This document discusses proximate and ultimate causation in evolution. It provides an example of Geoff Hill's work on house finch coloration. Proximately, differences in female plumage coloration across populations are caused by differences in local carotenoid-rich food sources. Differences between males and females are caused by males actively foraging for these foods while females do not. Ultimately, male plumage brightness evolved through sexual selection as brighter males attracted more mates, had better disease resistance, provided more parental care, and produced healthier offspring.

1. PROXIMATE
AND
ULTIMATE CAUSE
BY
MUHAMMAD IRFAN
M.PHIL ZOOLOGY
UNIVERSITY OF THE PUNJAB, LAHORE

2. PROXIMATE
PERSPECTIVE
 It deals with immediate causation
(Mechanism+Development)
 How it is? What is it?
Method of Analysis (Example: Male Aggression)
 Must know natural selection pressure that acted on male
aggression > aids in analysis
 Keen observing: Suspect > Male use aggression to gain
access to food by studying foraging behavior
 Some hormones are involved in male aggression
 It helps us to understand the raw material that natural
selection may operate on in the future
 Conclusion
It sheds light on the variation available for natural selection
to act on in the future

3. ULTIMATE
PERSPECTIVE
It delas with forces that
have shaped a trait over
evolutionary time?
Why it is that?
How evolutionary forces
operate > past, present,
future?

4. Geoff Hill’s
Work
House Finch Coloration
Proximate: Causes of different
coloration? What?
Ultimate: Persistence over evolutionary
time? Why?
To answer, studied > Foraging behavior,
mate choice and parental care

5. Study
of
Proximate
Causation
 Study intra and inter population comparison
 Controlled feeding comparison
 Prior Knowledge: carotenoid pigments (red)
 Males synthesize their own, females not
 Difference of Plumage in Males
Hill’s prior work > male plumage brightness. Differences in
intra and inter population were correlated with the diet
during the development phase
 Difference of Plumage in Females
To understand, done experiment.
2 groups
Treated one with food and other with food + Canthaxanthin
One group drab plumage, other with brighter plumage

6. ANSWERS
 What causes differences between
population differences in female coloration?
 What causes differences in plumage
coloration between males and females?
INTER-POPULATION DIFFERENCES
 Did comparison with Michigan’s population
 Differences occurred due to carotenoid-
based food sources in those localities
 More such food > More the bright colour
 It explains the difference in plumage
coloration among females across
populations

7. Difference
Between
Male VS Female
It depends upon the foraging
ways
Not on the availability of
carotenoid-based foods
available in the same locality
Males actively search for
carotenoid-based foods, while
females not.

8. STUDY
OF
ULTIMATE
CAUSATION
 Question 1: Why do males, but not
females, actively search for carotenoid-
based foods?
 Answer: Hill hypothesized that males
receive significant benefits. What are these
benefits?
 Experiment: Hair dyes were used to
brighten/lighten male colour
 Those males attracted more mates i.e. the
reason to search actively more carotenoid-
rich food

9. STUDY
OF
ULTIMATE
CAUSATION
 Question 2: Why females prefer males
with brighter colour? The ultimate
question regarding the mate choice.
 Answer: 3 reasons to do it.
 A) Better fight-off with pathogens (He
inoculated Mycoplasma gallicepticum)
 B) Better parental care (Brighter male fed
twice their babies than the drabber males)
 C) Better foragers, hence more fitness,
healthy offsprings