DOI: 10.1111/jbi.70362 ISSN: 0305-0270
Phylogeographic Patterns of the
Eigenmannia humboldtii
Group Shaped by Miocene‐Pleistocene Transitions
Weverton John P. Santos, Luiz Antônio W. Peixoto, Bianca L. Paiva, Alan Erik S. Rodrigues, Claudio Oliveira, José Augusto P. Bitencourt, Tiberio Cesar T. Burlamaqui, Jonathan S. Ready, João Bráullio de Luna Sales ABSTRACT
Aim
Eigenmannia
is a monophyletic genus of small and medium‐sized fishes known as ‘glass knifefishes’, with a wide distribution throughout the Neotropical region and a complex taxonomic history. This study aimed to investigate the phylogenetic diversification patterns within the
Eigenmannia humboldtii
species group (specifically
E. nigra
and
E. limbata
), using mitochondrial and nuclear markers to evaluate the existence of geographically structured evolutionary lineages.
Location
Neotropical Region.
Taxon
Eigenmannia nigra
and
Eigenmannia limbata
(Teleostei: Gymnotiformes: Sternopygidae).
Methods
DNA from available specimens identified as
E. nigra
and
E. limbata
, from different localities, was extracted and fragments of mitochondrial genes (
coxI
,
CytB
and
rrnl
) and a nuclear gene (
Zic1
) were amplified and sequenced. Concatenated alignments were generated to estimate divergence times (TMRCA) and for Ancestral State Reconstruction in Phylogenies (RASP). Species delimitation based on the
coxI
marker was carried out using ASAP, PTP and bPTP.
Results
The results indicate the existence of different lineages within
E. nigra
and
E. limbata
, originating in the Middle Miocene (~12.22 mya) and undergoing sequential diversification until the Pliocene (~4.31 mya)/Pleistocene (~1.77 mya). The analyses suggest that lineage diversification is broadly consistent with major episodes of Amazonian drainage reorganization, including Andean uplift, the transition from the Pebas–Acre systems to modern fluvial networks, and the establishment of hydrological barriers among the Brazilian Shield, Guiana Shield and western Amazonian drainages.
Main Conclusions
These findings indicate that major Neogene landscape changes in Amazonia, including drainage reorganization and the progressive isolation of shield and lowland basins, were important drivers of lineage diversification and dispersal in
E. nigra
and
E. limbata
. The recovery of multiple drainage‐restricted evolutionary lineages supports a close association between Amazonian hydrographic evolution and fine‐scale geographic structuring within these species complexes.