Reproduction

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Reproduction
Alexis Draper Lorraine Thompson Tomasita Jallad
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Sexual Reproduction
two individuals produce offspring that have
genetic characteristics from both parents
introduces new gene combinations in a
population fusion of two distinct gametes to
form a zygote
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Types of Fertilization
Two mechanisms by which fertilization can take
place 1. External the eggs are
fertilized outside of the body 2. Internal
the eggs are fertilized within the female
reproductive tract
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Patterns and Cycles
NOT a continuous activity occur during
certain parts of the year so that offspring can
typically be born under favorable conditions
allow organisms to manage the relative
expenditure of energy for reproduction and
maximize the chances of survival for the
resulting offspring
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Asexual Reproduction
one individual produces offspring that are
genetically identical to itself
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Budding
an offspring grows out of the body of the parent
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Gemmules
A parent releases a specialized mass of cells
that can develop into an offspring
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Fragmentation
the body of the parent breaks into distinct
pieces, each of which can produce an offspring
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if a piece of a parent is detached, it can grow
and develop into a completely new individual
Regeneration
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the ovum develops into a new individual without
fertilization
Parthenogenesis
unfertilized eggs give rise to the male drones
and the fertilized eggs to the female workers and
queens
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Parthenogenesis
common at higher latitudes common in harsher
environments one or many stimuli that trigger
sexual reproduction critical population size,
crowding, poor temperatures
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Aphids
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Parthenogenesis in Aphids

• Cyclical parthenogenesis
• Alternate between sexual and asexual phases
  primarily asexual
• males of some species are rarely seen eggs of
  males unknown
• Viviparity
• Giving birth to living offspring that develop and
  hatch within the mothers body.
• may reproduce 2 3 young daily
• In warm conditions, females may mature in 7 10
  days
• population can double every 7 days

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Parthenogenesis in Aphids

• Viviparity results in a shortening of generation
  time, overlapping generations, increased
  reproductive potential increased rate of
  development of resistance to insecticides.

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Parthenogenesis in Aphids

• Host alternation is common
• Aphids use one plant as the primary host for
  reproduction another plant as a secondary
  host for parthenogenic reproduction.
• In Aphidinae, migrants returning to the primary
  host are winged males and winged parthenogenic
  females which produce egg-laying sexual females.
• Later on, winged parthenogenic females return to
  the secondary host (herbaceous plant).
• Both parthenogenesis and host alternation have
  enables aphids to exploit their food plants (such
  as agricultural crops).

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Aphid Life cycle
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Water Fleas
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Water Fleas

• occurs during most of the summer
• produce only female offspring from eggs
• the young mature to a well-developed stage
  within the brood chamber of the parent
• sustained by their egg yolk, and then by a
  secretion from the inside of the brood chamber
• Towards autumn, males are produced which
  fertilize special eggs, capable of surviving
  winter
• hatch the following spring into females, which
  will continue the parthenogenic cycle.

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Copepods
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Copepods

• reproduction requires copulation
• Females are usually more abundant than males
• During copulation, males grasp females using
  their antennae and (depending on the species)
  with a modified pair of thoracic appendages
• The male transfers a sperm-containing package
  called a spermatophore to the female using its
  thoracic appendage
• The spermatophore attaches to the female at the
  genital opening where it will be used to
  fertilize the eggs
• In some species, eggs are shed singly, while many
  free-living species retain their eggs within
  attached ovisacs until hatching

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Sea hares
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Hermaphroditic Sea Hares

• have both male and female reproductive organs
• Chain mating
• Each individual is having sex with the individual
  behind as well as the proceeding one
• Act both as a male and female
• The first individual is acting solely as a
  female
• The end of the chain is only taking use of its
  male reproduction organs

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Sponges
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Sponges Asexual / Sexual

• can reproduce either way
• different kinds of sponges get their eggs
  fertilized in different ways
• Inside the body wall of the parent sponge of
  some species
• Eggs are squirted into the surrounding water for
  fertilization in other species

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Sponges sexual reproduction

• some cells in the jelly-like layer can be eggs
  or sperm
• fusion of sperm and eggs produce zygotes
• fertilization occurs in the mesenchyme and
  zygotes develop into free swimming immature
  organisms, which eventually attach to the ocean
  bottom and develop into new sponges
• some species are hermaphrodites, producing both
  egg and sperm
• sperm are frequently broadcast into the water
  column
• sperm are created concentrated and sent out the
  excurrent openings, sometimes in masses so dense
  that the sponges appear to be smoking

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Sponges asexual reproduction

• a new sponge begins to grow from the parent and
  then it breaks away
• sometimes a piece of the parent may break away
  and then develop into a new sponge.
• some produce branches the develop into new
  sponges
• others asexually produce flagellated embryos
• they swim away, and they later attach to things
  to form new sponges

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Sponges asexual reproduction

• Gemmules
• groups of cells that have become enclosed by a
  tough outer covering
• they can survive long periods of time in
  freezing and extremely hot weather conditions.
• when the conditions change, such as after a
  drought or winter, the cells leave the gemmule,
  then they come together to form a new sponges

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Jellyfish
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Jellyfish

• there are a variety of reproductive strategies
  in the phylum Cnidaria, but most follow a basic
  scheme.
• the adult form is a medusae (jellyfish) most of
  which are dioecious, meaning that each animal is
  either a male or female
• a group of animals releases sperm or eggs, which
  may mix in the water column and become
  fertilized, or, in the case of the moon jelly
  (Aurelia) the eggs become lodged in pits on the
  oral arm, which form a temporary brood chamber
  where fertilization takes place.

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Jellyfish

• reproduction involves several different stages
• in the adult, or medusa, stage of a jellyfish,
  they can reproduce sexually by releasing sperm
  and eggs into the water, forming a planula.
• in the larval stage, the planula hooks on the
  bottom of a smooth rock or other structure and
  grows into another stage of jellyfish life, the
  polyp which resembles a miniature sea anemone.
• during this stage, which can last for several
  months or years, asexual reproduction occurs
• the polyps clone themselves and bud, or
  strobilate, into another stage of jellyfish life,
  called ephydra. It is this form that grows into
  the adult medusa jellyfish.

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Echinoderms
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Echinoderms Asexual Sexual

• asexual reproduction usually involves the
  division of the body into two or more parts
  (fission) and the reproduction of missing body
  parts
• successful fission and regeneration require a
  body wall that can be torn and a ability to seal
  resultant wounds
• also requires that certain body parts be present
  in the lost pieces.
• for example, many sea stars can regenerate a
  lost portion only if some part of the central
  disk is present.
• sexual reproduction involves the external
  fertilization of eggs by spermatozoa
• the fertilized eggs develop into planktonic
  larvae
• the larvae typically go through two stages
  bipinnaria and brachiolaria

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Squid
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Squid

• cephalopods exhibit slight sexual dimorphism
• The males are smaller than females
• The males have lappets, which are left over
  juvenile characteristics that aid in positioning
  the male during copulation
• The male places a ball of sperm into the females
  mantle cavity, where her eggs are fertilized
• There is no larval stage in the cephalopoda life
  cycle because the adults are mobile, and the
  whole purpose of the larval stage is to move the
  young away from the adults for creatures that are
  immobile

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Mating is trigger for death

• Argiope aurantia
• Palps inserted
• Male becomes a mating plug
• Female eats corpse

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Wolf Spiders

• Immature female meets a male
• Female remembers his appearance
• Only mates with familiar males
• They were the first invertebrates to show this
  long-term memory

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Periodical Cicadaes

• Species sing at different times
• In evening all species sing
• 17 year life cycle

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Corals

• Use sexual and asexual reproduction
• Grow .8 inches/year
• Budding intratentacular

Extra-tentacular
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Corals

• Fragmentation
• Ex Acropora cervicornis
• Constant addition stabilizes reef
• Incredible ability to grow from broken-off pieces

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Mass Spawn

• Ex Montastraea Acropora
• In 24 hrs. all release gametes
• Released in sack
• Some brood larvae

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Other Asexual Reproducers

• Worms
• Sea squirts

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Parthenogenesis
Honey Bees

• Unfertilized egg-male
• Fertilized egg-female
• Male only purpose to mate with a queen
• Males die upon mating or are expelled in winter
• New queen mates with 7 males in 13 min.
• She stores sperm for the rest of her life

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Honey Bees
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Rotifers

• Some species only female that produce daughters
• Other species produce 2 kinds of eggs
• Sexual dimorphism female and degenerate male

rotifer birth
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Oldest Penis Found

• 400 million yrs. Old
• Daddy-longlegs
• Lived in hot springs