Senecio as a model system for integrating studies of genotype, phenotype and fitness

Abstract

Summary Two major developments have made it possible to use examples of ecological radiations as model systems to understand evolution and ecology. First, the integration of quantitative genetics with ecological experiments allows detailed connections to be made between genotype, phenotype, and fitness in the field. Second, dramatic advances in molecular genetics have created new possibilities for integrating field and laboratory experiments with detailed genetic sequencing. Combining these approaches allows evolutionary biologists to better study the interplay between genotype, phenotype, and fitness to explore a wide range of evolutionary processes. Here, we present the genus Senecio (Asteraceae) as an excellent system to integrate these developments, and to address fundamental questions in ecology and evolution. Senecio is one of the largest and most phenotypically diverse genera of flowering plants, containing species ranging from woody perennials to herbaceous annuals. These Senecio species exhibit many growth habits, life histories, and morphologies, and they occupy a multitude of environments. Common within the genus are species that have hybridized naturally, undergone polyploidization, and colonized diverse environments, often through rapid phenotypic divergence and adaptive radiation. These diverse experimental attributes make Senecio an attractive model system in which to address a broad range of questions in evolution and ecology.

Climate Vulnerability Assessment of the Espeletia Complex on Páramo Sky Islands in the Northern Andes

“…However, in order to gather a more comprehensive view of climate change responses in the high mountain ecosystems of the northern Andes, other diverse and highly abundant plant genera in the Páramo (Hughes et al, 2013) should be considered under a similar analytical framework as the described here. Immediate candidates to follow up this approach are Bartsia (Uribe-Convers and Tank, 2015), Chusquea (Ely et al, 2019), Diplostephium (Vargas et al, 2017), Hypericum (Nürk et al, 2013), Loricaria (Kolar et al, 2016), Lupinus (Hughes and Eastwood, 2006;Vásquez et al, 2016;Contreras-Ortiz et al, 2018), Oreobolus (Chacón et al, 2006;Gómez-Gutiérrez et al, 2017), Puya (Jabaily and Sytsma, 2013), and Senecio (Duskova et al, 2017;Walter et al, 2020). These combined efforts would ultimately reveal whether the fastest evolving biodiversity hotspot on earth, and in general tropical high mountain ecosystems (Hedberg, 1964;Sklenáø et al, 2014;Chala et al, 2016), have a chance to persist under current environmental and anthropogenic threats.…”

Linking population‐level and microevolutionary processes to understand speciation dynamics at the macroevolutionary scale

“…A scenario where speciation is driven by geographic opportunities mediated by environmental heterogeneity involves the range expansion of a species and the adaptation of its populations to spatially distributed adaptive peaks (e.g., Gavrilets & Vose, 2005;Wang & Bradburd, 2014). Those adaptive peaks could either reflect variability in resources, such as prey types, but also in habitat and climatic conditions (e.g., Walter et al, 2020). Here, speciation occurs in the presence of gene flow (parapatric speciation, Coyne & Orr, 2004;Rundell & Price, 2009).…”

“…Geographic and resource-partitioning opportunities comprise together important aspects underlying radiations (e.g., Aguilée et al, 2018;Costa et al, 2019;Herrera-Alsina et al, 2018;Kennedy et al, 2018;Stroud & Losos, 2016). As mentioned above, geographic opportunities are tied to the importance of the geographical area and range expansion in promoting speciation, and are probably underlying several radiations, including continental ones, from dinosaurs (O'Donovan et al, 2018) to plants (Walter et al, 2020). On the other hand, resource-partitioning opportunities are frequently associated with sympatric speciation also contributing to the unfolding of radiations, especially those that are restricted in area, such as lakeassociated fishes (e.g., Kautt et al, 2012;Martin & Feinstein, 2014).…”

“…If this limit is absent, opportunities to speciate will not be limited and the radiation will keep constantly generating species (lower left corner in Figure 2b). This rapid diversification scenario, where both the time of expansion and the time that reproductive isolation takes to evolve are short, might represent the process underlying population differentiation along environmental gradients in different taxa (e.g., Friis et al, 2018;Hecht et al, 2015;Walter et al, 2020). The Oregon Junco, for example, has diverged less than 15.000 years ago, already has a distribution encompassing a wide latitudinal range (from Baja California to Alaska), and also shows high population differentiation across space (Friis et al, 2018) 2a,b), we would still be able to see an increase in speciation rates.…”

Dysfunction of CYC2g is responsible for the evolutionary shift from radiate to disciform flowerheads in the Chrysanthemum group (Asteraceae: Anthemideae)

“…Shifts among different types of flowerhead have occurred not only repeatedly among distant lineages across the Asteraceae phylogeny, but also frequently within many recently radiating groups (Bello et al, 2013; Ford and Gottlieb, 1990; Lowe and Abbott, 2000; Nakagawa and Ito, 2014; Sun and Ganders, 1990; Walter et al, 2020). Investigating variations within one species or among closely related species from the microevolutionary viewpoint may provide insights on how changes or innovation of phenotypes have arisen on the macroevolutionary scale.…”