Wildlife Diseases 2.7

What happened to the harlequin frogs in Central America?

These frogs (genus Atelopus) were brightly colored, poison-dart-frog mimics. Once abundant, they vanished within ~2 years due to chytrid fungus, and were thought extinct.

What is chytridiomycosis and what causes it?

A skin-infecting fungal disease in amphibians caused by Batrachochytrium dendrobatidis (Bd).

Why does Bd kill amphibians?

The fungus attacks keratinized skin, disrupting respiration and osmoregulation, eventually causing cardiac arrest.

How does climate change worsen chytrid outbreaks?

Alters rainfall → drought → frogs crowd in small pools → higher spore concentration; warming may create ideal Bd temperatures.

What species likely helped spread chytrid globally?

African clawed frog (Xenopus laevis). Used in the 1950s-70s as pregnancy tests; global trade likely moved Bd worldwide.

Why is Central America important to chytrid history?

Massive, well-documented Bd outbreaks starting in 1987 caused many amphibian extinctions; dirty boots/gear may have spread spores between sites.

Name an amphibian lost to Bd in Costa Rica.

Golden toad (Incilius periglenes)—declared extinct in late 1980s due to chytrid.

What frog was saved through captive programs?

Panamanian golden frog (Atelopus zeteki); rescued before Bd reached its final refuge.

Why are diseases considered invasive in conservation?

They often arrive from outside regions and attack immunologically unprepared native wildlife.

What causes white-nose syndrome in bats?

Fungus Pseudogymnoascus destructans.

How does white-nose syndrome cause mortality?

Fungus irritates hibernating bats → wakes them → increases metabolism → starvation due to lack of winter food.

Give a bat species heavily impacted by white-nose syndrome.

Little brown bat (Myotis lucifugus).

Why are bats vital economically?

Insect control saves U.S. farmers ~$3.7 billion annually in crop damage prevention.

Why is bat recovery so slow after disease?

Most temperate bat species produce one pup per year, slowing population rebound.

What spreads avian malaria in Hawaii?

Mosquito Culex quinquefasciatus.Infects native Hawaiian honeycreepers (Family: Fringillidae).

Why are high-elevation Hawaiian birds safer?

Mosquitoes cannot survive cold volcanic slopes—higher elevation = disease refuge.

How is climate change worsening avian malaria?

Warmer temperatures let mosquitoes move upslope into formerly safe high-elevation refuges.

Why aren't diseases the sole threat?

They interact with habitat loss, climate change, fragmentation, pollution, low genetic diversity → creating an extinction vortex.

What is an extinction vortex?

A self-reinforcing cycle where small, isolated populations lose genetic diversity, become less adaptable, face higher impacts from threats like disease or environmental change, and decline even faster—driving them toward extinction.

What are "Lazarus species" in amphibian declines?

Species believed extinct but later rediscovered—often isolated survivors with genetic resistance (e.g., rediscovered Atelopus spp.)

Name other significant diseases impacting wildlife.

White-nose syndrome (bats)

Avian malaria (Hawaiian birds)

Chronic wasting disease (deer/elk; prions)

Brucellosis (bison Bison bison; livestock origin)

Yellow fever impacts: howler monkeys (Alouatta spp.)

How did yellow fever affect South American howler monkeys?

Caused mass die-offs in the Atlantic Forest; species like the brown howler monkey (Alouatta guariba) nearly vanished from some regions

How do humans unintentionally spread wildlife diseases?

Dirty boots/gear, international travel, pet trade, wildlife handling, livestock interactions.

What are key conservation strategies against wildlife diseases?

Monitoring, early detection, habitat connectivity, captive assurance colonies, management of trade, international cooperation.

Why can't countries manage wildlife diseases alone?

Pathogens cross borders; require shared research, funding, policy alignment, and coordinated monitoring.