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zBIO 3147 - Animal Development > Ecological and Evolutionary Development (lec 20/21) > Flashcards

Ecological and Evolutionary Development (lec 20/21) Flashcards

1
Q

What is the classic view of genetics?

A

Genotype is the only contributor of Phenotype!

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2
Q

While a wild-type fly has regular antennas, an antennapedia mutant has legs instead of antennas. How can this be caused?

A

Caused by artificial laboratory-induced GENE MUTATION in flies (non-adaptive phenotype).

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3
Q

The Beak Variation amongst Darwin’s Finches is caused by:

A

Natural selection on quantitative VARIATION IN GENES (adaptive phenotype).

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4
Q

(T/F) Envrionment can interact with genes and have profound consequences on phenotypes. It is most impactful during development!

A

True!

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5
Q

How did Ronald Fisher (father of modern evolutionary theory and population genetics) view environmentally generated phenotypes?

A

He viewed them as noise!

“It is not surprising that such elaborate machinery (genotype –> phenotype) should sometimes go wrong”

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6
Q

1) What is the modern view of Ecological Developmental Genetics?

2) What is developmental plasticity?

A

1) Genotype + Environmental factors —(development) —> Phenotypes

2) The ability for a single genotype to give rise to alternative (different) phenotypes due to environmental variation acting on developmental processes.

*environmental factors can be biotic & abiotic

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7
Q

(T/F) Biotic factors include things such as climate, temperature, pH, rain and while abiotic factors include things such as food availability, symbiosis, bacteria, competition, predation, and social interaction.

A

False!

ABIOTIC factors include things such as climate, temperature, pH, rain and while BIOTIC factors include things such as food availability, symbiosis, bacteria, competition, predation, and social interaction.

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8
Q

Briefly describe the “triple helix”.

A

Through different combinations of genes (type A and B) and environment (type I and type II), a huge number of phenotypes are generated!

Instead of just gene type A —> phenotype type A .

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9
Q

Describe the Epigenetic Landscape concept determined by C.H. Waddington.

A

There is a hill with lots of valleys. When the ball is rolling down the hill, it can go through any of the valleys, leading to different phenotypic outcomes.

The different trajectories resemble the different development trajectories. Which trajectory taken can be influenced by the environment!

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10
Q

The food the newly hatched larva is being fed determines whether it will be a queen bee or a worker bee.

______ ____ is fed to queen bees.

A

Royal jelly

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11
Q

Royal jelly _____ body growth, ovary development, queen organs, while it ______ neurogenesis and worker organs.

Worker food _____ body growth, ovary development, queen organs, while it ______ neurogenesis and worker organs.

A

Increases; Decreases

Decreases; Increases

*this is due to EPIGENOMIC and HORMONAL responses that affect gene regulation and tissue & organ differentiation, ultimately leading to caste determination.

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12
Q

What are the key components of royal jelly and of worker jelly that lead to caste plasticity in bees?

A

Royal jelly: Juvenile Hormone and Royalactin

Worker jelly: miR162a and Queen Mandibular Pheromone

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13
Q

Royalactin is a key component of the queen’s diet while Casein is part of the worker’s diet.

How do these influence ovary size and weight at adult emergence?

A

Royalactin increases ovary size significantly while Casein has minimal effects on ovary size.

Royalactin also increases weight at adult emergence significantly while Casein has mild effects on weight at adult emergence.

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14
Q

There is a high plant miRNA level in _____ and a low plant miRNA level in ________. Thus, leading to worker bees and queen bees.

A

Pollen (worker food); Royal jelly (queen food)

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15
Q

(T/F) miR162a and Royalactin activate and suppress different pathways, leading to the two different castes.

A

True!

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16
Q

What is the phenotypic difference between a wet-season female butterfly and a dry-season female butterfly?

A

Wet season female: huge eyespots in the wings - important for defence!

Dry season female: lacks the huge eyespots but has incredible leaf/ground camouflage to help it wait until the wet season comes back

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17
Q

If the larva is growing at temperatures >24˚C, there is a _______ amount of ________ which causes expression of _______ in the imaginal disc, leading to wet season form.

If the larva is growing at temperatures <20˚C, there is a ______ amount of _______, leading to no expression of _______ in the imaginal disc, leading to dry season form.

A

Increased; 20-hydroxyecdysone; Distal-less

Decreased; 20-hydroxyecdysone; Distal-less

*Distal-less induces eyespots formation!
*Abiotic: temperature

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18
Q

How does a mole salamander larva become a metamorph and a paedomorph?

A

Metamorph: high thyroid hormone, drought-induced metamorphosis

Paedomorph: low thyroid hormone, low predator ponds

*Biotic: predator & Abiotic: drought

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19
Q

(T/F) Predator and prey-induced plasticity is an abiotic factor!

A

False!

It is a biotic factor.

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20
Q

Crustaceans’ predators produce ________/________ which the prey (crustaceans) can detect.

High levels of predation lead to:

Low levels of predation lead to:

A

Allelochemical/Kairomones

Lots of kairomones; crustaceans develop a horn to defend against predators.

Low levels of kairomones; no horn formed.

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21
Q

What is the difference between pheromones and kairomones?

A

Pheromones: produced within species

Kairomones: Produced by one species that another species can respond to

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22
Q

Pre-induced plasticity is seen in New Mexico spadefoot toads. Describe it.

A

Depending on what the mother is consuming; either a CARNIVORE diet (other tadpoles) or an OMNIVORE diet (brine shrimp, algae), the intestines and jaw developed of the baby is optimal to the diet it was fed.

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23
Q

Environmental factors determine which caste a developing ant will become.

What factors determine these?
1) Queen vs worker

2) Soldier vs worker

A

Queen vs worker: Abiotic (temp + photoperiod)

Soldier vs worker: Biotic (nutrition)

*IT’S THE SAME GENOME BUT DIFFERENT PHENOTYPES!

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24
Q

(T/F) Caste differentiation is similar to cell differentiation.

A

True!

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25
Q

If the ant embryo is expressed to high levels of _____ ______ (due to temperature and photoperiod), it becomes the queen.

There is a second switch point of ______ _____ in larva development and if the larva is exposed to high levels of nutrition, they become the ______ and if they are not, they become the _____ ______.

A

Juvenile Hormone

Juvenile Hormone; Soldiers; Minor Workers

*Darwin: phenotypes of a species can be so different due to non-genetic mechanisms (epigenetic/hormonal) that you think they’re different species!

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26
Q

What is SIP?

A

Soldier Inhibitory Pheromone

This is expressed by the soldier ants. If there are lots of soldiers, there is an accumulation of the SIP, which blocks the production of more soldiers.

27
Q

DNA methylation can mediate gene-by-environment.

What does it do? Where is it done?

A

DNA methylation turns off gene transcription.

If the Cytosine of a CG is methylated, gene transcription is turned off.

This is a reversal process just like how environment is also reversible.

28
Q

(T/F) DNA methylation can not be inherited.

A

False!

It can be inherited from one generation to the next!

29
Q

What is the role of DNA methylation in ants?

A

Quantitative DNA methylation of Epidermal Growth Factor Receptor (Egfr) regulates WORKER ANT SIZE VARIATION.

Worker size is sensitive to nutrition (protein) levels.

30
Q

DNA methylation regulates ____ _____ plasticity in mice.

How?

A

Coat-colour

Dietary folate is a methyl donor. Increased levels of dietary folate = increased DNA methylation.

DNA methylation of the viable-yellow of Agouti-TRANSPOSON in cis-regulatory elements turns on/off pigmentation genes, leading to different pigmentations.

31
Q

_______ _______ regulates plasticity of sex.

A

Histone Methylation

*in turtles and alligators

32
Q

(T/F) In onthophagus beetles, there is a horned male and a hornless male.

Decreased body size increases horn length through Juvenile hormone (JH) - mediated threshold.

A

False!

Though there are horned and hornless males in onthophagus beetles.

INCREASED body size increases horn length through Juvenile hormone (JH) - mediated threshold.

33
Q

What are the 4 major parameters of the evolution of Onthophagus sexual dimorphism?

A

1) Location (where is the horn)
2) Shape (how big is the horn)
3) Allometry (proportional sizing)
4) Sexual dimorphism (females do not have horns)

34
Q

Which one of the statements regarding sex determination pathway in beetle horn plasticity is true?

1) Males and females have the same doublesex isoform with the same roles.

2) Large males downregulate dsx compared to small males and females.

3) Male doublesex RNAi reduces large horns of large males and induces ectopic horns in hornless females.

A

3!

1) Males and females have UNIQUE doublesex isoforms with the OPPOSING roles.

2) Large males UPREGULATE dsx compared to small males and females.

35
Q

(T/F) There is diet-induced oral jaw plasticity in cichlid fish. They can be either Biters or suckers.

A

True!

Cichlid fish also have pharyngeal jaws. Both (oral and pharyngeal) jaws have teeth.

36
Q

While a hard diet leads to a ________ lower pharyngeal jaw, a soft diet leads to a ______ lower pharyngeal jaw.

A

Molariform; Papilliform

37
Q

How did cichlids evolve diverse jaw morphologies?

A

They developed different features to adapt to non-overlapping territories in the different lakes (Tanganyika vs Malawi).

Different food substrates in the lakes; different jaws!

This could lead to speciation over time.

38
Q

What is Evolutionary Development (EVO-DEVO)?

A

It is understanding how variation develops in order to better understand how variation can evolve.

39
Q

Genome organization, Expression pattern and Function of _____ genes are extremely evolutionary conserved!

A

Hox

40
Q

A zygote becomes a ______ and then a _______, where it forms the germ layers (ectoderm, mesoderm, endoderm, and germ cells).

A

Blastula; Gastrula

41
Q

How can there be evolution of novel cell and tissue types through embryonic germ layers?

A

Different mechanisms give rise to the different cell types & lineages, and the mechanisms can be modified and lead to the evolution of various different cell and tissue types.

*the way germ layers move and behave in space + time, and the way they’re interacting with each other (signalling factors) during gastrulation can all be modified across evolution.

42
Q

What is the question Eco-Evo-Devo asks?

A

How does environmental variation influence developmental processes and how can this lead to phenotypic diversification and evolution?

43
Q

_______ variation in the context of Evolution, and ______ variation in the context of Medicine are two sides of the same coin.

________ is at the crossroad between Eco-Evo/Med-Devo.

A

Adaptive; maladaptive

Development

44
Q

(T/F) There are many pathways that are very conserved across organisms such as the insulin and proproliferation pathways.

A

True!

*insulin is conserved across flies, c.elegans, and mammals

*proproliferation is conserved across flies and mammals

45
Q

The _____ gene for eye development is an example of a gene ancestral to both ______ and _______.

What happens when this gene from a mouse is expressed in the leg disc of a fly?

A

Pax6; protostomes; deuterostomes

Ommatidia of the compound insect eye emerge in the leg of a fruit fly (a protostome) in which mouse (deuterostome) Pax6 cDNA was expressed in the leg disc.

*this is an evidence of the evolutionary conservation of regulatory genes from flies to mammals.

46
Q

Wild-type mouse: regular limbs

Limb enhancer deleted mouse: very tiny limbs

Human shh enhancer point mutations: abnormal limbs

How can this evidence be used in a biomedical and evolutionary context?

A

Biomedical context: study mouse enhancers to get a better understanding of what’s perturbed during development that can lead to these phenotypic variants in humans.

Evolutionary context: similar point mutations (molecular evolution) can lead to novel + adaptive forms of limb variation

*development at the crossroads of evo-devo-med

47
Q

Python ZPA cells have a _____ and _____ SHH due to mutations in the cis-regulatory elements, causing ______ _________.

Limbed tetrapod ZPA cells have a ______ and _____ SHH, causing ______.

A

weak; transient; limb reduction

normal; sustained; pentadactyl

48
Q

What are the four fundamental kinds of large-scale, evolutionary differences in morphology prevalent in modularly organized animals?

A

1) Meristic variation: changes in the number of repeated parts (segment #, vertebral #)

2) Serial homology: diversification of serially homologous parts (antennae, legs, genitalia - arms and legs are serial homologous parts)

3) Homology diversity: diversification of homologous parts (ex. differences in arms alone across organisms)

4) Origin of novelties: new characters, from pre-existing structures or de novo (feathers, teeth, antlers, butterfly eyespots, etc)

49
Q

Give an example of diversification of homologous parts.

A

The humerus is a homologous skeletal element across humans, seals, birds, and bats.

But certain paths for the animals were tinkered with, leading to different morphologies of the humerus for all!

50
Q

(T/F) Developing bat wings versus mouse forelimbs is a diversification of homologous parts.

A

True!

They start in the same manner but eventually develop into different morphologies.

51
Q

What is deep homology?

Give two examples.

A

Deep homology is when structures at the surface appear very different but the underlying gene regulatory network that forms these structures are very anciently conserved!

First example: Fly wing to human arms, seal limb, bird limb, bat wing

Second example: The human heart and the heart of a fly are analogous in function and look totally different but they are made in a very similar way (underlying gene network is very similar)

52
Q

Match the following terms to their definitions regarding gene expression and novelty:

1) Heterotrophy
2) Heterochrony
3) Heterometry
4) Heterotypy

A) shift in the timing of the expression of a gene
B) shift/change in the actual protein that is made, example: mutation of a hox gene that enables it to suppress the function of another developmental gene.
C) shift in the spatial domain of expression of a gene
D) shift in the amount/levels of expression of a gene

A

Heterotrophy: shift in the spatial domain of expression of a gene

Heterochrony: shift in the timing of the expression of a gene

Heterometry: shift in the amount/levels of expression of a gene

Heterotypy: shift/change in the actual protein that is made, example: mutation of a hox gene that enables it to suppress the function of another developmental gene.

53
Q

The differences in beak morphology in the five species of Darwin’s finches correlate with _________ and _______ changes in _____ expression in the beak.

It is expressed _______ and at _____ levels in the seed-crushing ground finches (BROAD and DEEP beaks), versus the LONG-POINTED BEAKS of ______ finches.

A

Heterochronic; heterometric; Bmp4

Earlier; higher; cactus

54
Q

What does a RCAS:Bmp4 infection in the mesenchyme of the frontonasal process cause?

A

It causes a significant increase in the WIDTH and DEPTH of the beak mirroring what is found in the seed-crushing finches who naturally express high levels of BMP4 in the mesenchyme!

55
Q

What is RCAS?

A

Viral vectors that are competent to replicate in infected cells, can insert a gene of interest in the virus genome leading to the expression/upregulation of the gene of interest.

56
Q

A gene with four different functions can undergo duplication and then divergence using these 3 mechanisms. Describe each

1) Subfunctionalization
2) Neofunctionalization
3) Degeneration/Gene loss

A

1) Subfunctionalization: one copy has two functions while the other has the other two functions

2) Neofunctionalization: one copy retains all four functions while the other has novel functions

3) Degeneration/Gene loss: one copy retains all four functions while the other loses all functions

*these can all lead to novelty

57
Q

What is the difference between the drosophila eye/head development versus the stalk-eyed fly development?

A

Engrailed and Wingless play a role in both.

But the engrailed and wingless shift in the spatial expression, allowing the stalk-eyed fly to grow those eyes to protrude from the face and grow outward.

58
Q

(T/F) Male stalk-eyed flies extend their eyes for courtship behaviour; example of the evolution of sexual dimorphism.

A

True!

59
Q

Limbs of cephalopods, arthropods and vertebrates are an example of ________ evolution.

A

Convergent

*similar TFs, morphogens have been demonstrated to pattern the dorsal/ventral, proximal/distal axis of the developing limb!

60
Q

What is hedgehog signalling essential for?

A

It is essential for SUCKER FORMATION of tentacles and arms.

61
Q

(T/F) BMP2/4 is important for dorsal/ventral pattern. If you expressed hedgehog in abnormal regions (where it is not normally expressed), there is a mirror duplication.

A

True!

62
Q

What is Gremlin?

A

A natural BMP antagonistic factor.

It inhibits interdigital cell death (apoptosis) that occurs during limb formation.

63
Q

Chickens naturally _______ gremlin in their foot webbing leading to apoptosis of webbing while ducks naturally ______ gremlin in their feet and that leads to the retention of foot webbing.

Furthermore, developing chicken feet experimentally given extra gremlin causes them to _____ their webbing.

A

Downregulate; Upregulate

Retain

zBIO 3147 - Animal Development (11 decks)

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