1. Coevolution:
The joint evolution of two species with close
ecological relationships
-- evolution of each is partly dependent on the other
-- includes parasite-hosts, mutualisms

2. vertebrates (social parasitism)
Parasites include:
viruses
bacteria
fungi
invertebrates
vertebrates (social parasitism)
Many are highly specialized to only one host species
e.g, bird lice, botflies
Plant mite
Human head lice

3. Host defenses against parasites
--Biochemical (e.g., antibodies)
--tissue growth to contain parasite
(e.g., galls)

4. To eradicate parasites
-- gene-for-gene response
-- multiple defenses at once (not really
possible)
-- turn it into a mutualism

5. Mutualisms: coevolved systems where two species
interact to the benefit of both
-- e.g., Rhizobium, Mycorrhiza
-- symbiotic and nonsymbiotic
-- obligate and facultative
Landmark paper on coevolution and mutualism
in ecology:
Erhlich, Paul and Peter Raven Butterflies and
plants: a study in coevolution. Evolution 18:

6. Social parasitism in birds cuckoos
cowbirds
some ducks
2 Brown-headed Cowbird eggs in a Blue-winged Warbler's nest
warbler nest with two
cowbird eggs
Brown-headed cowbird

7. parasitism to mutualism
Oropendolas and
Cowbirds
parasitism to mutualism

9. -- symbiotic and nonsymbiotic
Landmark paper on coevolution and mutualism
in ecology:
Erhlich, Paul and Peter Raven Butterflies and
plants: a study in coevolution. Evolution 18:
-- symbiotic and nonsymbiotic
-- obligate and facultative

10. Pine cone seeds and crossbills

11. Ants and acacia trees

12. Dodo
Mauritius Island
Calvaria trees
Nonsymbiotic obligate mutualism (for tree)

13. Honey badger and honeyguide: a nonsymbiotic
facultative mutualism

14. Mutualisms are not always ideal
-- not always a ‘happy’ relationship
-- e.g., yucca moths pollinate plants,
larvae feed on seeds
-- too many larvae, flower dies and both
species lose out
-- puts constraints on fecundity

15. Now know that mutualisms and other co-evolved
systems are common in nature
-- functional links above ground to below ground
-- nutrient cycling and ecosystem function often
dependent on these relationships
-- more discovered all the time
Tree shrew and pitcher
plant in Borneo
Wax from plant, nitrogen
in feces from shrew
Pitcher plants and tree shrews have formed a relationship of mutual benefit: the shrews feed on the plant’s wax and defecate into its convenient “lavatory”, so providing the plant with 60 to 100 per cent of its nitrogen needs.

16. Pollination Ecology

17. Hummingbirds: generalists and specialists

19. Mutualisms: last word
--not always a ‘happy’ relationship
--e.g., yucca moths on yucca plants
--constraints on fecundity