Changing climates can influence species range shifts and biological invasions, but the mechanisms are not fully known. Using the model species
The rapid invasion of the non‐native
- NSF-PAR ID:
- 10363942
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Molecular Ecology
- Volume:
- 31
- Issue:
- 4
- ISSN:
- 0962-1083
- Page Range / eLocation ID:
- p. 1142-1159
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Phragmites australis (Cav.) Trin. ex Steud. (Poaceae ), we conducted a global analysis of climate and plant native and introduced cytotypes to determine whether this relationship influences population distributions, hypothesizing that smaller genomes are more common in regions of greater environmental stress. First, we identified 598Phragmites australis field-collected native and introduced genome size variants using flow cytometry. We then evaluated whether temperature and precipitation were associated withP. australis monoploid genome size (Cx-value) distributions using Cx-value and Worldclim data. After accounting for potential spatial autocorrelation among source populations, we found climate significantly influenced Cx-value prevalence on continents. The relationships of Cx-value to temperature and precipitation varied according to whether plants were native or introduced in North America and Europe, and Cx-values were strongly influenced by precipitation during the dry season. Smaller plant monoploid genome size was associated with more stressful abiotic conditions; under extreme high temperatures and under drought, plants had smaller Cx-values. This may influence genome dominance, biological invasions, and range expansions and contractions as climate change selects for genome sizes that maximize fitness. -
PREMISE Biological invasions increasingly threaten native biodiversity and ecosystem services. One notable example is the common reed,
Phragmites australis , which aggressively invades North American salt marshes. Elevated atmospheric CO2and nitrogen pollution enhance its growth and facilitate invasion becauseP. australis responds more strongly to these enrichments than do native species. We investigated how modifications to stomatal features contribute to strong photosynthetic responses to CO2and nitrogen enrichment inP. australis by evaluating stomatal shifts under experimental conditions and relating them to maximal stomatal conductance (g wmax) and photosynthetic rates.METHODS Plants were grown
in situ in open‐top chambers under ambient and elevated atmospheric CO2(eCO2) and porewater nitrogen (Nenr) in a Chesapeake Bay tidal marsh. We measured light‐saturated carbon assimilation rates (A sat) and stomatal characteristics, from which we calculatedg wmaxand determined whether CO2and Nenraltered the relationship betweeng wmaxandA sat.RESULTS eCO2and Nenrenhanced both
g wmaxandA sat, but to differing degrees;g wmaxwas more strongly influenced by Nenrthrough increases in stomatal density whileA satwas more strongly stimulated by eCO2. There was a positive relationship betweeng wmaxandA satthat was not modified by eCO2or Nenr, individually or in combination.CONCLUSIONS Changes in stomatal features co‐occur with previously described responses of
P. australis to eCO2and Nenr. Complementary responses of stomatal length and density to these global change factors may facilitate greater stomatal conductance and carbon gain, contributing to the invasiveness of the introduced lineage. -
Abstract Leafhoppers comprise over 20,000 plant‐sap feeding species, many of which are important agricultural pests. Most species rely on two ancestral bacterial symbionts,
Sulcia andNasuia , for essential nutrition lacking in their phloem and xylem plant sap diets. To understand how pest leafhopper genomes evolve and are shaped by microbial symbioses, we completed a chromosomal‐level assembly of the aster leafhopper's genome (ALF;Macrosteles quadrilineatus ). We compared ALF's genome to three other pest leafhoppers,Nephotettix cincticeps ,Homalodisca vitripennis , andEmpoasca onukii , which have distinct ecologies and symbiotic relationships. Despite diverging ~155 million years ago, leafhoppers have high levels of chromosomal synteny and gene family conservation. Conserved genes include those involved in plant chemical detoxification, resistance to various insecticides, and defence against environmental stress. Positive selection acting upon these genes further points to ongoing adaptive evolution in response to agricultural environments. In relation to leafhoppers' general dependence on symbionts, species that retain the ancestral symbiont,Sulcia , displayed gene enrichment of metabolic processes in their genomes. Leafhoppers with bothSulcia and its ancient partner,Nasuia , showed genomic enrichment in genes related to microbial population regulation and immune responses. Finally, horizontally transferred genes (HTGs) associated with symbiont support ofSulcia andNasuia are only observed in leafhoppers that maintain symbionts. In contrast, HTGs involved in non‐symbiotic functions are conserved across all species. The high‐quality ALF genome provides deep insights into how host ecology and symbioses shape genome evolution and a wealth of genetic resources for pest control targets. -
Abstract Islands are natural laboratories for studying patterns and processes of evolution. Research on island endemic birds has revealed elevated speciation rates and rapid phenotypic evolution in several groups (e.g. white-eyes, Darwin’s finches). However, understanding the evolutionary processes behind these patterns requires an understanding of how genotypes map to novel phenotypes. To date, there are few high-quality reference genomes for species found on islands. Here, we sequence the genome of one of Ernst Mayr’s “great speciators,” the collared kingfisher (Todiramphus chloris collaris). Utilizing high molecular weight DNA and linked-read sequencing technology, we assembled a draft high-quality genome with highly contiguous scaffolds (scaffold N50 = 19 Mb). Based on universal single-copy orthologs, we estimated a gene space completeness of 96.6% for the draft genome assembly. The population demographic history analyses reveal a distinct pattern of contraction and expansion in population size throughout the Pleistocene. Comparative genomic analysis of gene family evolution revealed that species-specific and rapidly expanding gene families in the collared kingfisher (relative to other Coraciiformes) are mainly involved in the ErbB signaling pathway and focal adhesion. Todiramphus kingfishers are a species-rich group that has become a focus of speciation research. This draft genome will be a platform for future taxonomic, phylogeographic, and speciation research in the group. For example, target genes will enable testing of changes in sensory structures associated with changes in vision and taste genes across kingfishers.
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