Lecture 18- Rodents Flashcards
What percentage of Australian terrestrial mammals are rodents?
22%
How many species does the order Rodentia have?
- 2300
- 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?
-Supraorder Muroidea
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?
Murinae
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
- deep ocean
What are the second wave rodent colonizers?
-genus Rattus
-Second Colonizers •Pleistocene (~1 Ma) •25+ Species •Little morphological variation •High reproductive rates
•(8-12 teats)
Who are the first wave colonizers and how do you identify them?
-old endemics
-have 4 teats
First Colonizers
•Pliocene (~5 Ma)
•160+ Species
•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
-large terrestrial
What are the characteristics of Pogonomys?
-arboreal
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
- 600-700g
What are the characteristics of the Conilurus species group?
- Australian Endemics 3 genera, 6 species, 2 recently extinct
- tree rats
- stick nest rats (build stick nests)
- rabbit rats
What are the characteristics of the Pseudomys species group?
-Australian Endemics 5 Genera, 42 species
-live everywhere
Pseudomys= biggest group in Australia
Pseudomys= everywhere except the tropics
-then Australian lemming-grass feeding
-rock rats
-hopping mouse
-short tail rats
-false mice
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?
- some are
- 29% of species are in decline
What is the situation with Leporillus apicalis and Leporillus conditor?
- Leporillus apicalis=EXTINCT
- Leporillus conditor= Extinct on mainland Captive breeding, Reintroduction, only in Franklin island now
Why does colonization lead to the diversification of species and forms?
- Ecological opportunity
- Key Innovation
- Morphological Disparity
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
What is special about the Sulawesi Paucidentomys vermidax?
Carnivore =don’t have chiseling incisors as they should
Their teeth don’t wear as much
-no molar teeth (unlike other rodents)
-this development of teeth happened in a few other species (one in the philippines)
-they are not closely related
-the water rats also not closely related
-high convergence in rats
