Download Natural selection and adaptation - Powerpoint for Sept. 16.

Evolutionary Ecology
Species Numbers - 2012
What’s missing?
A new phylogeny –
without prokaryotes
From Wilson,
1992
Bird Adaptations
Evolution
• Evolution simply means change and
biological evolution can be defined as
changes in any attribute of a population
over time
• Evolutionary changes that lead to adaptation
must involve a change in the frequency of
individual genes in a population from
generation to generation
Parus caeruleus
Adaptation – process which leads to
survival and reproduction of
characteristics beneficial to an organism
in a particular environment
Perfect Adaptation? Hmm…
Charles Darwin
Age 46
Alfred Russel
Wallace –
in his 70’s
Evolution by Natural Selection
1. Individuals in a population of a species are not identical.
2. At least some of this variation is heritable.
3. All populations have very high reproductive potential, but
they seldom achieve it. Mortality and less than maximum
reproductive rate keeps them from taking over the earth e.g. oysters
4. Different individuals leave different numbers of
descendents. - this is where idea of fitness comes in
5. The number of descendents an individual has, depends on
the interaction between the characteristics of the individual
and its environment.
Two major points about natural selection
1. Variation among individuals arises due to
chance mutations.
2. Individuals survive in today's environment
because it is similar to their ancestors
environment - adaptation is not planned or
purposeful
What is selected?
The individual is selected.
Kinds of selection
Some of Bumpus’s survival data
Peppered Moth – Biston betularia – white and melanistic forms
on lichen covered and sooty trees
Distribution of Peppered Moths in Britain
Left map shows distribution in 1956, right map shows
distribution in 1996; Dark part of circle shows proportion of
dark form, light part of circle shows proportion of light form
Life stages of
Coho salmon –
top to bottom –
Eggs, fry, oceanic
Silverfish,
Hooknose male,
and female
Constraints to perfect adaptation
Coat Color Mutation in Florida Beach
Mouse – Peromyscus polionotus
Normal, dark mainland mouse on right; lighter
mutated island beach mouse on left; mutation due
to a change in a single nucleotide
Coat Color Mutation in Florida Beach
Mouse – Peromyscus polionotus
Gene Flow in Walleye
Walleye sampling sites
Walleye relatedness tree
Chimpanzee Hands And Feet
Drought Cycles in Iran
Phylogenetic Constraint – Egg Size
and Brood Patch in Penguins
Evidence of local adaptation
Environmental or Genetic
Variation in Yarrow?
Local adaptation in bentgrass Agrostis stolonifera
Trinidad Guppies - Poecilia reticulata
Male and Female
Two males
Adaptation and natural selection in
guppy populations
John Endler