Lecture 19 - Scale & Multiple Proxies

Question 1

what are the conflicting models of evolution

Answer 1

Savanna Hypothesis: main argument for bipedalism in hominins, simplistic and doesn’t fit evidence well - (especially sites where Ar. ramidus etc lived that were wooded)

Turnover Pulse Hypothesis: climate changes cause species ranges to become fragmented, and extinction/appearing of species comes in pulses

Multiple Pulses

Variability Selection; focuses on increases in variability in climate that led to adaptations for ecological flexibility, favors evolution of different sorts of traits rather than a constant that favors one type of environment/ecological sources over others

Question 2

spatial versus temporal scales examples

Answer 2

mammal tooth evidence - forms within a year, only a few years of evidence but not spatially restricted

soil evidence - forms over thousands of years, averages a lot of time for isotopic evidence, but spatially restricted

Question 3

global scale proxy data types

Answer 3

• oxygen isotope record, oceanic core records
• only tells average conditions around globe, not region

Question 4

hypotheses consistent with global scale proxy data

Answer 4

Turnover Pulse, Savanna Hypothesis → from global records, we can see dramatic shifts that have been aligned with evolutionary events in regional areas

Question 5

why is it hard to link human evolutionary events with global scale data

Answer 5

• cannot say that global data is the sole contributor to regional evolutionary changes
• but, should not ignore because indicates long-term change

Question 6

mosaic habitats

Answer 6

many localized samples from same site at different places show different data - habitat heterogeneity

Question 7

red queen hypothesis

Answer 7

= biotic interactions influences evolution the most

• if prey species that is interacting with predator species, back and forth of developing adaptations to survive

Question 8

court jester hypothesis

Answer 8

= external environment forces evolutionary events

• broad/global environmental changes that drive major evolutionary events
• Turnover Pulse Hypothesis

Question 9

red queen vs court jester

Answer 9

not mutually exclusive, maybe two ends of a spectrum, also a question of spatial/temporal scale

Question 10

shifting heterogeneity model

Answer 10

emphasizes role of orbital cycles and volcanism in shaping habitat heterogeneity