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Coevolution . Herbivores eat plants Plants are noxious or toxic Herbivores help recycle nutrients that plants subsequently utilize, pollinate, and disperse seeds This is a complex relationship. Coevolution .

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  • Herbivores eat plants
  • Plants are noxious or toxic
  • Herbivores help recycle nutrients that plants subsequently utilize, pollinate, and disperse seeds
  • This is a complex relationship
  • Most predators are also prey, thereby always trying to avoid detection, when they also become detected
  • There is both cryptic and warning coloration
  • Parasites and hosts have a complex relationship
  • Most parasites tend towards host specification while hosts increase their tolerance for specific parasites
  • These are all examples of the evolutionary arms race (e.g. the escalation of adaptation and specialization) or coevolution
  • However, not all relationships, even when appearing intimate, are coevolutionary
  • Only when species evolve clearly in relation to mutual selection pressures is the relationship properly defined as coevolutionary
  • For example, sloths commonly harbor tiny moths that reside within the recesses of their fur
  • The lay eggs in the sloth’s dropping
  • What are the ecological relationship 2 organisms may have?
  • Mut Com N A P/P Comp
  • +/+ +/0 0/0 0/- +/- -/-
coevolution pollination
Coevolution pollination
  • Many tropical plants are completely dependent upon insects, birds, or bats for survival
  • While they may ingest some of the pollen between visitation events, enough gets to another individual
  • Thus, both parties benefit
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Coevolution pollination
  • “the tubes of the corollas of the common red and incarnate clovers do not on a hasty lance appear to differ in length; yet the hive-bee can easily suck the nectar out of the incarnate clover but not out of the common red clover, which is viisted by humble-bees alone”
  • Darwin
coevolution pollination9
Coevolution pollination
  • As mentioned previously, animal (and insects) pollination is very common in the tropics
  • Only grasses, sedges, pines, and other savanna species are the only tropical plant groups dominated by wind pollination
coevolution pollination10
Coevolution pollination
  • Bat pollinated flowers tend to white and musky smelling
coevolution pollination11
Coevolution pollination
  • Hummingbird flowers tend to have rather long tubes and are colored red, orange, purple, or yellow
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Coevolution pollination
  • The best pollinators are those that fly relatively long distances, such as the Euglossine bees. Why?

To ensure cross-pollination

between widely separated plants

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Coevolution pollination
  • The story of a beetle, a flower, a loney night, and freedom…at a cost
coevolution pollination16
Coevolution pollination
  • Over 500 plant species wholly or partly depend upon bats as pollinators (termed chiropterophilous)
  • While many flowers are vase shaped, others are brush like
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Coevolution pollination
  • Many of these plants have flowers that are cauliflorous
  • Typically hang low and on long branches
coevolution ants and plants
Coevolution ants and plants
  • Ants are everywhere in the tropics
  • Ants can easily outweigh the vertebrate biomass in a tropical forest
  • Unlike in temperate zones, diversity and abundance is greatest inside the forest
  • Why isn’t this true in temperate zones?
  • What about an altitudinal gradient?
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Coevolution ants and plants
  • Some plants species posses nectar-secreting glands (extra floral glands) as well as other structures (e.g. domatia) that collectively act to attract ants
  • A broad range of plants (19 families) have been classified as ‘ant-plants’ or myrmeophytes
  • Found in tropics throughout the world
coevolution ants and plants20
Coevolution ants and plants
  • ‘Protectionist’ hypothesis
  • ‘Exploitationist’ hypothesis
  • How would you determine the difference?
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Coevolution ants and plants
  • Cecropia nectaries are termed ‘Mullerian bodies’ and are located at the base of the leaf petiole
coevolution ants and plants22
Coevolution ants and plants
  • In addition, the underside of leaves has velvet like hairs (cecropia plants without ants lack these)
coevolution ants and plants23
Coevolution ants and plants
  • Janzen determined that for one species of Acacia (bull’s horn), ants patrol and attach insects and other plants attempting to utilize their host
coevolution ants and plants24
Coevolution ants and plants
  • What is the moral character of an ant?
coevolution the importance of fruit
Coevolution the importance of fruit
  • Fruit is relatively abundant and relatively constant
  • Anytime this occurs with a resource, something will specialize on it
  • There are no temperate frugivores (>50% of diet)
  • In the tropics many mammals (e.g. monekys, bats, agoutis) are frugivores
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Coevolution the importance of fruit
  • There are also many bird families dedicated to a frugivorous lifestyle
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Coevolution the importance of fruit
  • Is there a downside to a frugivore diet?
  • Yeah…protein
  • May result in much searching (large spatio-temporal variation in fruiting)
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Coevolution the importance of fruit
  • Is there a downside to a frugivore diet?
  • Yeah…protein
  • May result in much searching (large spatio-temporal variation in fruiting)
  • How would describe this relationship?
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Coevolution the importance of fruit
  • A mutualistic relationship in which some reward is given for the opportunity to disperse
  • However, anytime there is something of value, there will be
  • Of course, not all plants invest in fruits
  • Wind dispersal is common (31%) in the canopy
  • But down in the forest, they need help


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Coevolution the importance of fruit
  • Consider the evolutionary relationship between birds and fruit
  • Fruit is going to spatially and temporally patchy, but could be locally abundant
  • A particular tree can be full of fruit for a short period, but must be barren most of the year
  • What type of behavior does this promote?
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Coevolution the importance of fruit
  • The sociality of fruit-eaters
  • Why? Finding it is the hard part
  • Once found, enough for everyone
coevolution ants and plants33
Coevolution ants and plants
  • Consider the purple-throated fruit crow
  • It lives with 3-4 individuals and shows little/no aggression
  • Group feed a single nestling
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Coevolution ants and plants
  • Mammals who are largely frugivorous also tend towards sociality (e.g. pacas, coatimundies and pecarries)
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Coevolution the importance of fruit
  • Frugivores have a lot of free time…so what to do?
  • Male bearded bellbird spends 87% calling to females
  • Male white-bearded manakin spends 90% courting females
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Coevolution the importance of fruit
  • Because of the potential abundance of fruit, they can be quite numerous relative to others
  • E.g. in Trinidad, 717 ind of 2 sp of manakins were netted while 11sp of tyrannids were netted, but their total was not approaching that of the manakins
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Coevolution the importance of fruit
  • Trees are trying to attract seed dispersers
  • Not all disperers are good
  • Many drop the seeds almost immediately, leaving them within the ‘parent shadow’
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Coevolution the importance of fruit
  • Do you want to put out a fruit good for many or specialize?
  • Should you be big or small?
  • What are the relative benefits of being big? Small?