Herpetology Exam 2, Part 2

Front 1

As embryos, all vertebrates start out with indifferent gonads. What are these?

Back 1

undifferentiated gonadal tissue that remains as such until hormonal cues switches genes on/off.

Front 2

What are the 4 basic genotypic sex-determining systems found in amphibians?

Back 2

1) XY system - Y chromosome determines sex

2) ZW system - W chromosome determines sex (ZW= female)

3) XY multiple

4) ZW multiple

Front 3

Which sex is the heterogametic sex in mammals?

Which sex is the heterogametic sex in most amphibians?

Back 3

Mammals: males (XY)

Most amphibians: females (ZW)

Front 4

What are some examples of environmental cues that can modulate the reproductive cycle of amphibians?

Back 4

-water availability

-photoperiod length

-temperature

Front 5

What are the steps of the cascade that happens to prepare amphibians for gamete production/reproduction?

Back 5

1) environmental cues trigger hypothalamus to release GRH

2) GRH goes to the anterior pituitary

3) anterior pituitary releases gonadotropins (FSH and LH)

4) FSH and LH go to the gonads

5) Gonads produce testoterone/estrogen to make a) gametes and b) secondary sex characteristics

Front 6

As far as modes of fertilization goes, what is the ancestral condition: external fertilization or internal fertilization?

Back 6

External fertilization (eggs deposited, much like fish)

Front 7

What is mostly found in salamanders: external or internal fertilization? Where do you find the less-commonly used mode?

Back 7

Internal fertilization is most common.

External fertilization is used in Cryptobranchoidea

Front 8

How does internal fertilization work in salamanders?

How can females retain sperm?

Back 8

Males deposit a spermatophore and the female take it into the cloaca.

Females can retain sperm for months inside spermatheca within the oviduct.

Front 9

What is typical in Frogs: external or internal fertilization?

Back 9

External fertilization.

Front 10

How does external fertilization work in frogs?

Back 10

females oviposit eggs and males lay sperm on top of it.

Front 11

Why do males perform amplexus during oviposition/external fertilization?

Back 11

To ensure that his sperm is the sperm that reaches the eggs.

Front 12

What types of amplexus tend to be used by frogs that lay eggs in water?

What type of amplexus is used by frogs that lay eggs on land?

Which is the most "primitive" form of amplexus?

Back 12

In water: inguinal and axillary

(Inguinal=ancestral condition)

On land: cephalic (in Dendrobatids)

Front 13

Male frogs who perform axillary amplexus have _______ _________ on the fourth digit for grasping.

Back 13

nuptual pads

Front 14

The few viviparous species of frogs practice ______________ fertilization.

Back 14

internal

Front 15

For frog species who practice internal fertilization AND lay eggs, what do the males have?

Back 15

They have a permanently inverted/external cloaca.

Front 16

What type of fertilization (external/internal) do ALL Caecilians practice? What do male caecilians have to help with this?

Back 16

Internal fertilization. Males have a phallodeum that's stored inside the cloaca except during the breeding season.

Front 17

Most amphibians have haploid gametes that fuse to make a diploid offspring. However, some species practice ___________________

Back 17

hybridogenesis: parents from 2 different species make a hybrid offspring.

Front 18

Some amphibians practice kleptogenesis. What is this?

Back 18

All female populations mate with males of a different species to "steal" a sperm. The sperm breaking through the egg triggers development of eggs, but the sperm genome is not incorporated.

Front 19

In viviparous species, fertilized eggs go through __________ cleavage.

In oviparous species, eggs go through ____________.

Back 19

Viviparous: complete cleavage.

Oviparous: Lecithotropy: egg splits into a vegital pole (becomes yolk) and animal pole (becomes egg)

Front 20

In embryonic development, what is gastrulation?

Back 20

formation of the 3 germ layers.

Front 21

During nerulation, what does the ectoderm become?

What does endoderm (yolk) become?

Back 21

ectoderm --> nervous system

endoderm --> gut

Front 22

Are caecilians mostly viviparous or oviparous?

Back 22

oviparous.

Front 23

What do larvae of oviparous caecilians eat?

What do larvae of viviparous caecilians eat?

Back 23

oviparous = dermophagy

viviparous = oviduct epithelium secretions

Front 24

Are salamanders mostly oviparous or viviparous?

Back 24

oviparous

Front 25

What are the 3 different modes of egg laying in oviparous species of salamanders?

Which mode has the largest eggs? Which mode has the smallest eggs?

Back 25

Mode 1: lays eggs in ponds

Mode 2: lays eggs in stream (tend to have larger eggs)

Mode 3: nonaquatic eggs (largest eggs)

Front 26

Within Mode 3 (non-aquatic egg layers) of salamanders, what are the 3 subcategories of locations of nests in this mode?

Back 26

1) terrestrial nest

2) arboreal nest)

3) eggs retained in oviduct

Front 27

what are the 3 notable things that larval salamanders have?

Back 27

1) lateral line system

2) gills

3) tail fin

Front 28

What are the ways that frogs lay eggs?

What kind of oxygen environment is associated with each way?

Back 28

1) egg masses in water

-communal egg laying, high oxygen levels

2) egg masses in long strings on water surface

-warm water OR low oxygen levels

3) foam nests

Front 29

What are 2 examples of parental care in frogs?

Back 29

1) egg attendance

2) dart frogs carry tadpoles and put them in arboreal plant nests and then do rounds.

Front 30

What are 3 alternate locations where some frogs brood eggs outside of the reproductive tract?

Back 30

1) vocal sac

2) on the female's back

3) stomach

Front 31

how do gastric brooding frogs prevent digestion of their eggs?

Back 31

The eggs release hormones that stops digestion

Front 32

What are the 3 benefits of parental care in frogs?

Back 32

1) lower pathogens/predation

2) aeration

3) prevention of dessication

Front 33

What are the 3 downsides to parental care in frogs?

Back 33

1) lower reproductive output of parents

2) lower food intake of parents

3) lower survival of parents

Front 34

What factors can influence egg size and clutch size?

Back 34

1) direct development (larger) VS metamorphosis (smaller)

2) aquatic (smaller) versus non-aquatic (larger)

3) food availability

Front 35

What is the major benefit to species developing complex/larval development?

Back 35

Less competition between adults and larvae

Front 36

Frog larvae are Suspension Feeders. What does this mean?

Back 36

They draw water into the mouth, strain it and squirt it out through the spiracles.

Front 37

Describe the hormonal cascade that triggers growth and metamorphosis in tadpoles?

Back 37

1) Environmental triggers stimulate CRF

2) CRF triggers ACTH release

3) ACTH goes to adrenal glands

4) adrenal glands release corticosteroids

Front 38

What does the Wilbur Collins model of development and metamorphosis say?

Give an example of the model in action.

Back 38

Says that there's a lot of factors that go into when metamorphosis versus growth occurs in amphibians.

-Ex: You can alter the # of tiger salamanders that remain paedomorphic as adults by changing environmental conditions.

Front 39

What kinds of reptiles have temperature-dependent sex determination?

Back 39

1) ALL crocadylians

2) tuataras

(3) some lizards, some turtles)

Front 40

What are the 3 patterns of temperature-dependent sex-determination can you find in reptiles? Which kinds of reptiles ascribe to which pattern?

Back 40

1) Pattern A: cool = male, warm = female

-found in turtles

2) Pattern B: cool = female, warm = male

-found in tuataras

3) Pattern C: Females made at extreme temperatures, males are made in the middle of the bell curve.

-crocadylians, turtles

Note: squamates participate in all 3 patterns

Front 41

Describe the cascade of hormones that occurs when producing males in temperature-dependent sex differentiation.

Back 41

1) "male" temperatures trigger 5alpha-reductase production

2) --> 5a-reductase converts testosterone in yolk to dihydrotestosterone (DHT)

3) DHT binds to receptors on undifferentiated tissue to start developing testes.

Front 42

Describe the cascade of hormones that occurs when producing FEMALES in temperature-dependent sex differentiation.

Back 42

1) "female" temperature triggers production of aromatase.

2) Aromatase converts yolk testosterone into estradiol.

3) estradiol binds to estradiol receptors on undifferentiated tissue to start developing ovaries.

Front 43

What is the main advantage of a gene-dependent sex determination (GSD)?

Back 43

1:1 sex ratio

Front 44

What does the Charnov-Bull Model say?

Back 44

In species with temp-dependent sex determination, "The fitness of each sex is highest when they're produced at temperatures that normally produce that sex."

Front 45

What are the 3 common features of asexual squamates?

Back 45

1) Originate by hybridization of 2-3 species

2) all individuals are female

3) reproduction happens through parthenogenesis (AKA clonal inheritance)

Front 46

Hybrid squamates can either be __________ unisexual or ____________ unisexual

Back 46

diploid, triploid

Front 47

In asexual species, what 2 things differ during meiosis (production of gametes)?

Back 47

1) genome doubles BEFORE meiosis

2) gamete ends up being diploid (instead of haploid like normal), so it's essentially already a fertilized zygote.

Front 48

All reptiles practice oviparity (egg-laying) except which reptiles?

Back 48

20% of squamates (lizards and snakes)

Front 49

In reptiles, the outer layer of the eggshell is made of calcium carbonate deposited in discrete structures called ______ _______.

Back 49

shell units

Front 50

What is unique about the shell units of tuataras?

Back 50

They're embedded in the shell membrane

Front 51

Which species of snake has the largest egg for their body size of any reptile?

Back 51

pythons

Front 52

What are the 2 main difference between rigid reptile eggshells and flexible reptile eggshells?

Back 52

Rigid:

-contain all the water embryo needs to develop

-really good at preventing H2O loss

Flexible:

-have to take up water from environment

-less good at preventing water loss

Front 53

In viviparous reptiles, what is the corpus luteum and what does it secrete?

Back 53

Corpus luteum = follicular part of the ovum. It secretes progesterone

Front 54

What's the difference in gas exchange between oviparous eggs and viviparous eggs?

Back 54

Oviparous eggs: gas exchange happens through the chorioallantoic membrane.

Viviparous eggs: chorioallantoic membrane becomes the placenta and attaches to the uterine wall to allow gas exchange through mom's circulatory system

Front 55

Why are squamates the only viviparous reptiles?

Back 55

In other reptiles, development doesn't start until oviposition occurs.

However, in squamates, development starts right at fertilization, providing fertile ground for the development of viviparity.

Front 56

There's a continuum of oviparity versus viviparity. Eggs left in the oviduct longer are closer to viviparity. What is an example that illustrates this?

Back 56

Oviparous reptiles with long periods of egg retention in oviduct have a short egg incubation and thin egg shells.

Front 57

What does the Cold Climate Hypothesis say?

What evidence is there of this hypothesis?

Back 57

It's more adaptable to retain eggs longer in colder climates because they develop better.

-Evidence: most viviparous squamates live in cold climates.

Front 58

In all reptiles and amphibians, which atrium receives oxygenated blood? Which atrium receives deoxygenated blood?

Back 58

Left atrium receives oxygenated blood.

Right atrium received deoxygenated blood.

Front 59

How many chambers does the amphibian heart have?

Back 59

3: 2 atria and a single ventricle.

Front 60

What 2 parts of the amphibian heart keep the oxygenated and deoxygenated blood separate in the ventricle?

Back 60

1) The spiral valve

2) Ventricular trabeculae

Front 61

What is unique about the aorta of reptiles?

Back 61

All reptiles have 2 aortas.

Front 62

How many chambers does the heart of squamates/turtles have? What characterizes these chambers?

Back 62

3 chambers: left and right atrium and a single ventricle. However, the ventricle has a partial septum.

Front 63

In squamates and turtles, the ventricle is divided into 3 subchambers. What/where are they?

Back 63

1) Cavum pulmonale (on the right)

2) Cavum arteriosum (on the left)

3) Cavum venosum (behind the first 2)

Front 64

What is the path of deoxygenated blood through the squamate/turtle heart?

Back 64

Deoxy blood goes cavum venosum --> cavum pulmonale --> out thru pulmonary artery to lungs

Front 65

What happens to the oxygenated blood when the ventricle contracts in the squamate/turtle heart?

Back 65

Oxygenated blood flows through the intraventricular canal out through the 2 aortas.

Front 66

True or false: In aquatic squamates, turtles and crocadylians, they can bypass the pulmonary circuit while under water.

Back 66

TRUE

Front 67

How many chambers does the crocadylian heart have? What characterizes these chambers?

Back 67

4 chambers

Front 68

What is the name of the tube that connects the 2 aortas in crocadylians?

Back 68

The Foramen of Panizza.

Front 69

Describe the path of oxygenated blood through the heart of a crocadylian when its ventricles contract.

Back 69

Left ventricle is larger because it pushes against all of systemic circulation.

Left ventricle contracts --> oxygenated blood is forced through the foramen of Panizza into both aortas.