Why is Amazonia a ‘source’ of biodiversity? Climate-mediated dispersal and synchronous speciation across the Andes in an avian group (Tityrinae)

Abstract

Amazonia is a ‘source’ of biodiversity for other Neotropical ecosystems, but which conditions trigger in situ speciation and emigration is contentious. Three hypotheses for how communities have assembled include (1) a stochastic model wherein chance dispersal events lead to gradual emigration and species accumulation, (2) diversity-dependence wherein successful dispersal events decline through time due to ecological limits, and (3) barrier displacement wherein environmental change facilitates dispersal to other biomes via transient habitat corridors. We sequenced thousands of molecular markers for the Neotropical Tityrinae (Aves) and applied a novel filtering protocol to identify loci with high utility for dated phylogenomics. We used these loci to estimate divergence times and model Tityrinae's evolutionary history. We detected a prominent role for speciation driven by barriers including synchronous speciation across the Andes and found that dispersal increased toward the present. Because diversification was continuous but dispersal was non-random over time, we show that barrier displacement better explains Tityrinae's history than stochasticity or diversity-dependence. We propose that Amazonia is a source of biodiversity because (1) it is a relic of a biome that was once more extensive, (2) environmentally mediated corridors facilitated emigration and (3) constant diversification is attributed to a spatially heterogeneous landscape that is perpetually dynamic through time.

A Multireference-Based Whole Genome Assembly for the Obligate Ant-Following Antbird, Rhegmatorhina melanosticta (Thamnophilidae)

“…For example, collaborative endeavours to sequence thousands of bird (Bird10K project [2]) and other vertebrate genomes (Genome10K project [3]) across many countries and research groups have been launched in the past decade, and have produced promising results [4][5][6][7]. Thus, high-throughput sequencing has rapidly improved our ability to make robust inferences in various fields, including avian systematics [7][8][9], population genomics and phylogeography [10][11][12][13][14][15][16], biogeography [17,18], molecular evolution [19], and speciation [20]. There has been an especially rapid increase in the number of studies specifically using whole-genome sequencing (often combined with reduced representation approaches) to answer difficult ornithological questions [7,[20][21][22][23].…”

“…Among birds, few groups have been as important to understanding biotic diversification and macroevolutionary process than the New World suboscines (suborder Tyranni), which contain an enormous level of taxonomic, ecological, and functional diversity [17,18,[42][43][44][45][46][47][48]. Within this group, the army ant-following clade, which includes multiple genera (Rhegmatorhina, Gymnopythis, Willisornis, Phaenostictus, Phlegopsis, and Pythis) has enamored researchers for decades and formed the foundation of many ecological, phylogeographic, biogeographic, and population genetic studies [47,[49][50][51][52][53][54].…”

Mesoamerica is a cradle and the Atlantic Forest is a museum of Neotropical butterfly diversity: Insights from the evolution and biogeography of Brassolini (Lepidoptera: Nymphalidae)

“…The Pebas wetland might in fact have increased opportunities for dispersal across Amazonia and diversification of some typical coastal plants (Bernal et al ., 2019), including many of the Brassolini’s hostplants in the region: Arecaceae (palms), Poaceae (bamboos), and Zingiberales such as Marantaceae (Beccaloni et al ., 2008; Janzen et al ., 2009). It is plausible that the evolutionary consequences of the Miocene marine incursions in western Amazonia might have been mixed and rather ephemeral (Musher et al ., 2019), restricting dispersal and diversification in some butterfly lineages such as Ithomiini (Chazot et al ., 2019b) while providing ecological opportunities for diversification of others, such as Brassolini.…”

Asynchronous diversification and distinct demographic trajectories in Ethiopian montane forest bird (Aves: Passeriformes) populations separated by the Great Rift Valley

“…An ongoing question in evolutionary biology is whether taxa differentiate in communities in response to extrinsic forces for example, geographic or climatic change or in species-specific manners based on their intrinsic characteristics such as physiological thermal tolerance or dispersal ability. In speciation scenarios dominated by geologic or climatic change, entire communities may differentiate in pulses synchronous with the changes in the Earth's template (e.g., Barber & Klicka 2010;Musher et al 2019;O'Connell et al 2018). In contrast, when communities have species that vary in dispersal ability, niche breadth, or population history, diversification may be asynchronous across taxa based on those species' intrinsic characteristics (e.g., Naka & Brumfield 2018;Oswald et al2017;Papadopoulou et al 2009).…”