Distributions, Migration And Dispersal Flashcards
When did the first mammals appear
Triassic, they were egg laying
When did modern mammals (placentals, marsupials) evolve?
100mya, late Cretaceous
What are some of the wandering families?
Shrews, dogs, cats, mustelids, bovids
When did angiosperms (flowering plants) arise?
130mya, modern angiosperms around 95mya
How many species of flowering plants are there?
300,000
What are the advantages of angiosperms?
- tough leathery leaves, drought resistant
- resistant seed coat prevents desiccation
- efficient water conducting vessels
- fast speciation rates
Why did angiosperms diversify so quickly?
Because of insect-angiosperm evolution
What are cosmopolitan taxa?
Taxa that occur in all/most regions of the world
Few truly cosmopolitan (humans)
House sparrow in most, migrated with humans
Give examples of wide spread taxa (in suitable habitats)
Penguins - cold lower latitudes
Heather - western oceanic Europe
Cacti - north central and South America
An example of a disjunct taxa?
Marsupials, abundant in Australia, but some many 1000s km away in S America
What are endemic species?
Species found only in one well defined region
Eg. Finches found on individual islands of Galapagos
red grouse, Britain
Greater similarity in plants of S America, Africa, Oriental, Australia than mammals, why?
- Plants evolved and dispersed earlier than mammals
- More extinction of mammals
- Greater modern dispersal ability of plants
Climatic relicts, give an example
The arctic spring tail,
Arctic springtail - 2x8 eyelets
Pyrenees springtail - 2x6 eyelets
Why is plant dispersal so successful?
- Seeds are v resistant
- Self fertile, one seed can be successful
- Ariel dispersal
- Primary producers, self sufficient
Animal dispersal, why easy but why not easy?
Easy - mobile - potentially rapid migration eg. Starling from New York to Canada in 50years
Hard - most animals need 2 individuals of opposite sex to breed
Many insects have 1 single food source
May carry parasites and diseases
