8: Evolution

Question 1

Charles Darwin

Answer 1

Theory of evolution

British

Question 2

Evolution is based on four basic principles of life

Answer 2

the differential success of certain variations of a heritable trait, because of competition for limited resources leads to the change over time of that trait in a population

Question 3

heritable

Answer 3

trait is part of the organism’s genetic code

a trait must be heritable in order for that trait to evolve

Question 4

variation

Answer 4

variation in traits in a population

random genetic mutations

Question 5

advantage/differential success

Answer 5

a trait must provide an advantage over other variations in order for evolution to occur

Question 6

competition

Answer 6

natural environments have limited resources and competition for these resources permits only some organisms to successfully reproduce before they die

Question 7

Is evolution a random process?

Answer 7

No! It is based on how well each trait improves an organism’s reproductive success

Question 8

T/F: Most random mutations are more likely to diminish than they are to improve an organism’s success

Answer 8

T

Question 9

Natural Selection

Answer 9

the competitive selection process by which detrimental traits are competitively discarded and advantageous traits are retained

Question 10

Organisms are grouped together based on their most recent…

Answer 10

shared common ancestors

Question 11

character

Answer 11

a heritable trait that can be described and labelled

Question 12

shared derived character

Answer 12

a character that is present in 2 or more groups and their common ancestor, but is not present in any more distantly related groups
ex. predentary of ornithischians

Question 13

Synapomorphy

Answer 13

aka: shared derived character

Question 14

Convergent evolution

Answer 14

the evolution of similar traits in 2 different lineages

Question 15

Parsimony/Occam’s razor

Answer 15

All there things being equal, the simplest answer is usually the right one

Question 16

A Clade

Answer 16

a group of species that share a common node
no size limits
must contain the ancestor of a group and all of its descendants

Question 17

phylogenic tree

Answer 17

family tress composed of nodes and branches

Question 18

node

Answer 18

where two branches diverge, and shows the point at which two lineages shared a common ancestor

Question 19

Linnean Hierarchy

Answer 19

Classifies organisms as belonging a Kingdom, Phylum, Class, Order, Family, Genus, Species

Question 20

Class Mammalia, Aves, and Amphibia are all…

Answer 20

subsets of the class Pisces (now called Osteichthyes)

Question 21

Thomas Henry Huxley

Answer 21

advocate for theory of evolution
First scientist to recognize that birds evolved from dinosaurs, cited Archaeopteryx as fossils of a “missing link” between dinosaurs and birds

Question 22

Archaeopteryx

Answer 22

“missing link” between dinosaurs and birds
Huxley
had teeth, clawed fingers, and long series of tail vertebrae like a dinosaur, and the long-wing and tail feathers of a bird

Question 23

Sinosauropteryx

Answer 23

the first non-avian (non-bird) dinosaur to be discovered with feathers

Question 24

Birds are classified as _______ dinosaurs

Answer 24

theropod

Question 25

the only clade of dinosaurs alive today

Answer 25

birds

Question 26

Bird definition 1: Archaeopteryx and all of its descendants

Answer 26

Problem: new phylogenic analyses sometimes show that Archaeopteryx is more closely related to the dromeosaurid theropods than to modern birds

Question 27

Bird definition 2: feathered dinosaur

Answer 27

Problem: as more and more feathered dinosaur fossils, like Yutyrannus, are found, more dinosaurs are included in this definition. ex. Tyranosaurs would now be considered birds

Question 28

Bird definition 3: Flying dinosaurs

Answer 28

Problem: it is difficult to determine which dinosaurs were capable of flying (as opposed to simply gliding

Question 29

Definition 4: Crown dinosaurs

Answer 29

This a technical term that means the last common ancestor for all extant birds and its descendants
Problem: this fails to recognize many feathered and flying dinosaurs that are more closely related to modern birds than to Archaeopteryx as birds
This definition is favoured by scientists
We use the term Avialae for the clade containing Archaeopteryx and all of its descendants