Niche dynamics in amphitropical desert disjunct plants: Seeking for ecological and species‐specific influences

Abstract

Aim Numerous studies have assessed whether species niches are conserved in geographically separated regions. However, most of them were performed on invasive species, with the limitation that such species have likely not yet reached their potential distribution in the invaded region. Here we test the hypothesis of niche conservatism in the entire group of 25 amphitropical desert disjunct plant species, naturally distributed in North and South America but absent in the tropics. We also assessed the influence of ecological (intensity of biotic interactions) and species‐specific factors (dispersal ability and adaptation to stress) on species niche differentiation between the two continents. Location North America and South America. Time period Recent. Major taxa studied Plants. Amphitropical desert disjunct species. Methods Species’ presence coordinates and five biologically relevant climatic variables were used to quantify niche differentiation of species between continents by means of principal component analysis. Then, structural equation modelling was performed to assess the influence on niche differentiation of proxies for intensity of biotic interactions (habitat net primary productivity), species dispersibility (dispersal mode and plant traits), and adaptation to stress (leaf size). Results Niche shift was detected for 24 out of the 25 species, mostly towards cooler environments in South America (−2.5 °C average) with respect to North America. These niche shifts were best explained by the productivity of species’ habitats, in particular by the displacement of species’ niches away from the more productive and competitive environments of South America. Main conclusions Niche shift seems to be the rule in amphitropical desert plants. Our findings highlight a previously undetected connection between amphitropical disjunct species and macroecological characteristics of the Americas. We show that prevalent environments differ between South and North America, and suggest that associated biotic contexts (mainly competition from widespread tropical and subtropical forests in South America) play a determinant role on species’ distribution and niches.

The South Asian monsoon maintains the disjunction of Rumex hastatus between the western Himalayas and the Hengduan Mountains, southwest China

“…Wasof et al (2015) concluded that the realized niches of disjunct arctic‐alpine plants in the Alps and Fennoscandia have largely been conserved since their population fragmentation after the LGM. In contrast, niches of desert plant species that are disjunctly distributed in North and South America were found to be at disequilibrium in terms of thermal preferences, which could have shifted to avoid competition at more productive sites (Quiroga et al 2021). In fact, HIM sites of R. hastatus are somewhat colder and exhibit a more continental climate than sites in the HDM (Miehe et al 2001).…”

Evolutionary origins of the eastern North American–Mesoamerican floristic disjunction: Current status and future prospects

“…Such shared disjunctions offer an unparalleled opportunity to reconstruct how geologic history has shaped the assembly of modern plant communities. More broadly, they also represent excellent systems for studying myriad fundamental processes in ecology and evolution, including speciation and diversification (Xiang et al, 2004; Yang et al, 2018), niche evolution (Wasof et al, 2015; Melton et al, 2022), biotic interactions (Quiroga et al, 2020), community assembly (Donoghue and Smith, 2004; Donoghue, 2008; Manos and Meireles, 2015; Dick and Pennington, 2019; Jiang et al, 2019), and evolutionary responses to climate change over both small and larger time scales (Qian and Ricklefs, 2004; Hamilton and Eckert, 2007; Kuhn et al, 2016).…”

Towards causal relationships for modelling species distribution

“…However, due to technical limitations such as the application of SEM to data not fitting a Gaussian error distribution and the estimate of only linear relationships prevented a broader application of this methodology to data types commonly found in ecological studies (Grace, 2022; Lefcheck, 2016). Recent technical developments overcome some of these limitations (e.g., Carvalho‐Rocha et al., 2021; Cerqueira et al., 2021; Chu et al., 2019; Quiroga et al., 2021; Walentinowitz et al., 2023), but their application into SDMs remains surprisingly low.…”