Male pregnancy is a complex and energetically costly form of male parental care found exclusively in the fish family Syngathidae, which includes pipefishes, seahorses, and seadragons. The novelty of the male brood pouch raises questions about how this trait evolved and what role it plays in sexual selection. One possibility is that brood pouch evolution was partially shaped by postcopulatory sexual selection. We used the sexually dimorphic Gulf pipefish, Syngnathus scovelli, to test for postcopulatory sexual selection within broods and tradeoffs between successive male pregnancies as a function of female attractiveness. Offspring survivorship within a pregnancy was affected by the size of a male's mate, the number of eggs transferred, and the male's mating history. These results indicate the males invest more resources into broods from large, attractive mates to the detriment of future broods. Next, we investigated the effects of food limitation on male parental care strategies. Our data suggests that male Gulf pipefish sacrifice investment in future reproduction, via somatic growth, in favor of current reproduction. A positive relationship between number of failed eggs and male growth rate in our low-food treatments suggests that males may derive an energetic benefit from unsuccessful eggs in the brood pouch. Finally, we used a paired design, to investigate the effect of perceived female attractiveness on offspring survivorship. We found that, in general, males prefer the largest female available. Within a replicate, we found that the male that preferred their mate more, regardless of stimulus female size, also had higher offspring survivorship in the resulting brood. This result is exciting because it shows not only that cryptic male choice affects offspring survivorship in Gulf pipefish but also that mate preference can have a prolonged effect on an individual’s reproductive success. Ultimately, our data suggests that the evolution of the brood pouch has produced a trait that not only nurtures the offspring but also exert cryptic male choice.

This thesis examines three factors that may influence the change in protein content and size of the brood food glands in honey bees. Effects on the mandibular gland, involved in the production of brood food and in royal jelly, have not been examined in relation to primer pheromones while effects on the hypopharyngeal glands, also involved in the production of brood food, have not been examined in relation to queen mandibular pheromone. This thesis provides preliminary insight into how these pheromones affect the extractable protein content of brood food glands. The first study in this thesis assessed the effects of brood pheromone (BP), queen mandibular pheromone (QMP), and pollen presence on the protein content of hypopharyngeal and mandibular glands of the honey bee. In this study, newly emerged bees were caged for 12 days in one of eight treatments: Queenless state: 1) control (no pollen + no pheromone), 2) pollen, 3) BP, 4) BP + pollen; Queenright state: 1) QMP, 2) QMP + pollen, 3) BP + QMP, 4) BP + QMP + pollen. This study indicated that regardless of pheromone treatment, the most influential factor on gland protein content and size was pollen. The second experiment examined effects of varying pollen dilution on hypopharyngeal and mandibular gland protein content, bee mass, and lipid content of the honey bee. In this experiment, newly emerged bees were caged for 7 days and fed one of five treatments: pollen, 1:1 pollen: cellulose (vol:vol), 1:2 pollen: cellulose (vol:vol); 1:3 pollen: cellulose (vol:vol), and cellulose. This study indicated that bees on the pollen diet were significantly greater than all other diluted diets in measurements of hypopharyngeal gland protein content, lipid content, and mass with significantly less consumption. However, mandibular gland protein content of bees on the pollen diet was significantly greater only from pure cellulose.

The proximate causes triggering nest abandonment are unclear for most species, including the Yellow Warbler (Dendroica petechia), which abandons nests parasitized by cowbirds (via burial or desertion). Cowbird parasitism and rejection of parasitism are costly to some hosts; therefore cues affecting their responses have important evolutionary implications. Manipulative experiments showed that experimentally adding a cowbird egg elicited similar rejection frequencies (2008: 31.8%; 2009: 26.1%) as naturally laid eggs (2008: 27.1%; 2009: 20.0%). In 2008, interaction with an egg-removing model increased the probability of abandonment and the most aggressive individuals were more likely to bury the model cowbird egg. In 2009, eggs added to nests before sunrise were rejected at a frequency (29.7%) similar to eggs added to nests after sunrise (22.9%). Warblers returning to nests after egg addition peered significantly longer at their clutch than at control nests, shuffled their bodies more frequently when on the eggs and spent more time probing eggs with their bill once settled on their parasitized clutch. Furthermore, although non-mimetic blue eggs were not abandoned significantly more frequently than cowbird eggs (blue 31.1% versus cowbird 21.4%), only blue eggs were ejected from some nests. Thus, warblers use both tactile and visual cues to detect the presence of a parasitic egg in their nest. Eggs added to nests were not rejected at a lower frequency than naturally parasitized nests, as was recorded in a previous study. It is difficult to know whether this increase in abandonment of experimental eggs is due to phenotypic plasticity, genetic changes, or other factors. Egg recognition abilities may have changed because I have shown that the warblers’ behaviour changes before versus after egg addition, whereas no changes were recorded in an earlier study. Finally, not all individuals that buried eggs for the first time in 2009 (21.4%) buried again after being re-parasitized (5.3%), when less time remained in the breeding season relative to the first parasitism event. This suggests that egg rejection and host responsiveness in warblers, and likely other avian hosts that use abandonment as a form of rejection, is affected by environmental cues which may act as genetic expressers.

Obligate brood parasites rely solely on other species, the hosts, to incubate their eggs and raise their offspring, which often reduces the host’s reproductive output. This reproductive cost has led to the evolution of anti-parasite adaptations among hosts, which in turn, has led to better trickery by parasites, a process termed an evolutionary arms race. The objective of this thesis was to investigate host-parasite coevolutionary arms races to address questions of host-use diversity. Host diversity varies dramatically among brood-parasitic species, but reasons for variations in host-use among brood parasites are not well understood. In Chapter 2, I address questions on host diversity specifically, whereas I address questions about coevolutionary interaction between hosts and parasites in Chapters 3, 4 and 5 using two host-parasite systems, one in New Zealand and one in North America. Chapter 2 investigates if host diversity is constrained by aggressive nest defence behaviour. I compared the nest defence behaviour of the exclusive host of the shining cuckoo Chrysococcyx lucidus lucidus on the main islands of New Zealand, the grey warbler Gerygone igata, to two other potentially suitable hosts that are not currently parasitised, the fantail Rhipidura fuliginosa and the silvereye Zosterops lateralis. The results suggest that grey warblers are as aggressive as fantails and silvereyes towards shining cuckoos at the nest and thus, host specialisation in shining cuckoos in New Zealand, at least, does not appear to be the result of nest-defence constraints imposed by potential but unused host species. Chapter 3 investigates if red-winged blackbirds Agelaius phoeniceus, a species that typically accepts the eggs of parasites, recognises, as indicated by changes in incubation behaviour, when they have been parasitised by brown-headed cowbirds Molothrus ater. Recognition without rejection suggests that rejection may be context-dependent but the results suggest that red-winged blackbirds do not recognise when their nests have been parasitised by brown-headed cowbirds, at least at the egg stage. This study was the first to investigate if hosts that almost invariably accept the eggs of parasites recognise when they have been parasitised. Chapter 4 investigated the possibility of coevolutionary arms races occurring through olfactory channels in contrast to earlier work that focussed only on visual and auditory cues. Recent research has revealed that olfactory abilities in birds are more common than previously thought. Uropygial gland secretions are posited to be a key source of avian body odour and its composition has been found to vary among species and individuals as well as between the sexes. I compared gas-chromatography (GC-FID) traces of shining cuckoo preen wax to the GC-FID traces of the grey warbler, the only host of the shining cuckoo in mainland New Zealand, as well as the preen wax of seven other species for evidence of mimicry. Preliminary results suggest there is evidence for mimicry and the potential for odour-based nestling discrimination in grey warblers. Further tests recording the response of grey warblers to odour-manipulated nestlings are necessary. Finally, in Chapter 5, I investigated the response of the song thrush Turdus philomelos, a species that rejects the eggs of the common cuckoo Cuculus canorus and conspecifics at intermediate and low frequencies, respectively, to nest-odour manipulations using the preen wax of conspecifics and heterospecifics. The results suggest song thrush do not use odour to assess the risk of parasitism at least as indicated in terms of changes in incubation behaviour. Investigations of the role of olfaction in avian brood parasite systems can provide a better understanding of brood-parasite coevolution. Only by considering all channels of communication can we be sure to completely understand the coevolutionary dynamics between brood parasites and their hosts.

The proximate causes triggering nest abandonment are unclear for most species, including the Yellow Warbler (Dendroica petechia), which abandons nests parasitized by cowbirds (via burial or desertion). Cowbird parasitism and rejection of parasitism are costly to some hosts; therefore cues affecting their responses have important evolutionary implications. Manipulative experiments showed that experimentally adding a cowbird egg elicited similar rejection frequencies (2008: 31.8%; 2009: 26.1%) as naturally laid eggs (2008: 27.1%; 2009: 20.0%). In 2008, interaction with an egg-removing model increased the probability of abandonment and the most aggressive individuals were more likely to bury the model cowbird egg. In 2009, eggs added to nests before sunrise were rejected at a frequency (29.7%) similar to eggs added to nests after sunrise (22.9%). Warblers returning to nests after egg addition peered significantly longer at their clutch than at control nests, shuffled their bodies more frequently when on the eggs and spent more time probing eggs with their bill once settled on their parasitized clutch. Furthermore, although non-mimetic blue eggs were not abandoned significantly more frequently than cowbird eggs (blue 31.1% versus cowbird 21.4%), only blue eggs were ejected from some nests. Thus, warblers use both tactile and visual cues to detect the presence of a parasitic egg in their nest. Eggs added to nests were not rejected at a lower frequency than naturally parasitized nests, as was recorded in a previous study. It is difficult to know whether this increase in abandonment of experimental eggs is due to phenotypic plasticity, genetic changes, or other factors. Egg recognition abilities may have changed because I have shown that the warblers’ behaviour changes before versus after egg addition, whereas no changes were recorded in an earlier study. Finally, not all individuals that buried eggs for the first time in 2009 (21.4%) buried again after being re-parasitized (5.3%), when less time remained in the breeding season relative to the first parasitism event. This suggests that egg rejection and host responsiveness in warblers, and likely other avian hosts that use abandonment as a form of rejection, is affected by environmental cues which may act as genetic expressers.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2006. / Härtill 4 uppsatser.

Thesis (Ph. D.)--University of Missouri-Columbia, 1996. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1996. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

A presença do marsúpio fechado possibilitou aos isópodos terrestres a total independência do meio aquático para a reprodução, permitindo aos mesmos a colonização de habitats terrestres variados. Em seu interior, a prole é nutrida e oxigenada através de estruturas temporárias, chamadas cotilédones, as quais surgem durante o período ovígero das fêmeas e são exclusivas do grupo Crinocheta. O presente estudo teve como objetivo descrever padrões dos cotilédones, analisados em 37 espécies de isópodos terrestres distribuídas entre as famílias: Agnaridae, Armadillidae, Armadillidiidae, Balloniscidae, Bathytropidae, Detonidae, Dubioniscidae, Philosciidae, Platyarthridae, Porcellionidae, Pudeoniscidae, Scleropactidae e Trachelipodidae, verificando se ocorre variação de comprimento ao longo das fases de desenvolvimento embrionário, sendo que para isto foram selecionadas seis espécies: Armadillidium nasatum, A. vulgare, Atlantoscia floridana, Balloniscus sellowii, Benthana cairensis e Porcellio scaber. Armadillidium vulgare e B. sellowii também foram estimados quanto à proporção comprimento dos cotilédones/ tamanho da fêmea. Entre as 13 famílias estudadas foram identificados seis formatos (tipos) de cotilédones e sete arranjos diferentes de número e distribuição. O comprimento foi estabelecido como: curto, médio e longo. Armadillidium vulgare, A. floridana e B. cairensis não apresentaram diferença no comprimento dos cotilédones durante os estágios embrionários sendo que este foi evidenciado para as demais espécies, uma vez que B. sellowii e P. scaber apresentaram aumento da fase de ovo para embrião, diminuindo na fase de manca. Já em A. nasatum ocorre um aumento gradual até a fase de manca, onde então regridem drasticamente. O comprimento dos cotilédones de A. vulgare e B. sellowii é proporcional ao tamanho da fêmea. Durante os estudos realizados outra novidade foi registrada: a presença de uma “extensão marsupial”. Para maiores informações sobre esta estrutura, foi necessário identificar quais espécies a apresentavam, o número de indivíduos abrigados em seu interior e diferenças na estrutura entre as espécies que portavam tal extensão e as que possuem o marsúpio fechado restrito aos cinco pares de oostegitos. Seis espécies apresentaram extensão marsupial, a qual possibilita o abrigo de aproximadamente ¼ do total da prole. XI Este marsúpio não apresenta formato distendido como o encontrado nas demais espécies o que vem a influenciar diretamente a alimentação da fêmea, pois com o desenvolvimento da prole ocorrendo em direção aos órgãos desta, conforme avançam as fases, aumenta a pressão interna, comprimindo seu interior. As diferenças morfológicas registradas aqui representam estratégias reprodutivas adotadas pelas espécies, ao longo da evolução, podendo estar relacionadas (ou não) à filogenia dos grupos. / The presence of the closed brood pouch made it possible for terrestrial isopods to have full independence of the aquatic environment for reproduction, allowing them to colonize varied terrestrial habitats. Inside, the offspring is nourished and oxygenated by temporary structures, called cotyledons, which emerge during the ovigerous period of females and are unique to the group Crinocheta. This study aims to describe patterns of cotyledons, analyzed in 37 species of terrestrial isopods distributed among the families: Agnaridae, Armadillidae, Armadillidiidae, Balloniscidae, Bathytropidae, Detonidae, Dubioniscidae, "Philoscidae" Platyarthridae, Porcellionidae, Pudeoniscidae, Scleropactidae and Trachelipodidae , checking if there is variation in length along the stages of embryonic development, and for this, six species were selected as models: Armadillidium nasatum, A. vulgare, Atlantoscia floridana Balloniscus sellowii, Porcellio scaber and Benthana cairensis. Armadillidium vulgare and B. sellowii were also estimated concerning the proportion of cotyledon length / female size. Among the 13 studied families six formats (types) of cotyledons were identified as well as seven different arrangements of numbers and distribution. The length was established as: short, medium and long. Armadillidium vulgare, A. floridana and B. cairensis showed no difference in the length of the cotyledons during the embryonic stages while this was evidenced for the other species, since B. sellowii and P. scaber showed increased egg stage to the embryo, decreasing during the manca. Nevertheless in A. nasatum a gradual increase until the phase of manca occurs, which then regresses dramatically. The length of the cotyledons of A. vulgare and B. sellowii is proportional to female size. XIII During the carried out studies another new feature was recorded: the presence of an " marsupial extension." For obtaining further information about this structure it was necessary to identify the species that presented it, the number of individuals housed within, and differences in structure between species that harbored such extension and the others which had the closed pouch restricted to five pairs of oostegits. Six species showed marsupial extension, which provides shelter for approximately a quarter of the total offspring. This brood pouch does not have a distended format as the one found in other species, which directly influences the feeding of the female, because due to the fact that the offspring development occurs towards its organs as the stages advance, internal pressure increases, compressing its interior. The morphological differences reported here represent reproductive strategies adopted by the species, through evolution and could be related (or not) to the phylogeny of the groups.

A presença do marsúpio fechado possibilitou aos isópodos terrestres a total independência do meio aquático para a reprodução, permitindo aos mesmos a colonização de habitats terrestres variados. Em seu interior, a prole é nutrida e oxigenada através de estruturas temporárias, chamadas cotilédones, as quais surgem durante o período ovígero das fêmeas e são exclusivas do grupo Crinocheta. O presente estudo teve como objetivo descrever padrões dos cotilédones, analisados em 37 espécies de isópodos terrestres distribuídas entre as famílias: Agnaridae, Armadillidae, Armadillidiidae, Balloniscidae, Bathytropidae, Detonidae, Dubioniscidae, Philosciidae, Platyarthridae, Porcellionidae, Pudeoniscidae, Scleropactidae e Trachelipodidae, verificando se ocorre variação de comprimento ao longo das fases de desenvolvimento embrionário, sendo que para isto foram selecionadas seis espécies: Armadillidium nasatum, A. vulgare, Atlantoscia floridana, Balloniscus sellowii, Benthana cairensis e Porcellio scaber. Armadillidium vulgare e B. sellowii também foram estimados quanto à proporção comprimento dos cotilédones/ tamanho da fêmea. Entre as 13 famílias estudadas foram identificados seis formatos (tipos) de cotilédones e sete arranjos diferentes de número e distribuição. O comprimento foi estabelecido como: curto, médio e longo. Armadillidium vulgare, A. floridana e B. cairensis não apresentaram diferença no comprimento dos cotilédones durante os estágios embrionários sendo que este foi evidenciado para as demais espécies, uma vez que B. sellowii e P. scaber apresentaram aumento da fase de ovo para embrião, diminuindo na fase de manca. Já em A. nasatum ocorre um aumento gradual até a fase de manca, onde então regridem drasticamente. O comprimento dos cotilédones de A. vulgare e B. sellowii é proporcional ao tamanho da fêmea. Durante os estudos realizados outra novidade foi registrada: a presença de uma “extensão marsupial”. Para maiores informações sobre esta estrutura, foi necessário identificar quais espécies a apresentavam, o número de indivíduos abrigados em seu interior e diferenças na estrutura entre as espécies que portavam tal extensão e as que possuem o marsúpio fechado restrito aos cinco pares de oostegitos. Seis espécies apresentaram extensão marsupial, a qual possibilita o abrigo de aproximadamente ¼ do total da prole. XI Este marsúpio não apresenta formato distendido como o encontrado nas demais espécies o que vem a influenciar diretamente a alimentação da fêmea, pois com o desenvolvimento da prole ocorrendo em direção aos órgãos desta, conforme avançam as fases, aumenta a pressão interna, comprimindo seu interior. As diferenças morfológicas registradas aqui representam estratégias reprodutivas adotadas pelas espécies, ao longo da evolução, podendo estar relacionadas (ou não) à filogenia dos grupos. / The presence of the closed brood pouch made it possible for terrestrial isopods to have full independence of the aquatic environment for reproduction, allowing them to colonize varied terrestrial habitats. Inside, the offspring is nourished and oxygenated by temporary structures, called cotyledons, which emerge during the ovigerous period of females and are unique to the group Crinocheta. This study aims to describe patterns of cotyledons, analyzed in 37 species of terrestrial isopods distributed among the families: Agnaridae, Armadillidae, Armadillidiidae, Balloniscidae, Bathytropidae, Detonidae, Dubioniscidae, "Philoscidae" Platyarthridae, Porcellionidae, Pudeoniscidae, Scleropactidae and Trachelipodidae , checking if there is variation in length along the stages of embryonic development, and for this, six species were selected as models: Armadillidium nasatum, A. vulgare, Atlantoscia floridana Balloniscus sellowii, Porcellio scaber and Benthana cairensis. Armadillidium vulgare and B. sellowii were also estimated concerning the proportion of cotyledon length / female size. Among the 13 studied families six formats (types) of cotyledons were identified as well as seven different arrangements of numbers and distribution. The length was established as: short, medium and long. Armadillidium vulgare, A. floridana and B. cairensis showed no difference in the length of the cotyledons during the embryonic stages while this was evidenced for the other species, since B. sellowii and P. scaber showed increased egg stage to the embryo, decreasing during the manca. Nevertheless in A. nasatum a gradual increase until the phase of manca occurs, which then regresses dramatically. The length of the cotyledons of A. vulgare and B. sellowii is proportional to female size. XIII During the carried out studies another new feature was recorded: the presence of an " marsupial extension." For obtaining further information about this structure it was necessary to identify the species that presented it, the number of individuals housed within, and differences in structure between species that harbored such extension and the others which had the closed pouch restricted to five pairs of oostegits. Six species showed marsupial extension, which provides shelter for approximately a quarter of the total offspring. This brood pouch does not have a distended format as the one found in other species, which directly influences the feeding of the female, because due to the fact that the offspring development occurs towards its organs as the stages advance, internal pressure increases, compressing its interior. The morphological differences reported here represent reproductive strategies adopted by the species, through evolution and could be related (or not) to the phylogeny of the groups.