Flashcards in Lecture 18- Rodents Deck (25)
What percentage of Australian terrestrial mammals are rodents?
How many species does the order Rodentia have?
-45% of all mammals
When did rodents evolve?
-65 MYA (mammals 195 MYA)
What are the key features of rodents?
-molariform teeth (premolars and molars)= squarish teeth for grinding
-diastema= gap between incisors and premolars
-incisors (continuously growing and large)
What is the weight range of rodents?
-4g (pygmy jerboa) to 66kg (capybara)
What order are rats and mice etc. in?
What are the two main orders of rats and mice (Muroidea)?
-1 Murinae (620+ species, 11% of mammals, origin 12 MYA)
2. Sigmodontinae (380+ species, 7% of mammals)
How did rodents get to Australia?
-crossed into Australia twice
-once 5 million yrs ago and then more recent (1 million yrs ago)
-from Asia (and PNG)
What order are all the rodents in Australia?
What is the Wallace's line?
-Wallace’s line= because the land masses were never connected in the last 10 million years, that is why different animals on each side
What are the second wave rodent colonizers?
-Second Colonizers •Pleistocene (~1 Ma) •25+ Species •Little morphological variation •High reproductive rates
Who are the first wave colonizers and how do you identify them?
-have 4 teats
•Pliocene (~5 Ma)
•Large ecological and morphological variation
•Low reproductive rates •(4 teats)
What are the characteristics of the Anisomyni?
New Guinea Endemics 12 genera Australia 1 genus, 1 species
What are the characteristics of Pogonomys?
What are the characteristics of Hydromini?
-the aquatic and terrestrial carnivores
-10 genera Australasia Australia 2 genera, 2 species
What are the characteristics of the Uromyini?
Generalized ‘rats’ 4 genera Australasia Australia 2 genera, 6 species
-live in wet tropics rainforest
-the other live in rainforest, grasslands and monsoon tropics
What are the characteristics of the Conilurus species group?
-Australian Endemics 3 genera, 6 species, 2 recently extinct
-stick nest rats (build stick nests)
What are the characteristics of the Pseudomys species group?
-Australian Endemics 5 Genera, 42 species
Pseudomys= biggest group in Australia
Pseudomys= everywhere except the tropics
-then Australian lemming-grass feeding
-short tail rats
How many species are there in the genus Rattus?
7 species (+2 extinct from Christmas Island) 18+ species New Guinea
--bush rat= one of the most widespread
Why is there so much diversity in rodents? (Muronia)
-adaptable, live in diverse habitats,diversify in form as they colonize
-hopping mice = in American and Australia=== developed independently
-converge in having one of the most efficient kidney= never need to drink water, get it from break down of fats
Are rodents declining in Australia?
-29% of species are in decline
What is the situation with Leporillus apicalis and Leporillus conditor?
-Leporillus conditor= Extinct on mainland Captive breeding, Reintroduction, only in Franklin island now
Why does colonization lead to the diversification of species and forms?
What is the story with the Australian stick nest rat and the American Wood Rat?
-both build stick nests
-stick nest rats= build stick nets to protect from carnivores
-wood rats= independently developed wood nests that are passed down the generations and protect them