Multistage life cycles allow full use of habitats that are ephemeral in space or time. Generally, these more r-selected species are able to colonize new areas much faster than ^-selected species. Thus, they are often early pioneers in succession. Some of this mobility is due to the age structuring itself. For example, seeds can lie dormant for years until ecological conditions initiate germination and development into adult plants. Similar dormant phases are seen in many invertebrates and this phenomenon is called the 'storage effect'. Age structuring in such species allows the species to persevere in an area despite extremely adverse environmental conditions, and thus allows the population to rapidly grow in the area when conditions again become favorable. Such an age-structure effect on population dynamics is a significant advantage over species which maintain a similar life form in all age classes; the latter may be lost from the area during adverse periods if adverse conditions last longer than a generation, and would be dependent upon dispersal from favorable areas to recolonize. An age structure comprised of distinct life forms, especially if one or more is capable of extended dormancy, allows rapid population responses during favorable periods and is thus a significant advantage for early successional or pioneer species, or for species existing on the fringe of habitable conditions. Similarly, highly mobile life stages allow rapid colonization ofhabitats even if no 'storage effect' is present.
Was this article helpful?