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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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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 • Most predators are also prey, thereby always trying to avoid detection, when they also become detected • There is both cryptic and warning coloration
Coevolution • Parasites and hosts have a complex relationship • Most parasites tend towards host specification while hosts increase their tolerance for specific parasites
Coevolution • 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
Coevolution • 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
Coevolution • What are the ecological relationship 2 organisms may have? • Mut Com N A P/P Comp • +/+ +/0 0/0 0/- +/- -/-
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
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 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 pollination • Bat pollinated flowers tend to white and musky smelling
Coevolution pollination • Hummingbird flowers tend to have rather long tubes and are colored red, orange, purple, or yellow
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
Coevolution pollination • The story of a beetle, a flower, a loney night, and freedom…at a cost
Coevolution pollination Parasite!!
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
Coevolution pollination • Many of these plants have flowers that are cauliflorous • Typically hang low and on long branches
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?
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 plants • ‘Protectionist’ hypothesis • ‘Exploitationist’ hypothesis • How would you determine the difference?
Coevolution ants and plants • Cecropia nectaries are termed ‘Mullerian bodies’ and are located at the base of the leaf petiole
Coevolution ants and plants • In addition, the underside of leaves has velvet like hairs (cecropia plants without ants lack these)
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 plants • What is the moral character of an ant?
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
Coevolution the importance of fruit • There are also many bird families dedicated to a frugivorous lifestyle
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)
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?
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 Cheaters!!
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?
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 plants • Consider the purple-throated fruit crow • It lives with 3-4 individuals and shows little/no aggression • Group feed a single nestling
Coevolution ants and plants • Mammals who are largely frugivorous also tend towards sociality (e.g. pacas, coatimundies and pecarries)
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
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
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’
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?
