies among families and can be more or less evident.
Describe the gonad characteristics in immature Sparidae
- Immature Sparidae gonads have both male and female tissue, with one part developing at maturity and the other regressing if the species changes sex.
- Regression and development of the two parts when the individual is changing sex represents a key element.
How does fishery impact specie with sequential hermaphroditism in general?
In general, fishery is selective towards large individuals. Therefore, in specie with sequential hermaphroditism fishery will catch more the largest sex:
How does fishery impact protogynous species?
- Fishery tends to remove more large males, skewing the sex ratio towards females.
- As a consequence, sex-ratio will result particularly skewed towards the smallest sex (females)
