| 1. |
- Bijl, Wouter, et al.
(author)
-
Butterfly dichromatism primarily evolved via Darwin's, not Wallace's, model
- 2020
-
In: Evolution letters. - : Oxford University Press (OUP). - 2056-3744. ; 4:6, s. 545-555
-
Journal article (peer-reviewed)abstract
- Sexual dimorphism is typically thought to result from sexual selection for elaborated male traits, as proposed by Darwin. However, natural selection could reduce expression of elaborated traits in females, as proposed by Wallace. Darwin and Wallace debated the origins of dichromatism in birds and butterflies, and although evidence in birds is roughly equal, if not in favor of Wallace's model, butterflies lack a similar scale of study. Here, we present a large‐scale comparative phylogenetic analysis of the evolution of butterfly coloration, using all European non‐hesperiid butterfly species (n = 369). We modeled evolutionary changes in coloration for each species and sex along their phylogeny, thereby estimating the rate and direction of evolution in three‐dimensional color space using a novel implementation of phylogenetic ridge regression. We show that male coloration evolved faster than female coloration, especially in strongly dichromatic clades, with male contribution to changes in dichromatism roughly twice that of females. These patterns are consistent with a classic Darwinian model of dichromatism via sexual selection on male coloration, suggesting this model was the dominant driver of dichromatism in European butterflies.
|
|
| 2. |
- Brehm, Gunnar, et al.
(author)
-
Moth body size increases with elevation along a complete tropical elevational gradient for two hyperdiverse clades
- 2019
-
In: Ecography. - : Wiley. - 0906-7590 .- 1600-0587. ; 42:4, s. 632-642
-
Journal article (peer-reviewed)abstract
- The body size of an animal is probably its most important functional trait. For arthropods, environmental drivers of body size variation are still poorly documented and understood, especially in tropical regions. We use a unique dataset for two species-rich, phylogenetically independent moth taxa (Lepidoptera: Geometridae; Arctiinae), collected along an extensive tropical elevational gradient in Costa Rica, to investigate the correlates and possible causes of body-size variation. We studied 15 047 specimens (794 species) of Geometridae and 4167 specimens (308 species) of Arctiinae to test the following hypotheses: 1) body size increases with decreasing ambient temperature, as predicted by the temperature-size rule; 2) body size increases with increasing rainfall and primary productivity, as predicted from considerations of starvation resistance; and 3) body size scales allometrically with wing area, as elevation increases, such that wing loading (the ratio of body size to wing area) decreases with increasing elevation to compensate for lower air density. To test these hypotheses, we examined forewing length as a proxy for body size in relation to ambient temperature, rainfall, vegetation index and elevation as explanatory variables in linear and polynomial spatial regression models. We analysed our data separately for males and females using two principal approaches: mean forewing length of species at each site, and mean forewing length of complete local assemblages, weighted by abundance. Body size consistently increased with elevation in both taxa, both approaches, both sexes, and also within species. Temperature was the best predictor for this pattern (-0.98 < r < -0.74), whereas body size was uncorrelated or weakly correlated with rainfall and enhanced vegetation index. Wing loading increased with elevation. Our results support the temperature-size rule as an important mechanism for body size variation in arthropods along tropical elevational gradients, whereas starvation resistance and optimization of flight mechanics seem to be of minor importance.
|
|
| 3. |
- Dormann, Carsten F., et al.
(author)
-
Biotic interactions in species distribution modelling : 10 questions to guide interpretation and avoid false conclusions
- 2018
-
In: Global Ecology and Biogeography. - : Wiley. - 1466-822X .- 1466-8238. ; 27:9, s. 1004-1016
-
Journal article (peer-reviewed)abstract
- Aim: Recent studies increasingly use statistical methods to infer biotic interactions from co‐occurrence information at a large spatial scale. However, disentangling biotic interactions from other factors that can affect co‐occurrence patterns at the macroscale is a major challenge.Approach: We present a set of questions that analysts and reviewers should ask to avoid erroneously attributing species association patterns to biotic interactions. Our questions relate to the appropriateness of data and models, the causality behind a correlative signal, and the problems associated with static data from dynamic systems. We summarize caveats reported by macroecological studies of biotic interactions and examine whether conclusions on the presence of biotic interactions are supported by the modelling approaches used.Findings: Irrespective of the method used, studies that set out to test for biotic interactions find statistical associations in species’ co‐occurrences. Yet, when compared with our list of questions, few purported interpretations of such associations as biotic interactions hold up to scrutiny. This does not dismiss the presence or importance of biotic interactions, but it highlights the risk of too lenient interpretation of the data. Combining model results with information from experiments and functional traits that are relevant for the biotic interaction of interest might strengthen conclusions.Main conclusions: Moving from species‐ to community‐level models, including biotic interactions among species, is of great importance for process‐based understanding and forecasting ecological responses. We hope that our questions will help to improve these models and facilitate the interpretation of their results. In essence, we conclude that ecologists have to recognize that a species association pattern in joint species distribution models will be driven not only by real biotic interactions, but also by shared habitat preferences, common migration history, phylogenetic history and shared response to missing environmental drivers, which specifically need to be discussed and, if possible, integrated into models.
|
|
| 4. |
- Pinkert, Stefan, et al.
(author)
-
Thermal Biology : Melanin-Based Energy Harvesting across the Tree of Life
- 2018
-
In: Current Biology. - : Elsevier BV. - 0960-9822 .- 1879-0445. ; 28:16, s. R887-R889
-
Journal article (other academic/artistic)abstract
- Recent results on the thermal biology of unicellular fungi provide evidence that pigmentation is an ancient adaptation for harvesting solar radiation. A new model system promises novel opportunities for quantifying radiative heat transfer and improving biophysical models.
|
|
| 5. |
- Stelbrink, Pablo, et al.
(author)
-
Colour lightness of butterfly assemblages across North America and Europe
- 2019
-
In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9
-
Journal article (peer-reviewed)abstract
- Melanin-based dark colouration is beneficial for insects as it increases the absorption of solar energy and protects against pathogens. Thus, it is expected that insect colouration is darker in colder regions and in regions with high humidity, where it is assumed that pathogen pressure is highest. These relationships between colour lightness, insect distribution, and climate between taxa and subtaxa across continents have never been tested and compared. Here we analysed the colour lightness of nearly all butterfly species of North America and Europe using the average colour lightness of species occurring within 50 km x 50 km grid cells across both continents as the dependent variable and average insolation, temperature and humidity within grid cells as explanatory variables. We compared the direction, strength and shape of these relationships between butterfly families and continents. On both continents, butterfly assemblages in colder and more humid regions were generally darker coloured than assemblages in warmer and less humid regions. Although these relationships differed in detail between families, overall trends within families on both continents were similar. Our results add further support for the importance of insect colour lightness as a mechanistic adaptation to climate that influences biogeographical patterns of species distributions.
|
|
