Neotropical refugia

Patterns of endemism in the Neotropics have been explained by restriction of forest to ‘refugia’ in arid cold-stages of the Quaternary (Haffer J (1969)<br/>Speciation in Amazonian forest birds. Science 165: 131–137). The palaeoecological record, however, shows no such forest contraction. We review<br/>palaeoecological and phylogenetic data on the response of Neotropical taxa and communities to climatic changes of the Cenozoic. Solar insolation varies<br/>over this period with latitude and geography, including shifts in opposite directions between high and low latitudes. In the Neotropics, distribution and<br/>abundance patterns originate on a wide range of timescales through the Cenozoic, down to the currently dominant precession forcing (20 kyr). In contrast,<br/>distributions and abundances at higher latitudes are controlled by obliquity forcing (40 kyr). The patterns observed by Haffer (1969) are likely derived<br/>from pre-Quaternary radiations and are not inconsistent with palaeoecological findings of continuous forest cover in major areas of the Neotropics<br/>during the Quaternary. The relative proportions of speciation processes have changed through time between predominantly sympatric to predominantly<br/>allopatric depending on the prevailing characteristics of orbitally forced climatic changes. Behaviour of Neotropical organisms and ecosystems on long<br/>timescales may be influenced much more by precessional forcing than by the obliquity forcing that controls high-latitude climate change and glaciations.