Parasitism can be defined as a biological interaction in which one party benefits at the expense of another (Keeton and Gould 1986). However unlike predation, the parasite does not kill its host. In the case of avian brood parasitism, one bird lays its eggs in the nest of a member of its own or another species and then abandons its offspring to the care of its new foster parents. These foster parents or 'hosts' then raise the parasitic young at the expense of their own brood. Brood parasitic birds have reproductive advantages over those which provide parental care for their young because: 1) parental care provided by several fosterers allows a female to produce more successful offspring than she is capable of rearing herself in one season, and 2) parasite offspring are usually distributed among many host nests thereby increasing the probability that at least some offspring will escape predation (Payne 1977). Obligate interspecific brood parasitism, where females only parasitize the nests of other species, is a reproductive strategy adopted by approximately 1% of all bird species and is practiced by members of five families (Anatidae, Cuculidae, Indicatoridae, Icteridae, and Ploceidae). The degree to which interspecific brood parasites reduce host nesting success varies with the reproductive tactics of the parasite. For example, Common Cuckoo chicks (Cuculus canorus) eject eggs and young nest mates from the host nest with the help of an instinctive urge to push out of the nest anything that touches the sensitive shallow depression in the parasitic nestling's back (Lack 1968). Young African Greater Honey-guides (Indicator indicator) stab host nestlings to death with special mandibular hooks that drop off after two weeks of age (Friedmann 1955). In contrast, black-headed duck hatchlings seek only protection and warmth for 1-2 days post hatching and then leave the nest with no further cost to their host (Weller 1968). Finally, Brown-headed Cowbird nestlings intermediately affect host reproductive success by diverting parental resources such as food away from the host's young (Payne 1977). This loss of host fitness results in selective pressure for host defenses against parasitism such as egg ejection (Neudorf and Sealy 1992), clutch abandonment (Burgham and Picman 1989), or increased nest defense early in the nesting cycle (Burgham and Picman 1989, Briskie and Sealy 1989, Neudorfand Sealy 1992). To circumvent these host responses, adaptation in brood parasites has resulted in selective pressure for egg mimicry (Rothstein 1990), egg removal, or shorter incubation periods (Briskie and Sealy 1990, Payne 1977). The Brown-headed Cowbird is the most abundant and widely distributed obligate interspecific brood parasite in North America. Although the breeding behaviour of this bird has been widely studied, most findings are contradictory. The mating system of the Brown-headed cowbird has been described as ranging from monogamous (Laskey 1950, Dufty 1982a, 1982b, Yokel 1986), to promiscuous (Elliot 1980). Most studies also suggest that cowbirds parasitize multiple host species (Friedmann 1929, p 177-188, Jones 1941, McGeen & McGeen 1968, Elliot 1977, Fleischer 1985). However, a few suggest that some individuals may be host specialists (Walkinshaw 1949, McGeen & McGeen 1968). Few of these studies have used genetic techniques to determine the actual mating patterns and to investigate the breeding biology of males and females in a single marked population. The main objective of this study was to use molecular genetic DNA markers as well as behavioural observation to study the mating system and host specificity of a Brown-headed Cowbird population at Delta Marsh, Manitoba. More specifically, my objectives were to: 1) determine whether DNA microsatellite markers are useful for determining parentage in Brown-headed Cowbird populations 2) document the genetic mating system and the patterns of host use by individual females in a population of resident cowbirds. My findings provide the first evidence that microsatellites are useful for high resolution parentage analyses in brood parasitic bird species where there is no A priori information available on male or female parentage. In addition, they are the first to directly quantity the mating system of a Brown-headed Cowbird population and to suggest that individual females are best described as host generalists but may be showing some preference for host nests in one habitat over another. / Thesis / Master of Science (MSc)

No description available.

No description available.

Although sexual selection in nature has been studied intensively, much is still unknown about the evolution of mating systems in wild populations: for example, how male competition and female choice interact, or the effect of environmental heterogeneity on selection. Further, important questions remain about the consequences of sexual selection for genetic structuring and genetic variation within populations. In this thesis, I investigate the causes and consequences of sexual selection in a polygynous mammal, the red deer Cervus elaphus. This species is characterized by high male reproductive skew resulting from competition to defend harems of females. Here however, I present evidence for previously unappreciated complexity in the mating system, in terms of female mating behaviour and environmental influences on male-male competition. I then go on to investigate the consequences of non-random mating on co-ancestry and inbreeding in the population. Finally, I investigate methods for separating genetic and environmental sources of covariance between individuals. Specifically, I: (i) Show a surprising degree of female mobility during the breeding season (the 'rut‘). Around 40% of females change harem when in oestrus and almost half of these movements result in paternity for the novel male; however I show that these movements are unlikely to be explained by female choice for mates. (ii) Reveal that variance in male mating success is affected by variation in ecological parameters, in particular the interaction between the number of immigrant males in the rutting population and the temporal synchrony of females. (iii) Demonstrate substantial inter-individual differences in the plasticity of acoustic signals produced by rutting males with changes in social context. (iv) Reveal the existence in this population of three rarely reported mating behaviours in polygynous mammals. I find around a fifth of females mate with the same male in multiple years; female relatives frequently mate with the same male; and males rut in locations close to their relatives. Further, I show these behaviours are associated with higher co-ancestry and inbreeding in the population than expected under random mating. (v) Finally, I investigate how spatial associations between relatives upwardly bias estimates of heritability in four phenotypic traits. I do this by accounting for shared environment effects in animal models by i) inclusion of spatial autocorrelation parameters and ii) a novel multi-matrix approach.

Pre-copulatory sexual cannibalism (pre-SC), or predation of a potential mate before sperm transfer, provides an ideal model system for behavioral ecology's current focus on inter-sexual conflict. Studying the North American fishing spider (Dolomedes triton), I tested three female-benefit hypotheses for pre-SC: indirect benefits, direct benefits, and aggressive spillover. First, pre-SC may reflect a mating bias providing females with 'good-genes' benefits. By manipulating each female's options with regard to the most cited phenotypic advantage in male spiders, body size, I show that while females exhibit no bias in their attack tendency on males of different body sizes, large males mate significantly more often than small males. Second, pre-SC may be explained by direct benefits if females use it as an adaptive foraging/mating trade-off. My work provides mixed support for this idea: (i) females vary attacks according to the availability of mates, (ii) females do not vary attacks according to the availability of food, and (iii) females derive discrete fecundity benefits from consuming a male. Finally, I tested the aggressive-spillover hypothesis, which posits that pre-SC is a by-product of selection for high levels of aggression towards prey in traditional foraging contexts. Path analysis indicated intra-individual, positive correlations between aggression in foraging contexts and the mating context, thus supporting the hypothesis. I conclude by stressing that pre-SC in a given species may rarely be explained by one hypothesis, and that studies accounting for multiple benefits that fluctuate as behavioral-ecological contexts shift should give a more realistic glimpse of behavioral ecology and evolution.

No description available.

No description available.

Polygyny is the most common mating system in mammalian species (95%), yet our understanding of polygynous systems and microevolutionary processes is still limited. Pinniped mating systems range from extreme polygyny (e.g. elephant seals) to sequential female defence by males and hence have often been used as models for mating system studies. Parentage analysis has enabled the examination of mating success, the identification of pedigrees, and the elucidation of social organisation, greatly enhancing our understanding of mating systems (Chapter 1). However, such analyses are not without pitfalls, with erroneous assignments common in open systems (i.e. when parental and offspring samplings are incomplete). We investigated the effects of the user-defined parameters on the accuracy of parental assignment using two commonly used parental allocation programme, CERVUS and PASOS (Chapter 2). We showed that inaccurate user-defined parameters in CERVUS and PASOS can lead to highly biased output e.g. the assignment rate at 95% CL of offspring with a sampled known mother to sampled males decreased from 58% to 32% when the proportion of candidate males sampled in the parameter options decreasing 4-fold. We found that the use of both CERVUS and PASOS for parentage assignment can increase the likelihood of correctly allocating offspring to sampled parents to 97% in our study system. Incorrect parental assignment can bias estimates of various biological parameters, such as lifetime reproductive success and mate choice preference, and hence bias ecological and evolutionary interpretations. Here, we propose solutions to increase the power of parentage assignment and hence decrease the bias in biological parameter estimates. In addition, we analysed the effects of the intrinsic bias in likelihood assignment approaches towards assigning higher probability of parentage on individuals with rare alleles and those with heightened offspring-parent matches, which increase with the number of homozygous loci (Chapter 3). We showed that, as a consequence of the algorithms employed in the programmes CERVUS and PASOS, heterozygote males with rare genotypes are assigned higher rates of parentage than males with common alleles. Consequently, where two males could both be biological fathers of a given offspring, parentage assignment will more often go to the male with the rarer alleles (most often in heterozygous loci). Thus, the commonly used parentage assignment methods may systematically bias the results of parentage analyses towards supporting the notion that females prefer more genetically unusual, most often heterozygous, males. Such a bias may sway investigators towards incorrectly supporting the concept that females choose genetically more unusual males for heterozygosity fitness benefits that underpin the good genes hypothesis, when in fact no such relationship may exist. In polygynous mammals, successful males mate with multiple females by competing with and limiting the access of other males to females. When the status of many males (age, size, health, genetic etc.) prevents them from achieving the primary mating tactic, theory predicts selection for a diversification of male mating tactics. Recent studies in pinnipeds have shown that observed male mating success was correlated to male paternity success in some species (elephant-seals), but not in others (grey seals). The existence of alternative mating strategies can explain those discrepancies. Chapter 4 implemented the guidelines provided in Chapter 2 and 3 and focused on the polygynous New Zealand fur seal Arctocephalus forsteri, predicting that 1) competition for females is likely to cause a diversification of male mating tactics; and 2) that alternative tactics can yield reproductive success. Our results indicated three male behavioural profiles; one corresponded to large territorial males and two illustrated a continuum of alternative tactics employed by non-territorial subordinate males. Our study highlights that holding a territory is not a necessary condition for reproductive success in a population of otariids. The degree of sexual size dimorphism in polygynous species is expected to increase with the degree of intra-sexual competition and in turn with the degree of polygyny. The life history of an individual is the pattern of resource allocations to growth, maintenance, and reproduction throughout its lifetime. Both females and males incur viability costs of mating and reproduction. However, male viability costs due to increase growth and male-male competition can be greater than female viability costs of mate choice and reproduction. Although an abundant literature on sexual dimorphism in morphology, physiology, and parasite infections is available, little is known on the intra-sexual differences in physiology and parasite infections associated to the reproductive success of different mating strategies in mammalian species. Chapter 5 examined the reproductive costs between territorial and subordinate males New Zealand fur seal related to their relative reproductive success using a multidisciplinary approach (behaviour, genetics, endocrinology, parasitology). We found that dominant New Zealand fur seal males endure higher reproductive costs due to the direct and indirect effects of high testosterone levels and parasite burdens. Our study highlights that holding a territory confers a higher reproductive success, but induces higher costs of reproduction that may impair survival. Understanding microevolutionary processes associated to polygynous systems is fundamental in light of the ongoing anthropogenic alteration of the environment through climatic variations and habitat reduction which ultimately affect opportunity for sexual selection and shape the life history trade-offs.

Species of Valerianaceae in South America represent one of the best examples of rapid diversification on a continental scale. The phylogeny of Valerianaceae has received a lot of attention within the last 10 years, but relationships among the South American species are fairly unresolved. Results from previous studies have not been well resolved with traditional genetic markers, most likely due to its recent and rapid radiation. Species in this clade exhibit a variety mating systems and inflorescence types. For the first part of this research I used several traditional plastid markers, and 3 new low copy nuclear markers to better resolve the phylogeny and then explore mating system evolution within the clade. For the second part of this research I collected high-throughput “next-generation” genomic sequence data from reduced representation libraries obtained using genotyping-by-sequencing (GBS) protocols, along with several phylogenetic methods, to try to further resolve the phylogeny of this group.

Estudos relacionados ao sistema de acasalamento nos insetos permite a compreensão dos aspectos evolutivos do comportamento reprodutivo de uma espécie. Esses sistemas são classificados, geralmente, pelo número de parceiros sexuais de um indivíduo durante um período de acasalamento. Em fêmeas, pode ocorrer monogamia, quando a cópula for realizada com somente um macho e, poliandria, quando há ocorrência de múltiplas cópulas com machos diferentes ou com o mesmo macho (cópulas repetidas). Em espécies como a broca-do-café, Hypothenemus hampei, que passam a maior parte de sua vida (ovo a adulto) no interior do fruto de café e possuem ciclo multivoltino os estudos envolvendo o sistema de acasalamento são escassos. Portanto, este trabalho visou estudar o acasalamento da broca-do-café, avaliando se há ocorrência de poliandria e os possíveis efeitos de múltiplas cópulas e cópulas repetidas sobre a bioecologia da fêmea e sua prole. Os resultados revelaram pela primeira vez a ocorrência de poliandria em H. hampei. Foi observado um maior número de recópulas em fêmeas colonizadoras, quando comparado com as fêmeas em oviposição, sugerindo que a condição fisiológica da fêmea foi um fator decisivo no momento da recópula. Além disso, a duração da recópula foi menor nas fêmeas em oviposição do que em fêmeas colonizadoras. A fecundidade foi afetada negativamente pela poliandria, sugerindo a presença de um custo associado a realização de múltiplas cópulas. A longevidade não foi influenciada pelo sistema de acasalamento, demonstrando que a poliandria não influenciou o tempo de vida das fêmeas. A recuperação larva:adulto em H. hampei não foi influenciada pelo sistema de acasalamento. Por outro lado, a taxa de eclosão de larvas foi superior na condição de poliandria, comparativamente à monogamia. / Researches about insects mating systems are important to understand the aspects of reproductive behavior evolution. Mating systems are usually grouped according to the number of mates during mating. Insect females mating system are classified as monogamy when there is only one copulation per male while polyandry refers to multiple mating with different males or with the same male (repeated mating). There is a lack of researches dealing with mating systems in species like the coffee berry borer, Hypothenemus hampei, which spend most of its life cycle (egg to adult) inside of the coffee berry and has a multivoltine cycle. This research aimed to study the mating system of H. hampei females, verifying the existence of polyandry and evaluating the effects of the multiple and repeated mating on the bioecology of the female and its offspring. The current study showed for the first time the occurrence of polyandry on females of H. hampei. The number of remating in colonizing females was higher than in the females under oviposition, thus the female physiological condition is crucial on remating behavior. The copula duration was shorter in females under oviposition than in the colonizing females. Fecundity was negatively affected by polyandry suggesting the existence of costs associated with multiple mating by females. Longevity were not influenced by the mating systems, showing that polyandry does not affect female lifetime. Although egg hatching was superior in polyandry compared to monogamy, the larva:adult recovery rate in H. hampei was not affected by the mating system.