Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors...
-
Upload
xiomara-tomkins -
Category
Documents
-
view
223 -
download
1
Transcript of Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors...
![Page 1: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/1.jpg)
Coevolution & Mutualism
1. Coevolution
2. Host-parasite systems
3. Coevolution among competitors
4. Character displacement
5. Mutualisms & symbioses
![Page 2: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/2.jpg)
• Coevolution – evolution of one species in response to characteristics of another
• Differs from other types of evolution in two ways:
![Page 3: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/3.jpg)
1. Coevolution involves mutual responses in the two species
– predator species evolves to be faster, allowing it to catch more
– results in greater selection on speed in the prey
– for “regular” evolution, there isn’t any response by the environment
![Page 4: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/4.jpg)
2. Coevolution promotes diversity of adaptations
– evolution often converges on the same solution for the same problems
– coevolution involves specific, unique responses to specific challenges
![Page 5: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/5.jpg)
The confusing definition of coevolution
Species A evolves an
adaptation in response to species B
Species B evolves in
response to the adaptation of
species A
![Page 6: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/6.jpg)
This isn’t coevolution
Species A has some trait
unrelated to species B
Species B evolves in
response to that trait in species A
![Page 7: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/7.jpg)
Not coevolution…
![Page 8: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/8.jpg)
Coevolution in host-parasite systems
• Hosts and parasites change evolutionarily in response to each other
• Resistance – the ability of the host to combat the parasite
• Virulence – the ability of the parasite to harm the host
![Page 9: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/9.jpg)
![Page 10: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/10.jpg)
Hosts evolved resistance to the parasitoids
![Page 11: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/11.jpg)
• Both resistance (in the host) and virulence (in the parasite) are costly– if the host is susceptible, selection favors
virulence– this causes selection for resistance in the
host…– leading to selection for less virulence in the
parasite (because virulence is costly)…– leading to selection for less resistance in
the host (because resistance is costly)…
![Page 12: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/12.jpg)
![Page 13: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/13.jpg)
Parasites that are too virulent may reduce their own fitness by killing their hosts.
![Page 14: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/14.jpg)
Coevolution & Mutualism (Chapter 20)
1. Host-parasite interactions
2. Coevolution among competitors
3. Character displacement
4. Mutualisms & symbioses
![Page 15: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/15.jpg)
Host-parasite interactions are due to genotype-genotype interactions– newly evolved pathogen strains may
overcome host resistance– host resistance may be specific to certain
genotypes
![Page 16: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/16.jpg)
![Page 17: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/17.jpg)
![Page 18: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/18.jpg)
Red Queen Hypothesis
• Parasites are constantly evolving into new forms to avoid host resistance
• Hosts are constantly under selective pressure to evolve new resistance genes
• Result is a “coevolutionary arms race” in which both parasite and host must constantly evolve just to stay in place…
![Page 19: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/19.jpg)
Plant-herbivore Coevolution
• Plants produce toxic “secondary” chemicals that reduce herbivory
• Some herbivores have evolved to detoxify the toxic chemicals.– herbivores may specialize on the hosts
whose defenses they have overcome– plants may evolve new defenses, and the
cycle continues (Red Queen)
![Page 20: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/20.jpg)
![Page 21: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/21.jpg)
![Page 22: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/22.jpg)
• Generic defenses against herbivory (spines, cellulose, etc.) and predation (speed, hiding, lack of smell, etc.) are not coevolution
• They don’t involve responses to an adaptation specific predator/herbivore
![Page 23: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/23.jpg)
Coevolution among competitors
![Page 24: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/24.jpg)
Character Displacement• According to the competitive exclusion law,
no two species can share the same niche
• When living in allopatry (spatially separated), two species may use the same resources (food, nest sites, etc.)
• Where these species live in sympatry (in the same geographic area), they will evolve to use different resources to avoid competition.
![Page 25: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/25.jpg)
Greater divergence in morphology in sympatry than in allopatry, is character displacement
![Page 26: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/26.jpg)
![Page 27: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/27.jpg)
![Page 28: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/28.jpg)
• Mutualism – mutually positive interaction between two species
• Commensalism – interaction in which one species benefits and the other is unaffected
• Symbiosis – association in which two species live together as one distinctive entity
![Page 29: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/29.jpg)
Mutualisms and commensalisms can be– obligate – neither can survive without the
other– facultative – nonessential
![Page 30: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/30.jpg)
Three Kinds of Mutualisms
1. Energetic & nutritional – transfer of energy/nutrients from one organism to another
2. Protective – defense against predators or herbivores
3. Transport – movement of seeds, pollen, or adult organisms
![Page 31: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/31.jpg)
Energetic Mutualisms
Gut symbiont– bacteria in animal guts digest plant
materials and produce vitamins/amino acids
– benefit to bacteria is a stable environment and a steady food source
![Page 32: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/32.jpg)
Mycorrhizal fungi – fungi that live intermingled with plant roots– fungi uptake nutrients from soil for plants– plants provide carbohydrates to the fungi– mycorrhizal fungi are found in almost every
plant– very important where nutrients are limited
![Page 33: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/33.jpg)
![Page 34: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/34.jpg)
![Page 35: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/35.jpg)
Honeyguides (energetic mutualism)
![Page 36: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/36.jpg)
![Page 37: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/37.jpg)
Protective Mutualisms
Ants/acacias – – acacias provide food, hollow stems for
nesting– ants attack herbivores and kill encroaching
plants– wrens nest in the acacias and are
protected from predators by the ants (commensalism)
![Page 38: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/38.jpg)
![Page 39: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/39.jpg)
Transport MutualismsPollination
– flowers trade nectar for pollen transport– can be general or species-specific
![Page 40: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/40.jpg)
Seed dispersal
Plants provide nutritious fruit, seeds to encourage dispersal by animals– many seeds require gut passage to
germinate– some plants trade-off consumption of some
seeds to ensure dispersal
![Page 41: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/41.jpg)
![Page 42: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/42.jpg)
Seed dispersal
Why does seed dispersal benefit plants? (why not just drop seeds?)
1. Avoid pathogens that the parent may harbor
2. Colonize new habitats where conditions may be better than near the parent
3. Find locations where germination is more likely (ant nests)
![Page 43: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/43.jpg)
• Facultative mutualisms– mixed-species flocks in birds– clownfish-anemone– associational defense with toxic plant
species
• Commensalism– birds’ nesting in tree cavities – epiphytes’ growing on trees
![Page 44: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/44.jpg)
Symbiosis – “living together”
• Lichen – alga and fungus
• Coral and zooxanthellae– coral capture food, nutrients– zooxanthellae photosynthesize and provide
sugars, energy– coral “signal” the algae to release sugars
![Page 45: Coevolution & Mutualism 1.Coevolution 2.Host-parasite systems 3.Coevolution among competitors 4.Character displacement 5.Mutualisms & symbioses.](https://reader030.fdocuments.net/reader030/viewer/2022032702/56649cc35503460f9498bb02/html5/thumbnails/45.jpg)