The spatial genetic structure of the White‐banded Tanager (Aves, Passeriformes) in fragmented Neotropical savannas suggests two evolutionarily significant units

Abstract

Understanding the genetic structure of a species is crucial for evolutionary biology research and species conservation. The objectives of this study were to investigate the genetic structure of Neothraupis fasciata in Brazilian savannas and to assess genetic differentiation of its disjunct population in the Amazonian savannas of the state of Amapá. Population genetic structure was assessed in relation to isolation by distance and landscape variables connected with habitat heterogeneity. The influences of factors, such as habitat fragmentation and core–periphery distribution, on genetic diversity were also examined. Data were derived from a set of microsatellite loci of adult individuals from nine localities: eight distributed across the Cerrado and one in the disjunct Amazonian savanna of Amapá. Analysis revealed moderate genetic diversity and moderate population genetic structure, with at least two genetic clusters, one of which is represented exclusively by the disjunct Amapá population. The genetic structure found is not the result of significant influences by geographical distance, habitat heterogeneity, or the core–periphery effect, nor by intense biome fragmentation due to anthropic action. The disjunct Amapá population exhibited a moderate level of genetic differentiation compared to the Cerrado population, suggesting that both can be considered distinct evolutionarily significant units for conservation purposes. Abstract in Portuguese is available with online material.

Late Pleistocene climatic changes promoted demographic expansion and population reconnection of a Neotropical savanna-adapted bird, Neothraupis fasciata (Aves: Thraupidae)

“…This is an unexpected result, given the low dispersal from the birth area reported for this species (around 300 meters; [37]). However, a previous study of the genetic structure of this tanager using microsatellite markers also found no effect of geographic distance under the genetic differentiation among these same sampled locations [39]. The isolation-by-distance pattern occurs when the migration-drift equilibrium is reached, but it can take a relatively long time [79].…”

“…A previous study using a set of microsatellite markers found moderate genetic structure in N . fasciata and the distribution of the genetic variability was not explained by the isolation-by-distance hypothesis, habitat heterogeneity or by the core-periphery effect [ 39 ]. Similarly, the intense biome fragmentation by anthropic activity has not contributed significantly to the current pattern of genetic structure found in this species [ 39 ].…”

“…fasciata and the distribution of the genetic variability was not explained by the isolation-by-distance hypothesis, habitat heterogeneity or by the core-periphery effect [ 39 ]. Similarly, the intense biome fragmentation by anthropic activity has not contributed significantly to the current pattern of genetic structure found in this species [ 39 ]. These findings suggest the influence of historical processes on the distribution of genetic diversity of this tanager.…”

Ecological traits drive genetic structuring in two open‐habitat birds from the morphologically cryptic genus Elaenia (Aves: Tyrannidae)

“…Most previous studies of differentiation in Neotropical birds from open areas have found evidence for Pleistocene climatic oscillations as a driver of intraspecific divergence (Lima-Rezende et al 2019b, Rocha et al 2020, Ritter et al 2021. For instance, the genetic differentiation of narrowbilled woodcreeper Lepidocolaptes angustirostris populations seems to have occurred in allopatry in stable areas that formed during Pleistocene climatic fluctuations (Rocha et al 2020).…”

Geographic isolation reduces genetic diversity of a wide‐ranging terrestrial vertebrate, Canis lupus

“…Our objective was thus twofold: to determine if geographic patterns of genetic diversity in North American gray wolves are consistent with the CMH, and to assess how the predicted edge effect interacts with the island effect. To that end, we tested how population genetic diversity varies in relation to two indices of the edge effect—latitude (Castellanos‐Morales et al, 2014; De Kort et al, 2021; Jenkins et al, 2018; Rodríguez‐Rodríguez et al, 2015; Wultsch et al, 2016) and distance to the center of the species' range (Langin et al, 2017; Lima‐Rezende et al, 2019; Natesh et al, 2017; Trumbo et al, 2016)—and we evaluated how these relationships are modified by island habitation.…”