BIOC51H3 Lecture 4: BGYB51H3 Lecture 4 Notes Sep 22
11 Aug 2010
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BGYB51H3 Lecture 4 Notes
-dispersion is a very rare event and the continents are the sources of the ancestors of
organisms on the nearby island
-organisms on the island adapt to new conditions on the island and evolve to new species
-on an island, there are many empty niches that need to be filled, which causes adaptive
radiation
-adaptive radiation splits lineages and makes some species endemic
-seed dispersal to islands causes plants on islands that are endemic due to adaptive radiation
-endemism is more common for species with low dispersal (e.g. plants)
-an archipelago is a group of islands formed by volcanic eruptions
-Hawaiian islands are different ages due to different eruption times
-in the archipelago, species are different on each island but similar between neighbouring
islands
-environments modify structures of organisms even though building blocks may be similar as
well as embryonic formation
-the same tissues give rise to similar structures in similar relative positions
-transition forms show development of two different lineages
-structures can be repurposed through natural selection
-new lineages may become more refined than their transitional formed parents
-functional structures show little evidence compared to non-functional structures (vestigial
structures)
-inherited structures may acquire new functions in descendants (homologous traits)
-natural selection involves structures that work built on pre-existing ones
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Document Summary
Dispersion is a very rare event and the continents are the sources of the ancestors of organisms on the nearby island. Organisms on the island adapt to new conditions on the island and evolve to new species. On an island, there are many empty niches that need to be filled, which causes adaptive radiation. Adaptive radiation splits lineages and makes some species endemic. Seed dispersal to islands causes plants on islands that are endemic due to adaptive radiation. Endemism is more common for species with low dispersal (e. g. plants) An archipelago is a group of islands formed by volcanic eruptions. Hawaiian islands are different ages due to different eruption times. In the archipelago, species are different on each island but similar between neighbouring islands. Environments modify structures of organisms even though building blocks may be similar as well as embryonic formation. The same tissues give rise to similar structures in similar relative positions.
