Isolation drives increased diversification rates in freshwater amphipods

Publication date: Available online 27 June 2018Source: Molecular Phylogenetics and EvolutionAuthor(s): Nicole E. Adams, Kentaro Inoue, Richard A. Seidel, Brian K. Lang, David J. BergAbstractVicariance and dispersal events affect current biodiversity patterns in desert springs. Whether major diversification events are due to environmental changes leading to radiation or due to isolation resulting in relict species is largely unknown. We seek to understand whether the Gammarus pecos species complex underwent major diversification events due to environmental changes in the area leading either to radiation into novel habitats, or formation of relicts due to isolation. Specifically, we tested the hypothesis that Gammarus in the northern Chihuahuan Desert of New Mexico and Texas, USA are descendants of an ancient marine lineage now containing multiple undescribed species. We sequenced a nuclear (28S) and two mitochondrial (16S, COI) genes from gammarid amphipods representing 16 desert springs in the northern Chihuahuan Desert. We estimated phylogenetic relationships, divergence times, and diversification rates of the Gammarus pecos complex. Our results revealed that the region contained two evolutionarily independent lineages: a younger Freshwater Lineage that shared a most-recent-common-ancestor with an older Saline Lineage ∼66.3  MYA (95.6–42.4  MYA). Each spring system generally formed a monophyletic clade based on the concatenated dataset. Freshwater Lineage diversifi...

Source: Molecular Phylogenetics and Evolution - July 10, 2018 Category: Molecular Biology Source Type: research