Diversity Of Reproductive Strategies Flashcards
Fertilisation inside the organisms body
Internal fertilisation
Fertilisation outside the organism’s body
External fertilisation
Type of fertilisation mainly occurring in aquatic environments
External fertilisation
Hermaphrodite organism
Having both male and female sex organs
Inseminated
Semen is deposited in the female body parts
Advantages of internal fertilisation
- Increased protection of sperm and eggs
- prevents waste of gametes
- specific mate selection (cf. sexual selection in evolution section )
Oviparous
- Eggs laid outside parents body
- protection by gelatinous mass or shell and membranes
- embryo develops inside egg -egg yolk feeds embryo -offspring hatches
Ovoviviparous
- Eggs kept inside parents body
- protection by soft shell and membranes
- embryo develops inside egg
- egg yolk feeds embryo
- offspring hatches inside body
- live young born from parent
Viviparous
- Eggs kept inside body
- protected by uterus and membranes
- embryo develops inside uterus
- mother feeds embryo through placenta and umbilical cord
- pregnancy followed by birth of offspring
- parental care follows e.g. Suckling
Amniotic eggs
- eggs that have a membrane called the amnion
- surrounds developing embryo of fertilised eggs
- found in reptiles, birds and mammals
Function of yolk sac in amniotic egg
Source of vitamins, minerals and fats for embryo
Function of chalaza in chicken egg
- Holds yolk and embryo in place
- Absorbs shock
The germinal disc in a bird egg
Small spot on the surface of the yolk from which the embryo develops
Chorion membrane
Encloses and protects the yolk sac and developing embryo
Function of air chamber in bird egg
- Helps with gaseous exchange
- protects against shock
Major source of protein for developing young in bird egg
Albumen (‘egg white’)
Precocial development
- Eggs often contain more yolk
- Born/hatched with eyes open
- Covered with fur/down
- Mobile in less than two days
- Follow parents, learning how to feed E.g. Ducks, buck
Altricial development
- Eggs contain less yolk
- Young hatch/born with eyes closed
- Little or no down/fur
- Unable to leave nest until independent
- Fed by parents until independent
- E.g. Pigeons, rodents
Parental care
- Parents caring for eggs or juveniles to ensure survival
- general decrease in energy used to produce vast numbers of offspring as parental care increases
