Browsing by Author "Nicholas M. Haddad, Committee Member"

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Factors Affecting Reproduction in the Red Wolf (Canis rufus).
(2009-07-20) Rabon, David Reid Jr.; Nicholas M. Haddad, Committee Member; Kenneth H. Pollock, Committee Member; Harold F. Heatwole, Committee Chair; Phillip D. Doerr, Committee Member
The endangered red wolf (Canis rufus) was preserved in captivity with just 14 founders following its planned extirpation in the wild. Longitudinal reproductive events were investigated to determine whether inbreeding, parental age, and breeding experience were factors in reproductive performance and fitness. A behavioral preference study using olfactory presentations of conspecific and congeneric social odors also was conducted to determine those factors that are important in the selection of mates. Over 30 years of managed breeding, the level of inbreeding in the captive population has increased, and litter size has declined. Inbreeding levels were lower in sires and dams that reproduced than in those that did not reproduce, but there was no difference in the level of inbreeding of actual and predicted litters. Litter size was negatively affected by offspring and paternal levels of inbreeding, but the effect of inbreeding on offspring survival was restricted to a positive influence. Younger wolves were more likely to reproduce, and were more likely to produce larger litters, than were older individuals. The age of the dam, but not the sire, had a significant negative effect on pup survival. Sires and dams that had prior experience in the production of offspring were more likely to reproduce again than were individuals without prior reproductive success, but prior sexual experience alone was not a factor in the production of offspring. Parental breeding experience had a significant negative effect on pup survival, but no apparent relationships with size or sex ratio of the litter. In general, females responded to the presentation of social odors of conspecific males more quickly than did males, and males responded more quickly to social odors of conspecific females than did females. There were no differences in the proportion of time males and females spent proximal to conspecific social odors. Males and females typically responded more quickly to and spent more time investigating social odors during the non-breeding season than during the breeding season. Species-specific responses to social odors were indeterminate.
Factors Limiting Growth in Astragalus Michauxii (Sandhills milk-vetch)
(2005-01-19) Weeks, Sonia Cooper; Jon M. Stucky, Committee Member; Nicholas M. Haddad, Committee Member; Robert J. Downs, Committee Member; Theodore H. Shear, Committee Chair
The seed germination-inducing mechanism of Astragalus michauxii and effects of heat and smoke on germination were explored. Seed germination is limited by a hard outer coat, a tough inner coat and possible germination-inhibitory substances in the embryo. Ninety-five percent seed germination was accomplished artificially by scarification in sulfuric acid, followed by piercing of the inner coat, and then leaching. Heat treatment between 80C and 86C resulted in 20% imbibition (p<.0001), 2% germination (p<.0031). All ungerminated, imbibed seeds were killed. Smoke did not promote germination. Effects of height, age, stem number and inter-specific competition on over-winter survival were studied A younger and an older group of plants were raised under controlled conditions and distributed among two 20x10-meter plots at Fort Bragg Military Reservation, NC, in the summer of 2002. Diameter and distances of each A. michauxii plant from the nearest oak sapling, pine tree, pine seedling, and wiregrass cluster were measured and a competition index (CI) calculated as ∑ [diameter of each competitor / (distance)2]. Fifty-nine percent of plants survived over-winter to the following spring. Logistic regression predicted height (p<.0001) and stem number (p=.0004) to increase over-winter survival. Effects of fire history and competition on vegetative and reproductive efforts and population persistence in A. michauxii were investigated among 48 sub-populations. Surveys of ground and canopy covers, growth and reproductive effort, along with fire history and population persistence data indicated that sub-populations with lower percentages of understory species covers other than pine, oak, and wiregrass were more likely to persist. Low regression coefficients for effects of competition and fire history indicate that a number of factors work together to impact growth and reproduction. A population demographic model determined the population to be declining. Management conservation efforts can best be directed by 1) collection and artificial seed germination and transplanting of seedlings into existing sub- populations, and 2) experimental testing of the impacts of varying fire regimes on habitat quality, plant growth and reproduction, and population growth and persistence.
Maximizing the Impact of Field Borders for Quail and Early-succession Songbirds: What?s the Best Design for Implementation?
(2007-12-09) Riddle, Jason; Nicholas M. Haddad, Committee Member; Christopher E. Moorman, Committee Chair; David T. Cobb, Committee Member; Stacy A. C. Nelson, Committee Member; Kenneth H. Pollock, Committee Member; Peter T. Bromley, Committee Member