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Search Results: 1 - 10 of 443 matches for " Niklas Wahlberg "
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Diversity begets diversity: host expansions and the diversification of plant-feeding insects
Niklas Janz, S?ren Nylin, Niklas Wahlberg
BMC Evolutionary Biology , 2006, DOI: 10.1186/1471-2148-6-4
Abstract: By applying a variant of independent contrast analysis, specially tailored for use on questions of species richness (MacroCAIC), we show that species richness is strongly correlated with diversity of host use in the butterfly family Nymphalidae. Furthermore, by comparing the results from reciprocal sister group selection, where sister groups were selected either on the basis of diversity of host use or species richness, we find that it is likely that diversity of host use is driving species richness, rather than vice versa.We conclude that resource diversity is correlated with species richness in the Nymphalidae and suggest a scenario based on recurring oscillations between host expansions – the incorporation of new plants into the repertoire – and specialization, as an important driving force behind the diversification of plant-feeding insects.The biodiversity crisis calls for a better understanding not only of the reasons for loss of diversity, but also for the processes that generate diversity. Plant-feeding insects are remarkably species-rich, making up at least one-quarter of all described species, so explaining the mechanisms behind the diversification of these groups will go a long way towards understanding global biodiversity [1,2]. The possible link between insect diversification and feeding on plants was made already by Ehrlich and Raven [3] in their seminal paper on the coevolution between butterflies and plants. Since then, it has been clearly demonstrated that herbivory has repeatedly led to rapid diversification of insects, but the mechanisms behind this diversification still remain uncertain [4,5]. Compared with alternative resources, plants are characterized by both high availability and high diversity. Insect diversification rates could conceivably be influenced by both resource abundance (decreased competition) and diversity (larger number of potential niches), but these hypotheses have so far not been tested with phylogenetic methods.It has become
Timing major conflict between mitochondrial and nuclear genes in species relationships of Polygonia butterflies (Nymphalidae: Nymphalini)
Niklas Wahlberg, Elisabet Weingartner, Andrew D Warren, S?ren Nylin
BMC Evolutionary Biology , 2009, DOI: 10.1186/1471-2148-9-92
Abstract: We investigate the species relationships and their evolutionary history over time in the genus Polygonia using DNA sequences from two mitochondrial gene regions (COI and ND1, total 1931 bp) and four nuclear gene regions (EF-1α, wingless, GAPDH and RpS5, total 2948 bp). We found clear, strongly supported conflict between mitochondrial and nuclear DNA sequences in estimating species relationships in the genus Polygonia. Nodes at which there was no conflict tended to have diverged at the same time when analyzed separately, while nodes at which conflict was present diverged at different times. We find that two species create most of the conflict, and attribute the conflict found in Polygonia satyrus to ancient hybridization and conflict found in Polygonia oreas to recent or ongoing hybridization. In both examples, the nuclear gene regions tended to give the phylogenetic relationships of the species supported by morphology and biology.Studies inferring species-level relationships using molecular data should never be based on a single locus. Here we show that the phylogenetic hypothesis generated using mitochondrial DNA gives a very different interpretation of the evolutionary history of Polygonia species compared to that generated from nuclear DNA. We show that possible cases of hybridization in Polygonia are not limited to sister species, but may be inferred further back in time. Furthermore, we provide more evidence that Haldane's effect might not be as strong a process in preventing hybridization in butterflies as has been previously thought.Phylogenetics at the species-level is becoming increasingly important in the study of processes underlying speciation [1,2]. Most species-level phylogenies have until recently been based on only mitochondrial DNA (mtDNA) due to the ease of PCR amplification and its perceived suitability, e.g. due to maternal inheritance (shorter time for coalescence than nuclear DNA (nDNA) because of smaller Ne), lack of recombination and relative
DNA barcoding and morphology reveal two common species in one: Pimpla molesta stat. rev. separated from P. croceipes (Hymenoptera, Ichneumonidae)
Anu Veijalainen,Gavin Broad,Niklas Wahlberg,John Longino
ZooKeys , 2011, DOI: 10.3897/zookeys.124.1780
Abstract: Correct species identification is the basis of ecological studies. Nevertheless, morphological examination alone may not be enough to tell species apart. Here, our integrated molecular and morphological studies demonstrate that the relatively widespread and common neotropical parasitoid wasp Pimpla croceipes Cresson, 1874 (Hymenoptera: Ichneumonidae: Pimplinae) actually consists of two distinct species. The name Pimpla molesta (Smith, 1879) stat. rev. is available for the second species. The two species were identified by DNA barcoding and minor differences in morphology and colouration. Our results support the previous notions that DNA barcoding can complement morphological identification and aid the discovery of cryptic species complexes.
Timing and Patterns in the Taxonomic Diversification of Lepidoptera (Butterflies and Moths)
Niklas Wahlberg, Christopher W. Wheat, Carlos Pe?a
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0080875
Abstract: The macroevolutionary history of the megadiverse insect order Lepidoptera remains little-known, yet coevolutionary dynamics with their angiospermous host plants are thought to have influenced their diversification significantly. We estimate the divergence times of all higher-level lineages of Lepidoptera, including most extant families. We find that the diversification of major lineages in Lepidoptera are approximately equal in age to the crown group of angiosperms and that there appear to have been three significant increases in diversification rates among Lepidoptera over evolutionary time: 1) at the origin of the crown group of Ditrysia about 150 million years ago (mya), 2) at the origin of the stem group of Apoditrysia about 120 mya and finally 3) a spectacular increase at the origin of the stem group of the quadrifid noctuoids about 70 mya. In addition, there appears to be a significant increase in diversification rate in multiple lineages around 90 mya, which is concordant with the radiation of angiosperms. Almost all extant families appear to have begun diversifying soon after the Cretaceous/Paleogene event 65.51 mya.
Next Generation Sequencing of Fecal DNA Reveals the Dietary Diversity of the Widespread Insectivorous Predator Daubenton’s Bat (Myotis daubentonii) in Southwestern Finland
Eero J. Vesterinen, Thomas Lilley, Veronika N. Laine, Niklas Wahlberg
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0082168
Abstract: Understanding predator-prey dynamics is a fundamental task in the evaluation of the adaptive capacities of species. However, direct observations or morphological identification of fecal remains do not offer an effective way to study the dietary ecology of elusive species, such as nocturnal insectivorous bats. However, recent advances in molecular techniques have opened a new method for identifying prey species from fecal samples. In this study, we amplified species-specific mitochondrial COI fragments from fecal DNA extractions from 34 individual Daubenton’s bats (Myotis daubentonii) collected between 2008 and 2010 from southwestern Finland. Altogether, 128 different species of prey were identified based on a comprehensive local DNA reference library. In our study area, Daubenton’s bats feed most frequently on insects of the orders Diptera (found in the diet of 94% individuals), Trichoptera (69%) and Lepidoptera (63%). The most frequent dipteran family in the diet was Chironomidae, which was found in 31 of 34 individuals. Most common prey species were chironomids Microtendipes pedellus (found in 50% of bats), Glyptotendipes cauliginellus (44%), and Procladius ferrugineus (41%). For the first time, an accurate species level list of the diet of the insectivorous Daubenton’s bat (Myotis daubentonii) in Finland is presented. We report a generally applicable method for describing the arthropod diet of vertebrate predators. We compare public databases to a national database to highlight the importance of a local reference database.
Mitochondrial DNA Signature for Range-Wide Populations of Bicyclus anynana Suggests a Rapid Expansion from Recent Refugia
Maaike A. de Jong, Niklas Wahlberg, Marleen van Eijk, Paul M. Brakefield, Bas J. Zwaan
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0021385
Abstract: This study investigates the genetic diversity, population structure and demographic history of the afrotropical butterfly Bicyclus anynana using mitochondrial DNA (mtDNA). Samples from six wild populations covering most of the species range from Uganda to South Africa were compared for the cytochrome c oxidase subunit gene (COI). Molecular diversity indices show overall high mtDNA diversity for the populations, but low nucleotide divergence between haplotypes. Our results indicate relatively little geographic population structure among the southern populations, especially given the extensive distributional range and an expectation of limited gene flow between populations. We implemented neutrality tests to assess signatures of recent historical demographic events. Tajima's D test and Fu's FS test both suggested recent population growth for the populations. The results were only significant for the southernmost populations when applying Tajima's D, but Fu's FS indicated significant deviations from neutrality for all populations except the one closest to the equator. Based on our own findings and those from pollen and vegetation studies, we hypothesize that the species range of B. anynana was reduced to equatorial refugia during the last glacial period, and that the species expanded southwards during the past 10.000 years. These results provide crucial background information for studies of phenotypic and molecular adaptation in wild populations of B. anynana.
Variation of Basal EROD Activities in Ten Passerine Bird Species – Relationships with Diet and Migration Status
Miia J. Rainio, Mirella Kanerva, Niklas Wahlberg, Mikko Nikinmaa, Tapio Eeva
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0033926
Abstract: Inter-specific differences in animal defence mechanisms against toxic substances are currently poorly understood. The ethoxyresorufin-O-deethylase (EROD) enzyme plays an important role in defence against toxic chemicals in a wide variety of animals, and it is an important biomarker for environmental contamination. We compared basal hepatic EROD activity levels among ten passerine species to see if there is inter-specific variation in enzyme activity, especially in relation to their diet and migration status. Migratory insectivores showed higher EROD activity compared to granivores. We hypothesize that the variable invertebrate diet of migratory insectivores contains a wider range of natural toxins than the narrower diet of granivores. This may have affected the evolution of mixed function oxidases (MFO) system and enzyme activities. We further tested whether metabolic rates or relative liver size were associated with the variation in detoxification capacity. We found no association between EROD activity and relative (per mass unit) basal metabolic rate (BMR). Instead, EROD activity and relative liver mass (% of body mass) correlated positively, suggesting that a proportionally large liver also functions efficiently. Our results suggest that granivores and non-migratory birds may be more vulnerable to environmental contaminants than insectivores and migratory birds. The diet and migration status, however, are phylogenetically strongly connected to each other, and their roles cannot be fully separated in our analysis with only ten passerine species.
Negative density-distribution relationship in butterflies
Jussi P?ivinen, Alessandro Grapputo, Veijo Kaitala, Atte Komonen, Janne S Kotiaho, Kimmo Saarinen, Niklas Wahlberg
BMC Biology , 2005, DOI: 10.1186/1741-7007-3-5
Abstract: We report a strong, but counterintuitive, negative relationship between density and distribution in the butterfly fauna of Finland. With an exceptionally comprehensive data set (data includes all 95 resident species in Finland and over 1.5 million individuals), we have been able to submit several of the mechanisms to powerful direct empirical testing. Without exception, we failed to find evidence for the proposed mechanisms creating a positive density-distribution relationship. On the contrary, we found that many of the mechanisms are equally able to generate a negative relationship.We suggest that one important determinant of density-distribution relationships is the geographical location of the study: on the edge of a distribution range, suitable habitat patches are likely to be more isolated than in the core of the range. In such a situation, only the largest and best quality patches are likely to be occupied, and these by definition can support a relatively dense population leading to a negative density-distribution relationship. Finally, we conclude that generalizations about the positive density-distribution relationship should be made more cautiously.Species that are locally abundant tend to be more widespread than species that are locally rare [1,2]. This positive relationship between density and distribution of species has been observed in a variety of species assemblages over a spectrum of spatial scales, and it has been suggested that it may be almost an universal pattern in ecology [3-6]. However, a few studies document a negative relationship between density and distribution [7-14] (but see [15]). Only recently Gaston et al. [5] encouraged ecologists to pay more attention to the possibility of a negative relationship.Nine mechanisms have been proposed to explain the positive relationship between density and distribution [2,3,14,16-25]. Of these, two are artefactual (sampling artefact, phylogenetic non-independence) and seven are ecological (pattern of a
Phylogenetics and biogeography of a spectacular Old World radiation of butterflies: the subtribe Mycalesina (Lepidoptera: Nymphalidae: Satyrini)
Ullasa Kodandaramaiah, David C Lees, Chris J Müller, Elizabeth Torres, K Praveen Karanth, Niklas Wahlberg
BMC Evolutionary Biology , 2010, DOI: 10.1186/1471-2148-10-172
Abstract: The results indicate that the group Mycalesina radiated rapidly around the Oligocene-Miocene boundary. Basal relationships are unresolved, but we recover six well-supported clades. Some species of Mycalesis are nested within a primarily Madagascan clade of Heteropsis, while Nirvanopsis is nested within Lohora. The phylogeny suggests that the group had its origin either in Asia or Africa, and diversified through dispersals between the two regions, during the late Oligocene and early Miocene. The current dataset tentatively suggests that the Madagascan fauna comprises two independent radiations. The Australasian radiation shares a common ancestor derived from Asia. We discuss factors that are likely to have played a key role in the diversification of the group.We propose a significantly revised classification scheme for Mycalesina. We conclude that the group originated and radiated from an ancestor that was found either in Asia or Africa, with dispersals between the two regions and to Australasia. Our phylogeny paves the way for further comparative studies on this group that will help us understand the processes underlying diversification in rapid radiations of invertebrates.Knowledge of phylogenetic relationships among the species comprising a rapid radiation has proved invaluable for detailed investigations into the processes and patterns of their diversification. There are still relatively few studies aimed at understanding the mechanisms of radiations for invertebrates, even in popular groups such as butterflies which feature prominent model-organisms in evolutionary biology [1]. It is the lack of robust phylogenies for such groups that has imposed a crucial impediment for comparative analyses. Among butterflies, a phylogenetic perspective has been applied to a number of radiations (e.g. [2-6]). However, few butterfly groups can compare with the mycalesine radiation (Nymphalidae: Satyrinae: Satyrini: Mycalesina) in terms of diversity of species and geographic swee
Cuban Calisto (Lepidoptera, Nymphalidae, Satyrinae), a review based on morphological and DNA data
Rayner Nú?ez Aguila,Edelquis Plasencia,Pavel Matos Maravi,Niklas Wahlberg
ZooKeys , 2012, DOI: 10.3897/zookeys.165.2206
Abstract: The Cuban species of Calisto are reviewed based on the morphology of adult and immature stages, as well as DNA sequences of six genes (COI, EF1α, wingless, GAPDH, RpS5, CAD). A new species, Calisto occulta sp. n., is described from the northeastern Cuban mountains. Calisto smintheus Bates, 1935 and C. bruneri, Michener 1949 are revised and revalidated. A new status, the species level, is proposed for C. brochei, Torre 1973, C. muripetens, Bates 1939 and C. bradleyi, Munroe 1950. The immature stages of C. smintheus, C. brochei, and C. occulta are described for the first time, and those of C. herophile, Hübner 1823 are redescribed. Useful morphological characters for adults are the shape and conspicuousness of androconial patch, the number and relative size of white dots on underside of hindwing, the shape of aedeagus, the shape of digitiform projection of genitalia valve, the shape and relative size of tegumen and uncus, the relative size of female genitalia, the height of sterigmal ring dorsal crown of the latter, and the relative size of corpus bursae and ductus bursae. For the immature stages, the most important characters are the color pattern of head capsule, the number and width of longitudinal lines of body, in the larvae; and the color pattern and the absence or presence of dorsal ridges on the abdomen of pupae. The phylogenetic relationships between the Cuban Calisto species are quite robust and well-supported; however, conflict between mitochondrial and nuclear datasets was detected in C. brochei, C. muripetens and to a lesser degree in C. bradleyi.
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