Evolution of Social and Mating Systems

This line of research focuses on aspects of the social evolution of wild cavy species that are characterised by completely different social and mating systems. For example, comparative lab studies may elucidate to what extent mate choice underlies these differences. Furthermore we investigate whether differences in reproductive physiology are adaptations to different mating systems. Finally, field studies are conducted to evaluate the adaptative value of the social systems in an ecologically relevant setting. In the course of these projects we discovered a new cavy species: the Muenster yellow-toothed cavy (Galea monasteriensis). The aim of our research is to understand how evolutionary processes lead to the diversification of social systems. Top 3 publications of our research group regarding this topic: Adrian, O; Sachser, N (2011): Diversity of social and mating systems in cavies: a review. Journal of Mammalogy 92 (1): 39-53. Asher, M; Lippmann, T; Epplen, JT; Kraus, C; Trillmich, F; Sachser, N (2008): Large males dominate: ecology, social organization, and mating system of wild cavies, the ancestors of the guinea pig. Behavioral Ecology and Sociobiology 62 (9): 1509-1521. Sachser, N; Schwarz-Weig, E; Keil, A; Epplen, JT (1999): Behavioural strategies, testis size, and reproductive success in two caviomorph rodents with different mating systems. Behaviour 136: 1203-1217. Further relevant publications: Sachser, N; Kaiser, S (2010): Meerschweinchen als Sozialstrategen. Spektrum der Wissenschaft Januar: 56-63. Kemme, K; Kaiser, S; von Engelhardt, N; Wewers, D; Groothuis, T; Sachser, N (2009): An unstable social environment affects sex ratio in guinea pigs: an adaptive maternal effect? Behaviour 146: 1513-1529. Adrian, O; Kaiser, S; Sachser, N; Jandewerth, P; Löttker, P; Epplen, JT; Hennessy, MB (2008): Female influences on pair formation, reproduction and male stress responses in a monogamous cavy (Galea monasteriensis). Hormones & Behavior 53: 403-412. Adrian, O; Dekomien, G; Epplen, JT; Sachser, N (2008): Body weight and rearing conditions of males, female choice and paternities in a small mammal, Cavia aperea. Ethology: 897-906. Hennessy, MB; Neisen, G; Bullinger, KL; Kaiser, S; Sachser, N (2006): Social organization predicts nature of infant-adult interactions in two species of wild guinea pigs (Cavia aperea and Galea monasteriensis). Journal of Comparative Psychology 120: 12-18. Adrian, O; Brockmann, I; Hohoff, C; Sachser, N (2005): Paternal behaviour in wild guinea pigs: A comparative study in three closely related species with different social and mating systems. Journal of Zoology (Lond.) 265: 97-105. Asher, M; Oliveira, ES; Sachser, N (2004): Social system and spatial organization of wild guinea pigs (Cavia aperea) in a natural low density population. Journal of Mammalogy 85: 788-796. Solmsdorff, K; Kock, D; Hohoff, C; Sachser, N (2004): Comments of the genus Galea Meyen 1833 with description of Galea monasteriensis n.sp. from Bolivia (Mammalia, Rodentia, Caviidae). Senckenbergiana biologica 84: 137-156. Trillmich, F; Kraus, C; Künkele, J; Asher, M; Clara, M; Dekomien, G; Epplen, JT; Saralegui, A; Sachser, N (2004): Species-level differentiation of two cryptic species pairs of wild cavies, genera Cavia and Galea, with a discussion of the relationship between social systems and phylogeny in the Caviinae. Canadian Journal of Zoology 82: 516-524. Hohoff, C; Franzen, K; Sachser, N (2003): Female choice in a promiscuous wild guinea pig, the yellow-toothed cavy (Galea musteloides). Behavioral Ecology and Sociobiology 53: 341-349. Hohoff, C; Solmsdorff, K; Löttker, P; Kemme, K; Epplen, JT; Cooper, TG; Sachser, N (2002): Monogamy in a new species of wild guinea pigs. Naturwissenschaften 89(10): 462-465. Touma, C; Palme, R; Sachser, N (2001): Different types of oestrus cycle in two closely related South American rodents (Cavia aperea and Galea musteloides) with different social and mating systems. Reproduction 121: 791-801. Cooper, TG; Weydert, S; Yeung, CH; Künzl, C; Sachser, N (2000): Maturation of epididymal spermatozoa in the non-domesticated guinea pigs Cavia aperea and Galea musteloides. Journal of Andrology 21 (1): 154-163. Wölbing, O; Asher, M; Bishr, Y; Kuhn, W; Sachser, N (2000): Applying GIS for investigations in behavioural biology. In: Strobl, J; Blaschke, T; Griesebner, G (ed.): Angewandte Geographische Informationsverarbeitung XII, Beiträge zum AGIT-Symposium Salzburg 2000. Herbert Wichmann Verlag, Heidelberg: 520-528. Keil, A; Epplen, JT; Sachser, N (1999): Reproductive success of males in the promiscuous-mating yellow-toothed cavy (Galea musteloides). Journal of Mammalogy 80(4): 1257-1263. Keil, A; Sachser, N (1998): Reproductive benefits from female promiscuous mating in a small mammal. Ethology 104: 897-903. Sachser, N (1998): Of domestic and wild guinea pigs: studies in sociophysiology, domestication, and social evolution. Naturwissenschaften 85: 307-317. Schwarz-Weig, E; Sachser, N (1996): Social behaviour, mating system and testes size in cuis (Galea musteloides). Zeitschrift für Säugetierkunde 61: 25-38. West-Eberhardt, MJ; Bradbury, JW; Davies, NB1Gouyon P-H; Hammerstein, P; König, B; Parker, GA; Queller, DC; Sachser, N; Slagsvold, T; Trillmich, F; Vogel, C (1987): Conflicts between and within the sexes in sexual selection. In: Bradbury, JWÂnderson MB (ed.): Sexual selection:Testing the alternatives. John Wiley & Sons, Chinchester: 180-195.

Domestication

The overwhelming majority of animals that are being kept by humans as pets, production or laboratory animals are not wild, but domestic animals. Domestic animals never lived in the wilderness, but were created from wild animals by domestication, which is one of our focal points in research. We investigate the changes in behaviour and hormonal stress responsiveness caused by this process. Our main hypothesis is that traits formed by domestication are not detrimental or even 'degenerative' but that they facilitate the animals' adaptation to living conditions in man-made environments. Top 3 publications of our research group regarding this topic: Lewejohann, L; Pickel, T; Sachser, N; Kaiser, S (2010): Wild genius - domestic fool? Spatial learning abilities of wild and domestic guinea pigs. Frontiers in Zoology: 7-9. Künzl, C; Kaiser, S; Meier, E; Sachser, N (2003): Is a wild mammal kept and reared in captivity still a wild animal? Hormones and Behavior 43: 187-196. Künzl, C; Sachser, N (1999): The behavioural endocrinology of domestication: a comparison between the domestic guinea pig (Cavia aperea f. porcellus) and its wild ancestor, the cavy (Cavia aperea). Hormones & Behavior 35: 28-37. Further relevant publications: Kaiser, S; Krüger, C; Sachser, N (2010): The guinea pig. In: Hubrecht, R; Kirkwood, J (eds): The care and management of laboratory and other research animals. 8th edition. Wiley-Blackwell, Chichester, UK.: 380-398. Sachser, N; Künzl, C; Kaiser, S (2004): The welfare of laboratory guinea pigs. In: Kalista, E (ed.): The welfare of laboratory animals. Kluwer Academic Publishers, Dordrecht, The Netherlands: 181-209. Künzl, C; Meier, E; Sachser, N (2002): Verhaltensbiologische Untersuchungen zur Anpassung von Wildmeerschweinchen an den Hausstand. In: Gansloßer, U (ed.): Gruppenmechanismen. Filander-Verlag, Fürth: 153-158. Künzl, C; Sachser, N (2000): Sozialverhalten und soziale Organisation von Wild- und Hausmeerschweinchen. Tierlaboratorium 23: 100-111. Künzl, C; Sachser, N (2000): Auswirkungen der Domestikation auf Verhalten und endokrine Anpassungsreaktionen beim Meerschweinchen. Archiv für Tierzucht, Dummerstorf 43 Sonderheft: 153-158. Künzl, C; Meier, E; Sachser, N (1999): Ist ein Wildmeerschweinchen in Menschenhand noch ein Wildtier? In: Aktuelle Arbeiten zur artgemäßen Tierhaltung 1998. KTBL-Schrift 382. Darmstadt: 107-114. Sachser, N (1998): Of domestic and wild guinea pigs: studies in sociophysiology, domestication, and social evolution. Naturwissenschaften 85: 307-317.

Development of Behaviour, Especially during the Prenatal Phase and during Adolescence

Individuals of the same species can differ greatly in terms of behavioural profiles and strategies. An analysis of the underlying causal factors assigns an important role not only to gender, age and genetic makeup, but also to environmental influences as well as learning and socialisation processes during development. While research focused almost exclusively on influences during the early postnatal period for the last decades, recent investigations (see below) revealed that prenatal influences can modulate brain and behavioural development profoundly. Important developmental processes may also take place during later periods: In group-living species, adolescence is a crucial phase of life, during which essential skills for social life are acquired in interactions with conspecifics. In domestic guinea pigs and wild cavies, we investigate how the social environment of mothers during pregnancy and lactation influences brain development, hormonal reactions and behavioural profiles of their sons and daughters. Main questions centre on which neuroendocrine processes induce different profiles and on whether traits of offspring of socially stressed mothers (infantilisation in sons / behavioural masculinisation in daughters) represent pathologies or adaptations to the environment of their mothers. Furthermore, we analyse the influence of social experiences during adolescence on behavioural profiles and hormonal stress responsiveness during adulthood. Here, we again investigate the neuroendocrine mechanisms underlying different behavioural profiles and whether these may represent adaptations to different social situations (i. e. high versus low population density). Top 3 publications of our research group regarding this topic: Sachser, N; Hennessy, MB; Kaiser, S (2011): Adaptive modulation of behavioural profiles by social stress during early phases of life and adolescence. Neuroscience and Biobehavioral Reviews 35: 1518-1533. Kaiser, S; Sachser, N (2005): The effects of prenatal social stress on behaviour: Mechanisms and function. Neuroscience and Biobehavioral Reviews 29: 283-294. Sachser, N; Lick, C; Stanzel, K (1994): The environment, hormones and aggressive behaviour - a five-year-study in guinea pigs. Psychoneuroendocrinology 19: 697-707. Further relevant publications: Siegeler, K; Sachser, N; Kaiser, S (2011): The social environment during pregnancy and lactation shapes the behavioural and hormonal profile of male offspring in wild cavies. Developmental Psychobiology 53: 575-584. Kaiser, S; Sachser, N (2009): Effects of prenatal social stress on offspring development: pathology or adaptation? Current Directions in Psychological Science 18(2): 118-121. Kemme, K; Kaiser, S; von Engelhardt, N; Wewers, D; Groothuis, T; Sachser, N (2009): An unstable social environment affects sex ratio in guinea pigs: an adaptive maternal effect? Behaviour 146: 1513-1529. Kemme, K; Kaiser, S; Sachser, N (2008): Prenatal stress does not impair coping with challenge later in life. Physiology and Behavior 93: 68-75. Kaiser, S; Sachser, N (2007): Sex-specific effects of early social stress in mammals: A study in guinea pigs. In: Encyclopedia of stress, 2nd ed.; editor in chief: George Fink. Academic Press, Oxford; Vol.3: 479-484. Kemme, K; Kaiser, S; Sachser, N (2007): Prenatal maternal programming determines testosterone response during social challenge. Hormones and Behavior 51: 387-394. Wewers, D; Kaiser, S; Sachser, N (2005): Application of an antiandrogen during pregnancy infantilizes the male offsprings' behaviour. Behavioural Brain Research 158: 89-95. Kaiser, S; Heemann, K; Straub, RH; Sachser, N (2003): The social environment affects behaviour and androgens, but not cortisol in pregnant female guinea pigs. Psychoneuroendocrinology 28: 67-83. Kaiser, S; Kruijver, FPM; Straub, RH; Sachser, N; Swaab, DF (2003): Early social stress in male guinea pigs changes social behaviour, and autonomic and neuroendocrine functions. The Journal of Neuroendocrinology 15: 761-769. Kaiser, S; Kruijver, FPM; Swaab, DF; Sachser, N (2003): Early social stress in female guinea pigs induces a masculinization of adult behavior and corresponding changes in brain and neuroendocrine function. Behavioural Brain Research 144: 199-210. Kaiser, S; Sachser, N (2001): Social stress during pregnancy and lactation affects in guinea pigs the male offsprings' endocrine status and infantilizes their behaviour. Psychoneuroendocrinology 26: 503-519. Kaiser, S; Brendel, H; Sachser, N (2000): Effects of ACTH applications during pregnancy on the female offsprings' endocrine status and behavior in guinea pigs. Physiology & Behaviour 70: 157-162. Kaiser, S; Sachser, N (1998): The social environment during pregnancy and lactation affects the female offsprings' endocrine status and behaviour in guinea pigs. Physiology & Behavior 63: 361-366. Kaiser, S; Sachser, N (1998): Die pränatale Beeinflussung von Verhalten und Physiologie bei Hausmeerschweinchen. In: Aktuelle Arbeiten zur artgemäßen Tierhaltung 1997. KTBL Schrift 380. Darmstadt: 164-172. Sachser, N; Kaiser, S (1996): Prenatal social stress masculinizes the females' behaviour in guinea pigs. Physiology & Behavior 60: 589-594. Kaiser, S; Sachser, N (1993): Effects of the social environment during pregnancy of guinea pigs on the behaviour of their female offspring. In: Nichelmann M et al. (ed.): Proceedings of the International Congress of Applied Ethology. Berlin: 396-398. Further publications regarding behavioural modulation during adolescence: Lürzel, S; Kaiser, S; Sachser, N (2010): Social interaction, testosterone, and stress responsiveness during adolescence. Physiology & Behavior 99: 40-46. Trillmich, F; Mueller, B; Kaiser, S; Krause, J (2009): Puberty in female cavies (Cavia aperea) is affected by photoperiod and social conditions. Physiology & Behavior 96: 476-480. Kaiser, S; Haderthauer, S; Sachser, N; Hennessy, MB (2007): Social Housing Conditions around Puberty Determine Later Changes in Plasma Cortisol Levels and Behavior. Physiology and Behavior 90: 405-411. Hennessy, MB; Hornschuh, G; Kaiser, S; Sachser, N (2006): Cortisol responses and social buffering: A study throughout the life span. Hormones and Behavior 49: 383-390. Sachser, N; Lick, C; Stanzel, K (1994): The environment, hormones and aggressive behaviour - a five-year-study in guinea pigs. Psychoneuroendocrinology 19: 697-707. Sachser, N (1993): The ability to arrange with conspecifics depends on social experiences around puberty. Physiology & Behavior 53: 539-544. Further publications regarding behavioural development: Glocker, ML; Langleben, DD; Ruparel, K; Loughead, JW; Gur, RC; Sachser, N (2009): Baby schema in infant faces induces cuteness perception and motivation for caretaking in adults. Ethology 115: 257-263. Glocker, ML; Langleben, DD; Ruparel, K; Loughead, JW; Valdez, JN; Griffin, MD; Sachser, N; Gur, RC (2009): Baby schema modulates the brain reward system in nulliparous women. Proceedings of the National Academie of Sciences of the USA. 106: 9115-9. Heiming, RS; Jansen, F; Lewejohann, L; Kaiser, S; Schmitt, A; Lesch, KP; Sachser, N (2009): Living in a dangerous world: the shaping of behavioral profile by early environment and 5-HTT genotype. Frontiers in Behavioral Neuroscience 3: 26. Hennessy, MB; Kaiser, S; Sachser, N (2009): Social buffering of the stress response: diversity, mechanisms, and functions. Frontiers in Neuroendocrinology 30(4): 470-82. Sachser, N (2009): Neugier, Spiel und Lernen: Verhaltensbiologische Anmerkungen zur Kindheit. In: Handbuch der Erziehungswissenschaft Band III/I Familie-Kindheit-Jugend-Gender: 329-339. Adrian, O; Dekomien, G; Epplen, JT; Sachser, N (2008): Body weight and rearing conditions of males, female choice and paternities in a small mammal, Cavia aperea. Ethology: 897-906. Hennessy, MB; Neisen, G; Bullinger, KL; Kaiser, S; Sachser, N (2006): Social organization predicts nature of infant-adult interactions in two species of wild guinea pigs (Cavia aperea and Galea monasteriensis). Journal of Comparative Psychology 120: 12-18. Adrian, O; Brockmann, I; Hohoff, C; Sachser, N (2005): Paternal behaviour in wild guinea pigs: A comparative study in three closely related species with different social and mating systems. Journal of Zoology (Lond.) 265: 97-105. Carter SC, Ahnert L, Grossmann K, Hrdy SB, Lamb ME, Porges SW, Sachser N (ed.) (2005): Attachment and Bonding: A New Synthesis. MIT Press, Cambridge. Pedersen, CA; Ahnert,L; Anzenberger, G; Belsky, J; Draper, P; Fleming, AS; Grossmann, K; Sachser, N; Sommer, S; Tietze, DP; Young, LJ (2005): Beyond infant attachment: the origins of bonding later in life. In: Carter SC, Ahnert L, Grossmann K, Hrdy SB, Lamb ME, Porges SW, Sachser N (ed.): Attachment and Bonding: A New Synthesis. MIT Press, Cambridge: 385-427. Touma, C; Ambrée, O; Görtz, N; Keyvani, K; Lewejohann, L; Palme, R; Paulus, W; Schwarze-Eicker, K; Sachser, N (2004): Age- and sex-dependent development of adrenocortical hyperactivity in a transgenic mouse model of Alzheimer's disease. Neurobiology of Aging 25: 893-904. Wewers, D; Kaiser, S; Sachser, N (2003): Maternal seperation in guinea pigs: a study in behavioural endocrinology. Ethology 109: 443-453.