FIGURE 19–12 Convergent Evolution Mammals that feed on ants and termites evolved independently five times. Although each species is unique, each has evolved powerful front claws, a long hairless snout, and a tongue covered with sticky saliva. These adaptations are useful for hunting and eating insects.
d▸ Modern Adaptive Radiations Galápagos finches and Hawaiian honeycreepers are two examples of adaptive radiations in modern organisms. In each of these cases, numerous species evolved from a single founding species. Both finches and honeycreepers evolved different beaks and behaviors that enable each of them to eat different kinds of food.
Convergent Evolution Sometimes, groups of organisms evolve in different places or at different times, but in similar environments. These organisms start out with different structures on which natural selection can operate. But they face similar selection pressures. In these situations, natural selection may mold different body structures in ways that perform similar functions. Because they perform similar functions, these body structures may look similar. Evolution produces similar structures and characteristics in distantly related organisms through the process of convergent evolution. Convergent evolution has occurred often in both plants and animals. For example, mammals that feed on ants and termites evolved not once, but five times, in different regions as shown in Figure 19–12. Remember how Darwin noted striking similarities among large, distantly related grassland birds? Emus, rheas, and ostriches are another example of convergent evolution.
Coevolution
What evolutionary characteristics are typical of coevolving species?
Sometimes the life histories of two or more species are so closely connected that they evolve together. Many flowering plants, for example, can reproduce only if their flowers attract a specific pollinator species. Pollinators, in turn, may depend on the flowers of certain plants for food in the form of pollen or nectar. The process by which two species evolve in response to changes in each other over time is called coevolution. The relationship between two coevolving organisms often becomes so specific that neither organism can survive without the other. Thus, an evolutionary change in one organism is usually followed by a change in the other organism.
Table of Contents
- Formulas and Equations
- Applying Formulas and Equations
- Mean, Median, and Mode
- Estimation
- Using Measurements in Calculations
- Effects of Measurement Errors
- Accuracy
- Precision
- Comparing Accuracy and Precision
- Significant Figures
- Calculating With Significant Figures
- Scientific Notation
- Calculating With Scientific Notation
- Dimensional Analysis
- Applying Dimensional Analysis