Another response to environmental change is to evolve structures and behaviors that can be used to cope with different environments. The selection of these structures and behaviors as a result of environmental instability is known as variability selection. This hypothesis differs from those based on consistent environmental trends. Environmental change in an overall direction leads to specializations for those specific conditions. But if the environment becomes highly variable, specializations for particular environments would be less advantageous than structures and behaviors that enable coping with changing and unpredictable conditions. Variability selection refers to the benefits conferred by variations in behavior that help organisms survive change. To test the variability selection hypothesis, and to compare it with habitat-specific hypotheses, Potts examined the hominin fossil record and the records of environmental change during the time of human evolution.
3. To simplify the complex to make it manageable or understandable. Almost all models are simplifications because reality is so complex. The whole economy, weather system, human personality, geological structure of the earth, air flow over airplane wings--all are too complex to be treated as is, so models are constructed that present simplifications that can be treated. Simplification is both benefit and danger, and when dealing with a model, one must always be sure not to forget that the model and reality might not match perfectly--and sometimes not well at all.
Null and Alternative Hypothesis | Real Statistics Using …
The ecological functions of birds (Sekercioglu 2006) -- Birds are mobile links that are crucial for maintaining ecosystem function, memory and resilience. Avian ecological functions encompass all three major linkages: genetic, resource and process. Seed-dispersing frugivores and pollinating nectarivores are genetic linkers that carry genetic material from one plant to another or to habitat that is suitable for regeneration, respectively. Piscivorous birds are resource linkers whose droppings transport aquatic nutrients to terrestrial environments. Grazers, such as geese, and predatory birds, such as insectivores and raptors are trophic process linkers that influence plant, invertebrate and vertebrate prey populations, respectively. Ecosystem engineers, such as woodpeckers are non-trophic process linkers that modify their environment by physically transforming materials from one state to another. Mobile link categories are not mutually exclusive. Birds, particularly colonial species (e.g. social weavers ) and woodpeckers, can modify their environment substantially by constructing nests, which are often used by a variety of other species. Thus, many bird species are both trophic and physical process linkers. Piscivorous bird colonies can carry out all of these linkages as these birds can consume fish, deposit nutrients, engineer ecosystems via burrow construction and even disperse seeds that are adhered to their feet.