Lecture 14: Concepts of Evolution

Question 1

What is evolution?

Answer 1

process of biological change by which species of different organisms change over time

also defined study of the history of life forms on Earth

Question 2

Types of evolution

Answer 2

microevolution, macroevolution

Question 3

microevolution

Answer 3

process by which organisms change
in small ways over time

gradual short-term adaptation of species to environment

Question 4

macroevolution

Answer 4

refers to larger evolutionary changes that
result in new species

long-term evolution across taxonomic groups including evolution of one or more NEW taxa

Question 5

How to study microevolution

Answer 5

Sometimes possible to quantify & study through direct observation of living populations (e.g., Darwin’s finches)

Question 6

Why organisms evolve?

Answer 6

evolutionary arms race; camouflage; for better fitness

Question 7

Unity of Life

Answer 7

Life arises only from pre-existing life (spontaneous
generation is disproved)

All living organisms are composed of one or more
cells

All organisms share a single DNA code (A, T, G, C)

Question 8

Diversity of Life

Answer 8

Earth has been host (now and in the past) to a
staggering variety of life forms

Question 9

How can life be so diverse yet still unified?

Answer 9

life changes over time

Question 10

Lamarckism

Answer 10

Jean Lamarck, 1809

First hypothesis of evolution (now rejected)

Question 11

What is Lamarckism about?

Answer 11

Individual organisms can acquire new traits during
their own lifetimes …they can change their own
bodies through effort, behavior, use (or disuse) of
parts, etc.

Their offspring will inherit these acquired traits.

Question 12

Why is Lamarckism wrong?

Answer 12

Even if an organism does change its body
during its lifetime, its offspring will not inherit those
changes. Organisms cannot alter their genes or DNA
through their behavior!

Doesn’t take into consideration mutations, genetic variation

Question 13

4 postulates of Lamarckism

Answer 13

1. New needs (Giraffe neck)
2. Use and disuse of organs (limbless snakes)
3. Inheritance of acquired characters
   (Development of flightless birds like ostrich from
   flying ancestors)
4. Speciation (new characters accumulate
   generation after generation and become new
   species)

Question 14

Darwin’s Theory of Evolution

Answer 14

proposed that Galapagos finches shared a common ancestry, but had evolve to become adapted for particular habitat on each island

Question 15

Darwin’s observations of the finches

Answer 15

no two members of the same species are perfectly identical. Each organism is born slightly different from its parents, from its brothers and sisters, and from other members of that species

Question 16

explanation of Darwin’s observations of the finches

Answer 16

random reshuffling of genes during sexual reproduction, plus the occasional mutation

reasoned that over many generations,
a lot of little differences can add up to
some really enormous changes!

Question 17

natural selection

Answer 17

more offspring will be produced than will survive (environment has a fixed & finite “carrying capacity”)

Offspring will compete with one another for survival and limited resources

Random variety of traits will appear among those offspring

Some traits are more favorable (or “adaptive”) than others for competing and surviving in a particular environment (“Survival of the Fittest”)

Those offspring which happen to be born with more adaptive traits will have a better chance of surviving long enough to reproduce, thereby passing on their adaptive traits

In the next generation there will be a higher frequency of adaptive traits (= Evolution)

Question 18

Key of evolution

Answer 18

The passing of selected
TRAITS that enhances the organisms’
ability to survive and/or reproduce from
one generation to the next

Question 19

What evidence did Darwin use?

Answer 19

Fossil records,
comparative anatomy, and embryology

Question 20

What did Darwin not have?

Answer 20

The ability to study DNA sequencing and genes (a fundamental component of the modern Theory of Evolution!)

Question 21

Evolutionary biology

Answer 21

the scientific study of the evolutionary processes that produced the diversity of life on Earth