Modern Amphibians = Lissamphibia Urodela (Caudata) (salamanders and newts) Apoda (caecilians) Anura...

Modern Amphibians = Lissamphibia

Urodela (Caudata) (salamanders and newts)

Apoda (caecilians)

Anura (frogs and toads)

Shared derived traits of LissamphibiaTable 10-1

Pedicellate teeth

Operculum-columella complex – Transferring air waves into fluid waves and ground vibration into sound.

Levator bulbi muscle

Closed Eye

Thin skin with mucus and poison glands

Implications for physiologyand ecology

Breathing via the skin

Water through the skin – a boon and a bane

The skin as a storehouse for toxins Chapter 10.5

And warning and cryptic pigments Aposematic coloration

Apoda (Gymnophiona) Caecilians

Reduced eyes, sensory tentacles, dermal folds

Apoda ReproductionInternal fertilzation with phallodeum

Oviparous (egg guarding) or viviparous

Cloaca

Adult teeth

Baby teeth grappling

Urodele – Caudata Distribution Holarctic

Aquatic

Terrestrial

ReproductionVisual displays and olfaction

Nasolabial groove

Sexual dimorphism

Hedonic (scent) glands

Fertilization external (few) or internal(most)

Spermatophore Fire salamander - viviparous

Egg mass

Anura most diverse, most widespread Highly derived body form

Urostyle

Illia

AnuraReproduction dominated by vocalization

Expense? See textFunctions of reproductive calls?Explosive versus prolonged breeding?

Whine Chuck

Tungara frogs

Males alone – whine onlyMales with males – Whine- chuckFemales prefer whine- chuck call

Explain the pattern

External fertilization via amplexus

Function of sexual dimorphism?

Male

Female

Biphasic Lifestyle Advantages?Disadvantages?

Amphibian Conservation Issues

Cane Toads (Bufo marinus) Introduced into Australia

Conservation concerns?

Bullfrog (Rana catesbiana) introductions

Major Conservation Concern: Amphibian Declines

2006 report:

1,856 species, 32.5 percent of the known species of amphibians, are “globally threatened,” (vulnerable, endangered or critically endangered). By comparison, 12 percent of bird species and 23 percent of mammal species are threatened.

435 amphibian species are in rapid decline, at least 9 species have gone extinct since 1980 and another 113 species have not been reported from the wild in recent years and are considered to be possibly extinct.

Causes?

Amphibian characteristics that increase susceptibility to environmental changes??

Habitat Loss

Over-exploitation as:

Food

Pets - Goliath frog

6 million into Hong Kong/yr

Introduced Species

99% of lakes in Sierra Nevada originally without trout.

Rana mucosa (native frog) declining in part due to trout predation

Amphibian egg survival and ultraviolet light at high elevations

Rana

Hyla

Bufo

UV protected No UV protection

Increased ultraviolet radiation due to reduced ozone

Worldwide studies of UV on amphibiansRed = negative effect of UV

PollutantsNitrogen, pesticides, acidification,

Deformities

Trematodes parasites cause abnormalities

Eggs

Meracidium

Cercaria

Cysts

Chytrid Fungus

Global Climate Change?

Direct: Loren’s paper

Interaction with: disease susceptibility to toxinssusceptibility to parasites

Species Introduction?