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The biology of reproduction in two British pulrnonate slugs. The biology of reproduction has been studied in two British slugs, Deroceras reticulatum (Muller) and Anon hortensis (Frussac). The morphogenesis, histology and ultrastructure of the carrefour and anterior genital ducts have been described and discussed in relation to their function. The carrefour morphology of other slugs has been examined. The limacid carrefour is comparable to the basic stylommatophoran arrangement but in the Anionidae it is much simplified. It is concluded that the Arionidae could be an early offshoot from the main line of stylontmatophoran evolution. Evidence for the environmental control of reproduction in pulmonates has been reviewed. Experimental studies indicate that reproductive development and the onset of maturity are controlled by photoperiod. Short days retard and long days accelerate growth and reproductive development. Subsequent reproductive activity is unaffected by photoperiod. Temperature, humidity and food availability have an immediate effect on egg-laying. In general, conditions favourable to the survival of the embryos enhance egg-production. None of these factors induce courtship and copulation but, generally, adverse conditions are inhibitory. Under apparently constant conditions the animals displayed periods of reproductive activity suggesting an endogenous rhythm. This may contribute to the synchronization of breeding cycles in the field. The behavioural and functional changes during courtship, copulation and egg-laying have been described. During courtship the sperm's movement along the reproductive tract follows a consistent chronological pattern. At copulation the sperm packages are inserted directly into the entrance of the bursa copulatrix, but only sperm released before the package has completely entered the bursa travels up the reproductive tract. This sperm is not stored in the carrefour but passes through into the seminal vesicle where it mixes with the animal's own sperm. At egg-laying the oocytes accumulate in the carrefour although fertilization does not necessarily occur there. The incidence of self-fertilization in the pulmonates is discussed.

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The evolution of wind pollination (anemophily) has occurred at least 65 times in the flowering plants and over 10% of angiosperm species are wind pollinated. However the pollination and mating of anemophily species is poorly understood, particularly in comparison with animal-pollinated species. My thesis employs a range of approaches and tools to examine the evolution and ecology of wind pollination. These include comparative analyses, theoretical modeling, field and glasshouse experiments, the use of genetic markers and quantitative genetics. Experimental studies on diverse taxa were used to address questions concerned with the efficacy of outcrossing mechanisms, the ecological and demographic context of pollination and mating, and the plasticity of sex allocation. Comparative analyses indicated that wind pollination is correlated with unisexual flowers, reduced ovule number, small unshowy flowers, an absence of nectar, and open habitats. These analyses also demonstrated that anemophily originates more often in lineages with unisexual flowers. This suggests that wind pollination evolves in diclinous taxa as a mechanism of reproductive assurance because autonomous selfing is mechanically precluded. Empirical data on stigmatic pollen loads in 19 anemophilous species challenge the widespread assumption that anemophilous plants commonly have uniovulate flowers because they capture few pollen grains. Further, a model based on floral costs and the aerodynamics of pollen capture demonstrated that when flowers are inexpensive it is optimal to produce many flowers each with few ovules, because this allows more efficient sampling of the airstream. Manipulative field experiments on seven Carex species indicated that neither monoecy nor protogyny, two putative outcrossing mechanisms, are effective at limiting selfing. Based on these results I suggest that geitonogamy can provide reproductive assurance in anemophilous species with unisexual flowers. Field experiments and the application of sex-specific markers in Rumex nivalis revealed that the local neighbourhood of maternal plants affects pollination intensity and progeny sex ratios. Finally, I demonstrated that plant density in Ambrosia artemisiifolia affects stigmatic pollen loads but not outcrossing rates. Through a quantitative genetics experiment in A. artemisiifolia, I detected significant genetic variation for plasticity in sex allocation, potentially enabling adaptive adjustment of sex allocation to local environmental conditions.

Hagfish are one of the more lucrative commercial opportunities in the world with fisheries harvesting them specifically for food and for their skin for leather-based products. In 2013 a three year experimental fishery opened off the west coast of Vancouver Island, British Columbia in order to determine the sustainability of a Pacific hagfish (Eptatretus stoutii) and Black hagfish (Eptatretus deani) fishery. In this study, I examined the reproductive biology of both species including: length-weight relationships, sex ratios, fecundity, and size-at-gonadal development. This study corroborates previous suggestions that Pacific hagfish are juvenile protogynous hermaphrodites while black hagfish are likely to be dioecious with an unknown juvenile stage. Sexual dimorphism appears in both species of hagfish, which is likely the result of inter- and intraspecific morphological differences. For both species fecundity decreases throughout developmental stages, and the average fecundity is very low (27-32 eggs per female). Additionally, in both species females commence gonadal development prior to males. Furthermore, both species exhibited extreme female: male sex ratios across length-classes, however, in opposite directions. The reproductive biology of Pacific and Black hagfish models that of a k-selected species, which is a species that tends to live long and has a slow growth rate, low fecundity, and late maturity. As a result there are a variety of concerns that should be addressed when developing a sustainable hagfish fishery to prevent collapses observed in previous hagfisheries. / Graduate / 2017-08-23