Day 18 November 6th The Tree of Life

Dr. Amy B HollingsworthThe University of Akron

Fall 2014

Are humans more advanced, evolutionarily, than cockroaches?

Can bacteria be considered “lower” organisms?

Monophyletic Groups

A group in which all of the individuals are more closely related to each other than to any individuals outside of that group

Determined by looking at the nodes of the trees

Constructing evolutionary trees requires comparing similarities and differences between organisms.

10.9 Similar structures don’t always reveal common ancestry.

The mapping of species’ characteristics onto phylogenetic trees

Physical features – pre-1980 just looking at characteristics

DNA sequences – post 1980, made it easier to track organisms and similarities

Convergent Evolution - which occurs when populations of organisms live in similar environments and so experience similar selective forces.

• Analogous traits - are characteristics (such as bat wings and insect wings) that are the same because they were produced by convergent evolution and not because they descended from a common structure in an ancestor they shared.

Analogous traits:Features that are produced by convergent evolution

Homologous traits:Features that are inherited from a common ancestor

How do you know whether traits are homologous or analogous?

DNA Analysis

10.10–10.13

Macroevolution

gives rise to great

diversity.

10.10 Macroevolution is evolution above the species level.

Short-term and Long-term Results

Microevolution

Macroevolution

10.11 The pace of evolution is not constant.

10.12 Adaptive radiations are times of extreme diversification.

When a small number of species diversifies into a much larger

number of species

Three Phenomena May Trigger

Adaptive Radiations

All result in access to plentiful new resources.

Colonizers find a large number of opportunities for adaptation and diversification.

Galapagos finches Hawaiian fruit flies

Innovations such as the wings and rigid skeleton that appeared in insects…

…helped them to diversify into the most successful group of animals.

There are more than 800,000 species today!

10.13 There have been several mass extinctions on earth.

Background Extinction

Extinctions that occur at lower rates during periods other than periods of mass extinctions

Occur mostly as the result of natural selection

Background and Mass Extinctions Have Different Causes

Mass extinctions are due to extraordinary and sudden changes to the environment.

Background extinctions occur mostly as the result of natural selection.

10.14−10.17An overview of the diversity of life on earth: organisms are divided into three domains.

10.14 All living organisms are divided into one of three groups.

Classification Systems

The two-kingdom system• Animal and plant

The five-kingdom system • Monera, plant, animal, fungi, and protists

Classification Takes a Leap Forward

Carl Woese, an American biologist, and his colleagues

Examined nucleotide sequences

Tracking changes

Woese’s approach is not perfect.

Are viruses alive?

10.15 The bacteria domain has tremendous biological diversity.

Why is morning breath so stinky?

Bacteria Are a Monophyletic Group

All bacteria have a few features in common:

Single-celled organisms with no nucleus or organelles

One or more circular molecules of DNA Several methods of exchanging genetic information Asexual organisms

10.16 The archaea domain includes many species living in extreme environments.

The archaea exhibit tremendous diversity and are often divided into five groups based on their physiological features.

Thermophiles – live in hot places

Halophiles – live in salty places

High- and low-pH tolerant

High-pressure tolerant – found 2.5 miles under the ocean’s surface

Methanogens

10.17 The eukarya domain consists of four kingdoms.

Plants, Animals, Fungi, and Protists