Biology subjects

Leal, B. S. S.

Publications and source records attributed to Leal, B. S. S..

2 recordsLinked to original sources

bioRxiv2020

Deforestation reduces the genetic structure of an epiphytic weed across space and time: an IBM approach

Deforestation has allowed the massive dispersal and reproduction of some plants that are commonly referred to as weeds. The rapid spread of many weeds into newly disturbed landscapes is often boosted by clonal growth and self-fertilization strategies, which conversely increases the spatial genetic structure (SGS) of populations and reduces the genetic diversity. Here, we use empirical and modeling approaches to evaluate the spatio-temporal SGS dynamics of Tillandsia recurvata (L.) L., a common epiphytic weed with selfing reproduction and clonal growth widespread in dry forests and anthropically deforested landscapes in North and South America. We constructed an individual-based model (IBM) and adjusted the parameters according to empirical genetic data, to simulate the spreading of T. recurvata over time and across random landscapes with distinct tree densities. From empirical data, we observed a strong SGS among T. recurvata subpopulations hosted on neighbor trees and a contemporary spread from several population sources. Our model shows that the highest SGS appear in landscapes with more than 200 trees/ha and up to the 5th year of colonization of open landscapes (ca. 100 trees/ha) when SGS starts to reduce drastically. These results suggest that the deforestation commonly observed in anthropically transformed landscapes may reduce the dispersal limitation and genetic structure of T. recurvata subpopulations, creating suitable conditions for the rapid spread of T. recurvata from multiple surrounding sources. The combination of clonal growth and self-fertilization with the optimal conditions created by anthropogenic transformations may explain the spreading success of T. recurvata and other weeds into new landscapes. Our results indicate that the drastic reductions in tree densities induced by human-modifications in natural landscapes may lead to a partial loss of resistance for dispersal by wind and increased the conditions for T. recurvata to develop massive populations in anthropogenic landscapes.

ecology↗

bioRxiv2020

Underlying microevolutionary processes parallel macroevolutionary patterns in ancient Neotropical Mountains

AimThe exceptional species-richness associated with mountains worldwide is linked to the fragmented topography of these areas, responsible for constantly isolating populations during periods of climatic fluctuations. Consequently, endemism and spatial turnover in mountains are very high and few species are widespread among entire mountain ranges, precluding population-level studies that help understanding how macroevolutionary patterns were shaped. Here, we used the bromeliad Vriesea oligantha, a species endemic to, but widespread in, one of the most species-rich ancient montane areas in the globe, the Espinhaco Range, to test how environmental changes over time may have acted on the evolutionary history of this taxon, contributing to understanding how montane macroevolutionary patterns were shaped. Through analyses of plastidial and nuclear DNA of V. oligantha, we dated its origin and intraspecific diversification, and estimated the genetic diversity, structure and migration rates among populations. Using climatic and geographic variables, we modeled suitable areas for the present and the past, estimating corridors between isolated populations. We also used demographic analyses to estimate ancient population dynamics of V. oligantha. Finally, we tested whether climatic variables or geographical distance explain the observed population structure. The origin and intraspecific diversification of V. oligantha are related to early climatic oscillations during the Plio-Pleistocene. This species has a high population structure due to its low pollen and seed dispersibility. The analysis of species distribution modeling estimated corridors between populations in the past, whereas the structure of V. oligantha results from both models of isolation by distance and isolation by environment. The phylogeographic patterns of Vriesea oligantha reflect previously recognized spatial and temporal macroevolutionary patterns in the Espinhaco Range, providing insights into how microevolutionary processes may have given rise to this astonishing mountain biodiversity.

evolutionary biology↗