Biology subjects

Loiseau, O.

Publications and source records attributed to Loiseau, O..

3 recordsLinked to original sources

bioRxiv2022

Precipitation is the main axis of tropical phylogenetic turnover across space and time

Early natural historians - Compte de Buffon, von Humboldt and De Candolle - established ecology and geography as two principal axes determining the distribution of groups of organisms, laying the foundations for biogeography over the subsequent 200 years, yet the relative importance of these two axes remains unresolved. Leveraging phylogenomic and global species distribution data for Mimosoid legumes, an pantropical plant clade of 3,400 species, we show that the water availability gradient from deserts to rainforests dictates turnover of lineages within continents across the tropics. We demonstrate that 95% of speciation occurs within a precipitation niche, showing profound phylogenetic niche conservatism, and that lineage turnover boundaries coincide with isohyets of precipitation. We reveal similar patterns on different continents, implying that evolution and dispersal follow universal processes.

evolutionary biology↗

bioRxiv2021

Diversity and Divergence: Evolution of defense chemistry in the tropical tree genus Inga

O_LIPlants are widely recognized as chemical factories, with each species producing dozens to hundreds of unique secondary metabolites. These compounds shape the interactions between plants and their natural enemies. Here we explore how plants generate chemical diversity, and what evolutionary processes have led to novel compounds and unique chemical profiles. C_LIO_LIWe comprehensively characterized the chemical profile of one-third of the species of tropical rainforest trees in the genus Inga ([~] 100, Fabaceae) and applied phylogenetic comparative methods to understand the mode of chemical defense evolution. C_LIO_LIWe show that: 1) Each Inga species produces exceptionally high levels of phytochemical diversity, despite costs, tradeoffs and biosynthetic constraints. 2) Closely related species have highly divergent defense profiles, with individual compounds, major compound classes and complete profiles showing little to no phylogenetic signal. 3) We show that the evolution of a species chemical profile shows a signature of divergent adaptation, implying that it is advantageous for a species to have distinct chemistry from close relatives to avoid shared natural enemies. 4) Finally, we hypothesize a model where deep homology of biosynthetic pathways and rapid changes in regulatory mechanisms may better explain the observed large shifts in defense chemicals between closely related taxa. C_LI

evolutionary biology↗

bioRxiv2017

Evolutionary history of New World monkeys revealed by molecular and fossil data

New World monkeys (parvorder Platyrrhini) are one of the most diverse groups of primates, occupying today a wide range of ecosystems in the American tropics and exhibiting large variations in ecology, morphology, and behavior. Although the relationships among the almost 200 living species are relatively well understood, we lack robust estimates of the timing of origin, the ancestral morphology, and the evolution of the distribution of the clade. Here we integrate paleontological and molecular evidence to investigate the evolutionary dynamics of extinct and extant platyrrhines. We develop an analytical framework to infer ancestral states, the evolution of body mass, and changes in latitudinal ranges through time. Our results show that extant platyrrhines originated some 5-10 million years earlier than previously assumed, likely dating back to the Middle Eocene ([~] 43 million years ago, Ma). The estimated ancestral platyrrhine was strikingly small - weighing [~] 0.4 kg, as compared to the largest modern species over 10 kg - matching the size of their presumed Eocene North African ancestors. Small-sized callitrichines (marmosets and tamarins) retained a small body mass throughout their evolutionary history, thus challenging the hypothesis of phyletic dwarfism as an explanation to their adaptive traits. In contrast, a rapid change in body mass range took place as the three families diverged between the Late Oligocene and the Early Miocene. That period also marks a peak in diversity of fossil platyrrhines and is associated with their widest latitudinal range, expanding as far to the South as Patagonia. This geographic expansion is temporally coincident with a significant increase in platyrrhine population size inferred from genomic data, and with warm and humid climatic conditions linked to the Miocene Climatic Optimum and the lower elevation of the Andes. These results unveil the early evolution of an iconic group of monkeys and showcase the advantages of integrating fossil and molecular data for estimating evolutionary rates and trends.

evolutionary biology↗