Understanding the factors that explain the patterns of genetic structure or phylogeographic breaks at an intraspecific level is key to inferring the mechanisms of population differentiation in its early stages. These topics have been well studied in the Baja California region, with vicariance and the dispersal ability of individuals being the prevailing hypothesis for phylogeographic breaks. In this study, we evaluated the phylogeographic patterns in the desert iguana (Dipsosaurus dorsalis), a species with a recent history in the region and spatial variation in life history traits. We analyzed a total of 307 individuals collected throughout 19 localities across the Baja California Peninsula with 15 microsatellite DNA markers. Our data reveal the existence of 3 geographically discrete genetic populations with moderate gene flow and an isolation-by-distance pattern presumably produced by the occurrence of a refugium in the Cape region during the Pleistocene Last Glacial Maximum. Bayesian methods and ecological niche modeling were used to assess the relationship between population genetic structure and present and past climatic preferences of the desert iguana. We found that the present climatic heterogeneity of the Baja California Peninsula has a marked influence on the population genetic structure of the species, suggesting that there are alternative explanations besides vicariance. The information obtained in this study provides data allowing a better understanding of how historical population processes in the Baja California Peninsula can be understood from an ecological perspective.

Effective cetacean conservation depends on robust monitoring, yet traditional visual and passive-acoustic surveys have constraints. We evaluated environmental DNA (eDNA) metabarcoding coupled with species distribution modeling (SDM) as a tool to study habitat use of cetaceans along the Washington State coast, USA. Seawater was collected at the surface and at a 50 m depth from 43 sites (86 samples) during the 2019 U.S.–Canada Integrated Ecosystem & Acoustic-Trawl Survey. A partial section of the mitochondrial control region was amplified with cetacean - specific primers, sequenced on an Illumina MiSeq, and taxonomically assigned with a curated reference database. Nine species were detected; we modelled the three most frequent: Pacific white-sided dolphin ( Lagenorhynchus obliquidens ) (10 detections), humpback whale ( Megaptera novaeangliae ) (8 detections), and Risso’s dolphin ( Grampus griseus ) (6 detections). Binomial generalized additive models related presence-absence to bathymetry, distance to shore, longitude, slope, and sea-surface temperature; model performance was assessed with stratified five-fold cross-validation. SDMs explained 17–51% of null deviance and presented high specificity (≥ 0.80). The Pacific white-sided dolphin showed the highest eDNA presence probabilities offshore, beyond the shelf break. Humpback whale eDNA presence probabilities showed hotspots along the shelf break with secondary high-probability patches in near-shore waters. Risso’s dolphin eDNA presence probabilities were elevated in offshore zones characterized by steep bathymetric gradients, particularly northwest of the sampled transect. These spatial patterns are consistent with historical visual–acoustic records, suggesting that eDNA-informed SDMs can capture cetacean habitat use. This proof of concept indicates that combining eDNA detections with flexible SDMs could provide a cost-effective, non-invasive complement to conventional surveys and may offer a scalable pathway for marine-mammal monitoring and spatial planning.