Cheat Deck Flashcards
Who came up with the theory of island biogeography equilibrium?
MacArthur and Wilson 1967
What is MacAuthur and Wilson’s theory of island biogeography 1967
Current island populations reflect the balance between colonisation and extinction rates.
If a new volcanic island were to rise out of the ocean off the coast of a mainland inhabited by 100 species of birds, some birds would begin to immigrate across the gap and establish populations on the island.
The rate of immigration would decline, as would the rate of extinction, reaching an equilibrium.
MACARTHUR AND WILSON 1967
What is island biogeography?
Provides some of the best evidence in support of natural selection and the theory of evolution.
Describes an ecosystem that is isolated by being surrounded by different ecosystems.
What is Wallaces line? (1859)
- Wallace studied the islands of Bali and Lombok and noted that they had similar climate and size and were 30km apart.
- However, Bali has tigers, monkeys and bears and Lombok has birds of paradise, very different taxa.
- They’ve never been joined and fast currents run between the islands as a biogeographic barrier.
- Bali is continental and Lombok is oceanic which explains why there are only birds on Lombok as it’s easier to disperse.
WALLACE 1859
What is island dwarfism?
The process of large animals evolving and reducing body size when population range is limited to a small environment. This is caused by a niche of resources, causing stunted growth and reduced reproduction.`
Example of dwarfism?
Channel Island Fox (Urocyon Littoralis):
- One third smaller than its mainland ancestor the gray fox.
- Decline in 1990’s was attributed to predation by golden eagles which inhabited island after alien prey base (feral pigs and mule deer fawns) along with absence of native bald eagle due to extirpation via chemical contaminants and direct persecution.
- Also declined due to canine distemper virus caused by a mainland raccoon (Coonan et al. 2010)
- Due to being geographically isolated, it has no immunity to parasites and diseases brought in from the mainland.
- Solution: USFWS draft recovery plan inn 2012 to remove disease and predation using monitoring strategies and managing captive fox populations.
What is island gigantism?
Size of a species grows rapidly in comparison to mainland species, due to the absence of predators, size is used for competitive resources.Can withstand harsher conditions
What is Foster’s island rule? 1964
Members of a species get smaller or bigger depending on the resources available in the environment
FOSTER 1964
Example of gigantism?
Giant rat (Papagomys Amandvillei), Flores (Indonesia):
- Due to smaller landmass and limited food resources as well as absence of predators such as hawks falcons and owls as the predators on Flores are kimodo dragons, marabou stork and vultures, meaning rats had no reason to remain small
- IUCN Red List, near threatened threatened by deforestation, dogs and cat predation and hunting from locals.
- Solution = Rutong Protection Forest
(Suyanto 1998)
What is speciation?
NOT the process of natural/genetic factors.
Caused by underlying biogeographic processes of isolating barriers, preventing gene flow.
What is allopatric speciation?
Also called geographic speciation, occurs when populations become isolated which disrupts gene flow
Allopatrically formed species are post zygotically isolated - even when they can interbreed they are incapable of producing a fertile, hybrid offspring.
ISOLATED AND EVOLVE DIFFERENTLY
(Cabej, 2012.)
What is sympatric speciation?
Occurs when two groups of the same species live in the same geographic location, but they evolve differently until they can no longer interbreed and are considered different species.
TOGETHER BUT EVOLVE DIFFERENTLY
(Feder - 2002)
What is parapatric speciation?
In parapatric speciation there is no specific extrinsic barrier to gene flow. The population is continuous, but nonetheless, the population does not mate randomly. Individuals are more likely to mate with their geographic neighbors than with individuals in a different part of the population’s range resulting in reduced gene flow.
TOGETHER BUT CHOOSE NOT TO INTERACT
(Gao and Harris 2019)
What is peripatric speciation?
Similar to allopatric in which populations become isolated however, happens when one of the isolated populations has very few individuals.
ISOLATED BUT ONE HAS SMALL POPULATION
(Valtuena et al. 2017)
What is ecological succession?
Ecological succession is the process of change in the species structure of an ecological community over time. Generally begins after disturbance creates a situation of great resource availability that can be exploited by organisms, but under conditions of little competition.
