uu.seUppsala University Publications
Change search
Link to record
Permanent link

Direct link
BETA
Alternative names
Publications (10 of 136) Show all publications
Björklund, M. (2019). Be careful with your principal components. Evolution, 73(10), 2151-2158
Open this publication in new window or tab >>Be careful with your principal components
2019 (English)In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 73, no 10, p. 2151-2158Article in journal, Editorial material (Other academic) Published
Abstract [en]

Principal components analysis (PCA) is a common method to summarize a larger set of correlated variables into a smaller and more easily interpretable axes of variation. However, the different components need to be distinct from each other to be interpretable otherwise they only represent random directions. This is a fundamental assumption of PCA and, thus, needs to be tested every time. Sample correlation matrices will always result in a pattern of decreasing eigenvalues even if there is no structure. Tests are, therefore, needed to discern real patterns from illusionary ones. Furthermore, the loadings of the vectors need to be larger than expected by random data to be useful in the calculation of PC-scores. PC-scores calculated from nondistinct PC's have very large standard errors and cannot be used for biological interpretations. I give a number of examples to illustrate the potential problems with PCA. Robustness of the PC's increases with increasing sample size but not with the number of traits. I review a few simple test statistics appropriate for testing PC's and use a real-world example to illustrate how this can be done using randomization tests. PCA can be very useful but great care is needed to avoid spurious results.

Keywords
Correlations, principal components analysis, randomization, standard error
National Category
Evolutionary Biology
Identifiers
urn:nbn:se:uu:diva-398530 (URN)10.1111/evo.13835 (DOI)000484684900001 ()31433858 (PubMedID)
Available from: 2019-12-06 Created: 2019-12-06 Last updated: 2019-12-06Bibliographically approved
Björklund, M. (2019). Lamarck, the Father of Evolutionary Ecology?. Trends in Ecology & Evolution, 34(10), 874-875
Open this publication in new window or tab >>Lamarck, the Father of Evolutionary Ecology?
2019 (English)In: Trends in Ecology & Evolution, ISSN 0169-5347, E-ISSN 1872-8383, Vol. 34, no 10, p. 874-875Article in journal, Editorial material (Other academic) Published
Abstract [en]

Lamarck realized life had evolved from simple to more complex forms, due to adaptation to a changing environment over time. Though he was wrong in many details, he got the overall picture right. Thus, he can be seen as the first evolutionary ecologist, connecting evolutionary change in organisms to their environment.

National Category
Evolutionary Biology
Identifiers
urn:nbn:se:uu:diva-395628 (URN)10.1016/j.tree.2019.06.010 (DOI)000486454000002 ()31300169 (PubMedID)
Available from: 2019-10-23 Created: 2019-10-23 Last updated: 2019-10-23Bibliographically approved
Curveira-Santos, G., Marques, T. A., Björklund, M. & Santos-Reis, M. (2017). Mediterranean mesocarnivores in spatially structured managed landscapes: community organisation in time and space. Agriculture, Ecosystems & Environment, 237, 280-289
Open this publication in new window or tab >>Mediterranean mesocarnivores in spatially structured managed landscapes: community organisation in time and space
2017 (English)In: Agriculture, Ecosystems & Environment, ISSN 0167-8809, E-ISSN 1873-2305, Vol. 237, p. 280-289Article in journal (Refereed) Published
Abstract [en]

In the multi-functional and biodiverse cork oak landscapes of Iberia (Montado), agro-silvo-pastoral practices promote landscape heterogeneity and create intricate habitat and resource availability patterns. We used camera-traps to investigate the temporal and spatial organisation of a mesocarnivore community in a Montado landscape in central Portugal. The target carnivore assemblage was largely dominated by three generalist species - the red fox Vulpes vulpes, the European badger Meles metes and the Egyptian mongoose Herpestes ichneumon - while remaining community members - the common genet Genetta genetta and the feral cat Felis silvestris spp. - exhibited restricted distributions. Interspecific differences in activity rhythms and habitat use were particularly marked among widespread species. Low temporal overlap was reported between the diurnal mongoose and predominantly nocturnal red fox and badger. For the latter two species, contrasting differences in habitat use were associated with anthropogenic-induced environmental heterogeneity. Whereas the red fox used more intensively Montado areas preserving dense shrubby understory and avoided semi-disturbed mosaics of sparse shrubs, the badgers displayed the opposite pattern. Our findings add to previous evidence suggesting that the spatial structure created in highly managed landscapes, particularly the diversity of resulting understory structures, promotes the abundance and spread of generalist mesocarnivore species. These may benefit from the surplus of resource amount (e.g. prey) and the creation of different human-made habitats conditions that provide particular combinations of ecological resources favourable to each species requirements. We concur the common view that maintaining understory heterogeneity in Montado landscapes, menaced by current intensification and extensification trends, is important where carnivore persistence is a relevant conservation goal, but alert for potential effects on carnivore assemblages structuring and impacts for specialist species less tolerant to disturbance.

Keywords
Community structure, Carnivora, Agro-forestry systems, Montado, Landscape heterogeneity, Camera-trapping
National Category
Biological Sciences
Identifiers
urn:nbn:se:uu:diva-317611 (URN)10.1016/j.agee.2016.12.037 (DOI)000393252200029 ()
Available from: 2017-03-16 Created: 2017-03-16 Last updated: 2017-11-29Bibliographically approved
Riyahi, S., Björklund, M., Mateos-Gonzalez, F. & Carlos Senar, J. (2017). Personality and urbanization: behavioural traits and DRD4 SNP830 polymorphisms in great tits in Barcelona city. Journal of ethology, 35(1), 101-108
Open this publication in new window or tab >>Personality and urbanization: behavioural traits and DRD4 SNP830 polymorphisms in great tits in Barcelona city
2017 (English)In: Journal of ethology, ISSN 0289-0771, E-ISSN 1439-5444, Vol. 35, no 1, p. 101-108Article in journal (Refereed) Published
Abstract [en]

Most examples of adaptation to the urban environment relate to plasticity processes rather than to natural selection. Personality, however, defined as consistent individual differences in behaviour related to exploration, caution, and neophobia, is a good behavioural candidate character to study natural selection in relation to the urban habitat due to its heritable variation. The aim of this paper was to analyse variation in personality by comparing urban and forest great tits Parus major using standard tests of exploratory behaviour and boldness. We studied personality in 130 wild great tits captured in Barcelona city and nearby forests and found that urban birds were more explorative and bolder towards a novel object than forest birds. Genotype frequencies of the DRD4 SNP830 polymorphism, a gene region often associated with personality variation, varied significantly between forest and urban birds. Behavioural scores, however, were not correlated with this polymorphism in our population. Exploration scores correlated to boldness for forest birds but not for urban birds. Our findings suggest that the novel selection pressures of the urban environment favour the decoupling of behavioural traits that commonly form behavioural syndromes in the wild.

Keywords
Parus major, Urban, Boldness, Exploratory behaviour, Candidate gene
National Category
Zoology
Identifiers
urn:nbn:se:uu:diva-316057 (URN)10.1007/s10164-016-0496-2 (DOI)000392031600012 ()
Available from: 2017-02-23 Created: 2017-02-23 Last updated: 2017-11-29Bibliographically approved
Svengren, H., Prettejohn, M., Bunge, D., Fundi, P. & Björklund, M. (2017). Relatedness and genetic variation in wild and captive populations of Mountain Bongo in Kenya obtained from genome-wide single-nucleotide polymorphism (SNP) data. Global Ecology and Conservation, 11, 196-206
Open this publication in new window or tab >>Relatedness and genetic variation in wild and captive populations of Mountain Bongo in Kenya obtained from genome-wide single-nucleotide polymorphism (SNP) data
Show others...
2017 (English)In: Global Ecology and Conservation, ISSN 2351-9894, Vol. 11, p. 196-206Article in journal (Refereed) Published
Abstract [en]

To assess the relatedness and amount of genetic variation of wild and captive Mountain Bongo Tragelaphus eurycerus ssp. isaaci, both non-invasive and invasive samples were efficiently analyzed using SNP's. Mountain Bongo is estimated to remain in Kenyan forest with less than 96 individuals, possibly as low as 73 individuals, split in five subpopulations whereof four populations are isolated from each other. The genetic diversity of wild animals was studied using fecal samples, and using tissue samples from the 62 animals presently held captive at the Mount Kenya Wildlife Conservancy. In strategic conservation of the wild Mountain Bongo, the captive animals constitute a potential genetic input to wild populations. Our study shows there is still genetic variation in the wild population and that the subpopulations are to some extent genetically differentiated. This leads to an overall effective population size of around 14 in the wild population, which is good relative to the small population, but dangerously small for long-term, or even short-term, survival. Most individuals in the wild population were unrelated, while in the captive population most individuals were related at the level of half-sibs. The captive population still host genetic variation and is differentiated slightly to the wild population. Careful restocking from the captive populations could be an effective means to enhance the genetic variation in the wild, but most importantly make the dwindling population less vulnerable to stochastic events.

Keywords
Heterozygosity, Relatedness, Effective population size, Conservation, SNP's, Bongo, Kenya
National Category
Ecology
Identifiers
urn:nbn:se:uu:diva-340165 (URN)10.1016/j.gecco.2017.07.001 (DOI)000413278900018 ()
Available from: 2018-01-31 Created: 2018-01-31 Last updated: 2018-01-31Bibliographically approved
Björklund, M. & Gustafsson, L. (2017). Subtle but ubiquitous selection on body size in a natural population of collared flycatchers over 33years. Journal of Evolutionary Biology, 30(7), 1386-1399
Open this publication in new window or tab >>Subtle but ubiquitous selection on body size in a natural population of collared flycatchers over 33years
2017 (English)In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 30, no 7, p. 1386-1399Article in journal (Refereed) Published
Abstract [en]

Understanding the magnitude and long-term patterns of selection in natural populations is of importance, for example, when analysing the evolutionary impact of climate change. We estimated univariate and multivariate directional, quadratic and correlational selection on four morphological traits (adult wing, tarsus and tail length, body mass) over a time period of 33years (approximate to 19000 observations) in a nest-box breeding population of collared flycatchers (Ficedula albicollis). In general, selection was weak in both males and females over the years regardless of fitness measure (fledged young, recruits and survival) with only few cases with statistically significant selection. When data were analysed in a multivariate context and as time series, a number of patterns emerged; there was a consistent, but weak, selection for longer wings in both sexes, selection was stronger on females when the number of fledged young was used as a fitness measure, there were no indications of sexually antagonistic selection, and we found a negative correlation between selection on tarsus and wing length in both sexes but using different fitness measures. Uni- and multivariate selection gradients were correlated only for wing length and mass. Multivariate selection gradient vectors were longer than corresponding vector of univariate gradients and had more constrained direction. Correlational selection had little importance. Overall, the fitness surface was more or less flat with few cases of significant curvature, indicating that the adaptive peak with regard to body size in this species is broader than the phenotypic distribution, which has resulted in weak estimates of selection.

Keywords
body size, collared flycatcher, multivariate selection, reproduction, survival, time series
National Category
Evolutionary Biology
Identifiers
urn:nbn:se:uu:diva-330009 (URN)10.1111/jeb.13117 (DOI)000405355100012 ()
Funder
Swedish Research CouncilSwedish Research Council Formas
Available from: 2017-10-11 Created: 2017-10-11 Last updated: 2017-10-11Bibliographically approved
Lohmus, M. & Björklund, M. (2015). Climate change: what will it do to fish-parasite interactions?. Biological Journal of the Linnean Society, 116(2), 397-411
Open this publication in new window or tab >>Climate change: what will it do to fish-parasite interactions?
2015 (English)In: Biological Journal of the Linnean Society, ISSN 0024-4066, E-ISSN 1095-8312, Vol. 116, no 2, p. 397-411Article, review/survey (Refereed) Published
Abstract [en]

Climate change-related factors are predicted to affect aquatic environments in many ways. Fish physiology, immunology, behaviour, and parasite-avoidance strategies are likely to be affected by climate change and this may lead to ecosystem-level changes. Parasitic organisms that exploit fish are also likely to be affected by climate change, both directly and via climate effects on their hosts. It is possible that climate change will alter the prerequisites for parasite transfer, for example, through changes in phenological relationships, and/or change the direction and pressure of selection in host-parasite relationships. Our review indicates strong multifactorial effects of climate change on fish-parasite systems. Increased water temperature is, on the one hand, predicted to enhance parasite metabolism, resulting in more rapid spread of parasites; on the other hand, the occurrence of some parasites could also decrease if the optimal temperature for growth and transmission is exceeded.

Keywords
aquatic systems, global warming, macroparasites, models, phenology
National Category
Evolutionary Biology
Identifiers
urn:nbn:se:uu:diva-265954 (URN)10.1111/bij.12584 (DOI)000361198500013 ()
Funder
Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning
Available from: 2015-11-05 Created: 2015-11-04 Last updated: 2017-12-01Bibliographically approved
Björklund, M., Borras, A., Cabrera, J. & Senar, J. C. (2015). Increase in body size is correlated to warmer winters in a passerine bird as inferred from time series data. Ecology and Evolution, 5(1), 59-72
Open this publication in new window or tab >>Increase in body size is correlated to warmer winters in a passerine bird as inferred from time series data
2015 (English)In: Ecology and Evolution, ISSN 2045-7758, E-ISSN 2045-7758, Vol. 5, no 1, p. 59-72Article in journal (Refereed) Published
Abstract [en]

Climate change is expected to affect natural populations in many ways. One way of getting an understanding of the effects of a changing climate is to analyze time series of natural populations. Therefore, we analyzed time series of 25 and 20years, respectively, in two populations of the citril finch (Carduelis citrinella) to understand the background of a dramatic increase in wing length in this species over this period, ranging between 1.3 and 2.9 phenotypic standard deviations. We found that the increase in wing length is closely correlated to warmer winters and in one case to rain in relation to temperature in the summer. In order to understand the process of change, we implemented seven simulation models, ranging from two nonadaptive models (drift and sampling), and five adaptive models with selection and/or phenotypic plasticity involved and tested these models against the time series of males and females from the two population separately. The nonadaptive models were rejected in each case, but the results were mixed when it comes to the adaptive models. The difference in fit of the models was sometimes not significant indicating that the models were not different enough. In conclusion, the dramatic change in mean wing length can best be explained as an adaptive response to a changing climate.

Keywords
Citril finch, climate change, phenotypic evolution, plasticity, selection, time series
National Category
Ecology
Identifiers
urn:nbn:se:uu:diva-243665 (URN)10.1002/ece3.1323 (DOI)000347517300006 ()25628864 (PubMedID)
Available from: 2015-02-20 Created: 2015-02-11 Last updated: 2017-12-04Bibliographically approved
Björklund, M., Aho, T. & Behrmann-Godel, J. (2015). Isolation over 35 years in a heated biotest basin causes selection on MHC class II beta genes in the European perch (Perca fluviatilis L.). Ecology and Evolution, 5(7), 1440-1455
Open this publication in new window or tab >>Isolation over 35 years in a heated biotest basin causes selection on MHC class II beta genes in the European perch (Perca fluviatilis L.)
2015 (English)In: Ecology and Evolution, ISSN 2045-7758, E-ISSN 2045-7758, Vol. 5, no 7, p. 1440-1455Article in journal (Refereed) Published
Abstract [en]

Genes that play key roles in host immunity such as the major histocompatibility complex (MHC) in vertebrates are expected to be major targets of selection. It is well known that environmental conditions can have an effect on host-parasite interactions and may thus influence the selection on MHC. We analyzed MHC class II ss variability over 35years in a population of perch (Perca fluviatilis) from the Baltic Sea that was split into two populations separated from each other. One population was subjected to heating from cooling water of a nuclear power plant and was isolated from the surrounding environment in an artificial lake, while the other population was not subjected to any change in water temperature (control). The isolated population experienced a change of the allelic composition and a decrease in allelic richness of MHC genes compared to the control population. The two most common MHC alleles showed cyclic patterns indicating ongoing parasite-host coevolution in both populations, but the alleles that showed a cyclic behavior differed between the two populations. No such patterns were observed at alleles from nine microsatellite loci, and no genetic differentiation was found between populations. We found no indications for a genetic bottleneck in the isolated population during the 35years. Additionally, differences in parasitism of the current perch populations suggest that a change of the parasite communities has occurred over the isolation period, although the evidence in form of in-depth knowledge of the change of the parasite community over time is lacking. Our results are consistent with the hypothesis of a selective sweep imposed by a change in the parasite community.

Keywords
MHC II, microsatellites, Perca fluviatilis, selection, time series, warming
National Category
Ecology Evolutionary Biology
Identifiers
urn:nbn:se:uu:diva-252183 (URN)10.1002/ece3.1426 (DOI)000352560000008 ()25897384 (PubMedID)
Available from: 2015-05-06 Created: 2015-05-04 Last updated: 2017-12-04Bibliographically approved
Riyahi, S., Björklund, M., Ödeen, A. & Carlos Senar, J. (2015). No association between the melanocortin-1 receptor (MC1R) and black belly stripe size variation in the Great Tit Parus major. Bird Study, 62(1), 150-152
Open this publication in new window or tab >>No association between the melanocortin-1 receptor (MC1R) and black belly stripe size variation in the Great Tit Parus major
2015 (English)In: Bird Study, ISSN 0006-3657, E-ISSN 1944-6705, Vol. 62, no 1, p. 150-152Article in journal (Refereed) Published
Abstract [en]

Capsule The Great Tit Parus major displays a black melanin breast patch stripe (black tie or black belly stripe) which shows great variation and its size correlates with male breeding success, survival and dominance. We investigated for associations between the melanocortin-1 receptor (MC1R) polymorphism, which has an important function in melanin colouration, and the size of the black belly stripe but were unable to detect any polymorphism in this gene. Variation in the size of the melanin-based black belly stripe may therefore be regulated through genetic variation at other genes or via modification of the gene expression inside the melanocortin system and melanogenesis.

National Category
Zoology
Identifiers
urn:nbn:se:uu:diva-247171 (URN)10.1080/00063657.2014.988601 (DOI)000349155200018 ()
Available from: 2015-03-16 Created: 2015-03-13 Last updated: 2017-12-04Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-5436-6989

Search in DiVA

Show all publications