Class Notes (835,241)
Canada (509,043)
ENV200H1 (60)
Karen Ing (49)
Lecture 11

ENV 200 Feb 28 lecture 11.docx

2 Pages
77 Views
Unlock Document

Department
School of Environment
Course
ENV200H1
Professor
Karen Ing
Semester
Winter

Description
ENV 200 Feb 28 lecture 11  Evolution: o Imagine a situation where 2 species of warblers “compete” for insects on a spruce tree (ex: spending time and energy chasing each other from a certain place in the tree) o Now imagine a behavioural change (likely driven by a random mutation) by which some individuals move to a unique area of the tree to feed o Now the warbler neither has to chase away others (or be chased) it has more time to gather insects than individuals who are still competing o With more energy available to devote to reproduction, it raises more chicks than the individuals who are still competing o Overtime, long time, the population will come to be dominated by the individuals with the unique feeding behaviour o Over time in reasonable stable/predictable envs populations are expected to exhibit progressively narrower realized niches ex: to become more specialized  In the early days of life on earth... o Resources would have been abundant o Populations would have grown rapidly o But as populations began to approach carrying capacity, competition for resources would have increased o Any heritable adaptation or element that would confer an adv with respect to obtaining/using resources would have been selected for (adaptive)  Evolution: natural selection o This is a simple concept, but astonishingly powerful o All the organism on Earth (living or fossil) came about through evolution o Individuals with various traits that promote reproduction (and the number of offspring produced) will come to dominate the population over time o Individuals w/o these adaptations will disappear (eventually) o This is what we mean by survival of the fittest  Where fitness is defined by the number of offspring particular individuals put into the next generation o Since fitness is defined as the number of offspring a particular individual produces any adaptation that improves fitness will be selected for as long as it is not accompanied by negative implications  Ex: we also see adaptations to attract a mate for animals or attract pollinator and disperse seeds in plants  Role of Genetics o Adaptations had to be heritable (passed on to the next generation) o The mechanism how “heritability” worked was not understood until the 1950s when Watson and crick proposed the structure for Dna o Since adaptation have to be heritable they have to be coded for by dna  DNA: deoxyribonucleic acid is double stranded  Two strands are held together by bonds between the nucleic acid rungs  There are only four nuc
More Less

Related notes for ENV200H1

Log In


OR

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


OR

By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.


Submit