Ch 5- Macroevolution

Question 1

Homologies

Answer 1

Structures that are shared through descent from a common ancestor
- Ex. Vestigial traits

Question 2

Analogies

Answer 2

Structures in organisms that are used for the same function, but have developed independently and are not the result of common descent

Question 3

Homoplasy

Answer 3

The process by which similarities can develop in different groups of organisms

Question 4

Biological Systematics-

Answer 4

• Science of classification and taxonomy
• Rules and guidelines for categorizing biological diversity and deriving phylogenies
• International Commission on Zoological Nomenclature (ICZN)

Question 5

Two Major Approaches

Answer 5

1. Evolutionary Systematics
   - More traditional approach
2. Cladistics
   - More recent and common approach
   - Used by biological anthropologists today

Question 6

Cladistics

Answer 6

• Explicitly and rigorously defines the kinds of homologies

- Focus on derived traits not primitive/ancestral traits

Question 7

Ancestral vs. Derived Traits

Answer 7

• Ancestral
  • Deep evolutionary history, shared traits
• Derived
  • Recently evolved traits, not-shared, newer

Question 8

Cladogram

Answer 8

Diagram that groups based on phylogenetic history

• Does not indicate time
• Does not specify ancestor-descendant relationships

Question 9

Definition of a Species

Answer 9

Mayr 1942

• “Species are groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups”
• Both geographic and a variety of pre- and post- mating mechanisms prevent mating or development of fertile offspring

Question 10

The Fossil Record:

How can we differentiate between species?

Answer 10

We cannot view breeding and mating patterns of extinct animals
Therefore we must use variation
• Traditionally could only assess variation in fossilized elements
Ex. a handful of teeth, now we use genetics
• But how much variation is enough?
◦ Look to modern species to get an idea

Question 11

Variation

Answer 11

• Variation due to age, sex, and geography = intraspecific variation
• Variation due to reproductive isolation = interspecific variation
* We are more interested in interspecific

Question 12

The Fossil Record:

Time, space and morphology

Answer 12

Time- millions of years apart
Space- geographic locations, living on the ground vs. in the trees
Morphology- physical characteristics and genetics

Question 13

Splitters vs. Lumpers

Answer 13

Splitter
- Speciation was frequent
- Inclination to split variation into many groups
Lumpers
- Speciation was less frequent; most variation is intraspecific
- Inclination to split variation into few groups

Question 14

Fossils:

Formation, age, components

Answer 14

Form by:
• Mineralization
• Tree serum
• Imprints- footprints, leaf imprints
Oldest microorganisms from 3 billion years ago
Shells, bones and teeth – “bone to stone”
- Already composed of some mineral

Question 15

Mammalian Evolution:

How many living species?

Answer 15

About 5,400 living species

Question 16

Adaptive Radiation:

Larger Brains

Answer 16

• Cerebellum enlarged, more convolutions
• Better processing of sensory information
• Bigger brain required a longer period of growth
• Placental mammals have the longest period of in utero development

Question 17

Adaptive Radiation:

Differently Shaped Teeth

Answer 17

• Ancestral mammalian pattern is 3 incisors, 1 canine, 4 premolars, & 3 molars in each quarter of the mouth (=44 teeth)
• Can process a wider array of foods

Question 18

Adaptive Radiation:

Warm-Blooded

Answer 18

Endothermic

- Maintenance of a constant internal body temperature

Question 19

Adaptive Radiation:

Definition

Answer 19

• Rapid expansion and diversification of life-forms into new ecological niches

Question 20

Anagenesis:

Phyletic Evolution

Answer 20

• Small changes over long periods
• Enough time will change one species into another
• Depends on environmental change and environmental pressure
• No ‘rule’ or law exists stating how much microevolutionary change must occur to result in new species

Question 21

Cladogenesis:

“Branching Evolution”

Answer 21

• An evolutionary splitting event where a parent species splits into two distinct species
• Clade = cluster of species derived from a single common ancestor
• Over time will increase species richness