Research (under construction)

My main research interest revolves around what can be referred to as Evolutionary Ecophysiology, in which function and mechanism are linked to better understand behaviour from an evolutionary perspective. In this context we are interested in the physiological and behavioural mechanisms mediating the trade-offs that constitute the selection pressures that shaped behaviour over evolutionary time. We focus on the two main life-history trade-offs: (1) between number and quality of offspring, and (2) between current and future reproduction (also known as ‘costs of reproduction’). The latter trade-off is of particular interest since the costs of reproduction are conceptually identical with senescence acceleration, which is also a core interest.

 

Current project themes include:

· Resource allocation and its fitness consequences : The trade-off between resources allocated to activities that increase fitness in the near future (e.g. reproduction, signalling, thermoregulation, foraging), at the expense to resources allocated to somatic maintenance and repair, which benefits future fitness, is central in much of our functional understanding of animal behaviour. We manipulate this trade-off in zebra finches to study the fitness consequences and the mediating mechanisms (PhD-project Egbert Koetsier) and quantified resource allocation to reproduction in mice working for food (PhD-project Kristin Schubert).

· Evolutionary ecology of (basal) metabolic rate : BMR has been measured many times in many species, but we know surprisingly little about the causes and consequences of individual variation in metabolic rate, in particular in free-living animals. Sandra Bouwhuis measured BMR in a large number of free-living Great Tits in Wytham Wood (U.K.) to explore this topic as part of her PhD-project, which is carried out in close collaboration with Prof. Ben Sheldon ( Oxford University ). Simultaneously Martijn Salomons measured BMR for his PhD-project in free-living Jackdaws prior to the breeding season to explore its relation to age, social dominance and subsequent reproductive success.

· Telomeres are regions of non-coding DNA at the end of linear chromosomes, consisting of tandem repeated highly conserved DNA sequence (5’-TTAGGG-3’)_n, . There are indications that telomere length predicts remaining life span, possibly because telomere-shortening rate is accelerated by oxidative stress. We study telomeres and their relation to age, survival and reproduction using pulsed field gel electrophoresis applied under supervision of Ellis Mulder. In addition to our ‘own’ study species (Jackdaw – Martijn Salomons, Zebra Finch - Egbert Koetsier, Great Tit – Sandra Bouwhuis) we study telomere shortening in Oystercatchers in collaboration with Kees Oosterbeek (SOVON), and in Common Terns in collaboration with Christina Bauch, a PhD-student supervised by Prof. Peter Becker (Vogelwarte Helogoland, Wilhelmshafen).

· Oxidative stress, defined as the rate at which oxidative damage is generated, may give rise to pathological conditions and is increasingly implicated as a contributing factor to several human pathologies, cellular senescence, and aging. We study oxidative stress in relation to (manipulated) energy expenditure, age, telomere shortening and the two main life-history trade-offs. Studying oxidative stress is part of the PhD-projects of Egbert Koetsier, Martijn Salomons and Mirre Simons.

· Meta-analysis is a useful tool to develop a quantitative synthesis of research results. We meta-analyse brood size manipulation studies to answer questions regarding avian life-history evolution.

 

Click here a video of a recent talk (in Dutch).

 

Selected recent publications (see my ResearcherID for complete list):

• S Bouwhuis, R. Choquet, BC Sheldon & S Verhulst. The forms and fitness cost of senescence: age-specific recapture, survival, reproduction and reproductive value in a wild bird population. Am Nat
• J Grasman, HM Salomons & S Verhulst 2011. Stochastic modelling of telomere shortening in Corvus monedula. Journal of Theoretical Biology 282, 1-6.
• MJP Simons & S Verhulst 2011. Zebra finch females prefer males with red bills, independent of song rate; a meta-analysis. Behavioral Ecology 22, 755-762.
• PJ van der Most, B de Jong, HK Parmentier & S Verhulst 2011. Trade-off between growth and immunocompetence: a meta-analysis of selection experiments. Functional Ecology 25, 74-80.
• HM Salomons, GA Mulder, M Linskens, M Haussmann, L. van de Zande & S Verhulst 2009. Telomere shortening patterns and survival in free-living corvids. Proc R Soc 276: 3157-3165.
• S Bouwhuis, BC Sheldon, S Verhulst & A Charmantier 2009. Great tits growing old: selective disappearance and the partitioning of senescence to stages within the breeding cycle. Proc R Soc 276: 2769 - 3165.
• KA Schubert, G de Vries, LM Vaanholt, H Meijer, S Daan & S Verhulst 2009. Maternal energy allocation to offspring increases with environmental quality in house mice. Am Nat 173: 831 - 840.
• D Costantini & S Verhulst 2009. Does high antioxidant capacity indicate low oxidative stress? Funct Ecol 23: 506-509.
• B Moe, B Rønning, S Verhulst & C Bech 2009. Metabolic ageing in individual zebra finches. Biol Lett 5: 86-89.
• JJ Boonekamp, AFH Ros & S Verhulst 2008. Immune activation suppresses plasma testosterone level; A meta-analysis. Biol Lett 4: 741-744.
• S Verhulst & J-Å Nilsson 2008. The Timing of Birds' Breeding Seasons; A review of experiments that manipulated timing of breeding. Phil Trans Roy Soc Ser B 363: 399-410.
• KA Spencer & S Verhulst 2007. Delayed behavioral effects of post-natal exposure to corticosterone in the zebra finch (Taeniopygia guttata). Horm & Behav 51: 273-280.
• S Verhulst, MJ Holveck & K Riebel 2006. Long-term effects of manipulated natal brood size on metabolic rate in the zebra finch. Biol Lett 2: 478-480.
• M van de Pol & S Verhulst 2006. Age-dependent traits: a new statistical method to separate within and between-individual effects. Am Nat 167: 766-773.
• AL Rutten, K Oosterbeek, BJ Ens & S Verhulst 2006. Optimal foraging on perilous prey: risk of bill damage reduces optimal prey size in oystercatchers. Behav Ecol 17: 297-302.
• M van de Pol, LW Bruinzeel, D Heg, HP van der Jeugd & S Verhulst 2006. A silver spoon for a golden future: effects of natal habitat quality on fitness prospects of European oystercatchers (Haematopus ostralegus). J Anim Ecol 75: 616-626.

 

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