Evolutionary transitions between marine and freshwater habitats are rare events that can have profound impacts on aquatic biodiversity. The main goal of my thesis is determining the processes involved in transitions between marine and freshwater biomes, and the resulting patterns of diversity using phylogenetic approaches. To test hypotheses regarding the geography, timing, frequency, and mechanisms regulating biome transitions I generated multi-locus time-calibrated molecular phylogenies for groups of fishes that include both exclusively marine and freshwater species. My analysis of anchovies demonstrated that Neotropical freshwater anchovies represent a monophyletic radiation with a single origin in South American freshwaters. I used a phylogeny of herring and allies (Clupeiformes) to investigate the evolution of diadromy, a migratory behavior in which individuals move between oceans and freshwater habitats for reproduction and feeding. These analyses do not support the hypothesis that differences in productivity between marine and freshwater explain the origins of diadromous lineages. Diadromy has been considered an evolutionary pathway for permanent biome transitions, however I found that diadromy almost never produces a fully marine or freshwater clade. Marine lineages often invade continental freshwaters during episodes of marine incursion. In South America, the rich diversity of marine derived fish lineages invaded during Eocene marine incursions from either the Pacific or the Caribbean, and Oligocene marine incursions from the Caribbean. I falsified the highly cited Miocene marine incursion hypothesis, but found that the Pebas Mega-Wetland catalyzed diversification in some marine derived lineages. Using diversification analyses, I investigated the evolutionary processes that have generated disparate patterns of diversity between continents and oceans. I found that freshwater silversides have higher speciation and extinction rates than marine silversides. Lineages accumulation plots suggest ecological limits are not regulating clade growth in either marine or freshwater biomes. Overall, biome conservatism is a widespread pattern among fishes, and this pattern is largely driven by competition in clades that are physiologically capable of biome transitions. Biome transitions are facilitated by rare paleogeographic events, such as marine incursions. Finally, a difference in net diversification rate is the macroevolutionary mechanism that best explains the difference in diversity between continents and oceans.

Thesis (B.A.Hons.) - Dept. of Geography, University of Adelaide, 1977. / Includes bibliographical references (p. 28-29).

Project (M.S.)--Brigham Young University. Dept. of Biology, 2007. / Includes bibliographical references (p. 29-36).

Thesis (Ph. D.)--University of Texas at Austin, 2005. / Supervisors: William Doolittle and Gregory Knapp. Vita. Includes bibliographical references.

I studied molecular phylogeny and historical biogeography of the hawkmoth genus Agrius, a group with several migratory as well as several strictly endemic species. I used sequences of one mitochondrial and one nuclear genes and in a detail also population genetic parameters of the most widespread species, Agrius convolvuli.

The mesic forests distributed within the Rocky Mountains of northern Idaho are unique because many species contained within the forest are separated from their main distribution along the Pacific Northwest coast. It remains unclear whether most species within the inland disjunction survived the glacial periods of the Pleistocene, or whether they were more recently dispersed from coastal populations. To see if the dominant tree taxa of the mesic forests today could have persisted in a refugium south of the large ice sheets, four sediment cores were used to reconstruct the vegetation and climate history of the region. A nearly continuous record of pollen and sediment composition (biogenic silica and inorganic and organic matter) over the last ca. 120,000 years provides evidence of a dynamic ecosystem. Over a long timescale, the slow shifts in vegetation are attributed to the changes in climate. During the last interglacial period, the region was warmer and drier with a Pinus dominated mixed conifer forest. Approximately 71,000 years ago, a Pseudotsuga/Larix forest became established in the area as a response to the increased available moisture. As climate cooled and glaciers expanded the Pinus and Picea forest was the dominant vegetation type until ca. 40,000 years ago. The environment during the Last Glacial Maximum (LGM) was so harsh that no vegetation record was recorded. After the LGM, climate warmed, enabling a Pinus and Picea forest to establish and persist until the Holocene. The mesic taxa that dominate the modern forests did not arrive in northern Idaho until the mid- to late-Holocene. The recent arrival of the dominant tree species, Thuja plicata and Tsuga mertensiana, suggests that they likely did not persist in a refugium during the last glaciation. Instead, these species recently dispersed from coastal populations, but expansion into their interior distributions was likely limited by both climate and species competition in already established forests. During the late-Quaternary, the deposition of thick tephra layers (>20 cm) from the eruptions of Glacier Peak (ca. 13,400 years ago) and Mt. Mazama (ca. 7,600 years ago) also facilitated an abrupt and persistent change in vegetation in northern Idaho.

Made available in DSpace on 2014-06-11T19:30:13Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-02-21Bitstream added on 2014-06-13T19:39:32Z : No. of bitstreams: 1 tagliacollo_va_me_botib.pdf: 696657 bytes, checksum: 38fcfa7941eec57c79cee0e5fc106dc8 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / The subfamily Aphyocharacinae comprises the genera Aphyocharax, Prionobrama, Paragoniates, Phenagoniates, Leptagoniates, Xenagoniates, Rachoviscus, and Inpaichthys. This current arrangement based on a morphological analysis is congruent with most proposed morphological phylogenetic analyses, except for the inclusion of Rachoviscus and Inpaichthys which is tenuous and not always supported by data. In this current work the goal was to investigate the monophyly of the subfamily Aphyocharacinae and to recover relationships within it using molecular and morphological analyses. Using separate parsimony and Bayesian analyses of morphological, nuclear and mitochondrial genes, I recover new relationships within Aphyocharacinae. Independent analyses recovered similar topologies for molecular and morphologic datasets. Molecular based topologies showed common generic relationships: Aphyocharacinae, excluding the genus Rachoviscus and Inpaichthys, constitutes a monophyletic group. Moreover, Aphyocharacinae has two well–marked major branches. One composed by (Paragoniates (Phenagoniates (Leptagoniates+Xenagoniates))), while the other includes Aphyocharax and Prionobrama. Also, relationships among the genera were completely resolved and supported by strong statistical indexes. Based on molecular hypotheses, I had a specific monophyletic framework to conduct morphological analysis. This approach suggests that Aphyocharacidium sp. and Microschemobrycon cf. casiquiare are most probably the sister group of Aphyocharacinae. The morphological analysis conducted with 25 unweighted and unordered characters recovers one tree, resolved at generic–species level. A similar hypothesis found using molecular data is recovered with three well–marked... (Complete abstract click electronic access below)

New specimens of a small, advanced catarrhine primate from the Manchar Formation in Sind, southern Pakistan, are referred to Dionysopithecus sp. Their age is biochronologically estimated to be close to the early/middle Miocene boundary. Dionysopithecus is considered closely related to, and possibly congeneric with, Micropithecus from the East African early Miocene. The Manchar Dionysopithecus is among the earliest of Eurasian catarrhines. Catarrhines may have first emigrated from Afro-Arabia around 16·5 Ma, coincident with a major short-term eustatic sea level lowering event, and with the earliest records in South Asia of certain other African mammal groups. The first appearances in Eurasia of later, more advanced catarrhine lineages also appear to correlate with episodes of global sea level lowering.

The Appalachian Mountains are the source of the greatest diversity of salamanders in the world and the preservation and protection of this unique regional diversity are of important consideration. Salamanders can be subject to numerous diseases like ranaviruses and chytrid fungi, but an important factor to consider is other stressors that may affect salamander’s ability to recover from outbreaks. Human activity, be it habitat disruption or providing some vector for disease spread between populations and species, may have large impacts upon salamander population health. Identifying sites where salamanders and human activity are frequently overlapping in the territory could provide sites for future comparisons between more isolated populations and allow a better understanding of how humans may affect salamander populations. To identify sites where human activity may be common, a newt that is a quick colonizer of ephemeral pools, the Eastern Newt (Notophthalmus viridescens) was selected to observe. These sites were qualified upon their likeliness to support Notophthalmus viridescens individuals and other amphibian life cycles. Details such as forested canopy, ephemeral pools or stationary water ponds, leaf litter, and other amphibian activity were qualified by their presence or lack thereof. These sites were surveyed during fall thru winter, and the distance between these sites and closest human activity centers were measured in meters using Google Maps. Such activity centers could be classified as residences, public buildings, roads, trails, fences, or land disturbed by human activity like a construction site. Some sites will be purposely further away from human activity as for some comparison to more isolated sites. These sites should show that Notophthalmus viridescens can be found near human activity centers and therefore may be subject to be much influence from them.

No description available.