Life Sciences Commons^™

Homoploid Hybrid Speciation In A Rare Endemic Castilleja From Idaho (Castilleja Christii, Orobanchaceae), Danielle Leigh Clay

Boise State University Theses and Dissertations

Evidence to support the origins of a putative hybrid species with certainty must be determined using several lines of evidence: the presence of genetic additivity of parental marker alleles in a putative hybrid species, along with ecological or niche separation. Novel or transgressive morphological traits obtained through chromosomal rearrangements during hybridization may facilitate niche separation of the hybrid species from progenitor habitats. These evolutionary processes together enforce reproductive isolation and promote an independent evolutionary trajectory in hybrid species. By studying these evolutionary processes in putative hybrid species, researchers may identify hybrid species with confidence.

We employed multiple lines of evidence …

Natural Selection And Age-Related Variation In Morphology Of A Colonial Bird, Mary Bomberger Brown

School of Natural Resources: Dissertations, Theses, and Student Research

In May 1996, inclement weather led to the deaths of thousands of Cliff Swallows (Petrochelidon pyrrhonota) in Nebraska. Survivors had larger skeletons, shorter wings and tails, and less wing asymmetry than non-survivors. This population was followed for 10 years to study 1) whether natural selection events result in permanent microevolutionary changes, 2) if variation in climate affects the development of morphological traits, and 3) if morphological traits vary systematically with age.

Patterns in morphology exhibited by swallows following the selection event were studied by measuring yearling birds. Wing and middle tail lengths decreased, beak length and width increased, …

Determining The Composition Of The Dwelling Tubes Of Antarctic Pterobranchs, Lukasz J. Sewera

Honors Projects

Pterobranchs are a group of marine invertebrates within the Hemichordata, which share characteristics with both chordates and echinoderms. Pterobranchs live in colonies of secreted tubes, coenicia, which are composed of a gelatinous material of unknown composition. Visually, the tubes appear similar to the tunic of tunicates, a group of invertebrates within the Chordata. The nonproteinaceous tunic of tunicates is composed of cellulose, which is unusual. The goal of this study was to determine the composition of the pterobranch coenicium. Some aspects of pterobranch phylogeny are still unclear even after multiple molecular and morphological studies. Identification of any new shared characteristics …