No description available.

Coevolutionary interactions change across landscapes, leading to the formation of geographic selection mosaics. Analyses of coevolutionary dynamics have so far focused on interactions between two trophic levels. The tritrophic interactions between the pierid butterfly Anthocharis cardamines (the orange-tip), its brassicaceous host-plants Cardamine pratensis (lady's smock) and Alliaria petiolata (garlic mustard), and primary parasitoids Phryxe vulgaris (Tachinidae) and Cotesia saltator (Braconidae), are known to vary across mainland Britain and Continental Europe. In Britain, northern A. cardamines populations tend to utilize C. pratensis and southern ones A. petiolata; the primary parsitoid in this country is P. vulgaris. In Sweden, the butterfly does not show a strong preference for any brassicaceous hostplant, and the primary parasitoid is C. saltator. In this thesis, I investigate likely selection pressures operating on these interactions in a single study site on the Wirral peninsula in northern England. Host use affects the emergence timing and dispersal of A. cardamines males; specimens utilizing C. pratensis emerge earlier than those utilizing A. petiolata, and are also smaller. Since small size is linked with depressed dispersal, utilization of C. pratensis results in an "emerge early and wait" mate seeking strategy; conversely, utilization of A. petiolata is associated with an "emerge late and rove" strategy. These alternative strategies are likely adapted to the varying density of locally emerging females across the landscape, with high density populations tending to be associated with C. pratensis and low density ones with A. petiolata. In dense populations, late emerging males will be at a disadvantage since females mate only once; in the study population, their predicted fitness always declines to < 1 in late season. This is coupled with a 'stay-or-go' response, in which a proportion of late emerging males immediately emigrate to a low density continuum outside the study area, where early emergence is less critical for fitness. Such a response could help maintain sink populations by averting Allee effects (decreased population growth due to low mate encounter rates). Late instar A. cardamines larvae are heavily parasitized by P. vulgaris. This could select for early vacation of the host-plant at small larval size, whereas the size-fecundity relationship in females should select for prolonged growth to larger size. Mathematical models indicate that high rates of parasitization are sufficient to overturn the fecundity benefit of large size, but fall short of maintaining strong stabilizing selection for an optimal winglength. The tendency of some larvae to move off their host-plant before the final instar resting phase is probably a direct evolutionary response to parasitism risk. A. cardamines larvae are pre-dispersal seed-predators; an early flowering ecotype of C. pratensis has likely been selected to avoid egg-laying A. cardamines females. In turn, the butterfly appears to be invading this host-plant's phenological space, with selection favouring small, early emerging females which oviposit on it. This cautions against interpreting the recent advance in A. cardamines' phenology solely in terms of a response to climate change. Spatio-temporal variation in the intensity of these effects likely contributes to the ongoing coevolutionary dynamics within this tritrophic system.

Heliconius butterflies are found across the neo-tropics, with bright aposematic colour patterns. These Müllerian mimics show striking colour pattern convergence across species, while paradoxically showing striking diversity within species. Thus Heliconius wing patterns have become an excellent system for understanding the repeatability of evolution. This work has identified a number of genes that appear to be involved in colour pattern control across species, such as optix and cortex, which respectively control red and yellow pattern elements. However, this work has only looked at the genetic basis of colour pattern in a small number of species, and primarily focusses on just two; H. melpomene and H. erato. I first use a population genomics approach to try to identify whether optix controls the hindwing rays phenotype in two poorly studied species; H. demeter and H. aoede. I identify both divergence associated with colour pattern at this optix, as well as another putative colour pattern control locus in H. aoede, the ommochrome pathway gene cardinal. Further, I use Quantitative trait loci analysis to explore the genetics of colour pattern in H. melpomene, confirming WntA as the gene controlling the ‘broken band’ phenotype and I identify a locus associated with red-orange pigmentation, while also exploring the role of minor effect loci in quantitative colour pattern variation. Finally, I use the natural diversity at two hybrid zones, in conjunction with phylogenetic discordance at mimicry loci, to identify putative regulatory enhancers associated with colour pattern shifts, investigate introgression across species at this fine genetic scale, and the possible role of colour pattern introgression in Heliconius speciation. This work reveals both interesting cases of convergent genetic evolution, independent genetic evolution and introgression, showing that a variety of evolutionary processes have shaped Heliconius mimicry across species.

The Rothamsted Insect Survey (RIS) light-trap network has been running for nearly 30 years and has amassed a vast quantity of spatial and temporal data for over 600 species of moths. The RIS has played an central role in the development of Taylor's Power law which states that for a given species sampled under similar circumstances, sample variance will be a power function of the mean. Using 13 years data from the RIS to produce TPL parameters, Taylor & Woiwod (1982) predicted that the addition of a second decade of data would not change the parameter estimates. This prediction was tested and a small but significant number (8.7%) of species were found to change parameter values. It is unlikely that this disproves Taylor's Power Law and is probably indicative of environmental change. The range of means used to estimate the TPL parameters was discovered to be of crucial importance and should be greater than 0.4. Traditional measures of spatial pattern used in ecology use only the mean and variance of samples, ignoring the spatial relationship of the counts. SADIE (Spatial Analysis by Distance IndicEs) is a novel method of spatial analysis which uses all available spatial information within the data to produce two indices, Ia and Ja. Before applying SADIE to the RIS data, the performance of SADIE given a variable sampling density was examined. Ia was found to systematically underestimate spatial pattern under variable sampling density. Ja was less affected by sample density although it is incapable of detecting pattern when more than one cluster is present. A new SADIE-like methodology was devised called Multiple Foci SADIE (MF-SADIE) which extends the Ja concept to data sets with multiple clustering and produces a new index Fa. MF-SADIE was then applied to 23 species of moth from the RIS to look for temporal pattern in their spatial distribution. A range of spatio-temporal patterns was found, from cyclical to almost uniform with good correlation between species sharing food plant types.

No description available.

No description available.

No description available.

No description available.

No description available.

No description available.