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Lecture 1

BIOL 215 Lecture Notes - Lecture 1: Gymnosperm


Department
Biology (Sci)
Course Code
BIOL 215
Professor
Neil Price
Lecture
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BIOL-215 – Lecture 6
Professor Gemma DeMartino
September 18, 2014
RADIATION
Announcements:
Tutorials start next week
You should read the assignment and try to answer the questions before going to the
tutorials
EVO-DEVO research at McGill:
Dr. Hans Larsson (Redpath Museum) : works primarily on reptiles and birds
Dr. Ehab Abouheif (Stewart Biology) : works on how ants diversify
From previous class:
The study of evolution is the history of life on the planet
Takes into account the relationship between living organisms, the classes and extinct
groups
Molecular data and Fossil record are both used to date the emergence of organisms
Multicellularity happened many times during the course of evolution
Need to know different mechanisms/examples of multicellular inventions (ex. volvox)
On the Agenda:
Take a tour of the radiations of the history of life
Examination of the cambrian radiation in detail in detail
Chapters 11, 18 – Evolution (Hall, 2011)
Lecture Objectives:
Understand the definition of adaptive radiation and observe the radiations that occurred
after mass extinctions
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BIOL-215 – Lecture 6
Professor Gemma DeMartino
September 18, 2014
Understand the main reasons for the Cambrian explosion, and why organisms after this
time diversified so quickly
This includes the elaboration of genes such as the homeobox genes, which pattern animal
bodies, and that originated before animals, plants and fungi arose.
Geological time scale
Of the 1.2 billion years of animal evolution, Modern humans have been on the planet
only 200000 years
Evolutionary invention can cause adaptive radiations
Adaptive radiation: evolutionary divergence of members of a single phylogenic lineage
into a variety of different adaptive forms over a relatively short interval of geological
time
Adaptive radiations are usually given by key innovations; a change in morphology that
allows the lineage to diversify very fast
In order for the organism to acquire other properties: exploring different habitats, being
more resistant to a predator
Lead the lineages to diversify very fast (phylogenic tree)
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BIOL-215 – Lecture 6
Professor Gemma DeMartino
September 18, 2014
Clade A is normal sepeciation - Clade B is an example of adaptive radiation
Ex: flowers, the feather, molars – explore new environments/foods/niches
How/why adaptive radiations?
Fill previously unavailable niches – due to mass extinction
Competitive release: once they fill other niches, they cease to compete in the same way
they did before; release of the competition for some resources
Competitive advantage: opening up new niches that were previously unfilled
Mass Extinctions:
The loss of species from many different groups - it takes large numbers of species
(sometimes up to 96%)
They occur infrequently and abruptly over short periods of geological time
There are 5 great mass extinctions during the history of animal and plant life
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