Forecasts of climate-driven habitat suitability distribution are complicated by taxonomic and cytogenetic complexity in Rhexia (Melastomataceae).

Rhexia (Melastomataceae), a temperate genus composed of 13 species in eastern North America, provides a useful system for evaluating how taxonomic and cytogenetic complexity influence forecasts of climate-driven habitat suitability distribution. Ecological niche models incorporating climatic and edaphic variables were used to estimate current and future habitat suitability for diploid, polyploid, and mixed-cytotype species. Habitat suitability was strongly associated with soil texture, hydrological conditions, and precipitation, with suitable environments characterized by sandy, acidic, and seasonally moist habitats. Projections under future climate scenarios revealed highly variable, species-specific responses, with some taxa exhibiting substantial expansions in the distribution of suitable habitat and others experiencing pronounced contractions. Contrary to expectations, ploidal level was not consistently associated with niche breadth or climate response, as both diploid and polyploid species displayed a wide range of outcomes. These findings highlight the need for flexible, habitat-focused conservation strategies that consider hydrological and edaphic variables and demonstrate how taxonomic and cytogenetic complexity can complicate forecasts of biodiversity change under future climate scenarios.