scholarly journals Population-specific patterns of toxin sequestration in monarch butterflies from around the world

2021 ◽  
Author(s):  
Micah Freedman ◽  
Sue-Ling Choquette ◽  
Santiago Ramirez ◽  
Sharon Strauss ◽  
Mark Hunter ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Species Interactions ◽  
Evolutionary History ◽  
Host Plants ◽  
Strong Support ◽  
Population Level ◽  
Oceanic Island ◽  
Asclepias Syriaca ◽  
Monarch Butterflies ◽  
Toxin Sequestration

Monarch butterflies are one of the preeminent examples of a toxin-sequestering animal, gaining protection against predators via cardenolides obtained from their milkweed host plants. Although cardenolide sequestration by monarchs has been studied in ecological, physiological, and phylogenetic contexts, relatively little research has surveyed genetic variation in the ability to sequester, nor has monarch sequestration been studied in relation to divergent host plant assemblages or variation in exposure to predation. Here, we use the monarch's recent global range expansion to test hypotheses about how cardenolide sequestration evolves over relatively contemporary time scales. First, we test for whether sympatric monarch/milkweed combinations have a sequestration advantage by rearing six geographically disparate monarch populations on six associated milkweed host species and measuring levels of sequestered cardenolides in a set of 440 adult butterflies. Second, we use monarchs from Guam - an oceanic island where birds have been functionally extirpated for approximately 40 years - to test hypotheses about how exposure to avian predation affects cardenolide sequestration. We find little overall evidence for increased sequestration on sympatric hosts. However, one monarch population (Puerto Rico) shows strong support for cross-host tradeoffs in sequestration ability, primarily driven by limited sequestration of polar cardenolides from two temperate North American milkweeds (Asclepias syriaca and A. speciosa). Monarchs from Guam show some evidence for reduced cardenolide sequestration in both a cross-island comparison of wild-caught butterflies as well as population-level comparisons of greenhouse-reared butterflies. Our results suggest that there is substantial genetic variation in sequestration ability (both within and between monarch populations) and that evolutionary history and contemporary species interactions may influence patterns of cardenolide sequestration.

scholarly journals Understanding UCEs: A Comprehensive Primer on Using Ultraconserved Elements for Arthropod Phylogenomics

2019 ◽  
Vol 3 (5) ◽  
Author(s):  
Y Miles Zhang ◽  
Jason L Williams ◽  
Andrea Lucky
Keyword(s):  
Time Scales ◽  
Evolutionary History ◽  
Population Level ◽  
Tree Of Life ◽  
Deep Time ◽  
Ultraconserved Elements ◽  
Background Theory ◽  
Promising Tool ◽  
Recent Advances ◽  
Targeted Enrichment

Abstract Targeted enrichment of ultraconserved elements (UCEs) has emerged as a promising tool for inferring evolutionary history in many taxa, with utility ranging from phylogenetic and biogeographic questions at deep time scales to population level studies at shallow time scales. However, the methodology can be daunting for beginners. Our goal is to introduce UCE phylogenomics to a wider audience by summarizing recent advances in arthropod research, and to familiarize readers with background theory and steps involved. We define terminology used in association with the UCE approach, evaluate current laboratory and bioinformatic methods and limitations, and, finally, provide a roadmap of steps in the UCE pipeline to assist phylogeneticists in making informed decisions as they employ this powerful tool. By facilitating increased adoption of UCEs in phylogenomics studies that deepen our comprehension of the function of these markers across widely divergent taxa, we aim to ultimately improve understanding of the arthropod tree of life.

scholarly journals High differentiation in functional traits but similar phenotypic plasticity in populations of a soil specialist along a climatic gradient

2020 ◽  
Vol 125 (6) ◽  
pp. 969-980 ◽  
Author(s):  
Silvia Matesanz ◽  
Marina Ramos-Muñoz ◽  
Mario Blanco-Sánchez ◽  
Adrián Escudero
Keyword(s):  
Genetic Variation ◽  
Phenotypic Plasticity ◽  
Functional Traits ◽  
Common Garden ◽  
Population Level ◽  
General Purpose ◽  
Climatic Conditions ◽  
Environment Interaction ◽  
Moisture Variation ◽  
Neutral Genetic Variation

Abstract Background and Aims Plants experiencing contrasting environmental conditions may accommodate such heterogeneity by expressing phenotypic plasticity, evolving local adaptation or a combination of both. We investigated patterns of genetic differentiation and plasticity in response to drought in populations of the gypsum specialist Lepidium subulatum. Methods We created an outdoor common garden with rain exclusion structures using 60 maternal progenies from four distinct populations that substantially differ in climatic conditions. We characterized fitness, life history and functional plasticity in response to two contrasting treatments that realistically reflect soil moisture variation in gypsum habitats. We also assessed neutral genetic variation and population structure using microsatellite markers. Key Results In response to water stress, plants from all populations flowered earlier, increased allocation to root tissues and advanced leaf senescence, consistent with a drought escape strategy. Remarkably, these probably adaptive responses were common to all populations, as shown by the lack of population × environment interaction for almost all functional traits. This generally common pattern of response was consistent with substantial neutral genetic variation and large differences in population trait means. However, such population-level trait variation was not related to climatic conditions at the sites of origin. Conclusions Our results show that, rather than ecotypes specialized to local climatic conditions, these populations are composed of highly plastic, general-purpose genotypes in relation to climatic heterogeneity. The strikingly similar patterns of plasticity among populations, despite substantial site of origin differences in climate, suggest past selection on a common norm of reaction due to similarly high levels of variation within sites. It is thus likely that plasticity will have a prevalent role in the response of this soil specialist to further environmental change.

scholarly journals How diverse can rare species be on the margins of genera distribution?

AoB Plants ◽  
2019 ◽  
Vol 11 (4) ◽  
Author(s):  
Alice Backes ◽  
Geraldo Mäder ◽  
Caroline Turchetto ◽  
Ana Lúcia Segatto ◽  
Jeferson N Fregonezi ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Genetic Variation ◽  
Genetic Variability ◽  
Habitat Loss ◽  
Evolutionary History ◽  
Founder Effects ◽  
Geographical Isolation ◽  
Genetic Diversity And Structure ◽  
Genetic Patterns

Abstract Different genetic patterns have been demonstrated for narrowly distributed taxa, many of them linking rarity to evolutionary history. Quite a few species in young genera are endemics and have several populations that present low variability, sometimes attributed to geographical isolation or dispersion processes. Assessing the genetic diversity and structure of such species may be important for protecting them and understanding their diversification history. In this study, we used microsatellite markers and plastid sequences to characterize the levels of genetic variation and population structure of two endemic and restricted species that grow in isolated areas on the margin of the distribution of their respective genera. Plastid and nuclear diversities were very low and weakly structured in their populations. Evolutionary scenarios for both species are compatible with open-field expansions during the Pleistocene interglacial periods and genetic variability supports founder effects to explain diversification. At present, both species are suffering from habitat loss and changes in the environment can lead these species towards extinction.

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