Lectures 5- Reptiles 2 Flashcards
How is Australia reptile’s paradise?
-high endemism: number of species unique to a specific area -high species diversity: total number of species found in an area -lot of endemic species is indicative of how suited that environment to those types of animals
What is allopatric speciation?
original population- then a physical barrier results in genetic differentiation - evolution of reproductive isolation and eventually sibling species that cannot interbreed -species evolved in isolation -like a river
What is peripatric speciation?
.have original population- new niche entered and this results in genetic differentiation- then they can no longer interbreed -the species develop in isolated niche
What is parapatric speciation?
-have original population then some individuals enter a new niche that is accessible -genetic differentiation and can’t interbreed -the species develop in contiguous niche
What is sympatric speciation?
-original population-genetic polymorphism-inbreeding by mutants- species evolved in shared space
What drives spatial variation in reptile diversity?
-patterns in local species across geographic space are a function of environmental heterogeneity, speciation, extinction and colonization -biogeographic history (extinction episodes due to habitat contraction) -physiological preferences and tolerances (temperature, rainfall, climatic stability) -biotic interactions (competition and predation) -disturbance= fires and cyclones -basically there are different numbers of species in different places
What are the areas of high reptile endemism and species richness?
-Kimberley= desert areas separate the places with lot of life so hard to travel in between and they can evolve in isolation -wet tropics(Daintree)= generate lot of diversity as there are mountains
What percentage of reptiles species lives in the wet tropics?
-23%
Are deserts diverse in terms of species?
-deserts can also carry high species diversity -highest diversity in central western australian desert
What is the explanation for the difference in elapids diversity in Australia?
-all snakes in victoria= venomous -if lot of resources and possible prey then lot of snakes -that is why more in the north -more snakes in the wet tropics than in the colder zones
What are the three dangers to snakes in terms of extinction?
-anthropogenic global change can have negative consequences for reptile -=via habitat loos/alteration, invasive species
How many reptilian species have gone extinct in Australia?
-none so far but many at danger -4 critically endangered -900 types of reptiles in Australia -critically endangered= most at danger =western swamp tortoise -to breed, drop their eggs into dry swamp, then rain comes and the eggs start developing at contact with water. =global change and habitat loss makes the rain unlikely= thus the eggs don’t develop
What are the three types of habitat alteration and their effects?
1.Habitat loss- big danger, leads to death in whole populations 2.Fragmentation= small forest left alone becaus eof fields, then the populations are isolated and find it hard to move in between habitat patches 3.Disturbance= when managing for resources -like logging
How do reptiles respond to disturbance? -like fragmentation of a forest
-small skink= disturbance is good for it= the predators have probably disappeared from that patch gekko= slow decline, maybe moisture change, take slonger to take effect python=predator, probably not enough food, steep decline
What is the story of the pygmy blue- tongue ?
-thought to have been extinct in 1959 -rediscovered in 1992 in a roadkill corpse of a brown snake
What is the impact of cane toads on reptilian populations?
-cane toads= the worst -spread thousands of kilometers away from the place of release -they have poisonous glands= so most species that try to eat them, die -when invasion in a place you’d see loads of dead crocodiles etc.= decline in croc numbers -cane toads are the worst to goannas, very steep decline in populations, get big crushes of pop. why do some survive? not sure…
Why are cats and foxes a problem for goannas?
-competition! -cats and foxes and goannas all go for ringtail possums (63% for goannas and about the same for fox and less for cat) -the impact on goannas is decline in population numbers
Why are reptiles important for aboriginals?
-major food source esp. goannas, turtles(also social status, hunters= more kids) -spiritual beliefs
What was the Megalania prisca?
-ancient giant lizard -5.5 meters, 620kg -disappeared about 40 000 years ago -the Aboriginals were in Australia when they were alive
How did white people exploit reptiles?
-Turtle soup - 1870-1973 -crocodiles…
