Spore traits mediate disturbance effects on arbuscular mycorrhizal fungal community composition and mutualisms

Jacob R. Hopkins, Alison E. Bennett. 2023. Ecology. https://doi.org/10.1002/ecy.4016

Abstract

Trait-based approaches in ecology are powerful tools for understanding how organisms interact with their environment. These approaches show particular promise in disturbance and community ecology contexts for understanding how disturbances like prescribed fire and bison grazing influence interactions between mutualists like arbuscular mycorrhizal (AM) fungi and their plant hosts. In this work we examined how disturbance effects on AM fungal spore community composition and mutualisms were mediated by selection for specific functional spore traits at both the species and community level. We tested these questions by analyzing AM fungal spore communities and traits from a frequently burned and grazed (bison) tallgrass prairie system and using these spores to inoculate a plant growth response experiment. Selection for darker, pigmented AM fungal spores, changes in the abundance and volume of individual AM fungal taxa, and altered sporulation, were indicators of fire and grazing effects on AM fungal community composition. Disturbance associated changes in AM fungal community composition were then correlated with altered growth responses of Schizachyrium scoparium grass. Our work shows that utilization of trait-based approaches in ecology can clarify the mechanisms that underly belowground responses to disturbance, and provide a useful framework for understanding interactions between organisms and their environment.

Dialect differences correlate with environment in migratory coastal White-crowned Sparrows

Jiaying Yang, Bryan C. Carstens, Kaiya L. Provost. 2023. doi: https://doi.org/10.1101/2023.03.08.531720

Abstract

Vocalization behavior in birds, especially songs, strongly affects reproduction, with differences in vocalizations between populations often interpreted as evidence of divergence. Previous work has demonstrated that the White-crowned Sparrow (Zonotrichia leucophrys) has multiple dialects, including between neighboring (and genetically distinct) subspecies nuttalli and pugetensis. However, it is unknown whether the divergence in their songs correlates to environmental or geographical factors. Previous work has relied on limited amounts of data because traditional methods to study bird songs rely on the manual annotation of song spectrograms into individual syllables. Here we explore the performance of automated machine learning methods of song annotation, which can process large datasets more efficiently, paying particular attention to the question of subspecies differences. We utilize a recently published artificial neural network to automatically annotate hundreds of White-crowned Sparrow vocalizations across two subspecies. By analyzing differences in syllable usage and composition, we find that nuttalli and pugetensis have significantly different dialects. Our results are consistent with the interpretation that these differences are caused by the reduction in the number of shared syllables in the White-crowned Sparrow repertoire, as reported by some previous research. Our large sample size enables us to demonstrate that divergence in dialects is correlated with environmental difference, but not with geographical distance, and is also associated with migratory status. Our findings support the hypothesis that the evolution of vocalization behavior is affected by both biotic and abiotic environments, in addition to population structure.

Geographic isolation and long-distance gene flow influence the genetic structure of the blue fan palm Brahea armata (Arecaceae)

Jessica Pérez-Alquicira, Elisabet V. Wehncke, Gustavo A. García-Loza, Bryan C. Carstens, César A. Domínguez, Rubén Pérez-Ishiwara, Francisco E. Molina-Freaner, María del Pilar Zamora-Tavares, Yessica Rico, Dánae Cabrera-Toledo, Ofelia Vargas-Ponce, Aarón Rodríguez & Exequiel Ezcurra. Journal of Plant Research volume 136, pages 277–290 (2023)

Abstract

The formation of the Baja California Peninsula (BCP) has impacted the microevolutionary dynamics of different species in ways that depend on biological traits such as dispersal capacity. Plants with relatively low levels of vagility have exhibited high genetic divergence between the BCP and Continental mainland. Brahea armata (Arecaceae) is a palm species inhabiting the northern part of the BCP and Sonora; its distribution occurs in isolated oases of vegetation. We aimed to evaluate the influence of the formation of the BCP on the genetic structure of B. armata using nuclear microsatellites and chloroplast markers (cpDNA)  to compare patterns of genetic diversity and structure with previous published studies. Because gene flow through seeds is usually more limited compared to pollen flow, we expect to find stronger genetic structure at (cpDNA) than at nuclear markers. Moreover, larger genetic structure might also be explained by the smaller effective population size of cpDNA. We analyzed six microsatellite markers and two cpDNA regions. The main results indicated high levels of genetic differentiation among isolated populations located in the BCP, while low genetic differentiation was found between southern populations of the BCP and Sonora, suggesting long distance gene flow. In contrast, chloroplast markers indicated high levels of genetic structure between BCP and Sonora populations, suggesting asymmetrical gene flow between pollen (measured by nuclear microsatellites) and seed (cpDNA markers). This study provides valuable information on genetic diversity of B. armata that can be relevant for conservation and management; and develops microsatellites markers that can be transferred to other Brahea species.

The evolution of sanguivory in vampire bats: origins and convergences

Daniel K. and Gerald G. Carter. Canadian Journal of Zoology, Volume 101, Number 4
April 2023. https://doi.org/10.1139/cjz-2022-0115

Abstract

Blood-feeding (sanguivory) has evolved more than two dozen times among birds, fishes, insects, arachnids, molluscs, crustaceans, and annelids; however, among mammals, it is restricted to the vampire bats. Here, the authors revisit the question of how it evolved in that group. Evidence to date suggests that the ancestors of phyllostomids were insectivorous, and that carnivory, omnivory, and nectarivory evolved among phyllostomids after vampire bats diverged. Frugivory likely also evolved after vampire bats diverged, but the phylogeny is ambiguous on that point. However, vampire bats lack any genetic evidence of a frugivorous past, and the behavioural progression from frugivory to sanguivory is difficult to envision. Thus, the most parsimonious scenario is that sanguivory evolved in an insectivorous ancestor to vampire bats via ectoparasite-eating, wound-feeding, or some combination of the two—all feeding habits found among blood-feeding birds today. Comparing vampire bats with other sanguivores, the authors find several remarkable examples of convergence. Further, it was found that blood-feeding has been ca. 50 times more likely to evolve in a vertebrate lineage than in an invertebrate one. The authors hypothesize that this difference exists because vertebrates are more likely than invertebrates to have the biochemical necessities required to assimilate the components of vertebrate blood.

Conservation genomics of an exploited, popular aquarium trade species: the giant Caribbean sea anemone Condylactis gigantea (Anthozoa: Actiniidae)

Nancy E. Sheridan, Seifu Seyoum, William C. Sharp, Benjamin M. Titus, Marymegan Daly, Christina L. Richards & Aaron W. Schrey. 2023. Conservation Genetics 

Abstract

The marine aquarium trade in the United States operates primarily in Florida, and though the trade’s effects on many marine taxa are largely unknown, local declines have been observed for some harvested species. To reverse local declines in the abundance of the giant Caribbean sea anemone Condylactis gigantea, state managers prohibited harvest of this popular aquarium organism in late 2012. To assess the recovery of C. gigantea following the moratorium, we monitored relative abundance at 45 fixed locations in South Florida from 2013 to 2016. Seventeen of the sites were locations provided to us by commercial aquarium-trade collectors. The remaining sites were locations at which C. gigantea was presumably not being exploited. We found increased densities at only 4 of those 17 sites, while densities at the remaining sites remained unchanged. We also examined genome-wide single nucleotide polymorphism data to assess genetic diversity and population structure of 82 individuals from seven locations (three collection and four non-collection locations) across South Florida. Observed genetic diversity was comparable in all locations. But the location in the eastern Gulf of Mexico showed a significant FIS value, suggesting inbreeding that might be attributed to a small number of occupants. Condylactis gigantea is generally well mixed across South Florida, though a relatively weak pattern of genetic differentiation was detected. These results suggest limited reproductive success and dispersal that is restricted by hydrological and geographical barriers. We highlight the importance of periodic population and genetic monitoring to assess changes in relative abundance and genetic diversity.

There and Back Again: The Unexpected Journeys of Metridium de Blainville, 1824 between the Old Oceans and throughout the Modern World

Heather Glon, Vreni Häussermann, Paul E. Brewin, Paul Brickle, Sungsik Kong, Megan L. Smith, and Marymegan Daly. The Biological Bulletin,Volume 244, Number 1

Abstract

Members of the sea anemone genus Metridium are abundant in temperate rocky habitats and fouling communities. Their biogeographic history is expected to reflect changes in currents and habitats that have influenced benthic communities, such as the climate-influenced changes that occurred during the Last Glacial Maximum. More recently, however, anthropogenic influences such as shipping transportation and the creation of artificial habitat have altered and affected the composition of modern-day marine communities. Here we use sequence-capture data to examine the genetic structure of Metridium across its shallow-water distribution to (1) evaluate species boundaries within Metridium, (2) elucidate the dispersal history of Metridium between and among oceans, and (3) assess the influence of anthropogenic movement on modern-day populations. We find strong evidence for two species within Metridium: M. farcimen and M. senile. Dispersal from the Pacific to the Atlantic included a subsequent isolation of a small population in or above the Bering Sea, which has presumably moved southward. Within the native range of M. senile, admixture is prevalent even between oceans as a result of anthropogenic activities. The nonnative populations in Chile and the Falkland Islands came from at least two distinct introduction events originating from both coasts of the United States in the North Pacific and North Atlantic Oceans. Hybridization between M. senile and M. farcimen is documented as occurring in anthropogenically influenced habitats. The heavy influence from anthropogenic activities will continue to impact our understanding of marine organisms, particularly within the native range and for those that are easily transported across long distances.

Greater flowering and response to flooding in Lythrum virgatum than L. salicaria (purple loosestrife)

Kali Z. Mattingly1, Brenna N. Braasch, Stephen M. Hovick. 2023. AoB PLANTS, plad009, https://doi.org/10.1093/aobpla/plad009

Abstract

Newly introduced trait diversity can spur rapid evolution and facilitate local adaptation in the introduced plant Lythrum salicaria. The horticultural plant L. virgatum might further introduce meaningful trait variation by escaping into established L. salicaria populations or by hybridizing with L. salicaria. Although many experiments have focused on L. salicaria genotypes, relatively little is known about L. virgatum ecology. We used a greenhouse common garden to compare traits and flood response of L. salicaria and L. virgatum collected from two sources each in their native range. We tested the hypotheses that these two wetland taxa have comparable responses to flooding (inundation), and that flood tolerance correlated to higher fitness. Flooding produced stronger stress responses in L. virgatum. Compared to L. salicaria, L. virgatum shifted more aboveground allocation away from reproduction, decreased inflorescence biomass by 40% more, and produced 7% more stem aerenchymatous phellum, a specialized tissue that maintains aeration. Despite these more pronounced responses to flooding stress, L. virgatum had higher fitness (inflorescence Accepted Manuscript biomass and reproductive allocation) than L. salicaria. Overall, L. virgatum differed from L. salicaria in functionally important ways. Lythrum virgatum persisted under flooding and produced more reproductive biomass than L. salicaria under both flooded and non-flooded conditions. However, inundation stressed L. virgatum more than L. salicaria. Lythrum virgatum is likely able to establish into the wetland habitats in which L. salicaria prevails but may possess broader habitat tolerances.

A global test of hybrid ancestry from genome-scale data

Md Rejuan Haque* and Laura Kubatko. De Gruyter Journal 2023. doi: https://doi.org/10.1101/2023.02.24.529943

Abstract

Methods based on the multi-species coalescence have been widely used in phylogenetic tree estimation using genome-scale DNA sequence data to understand the underlying evolutionary relationship between the sampled species. Evolutionary processes such as hybridization, which creates new species through interbreeding between two different species, necessitate inferring a species network instead of a species tree. A species tree is strictly bifurcating and thus fails to incorporate hybridization events which require an internal node of degree three. Hence, it is crucial to decide whether a tree or network analysis should be performed given a DNA sequence data set, a decision that is based on the presence of hybrid species in the sampled species. Although many methods have been proposed for hybridization detection, it is rare to find a technique that does so globally while considering a data generation mechanism that allows both hybridization and incomplete lineage sorting. In this paper, we consider hybridization and coalescence in a unified framework and propose a new test that can detect whether there are any hybrid species in a given set of species. We propose that based on this global test of hybridization, one can decide whether a tree or network analysis is appropriate for a given data set.