The group known as the new world nine-primaried oscines is a large and diverse group containing about 10% of the living species of birds. The group is poorly known karyologically and phylogenetic relationships of some species within the group remain uncertain. In this paper, karyological data relating to the relationships of three species are presented. The data is also useful for exploring the nature of chromosomal evolution in birds. Two species of Parulinae were studied, with other warblers for comparison. Karyological data strongly supported removal of the Olive Warbler, Peucedramus taeniatus, from Parulinae. The Yellow-breasted Chat, Icteria virens, was found to be aberrant but properly a member of Parulinae. The genus Dendroica was found karyotypically conservative, with no differences between four species. The genus Vermivora was distinguished from other genera by large blocks of heterochromatin at the centromeres of most macrochromosomes. It appears that the Five-striped Sparrow, Amphispiza quinquestriata, is properly placed in its genus according to analysis of a data set that combined karyological and morphological data. This work strongly suggests that Chromosomal evolution is decoupled from the speciation process in Emberizidae. More intrageneric karyotypic variation was found within Emberizinae than has been previously reported from any bird taxon. There was a great deal of karyotypic rearrangement between species in Thraupinae and Cardinalinae. The rearrangements appear to be due to pericentric inversion. The heteromorphisms in the karyotypes of A. quinquestriata and Pipilo erythrophthalmus when combined with reports of heteromorphisms in other nine-primaried oscine species suggest this group has mechanisms to avoid meiotic irregularities usually associated with pericentric inversion. Further karyological studies of the nine-primaried oscines are required to improve our understanding of chromosomal evolution in the group.

A Simultaneous Photometer for Infrared and Visual light (hereafter SPIV) has been constructed. SPIV uses three dichroic filters to divide light from a common aperture in the telescope focal plane into four colors with bandpasses (in microns) of: 0.42 to 0.7 (V(B)); 0.7 to 0.95 (I(B)); 1.45 to 1.8 (H); 1.97 to 2.27 (K). The H and K bands are detected by liquid helium cooled InSb diodes. I(B) is detected by a helium cooled Si diode, and V(B) by an uncooled EMI 9658R photomultiplier tube. The instrument response function (IRF) including the effect of atmospheric transmission is shown. The maximum usable aperture size of 2 mm corresponds to 7 arcseconds on the Multiple Mirror Telescope and to 20 arcseconds on the UAO 61" and 90" telescopes. Information about the sky brightness is combined with the IRF to calculate the expected background noise. These calculations show SPIV should be background noise limited in all bands. Observations show this is true except for I(B), which is detector noise limited. The optical alignment of the four channels is shown to be satisfactory. The SPIV instrumental magnitude system is defined. Observations of 40 radio galaxies and 39 non-radio first ranked cluster galaxies with known redshifts ranging from 0.019 to 1.6 are reduced on this system, correcting for atmospheric extinction, reddening, and aperture. The transformation to standard magnitude systems is derived. The reduced V(B)-H, I(B)-H and H-K colors as a function of redshift are compared for the radio and non-radio galaxies using statistical tests. No convincing differences are found, with the possible exception of H-K in the z = 0.2 to 0.4 range. These colors are also compared to a "no evolution" prediction generated by redshifting a composite spectrum of nearby elliptical galaxies, and to evolutionary models from Bruzual (1981). Passively evolving models with little residual star formation and a galaxy formation epoch z(f) > 3 are slightly favored by H-K observations. These models predict about one magnitude brightening at H by a redshift of one. The I(B)-H color becomes redder with redshift much faster than the reddest model, and shows large scatter for z 3. Residual star formation models require an older universe than is allowed by qₒ = 0.5, Hₒ = 80 km/sec/Mpc to fit the red V(B)-H envelope at high redshift. Some galaxies show strong blueward deviations for z > 0.4. This behavior is most easily explained by episodes of star formation involving small fractions of the total number of stars. Because of the flatness of H-K and I(B)-H at high redshift, and the scatter in V(B)-H, determining redshifts > 0.4 from broadband colors will be difficult.

We study the influence of environment on galaxy evolution by focusing on two galaxy types known for their connection to dense environments, S0s and Brightest Cluster Galaxies (BCGs). Our goal is to identify the mechanisms responsible for the properties of galaxies in groups and clusters. We first examine the effects of environment on S0 formation over the past ~7 Gyr by tracing the increasing S0 fraction in clusters at two mass scales. We find the build-up of S0s driven by groups/clusters with velocity dispersions σ ≲ 750 km s⁻¹, suggesting mechanisms that operate most efficiently via slow encounters (e.g., mergers and tidal interactions) form S0s.With less-massive halos identified as the site for S0 formation, we test whether another route to S0 formation exists, not in isolated groups but rather in a system of four merging groups (SG1120). We place limits on how recent the S0s in that system could have formed, and finding no star formation, conclude they formed ≳ 1 Gyr prior to SG1120's current configuration, when they were in more isolated groups. We next explore cluster outskirts to constrain the number of infalling galaxies that need to be transformed and whether that process has already begun. We find the red fraction of infalling galaxies is elevated relative to the field, and that red galaxies are more clustered than blue ones, a signature of "pre-processing". We disentangle the relative strength of global versus local environment on galaxy transformation by comparing the correlation of red fraction with radius and local density. We find that both parameters are connected with the red fraction of galaxies. Finally, we measure the frequency of galaxies falling into the cluster that are bright enough to supplant the current BCG and compare the results to models. We find in ~ 85% of our clusters that the BCG is secure and remains in its priviledged state until z ~ 0.From these analyses, we find that intermediate density environments (groups and cluster outskirts) are the key site to forming S0 galaxies, and that BCGs, while not exclusively a cluster phenomenon, are well established by the redshifts we explore.

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