Reproduction Flashcards
Asexual Reproduction
- no distinct sex organs; no formation of gametes.
- Eg fission, budding
Sexual Reproduction
- requires meiosis to produce gametes (egg and sperm)
Monoecious
- both male and female sex cells produced in one organism.
Dioecious
- Male and female sex cells produced by 2 different organisms with specialized reproductive tissues.
Formation Of Cocoon
- sperm from each worm is transported to the seminal receptacles of the other along seminal grooves
- After mutual copulation, each worm secretes a mucus tube and chitinous band to form a cocoon.
- Cocoon passes forward and eggs, albumin, and sperm are poured into it.
- Fertilization occurs in cocoon; cocoon slides off head end and closes.
Syngamy
Fertilization of one gamete by another organism
Autogamy
Fertilization of one gamete by the same organism
Asexual Reproduction
- Genetically identical cells or individuals called clones.
Binary Fission
- A form of cell division in which the genome replicates and then the cell divides in two (eg bacteria).
Budding
- Is forming a bud or protrusion, on an organism that eventually breaks off to form a new organism that is smaller than its parent.
Fragmentation
- Splitting of one organism into pieces, each of which develops into a new individual.
Parthenogenesis
- females produce eggs that are not fertilized by males but divide by mitosis and develop into new individuals.
The Life Cycle Of Aurelia Aurita
- Gonads within gastric pouches
- Fertilization is internal therefore Sperm must enter the gastric pouch
- Zygote develops in water or oral arms
- Scyphistoma: hydra like and can form buds of other polyps (asexual reproduction)
- Strobilation: formation of repeating saucer like buds – Strobilla
- Buds that break free are called ephyra
Resting “Eggs”
▪Encapsulated embryos ▪Drought-resistent, hatching at specific cues
▪Survival through time and space (up to 40 years!)
Phylum Rotifera: Reproduction (Male)
- Dioecious
- Males are unknown in many species
- Instead, they reproduce via parthenogenesis (reproduction without fertilization of egg by male gamete
- females produce diploid eggs by mitosis (no meiosis!)
- each egg develops into a diploid female (2n)
- Class Bdelloidea: exclusive asexual parthenogenesis – males never discovered
- In this case, eggs are amictic (a = not; mictos = mixed)
Phylum Rotifera: Reproduction (Female)
- Females of some species produce two kinds of eggs (heterogony: alternates asexual/sexual reproduction)
- Eg. Class Monogonata (Most Rotifers)
Amitic Eggs
- Form diploid females by parthenogenesis.
Mictic Eggs
- Haploid eggs that have undergone meiosis.
Reproduction and Regeneration in Echinodermata
- Sexes separate in most species
- Fertilization is external
- Echinoderms can regenerate lost parts
- Cast off injured arms and regenerate new ones
- An arm can regenerate a new sea star if at least one-fifth of central disc is present
Asteroid Larvae: Metamorphosis
- Free-swimming larva, bipinnaria, has cilia arranged in bands
- Undergoes metamorphosis into a radial juvenile
- A/P axis (bilateral symmetry) is lost
- Arms and tube feet appear, animal detaches from substrate and becomes a young sea star
Brachiolaria
- larval arms and anterior sucker
Bird Reproduction
- Testes are very small until the approach of the breeding season
- enlarge 300x
- Males of most species lack a penis
- Mating involves bringing cloacal surfaces in contact
Fertilization (Birds)
- Fertilization takes place in the upper oviduct
- Special glands add albumin or egg white to the
egg as it passes down the oviduct - Farther down oviduct, the shell membrane, shell, and shell pigments are also secreted
Mating Systems (Birds)
Over 90% of bird species are monogamous
* Only mate with one partner each breeding season
* In a few species, such as swans and geese, partners are chosen for life
- In monogamous birds, constant attendance to the nest may require two parents
However, songbirds may be “unfaithful,” engaging in extra-pair copulations
- Nests of many of the sespecies may contain 30% of young with fathers other than attendant male
Newborn Birds
- Altricial birds are naked and helpless at birth and must be fed in the nest for a week or more
- Precocial birds are covered with down and run or swim as soon as they are hatched
How Does A Polyandry (Bird) Mate?
- One female mates with several males.
- Practiced by several shorebirds, including spotted sandpipers.
- Males incubate eggs and provide most parental care.
Reproduction In Sponges
- Can happen asexually and sexually.
- Monoecious-hermaphroditic- have male and female sex cells, though produced at different times.
- No gonads
-cells transform into sperm and enter canal of another sponge - eggs formed from archaeocytes
- Fertilization may take place in the mesohyl (ECM) to form a zygote and then larva.
- some sponges release egg and sperm into the water and the zygote forms in the water.
Sexual Reproduction In Sponges
- Fertilized egg to blastula to free-swimming larva.
Asexual Reproduction In Sponges
1) Fragmentation broken smaller piece forms new adult.
2) External or internal budding
Gemmule
- A dormant, encapsulated mass of archeocytes that waits until favorable conditions
- Each archaeocytes of the gemmule can give rise to a whole new sponge
Phylum Rotifera: Reproduction -
- Dioecious
- Males are unknown in many species
- Instead, they reproduce via parthenogenesis (reproduction without fertilization of egg by male gamete
- females produce diploid eggs by mitosis (no meiosis!)
- each egg develops into a diploid female (2n)
- Class Bdelloidea: exclusive asexual parthenogenesis – males never discovered
- In this case, eggs are amictic (a = not; mictos = mixed)
Nematode Reproduction
- Fertilization is internal
- sperm has no flagella in female reproductive tract sperm is ameboid and moves by pseudopods.
- Shelled zygotes / embryos are stored in uterus until deposition.
Male Reproductive System (Nematodes)
- Most male nematodes have only a single testis attached to the vas deferent which expands into a seminal vesicle which connects to the cloaca.
- Needle like mating spicules
- spicules holds the vulva of a female open
- ejaculatory muscles in the male overcome the hydrostatic pressure in the female
- sperm rapidly injected
Female Reproductive System (Nematode)
- consists of a pair of ovaries attached to an oviduct
- each oviduct becomes a tubular uterus, and the two uteri come together to form a vagina that opens to the outside through a genital pore.
