Fourwing saltbush (Atriplex canescens) was seeded in 80 -inch wide water harvesting microcatchments on retired farmland west of Tucson. Eight months after planting the plots that had received one establishment irrigation and weeding had significantly more cover than the unirrigated and unweeded treatments. The percent cover of the uninigated /weeded and irrigated /unweeded treatments was not significantly different. Uninigated and unweeded plots had virtually no cover of saltbush. It appears that establishing saltbush in microcatchments of this size is not feasible without either an establishment irrigation or weed control.

Sprouting response of Quercus emoryi and Quercus arizonica was studied following a May, 1987 wildfire on the Audubon Society Research Ranch Preserve in Santa Cruz, Co., AZ. Sprouting response of oaks was measured as total number and density of sprouts by species and diameter class. Thirty-five of the 109 trees examined (32%) sprouted in response to the fire, including 30.5% of all Q. emoryi and 36.4% of all Q. arizonica. In both species, small diameter (10 cm) trees are more likely to sprout than those larger than 10 cm. Quercus emoryi trends toward producing more sprouts/tree than Q. arizonica (avg. of 14.03 sprouts to 6.87 sprouts). Among all sprouters, however, there is no difference in the number of sprouts produced by trees in the two size classes. Sprout density is greater in Q. emoryi at 3.58 sprouts/cm. Q. arizonica averages 0.89 sprouts/cm. In all sprouters, density is greater in smaller stems (4.17 sprouts/cm) compared with 0.71 sprouts/cm in the larger size class.

Germination responses of P.I. 237110 and 'Ganada' yellow bluestem (Bothriochloa ischaemum (L.) Keng.) were compared in four experiments. P.I. 237110 had the highest total germination for all seed conditioning treatments. At the lowest temperature (15.6°C) P.I. 237110 did not germinate and Ganada had a low total germination. P.I. 237110 and Ganada require high (>20°C) incubation temperatures for optimum germination. Seed conditioning treatments did not significantly increase total germination for P.I. 237110 or Ganada. The caryopsis treatment gave the highest percent germination for all germplasm except Ganada. P.I. 237110 had the fastest time to 50% germination for all seed conditioning treatments. Seed conditioning did not significantly affect time to 50% germination for P.I. 237110 or Ganada. Ganada had significantly higher respiration rates than P.I. 237110 at 0 and -0.4 MPa but not at -0.8 and -1.2 MPa. Respiration rates for both germplasm decreased as osmotic concentrations became more negative.

I determined if Sonoran pronghorn (Antilocapra americana sonoriensis) could meet water and mineral requirements through consumption of forage. I sampled vegetation using dry weight rank and comparative yield methods in southwestern Arizona from June 1995 to May 1996 to determine preformed water, nutrient content, mineral content, and vegetation abundance. Water and nutrient content of plants varied between 2 sites and among 5 seasons (P ≤ 0.05). Plants consumed by pronghorn were higher in moisture and nutrients (P ≤ 0.05) than non-forage species. I constructed a model for Sonoran pronghorn diet based on field data. I used the model to describe dietary intake. Water intake predicted by diet models ranged from 1.1 to 6.1 L/animal/day; often exceeding predicted total water requirements (1.8-3.4 L/animal/day). Models predicted that forage provided adequate water for pronghorn during 5 seasons at 1 of 2 study sites and deficiencies for 5 of 11 minerals at both study sites.

I compared vegetation features and rodent communities between manipulated and non-manipulated ranges in southeastern Arizona during summers 1996 and 1997. I also examined the effect of burying traps to determine if this procedure altered trap sensitivity. I used two-way analysis of variance or paired t-tests for all comparisons and identified relationships between rodents and vegetation features with linear regression. There was no difference (P ) in rodent species richness or population size between mechanically treated and reference areas. Rodent species richness and population size were greater on ungrazed compared to grazed areas (P ), but there was no difference in rodent diversity (P = 0.13). Prescribed fire did not have an obvious impact on rodent species richness or population size, though there seemed to be an increase in kangaroo rats following the burn. Buried traps may have demonstrated a reduction in sensitivity because I caught fewer animals in those traps compared to non-buried traps (P = 0.087).

Historically, wildfires in mixed conifer forests of Southwestern sky islands were frequent events. Dendrochronological methods were used to reconstruct fire regimes and stand age structures in the Huachuca Mountains of Southeastern Arizona. Pre-settlement (i.e., before ca. 1870) fire intervals ranged from 4 to 10 years, with many fires spreading over the entire sample area. Stand age distributions show an increase in more shade-tolerant tree species. Although ponderosa pine is still the dominant overstory tree species, recent recruitment is predominantly southwestern white pine and Douglas-fir. Establishment of Ft. Huachuca in 1877 was a precursor to extensive use of timber, mineral, range and water resources in the Huachuca Mountains. The fire regime was altered at this time, with only one subsequent widespread surface fire recorded in 1899. Settlement era land-use practices may be responsible for changes in stand structure and composition.

Masked bobwhites used sites with more structural diversity than what was available on the Buenos Aires National Wildlife Refuge during 1994-96. Selected habitat variables that adequately predicted habitat use by masked bobwhites included percent herbaceous canopy cover, structure at 15 cm and 2 m, forb richness, and season. Masked bobwhite used more structural diversity than Gambel's and scaled quail. Gambel's quail had broader habitat tolerances than either masked bobwhite or scaled quail. Selected habitat variables that revealed differences among masked bobwhites, Gambel's quail, and scaled quail included percent woody canopy cover, structure at 15 cm, forb richness, and season. A historic perspective revealed that masked bobwhites used sacaton grasses that grew along the floodplains as important escape cover. I believe that we need to restore the integrity of the grassland ecosystems including the floodplain if we are to recover masked bobwhite quail.

I examined trends in relative abundance and species richness of breeding and wintering grassland birds before (1996) and after (1997, 1998) a spring prescribed burn in a mesquite-dominated desert grassland at Buenos Aires National Wildlife Refuge, Arizona. The burn was moderate in intensity, patchy in extent, and affected ground cover more strongly than shrub cover, smaller shrubs more strongly than larger shrubs, and killed 1% of velvet mesquite (Prosopis velutina). Species richness of breeding birds decreased in the first year post-burn. Of breeding species, black-throated sparrows (Amphispiza bilineata) and mourning doves (Zenaida macroura) increased; whereas Botteri's sparrows (Aimophila botterii), Cassin's sparrows (Aimophila cassinii), and pyrrhuloxias (Cardinalus sinuatus) decreased in relative abundance. Breeding species characterized as not shrub-dependent exhibited changes that were more pronounced than those for shrub-dependent species. Of wintering birds, ladder-backed woodpeckers (Picoides scalaris) and vesper sparrows (Pooecetes gramineus) increased, and cactus wrens (Campylorhynchus brunneicapillus) decreased in relative abundance.

I determined density and habitat use of desert mule deer (Odocoileus hemionus crooki) on the Buenos Aires National Wildlife Refuge, a semidesert grassland in southeastern Arizona, in 1996. I observed 219 groups of deer; densities varied from 0.9 ± 0.3 (SE) deer/km² in summer to 2.5 ± 1.3 in winter. Herd size varied from 1.5 ± 0.1 deer/group in summer to 9.7 ± 2.0 in winter. Density of females was greater than males (0.9 ± 0.3 and 0.03 ± 0.04, respectively). Mule deer used subshrub-grass more in summer (χ² = 54.8, 6 df, P < 0.0001) and Russian thistle (Sallsola kali) less and cactus more in autumn (χ² = 60.2, 6 df, P < 0.0001) than expected. Deer used mesquite (Prosopis velutina) less than expected, which may have been due to the difficulty of observing deer in dense cover. In general, the mule deer population was widespread, had a high proportion of females, and used vegetation associations as available.

Despite over seven decades of speciation research and 25 years of phylogeographic studies, a comprehensive understanding of mechanisms that generate biological species remains elusive. In temperate zones, the pervasiveness of range fragmentation and subsequent range expansions suggests that secondary contact between diverging lineages may be important in the evolution of species. Thus, such contact zones provide compelling opportunities to investigate evolutionary processes, particularly the roles of geographical isolation in initiating, and indirect selection against hybrids in completing (reinforcement), the evolution of reproductive isolation and speciation. The spring peeper (Pseudacris crucifer) has six well-supported mitochondrial lineages many of which are now in secondary contact. Here I investigate the evolutionary consequences of secondary contact of two such lineages (Eastern and Interior) in Southwestern Ontario using genetic, morphological, acoustical, experimental, and behavioural evidence to show accentuated divergence of the mate recognition system in sympatry. Mitochondrial and microsatellite data distinguish these two lineages but also show ongoing hybridization. Bayesian assignment tests and cline analysis imply asymmetrical introgression of Eastern lineage nuclear markers into Interior populations. Male calls are divergent between Eastern and Interior allopatric populations and show asymmetrical reproductive character displacement in sympatry. Female preference of pure lineage individuals is also exaggerated in sympatry, with hybrids showing intermediate traits and preference. I suggest that these patterns are most consistent with secondary reinforcement. I assessed levels of post-zygotic isolation between the Eastern and Interior lineages using a laboratory hybridization experiment. Hybrid tadpoles showed equal to or greater fitness than their pure lineage counterparts, but this may be countered through competition. More deformities and developmental anomalies in hybrid tadpoles further suggest post-zygotic isolation. Despite evidence for pre-mating isolation between the two lineages, isolation appears incomplete (i.e. hybridization is ongoing). I hypothesize that potentially less attractive hybrids may circumvent female choice by adopting satellite behaviour. Although mating tactics are related to body size, genetic status may play a role. I show that pure Eastern males almost always engage in calling, while hybrids adopt a satellite tactic. An absence of assortative mating, despite evidence of female preference, suggests successful satellite interception possibly facilitating introgression. / Thesis (Ph.D, Biology) -- Queen's University, 2013-03-04 16:01:33.892