n San Francisco Bay, shorebirds compete for small invertebrates living in the mud. Due to natural selection, some birds have very long beaks and legs to reach deep areas and some have short curved beaks. The characters of these birds are so extreme that they are highly specialized in their food sources and there is little overlap in diet. The different body plans of these birds is an example of:   a specialized mutualism. resource partitioning. character displacement. competitive exclusion.

1. Examine the food webs for Lake Victoria, East Africa (fig 31.2 a,b) before and after the introduction of the Nile perch (Leveque 1995). Calculate the mean food chain length, percent of trophic groups at various levels, and connectance for each food web. Oreochromis Insectivorous Fish Chironomids Chaoborous Man Piscivorous Fish Zooplanktivorous Haplochromines Rastrineobola Zooplankton Detritus/Phytoplankton Lake Victoria in the 1970s Detritivorous Phytoplanktivorous Haplochromines Figure 31.2. (a) Food web structure of Lake Victoria before introduction of the Nile Perch. [continued on next page) Molluscivorous Fish Molluscs

Which of the following is the best evidence that a mutualism is NOT a byproduct mutualism? Group of answer choices A. Each partner changes the help they give based on the amount of help from the other B. Each partner benefits from the relationship C. Each partner is a member of a different species D. The observed partners are nonkin E. The observed partners are kin

The most intense interactions often occur between individuals of the same species. What concept discussed in this chapter can be used to explain this phenomenon?