Research Bieke Vanhooydonck

Abstract

This project aims to identify the causes of intraspecific variation in a complex signaling system, the anoline dewlap, thereby using Anolis sagrei as model species. Specifically, I will investigate how different selective forces (predation risk, sensory drive, sexual selection and species recognition) contribute to the variation in dewlap design among A. sagrei populations on different islands in the Caribbean and within one island, Cuba.

Researcher(s)

• Promoter: Van Damme Raoul
• Co-promoter: Vanhooydonck Bieke
• Fellow: Driessens Tess

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

In the current project, I aim at elucidating the role of phenotypic plasticity in the evolution of cannibalism in annual killifish (Rivulidae, Cypridontiformes). The rivulids include all American killifish and comprise more than 300 species10. One of the most diversified genera within this family, Austrolebias, is of special interest here because all species are annual and inhabit seasonal pools formed during the rainy season.

Researcher(s)

• Promoter: Van Damme Raoul
• Fellow: Vanhooydonck Bieke

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Natural populations are characterized by high levels of interindividual phenotypic variation. If the variation is discrete and different forms (i.e. morphs) are simultaneously present within one population, the variation is referred to as polymorphism. At first sight, the co-occurrence of alternative morphs appears unlikely because it implies that all morphs must have the same fitness. In this study, we will explicitly address the role of natural selection and sexual selection, alone or in combination, in the evolution of colour polymorphism in a lacertid lizard species, Podarcis melisellensis.

Researcher(s)

• Promoter: Vanhooydonck Bieke

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

From the very start (e.g. Darwin 1845, Wallace 1859), the faunas of island groups have played a special role in the growth of our understanding of evolutionary changes and speciation - and they continue to do so (e.g. Losos et al. 1997, 2004). Islands in archipelagos constitute repeated, discrete and relatively simple entities and therefore function as 'natura/laboratories' that can be used to test general theories (Whittaker 1998). The (often prominent) differences in phenotype (morphology, behaviour, ecology, life history) among island populations or between island and mainland populations are almost invariably attributed to genetic divergence, but it is often unclear which evolutionary processes (founder effect, genetic drift, natural selection, introgression, ...) induce these differences (Barton 1989, Clarke & Grant 1996). The alternative explanation, that the differences arise from phenotypic plasticity, is often not considered (Losos et al. 2000). In this project, we intend to take advantage of an exceptional opportunity to unravel the causes of fenotypic divergence among (island) populations.

Researcher(s)

• Promoter: Van Damme Raoul
• Co-promoter: Backeljau Thierry
• Co-promoter: Herrel Anthony
• Co-promoter: Vanhooydonck Bieke

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: Vanhooydonck Bieke

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: Van Damme Raoul
• Fellow: Vanhooydonck Bieke

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Islands represent interesting 'natural laboratories' for testing general (evolutionary) theories. Some cases of great phenotypic divergence (i.e. differences in morphology, behaviour, ecology) among island populations have been documented. Almost in all studies genetic divergence is assumed to underlie these interpopulational differences. In this study, we will quantify divergence in morphology, performance and ecology among populations of two Podarcis lizards (P. sicula and P. melisellensis). Additionally, the interpopulational phenotypic variation will be linked to the evolutionary history of both species and to the level of gene flow among different populations.

Researcher(s)

• Promoter: Vanhooydonck Bieke

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Quantifying performance in ecomorphological studies has traditionally been limited to traits that can be measured with ease, e.g. sprint speed. For most organisms, however, other functions, which might be harder to quantify, are ecologically relevant too. Furthermore, selection does not only act on speed per se but on various aspects of locomotor performance. So far, ecomorphological studies have not dealt with the variation in the amount of force or power organisms can generate on various substrates. From an ecomorphological perspective, the lack of force data is surprising as forces can be directly related to design traits (e.g. muscle mass) on the one hand, and to kinematics, speed and locomotor efficiency on the other. Also, forces are important in different locomotor modes, such as running, jumping, climbing, etc. From a practical perspective, however, quantifying forces in an ecomorphological context has been (nearly) impossible. Ecomorphological research is typically done under (semi-) natural conditions, on large sample sizes and relatively small organisms. Up until recently, ground reaction forces could be measured either by calculating forces from high speed video clips or by using a highly specialized force platform. Both these methods, however, are inadequate for ecomorphological research. Very recently, a new, extremely sensitive Kistler force platform (Kistler Portable Multicomponent Force Plate) has been developed. By using this force platform small forces (as small as 0.002N), generated by small organisms, such as frogs and lizards as light as 0.2g, can be measured with great accuracy. Furthermore, it is possible to measure forces under field conditions and for large sample sizes as this newly developed force platform consists of one integrated entity (i.e. amplifiers built into the force platform), it is small, light, and portable. In this study, the Kistler force platform will be used to quantify and compare jumping performance in Anolis lizards.

Researcher(s)

• Promoter: Vanhooydonck Bieke

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

The apparently perfect fit between the form of an organism and its environment had intrigued biologists for meny centuries. While 19th century naturalists explained this near perfect form-function match as the work of a `Divine Designer', Charles Darwin (1859) used the same observation as an argument for the power of evolution by natural selection. An unconditional faith in the power of natural selection as an optimizing agent, lead `traditional' evolutionary biologists to follozing the adaptationist programme. In 1983, however, Stevan Arnold proposed a method to explicitly test the presence of adaptations. He suggested breaking up the adaptation process into two components: a performance and a fitness gradient. Whereas the performance gradient is defined as the effect of variation in design on variation in performance, the fitness gradient is defined as the effect of variation in performance on variation in fitness. In most organisms, fitness is influenced not just by one, but rather by multiple performance traits simultaneously. If these performance traits pose conflicting demands on the same design traits, evolutionary trade-offs occur which may obscure ecomorphological relationships. To be able to understand the relationships between design, performance and fitness it is therefore necessary to quantify and intercorrelate various performance traits. Design conflicts can originate because natural selection s.s. and sexual selection may act in opposing ways. Sexual dimorphism is an obvious results from such a conflict. In this context, the link with fitness has seldom been tested. Hypotheses and models regarding sexual selection have been tested extensively using design traits. In most such cases, sexual traits are directly correlated to the survival and reproductive success of the individual. In this project, I study the mechanism by which these correlations come about, and why sexual traits may have negative effects. As modelorganisms I use lizards belonging to the family Lacertidae and the genus Anolis.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Vanhooydonck Bieke

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

The aim of this study is to investigate whether the ecological and behavioural radiation within the Lacertidae is paralleled by a concordant differentiation in locomotor performance and morphology. Special attention is given to the occurence and mediation of trade-offs between different locomotory types. To be able to do so, measurements of the ecology (habitat use, foraging behaviour and anti-predatory tactics), locomotor performance (sprint speed, acceleration, endurance, manoeuverability, clinging and climbing), kinematics and morphology are taken. All these analyses are conducted in a phylogenetic context.

Researcher(s)

• Promoter: Van Damme Raoul
• Fellow: Vanhooydonck Bieke

Research team(s)

Project type(s)

• Research Project

Abstract

The aim of this study is to investigate whether the ecological and behavioural radiation within the Lacertidae is paralleled by a concordant differentiation in locomotor performance and morphology. Special attention is given to the occurence and mediation of trade-offs between different locomotory types. To be able to do so, measurements of the ecology (habitat use, foraging behaviour and anti-predatory tactics), locomotor performance (sprint speed, acceleration, endurance, manoeuverability, clinging and climbing), kinematics and morphology are taken. All these analyses are conducted in a phylogenetic context.

Researcher(s)

• Promoter: Van Damme Raoul
• Fellow: Vanhooydonck Bieke

Research team(s)

Project type(s)

• Research Project