Arthropods are the most species-rich group of animals, and as such they exhibit an amazing diversity of morphological, behavioral, and ecological adaptations. Because of this diversity, the evolutionary history of this group has been, and still is notoriously difficult to determine because considerations of different traits invariably support alternative evolutionary relationships. Their nervous systems provide an invaluable set of characters for systematic inferences about the origins and evolutionary trajectories of Arthropoda. This is because nervous systems are ubiquitous and contain a wealth of structures from which to infer shared ancestry. Considerations of ancestral arthropod relationships have further provided insights into how arthropod nervous systems have maintained some traits through evolutionary time and how others have been modified or acquired as novelties. This dissertation explores the evolution of arthropod brains within an interdisciplinary framework, utilizing comparative neuroanatomical, neural cladistic, and molecular phylogenetic analyses to support novel hypotheses of nervous system evolution in arthropods. The field of neurophylogenetics relies on the characterization of shared derived neural traits to infer ancestry amongst taxa. The first portion of this work describes highly conserved neural elements from the lamina, or first optic neuropil, of several crustaceans. This study is followed by a neural cladistic study that infers evolutionary relationships amongst major arthropod groups based solely on neural traits. The results of this study are then compared to those from a large-scale molecular phylogenomic analysis of hundreds of conserved orthologous genes. Results from neural cladistic and molecular phylogenetics suggest several species whose neuroanatomical characterization would provide support for novel evolutionary hypotheses. The last portion of this dissertation details a comparative neuroanatomical study on one such diagnostic taxa, the copepod Tigriopus californicus. Two principles of arthropod nervous system organization and evolution are repeatedly supported with this approach: 1) many complex neural structures shared amongst arthropod groups have been inherited from ancient common ancestors, suggesting that the neural arrangements seen today have been carried over from antiquity; and 2) these same complex attributes are absent in numerous late-diverging lineages, supporting the hypothesis that secondary simplification of nervous systems is a common property of arthropods.

Benthic mobile invertebrates are important components of coral-reef diversity and community structure, though, in most cases, their ecological contributions are poorly known. Baseline information on their diversity, prevalence, assemblages, and ecological roles is needed to aid in the conservation of coral-reef habitats. The objectives of this study are to 1) describe diversity and assemblages of epibenthic, mobile invertebrates in shallow water coral-reef communities in Florida, 2) evaluate their ecological roles by reviewing published literature on diet, and 3) measure the degree of linear dependence between mobile invertebrates and scleractinian corals. Underwater surveys were conducted in the summer of 2013 at 40 sites distributed along the Florida Reef Tract from Broward County to the Dry Tortugas. The presence/absence of all mobile, epibenthic invertebrate fauna observed were recorded and identified to the lowest level possible. The survey data include 618 records of 116 unique taxa, 83 species, 61 genera, 46 families, 19 orders, seven classes, and four phyla of mobile invertebrates, comprising herbivores, detritivores, carnivores, omnivores, and suspension feeders. These taxa represent 22% of the comparable taxa in a historical dataset that spans 60 years, plus an additional 18 taxa. The survey data also show that the percent composition of major phyla is similar to the historical dataset, despite taxonomic bias evident in the historical dataset. During the survey, novel unique taxa were encountered frequently, but were seldom recurrent, which highlights their cryptic nature. While regional patterns were not identified in the study, assemblages of dominant taxa were characteristic of reef type: echinoderms were the most diverse on patch reefs and southeast Florida reef complexes, mollusks were most diverse on shallow bank reefs, and arthropods were diverse on deep bank reefs, Southeast Florida reef complexes, and shallow bank reefs. Herbivorous mobile invertebrate diversity was negatively correlated with scleractinian coral diversity, underlining competition between corals and macroalgae, and association of herbivores with macroalgae. All of these results suggest that reef types are distinct, but interrelated communities of fauna having specific habitat requirements and important roles. This study also reinforces the challenges in assessing the diverse and often cryptic mobile invertebrate fauna and emphasizes the need for further research and monitoring to detect changes in their communities for the conservation of Florida reef systems.

Includes copies of author's previously published works / Guano deposits in caves form a rich food resource supporting diverse arthropod communities. Guano piles consist of distinct micro - habitats, fresh, moist, highly basic guano and older, dry, slightly acidic guano. Micro - habitat variation is strongly controlled by seasonal guano deposition that, in turn, effects the structure of arthropod communities. The maternity chamber of Bat Cave, Naracoorte, South Australia, contains extensive guano deposits supporting 38 species from three classes and 12 orders. This community was studied to determine spatial and temporal variation of arthropod communities, and biogeographic relationships between different regions in Australia. Species richness forms a positive linear relationship with pH, in situ moisture content and guano deposition. Many species show strong associations with fresh guano and hence are strongly seasonal, although some species are present throughout the year. Arthropod community structure in winter was found to be more closely related to prior summer arthropod structure than to subsequent seasons. Starlight Cave near Warrnambool, western Victoria, the only other maternity site for Miniopterus schreibersii bassanii, contained 43 species from 39 families and 14 orders. Seven species are common to both caves. The community structure of Starlight Cave was found to be more homogeneous than Bat Cave with samples clustering by season rather than sample year as was the case at Bat Cave. Different cave morphology was found to significantly alter the micro - habitat conditions and, hence, community structure in Starlight Cave compared with Bat Cave. Migration of guano associated arthropods at local, regional and continental scales was assessed using mtDNA and allozyme electrophoresis the pseudoscorpion genus Protochelifer as a model organism. Phylogenetic tree reconstruction revealed a wide geographic distribution of cavernicolous species across southern Australia. Cave colonisation is believed to have occurred only once, followed by dispersal to the Nullarbor Plain and other caves in south - eastern Australia. Dispersal was possibly phoretic on cave bats or occurred prior to aridification of surface environments that currently restricts migration. The distribution of guano - associated arthropods from arid, semi - arid and monsoonal karst areas in Australia are compared with temperate south - eastern Australia. Different climatic areas show large biogeographical differences in community structure, although similar families ( Urodinychidae, Reduviidae, Anobiidae, Carabidae and Tineidae ) are present in many Australian guano communities. Several potential mechanisms of dispersal are discussed including phoresy, colonisation from soil, terrestrial migration and interstitial cavities. Endemism to specific caves cannot be definitely assigned to any species, although 13 species show restricted distribution. / Thesis (Ph.D.)--School of Earth and Environmental Sciences, 2006.

This dissertation describes arthropod responses to and effects on decay processes in ponderosa pine, a dominant forest canopy tree in northern California. We used both descriptive and experimental field techniques to establish how arthropod assemblages depend on and are important to the disintegration of woody structures in forests of this type. The first study used pitfall traps placed within and on the outsides of fallen, large old ponderosa pine trees to establish the effects of microenvironments created during tree death. We studied the internal and external structures of fallen trees as well as the forest floor in canopy gaps and in the surrounding undisturbed forest. Five trees were surveyed, representing a decay sequence from newly dead and with distinct canopy gap, to well-decayed with recovering canopy. Arthropod assemblages were distinct among the different microenvironments, but were less so with increasing tree/gap age. Differences between tree and soil faunae decreased with increasing decay, as did the differences between gap and non-gap catches from the forest floor. The second study used experimental exclusion techniques to examine how longitudinal (bark beetle) and transverse (woodboring) insect colonists could influence rates of mass loss and carbon respiration from young, dead ponderosa pine. We found that both groups enhanced the prevalence of staining fungi in the sapwood, which in turn was negatively related to the degree of structural failure in the sapwood, associated with decay fungi. Carbon respiration was positively related to sapwood structural failure and we believe that the two insect groups act in concert to suppress wood decomposition in this system. This is contrary to prevailing wisdom among forest practitioners who have suspected that decay and insect activity are positively correlated, but in agreement with laboratory studies showing antagonism between stain and decay fungi. Lastly, we observed that neither forest harvesting nor fire had strong effects on the development of exemplar taxa from decay communities in ponderosa pine two years post-treatment. Though time since treatment did affect all functional groups inside of logs, only undisturbed old-growth treatments showed a reduced variability in composition, leading us to suspect effects to emerge at longer time intervals. / Graduation date: 2004

The structuring of canopy arthropod communities was reviewed and investigated in relation to tree species diversity and its component factors, interspersion of different species and density of each tree species. Fifteen treatments of Douglas-fir (Pseudotsuga menziesii) and red alder (Alnus rubra) (various densities and proportions of each) were randomly assigned to 0.073 ha plots, replicated three-fold at each of two locations in Western Oregon: the Cascade Head Experimental Forest and the H.J. Andrews Experimental Forest. The six treatments used in this study were two densities of Douglas-fir and red alder monoculture (1000 trees/ha and 500 trees/ha), and mixtures of Douglas-fir and red alder (500 trees/ha of each) planted simultaneously or red alder planted 6 years after the Douglas-fir. Trees were initially planted in 1985-1986. The arthropod communities were sampled in the summer of 1998 by bagging and pruning branches from the mid-canopy of both tree species. Multivariate analyses distinguished the arthropod communities found on each tree species and geographical location, but not among the different diversity and density treatments. Many arthropod taxa and functional groups residing on a single tree species had significantly different abundances between locations. The most commonly encountered taxon, Adelges cooleyi Gillette (Homoptera: Adelgidae), was most abundant on Douglas-firs in the 500 trees/ha monoculture and the mixture with younger red alder, and least abundant in the mixture with both species planted simultaneously (the 1000 trees/ha Douglas-fir monoculture was intermediate). Adelgids showed no significant response to location, but did respond to combinations of location x treatment. The functional group of sap-feeders was dominated by adelgids, and showed similar treatment differences on Douglas-fir. Defoliators on red alder responded in abundance to location, treatment (most abundant in the 500 trees/ha monoculture and even-aged mixture, least abundant in the 1000 trees/ha monoculture), and location x treatment. This study demonstrated that tree species and geographical location are the primary determinants of forest arthropod community composition at this spatial scale. However, tree species diversity and density can affect the abundance of certain arthropod taxa, apparently through some combination of resource quality and plant apparency. / Graduation date: 2000

The "old-growth controversy" in the Pacific Northwest recognized thinning as the primary silvicultural practice for land managers to produce wildlife habitat while continuing to produce timber. For the foreseeable future, forest stands will be harvested to produce forest gaps and a patchwork of trees of different ages. In order to evaluate the effect of thinning on biodiversity, nine 15-year-old harvests of this type (age=70 years) were paired with adjacent old-growth and even-aged, unthinned "pole" stands. Since soil is the crucible of terrestrial biodiversity, it is critical to contrast the effects upon the forest floor of this future practice with current management. Soil and litter fauna were monitored along 250 meter transects (pitfall and Berlese sampling at ten-meter intervals) to meet the following objectives: 1) to determine biological diversity on public lands, per federal mandate, and use diversity as a management tool; 2) compare levels of biodiversity between three management strategies; 3) determine best methods to assay arthropod diversity; and 4) identify structural and environmental determinants of arthropod diversity and abundance. The study's hypotheses were: 1) old-growth forests will have greater arthropod diversity than thinned stands; 2) thinned stands will have greater arthropod diversity than unthinned stands; and 3) species found within old-growth stands, but not within unthinned pole stands, will also be found in thinned stands. This study contrasted nine Western Hemlock/Douglas-fir sites each with contrasting old-growth, thinned and unthinned pole management stands. Sites were equally blocked in Southern Oregon, the Coast Range, and the Cascade Mountains. No segment of the arthropod fauna. (i.e., pitfall-trapped epigeic macroarthropods, Berlese-extracted litter-dwelling meso- and microarthropods, or soil-dwelling microarthropods) exhibited a management (treatment) effect throughout the entire region. When the regional blocking was removed, within-region analysis generally revealed that old-growth was most distinct. Old-growth stands had the highest abundance of individuals, but were comprised of the fewest species. Thinned stands were characterized by the highest species richness. Within-region analysis revealed an interaction of management effects and specific locale effects; locale effects dominated for soil microarthropods and epigeic macroarthropods, while management options dominated for litter arthropods. Within the Southern Oregon region, I attempted to correlate arthropod community structure (canonical correspondence analysis (CCA) of within-stand samples) with a suite of soil chemical and microbiological descriptors. Full analysis of twelve variables within one exemplary stand revealed several potential trends (negative: dissolved organic carbon, soil moisture, distance from the beginning of the transect; positive: total CO��� field respiration, mineralizable nitrogen, water-induced respiration, substrate-induced respiration). Relatively shallow slopes and very low r-value coefficients of correlation characterized all statistical tests. Few of the trends apparent at one site were paralleled at more than one other site; at all sites potential correlates had very low r-values. No community revealed separate clouds in CCA analysis, indicating distinct "micro-communities" of arthropods inhabiting distinct micro-habitats. Lack of distinctive species assemblages and lack of correlation with microhabitat variables indicated that arthropods respond on different temporal and/or spatial scales then the microbial-oriented variables, and that each taxon is responding in an individual manner. / Graduation date: 1998

Despite the recognized role of soil arthropod fauna on nutrient cycling and decomposition processes, many aspects of the effects of sylvicultural methods in forest ecosystems upon their biology remain poorly understood. The long term effects of prescribed fires on soil arthropods in forest ecosystems in the Pacific Northwest have never been studied. Soil samples were taken from three sites located in the Willamette National Forest in 1992: paired sites that were either clear-cut without burning and clear-cut with burning 40 years ago. One hundred and eight samples were processed; the arthropods were separated, identified and counted. To study the biology and behavior of some arthropods, eight species of oribatid mites were reared in laboratory conditions. Their life cycle, feeding behavior and reproduction were studied. Results indicated that there were no statistical significant treatment differences either in terms of total numbers of organisms or biomass. However, the majority of the commonest taxa did show offsetting treatment responses. A total of 204 taxa were found in the three sites. The most important groups included Collembola, mites, and insects. Other groups also represented, but in smaller numbers, were spiders, symphylans, pseudoscorpions, and centipedes. Of all these groups, oribatid mites was the best represented and appears to be a useful indicator of disturbances. / Graduation date: 1995

The diversity and abundance of the arthropod nest fauna of House Sparrows (Passer domesticus (L.)) and Tree Swallows (Tachycineta bicolor (Vieillot)) in southern Quebec were studied. Over 90,000 arthropods were extracted from the nests, including at least 71 species (50 families) of insects and at least 11 species (8 families) of mites. There were no significant differences in the species richness or diversity of nest arthropods from year to year (1997--1998), or from nest to nest within either host species. There was no significant difference in the overall species richness or diversity between House Sparrows and Tree Swallows. Cluster analyses of species richness and three diversity indices for all nests showed no clustering according to bird species. However, there were some significant differences in the abundance and diversity of particular arthropod taxa between the two bird species, with different ectoparasitic and non-ectoparasitic species dominant in the nests of each host species.

Cousine Island, Seychelles, is of major conservation significance as it is relatively pristine, and apparently the only tropical island over 20 ha with no alien invasive mammals. Such mammals, especially rodents, can impact substantially on arthropod faunas. This study focuses on the arthropods of the island that live in fallen logs and litter. The dominant log species are Pisonia grandis (Summerhayes, 1932), Ficus spp. and Cocos nucifera (Linnaeus, 1952). Stage of decomposition and forest type in which the logs occurred significantly influenced the composition and structure of the assemblages. Young logs were significantly richer in species than older logs, possibly due to the greater resources and more varied microhabitats in the younger logs. Log type was also important for arthropod species richness and abundance. Although P. grandis and Ficus spp. logs did not differ significantly, these two log types did differ greatly from C. nucifera which had a higher arthropod species richness, composition and abundance. However, these differences were only significant for recently fallen logs. As the logs decayed, their arthropod assemblages converged. Nevertheless, each log type had some arthropod species not present in another log type. This is important in terms of conservation, especially in the case of C. nucifera, which, according to one school of thought, should be removed from some Seychelles islands as it is considered an alien invasive. Arthropod assemblages in woody litter differed in composition depending on forest type in which they occurred. These woody litter assemblages were generally dissimilar to those in logs in the same forest type. Leaf litter was extremely poor in arthropod species. Species richness, both in logs and litter, was comparable to figures from temperate lands, possibly because the rich, topical fauna was ameliorated by small island size. As the logs are home to several Seychelles endemic species, their conservation is essential. Furthermore, as they are also the food base of certain threatened Seychelles vertebrates, their conservation is about conservation of a food chain on this unique tropical island. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2001.

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