AIM: SWBAT cite significant evidence for

evolution

Please Do Now: 1) Define ecological niche2) Brainstorm some unique features of the

“urban ecosystem” (ex: lots of tall buildings)

Agenda Do Now Data Analysis Intro What is Evolution? Polar Bear Adaptation Video

Data Analysis You will be a presented a series of

graphs and charts (every Thursday) For each chart or graph, on a blank

sheet of paper you will answer 1-2 questions.

Once we have gone through all of them, you will be posed a question that unifies all the figures. Respond in 3-4 sentences.

Polar Bears 1) What is the

long term trend in the size of the polar bear populations?

Polar Bears1) What month were

these scientists measuring sea ice in? Over what time period?

2) What is the overall trend in sea ice coverage?

Polar Bears 1) How does a

decline in the number of seals affect the number of polar bears?

Polar Bears 1) Is the polar bear

decline uniform throughout its range?

2) Where are polar bears better studied? Russia or the U. S. and Canada?

Polar Bears Based on the graphs you have seen,

what do you think the fate of polar bears will be in the future? Why do you think this is? (Cite specific examples from the graphs).

What is evolution? CHANGE OVER TIME in the

characteristics of a POPULATION (a group of organisms of the same species)

Does not happen on the individual level!

Usually occurs very slowly over hundreds and thousands of years.

Wait, how do I use the word population in ecology?

YES: To refer to a group of organisms in the same area or sharing the same traits. (There is a population of Black Squirrels in McCarren Park).

NO: As a number (The population of Squirrels in McCarren Park is 200)

How do we know evolution has taken place over time?

Homologous structures Common Ancestry Adaptation Many more reasons

Common Ancestry Common Ancestry is the idea that all

life evolved from an original single celled organism about 4 Billion Years Ago

Ever since then, single species have been diverging to form 2 separate species from 1, because of natural selection.

Tree of Life

Homologous Structures Are features in different species that

show evidence for evolution from a common ancestor because they have similar shapes and compositions.

Example: the limbs of very unrelated animals all have the same bones.

Adaptation by Natural Selection An adaptation is a trait

(characteristic) that has a functional role in the life of an organism

Developed and maintained in a population by natural selection

Without it, the organism would not be as well suited to its niche

During the video As an exit ticket, please identify 3

adaptations the polar bear has to its environment, and explain how they are adaptive.

(You can do it on the bottom of your data analysis page).