herps textbook questions
Chapter 4
What are advantages and disadvantages of external and internal fertilization in amphibians and reptiles?
External advantage/disadvantage: The ability to produce a large number of offspring with increased genetic diversity. BUT the chance of successful fertilization is reduced due to environmental factors like predators, water currents, and the possibility of gametes not coming into contact.
Internal advantage/disadvantage: Provides protection for the fertilized egg from predators and harsh environmental conditions. BUT often results in a smaller number of offspring produced at a time.
Why are sea turtles poor examples of r- versus K-selected species?
They are r selected but extremely fall off fast in terms of life span and then once they reach the ocean their life span increases insanely fast like a k selected species
What is the key difference in female reproductive systems between amphibians and reptiles?
The main difference is that many amphibians reproduce externally through their cloaca and pick up the sperm packet with the lips of the cloaca. At the same time, many reptiles have internal fertilization, as males may have one or two penises to pass sperm from their cloaca to the females.
Under what set of conditions would temperature-dependent sex determination (TSD) be advantageous when compared with gonadal sex determination (GSD)? Provide the underlying logical basis for your Answer.
Temperature-dependent sex determination (TSD) could be advantageous when compared with gonadal sex determination (GSD) if an increase in female offspring is needed for population survival or growth. Sex ratios were highly biased towards female offspring in documented instances of TSD in the Alligator mississippiensis (American Alligator) and Caretta Caretta (Loggerhead Sea Turtle) based on nest locations. Changes in temperature, nesting habits, and climate change can alter the nest temperature and then the sex of the offspring.
Explain how the transfer of genomes occurs in unisexual ambystomatid salamanders and why unisexual populations are able to persist.
Unisexual ambystomatid salamanders reproduce through hybridogenesis, which is when they incorporate sperm from males of parental species without using their sperm. This allows the hybrids to maintain populations and benefit from genetic variation, however they do experience limited overall genetic diversity.
What is the significance of a close relationship between egg size and size of the pelvic opening in the chicken turtle (Deirochelys reticularia)?
Most species have an optimal egg size that is based on the theory known as optimal offspring size theory. Turtles typically have a constraint on the egg size based on the width rather than the diameter of the pelvic aperture. The egg CAN'T exceed this, because turtles' pelvic girdle is less flexible than other reptile species. What makes chicken turtles (Deirochelys reticularia) unique is that the egg size really is dependent upon how large the turtle is. Smaller chicken turtles produce smaller eggs and larger chicken turtles produce larger eggs.
Describe the differences between the following unisexual methods of reproduction and give an amphibian or reptile example (species) of each.
Kleptogenesis— unisexual reproduction where females have a common cytoplasm but “steal” genomes from males of sexual species, which are not passed on to the next generation.
Hybridogenesis— the production of all-hybrid populations from two parental species.
Parthenogenesis—where each female produces identical daughters with no interaction with males of other species.
Chapter 5
How are the pathways involved in the evolution of viviparity different in amphibians and reptiles?
List and describe the different kinds of matrotrophy that are found in amphibians and reptiles.
Matrotrophy is when the mother provides the embryo with extra nutrients outside of the yolk. It is typically associated with viviparity (live birth).
The main kinds of matrotrophy in reptiles and amphibians are:
Maternal Dermatophagy: The embryo eats its mom's uterine lining during gestation and/or birth. The mother adds extra nutrients to her lining particularly fat and antibodies the embryo needs to survive. A good example is with viviparous caecilians.
Oviductal Histotrophy: The mother provides nutrients in the form of secretions produced by the oviduct that are absorbed by the embryo.
Placental Matrotrophy: The embryo develops a structure similar to a placenta seen in placental mammals. The structure provides nutrients, oxygen, and sometimes removes waste depending on the species. Some live-bearing skinks in the Mabuya genus have a placental-like structure found in placental matrotrophy.
Supplementary Matrorophy: The embryo relies mostly on the yolk but receives extra nutrients from the mom.
Oophagy: The mother lays unfertilized eggs for her young to eat. This is mostly seen in anurans that lay extra eggs for tadpoles to eat.
What are some reasons why amphibians exhibit such a diversity of reproductive modes whereas reptiles do not?
For Amphibians the breeding site, clutch structure, site of egg depositing, larval development site, and parental care, characterize amphibian reproductive modes. The complex variety is needed because of the diversity of reproductive blocks and their history.
Reptiles don't need the same characteristics as amphibians do for reproduction, and their reproductive systems are less complicated. They are separated according to whether they are oviviparous or viviparous and if their nutrition comes primarily from the yolk or partly from the mother and yolk.
Explain how one can determine the number of times that viviparity has evolved in squamate reptiles.
By mapping where viviparity shows up in the family tree, they can count how many separate times it evolved. If different branches of the tree show viviparity, it means it evolved independently in each branch. This method shows that viviparity evolved many times in squamate reptiles, often because it helps in cold environments where keeping eggs inside the body is better for survival.
Compare and contrast at least three different types of parental care found in amphibians and reptiles, and provide a real example of each.
Chapter 8
1. Using a reptile or amphibian species of your choice, discuss why you might expect the home range of a male to be larger than the home range of a female during the breeding season.
In males they must maintain all the females in their range and keep out any potential males that may pose competition but the females are more likely to be sought out then have to go searching for a mate.
2. When different methods were used to examine movement in the Malaysian snake Enhydris plumbae, the results were different. What were these different methods and how do you explain the differing results?
3. Describe movements in the life cycle of the green sea turtle and discuss orientation cues used by juveniles, immatures, and adults.
4. What is the difference between landmark orientation and x–y orientation and what are real examples of each?
Landmark orientation - I think about it as an internal compass. Salamanders use poloroized light to create their internal compass for orientation.
x-y orientation - using outside elements such as the sun or linear landmarks to create sense of direction. I couldn't really find an example on the internet or the book.
5. What are PIT tags and tantalum-182 tags, how do they work, and what can they be used for?
PIT tags and tantalum - 182 tags are tracking devices used on animals to track individuals and how they move around their environment. While the PIT tags are often used on sea turtles, they are small transponders that are activated by a low frequency radio signal from a scanning device.
Chapter 9
1. Describe parental care in the following: dendrobatid frogs (Dendrobatidae), the American alligator (Alligator mississippiensis), the cane toad (Rhinella marina), the broad-headed skink (Plestiodon laticeps), the gastric brooding frog (Rheobatrachus silus), and the western
coachwhip (Masticophis flagellum).
The American alligator (Alligator mississippiensis) and Broad-headed skink(Plestiodon laticeps)- protect eggs until hatching but provide no further care after hatching occurs
Cane toad (Rhinella marina) and Western coachwhip (Masticophis flagellum)- exhibit no parental care
Gastric brooding frog (Rheobatrachus silus)- the female swallows the eggs after they are fertilized and keeps them in her stomach during development. Once they have developed, she expels them and offers no further parental care.
Dendrobatid frogs (Dendrobatidae)- the males will transport the tadpoles on their back one at a time to a small tree hole. Here, the mother will deposit unfertilized eggs for the tadpoles as a food source
2. How does mating success differ between males and females in polygynous versus polyandrous mating systems?
In polygynous systems (where one male mates with multiple females), males often need to disperse farther than females to find available mates and secure territories. This increased competition means that males must travel to find unoccupied territories, whereas females tend to stay closer to resources or areas that provide protection from predators.
In polyandrous systems (where females mate with multiple males), the dynamics are different. Females can produce clutches with offspring sired by several males, which has been found to be more common than previously thought. This system allows multiple males to contribute to a single clutch, increasing genetic diversity. Studies have shown that males who are more distantly related to a female are more likely to sire her offspring than closely related males, adding another layer of selection.
3. If you found a new lizard species in which males were larger than females and had heads that were much larger than those of females, what are at least three possible explanations for such differences and how might those explanations cause the observed differences?
4. Prairie rattlesnakes are an example of the interaction between ecological factors and sexual selection. Define “operational sex ratio.” Then, based on your definition, explain how the ecology of these snakes influences on the operational sex ratio.
The operational sex ratio is the ratio of males to fertilized females at any given time.
Because the operational sex ratio is dependent on how many males there are to fertilized females, the ecology of these snakes influences the operational sex ratio, as female prairie rattlesnakes require the availability of food and heat to influence the frequency of reproduction. As they only mate with one single male at a time and are only sexually reproductive for a short time, some females may skip years of breeding. Because of these factors it results in a variable operational sex ratio; more males than females are available to breed at any one time.
5. Describe the differences between simple, compound, and complex displays in Anolis lizards. What kinds of information are transferred with these displays?
Simple: Involve a single, basic body movement or coloration change, usually used to communicate basic messages like territorial defense or mild aggression.
Compound: Combine multiple simple elements like body postures and coloration changes for more nuanced communication.
Complex: Involve elaborate sequences of movements and color changes, often used in courtship to convey strong mating interest and quality to potential partners.
6. Describe the numerous ways that frogs use acoustic signals in communication.
Frogs use many acoustic signals in communication, such as advertisement calls to attract mates ( territorial calls- defending territory , courtship calls- mating calls , encounter calls- male in response to another male calls ) Reciprocation calls are used by females in response to a male, release calls when a male initiates amplexus with another male and distress calls which are often when being predated upon.
Chapter 10
1. Describe in detail similarities and differences in how tongues work for prey capture in toads, plethodontid salamanders, and chameleons.
Chameleons have a hinged fork shaped tongue that shoots out like a hydraulic and is super fast, toads have short, broad tongues that flick out. Plethodontid salamanders have long, extendable tongues with sticky pads on the end.
2. Some lizards and many snakes can and do eat large prey. Describe how this is possible and compare how lizards that eat large prey differ from snakes that eat large prey.
3. Reptiles and amphibians are often categorized in two broad foraging modes based on foraging behavior. What are these foraging modes and what are the behavioral and energetic bases for these different modes? List as many ecological, morphological, and physiological correlates of each foraging mode that you can think of.
Sit-and-wait foragers:
Visually oriented or use thermal cues
Cryptic morphology/ coloration
Physiology that does well with making little movement
Active foragers:
Use a combination of visual and chemical cues
Well-developed chemical senses for detecting prey that is not moving or hidden
Less cryptic than sit-and-wait (often have to be more wary of predators)
Physiology should support a continually moving lifestyle
Greater home range
4. Although the argument has been made that herbivory in lizards is associated with large body size, recent data on small-bodied South American lizards suggests that large body size is not a necessary condition of herbivory. Moreover, phylogenetic analyses show that the evolution of herbivory has occurred much more frequently in small-bodied lizards. Explain the physiological arguments for associating herbivory with body size and the phylogenetic arguments that associate herbivory with small body size.
Larger herbivores have bigger and more complex digestive systems that help them break down large amounts of tough plant material efficiently. This allows them to consume a variety of plants to meet their higher energy needs. Smaller herbivores thrive in specific environments where they can access different types of plants. Their smaller size often helps them avoid predators, making it easier for them to find food without being seen. This combination of traits enables both large and small herbivores to adapt successfully to their plant-based diets.
5. Why might you expect ontogenetic dietary shifts to be more common in snakes than in lizards?
snakes growing more drastically than lizards, they have a much wider diet than lizards in terms of what prey they can eat, and snakes are entirely carnivorous.
Chapter 11
1. Recall the diagram of the sequence of events that can occur during a predation attempt (detection, identification, approach, pursuit, and capture). Choose any three events
and, using real examples (species), describe how the species make it through that event. Exactly how does the particular behavior result in escape?
I for real dont think this will be on the test because it refers to a diagram
2. Describe why tails of juvenile five-lined skinks are brilliant blue, but tails of adults are cryptically colored. Frame your answer in terms of costs and benefits.
the juveniles lift their tails to distract predators from attacking less protected/more vulnerable body parts. In adults, tails and their energy reserves are important for reproduction or reproductive-related activities. As a result, the cost/benefit ratio for tail autotomy changes. Tails of adult Plestiodon are cryptically colored similar to the body, and other predator-escape mechanisms become more important than tail autotomy
3. Why do some Acris crepitans tadpoles have black-tipped tails but others do not?
have black-tipped tails is because they live in an environment where one of their predators is the large dragonfly naiads. The black-tipped tail is a deceptive marking that allows the predator to target the tail versus the head or body of the tadpole. This increases the chances for tadpole to survive. Other tadpoles don't have that black tip because their predatolarge dragonfly naiadsrs are fish, which would be more of a target of swallowing the tadpole. These tadpoles have adaptative to have translucent tails.
4. What is meant by the “evolutionary arms race” and how does this work in garter snakes and newts?
evolutionary arms race refers to when predators and prey evolve in response to each other to stay equal. the newts that are eaten by garter snakes have very high toxin levels. Natricine snakes have a natural resistance to this specific toxin but the garter snakes specifically have up to 1000x the resistance seen in other snakes
5. Optimal escape theory makes some specific predictions with respect to risk and escape cost as a function of distance to predator. What are these, and what are some of the variables that might affect risk and cost in amphibians and reptiles?
Escape decisions of prey are based on assessed risk of mortality, costs of escape, and fitness of the prey. Age, sex, and reproductive condition affect its escape decisions indirectly by altering risk, cost, and fitness factors that directly influence escape decisions.
Chapter 18
Compare and contrast pleurodire and cryptodira turtles.
Pleurodire are unable to retract their neck back into their body cavity, so instead, they lay their head to the side. Which why they are more commonly called "side-neck turtles" cryptodira turtles can retract their necks into their body cavity
Turtles have been placed as a sister clade to all other “reptiles” by some authors and as a sister clade to crocodylians and birds by other authors. What evidence supports each of these placements of turtles?
Turtles have morphological similarities to both parties. More people have related them to birds and crocodylians. They both have similar scutes and conserved body forms. But people also found out that they lack the temporal fenestrae, which suggests that they are closer on the evolutionary tree.
How does the global distribution of the turtle family Chelydridae compare with that of the Emydidae, and can you think of possible explanations for these very different global distributions?
Chelydridae (snapping turtles) are found in the southern two-thirds of North America, including the southern states, Mesoamerica, and southern central America, including Ecuador. Snapping turtles are mainly aquatic only occasionally coming out to bask and lay their eggs.
Emydidae (sliders, box turtles, cooters) are found in Europe and North America. They are semi-aquatic, aquatic, and terrestrial depending on the species. American box turtles are completely terrestrial and sliders are semi-aquatic.
Their distribution is explained by how much time they spend in the water. Chelydridaes are very dependent on water rarely coming to land. Emydidaes are not as dependent on water so they can live in more areas.
Among turtles, which family is represented by the most living species, and does this family also have the largest global distribution?
Geomydidae is the family with the most extant(living) species around today but each of their species have small populations that are not cared for much by humans and are killed quite often so they do not have the largest global distribution. Dermochelyidae which are leatherback sea turtles, have the largest global distribution.
If you landed in Australia, what turtle families would you expect to find and how would you explain what you found?
Chelidae- lots of open waters and diverse marine life to sustain the populations
Dermochelyidae - as above
Chapter 19
1. Why has the phylogenetic position of Gavialis been so controversial among crocodylian systematists, and is the issue finally resolved?
researchers historically couldn’t agree on whether Gavialis should be more closely related to the other true crocodiles or placed in its own, separate lineage. Two types of evidence contributed to the confusion:
Anatomical Evidence: Early studies based on physical features grouped Gavialis separately because of its unique, highly elongated snout and narrow jaws, adaptations suited to its specialized fish-eating habits. These characteristics were distinct from both crocodiles and alligators, suggesting it might represent a separate lineage.
Molecular and Genetic Evidence: In recent years, genetic data complicated the picture even further by revealing that Gavialis shares some surprising similarities with crocodiles, leading some to propose that Gavialis could be more closely related to crocodiles than previously thought.
2. Can you provide a reasonable explanation why crocodylians have been such a successful group of reptiles and have remained relatively unchanged throughout their long evolutionary history?
being an apex predator in many of their habitats, crocodylians face limited competition from other large predators, which helps maintain their dominance in their ecological niches. Their body plans are designed to be both terrestrial and aquatic to exploit the resources in both environment.
3. The shape of jaws in crocodylians varies considerably among both living and extinct species. What are the functions of these different-shaped jaws?
Alligatoridae have broad, moderately long jaws that are used to catch and eat a wide variety of animals from fish to mammals to mollusks, and even other alligator species. Crocodylidae have a longer snout than Alligatoridae, with a more triangular rostrum to aid in larger prey capture and allow the fourth mandibular tooth to lie externally on each side of the mouth. Gavialidae have narrow, elongated, tooth-filled jaws that are very effective at capturing fish, their primary food.
4. Compare the crocodylian faunas of South America with those of Africa.
the two key differences are size and habitat. Crocodiles in Africa inhabit rivers, freshwater marshes, and mangrove swamps. South American crocodiles typically live in lagoons and wetlands found in forested areas. I also found that crocodiles in Africa tend to be larger as they tend to consume larger prey. Hope that helps some!
Chapter 20
Why are female tuataras able to produce but a single clutch of eggs every 4 years?
Females reach sexual maturity in about 13 years. Courtship and mating occur in January, but egg deposition is delayed until October–December of the following year. Development is slow and stops during the winter, and hatching occurs 11 to 16 months after egg deposition.
Considering the effect that introduced rats have had on populations of tuataras, design an effective conservation program that might work (assume that rats cannot be exterminated)?
Provide a safe area for the tuataras to breed and raise their young until theyre big enough to protect themselves against rats
Why are tuataras not considered “lizards?”
squamates apparently diverged early in the Late Triassic, and the rhynchocephalians seemingly have always been a group with moderate or low diversity
What Evidence Suggests That Sphenodon Tans May Not Have
been outcompeted by lizards during the Cretaceous?Priosphenodon avelasi was more abundant than any other tetrapod group in the Cretaceous beds of Patagonia, indicating that rhynchocephalians were the dominant tetrapods of the Cretaceous fauna of South America.
Chapter 21
Why is a snake a lizard?
a snake is considered a lizard because not only are they found in the same order, Squamata, but snakes comprise a monophyletic group that arises from a group of lizards. Snakes evolved from a species of small lizard
Loss of limbs has arisen independently in which clades of squamate reptiles, and what are some of the ecological and behavioral correlates of limb loss?
Serpentene, Anguimorpha, Dibamidae, Pygopodidae, Amphisbaenia and some Scincidae
The loss of limbs allows for a more fossorial lifestyle. Limbs might hinder movements within a substrate. Loss of limbs can help in loose leaf litter, sand, or substrate that undulation movement is more cost effective. Also, the ability to hide into areas that don't require limbs getting in the way or probe a new place to find food.
Considering that Tuataras (two species) are the only living representatives of a once very diverse clade (Sphenodontia), discuss the pros and cons of using Sphenodon to represent what the ancestor of squamates must have been like?
The Sphenodontida has acrodont dentition and a premaxillary enameled beak. Sphenodontidans were moderately diverse and abundant in Late Triassic and Jurassic, and largely disappeared from the fossil record thereafter. The terrestrial sphenodontidans had the body form still seen in the tuataras. Squamates are more abundant in numbers than tuataras, and tuataras are only found in New Zealand now.
Alternative hypotheses exist for the relationships of major clades of lizard squamates. A sampling of these can be seen by examining other textbooks, web pages, and field guides. Discuss why these differ, and which kind of evidence should be given the most weight, and why.
Alternate hypotheses exist for the relationships of major clades of lizard squamates because of the way classification was completed. Classification may have been completed with morphological traits, fossil records, and/or physical traits including scale patterns and skull structures. I think genetic data should be given the most weight because as we know two animals can look very similar but be entirely genetically different.
Chapter 22
Which family of snakes would you expect to be the dominant family in Australia and why do you think that that family has been able to dominate the snake fauna?
I would expect the family Elapidae to be the dominant family in Australia because they are venomous and eat a diet of almost exclusively vertebrates and lizards. They are also semifossorial and surface foragers.
What characteristics suggest that “snakes” are a monophyletic group of limbless lizards?
The characteristics that suggest snakes are a monophyletic group of limbless lizards is that they have no squamosal, no epipterygoid, no sclerotic ossicles in the eyes, and they lack a tympanum and the eustachian tube.
Describe some of the major differences (morphologically and ecologically) between viperids and elapids.
Morphological Difference: Viperids can move their fangs individually while elapids have fangs that don't move.
Ecological Difference: Viperids are worldwide except for Papuaustralia and oceanic islands. Elapids are in southern North America, South America, Africa, southern Asia, and Australia
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How do scolecophidian and alethinophidian snakes differ, both morphologically and ecologically, and what accounts for these differences?
Scolecophidian snakes are also known as blind or thread snakes. They are fossorial species snakes so similar to other fossorial animals they have reduced eyes that are mostly capable of detecting light and dark.
Alehtinophidian snakes are every other snake species. They have been grouped into families based on their teeth and are far more ecologically diverse than blind snakes.