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Lecture 4

BGYB51H3 Lecture 4 Notes Sep 22

Biological Sciences
Course Code
Maydianne Andrade

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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
-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
-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
-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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