http://watchingtheworldwakeup.blogspot.com/2008/08/unbearable-lightness-ofaspen-part-1.html
Sciurus carolinensis
Gray squirrels
• Reproduce sexually
• Diploid organisms with
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haploid gametes.
Reproduce Dec-Feb
and June-Aug
Litters of 2-4 pups
Pregnancy lasts 40-44
days
Pups are weaned by
10-12 weeks
General squirrel info
• Squirrels will chase each other to establish
dominance (spiral chasing around tree), play, and as
a type of mating ritual (slower paced).
• Both male and female squirrels are polygynandrous
(promiscuous), although once ejaculation occurs, a
mucus plug forms over the vagina preventing further
mating.
• The squirrel population has gotten so large and has
led to damage of trees. As a result,
immunocontraception is being tested as a
mechanism of population control.
Asclepias syriaca (Milkweed):
The Basics of their Reproduction
*Part of the kingdom Plantae and reproduce sexually
by pollinating the seeds held within a pod (see
right)
*Follow a diploid→haploid→diploid pattern
(plant→seeds/pollen→fertilized zygote)
*The number and quality of flowers in an
inflorescence (complete flower head of a plant) is
directly correlated to the number of viable seedfilled pods (up to 30 flowers)
*Self fertilization in possible for milkweed, as is
typical cross breeding between two separate
milkweed plants
* Because of the pods, milkweed utilize a “high-cost,
low-risk” manner of reproduction-- see next slide
The High-Cost, Low-Risk Phenomenon
*All seeds in a milkweed are stored together in pods, each containing up to 100 seeds!
*Why “high-cost”?
If the pod is damaged or for any reason cannot be fertilized, a loss of not just one but up to 100 seeds occurs.
*Why “low-risk”?
The stability and structure of the pod prevents loss in most circumstances.
*The benefits of the pod outweigh the risk; the development of this is thought to be an evolutionary adaptation
to increase sexual fitness.
Sources Used:
Wilson, Mary, Rathcke, Beverly. 1974. Adaptive Design of the Floral Display in Asclepias syriaca L. American Midland Naturalist. Vol. 92, p.48.
Kilps et al. 2004. https://bioweb.uwlax.edu/bio203/s2013/baumann_brea/reproduction.htm.
ANAX JUNIUS-COMMON
GREEN DARNER
 One of the most common
dragonflies in North America
 Widespread
 Found from Alaska to southern
parts of Central America
 Distinctive differences between
males and females
 Males have a bright blue abdomen
 Females have a reddish brown
abdomen
http://www.arkive.org/common-green-darner/anax-junius/
http://animaldiversity.ummz.umich.edu/accounts/Anax_junius/#physical_description
http://www.nps.gov/miss/naturescience/greendarner.htm
 Residential and Migratory
 Home for early summer
 South for the winter!
 Copulation on vegetation
 Male grabs female by top of the
head or prothorax
 “Wheel” position
 Laying the eggs
 Flying in tandem
 Jealous males
 Suitable aquatic environments
 Multiple batches of eggs
HONEY BEE (Apis mellifera)
 All bees are able to reproduce BUT this “job” in the
hive falls to the queen bee (only female with fully
developed ovaries)

Up to 2,000 eggs a day and up to 1,000,000 eggs in her
lifetime
 Mates with males, called drones, midair
 Can mate with a number of different males
 Sometimes copulation between honey bees can be audible to
the human ear as a popping noise because of the force of the
ejaculation
 Male dies after copulation
 Fertilized eggs will develop into female bees while
reared, unfertilized eggs will turn into male bees
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Female bees are diploid
Male bees are haploid
 Larvae hatch in about
3-4 days and are then fed
by worker bees
 Different castes of bees
emerge at different times

http://climatekids.nasa.gov/bees/
Queens: 15-16 days, Workers: 21 days, Drones: 24 days
Daphnia“Water Fleas”
• Order Cladocera- water
crustaceans
• Live in fresh water
• Found almost anywhere that
open fresh water is found
• Over 150 species
documented in the United
States
• Have one compound eye
• Eat phytoplankton and algae
• Very prolific due to their
ability to reproduce by cyclic
parthenogenesis
Anatomy of female Daphnia (greatly magnified); diagrammatic. B, brain;
BC, brood chamber; C, digestive caecum; CE, compound eye; F, fornix; FA,
first antenna (antennule); H, heart; INT, intestine; O, ocellus; OV, ovary; R,
rostrum or beak; SG, shell gland. (Fig 1 was greatly modified from Storch,
1925.)
What is Parthenogenesis???
• Parthenogenesis
– A form of asexual
reproduction
– Offspring are exact
replicas, or “clones”
– Embryo develops from an
unfertilized egg and
directly into an adult
– Stable environments
perpetuate successful
genotypes
• Application to Daphnia
– Evolutionarily advantageous to
benefit during “favorable”
conditions
• Depends on temperature and
availability of food
• Late spring, summer, and early
autumn
• Only females are produced at
this time
– Females reproduce as early as
4 days old, and birth 10 live
young as often as every 3 days
– Can produce up to 25 broods
in on lifetime
Cyclic Parthenogenesis
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Reproduction by parthenogenesisonly in favorable conditions to
produce generations of diploid
females
In unfavorable conditions, some
ovum develop into haploid males
Females produce haploid eggs that
must be fertilized by the haploid
males (sexual reproductionincreases variety), and are then
shed from the female in carapace
cases known as an ephippium
The ephippium embryos are in
suspended animation and can
survive freezing and drought
conditions
Once conditions improve, live
young emerge from the ephippium
and the male sex dies out entirely
until environmental stress returns
http://bioweb.uwlax.edu/bio203/2010/carroll_chri/r
eproduction.htm
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Grape Phylloxera
Insect that reproduces sexually and asexually
Two different kinds of females: winged and wingless
How it works:
In spring, a wingless female hatches from a fertilized
egg that had been laid on the stem of a grape vine.
(Produced sexually)
She migrates to a leaf where she produces a gall and
grows to maturity in about 15 days.
She fills the gall with eggs and dies.
Nymphs that hatch from these eggs escape from the
gall, and wander to new leaves where they in turn
produce galls and eggs.
This may create 6 or 7 generations during the
summer.
In the fall, nymphs migrate to the roots where they
hibernate through the winter.
http://www2.ca.uky.edu/entomology/entfacts/ef222.asp
http://www.annualreviews.org/doi/abs/10.1146/annurev.ento.46.1.387
• The following spring they become active again and produce root galls.
• Wingless females may cycle indefinitely on the roots year after year.
• In late summer and fall, some of the root inhabiting females lay eggs
that develop into winged females.
• These winged females migrate from the roots to the stems where they
lay eggs of two different sizes.
• The smaller eggs develop into males and the larger eggs into females.
• Mating occurs and the female lays a single fertilized egg that winters
on the grape stem.
• It is this egg that gives rise to leaf inhabiting generations.
• It is important to note that phylloxera cycle continuously as root
inhabitants.
• So while they can cycle continuously on the
roots without leaf forms occurring, leaf
inhabiting forms do not occur without
the root form also occurring.
http://www.ncbi.nlm.nih.gov/books/NBK9980/
• Haploid spores grow under leaves
• Spores drop to ground; grow into
heart-shaped gametophytes
• Gametes develop on gametophytes
• Gametes are fertilized (becoming
diploid); grow after 2-6 months into
the structure we typically think of as
the fern plant (which is the
sporophyte)
• Under the leaves of the diploid
sporophyte grow haploid spores,
and cycle repeats
• Ferns are either hermaphroditic or of a
single sex (can be affected by pheromones)
• Reproduce via “selfing” or “crossing” means
(depending on if the gametes come from
gametophytes of the same or different
sporophytes)
• “Selfing” fertilization can be
intergametophytic (gametes come from
different gametophytes) or
intragametophytic (gametes come from the
same gametophyte)
• Water is required for fertilization
• In a 10-yr experiment with the three types
of breeding, intergametophytic crossing
progeny showed the lowest adult mortality
rates (with greatest heterozygosity of
offspring); this type of reproduction is most
common
Schneller, Johann Jakob. "Biosystematic investigations on the lady fern (Athyrium filix-femina)." Plant Systematics and Evolution 132.4 (1979): 255-277.
Schneller, Johann Jakob, and Rolf Holderegger. "Vigor and survival of inbred and outbred progeny of Athyrium filix-femina." International Journal of Plant Sciences (1997): 79-82.
Schneller, J. J. "Spore bank, dark germination and gender determination in Athyrium and Dryopteris. Results and implications for population biology of pteridophyta." Botanica
helvetica 98.1 (1988): 77-86.
Harvestmen: Daddy Long-legs
Arachnid/Opillione/Phalangiidae
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Live up to 1 year
Sexual Reproduction
Two sexes: male has penis, female has ovipositor
Mating: nuptial giftf; face-to-face; male can be rejected; up to three
minutes
• Oviposition: can take up to five hours; 60-210 eggs; mother guards for up
to two months, and father can help guard too
• Hatchlings: incomplete metamorphosis with several molting cycles
• U of Maryland Harvestman Webpage