The species Charadrius semipalmatus and Charadrius collaris are from the Plovers group
(Charadriidae Family). These species are migratory and non-migratory birds, respectively. In
the migratory birds, the hippocampus is important to recover memories related to the stopping
places, details about the breeding and the wintering grounds. The hippocampus plays an
important role the processing of spatial memory in these organisms, making them excellent
models to investigate the effect of behavior in this brain region.This work aims to investigate
whether the hippocampal adaptive responses to migratory behavior are related to the migration
and/or evolutionary pattern between migrant and non-migrant species of Charadrius genus.
The individuals of C. collaris and C. semipalmatus were collected in islands of the coast using
mist nets. The birds were measured, anesthetized, identified at species level using
morphological features, had samples of muscle tissue collected and were transcardially
perfused. The brain was cut in the coronal plane, the sections were stained by the Nissl
technique and immunolabelled for NeuN, DCX and C-fos.Cell numbers, hippocampal volume
and cell volume were estimated through the Optical Fractionator, Cavalieri Estimator and
Nucleator, respectively. The total DNA was extracted for subsequent sequencing of the
cytochrome oxidase c subunit I fragment (COI) to generate phylogenetic trees of Bayesian
inference, maximum likelihood, genetic distance measurements and analyzes of phylogenetic
independent contrasts. The results showed that the anatomy of the hippocampal formations
observed in C. semipalmatus and C. collaris corroborate that observed for birds in general.The
stereological results evidenced that the migratory species had higher volume of hippocampal
formation, number of mature neurons and neurogenesis, when compared to non-migratory
species, however there was no difference in the volume of neurons and C-fos positive cells.
Molecular results showed no correlation between the characteristics of the hippocampal
formation and the evolutionary distances between migrant and non-migrant birds, indicating
that the differences in the number of cells as well as the volume of hippocampal formation do
not occur due to the phylogenetic distance between the species. Therefore, the existence of
neuroanatomic differences in the hippocampal formation of migrant birds is evident, excluding
evolutionary factors as responsible for these architectural arrangements.
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