Herp Repro

Gametogenesis and Fertilization (egg structure) Amphib vs Rep

R- more energy (^yolk) and protection (shell) but fewer babies

Membranes of amniotic egg (3)

1) Chorion = Surrounds everything

2) Amnion = Fluid-filled + Surrounds embryo

3) Allantois = Respiratory surface for embryo + store nitrogenous waste

Reptile Eggs Upper part of oviduct + egg shell permeability

Oviduct: Egg coated with albumin

-Crocs and squamate fibers = calcite crystals

-turtles fibers = aragonite crystals

Shell: Low amino acid levels (especially Proline) = ^ resistance to drying out (desiccation)

Direct vs indirect development

D= lots of yolk + embryos > mini adults

I= little yolks + embryos > feeding larvae

• amphibians and inverts

• rapid change in body form aka Metamorphosis

Alternatives to Direct vs indirect development (Caecilians + Salamanders + Frogs)

Caecilians

• Direct development + Viviparity (feed on skin of mother)

Salamanders

• Plethodontids = large terrestrial eggs + direct development

• Paedomorphosis = adults with larval traits + evolved independently

Frog tadpoles

• develop away from water with ^ parental care

• develop in weird places like Bromeliads

• don’t feed

• Direct Development

Example of Alternatives to Direct vs indirect development (frog)

Bromiliad tree frog

Mating Behaviors (Amplexus, coplexus, copulation)

Amplexus - external fertilization common in amphibians

Coplexus - Intromittent organ (like tail) deposits sperm inside cloaca of female

Copulation - Internal fertilization common in reptiles

Sperm storage

spermatophore

package containing sperm left by male salamanders for females to pick up with cloaca lips

elaborate courtship

External Fertilization

Most Frogs, all Cryptobranchids and Sirens

No intromittent organ

Amplexus

Internal Fertilization

Intromittent organ - reptiles + caecilians + tailed frogs

Cloacal Apposition - tuatara

Spermatophores - most salamanders

Coplexus

Spermatophores

Made by Males and females pick it up with lips of cloaca

Proteinaceous Pedicel with Sperm Packet

Elaborate courtship

Sperm Storage for salamanders turtles and squamates

• Salamanders – Spermatheca on roof of cloaca, females can pick up multiple Spermatophores

• Turtles – middle/upper oviducts

• Squamates – lower oviduct

Sperm Storage benefits

Internal Fertilization can be immediate or delayed

Opportunities for Multiple Paternity + Colonization

Nests - Amphibians

Discrete structures built for reproductive reasons

Unusual/ uncommon

Eggs deposited in water or land

Foam Nests

Leptodactylidae, Myobatrachidae, Rhacophoridae

water or land

Tadpoles drop into water or washed in during rains

for that calls from entrance of Leaf-cutter ant nests and Builds foam nests inside flooded underground ant chambers

Craugastoridae

Craugastor lineatus

frogs that construct water-filled basins that isolate eggs from streambed

Gladiator Frogs

hylidae

Underground nests near water (2)

Leptopelis – Arthroleptidae (Some lay eggs underground)

Hemisus – Hemisotidae (Shovelnose Frogs - Fossorial + female
burrows to water)

Nests - Reptiles

Most construct nests

aboveground nests + Eggs are guarded + Hatchlings assisted by mother + Vocal communications

who am I?

Crocodilians

Nest defenders

Amphibians

squamates

crocodiles

dig nests in sand or soil and do not attend nests often in alligator nests/ ant or termite mounds who am i?

Turtles

turtle where females guard eggs

Kinosternon flavescens

Podocnemis expansa (Giant Amazon River Turtle)

turtle with underwater eggs

Chelodina rugosa

Nest Site Selection

fitness

Reptiles = mortality is highest in egg stage

Appropriate biophysical environment(temperature, moisture, pH)

protect from predation

Incubation Temperature and short vs long Incubation

(graph)

Shorter incubation = reduces risk of predation + changing biophysical
conditions

longer incubation = more developed hatchling

Hotter nests developed faster + Cooler nests had higher hatchling success, larger initial size, faster growth, and faster sprint temperatures

Common Wall Lizard

Fall Emergence – Temperate Zone

Reptiles breed in Spring + hatchling emergence in Fall

Resources are declining when emerge = race to acquire nutrients for winter survival

highest stages of mortality 

1) egg

2) neonate (predation, freezing, starving)

turtles Overwintering in Nest

painted turtles

Sonoran mud turtles

• Male Heterogamety – (xx/xy) example amphibs

Salamandridae

Plethodontidae

• Female Heterogamety – (zz/zw) amphibs

Sirenidae

Plethodontidae

Reptiles – Genetic or Temperature-Dependent Sex
Determination

M+F Heterogamety

Heterogamety (vv) (turtles and squamate)

Temp dependant (everything except snakes)

Variation within families

Male heterogamety

Female heterogamety

Temperature-dependent

Geoemydidae

Ancestral Condition in Sauropods

Genetic Sex Determination

TS

evolved several times

lost several times

ancestral in Turtles and Lepidosaurs

(gsd>tad>gsd again)

Multiple Factors Determine Phenotype

• Genetic Factors

• Maternal Factors (Nest site choice + Yolk steroids)

• Environmental Factors (nest temp)

Climate Change and TSD

could bias sex ratios

observed in American Alligators and Loggerhead Sea Turtles and tuatara

Number and Size of Offspring -
Interspecific

Many small eggs vs. few large eggs

Bufonids – thousands of tiny aquatic eggs

Dendrobatids – a few large terrestrial eggs

Number and Size of Offspring -
Intraspecific

Sand Lizard (Lacertidae)

Body Size/Clutch Size relationship Clutch size increases with body condition (mass/length)

Australian Water Python – Liasis fuscus

Body Size/Clutch Size relationship Multiple clutches per year

Australian Keelback Snake – Tropidonophis mairii

Large offspring hatch earlier

and metamorphose at a larger size

Body Size/Clutch Size relationship

Ambystoma talpoideum

salamander Breeds annually vs biennially

Plethodon websteri (Georgia)

• Breeds annually

• Plethodon kentucki (Kentucky)

• Breeds biennially

Dissociated Hormone
Production and Mating
Behavior

Lined Snake

Seasonality

• Tropical Australian Crocodiles

Freshwater Crocodile (Crocodylus johnsoni) – dry season nests

Saltwater Crocodile (Crocodylus porosus) – wet season nest

Reproductive Productivity - Most significant of the variables

environment temp

Surgically remove eggs or ovaries from
experimental females + ^ survival

Anolis sagrei

• Oviparous, Single-brooded species

• Viviparous, Annually breeding species

• Viviparous, Biennially breeding species

snakes

• Oviparous, Single-brooded species

Colubrids

• Viviparous, Annually breeding species

Elapids

• Viviparous, Biennially breeding species

Viperids