Tjaša Lokovšek

Tjaša Lokovšek
Research Centre of the Slovenian Academy of Sciences and Arts | ZRC SAZU · Jovan Hadži Institute of Biology

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18
Publications
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214
Citations

Publications

Publications (18)
Article
Full-text available
Adult body size, development time, and growth rates are components of organismal life histories, which crucially influence fitness and are subject to trade-offs. If selection is sex-specific, male and female developments can eventually lead to different optimal sizes. This can be achieved through developmental plasticity and sex-specific developmen...
Article
Full-text available
Instances of sexual size dimorphism (SSD) provide the context for rigorous tests of biological rules of size evolution, such as Cope's rule (phyletic size increase), Rensch's rule (allometric patterns of male and female size), as well as male and female body size optima. In certain spider groups, such as the golden orbweavers (Nephilidae), extreme...
Preprint
Full-text available
Instances of sexual size dimorphism (SSD) provide the context for rigorous tests of biological rules of size evolution, such as Copes Rule (phyletic size increase), Renschs Rule (allometric patterns of male and female size), as well as male and female body size optima. In certain spider groups, such as the golden orbweavers (Nephilidae), extreme fe...
Article
Full-text available
Though not uncommon in other animals, heterospecific mating is rarely reported in arachnids. We investigated sexual interactions among four closely related and syntopical African golden orbweb spiders, Nephila inaurata, N. fenestrata, N. komaci, and N. senegalensis. In two South African localities, female webs were often inhabited by heterospecific...
Article
Full-text available
The use of unique DNA sequences as a method for taxonomic identification is no longer fundamentally controversial, even though debate continues on the best markers, methods, and technology to use. Although both existing databanks such as GenBank and BOLD, as well as reference taxonomies, are imperfect, in best case scenarios ''barcodes'' (whether s...
Data
The results of the barcode matching test.
Data
Original sequences this project submitted to BOLD and GenBank (only those on GenBank are also publically available on BOLD, for all others, see http://ezlab.zrc-sazu.si/dna/). Legend: MNH, SI = National Museum of Natural History, Smithsonian Institution; EZ LAB = Evolutionary Zoology Lab, ZRC SAZU; NMBE = Naturhistorisches Museum der Burgergemeinde...
Data
The downloaded sequences used in the species comparison.
Article
Full-text available
Keywords: aggressive spillover mate size difference mating personality sexual cannibalism voracity Intersexual agonistic encounters prior to mating are thought to result from the 'spillover' of the advantages of a voracious personality within a foraging context that is maladaptive in a mating context. We tested this idea by examining the repeatabil...
Preprint
Full-text available
The use of unique DNA sequences as a method for taxonomic identification is no longer fundamentally controversial, even though debate continues on the best markers, methods, and technology to use. Although both existing databanks such as GenBank and BOLD, as well as reference taxonomies, are imperfect, in best case scenarios “barcodes” (whether sin...
Preprint
Full-text available
The use of unique DNA sequences as a method for taxonomic identification is no longer fundamentally controversial, even though debate continues on the best markers, methods, and technology to use. Although both existing databanks such as GenBank and BOLD, as well as reference taxonomies, are imperfect, in best case scenarios “barcodes” (whether sin...
Article
Full-text available
Urbanization poses serious extinction risks, yet some species thrive in urban environments. This may be due to a pronounced developmental plasticity in these taxa, since phenotypically, plastic organisms may better adjust to unpredictable urban food resources. We studied phenotypic plasticity in Nuctenea umbratica, a common European forest and urba...
Article
Full-text available
We investigated the mating biology of the previously unstudied central European spider Leviellus thorelli (Ausserer 1871) by staging laboratory mating trials using males and females of varying mating histories. Our aim was to seek common themes in sexual behaviors of the sexually size-monomorphic ''zygiellid'' spiders with their putatively close re...
Article
The pantropical orb web spider family Nephilidae is known for the most extreme sexual size dimorphism among terrestrial animals. Numerous studies have made Nephilidae, particularly Nephila, a model lineage in evolutionary research. However, a poorly understood phylogeny of this lineage, relying only on morphology, has prevented thorough evolutionar...

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Project (1)
Project
Females and males commonly differ in the expression of traits. The evolution of sexual dimorphism requires sex-specific selection and at least partly independent genetic variation between the sexes. However, females and males share an almost identical genome that constrains the sexes to respond independently to the selection and may result in a stage when one or both sexes express traits outside their optima. Quantitative genetics provides tools to predict the extent to which the evolution of sexual dimorphism is genetically constrained between sexes by assessing the cross-sex genetic correlation. The cross‐sex genetic correlation can be estimated as rmf =COVAmf∕sqrt(VAf ∗VAm), where COVAmf is the additive genetic covariance between the sexes, and VAm and VAf are additive genetic variances of males and females, respectively. When is close to unity, the sexes are assumed to have a nearly identical genetic architecture for the trait and evolution of sexual dimorphism should be constrained; close to zero values of rmf indicate complete independence in the genetic architecture of the trait between males and females and thus sex independent evolution. A cross‐sex genetic correlation between zero and one suggests that some of the genes acting on the shared trait already differ between males and females and indicates a further possibility for the evolution of sexual dimorphism in the trait. In this project, we aim to assess genetic variances and cross‐sex genetic correlations of size in an extremely sexually-size dimorphic spider, Nephilinis cruentata. In these spiders, females are considerably larger than males, they weigh more than 70X more than males. Our preliminary analyses found rmf close to zero suggesting that females and males do not share genetic architecture for size, indicates a resolved intra-locus sexual conflict and potential for further sex independent evolution of size. The result reflects differences in the effects of sexual and natural selection on body size between the sexes. The amount of genetic variation is significantly lower in females compared to males implying that females have been under the stronger directional selection (for fecundity) compared to males that are more plastic.