Lecture 10- Amphibians 2 Flashcards
What is the distribution of the family Bufonidae?
-“true toads” -common everywhere else except Australia -1 genus and 1 species, introduced -Can toad, Bufo marinus
What are the eggs of frogs like?
- encased in jelly which swells with water soon after laying - embryos are black if eggs are exposed to sunlight – to protect them from UV - size of the eggs varies dramatically across species (less than 1mm to half a centimetre) –depends where they live, parental care
Where do frogs deposit their eggs?
-freely floating in ponds -floating in foam nests (protects them from predators, temperature control) -in nests under rocks or on banks of streams (predators protection) -terrestrial nests (still have to be moist, also protection from predators) -or in stomachs and pouches
What happens in direct development/delayed emergence?
- increased size of individual eggs - reduction in number of eggs laid (no more than 50) - often parental care of some sort - often hidden away - often a tougher outer capsule
What is special about the Marsupial frog, Assa darlingtoni?
-unique species -eggs laid on land, males remain nearby -tadpoles hatch and swim up male’s flanks and into the pouches - 8-50 eggs laid, but only a few make it the into the pouch male becomes covered with egg jelly when the eggs hatch - hatch at 11 days, emerge about 2 months later -tadpoles white as not exposed to sunlight
What is special about the gastric brooding frogs, Rheobatrachus?
-Habitat: boulder-strewn, fast-flowing streams in rainforest –extinct 1985 and 1981 (2 species) only discovered in the 1970s -large eggs (5 mm) - laying, fertilizing and swallowing of eggs never observed - females can lay up to 40 eggs but max of 26 observed in the stomach - white tadpoles - development at least 6 weeks - “females disgorged their entire complement of young by the simple act of propulsive vomiting” - female’s stomach seems typical of other frogs - prostaglandin E2 is secreted by the tadpoles and stops acid and pepsin production in stomach, as well as peristalsis
What are the limitations using ancient DNA?
• Limitations to using ancient DNA • Degraded, fragmented, fixation method • Specialised procedures • Low DNA lab, body suit, replication
What does habitat fragmentation do?
• limit gene flow between populations - reduced potential to adapt to future conditions - inbreeding depression
What is the impact of climate change on the beautiful Nursery Frog?
-Beautiful Nursery Frog Cophixalis concinnus -only lives on thornton’s peak (1000m and above) -if temp changes by 1 degree= the lower boundary of it will go extinct -live in crevices
