Coral snakes and kingsnakes have a true batesian

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• coral snakes and kingsnakes have a true Batesian relationship. • the poison dart frogs a,b,c are all one species in different parts of range shared by three different species d,e,f; all are toxic. herbivore avoidance • Plants may not be able to run, but they can protect themselves: • spines and thorns, thick bark offer some physical protection. • chemical defences are also common, including numerous poisons, insecticides, and distasteful compounds. • many herbs and spices are flavourful because of plant defence compounds. • fruits are different: many fruits are sweet and delicious because they want to be eaten red hot chilies and cool chicks • the capsaicin that makes a pepper hot is a chemical protectant: • the number one cause of seed death is a fungus called Fusarium. • Fusarium enters the fruit through wounds caused by insect herbivores. • capsaicin kills microbes and deters insects as well as mammals. • birds don’t have receptors for capsaicin and eat the ripe chili fruit, dispersing the seeds. chilies not cheap • But capsaicin is complex and expensive to produce . • A tradeoff between seed quality and protection is apparent: • pepper plants are polymorphic for pungency . • where the insect wounding / fungus is uncommon, peppers tend to be mild. • mild peppers are larger and have thicker, sturdier seeds.
symbioses • close interactions between species over their life histories are called symbioses. • symbioses can always benefit one species, but have different outcomes on the second: • parasites have a deleterious impact upon their host. • mutualists exist in relationships that are beneficial to both species. • commensalism involves a benefit to one species with no impact upon the other. don’t shoot the messenger vector? • Marrelli et al. made transgenic Anopheles mosquitoes that impair transmission of Plasmodium in the midgut. • Ran multi-generation cage selection experiments: • transgenics outcompeted wildtype mosquitoes, becoming more frequent . • releasing malaria-resistant mosquitoes could be a viable strategy for combating the disease. Mutualism • +/+ symbioses are hard to find and to verify • once the relationship is obligate, it is hard to argue that one or both partners mightn’t be better off without the other. • is the mt in a mutualistic relationship? or enslaved? • the zooxanthellae that corals use? • ants have a more than a few putative mutualisms: • with aphids • with fungi • with plants Of Ants & Acacia Trees • Acacia ants defend acacia trees whilst the acacia provides sweep sap that the ants can feed on. • the ants drive away and attack herbivorous insects, chew off saprophytes (plants that grow on other plants), and even trim other plants around the acacia. • considered a facultative mutualism because each species can live on its own but benefits from association.

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