Scholarship & Research

Permanent URI for this communityhttps://scholarworks.montana.edu/handle/1/1

Browse

Search Results

Now showing 1 - 10 of 18

Carry-over effects in partially migratory greater sage-grouse, southwest Montana
(Montana State University - Bozeman, College of Letters & Science, 2022) Waxe, James Andrew; Chairperson, Graduate Committee: Andrea Litt; This is a manuscript style paper that includes co-authored chapters.
Migration is a common natural phenomenon and an important life history strategy for many animal species. Migration allows individuals to accommodate changing environmental conditions, with the potential to increase survival or future reproduction. Many migratory species are subject to carry-over effects, where conditions experienced during one season or life stage influence subsequent life stages. Previous research has largely focused on evaluating the influence of carry-over effects on long-distance migrants, but less is known about these influences on shorter-distance migrants. During research in southwest Montana and southeast Idaho, we used VHF radio collars, red blood cells, stable isotopes, and morphometric information to understand the influence of carry-over effects on Greater Sage-grouse. In this population, some individuals migrate only short distances, while others may not migrate at all. We evaluated the influence of 1) different migration strategies and breeding locations on the body condition of females before breeding and 2) how variation in pre-breeding body condition influenced subsequent reproduction. We found non-migratory individuals were in better pre- breeding body condition than migrants during years with less winter precipitation. Similarly, individuals who experienced less precipitation during the breeding season also had higher pre- breeding body condition. Pre-breeding body condition positively influenced offspring weight early in the breeding season, but this relationship was less apparent later in the season. Our data suggest carry-over effects occur in this population of sage-grouse, but the magnitude of these effects was largely dependent on environmental conditions and timing of breeding. With increasing evidence of carry-over effects in sage-grouse populations, managers should broaden their conservation strategies to account for all life stages. Protecting a variety of winter habitat both near and distant from breeding areas will ensure the persistence and reproductive contribution of individuals with different migration strategies. Furthermore, protecting all known sage-grouse leks provides variation within a single population which allows for flexibility to respond in changing environments. Maintaining or enhancing landscape-level habitat heterogeneity supports variable life-history strategies and is critical for sage-grouse conservation.
Asynchrony between solitary bee emergence and flower availability reduces flower visitation rate and may affect offspring size
(Elsevier, 2021-08) Slominski, Anthony H.; Burkle, Laura A.
Climate change can disrupt plant-pollinator interactions when shifts in the timing of pollinator activity and flowering occur unequally (i.e., phenological asynchrony). Phenological asynchrony between spring-emerging solitary bees and spring-flowering plants may cause bees to experience food deprivation that can affect their reproductive success. However, the mechanisms underlying the effects of food deprivation on solitary bee reproduction remain unknown. We investigated 1) whether food deprivation caused by phenological asynchrony affects solitary bee reproduction by influencing female lifespan and/or visitation to flowers, and 2) the relationship between the magnitude of asynchrony and bee responses. We simulated phenological asynchrony by depriving emerged female Osmia cornifrons (a spring-active solitary bee species) of nectar and pollen for 0 to 16 days. Following asynchrony treatments, we used flight cages to monitor 1) post-treatment female lifespan, 2) flower visitation, and 3) reproduction (i.e., total offspring, offspring weight, sex ratio). We found that post-treatment female lifespan was not affected by phenological asynchrony treatments, but that flower visitation rate and offspring weight decreased as the magnitude of asynchrony increased. Due to low offspring production and a lack of female offspring across treatments, we were unable to assess the effects of phenological asynchrony on total offspring produced or sex ratio. Findings suggest that post-emergence food deprivation caused by phenological asynchrony may affect offspring size by influencing nest-provisioning rates. In solitary bees, body size influences wintering survival, fecundity, and mating success. Thus, phenological asynchrony may have consequences for solitary bee populations that stem from reduced flower visitation rates, and these consequences may increase as the magnitude of asynchrony increases. Because many wild flowering plants and crops rely on pollination services provided by bees for reproductive success, bee responses to phenological asynchrony may also affect wild plant biodiversity and crop yields.
Relating the reproductive performance of westslope cutthroat trout to trait specialization to screen for artificial selection vulnerability in a conservation hatchery
(Montana State University - Bozeman, College of Letters & Science, 2022) Preul-Stimetz, Taylor Nicole; Chairperson, Graduate Committee: Christine Verhille
To mitigate westslope cutthroat trout (WCT; Oncorhynchus clarkii lewisi) declines, Montana Fish, Wildlife, & Parks carries out large scale restorations, including wild-origin stocking efforts from conservation hatcheries. Although hatcheries have made progress in limiting the effects of artificial selection on stocked populations, concerns remain that rearing practices inadvertently reduce the diversity propagated into the wild. The objective of this research was to identify traits of WCT driving poor survival or reproduction in a hatchery, allowing managers to reduce artificial selection by screening for fish requiring alternative rearing. In Chapter 1, I repeatedly measured 18 behavior, morphology, and health traits from hatchery intake (July 2019) to spawn (June 2021). I identified traits with low within- relative to between-individual variation as traits likely to be indicative of specialization. As specialists tend to maximize performance under a narrow range of conditions, they may be vulnerable to artificial selection within hatcheries. In Chapter 2, I tested whether the specialized traits identified in Chapter 1, growth rate, or age at hatchery intake of individual WCT could predict survival or reproduction. In Chapter 1, I identified nine specialized (relative condition, weighted health index, health index, body shape, energetic reserves, latency, and upper jaw, lower jaw, and anal fin residual length) traits. I hypothesized these traits would predict later survival or reproductive performance. In Chapter 2, I identified October 2019 daily growth rate in weight and every replicate length measurement after October 2019 to strongly predict total ovulated eggs and total number of hatch embryos produced by females. However, among individual variation in the median percent hatch embryos was not explained by maternal size. Male gamete quality and fertilization success was consistently high, and I found no biologically significant predictors of reproductive performance for males. I also found no predictors of survival for males or females. Despite high total ovulated eggs and total hatch embryo success for females, variable female median percent hatch embryos suggests that quality of ovulated eggs is driving current limitations to WCT hatchery reproduction. I recommend further investigation into impacts of rearing stressors and post-ovulatory aging on female WCT and their reproductive performance.
Reproductive biology and phenology of western pearlshell mussels in Montana
(Montana State University - Bozeman, College of Letters & Science, 2022) Cook, Kristen Ann; Chairperson, Graduate Committee: Alexander V. Zale
The Western Pearlshell mussel is the only native freshwater mussel inhabiting trout streams of western Montana; it has been designated a state Species of Concern because of declines in abundance and distribution. Conservation of Western Pearlshells in Montana will require fundamental information on their reproduction and life-history traits that is currently lacking. We therefore estimated the age and length at sexual maturity and incidence of hermaphroditism in mussels using histology. We determined the timing of reproductive events (spawning, brooding, embryogenesis, larval release, and larval infestation of hosts) and their relationship to temperature by collecting gonadal and marsupial biopsies to identify gamete presence and embryo developmental stages, visually identifying brooding mussels, and examining captured fish for the presence of mussel larvae. We identified the hosts of Western Pearlshells in nature by quantifying the probability of infestation and infestation intensities among salmonid species. Mussels reached sexual maturity at an estimated 34 mm in length and 11.5 years of age. Of 31 mature mussels examined histologically, all but one were gonadal hermaphrodites. The reproductive phenology of Montana Western Pearlshells differed among populations and years. Mussel populations brooded for about 24 to 39 days in May and June. Embryogenesis was synchronous among individuals in all populations except one and was about two to three weeks in duration. The larval infestation period generally occurred in June and July and was 47 to 71 days in duration. Some larvae grew > 400% in length before leaving the host. Gonadal recrudescence was rapid whereby mussels possessed mature or nearly mature gametes by early autumn. Both photoperiod and temperature appear to influence the timing of reproductive events. Native Westslope Cutthroat Trout and nonnative Brook Trout were the most susceptible fish species to infestation of Western Pearlshell larvae. Nonnative Brown Trout were moderately susceptible to infestation in the Flint-Rock watershed. Nonnative Rainbow Trout and native Mountain Whitefish were least likely to be infested with mussel larvae. Our findings will inform future conservation and propagation efforts of Western Pearlshells in Montana.
Reproductive and juvenile ecology of mountain whitefish in the upper Green River, Wyoming
(Montana State University - Bozeman, College of Letters & Science, 2022) Brown, Colter Davis; Chairperson, Graduate Committee: Christopher S. Guy
Mountain Whitefish Prosopium williamsoni are a salmonid native to the northern Rocky Mountains that has experienced declines in population abundance in rivers throughout Idaho, Colorado, Wyoming, and Montana. Problems with recruitment are suspected, but often the specific mechanisms causing population declines are unknown. Our approach to better understand the mechanisms that influence Mountain Whitefish population dynamics was to compare population characteristics between the Green River, Wyoming and the Madison River, Montana populations. Boyer et al. (2017a) conducted an extensive study on the movement and reproductive ecology of Mountain Whitefish in the Madison River, and we used this study as a template to make direct comparisons between the populations. Our primary research questions were 1) what is the age and length at first maturity, spawning periodicity, fecundity, and age structure of Mountain Whitefish, 2) what is the spatial and temporal distribution of Mountain Whitefish through their spawning period, and what influence do abiotic factors have on spawning and movement, and 3) what is the spatial distribution and habitat use of age-0 Mountain Whitefish? We collected otoliths and gonadal samples from 127 Mountain Whitefish in the Green River, implanted 100 fish with radio transmitters and tracked them from September 1 to early November in 2019 and 2020, determined spawning period and locations using egg mats, kick netting, and angling, and sampled age-0 Mountain Whitefish using a beach seine in slow-water habitats. The geographic separation and difference in hydrogeomorphic conditions between the systems allowed us to form generalizations about Mountain Whitefish in the Intermountain West. We found Mountain Whitefish in both systems mature between ages 2 and 4, primarily spawn annually, have a similar relative fecundity, spawning movements vary, males begin movement prior to females, and age-0 fish drift downstream of spawning locations and use slow-water silt-laden habitats after hatching. The main disparities between systems were that in the Green River water temperature was more suitable for embryo development, and age structure was more uniform and older. This research enhanced our understanding of Mountain Whitefish reproductive and juvenile ecology and provided evidence for factors that may influence recruitment of Mountain Whitefish.
Reproductive ecology of hatchery-origin pallid sturgeon upstream of Fort Peck Reservoir, Montana
(Montana State University - Bozeman, College of Letters & Science, 2020) Cox, Tanner Lewis; Chairperson, Graduate Committee: Christopher S. Guy; Christopher S. Guy and Molly A. H. Webb were co-authors of the article, 'First maturity, spawning periodicity, and follicular atresia of hatchery-origin pallid sturgeon in the Missouri River above Fort Peck Reservoir, Montana' submitted to the journal 'Journal of applied ichthyology' which is contained within this thesis.; Christopher S. Guy and Molly A. H. Webb were co-authors of the article, 'Reproductive ecology and behavior of hatchery-origin pallid sturgeon in the Missouri River above Fort Peck Reservoir, Montana' submitted to the journal 'Journal of applied ichthyology' which is contained within this thesis.
Conservation propagation of pallid sturgeon above Fort Peck Reservoir has successfully recruited a new generation of spawning-capable pallid sturgeon to a location that would otherwise have fewer than 30 remaining. Successful recovery of pallid sturgeon will now rely on spawning in locations that provide adequate drift distance for larvae to recruit. Prior to this study, all reproductively-active female pallid sturgeon underwent ovarian follicular atresia. The reasons for and prevalence of ovarian follicular atresia were unclear, spawning periodicity of females remained undescribed, and remaining prepubescent fish indicated that age- and size-at-first maturity would vary more than currently described. Furthermore, spawning location, spawning-related interactions among conspecifics, and substrate composition at spawning locations remained undescribed. We used data on reproductive status and location to describe age- and size-at-first maturity, the prevalence of ovarian follicular atresia during first gametogenic cycles, spawning periodicity for female and male pallid sturgeon, where spawning occurs, if spawning locations are related to discharge, if substrate characteristics at the spawning locations were similar to other river reaches, and if female, male, and atretic female pallid sturgeon use the river similarly. Pallid sturgeon matured at older ages and larger sizes than described for other populations with females maturing at 18 years old and males at 15; however, prepubescent pallid sturgeon as old as 20 were documented. During the presumed-first gametogenic cycle, 62.5% of female pallid sturgeon underwent follicular atresia. Females had biennial reproductive cycles, and males had annual and biennial reproductive cycles. Reproductively-active male and female pallid sturgeon were found in similar locations, while locations of atretic female pallid sturgeon varied. The furthest upstream locations of pallid sturgeon including locations in the Marias River occurred during 2018 when discharge was at an unprecedented high. Spawning occurred in locations less than 131 km from the river-reservoir transition zone, which does not provide adequate drift-distance for larvae. Altering discharge and water temperature at Tiber Dam to mimic observed values in 2018 may increase use of the Marias River by pallid sturgeon during spawning, which would provide adequate drift distance to larvae.
The effects of climate-warming on solitary bees and their interactions with plants
(Montana State University - Bozeman, College of Letters & Science, 2019) Slominski, Anthony Hayden; Chairperson, Graduate Committee: Laura Burkle and Jia Hu (co-chair)
The ecological consequences of anthropogenic climate-warming remain poorly understood for pollinators. In order to better understand these consequences, and thus the consequences of climate-warming for pollination services, we must determine how pollinator life histories mediate responses to climate-warming. To help address these research needs, we conducted three studies. First, we used field-collected solitary bee species (i.e., Osmia spp. and Megachile spp.) to investigate how overwintering life stage (i.e., adult versus prepupae), body size, and sex influenced solitary bee survival, weight loss prior to emerging, and timing of emergence in response to manipulated seasonal temperature and the durations of seasons. Second, we manipulated the amount of asynchrony (days) between female solitary bee emergence and flowering periods. We used a mesocosm-based experimental design to investigate the effects of phenological asynchrony on the female lifespan, female interaction rates with flowers, and reproductive success. In a third study, we manipulated the amount of phenological difference between conspecific male and female solitary bees (i.e., the degree of protandry; males emerging prior to females), and investigated the influence of sex-specific phenological responses to temperature on male-female interactions and reproductive success. Our main findings and subsequent conclusions were that i) compared to bees that overwinter as prepupae, patterns in weight loss prior to emergence, adult longevity, and timing of emergence suggested that post-emergence fitness in adult-wintering bees may decrease under climate-warming as a result of increased energy depletion at the time of emergence, increasing asynchrony with flowering periods, and sex-specific phenological responses, ii) asynchrony between a spring-active female solitary bee species (i.e., Osmia cornifrons) and flowering periods caused reductions in offspring body size and reduced interaction rates between females and flowers, which could have consequences for both bee and plant reproductive success, and iii) when the degree of protandry was either reduced or increased from an intermediate level, the probability of female offspring production tended to decrease. This suggests that changes in the degree of protandry may influence the fitness tradeoffs associated with protandry, resulting in consequences for current and future solitary bee reproductive success.
Description of the reproductive structure, size, growth, and condition of hatchery-origin white sturgeon in the lower Columbia River, British Columbia, Canada
(Montana State University - Bozeman, College of Letters & Science, 2020) Maskill, Paige Anne Camas; Chairperson, Graduate Committee: Christopher S. Guy; James A. Crossman, Christopher S. Guy and Molly A. H. Webb were co-authors of the article, 'Describing the reproductive structure of the hatchery-origin population of white sturgeon in the lower Columbia River, British Columbia, Canada' which is contained within this thesis.
Conservation aquaculture has been successful in preventing extirpation of endangered white sturgeon Acipenser transmontanus in the lower Columbia River (LCR), Canada. The goals of this project were to 1) determine if the hatchery-origin (HO) population has reached puberty as many fish are of an age and body size to begin contributing to spawning and 2) assess the size, absolute growth rate (AGR), and relative condition factor (Kn) of the population. The reproductive structure (sex and stage of maturity) of the HO population was assessed using multiple tools (gonadal biopsy analyzed histologically, ultrasound, endoscopy, and plasma sex steroids). The accuracy of each tool was determined by comparing the assigned sex to the true sex determined by histological analysis of a gonadal biopsy. A subobjective was to determine whether gonadal development was homogenous (assessed in fish captured in LCR and Lake Roosevelt, WA, USA). All fish assessed were pre-meiotic males (n=158) or pre-vitellogenic females (n=174) and had yet to reach puberty. Endoscopy and gonadal biopsy analyzed histologically were the most accurate tools with accuracies > 97%. Gonadal development was homogenous in females but 38% of the males exhibited non-homogenous testicular development, with a few precocious cysts that contained germ cells in an advanced stage of development compared to the predominant phase seen throughout the biopsy. The size, AGR, and Kn were compared among sex, age, and river zone. While the mean Kn indicated that the HO white sturgeon were in average condition relative to all HO fish within the LCR, they were lower in condition compared to the full transboundary population (Canada and USA). This reflects a difference in the environmental or physiological conditions of the fish in the LCR and those captured throughout the transboundary reach. Results of this work will be important to determine the reproductive dynamics of the hatchery-origin population over time (e.g., age and size at puberty, sex ratio), and specifically when these fish will begin spawning in the wild. Additionally, this information will help to develop other standardized monitoring programs which can track the reproductive structure of a population over time using tools with known accuracy rates.
Influence of thermal regime on the life histories and production of Rocky Mountain aquatic insects
(Montana State University - Bozeman, College of Letters & Science, 2019) McCarty, Jennifer Denise; Chairperson, Graduate Committee: Wyatt F. Cross
Life history traits of aquatic insect taxa such as metabolism, terminal body size, and fecundity vary along natural thermal gradients. Body size, in particular, is expected to respond to temperature and may have important consequences for fecundity and the production of insects. The Thermal Equilibrium Hypothesis (TEH) predicts that aquatic insect taxa are most abundant at an intermediate 'optimal' temperature where life history traits such as terminal body size and reproductive potential are maximized, i.e., the thermal 'optimum'. A competing hypothesis, the Temperature Size Rule (TSR), predicts that individuals developing at the coldest temperatures in their range will grow more slowly, but attain the largest body sizes and therefore exhibit greater fecundity than individuals growing at warmer temperatures. Implicit in both of these theories is that population-level production, a measure of population 'success', will be greatest where terminal body size and fecundity are maximized. Few studies have investigated the TEH in the field, and none have measured the relationship between production and other life history traits in the context of these theories. Our study focused on three common Rocky Mountain aquatic insect taxa: Drunella doddsii, Hydropsyche cockerelli, and Ephemeralla infrequens. We quantified the influence of thermal regime on growth rates, terminal body size, reproductive potential, and population-level biomass and production, all of which potentially limit the longitudinal distribution and success of these taxa. We found that growth varied strongly with season and site, leading to significant variation in the timing of growth and terminal body size. Reproductive potential was negatively associated with mean annual temperature as predicted by the TSR. Unexpectedly, reproductive potential was not always correlated with terminal body size. Population density, biomass, and secondary production were generally positively correlated with terminal body size for D. doddsii and H. cockerelli, as expected from both predictive models. In contrast, these relationships were not as consistent for E. infrequens. Our findings provide new insight as to how thermal variation influences the ecology of aquatic insects in the context of the TEH and TSR. Our results should be valuable for predicting population and community responses to ongoing changes in climate.
Impacts of weather, habitat, and reproduction on the survival and productivity of wild turkeys in the northern Black Hills, South Dakota
(Montana State University - Bozeman, College of Letters & Science, 2019) Yarnall, Michael James; Chairperson, Graduate Committee: Andrea Litt; Andrea R. Litt, Chad P. Lehman and Jay J. Rotella were co-authors of the article, 'Precipitation and reproductive effort combine to alter survival of wild turkey hens in the northern Black Hills, SD' submitted to the journal 'Journal of wildlife management' which is contained within this thesis.; Andrea R. Litt, Chad P. Lehman and Jay J. Rotella were co-authors of the article, 'Impacts of weather on reproductive productivity of wild turkeys in the northern Black Hills, SD' submitted to the journal 'Journal of wildlife management' which is contained within this thesis.
The study of population ecology is motivated by a desire to understand variation in the factors that drive wildlife population dynamics. Robust vital rate estimates are crucial for effective wildlife conservation and management, particularly for at-risk or harvested species. In avian populations, the survival of females, nests, and young are important drivers of population growth, although the relative importance of each rate can differ among species. Annual and regional variation in vital rates within species is common; further, local climatic and habitat conditions may influence population dynamics. During 2016 - 2018, we used radio telemetry to study the impacts of weather and habitat conditions on the survival and productivity of Merriam's wild turkeys (Meleagris gallopavo merriami) in the northern Black Hills of South Dakota. Specifically, we quantified the impacts of 1) precipitation and reproductive effort on hen survival, 2) precipitation and habitat conditions on nest survival, and 3) precipitation and temperature on early poult survival. Precipitation reduced the survival of hens and nests, although the magnitude depended on the hen's incubation status or the vegetation characteristics at the nest site. Based on precipitation data from 2017, the estimated annual survival rate for a hen that did not incubate was 0.535 (SE = 0.038), whereas that and for a hen that incubated for 26 days was 0.436 (SE = 0.054). The probability that a nest would survive from initiation to hatching for a nest initiated by an adult hen on the median date of nest incubation in 2017 was estimated to be 0.432 (SE = 0.084). The estimated probability that a poult would survive from hatching to 4 weeks of age was 0.387 (SE = 0.061). Our results clearly demonstrate a negative cost of reproduction, as predicted by life-history theory, and show that hens and nests in this ecosystem are more vulnerable to predation during or immediately following rainfall, as predicted by the moisture-facilitated nest-predation hypothesis. Survival and productivity of turkeys was lower in our study area than in other portions of the Black Hills; we recommend that managers take steps to limit human-induced hen mortality of this important game species.

Scholarship & Research

Browse

Filters

Settings

Sort By

Results per page

Search Results