Sven Olof Ulefors

Bio: Sven Olof Ulefors is an academic researcher. The author has contributed to research in topics: Monophyly & Genus. The author has an hindex of 2, co-authored 2 publications receiving 11 citations.

A new species group in Megaselia, the lucifrons group, with description of a new species (Diptera, Phoridae)

Abstract: With 1,400 described species, Megaselia is one of the most species-rich genera in the animal kingdom, and at the same time one of the least studied. An important obstacle to taxonomic progress is the lack of knowledge concerning the phylogenetic structure within the genus. Classification of Megaselia at the level of subgenus is incomplete although Schmitz addressed several groups of species in a series of monographs published from 1956 to 1981. Another problem is the lack of molecular phylogenetic analyses to support morphology-based conclusions. As a contribution towards addressing these problems, we here circumscribe a previously unrecognized monophyletic lineage of Megaselia consisting of species similar to Megaselialucifrons. We base this taxonomic decision on morphological study of an extensive phorid material from Sweden, complemented by molecular analyses of select exemplars using two markers (COI and 28S). We name the clade the lucifrons species group, and show that it contains three distinct species. Our results also demonstrate that Megaseliasubnitida Lundbeck, 1920, previously treated as a synonym of Megaselialucifrons Schmitz, 1918, is a separate species, and we remove it from synonymy. The third species in the group was previously unknown; we describe it here as Megaseliaalbalucifrons sp. n.

Scuttling towards monophyly: phylogeny of the mega‐diverse genus Megaselia (Diptera: Phoridae)

Abstract: The genus Megaselia Rondani (Diptera: Phoridae) is one of the largest in the animal kingdom, with nearly 1700 described species and many remaining to be discovered. Work on this group is notoriously challenging due to the extreme species diversity, poor knowledge of higher‐level relationships and lack of molecular data. In this paper, we present the largest study to date of Megaselia relationships based on molecular data from one nuclear (28S rDNA) and three mitochondrial (ND1, COI and 16S) markers for 175 Nordic specimens representing 145 species of Megaselia, plus outgroups. Based on phylogenetic analyses of these data, we propose 22 informal Megaselia species groups, all of which match well‐supported terminal clades. Relationships among these groups, and between them and several isolated species, remain largely uncertain. Of the 22, 20 species groups fall into a moderately well‐supported monophyletic clade of ‘core Megaselia’. Two species groups, the spinigera and ruficornis groups, fall outside of core Megaselia, as does the single representative of Myriophora, a genus that is included in Megaselia by some specialists. Here, we explore the morphology of these molecular species groups to aid future studies, and we discuss the implications of our findings for the generic circumscription of Megaselia. Hopefully, our results can aid further characterization of subgroups within the enormous Megaselia radiation and among its closest relatives, thus facilitating future work on this challenging but fascinating group of small flies.

FLIES - The Natural History and Diversity of Diptera

Abstract: Human knowledge will be erased from the world’s archives before we possess the last word that a gnat has to say to us. -Henri Fabre- The new book, FLIES, tells us a lot about what gnats and their relatives have to tell us about nature, would we but listen attentively. The author, Stephen Marshall, began his biological interests in beetles and then somehow went to the dark side, FLIES. This reviewer began his career in beetles and stayed put; that is what qualifies him as a reviewer of this simply superb book Steve Marshall has produced both in text and images. Why? It’s in the subtitle: the Natural History and Diversity of Diptera, the key word being diversity by which Marshall means many different kinds. Beetles and parasitic wasps are universally touted as the hyper-diverse and divergent groups of insects, so why does Marshall claim that Flies also exhibit such diversity in the natural world? In doing so, he sets himself apart from what more focused Dipterists have usually done, that is stay the course, look at one genus, one family, one region at a time; not much diversity displayed on their watch, for sure. Marshall, on the other hand, took on the entire dipteran Order, globally, with hundreds of superb photos (adults and immatures) that he took in the field over years of searching out fly species richness. He added an up-to-date text covering all taxa of the entire Order at the subfamily and tribal levels with hundreds of examples and images named at the genus and/or species level. Marshall’s FLIES is written and imaged for both the academic and the enthusiastic layperson. It contains some 2000 color images of flies in their natural environment, nearly all taken by the author. He has selected (out of some 160,000 named species of flies), those that he finds especially fascinating and those essential for demonstrating global dipteran diversity in form and function. The latter, form and function, speak directly to the astounding diversity and divergence of dipterans and justify including them along with the celebrated richness and abundance of beetles and parasitic wasps. Marshall, in FLIES, has justified that leap with his broad coverage and excellent story telling about flies’ lives. Such dipteran diversity is a mixed blessing for the public and for scientists alike. Who wants to see a blow fly from your neighbor’s garbage bin walking around on your chocolate cake, or a dozen mosquitos landing on you when you are trying patiently to photograph a hummingbird at a tropical flower in an Amazonian Heliconia patch? On the other hand, colorful hover flies on a yellow flower (Marshall’s book cover jacket) are part of nature’s exquisite beauty. While many groups of flies are vectors of devastating human and animal diseases and pests of crops and forests, others are important pollinators, recyclers, and beneficial control agents of insect pests. Marshall’s text tells compelling stories about all these kinds of flies that are easily read by citizen naturalists and high-schoolers in science class, as well as professional biologists of all walks of study. While Marshall’s introduction claims that “flies rule!” and his book sets out to prove that claim, Coleopterists and Hymenopterists certainly will argue that point. However, this reviewer has to agree that in the Amazon Basin during the rainy season there is more fly abundance by far in the rain forest canopy than any other group of insects (except relatively species-poor but abundant ants). This is thanks to one family of dipterans, the fungus gnats, Mycetophilidae (see Marshall’s pages 139-140) that emerge by the multimillions, as fungi reach their fruiting peak. While flies might not truly “rule,” gnats do have a lot to say about temperate and tropical fly abundance, something that Henri Fabre would appreciate. Without a doubt, Marshall sets high standards with this and his previous book, Insects: Their Natural History and Diversity, (also, Firefly Books). These treatments offer a challenge to entomologists of other ordinal taxa to produce similar books. Should that come to pass, and considering that insect and their relatives constitute three-fourths of life on earth, we humans would have a far better understanding of the natural world and our place in it.

Comprehensive inventory of true flies (Diptera) at a tropical site

Abstract: Estimations of tropical insect diversity generally suffer from lack of known groups or faunas against which extrapolations can be made, and have seriously underestimated the diversity of some taxa. Here we report the intensive inventory of a four-hectare tropical cloud forest in Costa Rica for one year, which yielded 4332 species of Diptera, providing the first verifiable basis for diversity of a major group of insects at a single site in the tropics. In total 73 families were present, all of which were studied to the species level, providing potentially complete coverage of all families of the order likely to be present at the site. Even so, extrapolations based on our data indicate that with further sampling, the actual total for the site could be closer to 8000 species. Efforts to completely sample a site, although resource-intensive and time-consuming, are needed to better ground estimations of world biodiversity based on limited sampling.

Completing Linnaeus’s inventory of the Swedish insect fauna: Only 5,000 species left?

Abstract: Despite more than 250 years of taxonomic research, we still have only a vague idea about the true size and composition of the faunas and floras of the planet. Many biodiversity inventories provide limited insight because they focus on a small taxonomic subsample or a tiny geographic area. Here, we report on the size and composition of the Swedish insect fauna, thought to represent roughly half of the diversity of multicellular life in one of the largest European countries. Our results are based on more than a decade of data from the Swedish Taxonomy Initiative and its massive inventory of the country's insect fauna, the Swedish Malaise Trap Project The fauna is considered one of the best known in the world, but the initiative has nevertheless revealed a surprising amount of hidden diversity: more than 3,000 new species (301 new to science) have been documented so far. Here, we use three independent methods to analyze the true size and composition of the fauna at the family or subfamily level: (1) assessments by experts who have been working on the most poorly known groups in the fauna; (2) estimates based on the proportion of new species discovered in the Malaise trap inventory; and (3) extrapolations based on species abundance and incidence data from the inventory. For the last method, we develop a new estimator, the combined non-parametric estimator, which we show is less sensitive to poor coverage of the species pool than other popular estimators. The three methods converge on similar estimates of the size and composition of the fauna, suggesting that it comprises around 33,000 species. Of those, 8,600 (26%) were unknown at the start of the inventory and 5,000 (15%) still await discovery. We analyze the taxonomic and ecological composition of the estimated fauna, and show that most of the new species belong to Hymenoptera and Diptera groups that are decomposers or parasitoids. Thus, current knowledge of the Swedish insect fauna is strongly biased taxonomically and ecologically, and we show that similar but even stronger biases have distorted our understanding of the fauna in the past. We analyze latitudinal gradients in the size and composition of known European insect faunas and show that several of the patterns contradict the Swedish data, presumably due to similar knowledge biases. Addressing these biases is critical in understanding insect biomes and the ecosystem services they provide. Our results emphasize the need to broaden the taxonomic scope of current insect monitoring efforts, a task that is all the more urgent as recent studies indicate a possible worldwide decline in insect faunas.

Large-scale Integrative Taxonomy (LIT): resolving the data conundrum for dark taxa

Abstract: New, rapid, accurate, scalable, and cost-effective species discovery and delimitation methods are needed for tackling "dark taxa", that we here define as clades for which <10% of all species are described and the estimated diversity exceeds 1000 species. Species delimitation should be based on multiple data sources ("integrative taxonomy") but collecting several types of data for the same specimens risks impeding the discovery process that is already too slow. We here show how this can be avoided with Large-scale Integrative Taxonomy (LIT). Preliminary species hypotheses are generated based on inexpensive data that are obtained quickly and cost-effectively in a technical exercise. The validation step is then based on a more expensive type of data that are only obtained for few specimens selected based on objective criteria. We here use this approach to sort 18 000 scuttle flies (Diptera: Phoridae) from Sweden into 315 preliminary species hypotheses based on NGS barcode (313bp) clusters. These clusters went through subsequent validation based on morphology and were then used to develop quantitative indicators for predicting which barcode clusters are in conflict with morphospecies. For this purpose, we first randomly selected 100 clusters for in-depth validation with morphology. Afterwards, we used a linear model to demonstrate that the best predictors for conflict between barcode clusters and morphology are maximum p-distance within the cluster and cluster stability across different clustering thresholds. A test of these indicators using the 215 remaining clusters reveals that these predictors correctly identify all clusters that conflict with morphology. The morphological validation step in our study involved just 1 039 specimens (5.8% of all specimens), but a newly proposed simplified protocol would only require the study of 915 (5.1%: 2.5 specimens per species) as we show that clusters without signatures of incongruence can be validated by only studying two specimens representing the most divergent haplotypes. To test the generality of our results across different barcode clustering techniques, we establish that the levels of conflict are similar across Objective Clustering (OC), Automatic Barcode Gap Discovery (ABGD), Poisson Tree Processes (PTP) and Refined Single Linkage (RESL) (used by Barcode of Life Data System (BOLD) to assign Barcode Index Numbers (BINs)). OC and ABGD achieved a maximum match score with morphology of 89% while PTP was slightly less effective (84%). RESL could only be tested for a subset of the specimens because the algorithm is not public. BINs based on 277 of the original 1 714 haplotypes were 86% congruent with morphology while the values were 89% for OC, 74% for PTP, and 72% for ABGD.

Completing Linneaus's inventory of the Swedish insect fauna: only 5,000 species left?

Abstract: Despite more than 250 years of taxonomic research, we still have only a vague idea about the true size and composition of the faunas and floras of the planet. Many biodiversity inventories provide limited insight because they focus on a small taxonomic subsample or a tiny geographic area. Here, we report on the size and composition of the Swedish insect fauna, thought to represent roughly half of the diversity of multicellular life in one of the largest European countries. Our results are based on more than a decade of data from the Swedish Taxonomy Initiative and its massive inventory of the country9s insect fauna, the Swedish Malaise Trap Project The fauna is considered one of the best known in the world, but the initiative has nevertheless revealed a surprising amount of hidden diversity: more than 3,000 new species (301 new to science) have been documented so far. Here, we use three independent methods to analyze the true size and composition of the fauna at the family or subfamily level: (1) assessments by experts who have been working on the most poorly known groups in the fauna; (2) estimates based on the proportion of new species discovered in the Malaise trap inventory; and (3) extrapolations based on species abundance and incidence data from the inventory. For the last method, we develop a new estimator, the combined non-parametric estimator, which we show is less sensitive to poor coverage of the species pool than other popular estimators. The three methods converge on similar estimates of the size and composition of the fauna, suggesting that it comprises around 33,000 species. Of those, 8,600 (26%) were unknown at the start of the inventory and 5,000 (15%) still await discovery. We analyze the taxonomic and ecological composition of the estimated fauna, and show that most of the new species belong to Hymenoptera and Diptera groups that are decomposers or parasitoids. Thus, current knowledge of the Swedish insect fauna is strongly biased taxonomically and ecologically, and we show that similar but even stronger biases have distorted our understanding of the fauna in the past. We analyze latitudinal gradients in the size and composition of known European insect faunas and show that several of the patterns contradict the Swedish data, presumably due to similar knowledge biases. Addressing these biases is critical in understanding insect biomes and the ecosystem services they provide. Our results emphasize the need to broaden the taxonomic scope of current insect monitoring efforts, a task that is all the more urgent as recent studies indicate a possible worldwide decline in insect faunas.