Animals in the Anthropocene II: The case of amphibians

Amphibian ecological roles

• Key environmental indicators: Ecosystem health indicators due to their sensitivity to environmental changes.

• Crucial Ecological Roles: Dual roles in food webs as predators and prey, contributes to ecological balance and offering vital ecosystem services i.e. pest control

• Diversity and Vulnerability: Amphibians have specific habitat needs and narrow preferences make them particularly vulnerable to rapid environmental changes.

Origins

• Ancestor with lobe-finned fishes

• Key evolutionary adaptions: development of lungs, limbs and the ability to live both in water and on land.

• Survived the Permian Extinction ‘‘Great Dying’’ of anoxia, OA and warming.

• Tiktaalik roseae. “Fishapod” 375 MYa

  Lepospondyli - Diplocaulus. Late Carboniferous

  300MYa

Clades

Anura

Example: for unique adaptions

Skin and gastric brooding

Sexual selection and displays

Aposematism*

Caudata

• Some salamander speices are arboreal

• May possess Tetrodotoxin

• Facultative paedomorphosis

  • Adults retain larval characteristics

  • In stable habitats that don’t require migration

Gymnophiona

• Skull adapted for subterranean lifestyle

• Little known, it’s difficult to find them

• Some species provide parental care

• Oviparous species

  • Skin feeding

  • Milk provisioning

• Viviparous species

  • Oviduct lining feeding

Morphological diversity

Amphibians are very diverse

• Sizes

• Calls

• Colors

• Behaviours such as gliding

Distribution

• Globally distributed but absent in Antarctica

• Over 8,600 amphibian species

• Common in humid tropical environments

• Some adapt to extremes, from deserts to Arctic tundras

Amphibian respiratory adaptions

• Three types of respiration

  • Cutaneous

  • Buccopharyneal

  • Pulmonary (paired lungs)

• Tadpoles, lungless and paedomorphic salamanders & during hibernation: cutaneous only

Amphibian reproduction

• Aquactic vs terrestrial egg deposition

• Egg-laying vs direct development (29%)

• Diverse parental care

  • Tadpole transport

  • Guarding

  • Mosturising clutch

Amphibian physiological adaptions

• Nocturnal activity

  • conserve moisture

  • low metabolic rate

• Hibernation and estivation

  • Freeze tolerance

• Lung loss in plethodontids*

  • embryos initally develop lung rudiments, which regress through apoptosis*

Amphibian decline

1. Habitat destruction and fragmentation

2. Disease, specifically chytridiomycosis

3. Climate change impacts

4. Pollution and pesticides

5. Invasive species

Threats to Amphibians

• 1985: Dr. Karen Lips studies tree frog ecology in Costa Rican cloud forest.

• 1996 return: Found all frogs disappeared from the site, similar disappearances in a western site

  Suspected an unknown disease might be the cause of disappearances, prompting further investigation westward

• Arrival in Panama: Found frogs initially present

• Observed frogs dying rapidly in the following days

• Dr. Joyce Longcore determined deaths were due to Chytridiomycosis (Bd), new fungal disease

Threats to Amphibians 2 (salamanders)

• Bd declines in frog slowly

• New disease since 2010s: Bsal Batrachochytrium salamandrivorans

• Affects salamanders in Europe

• Spreading rapidly, assessments are underway

Threats to Amphibians 3

Global and local initiatives (conservation)

• Global and local conservation initiatives

• Combating disease

• Captive breeding and reintroduction programme

• Habitat restoration and protection

• Citizen science and community involvement

The impact of amphibian conservation

GAA2 Conservation priorities 1

• Global monitoring needed

• Expand habitat protection, especially at high elevation to provide migration buffers and corridors

• Conservation breeding programmes

• Active management of protected areas

Madagascar

Development index:

• Country rank 142 of 176

• Severe deforestation

• High amphibian endemism and species richness

• Where do which species occur?

  • Microendemism

• Which areas to conserve?

Madagascar images