Livestock guardian dogs – or “LGDs” – are commonly used by domestic sheep ranchers and reduce the need for killing wild carnivores to protect livestock. LGDs are mostly used in the United States to reduce the number of livestock killed by coyotes, but whether they can prevent killing by larger carnivores like wolves and grizzly bears is unclear. It is important to identify which behavioral traits and LGD breeds work best for guarding livestock so that ranchers can protect their stock and environmentalists can enjoy a greater number of wild animals on the landscape. This study investigated the effectiveness of different LGD breeds in the Western U.S. to help determine how best to use LGDs. I investigated (1) which LGD breed works best for each predator, (2) if LGD breeds behave differently, (3) how carnivores respond when LGDs and sheep move through their home ranges, and (4) whether having good LGDs makes ranchers more accepting of predators. I compared common U.S. breeds of LGD with three exotic breeds used primarily in other countries with wolves and grizzly bears. From 2013 – 2016 data was collected on sheep that were killed and what killed them, how different LGD breeds behaved, what carnivore species were present near sheep grazing with LGDs, and ranchers’ attitudes towards LGDs and large carnivores throughout Idaho, Montana, Oregon, Washington, and Wyoming. Results of the study show that all three of the exotic breeds of LGD are better at protecting sheep from certain predators than LGD breeds commonly used in the U.S. There are also some breed differences in LGD behavior that may help ranchers make better decisions about which LGD breed is best for them. Sheep grazing with LGDs seemed to drive-off wolves, but they also attracted smaller carnivores. Also, ranchers’ attitudes about LGDs are generally very positive, but they don’t affect attitudes about wolves and grizzly bears. Below, I discuss these and other findings in terms of both ecology and wildlife management.

Die wissenschaftliche Erforschung des Haushundes (Canis lupus forma familiaris) mit Fokus auf seine sozialen Eigenschaften hat große Relevanz in Anbetracht seiner zunehmenden Bedeutung im Zusammenleben mit dem Menschen als Familienmitglied und Arbeitstier. Ziel der vorliegenden Studie war es, die Relevanz von Dominanz in den Beziehungen von Gruppenmitgliedern einer Meute Englischer Foxhounds darzustellen sowie ihre Auswirkung auf die Sozialstruktur der Hunde. Weitergehend sollte die Analyse von aggressionsanzeigendem Verhalten und sozialen Strategien Aufschluss über Regelungsmechanismen im Zusammenleben der Hunde geben. Speichelcortisolanalysen sollten Einblick über die Stressexposition der Hunde in diesem Zusammenleben geben. Das Neutrophilen/ Lymphozyten Verhältnis im Blut sollte darüber hinaus mögliche Auswirkungen der Cortisolproduktion auf das Immunsystem aufzeigen. Für die Datenerhebung wurden 16 Englische Foxhounds einer Meute von 72 Hunden berücksichtigt. Je 4 Hündinnen und 4 Rüden wurden einer von 2 Gruppen zugeteilt. Über einen Zeitraum von 10 Monaten erfolgten Verhaltensbeobachtungen an jedem Individuum mittels der Methode Focal Animal Sampling. Von Hunden aus Gruppe 1 wurden 17,5 Stunden Beobachtungsmaterial und aus Gruppe 2 17,0 Stunden gesammelt. Die Speichelproben wurden mit der Salivette® der Firma SARSTEDT (Nümbrecht- Rommelsdorf) entnommen und mittels eines speziell für die Speichelcortisol- Analyse entwickelten Immunoassays (double- antibody biotin- linked enzyme immunoassay) analysiert. Ergebnisse: Die als möglicherweise dominanzanzeigend eingestuften Indikatoren, nämlich die Körperhaltung High Posture und die Durchsetzungskraft als Eigenschaft eines Hundes, konnten als solche nicht bestätigt werden. Es konnte keine dominanzbasierte Hierarchie ermittelt werden. Auch konnten von 82 Dyaden nur in 5 eine Dominanz- Subordinanz- Beziehung ermittelt werden, was kein aussagekräftiges Ergebnis darstellt. Aggressive Handlungen wurden in beiden Gruppen pro Stunde durchschnittlich jeweils 12 Mal beobachtet, jedoch meist in der Intensität 1 - 2 (von 5- stufiger Skala). Sie wurden hochsignifikant häufiger unter Rüden als unter Hündinnen beobachtet (p= 0,002). Berechnungen der Aggressionskoeffizienten belegten deutliche Unterschiede in den individuellen Aggressionsniveaus. Die Analyse ausgetragener Konflikte auf Taktiken und Strategien lieferte jedoch keine signifikanten Ergebnisse. Die Foxhounds reagierten situativ und selten gegner- und nie kontextabhängig. Die Speichelcortisolanalysen belegten vielfach höhere Basal- Mittelwerte der Foxhounds verglichen mit Analysen von Hunden anderer Studien. Eine Reduktion des Cortisolwerts erfolgte bei 14 von 16 Hunden nach 20- minütigem Einzelspaziergang mit Menschenkontakt. Allerdings konnte keine Verbindung zwischen dem Speichelcortisolwert und dem soziometrisch errechneten Rangplatz in der Gruppe ermittelt werden. Ebenso bestand keine Korrelation zwischen dem Speichelcortisolwert und Immunstatus sowie Aggressionspotential. Schlussfolgerungen: Dominanz spielte keine erkennbare Rolle in den sozialen Interaktionen und Beziehungen der Hunde. Die Ergebnisse lassen die Schlussfolgerung auf eine egalitäre Sozialstruktur der Foxhounds zu statt einer dominanzabhängigen, was auch durch die situativ geregelten Begegnungen unterstützt wird. Aggressives Verhalten als häufig repräsentiertes Kommunikationselement wurde bei den einzelnen Hunden unterschiedlich oft beobachtet, was auf die Verschiedenheit der Charaktere und ihre Motivationen, Konflikte einzugehen, hindeutet. Die häufiger unter Rüden beobachtete Aggression kann auf ein erhöhtes Konkurrenzpotential hindeuten. Die im Speichel der Foxhounds gemessenen Cortisolwerte lassen die Vermutung auf eine durch das Gruppenleben bedingte Erhöhung des Basalwerts zu, ohne Konsequenzen auf den Immunstatus. Die fehlenden Korrelationen zu den individuellen Rangplätzen und Aggression unterstützt die Vermutung eines lockeren bzw. egalitären Sozialgefüges.

Die wissenschaftliche Erforschung des Haushundes (Canis lupus forma familiaris) mit Fokus auf seine sozialen Eigenschaften hat große Relevanz in Anbetracht seiner zunehmenden Bedeutung im Zusammenleben mit dem Menschen als Familienmitglied und Arbeitstier. Ziel der vorliegenden Studie war es, die Relevanz von Dominanz in den Beziehungen von Gruppenmitgliedern einer Meute Englischer Foxhounds darzustellen sowie ihre Auswirkung auf die Sozialstruktur der Hunde. Weitergehend sollte die Analyse von aggressionsanzeigendem Verhalten und sozialen Strategien Aufschluss über Regelungsmechanismen im Zusammenleben der Hunde geben. Speichelcortisolanalysen sollten Einblick über die Stressexposition der Hunde in diesem Zusammenleben geben. Das Neutrophilen/ Lymphozyten Verhältnis im Blut sollte darüber hinaus mögliche Auswirkungen der Cortisolproduktion auf das Immunsystem aufzeigen. Für die Datenerhebung wurden 16 Englische Foxhounds einer Meute von 72 Hunden berücksichtigt. Je 4 Hündinnen und 4 Rüden wurden einer von 2 Gruppen zugeteilt. Über einen Zeitraum von 10 Monaten erfolgten Verhaltensbeobachtungen an jedem Individuum mittels der Methode Focal Animal Sampling. Von Hunden aus Gruppe 1 wurden 17,5 Stunden Beobachtungsmaterial und aus Gruppe 2 17,0 Stunden gesammelt. Die Speichelproben wurden mit der Salivette® der Firma SARSTEDT (Nümbrecht- Rommelsdorf) entnommen und mittels eines speziell für die Speichelcortisol- Analyse entwickelten Immunoassays (double- antibody biotin- linked enzyme immunoassay) analysiert. Ergebnisse: Die als möglicherweise dominanzanzeigend eingestuften Indikatoren, nämlich die Körperhaltung High Posture und die Durchsetzungskraft als Eigenschaft eines Hundes, konnten als solche nicht bestätigt werden. Es konnte keine dominanzbasierte Hierarchie ermittelt werden. Auch konnten von 82 Dyaden nur in 5 eine Dominanz- Subordinanz- Beziehung ermittelt werden, was kein aussagekräftiges Ergebnis darstellt. Aggressive Handlungen wurden in beiden Gruppen pro Stunde durchschnittlich jeweils 12 Mal beobachtet, jedoch meist in der Intensität 1 - 2 (von 5- stufiger Skala). Sie wurden hochsignifikant häufiger unter Rüden als unter Hündinnen beobachtet (p= 0,002). Berechnungen der Aggressionskoeffizienten belegten deutliche Unterschiede in den individuellen Aggressionsniveaus. Die Analyse ausgetragener Konflikte auf Taktiken und Strategien lieferte jedoch keine signifikanten Ergebnisse. Die Foxhounds reagierten situativ und selten gegner- und nie kontextabhängig. Die Speichelcortisolanalysen belegten vielfach höhere Basal- Mittelwerte der Foxhounds verglichen mit Analysen von Hunden anderer Studien. Eine Reduktion des Cortisolwerts erfolgte bei 14 von 16 Hunden nach 20- minütigem Einzelspaziergang mit Menschenkontakt. Allerdings konnte keine Verbindung zwischen dem Speichelcortisolwert und dem soziometrisch errechneten Rangplatz in der Gruppe ermittelt werden. Ebenso bestand keine Korrelation zwischen dem Speichelcortisolwert und Immunstatus sowie Aggressionspotential. Schlussfolgerungen: Dominanz spielte keine erkennbare Rolle in den sozialen Interaktionen und Beziehungen der Hunde. Die Ergebnisse lassen die Schlussfolgerung auf eine egalitäre Sozialstruktur der Foxhounds zu statt einer dominanzabhängigen, was auch durch die situativ geregelten Begegnungen unterstützt wird. Aggressives Verhalten als häufig repräsentiertes Kommunikationselement wurde bei den einzelnen Hunden unterschiedlich oft beobachtet, was auf die Verschiedenheit der Charaktere und ihre Motivationen, Konflikte einzugehen, hindeutet. Die häufiger unter Rüden beobachtete Aggression kann auf ein erhöhtes Konkurrenzpotential hindeuten. Die im Speichel der Foxhounds gemessenen Cortisolwerte lassen die Vermutung auf eine durch das Gruppenleben bedingte Erhöhung des Basalwerts zu, ohne Konsequenzen auf den Immunstatus. Die fehlenden Korrelationen zu den individuellen Rangplätzen und Aggression unterstützt die Vermutung eines lockeren bzw. egalitären Sozialgefüges.

<p>The genetic basis for behavioural traits is largely unknown. The overall aim of this thesis was to find genes with importance for behavioural traits related to fear and anxiety. Microarray analysis was used to screen expression profiles of brain regions important for emotional behaviour in dogs, wolves, foxes and mice. In a first experiment, dogs and their wild ancestors the wolves were compared. Our results suggested that directed selection for behaviour might have resulted in expression changes in few genes acting on several brain functions, possibly affecting behaviour. However, the observed expressional differences were confounded with environmental effects. This was addressed in a second study on domesticated silver foxes. By correlating behaviour and brain gene expression in foxes selected for tameness to non-selected foxes raised in the same environment, we found large behavioural differences but only few genes with differential expression in the brain. Fifteen of the 40 genes showing evidence of expression difference were related to haem or haemoglobins. Further studies showed an additive genetic effect on brain gene expression, similar to the additive genetic inheritance of behaviour, indicating an involvement in domestication. Transcriptional profiling was also used for finding genes involved with the sleep disorder narcolepsy. Narcoleptic Doberman pinschers homozygous for the canarc-1 mutation were compared to their unaffected heterozygots revealing reduced expression of three genes, TAC1, PENK and SOCS2, with relevance to the narcoleptic phenotype. Finally gene expression was investigated in relation to anxiety-related traits in a mouse model. Surprisingly, as in the fox study, genes coding for haemoglobins indicated differential expression in the brain between animals with different anxiety levels. Our combined results suggest that genes like haemoglobins, best known for their function in oxygen transport in blood, may also participate in brain functions related to decreased anxiety in domestic animals. </p>

The genetic basis for behavioural traits is largely unknown. The overall aim of this thesis was to find genes with importance for behavioural traits related to fear and anxiety. Microarray analysis was used to screen expression profiles of brain regions important for emotional behaviour in dogs, wolves, foxes and mice. In a first experiment, dogs and their wild ancestors the wolves were compared. Our results suggested that directed selection for behaviour might have resulted in expression changes in few genes acting on several brain functions, possibly affecting behaviour. However, the observed expressional differences were confounded with environmental effects. This was addressed in a second study on domesticated silver foxes. By correlating behaviour and brain gene expression in foxes selected for tameness to non-selected foxes raised in the same environment, we found large behavioural differences but only few genes with differential expression in the brain. Fifteen of the 40 genes showing evidence of expression difference were related to haem or haemoglobins. Further studies showed an additive genetic effect on brain gene expression, similar to the additive genetic inheritance of behaviour, indicating an involvement in domestication. Transcriptional profiling was also used for finding genes involved with the sleep disorder narcolepsy. Narcoleptic Doberman pinschers homozygous for the canarc-1 mutation were compared to their unaffected heterozygots revealing reduced expression of three genes, TAC1, PENK and SOCS2, with relevance to the narcoleptic phenotype. Finally gene expression was investigated in relation to anxiety-related traits in a mouse model. Surprisingly, as in the fox study, genes coding for haemoglobins indicated differential expression in the brain between animals with different anxiety levels. Our combined results suggest that genes like haemoglobins, best known for their function in oxygen transport in blood, may also participate in brain functions related to decreased anxiety in domestic animals.

Made available in DSpace on 2016-04-28T20:16:20Z (GMT). No. of bitstreams: 1 2006-Simone Pontes Xavier Salles.pdf: 555957 bytes, checksum: 0138f22503bfb564545e246c2df55286 (MD5) Previous issue date: 2006-02-21 / The aim of this study was to know the profile of sanitary conditions of domiciliated dogs in Campus of UFRRJ with emphasis in associated factors of prevalence of enteric parasites. In the period of February to December of 2003, houses that had dogs were visited and their owners were interviewed. Two hundred fifteen dogs were examinated and their faeces collected. The centrifuge-flotation technique in saturate sugar solution was used to feacal exames. Variables such as faeces elimination, hygiene of ambient, access to the street, anthelmintic treatment, feed and presence of ectoparasites were analyzed as possible associated factors of prevalence of enteric parasites. With c2 were tested the possible association of the variables, using the program EPIINFO 2002. The prevalence of enteric parasites in the Campus was 56.7%. The Ancylostomatidae were more prevalent (40%), followed by Ascarididae (15.81%), Trichuris vulpis (8.37%), Cystoisospora sp. (17%), Dipylidium caninum (6.97%) and Giardia sp. (2.32%). Mixed intestinal infections were also observed in 48 animals. Characteristics as sex and breed weren?t associated to the enteric parasite infections. One to 3 year dogs showed the highest prevalence of Ancylostomatidae, emphasing the importance of prophylaxis of helminths in this age-range. Access to the street was associated to higher prevalence of enteric parasite infection, probably by the contact with contaminated ambient or by the deficient care of their owners. Animals on the age of 1 to 3 years showed more prevalence of Ancilostom?deos infection, verifying the importance of a prophylaxis on the control of these helmints on this age. The sanitary conditions of dogs were satisfactory, specially in relation to hygiene of the ambient where they lived. / O objetivo deste trabalho foi conhecer o perfil sanit?rio de c?es domiciliados no Campus da UFRRJ, com ?nfase na preval?ncia de parasitosintestinais e fatores associados. No per?odo de fevereiro a dezembro de 2003 foram visitados os domic?lios que tinham c?es e realizada uma entrevista estruturada aos propriet?rios. Foram coletadas amostras de fezes de 215 animais, e para o exame coprol?gico foi utilizada a t?cnica de centr?fugo-flutua??o em solu??o saturada de a??car. Vari?veis como elimina??o das fezes, higiene do ambiente, acesso ? rua, tratamento anti- helm?ntico, alimenta??o e presen?a de ectoparasitos foram analisadas como poss?veis fatores associados ? preval?ncia de endoparasitos. Realizou-se o teste de associa??o das vari?veis pelo c2 com uso do programa EPIINFO 2002. A preval?ncia de parasitos intestinais no Campus Universit?rio foi 56,7%. Os Ancilostom?deos foram mais prevalecentes (40%), seguidos por Ascarid?deos (15,81%), Trichuris vulpis (8,37%), Cystoisospora sp. (17%), Dipylidium caninum (6,97%) e Giardia sp.(2,32%). Infec??es intestinais mistas tamb?m foram encontradas em 48 animais. Caracter?sticas como sexo e ra?a n?o favoreceram a infec??o por enteroparasitos, no entanto animais com idade entre 1 e 3 anos apresentaram maior preval?ncia de infec??o por Ancilostom?deos, retratando a import?ncia de uma profilaxia no controle das helmintoses nesta faixa et?ria. Acesso ? rua esteve associado ? maior preval?ncia de infec??o por parasitos intestinais, provavelmente devido a maior exposi??o a ambientes contaminados ou at? por serem menos tratados por seus propriet?rios. As condi??es sanit?rias dos animais foram satisfat?rias, principalmente em rela??o ao quesito higiene do ambiente onde eles viviam.

The dog was the first animal to be domesticated and the process started at least 15 000 years ago. Today it is the most morphologically diverse mammal, with a huge variation in size and shape. Dogs have always been useful to humans in several ways, from being a food source, hunting companion, guard, social companion and lately also a model for scientific research. This thesis describes some of the changes that have occurred in the dog’s genome, both during the domestication process and later through breed creation. To give a more comprehensive view, three genetic systems were studied: maternally inherited mitochondrial DNA, paternally inherited Y chromosome and biparental autosomal chromosomes. I also sequenced complete mitochondrial genomes to view the effect new living conditions might have had on dogs’ genes after domestication. Finally, knowledge of the genetic structure in purebred dogs was used to test analytic methods usable in other species or in natural populations where little information is available. The domestication process appears to have caused a relaxation of the selective constraint in the mitochondrial genome, leading to a faster rate of accumulation of nonsynonymous changes in the mitochondrial genes. Later, the process of breed creation resulted in genetically separated breed groups. Breeds are a result from an unequal contribution of males and females with only a few popular sires contributing and a larger amount of dams. However, modern breeder preferences might lead to disruptive selective forces within breeds, which can result in additional fragmentation of breeds. The increase in linkage disequilibrium that this represents increases the value of purebred dogs as model organisms for the identification and mapping of diseases and traits. Purebred dogs’ potential for these kinds of studies will probably increase the more we know about the dog’s genome.

Polymorphism in coding regions and regions controlling gene expression is the major determinant of adaptive differences in natural populations. Genes of the major histocompatibility complex (MHC) possess a high level of genetic variation, which is maintained by selection over long coalescence times. MHC genes encode antigen-presenting molecules in the adaptive immune system, which protects the host from infectious diseases. However, MHC molecules may also present self-peptides and for most autoimmune diseases there is a genetic factor associated with the MHC. MHC genes have been used to learn about the interplay of selection and historical population events. In domestic dogs and their progenitor, the wolf, I explored factors associated with domestication and breed formation and their influence not only on MHC coding regions but also on the haplotypic structure of the class II region. Polymorphism and strong selection was demonstrated in the proximal promoters of MHC genes in dogs and wolves. Hence, genetic variation associated with MHC gene expression may have at least equal importance for a well functioning immune system. Associations between promoter sequences and particular coding alleles suggested allele-specific expression patterns. SNP haplotypes of the MHC class II region revealed ancestral as well as convergent haplotypes, in which combinations of alleles are kept by selection. Interestingly, weaker allelic associations were found between different genes and between coding regions and promoters in dogs compared to wolves. Potentially, this could cause insufficient defense against infections and predispose dogs to autoimmune diseases. For example, I identified a site in the promoter region that showed a consistent difference between haplotypes conferring susceptibility and protection to diabetes in dogs, which should be investigated further. Furthermore, I investigated how selection and demographic changes associated with glacial and inter-glacial periods have affected MHC variation in European hedgehogs and extended the prevailing knowledge concerning their population history.

Submitted by (edna.saturno@ufrpe.br) on 2016-07-18T15:45:44Z No. of bitstreams: 1 Adriana Katia da Rocha Neves.pdf: 642559 bytes, checksum: 6e769e8fbed7f307d302b2c25dae6abb (MD5) / Made available in DSpace on 2016-07-18T15:45:44Z (GMT). No. of bitstreams: 1 Adriana Katia da Rocha Neves.pdf: 642559 bytes, checksum: 6e769e8fbed7f307d302b2c25dae6abb (MD5) Previous issue date: 2014-02-18 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The overpopulation of dogs in urban areas causes serious problems to public health and animal welfare. Alternative methods of contraception have been widely discussed, but there is still controversy regarding the painful effects of sclerosing agents. This study aimed to characterize the degree of discomfort caused by chemical castration by zinc gluconate intratesticular injection and compare it with the conventional procedure of orchiectomy, taking into consideration both behavioral and biochemical parameters, and also to evaluate the degree of sensitivity of such parameters. This study was conducted in the city of Recife, Brazil, between April and December 2013. Nineteen male dogs were randomly divided into three groups: G1 (control – subjected to anesthesia only), G2 (orchiectomy) and G3 (zinc gluconate intratesticular injection). The evaluations were performed at five different moments ( M0 , M1 , M2 , M3 and M4 ) , in which were evaluated plasma cortisol , serum glucose , stress leukogram ( neutrophils / lymphocyte ) and pain level according to the Melbourne Scale. No significant differences in the concentrations of cortisol and leukocyte count were found. The degree of discomfort was higher in G2, despite not exceeding the mild pain score according to the Melbourne Scale. Serum glucose concentration was statistically higher in G3 compared with G2, even though both were similar to the control group. In face of the results it was concluded that chemical sterilization causes similar discomfort to that generated by orchiectomy procedure and can be used as a routine procedure in the control of fertility in dogs. / A superpopulação de cães nos centros urbanos ocasiona sérios problemas de saúde pública e bem-estar animal. Métodos alternativos de contracepção têm sido bastante discutidos, mas ainda existe polêmica no que diz respeito ao efeito álgico dos agentes esclerosantes. Este trabalho teve o propósito de caracterizar o grau de desconforto causado pela castração química por meio da injeção intratesticular de gluconato de zinco e comparar com o procedimento convencional da orquiectomia, levando-se em consideração parâmetros comportamentais e bioquímicos, além de avaliar o grau de sensibilidade de tais parâmetros. O presente estudo foi conduzido na cidade do Recife, Brasil, entre os meses de abril a dezembro de 2013. Dezenove cães machos foram distribuídos aleatoriamente em três grupos: G1 (controle – submetidos apenas à procedimento anestésico), G2 (orquiectomia) e G3 (injeção intratesticular de gluconato de zinco). As avaliações foram realizadas em cinco diferentes momentos (M0, M1, M2, M3 e M4), onde foram avaliados cortisol plasmático, glicose sérica, leucograma de estresse (neutrófilos/linfócitos) e grau de desconforto por meio da Escala de Melbourne. Não foram encontradas diferenças significativas nas concentrações de cortisol e contagem de leucócitos. O grau de desconforto foi maior no G2, apesar de não ultrapassar o escore de dor leve segundo a Escala de Melbourne. A concentração sérica de glicose foi estatisticamente maior no G3 quando comparada com o G2, embora ambos tenham sido semelhantes ao grupo controle. Diante dos resultados concluiu-se que a esterilização química causa um desconforto similar àquele gerado pelo procedimento de orquiectomia, podendo ser utilizado como procedimento de rotina no controle da fertilidade de cães.

Abstract Hosts and pathogens are involved in a continuous evolutionary arms race, where pathogens attack and hosts defend themselves. The main tools for winning the race are natural selection and the genetic diversity that selection acts on. However, in small populations natural selection may be ineffective. Therefore, the genes taking part in immune defense may lack adaptability to new or changing pathogens. Major histocompatibility complex (MHC) is an important genomic region that includes highly polymorphic immune defense genes. In this doctoral thesis, I studied the natural selection and genetic diversity of MHC class II genes in dogs and Finnish wolves. I also used dog MHC diversity to estimate the number of founding wolves in dog domestication. The Finnish wolf population declined rapidly in size due to excessive hunting from the late 19th century until the early 20th century. After decades of a very small population size, the population started recovering in the mid-1990s. This study shows that, despite the fluctuations in population size, the diversity of the MHC loci in the Finnish wolf has remained high and comparable to the larger neighboring Russian Karelian wolf population. Unlike the neutral genetic markers, the MHC loci of the Finnish and Russian Karelian populations have not differentiated. These results indicate similar balancing selection acting on the MHC loci of the two wolf populations. In dogs, the strength of natural selection is likely weakened by artificial selection and veterinary care. The potential phases of natural selection would be during embryogenesis and fetal development. However, no strong signs of prenatal selection were found in this study. MHC diversity was estimated to be higher in Asian dogs than in dogs from Europe. A simulation study indicated a minimum of 500 founding wolves for the modern dog population. Dog MHC diversity implies an Asian origin for domestication from a large and diverse wolf population. Both natural selection and demography have an influence on the genetic diversity of a species. In small populations, random genetic drift is enforced. However, in loci with important fitness impacts, selection may be particularly strong and outweigh drift, as demonstrated in the MHC loci of a small wolf population in this study. / Tiivistelmä Isäntä ja taudinaiheuttajat käyvät jatkuvaa kaksinkamppailua, jossa taudinaiheuttajat hyökkäävät ja isäntä puolustautuu. Kamppailussa menestymiseen tarvitaan geneettistä monimuotoisuutta sekä sen pohjalta toimivaa luonnonvalintaa. Pienissä populaatioissa luonnonvalinnan teho voi kuitenkin heikentyä, jolloin immuunipuolustukseen osallistuvat geenit eivät kykene sopeutumaan uusiin tai muuttuneisiin taudinaiheuttajiin. MHC-alueella (major histocompatibility complex) sijaitsee suuri joukko monimuotoisia immuunipuolustukseen osallistuvia geenejä. Väitöskirjassani tutkin luokan II MHC-geeneihin kohdistuvaa luonnonvalintaa ja niiden geneettistä monimuotoisuutta koirilla ja Suomen susilla. Arvioin myös koiran kesyttämisprosessiin osallistuneiden susien määrää nykykoiran MHC-monimuotoisuuden pohjalta. Suomen susipopulaation koko pieneni nopeasti voimakkaan metsästyksen vuoksi 1800-luvun lopulta 1900-luvun alkuun. Populaatio pysyi hyvin pienenä useita vuosikymmeniä, kunnes se alkoi elpyä 1990-luvun puolivälissä. Tutkimus osoitti, että populaatiokoon vaihteluista huolimatta Suomen susien MHC-geenien monimuotoisuus on säilynyt korkeana ja on vastaavalla tasolla kuin Venäjän Karjalan susipopulaatiossa. Suomen ja Venäjän Karjalan susipopulaatioiden MHC-geenit eivät ole erilaistuneet, vaikka populaatiot poikkeavat toisistaan neutraalien geenimerkkien suhteen. Samanlainen tasapainottava valinta näyttäisi kohdistuvan näiden susipopulaatioiden MHC-geeneihin. Keinotekoinen valinta ja eläinlääketieteellinen hoito todennäköisesti heikentävät koirien MHC-geeneihin kohdistuvaa luonnonvalintaa. Luonnonvalinta voisi yhä vaikuttaa alkion- ja sikiönkehityksen aikana, mutta tästä ei tutkimuksessa löytynyt todisteita. MHC-muuntelun määrän arvioitiin olevan suurempaa aasialaisissa kuin eurooppalaisissa koirissa. Simulaatiotutkimuksen mukaan nykyisen koirapopulaation perustamiseen olisi tarvittu vähintään 500 sutta. Tulokset viittaavat koiran kesyttämisen tapahtuneen Aasiassa suuresta ja monimuotoisesta susipopulaatiosta. Sekä luonnonvalinta että demografia vaikuttavat lajien geneettiseen monimuotoisuuteen. Pienissä populaatioissa satunnaisajautuminen voimistuu. Valinta voi kuitenkin olla erityisen voimakasta ja voittaa satunnaisajautumisen geeneissä, joilla on erityisen tärkeä vaikutus yksilön kelpoisuuteen, kuten tutkimuksessa osoitettiin pienen susipopulaation MHC-geenien kohdalla.