Environmental Effect on Development. Flashcards
Can the environment can play a role in determining the phenotype of an organism?
Yes.
What is phenotypic plasticity?
The ability of an organism to take information from the environment and change as a result.
Phenotypic plasticity can result in what kind of changes?
Developmental, i.e. structure or function.
Or behavioural changes.
What is developmental plasticity?
When phenotypic plasticity occurs in the developmental or larval stages of an organism.
What is polyphenism?
A discontinuous phenotype that results due to influences from the environment.
What is diet induced polyphenism?
Polyphenism that arises due to what the organism eats during development.
What is predatory induced polyphenism?
This occurs when predators in the environment cause phenotypic changes.
What influences predatory induced polyphenism?
Because predators release hormones called kairomones.
These are detected by individuals and will cause a change in phenotype.
Why will organisms change their phenotypein the presence of a phenotype?
These changes are designed to increase survival of the prey animal.
How can changes in developmental timing be induced?
Due to the presence of a predator.
What is temperature dependent sex determination?
When the sex of an organism is determined by the temperature of the embryo at certain moments during development.
What are the phenotypic differences between worker bees and queen bees?
Worker honey bees tend to be very small.
The queen is much larger in size than the worker bee.s
Why is the queen larger than the worker bees?
She has ovaries in her body so that she can keep reproducing.
Which bees are capable of reproducing?
The queen bees are the only bees that can reproduce.
How do the phenotypic differences between the queen bee and the worker bees arise?
Because of what they are fed as larvae.
What are queen bees fed as larvae?
Royal jelly.
What do worker bees get fed as larvae?
A protein called casein that does not produce the same amount of growth as royal jelly.
What protein does royal jelly contain?
Royalactin.
How does royalactin influence growth?
It binds to EGF receptors (epidermal growth factors) in the developing larvae which stimulates cell growth and development.
How does royalactin stimulate fertility?
It stimulates the juvenile hormone which allows the queen bee to become sexually reproductive.
What is the species name of the caterpillar that has diet induced polyphenism?
Nemoria arizonaria.
What does the diet induced polyphenism in the caterpillar help it to do?
Be camouflaged from predators.
Caterpillars that are born in spring eat what?
Oak flowers (catkins).
Caterpillars that are born in summer eat what?
Oak leaves.
What is the diet that induces a larger size in the caterpillars?
Oak flowers (catkins).
Caterpillars that eat catkins will look like what?
A fuzzy coating with brown dots that mimics catkins.
Caterpillars that eat oak leaves will develop what?
Very small twigs.
What is it between the caterpillars diet of catkins and oak leaves that causes the change in phenotype?
The tannins in the oak leaves.
Will all dung beetles develop a horn on the head?
No.
What will cause the development of a horn on the head of a dung beetle?
The quality of the dung that the dung beetle was provided for the larvae.
What kind of dung will cause the development on the head of a dung beetle?
Good quality dung.
Why does good quality dung cause the horn to develop?
The triggering of the juvenile hormone once the larvae reach a certain size.
How does poor quality dung influence the phenotype of a dung beetle?
There won’t be as much growth and the dung beetle will not develop a horn.
The presence or absence of a horn will affect what about an adult dung beetle?
Its behaviour.
Can horned males or non horned males dig holes?
Non horned males.
When a horned male mates with a female, what will he do?
The female will dig a tunnel under a dung heap and will lay the eggs in this tunnel.
Horned males will guard the tunnel and defend the tunnel against other males.
What is another name for hornless males?
Sneaker males.
How do hornless males mate with females in a tunnel?
They will dig a tunnel past the guarding male and link up with the female.
How many matings are estimated to be done by sneaker males?
50%.
What affects the phenotype of the desert locust?
Whether they have hatched during a dry period or a wet period.
If locust eggs hatch during a period of drought, what phenotype will the offspring have?
Solitary locusts.
What is the phenotype of a solitary locust?
Green in colour, small and has under developed wings.
If the locusts hatch during a wet period, what will the phenotype be?
They are said to have a gregarious phenotype.
What is the gregarious phenotype?
Brown in colour, larger and they will develop long wings.
Which phenotype of locusts will release a pheromone that causes them to swarm?
Gregarious locusts.
What causes the differences between the gregarious phenotype and the solitary phenotype?
If the soil is moist, then it will be easier for the females to lay their eggs.
There is more food for the juveniles, so the density of eggs is very high.
What do the juvenile gregarious locusts do when they hatch?
They will bump into each other which stimulates the phenotypic changes due to a chemical signal.
Why doe juvenile solitary locusts not swarm?
Their eggs hatch in a lower density which stops them from bumping into each other.
What are rotifers?
Small protozoa like creatures that live in ponds.
How will rotifers develop without the presence of predators?
If there are no predators present then they will lack spines on their body.
How will rotifers develop in the presence of predators?
They will develop large spines that come out of their body.
What is it that predators produce to induce a change in phenotype in rotifers?
Kairomones.
How did researchers prove that kairomones were responsible for inducing a change amongst their prey?
Researchers placed rotifers in water which had previously held predatory crabs.
Even though there were no crabs in the water, the phenotypic changes were still induced.
What is an opercula?
The hole in the mouth of a barnacle.
How will barnacles develop in an area without predators?
They will have a smooth opercula.
How will barnacles develop in an area with predators?
They will develop teeth on the inside of the opercula to deter predators.
How will carp develop in an area with predators?
They will develop a much larger body with more depth.
If daphnia develop in water that contains fly larvae, how will they develop?
They will develop pointy helmets.
Is the pointy helmet that develops in daphnia heritable?
Yes.
Even in the absence of predators, meaning that kairomones can alter gene expression in the daphnia as well as their phenotype.
Scientists used what, to see how the presence of a predator changed gene expression?
Daphnia.
How did scientists use daphnia to prove how the presence of a predator changed gene expression?
They exposed the daphnia to the kairomones of a predator and then compared the genes of 2 groups of organisms.
What was the method that scientists used to compare the 2 genomes of the daphnia to prove how the presence of a predator changed gene expression?
Differential display.
What did the scientists find after they performed differential display on the daphnia?
A new gene called DD1 which was the receptor for the kairomone.
What does the gene DD1 induce in daphnia?
The activation of the DD1 receptor turns on different gene expression. This new expression causes the production of the spiked helmet.
What genes have their expression altered by the DD1 gene causing the production of a spiked helmet?
The HOX genes.
Where do Costa Rican red tree eyed frogs lay their eggs?
In the folds of leaves that overhang a waterway.
What happens when the eggs of the Costa Rican red tree eyed frogs hatch?
The tadpoles will fall off the leaf and into the water.
What is a major predator of the juvenile Costa Rican red tree eyed frogs?
Snakes.
How can the tadpoles sense the arrival of approaching snakes?
They are able sense the vibrations caused in the branches by the approaching snakes.
How do the unhatched tadpoles respond to an approaching snake?
They respond by hatching prematurely and fall into the water.
How prematurely can the tadpoles hatch?
Up to 30% prematurely.
Where do spadefoot toads live?
In deep holes in desert environments.
What do desert toads wait for?
They cover themselves in a mucus layer and wait for rain.
What do desert toads do when it starts to rain?
They will come out of hibernation and lay their eggs in puddles.
Are tadpoles normally vegetarian?
Yes.
How can the tadpoles of the spadefoot toad become carnivorous?
If the puddle where they hatch dries out the density of tadpoles will get higher.
This will stress the tadpoles which induces metamorphosis.
It will also alter the gut of the tadpoles so they become carnivorous.
What hormones will be released in the tadpoles of the spadefoot toad to induce metamorphosis?
The stress of the tadpoles releases corticotropin which elevates the thyroid hormone and induces metamorphosis.
When tadpoles become carnivorous, will they grow faster or slower?
Faster.
What enzyme will convert testosterone to oestrogen in some organisms?
Aromatase.
What is it that activates aromatase?
Certain temperatures.
What is the temperature that aromatase is very active in a turtle embryo?
If the temperature of the turtle embryos rises above 30 degrees.
What happens when aromatase is activated in a turtle embryo?
It causes the embryo to hatch as a female.
If the temperature of a turtle embryo stays around 25 degrees, what will happen?
The offspring will be male.
What is the temperature that when aromatase will be activated in a turtle embryo?
28 degrees.
In snapping turtles and alligators, how is aromatase activated?
It is inhibited by a certain temperature range and is activated outside that range.
If aromatase is inactive in snapping turtles and alligators, what will be the sex of the offspring?
Males.
If aromatase is active in snapping turtles and alligators, what will be the sex of the offspring?
Females.
What herbicide can induce aromatase activity?
Atrazine.
If embryos are exposed to atrazine, what will happen to the offspring?
They will all be female.
Temperature can affect what on butterflies?
Their wing patterns.
Where do the butterflies live in the dry season?
They will live in leaf litter where temperatures are lower.
Where do the butterflies live in the wet season?
They will live higher up in the forest.
Butterflies that live in the cooler regions of the forest look like what?
Dried up leaves.
Butterflies that live in the warmer regions of the forest will develop what?
They will develop large eye spots on the wings to deter predators.
What is responsible for inducing the phenotypic changes in the butterfly wings?
An enzyme called 20-hydroxyecdysone (20-E).
What will 20-E do in butterflies?
20-E will alter the expression of DISTAL-LESS in the imaginal discs
What are the imaginal discs in butterflies?
Blocks of tissue in the pupa of the larva stage.
Low activity of 20-E is induced by what?
Low temperatures.
High levels of 20-E will be caused by what?
High temperatures.
In temperate regions, what lead to the expression of20-E?
The length of the days.
In temperate regions when are low levels of 20-E occur and when will high levels of 20-E occur?
The activity of the enzyme is low in spring.
The activity of the enzyme is high in summer, when the days are longer.
Does 20-E lead to darker or lighter wings on butterflies?
Darker.
What leads to the expression of chromatin?
When DNA combines with proteins.
Chromatin is usually associated with what proteins?
Histone proteins.
When will DNA unwrap from the histone proteins?
When it is performing transcription.
What is chromatin called when it is not wrapped around histone proteins?
When it is performing transcription.
Are genes available in euchromatin or in chromatin?
In euchromatin.
When DNA is wrapped around the histones, what is this form of chromatin?
Heterochromatin.
In what form of chromatin are the genes unavailable?
Heterochromatin.
What happens to cytosine when heterochromatin is formed?
When the DNA base cytosine is methylated.
What enzyme causes the methylation of cytosine when heterochromatin is formed?
By the DNA methyl transferase enzyme.
Can the environment alter the structure of chromatin by changing euchromatin to heterochromatin and vice versa?
Yes.
How does temperature change euchromatin to heterochromatin?
By altering the methylation of cytosine.
What can cause hypomethylation of chromatin?
Certain toxins, such as arsenic, Bisphenol A and nickel.
Where is bisphenol A found?
In plastics.
Can maternal care, diet and hypoxia induce the methylation of cytosine?
Yes.
What happens if 2 sets of agouti mice are placed into foster mothers that are fed different diets?
Both sets of offspring will have different phenotypes due to the turning on of the agouti gene.
What is it that turns on the agouti gene?
If the pregnant mother is fed a diet without folate and homocysteine it will tun on the agouti gene.
If the agouti gene is turned on, what will the baby mice look like?
They will have a yellow coat.
What is it that turns off the agouti gene?
If the mother is fed a diet that includes folate and homocysteine, it will methylate the agouti gene.
If the agouti gene is methylated, what will be the phenotype of the offspring?
Brown.
What will good mothers do that alters gene expression in their offspring?
Groom their babies.
The grooming of baby mice will alter the expression of what promoter region of what gene?
The reduced methylation of the promoter of the glucocorticoid receptor gene.
Why is the glucocorticoid receptor gene important?
It is a very important gene for dealing with stress.
What happens to the promoter of the glucocorticoid receptor in the bad mothers of baby mice?
Low maternal care will cause around 100% methylation of the cytosine that turns off the glucocorticoid receptor.
Does methylation turn the glucocorticoid receptor on or off?
Off.
Reduced methylation of the promoter of the glucocorticoid receptor in mice results in what?
Higher levels of glucocorticoid receptor and an ability to handle stress better.
When the mother licks and grooms her babies, what will happen to the the cytosine of the glucocorticoid receptor?
It is tuned on and the mice are more relaxed over there lifetime.
As identical twins get older, what will happen?
They will look less and less identical due to the fact that their genetic makeup is mutating over their lifetime.
The methylation of which gene will change in women over time?
Oestrogen.
Does the methylation of genes change over time?
Yes.
When does the epigenetic marking such as DNA methylation occur?
When the sperm or egg is being made.
How will pregnant smoking women affect their baby foetus?
Because gametogenesis will be occurring in the female foetus and this will affect the methylation of her eggs.
How can pregnant women affect their grandchildren?
By smoking.
If men smoke during puberty, how will it affect their sperm?
It will alter the methylation of their sperm and therefore it can affect his children.
When scientists studied a Swedish village, how did they find that diet affected future generations?
That grandchildren of paternal grandfathers who had access to excess food during puberty had a 4 fold higher risk of dying of diabetes.
Also that the grandchildren of paternal grandparents who suffered from famine during puberty were protected from diabetes and cardiovascular disease.
