| 1. |
- Li, You, et al.
(författare)
-
Preinvasion Assessment of Exotic Bark Beetle-Vectored Fungi to Detect Tree-Killing Pathogens
- 2022
-
Ingår i: Phytopathology. - 0031-949X. ; 112:2, s. 261-270
-
Tidskriftsartikel (refereegranskat)abstract
- Exotic diseases and pests of trees have caused continental-scale disturbances in forest ecosystems and industries, and their invasions are considered largely unpredictable. We tested the concept of preinvasion assessment of not yet invasive organisms, which enables empirical risk assessment of potential invasion and impact. Our example assesses fungi associated with Old World bark and ambrosia beetles and their potential to impact North American trees. We selected 55 Asian and European scolytine beetle species using host use, economic, and regulatory criteria. We isolated 111 of their most consistent fungal associates and tested their effect on four important southeastern American pine and oak species. Our test dataset found no highly virulent pathogens that should be classified as an imminent threat. Twenty-two fungal species were minor pathogens, which may require context-dependent response for their vectors at North American borders, while most of the tested fungi displayed no significant impact. Our results are significant in three ways; they ease the concerns over multiple overseas fungus vectors suspected of heightened potential risk, they provide a basis for the focus on the prevention of introduction and establishment of species that may be of consequence, and they demonstrate that preinvasion assessment, if scaled up, can support practical risk assessment of exotic pathogens.
|
|
| 2. |
- Neves, Jessika M.M., et al.
(författare)
-
Genomic methods reveal independent demographic histories despite strong morphological conservatism in fish species
- 2021
-
Ingår i: Heredity. - : Springer Science and Business Media LLC. - 0018-067X .- 1365-2540. ; 127:3, s. 323-333
-
Tidskriftsartikel (refereegranskat)abstract
- Human overexploitation of natural resources has placed conservation and management as one of the most pressing challenges in modern societies, especially in regards to highly vulnerable marine ecosystems. In this context, cryptic species are particularly challenging to conserve because they are hard to distinguish based on morphology alone, and thus it is often unclear how many species coexist in sympatry, what are their phylogenetic relationships and their demographic history. We answer these questions using morphologically similar species of the genus Mugil that are sympatric in the largest coastal Marine Protected Area in the Tropical Southwestern Atlantic marine province. Using a sub-representation of the genome, we show that individuals are assigned to five highly differentiated genetic clusters that are coincident with five mitochondrial lineages, but discordant with morphological information, supporting the existence of five species with conserved morphology in this region. A lack of admixed individuals is consistent with strong genetic isolation between sympatric species, but the most likely species tree suggests that in one case speciation has occurred in the presence of interspecific gene flow. Patterns of genetic diversity within species suggest that effective population sizes differ up to two-fold, probably reflecting differences in the magnitude of population expansions since species formation. Together, our results show that strong morphologic conservatism in marine environments can lead to species that are difficult to distinguish morphologically but that are characterized by an independent evolutionary history, and thus that deserve species-specific management strategies.
|
|
| 3. |
- Nolen, Zachary J, et al.
(författare)
-
Historical isolation facilitates species radiation by sexual selection : Insights from Chorthippus grasshoppers
- 2020
-
Ingår i: Molecular Ecology. - : WILEY. - 0962-1083 .- 1365-294X. ; 29:24, s. 4985-5002
-
Tidskriftsartikel (refereegranskat)abstract
- Theoretical and empirical studies have shown that species radiations are facilitated when a trait under divergent natural selection is also involved in sexual selection. It is yet unclear how quick and effective radiations are where assortative mating is unrelated to the ecological environment and primarily results from sexual selection. We address this question using sympatric grasshopper species of the genus Chorthippus, which have evolved strong behavioural isolation while lacking noticeable ecomorphological divergence. Mitochondrial genomes suggest that the radiation is relatively recent, dating to the mid-Pleistocene, which leads to extensive incomplete lineage sorting throughout the mitochondrial and nuclear genomes. Nuclear data shows that hybrids are absent in sympatric localities but that all species have experienced gene flow, confirming that reproductive isolation is strong but remains incomplete. Demographic modelling is most consistent with a long period of geographic isolation, followed by secondary contact and extensive introgression. Such initial periods of geographic isolation might facilitate the association between male signaling and female preference, permitting the coexistence of sympatric species that are genetically, morphologically, and ecologically similar, but otherwise behave mostly as good biological species.
|
|
| 4. |
- Boman, Jesper, et al.
(författare)
-
On the origin of an insular hybrid butterfly species
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Most species arise from the divergence of two populations within a species, but this is not only way speciation can occur. A new species can also evolve when diverging lineages hybridize and give rise to a persistent and ecologically differentiated species. Hybrid speciation in animals has been intensely debated, partly because hard evidence for the process have been difficult to gain. Recent access to large-scale, whole-genome sequencing data and development of novel analytical methods have made it more feasible to statistically test for hybrid origin of lineages. Here we report the discovery of a hybrid butterfly lineage. This lineage is mainly inhabiting an island in the Baltic Sea in Northern Europe and was previously described as a subspecies (horkei) of one of the parental species (Aricia artaxerxes). By analyzing whole-genome resequencing data, we conclude that horkei originated as a consequence of hybridization between A. artaxerxes and A. agestis. We show that this hybridization event occurred approximately 54,000 years ago, predating the last glaciation of the current distribution range. Horkei must therefore have persisted long enough to be able to colonize its current distribution range, despite that this range lies between the current ranges of the parental species. The hybrid origin, the maintenance of genomic integrity through time periods with dramatic climatic changes and the expression of a combination of parental traits - such as voltinism and host plant use - suggest that horkei can be considered a distinct species (Aricia horkei stat. nov.). Thus, we add to a growing list of hybrid speciation cases in animals.
|
|
| 5. |
- Nolen, Zachary J., et al.
(författare)
-
Species-specific erosion of genetic diversity in grassland butterflies depends on landscape land cover
- 2024
-
Ingår i: Biological Conservation. - 0006-3207. ; 296
-
Tidskriftsartikel (refereegranskat)abstract
- Changes in land cover, particularly agricultural intensification, are a primary cause of pollinator decline. Decline and isolation can reduce genetic diversity, reducing adaptive potential and unmasking genetic load. Maintenance of functional connectivity in changing landscapes is necessary to ensure persistence, but how land cover impacts genetic diversity and functional connectivity in butterflies remains poorly understood. We assess to which extent land cover functionally isolates grassland butterfly populations and what consequences isolation has for genetic diversity using whole genome and land cover data. We assess species-specific patterns across three butterfly species that vary in habitat specialization and mobility - Polyommatus icarus, Plebejus argus and Cyaniris semiargus - using samples from 6 to 11 populations across a ~25,000 km2 area in southern Sweden. We find that while generalist Po. icarus is nearly panmictic and heathland specialist Pl. argus maintains modest functional connectivity, grassland specialist C. semiargus exists in largely isolated populations. Genetic diversity in all species is positively related to grassland extent in the surrounding landscape. Arable and forest extent are positively and negatively related to genetic diversity in Po. icarus, while the inverse is true in C. semiargus. Lower functional connectivity in C. semiargus is coupled with higher rates of inbreeding, suggesting more urgent need of conservation action aimed at restoring functional connectivity in this species, illustrating how genetic data can reveal threats that may go unnoticed with abundance data alone. We conclude that specialist butterfly genetic diversity relies upon preservation of well-connected semi-natural grasslands to maintain functional connectivity at longer distances.
|
|
