Population dynamics of Amazonian floodplain forest species support spatial variation on genetic diversity but not range expansions through time

Aim: We tested if historical demographic changes of populations occurring
on the floodplains of a major Amazon Basin tributary could be associated
with range expansions from upper and middle sections of the river,
following the establishment of widespread river-created environments
during the Late Pleistocene and Holocene. Location: Solimões River,
Western Amazon, South America. Taxon: Myrmoborus lugubris, Thamnophilus
cryptoleucus and Myrmotherula assimilis. Methods: We explored spatial
patterns of genetic diversity and connectivity among sampled localities
using thousands of Ultra-Conserved Elements. Range expansions were tested
with alternative methods. We quantified habitat preference for the
analyzed species to test whether the occupation of dynamic habitats could
predict spatial patterns of genetic diversity. Results: Our study did not
support shared population range expansions related to historical
regionalized changes in habitat availability. We found considerable
variation in the spatial distribution of the genetic diversity between
studied taxa, and that species with higher levels of specialization to
dynamic environments have a more heterogeneous distribution of genetic
diversity and reduced levels of gene flow across space. Main conclusions:
Our results suggest that demographic expansions along the Solimões River
might be linked to spatially homogeneous oscillation in the distribution
of floodplain environments, promoting effective population size changes
but not range expansion. We found that habitat specificity might be a good
predictor of population connectivity along the Amazonian floodplains.