Las Alas Def Diahle-Nor:152016 In-Class Handout Results from Tewksbury and Nabha
ID: 182063 • Letter: L
Question
Las Alas Def Diahle-Nor:152016 In-Class Handout Results from Tewksbury and Nabhan's Experiments 60 20 75 50 25 0 0 Cactus Mouse (5) Packrat (S) Thrasher (10) Figure 1. The average percentage of fruits consumed by animals in the laboratory. The following ingestion of fruits by thrashers, numbers beside each species are the number of packrats and cactus mice. The numbers in animals tested. The zeros indicate cases where brackets are the number of animals for each no fruits were consumed. The bars represent ± | treatment. Figure redrawn from Tewksbury 1 standard error. Figure redrawn from Tewksbury and Nabhan (2001). Figure 2. The percentage of seeds germinating and Nabhan (2001). Statistical tests were performed to determine if There was no difference in seed germination the observed differences in consumption of between the seeds that were not ingested by hackberries, mild chilies and hot chilies wereanimals and seeds consumed by thrashers due to chance variation in the amounts of eachP-0.593). There was a significant difference type of fruit consumed or to actual difference in in germination between the seeds that were fruit consumption. When results of statistical not ingested by animals and the seeds tests are reported, the "P stands for probability. A probability is a measure of the (P0.0005) chance of something occurring. consumed by packrats and cactus mice Cactus mice and packrats ate more hackberries than chilies and the differences were statistically significant (P=0.008 for cactus mice, Ps0.0005 for packrats). The cactus mice and packrat had not first tasted the hot chilies. There was no statistically significant difference in the amount of each fruit consumed by the thrashers (P-0.219). s ate the mild chilies only if theyExplanation / Answer
From the above experiment rodents avoided the hot chillies entirely. The thrashers ate all three offerings with equal gusto. Previous studies have shown that birds are unable to sense capsaicin.
The rodents did not eat chillies because of the presence of capsaicin. These findings explain why chilli plants make capsaicin, the compound that gives them their heat. It deters animals whose guts destroy chilli seeds, leaving more for creatures that disperse the seeds in favourable locations.
The chilli’s strategy represents a remarkable departure in plant evolution, Whereas most plants in the nightshade family (which includes chillies, as well as important food crops like potatoes and tomatoes) produce alkaloid compounds that deter a wide range of predators, chillies are only plants known to have a directed deterrence strategy.
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