Unit 3 - Herpetology

Define fitness.

The relative reproductive success of an individual

Significant because having high reproductive success means your genes persist through the next generation

All amphibians have what type of sex determination?

All genetic = sex determined at fertilization

AKA: genotypic sex determination

Which sex (male or female) is the ancestral heterogamety of the amphibians?

Female

What type of fertilization is found in both Gymnophiona and Urodelans?

Internal

What type of fertilization is found in Anurans?

External

Describe the difference between a spermatophore and spermatheca.

Spermatophore = the sperm packet the MALE deposits

Spermatheca = pocket inside the cloaca of a FEMALE where the sperm is stored

Describe the egg size gradient among the Amphibians in relation to differing environments.

Bigger eggs are more likely more terrestrial amphibians

Intermediate sized eggs are found in aquatic environments where oxygen is DEPLETED

The smallest eggs are found in aquatic environment where oxygen is HIGH

Define Parthenogenesis.

The ability to reproduce within species without needing sperm from a male, where offspring are identical to the females

Significant because it allows a species to colonize with just one species established

Ex: Brahminy Blind Snake

Explain the difference in genetic diversity when it comes to parthenogenesis.

There is a HIGH genetic diversity within the individual, but a LOW genetic diversity in their populations

What is hybridogenesis?

A hybrid frog (ex AB) mates with a “normal” frog (ex BB), but the hybrid female recognizes the “B” in the environment (from the normal frog), so she gets rid of the “B” gene as a hybrid, making the “A” gene undergo gametogenesis to produce further hybrids

Ex: Pelophylax esculentus complex (P. lessinae + P. ridibunda)

What is gynogenesis?

It is similar to parthenogenesis, but the development of the egg doesn’t begin until sperm is present in the egg; HOWEVER, no genetic material from the sperm is incorporated into the offspring

Ex: Ambystoma jeffersonianum complex

What is kleptogenesis?

This is similar to gynogenesis and parthenogenesis, EXCEPT the female uses some of the DNA from the male, just not all of it; “klepto” = to steal

The offspring are normally triploid, tetraploid, or even pentaploid

Ex: lots of Ambystoma do this

Why are breeding displays important?

They signal about an individual’s fitness (which some can lie about)

It indicates the species to avoid hybridizing

Why have some Amphibians selected toward more terrestrial eggs?

To avoid predation

What is an example of an amphibian that lays their eggs in seasonal pools?

Lithobates sphenocephalus

Hyla versicolor

Psuedacris species

Ambystoma species

Give an example of a frog that lays its eggs in vegetation above the water.

The red eyed tree frog

Give an example of a frog that lays their eggs in foam nests on the water’s surface.

The weeping dwarf frog

Give an example of a frog that lays their eggs in foams nests mainly ABOVE the water.

Physalaemus pustulosus

Explain how some Dendrobatids (like the strawberry poison dart frog) lay terrestrial eggs and carry the tadpoles.

They often lay their eggs in Bromeliads, which has little water and/or sunlight; the male guards the tadpoles and when they are ready to eat, he goes to find the female (with the tadpoles on his back) where she lays both fertilized and unfertilized eggs for the tadpoles to eat

What genus of frogs carry their eggs until they are about to hatch?

Aletes species

Give an example of a frog genus that undergoes direct development.

Elutherodactylus species

List the different live bearing types, and briefly define them based upon the source of nutrition.

Placentotrophy - embryos receive nutrition from the placenta/placenta-like structure (this is the rarest)

Patrotrophy - embryos receive nutrition from material produced by the father (pretty rare too)

Matrotrophy - embryos receive nutrition from material produced by the mother (very common)

Lecitotrophy - embryos receive nutrition from egg yolks (MOST COMMON)

Describe the differences in viviparity in Salamandra salamandra.

They can be either matrotrophic of lecithotrophic, depending upon elevation. The matrotrophic populations give birth to neonates (fully developed young) at HIGHER elevations. The lecithotrophic populations give birth to larvae at LOWER elevations

Direct development in Urodela can be found in what subfamilies?

Plethodontini & Bolitoglossini

What type of fertilization does Gymnophiona undergo?

Internal

What is the name of the copulatory organ found in Gymnophiona?

Phallodeum

What type of viviparity do members of the Gymnophiona undergo?

Matrotrophy

Larvae feed on material produced by the oviduct

Also feed on a “slime” produced by the female

What type of teeth are found in the larvae of Gymnophiona?

Pectinate teeth (comb-shaped)

List the parental care found among Amphibians.

Nest or egg attendance

Nest or egg guarding

Egg, larval, or hatchling transport

Egg brooding

Feeding young

Guarding young

Define trophic eggs.

These are fertilized or unfertilized eggs produced by a female with the sole purpose of feeding the offspring.

Significant because the young can be placed in area with less light

Ex: Strawberry Poison Dart frog

What type of fertilization is found in all the reptiles?

Internal

When it comes to GSD, XY is the ______ and ZW is the _________.

male, female

Give a family of Reptilia where the heterogametic sex is XY.

Scincidae

Give a family of Reptilia where the heterogametic sex is XXY.

Scincidae

Give a family of Reptilia where the heterogametic sex is ZW.

Geoemydidae

Give a family of Reptilia where the heterogametic sex is ZZW.

Gekkonidae, Elapidae

Temperature sex determination was first discovered in what group of Reptilia?

Turtles/testudines

List the types of TSD and briefly explain each type.

Type 1a = more males at lower temps, females at higher temps

Type 1b = more males at higher temps, females at lower temps

Type 2 = more males found at the intermediate temps, females at the extremes

What is the Charnov-Bull Model for TSD?

A model that predicts how the temperature during incubation affects the sex ratios of herps with TSD, maximizing their fitness

Ex: Jacky Dragons exhibit type 2 TSD where females are found at the extreme temps and males are fo

What is so unique about the Eastern 3 Lined skinks in Australia and their sex determination?

They exhibit TSD in nests incubated below 20 C, but above this temp they exhibit GSD

What is the relationship between clutch size and annual survival of a species?

Inverse; higher the clutch size → lower the survival

What is the relationship between size of individual eggs and clutch size?

Inverse; larger eggs → small clutch size

What is the relationship between egg/offspring size and survival?

Directly related; larger offspring can survive better

What are the 3 hypotheses to explain small clutch size?

1) Avoids the full predation of your offspring (don’t put all your eggs in one basket)

2) Allows for larger eggs → better survival

3) Microhabitat use by the female may preclude a large clutch (ex: arboreal)

Give an example of a herp with only 1-2 egg clutches.

Anolids, Gekkonids, Gymnophthalmids, and Scincids

In the study over brown anoles being ovariectomized and shame ovariectomized, why was there a difference in survival between these groups?

The ovariectomized (real) females were faster, in better condition, and had a better immune system response compared to the shame ovariectomized (faked) females.

Only ________ exhibit viviparity in Reptilia.

Squamata/squamates

Where does embryonic development occur in squamates? What about other reptiles?

It begins at fertilization

Other reptiles it begins in oviduct or after egg laying

Why might squamates prefer their specific mode of embryonic development?

Possibly due to a difference in oxygen in the oviduct between squamates and other reptiles.

Why is development in low oxygen environments not preferred among reptiles?

This leads to developmental deformities and is not efficient (very slow)

Also decreases the fitness of your offspring

What is the pleisomorphy and the most common reptilian mode of reproduction?

Oviparity