Ch 5- Macroevolution Flashcards Preview

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Flashcards in Ch 5- Macroevolution Deck (21)
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1

Homologies

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

2

Analogies

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

3

Homoplasy

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

4

Biological Systematics-

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

5

Two Major Approaches

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

6

Cladistics

- Explicitly and rigorously defines the kinds of homologies
- Focus on derived traits not primitive/ancestral traits

7

Ancestral vs. Derived Traits

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

8

Cladogram

Diagram that groups based on phylogenetic history

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

9

Definition of a Species

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

10

The Fossil Record:
How can we differentiate between species?

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

11

Variation

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

12

The Fossil Record:
Time, space and morphology

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

13

Splitters vs. Lumpers

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

14

Fossils:
Formation, age, components

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

15

Mammalian Evolution:
How many living species?

About 5,400 living species

16

Adaptive Radiation:
Larger Brains

- 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

17

Adaptive Radiation:
Differently Shaped Teeth

- 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

18

Adaptive Radiation:
Warm-Blooded

Endothermic
- Maintenance of a constant internal body temperature

19

Adaptive Radiation:
Definition

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

20

Anagenesis:
Phyletic Evolution

- 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

21

Cladogenesis:
"Branching Evolution"

- 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