Population dynamics of northern white-tailed deer during mild winters: evidence of regulation by food competition

2000 ◽  
Vol 78 (5) ◽  
pp. 764-776 ◽  
Author(s):  
André Dumont ◽  
Michel Crête ◽  
Jean-Pierre Ouellet ◽  
Jean Huot ◽  
Jean Lamoureux
Keyword(s):  
Population Dynamics ◽  
Survival Rates ◽  
Food Competition ◽  
Finite Rate ◽  
Mortality Pattern ◽  
Rate Of Increase ◽  
Wintering Area ◽  
Probability Of Death ◽  
Low Levels ◽  
Two Populations

We studied white-tailed deer (Odocoileus virginianus borealis) at the northeastern limit of their range after their density had decreased as a result of harsh winters aggravated by coyote predation. We compared two populations wintering in adjacent areas. In the Lac Témiscouata wintering area (LTWA), deer and browse density averaged 10 animals/km2 and 127 000 deciduous twigs/ha compared with 20 deer/km2 and 68 000 twigs/ha, respectively, at the Pohénégamook wintering area (PWA). For 75 radio-collared deer, the probability of death was highest during the short spring migration and remained elevated in winter, whereas fewer deaths occurred in summer and none during autumn migration. PWA deer had a higher mortality rate than did LTWA animals and died mostly in winter, from predation, starvation, and collision equally. Based on observed survival rates, we estimated that the finite rate of increase averaged [Formula: see text]1.25 and [Formula: see text]1.00 for LTWA and PWA populations, respectively. At PWA, we examined 129 carcasses to determine the mortality pattern of deer. Among adults, we did not detect significant differences related to sex. Starvation and predation affected more fawns and old deer than prime animals, whereas collision appeared to be nonselective. Most cases of starvation occurred after the beginning of March, when body reserves dropped to low levels. We conclude that competition for winter forage regulated PWA deer during the study.

Biotic interactions and the population dynamics of the long-lived columnar cactus Neobuxbaumia tetetzo in the Tehuacán Valley, Mexico

1999 ◽  
Vol 77 (2) ◽  
pp. 203-208 ◽  
Author(s):  
Héctor Godínez-Alvarez ◽  
Alfonso Valiente-Banuet ◽  
Leopoldo Valiente Banuet
Keyword(s):  
Population Dynamics ◽  
Matrix Models ◽  
Biotic Interactions ◽  
Positive Interactions ◽  
Elasticity Analysis ◽  
Finite Rate ◽  
Tehuacán Valley ◽  
Columnar Cactus ◽  
Tehuacan Valley ◽  
Rate Of Increase

The giant columnar cactus Neobuxbaumia tetetzo (Coulter) Backeberg is the dominant species of a vegetation type locally called "tetechera" that occupies ca. 400 km2 in the Tehuacán Valley. As a way to analyse the role of biotic interactions on the population dynamics of this species, we conducted an elasticity analysis, using matrix models elaborated from field data, to determine the finite rate of increase and the critical stages of the life cycle that were related to the biotic interactions occurring during these stages. Although the estimated finite rate of increase did not differ from unity there were significant differences between the actual and predicted size distributions. Elasticity analysis showed that survivorship was the most important life-history parameter to the finite rate of increase. Because survivorship depends on the presence of nurse plants, our results emphasise the importance of positive interactions on the population dynamics of long-lived columnar cacti.Key words: biotic interactions, Cactaceae, deserts, matrix models, population dynamics.

Evaluation of an experimental wolf reduction and its impact on deer in Papineau-Labelle Reserve, Quebec

1992 ◽  
Vol 70 (8) ◽  
pp. 1595-1603 ◽  
Author(s):  
François Potvin ◽  
Hélène Jolicoeur ◽  
Laurier Breton ◽  
Rolland Lemieux
Keyword(s):  
Reduction Rate ◽  
Management Tool ◽  
Finite Rate ◽  
Rate Of Increase ◽  
Wintering Area ◽  
Current Context ◽  
The Mean ◽  
Four Blocks

From 1984 to 1986, 56 wolves were removed by aerial shooting from two reduction blocks in Papineau-Labelle Reserve: the mean reduction rate was 71% in RB1 and 40% in RB2, compared with 17 and 9% for two untreated blocks (UB1 and UB2). Corresponding mean wolf densities in the four blocks at the end of winter were 0.6, 1.2, 1.6, and 1.7 wolves/100 km2, respectively. Each year, wolf numbers returned to their former level in the subsequent winter in RB1, mainly through immigration. Three blocks were each associated with a large deer wintering area containing 1400–1700 animals before the wolf reduction. The deer yard in RB1 reached a population of 4200 deer, a 1.32% finite rate of increase per year, compared with annual rates of 1.15–1.18% in UB1 and RB2. The harvest of bucks was not affected by the wolf reduction. The number of fawns per 100 does in the harvest was higher in RB1 than in UB1 in 1985 and 1986. We do not recommend wolf reduction as a management tool in the current context, as deer numbers increased markedly, even where no control was applied, as a consequence of mild winters.

Persistence of giants: population dynamics of the limpet Scutellastra laticostata on rocky shores in Western Australia

2020 ◽  
Vol 646 ◽  
pp. 79-92
Author(s):  
RE Scheibling ◽  
R Black
Keyword(s):  
Population Dynamics ◽  
Western Australia ◽  
Size Structure ◽  
Survival Rates ◽  
Maximum Size ◽  
High Rate ◽  
Adult Survival ◽  
Rocky Shores ◽  
Adult Size ◽  
Decadal Time Scale

Population dynamics and life history traits of the ‘giant’ limpet Scutellastra laticostata on intertidal limestone platforms at Rottnest Island, Western Australia, were recorded by interannual (January/February) monitoring of limpet density and size structure, and relocation of marked individuals, at 3 locations over periods of 13-16 yr between 1993 and 2020. Limpet densities ranged from 4 to 9 ind. m-2 on wave-swept seaward margins of platforms at 2 locations and on a rocky notch at the landward margin of the platform at a third. Juvenile recruits (25-55 mm shell length) were present each year, usually at low densities (<1 m-2), but localized pulses of recruitment occurred in some years. Annual survival rates of marked limpets varied among sites and cohorts, ranging from 0.42 yr-1 at the notch to 0.79 and 0.87 yr-1 on the platforms. A mass mortality of limpets on the platforms occurred in 2003, likely mediated by thermal stress during daytime low tides, coincident with high air temperatures and calm seas. Juveniles grew rapidly to adult size within 2 yr. Asymptotic size (L∞, von Bertalanffy growth model) ranged from 89 to 97 mm, and maximum size from 100 to 113 mm, on platforms. Growth rate and maximum size were lower on the notch. Our empirical observations and simulation models suggest that these populations are relatively stable on a decadal time scale. The frequency and magnitude of recruitment pulses and high rate of adult survival provide considerable inertia, enabling persistence of these populations in the face of sporadic climatic extremes.

scholarly journals Does Larval Rearing Diet Lead to Premating Isolation in Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae)?

Insects ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 203
Author(s):  
Xue-Yuan Di ◽  
Bin Yan ◽  
Cheng-Xu Wu ◽  
Xiao-Fei Yu ◽  
Jian-Feng Liu ◽  
...  
Keyword(s):  
Mate Choice ◽  
Spodoptera Litura ◽  
Artificial Diet ◽  
Survival Rates ◽  
Intrinsic Rate Of Increase ◽  
Larval Rearing ◽  
Population Parameters ◽  
Premating Isolation ◽  
Behavioral Isolation ◽  
Rate Of Increase

Host plant preference during the larval stage may help shape not only phenotypic plasticity but also behavioral isolation. We assessed the effects of diet on population parameters and mate choice in Spodoptera litura. We raised larvae fed on tobacco, Chinese cabbage, or an artificial diet, and we observed the shortest developmental time and highest fecundity in individuals fed the artificial diet. However, survival rates were higher for larvae on either of the natural diets. Population parameters including intrinsic rate of increase and finite rate of increase were significantly higher with the artificial diet, but this diet led to a lower mean generation time. Copulation duration, copulation time, and number of eggs reared significantly differed between diets. In terms of mate choice, females on the artificial diet rarely mated with males fed on a natural host. Our results support the hypothesis that different diets may promote behavioral isolation, affecting mating outcomes. Thus, findings for populations fed an artificial diet may not reflect findings for populations in the field.

A Potential Systematic Error in Using Lysivane as Inhibitor in the Measurement of Amniotic Fluid Acetylcholinesterase by the Ellman Method

1983 ◽  
Vol 20 (3) ◽  
pp. 159-162 ◽  
Author(s):  
B A Webb ◽  
S J Richardson ◽  
R Garry ◽  
J Atkins
Keyword(s):  
Enzymatic Hydrolysis ◽  
Amniotic Fluid ◽  
Systematic Error ◽  
Neural Tube ◽  
Neural Tube Defects ◽  
Acidic Solution ◽  
Rate Of Increase ◽  
Background Absorption ◽  
Low Levels ◽  
Hydrolysis Of

The measurement of low levels of cholinesterase or acetylcholinesterase by the Ellman method requires correction for a non-enzymatic increase in absorption at 412 mμ that is due both to non-enzymatic hydrolysis of the acetylthiocholine substrate and to modification of the colour reagent. The rate of increase in absorption is dependent on temperature and pH. Addition of an acidic solution of lysivane to the assay solution for selective measurement of amniotic fluid acetylcholinesterase gives rise to a shift in pH; the use of methanol is suggested as an easier method of dissolving the inhibitor and does not affect the pH of the assay, obviating any need to redetermine the background absorption. There is, however, no improvement in ability of the method to predict pregnancies associated with neural-tube defects.

scholarly journals Population dynamics and net primary production of the aquatic macrophite Nymphaea rudgeana C. F. Mey in a lotic environment of the Itanhaém River basin (SP, Brazil)

2000 ◽  
Vol 60 (1) ◽  
pp. 83-92 ◽  
Author(s):  
A. F. M. CAMARGO ◽  
E. R. FLORENTINO
Keyword(s):  
Population Dynamics ◽  
Primary Production ◽  
Aquatic Macrophytes ◽  
Aquatic Macrophyte ◽  
Net Primary Production ◽  
Growth Period ◽  
Pistia Stratiotes ◽  
Annual Productivity ◽  
Lotic Environment ◽  
Low Levels

In this paper we evaluated the population dynamics and obtained estimates of the net primary production of the aquatic macrophyte Nymphaea rudgeana in an arm of the Itanhaém River (São Paulo State, Brazil). This species presents, in the studied area, a broad seasonal variation of biomass. As from November (13.1 g DW/m²) we observed a gradual increase of biomass that reached a maximum in February (163.1 g DW/m²). Then, the biomass decreased, maintaining low levels until a new growth period. The reduction of biomass is associated to the development of floating aquatic macrophytes (Pistia stratiotes and Salvinia molesta) and, subsequently to environmental factors (higher salinity values) that are unfavorable to their development. The net primary production of N. rudgeana was estimated from the biomass data, and the annual productivity value was estimated between 3.02 and 3.82 t/ha/year.

LIFE HISTORY PARAMETERS IN MELANOPLUS SANGUINIPES (F.) IN TWO CRESTED WHEATGRASS PASTURES

1988 ◽  
Vol 120 (1) ◽  
pp. 39-44 ◽  
Author(s):  
Norma E. Sanchez ◽  
Jerome A. Onsager
Keyword(s):  
Life History ◽  
Survival Rates ◽  
Adult Longevity ◽  
Melanoplus Sanguinipes ◽  
Crested Wheatgrass ◽  
Life History Parameters ◽  
Preoviposition Period ◽  
Point Estimates ◽  
Two Populations ◽  
Net Replacement

AbstractA combination of published techniques provided point estimates of life history parameters for two natural field populations of Melanoplus sanguinipes (F.) in crested wheatgrass pastures. Stage-specific survival rates averaged 0.4798, 0.2261, 0.7628, and 0.6903 for egg, instars I–III combined, instar IV, and instar V, respectively. Daily survival rates of adults averaged 0.9702, but were slightly lower for females than for males. Estimated duration of nymphal instars averaged 8.4 days, the adult preoviposition period averaged 13.3 days, and adult longevity averaged 26.7 and 36.3 days in the two populations. Oviposition rates were estimated for up to four successive ovipositions, and net replacement rates of populations also were estimated. Neither population replaced itself, indicating that potential capacities for increase were not approached under conditions of these studies.

scholarly journals Genetic diversity in different populations of sloths assessed by DNA fingerprinting

2002 ◽  
Vol 62 (3) ◽  
pp. 503-508 ◽  
Author(s):  
N. MORAES ◽  
J. S. MORGANTE ◽  
C. Y. MIYAKI
Keyword(s):  
Genetic Diversity ◽  
Genetic Variability ◽  
Dna Fingerprinting ◽  
Genetic Similarity ◽  
Similarity Indices ◽  
Different Populations ◽  
Related Individuals ◽  
Low Levels ◽  
Dna Profiles ◽  
Two Populations

In this study we analyzed a population of Bradypus torquatus with individuals originally distributed in different localities of Bahia, and two populations of B. variegatus with individuals from Bahia and São Paulo States. Using the DNA fingerprinting method, we assessed the genetic variability within and between populations. Analysis of the DNA profiles revealed genetic similarity indices ranging from 0.34 ± 0.07 to 0.87 ± 0.04. Similar low levels of genetic variability were found only in isolated mammalian populations or among related individuals. This study presents the first analyses of genetic diversity in sloth populations.

scholarly journals Low levels of inbreeding depression and enhanced fitness in cleistogamous progeny in the annual plant Triodanis perfoliata

Botany ◽  
2019 ◽  
Vol 97 (7) ◽  
pp. 405-415 ◽  
Author(s):  
Beth H. Ansaldi ◽  
Jennifer J. Weber ◽  
Carol Goodwillie ◽  
Steven J. Franks
Keyword(s):  
Inbreeding Depression ◽  
Mixed Mating ◽  
Life Stages ◽  
Annual Plant ◽  
Flower Type ◽  
Low Levels ◽  
Two Populations ◽  
Selfing Species

The maintenance of outcrossing in cleistogamous plants that produce both open, facultatively outcrossing chasmogamous (CH), and closed, obligate selfing cleistogamous (CL) flowers is puzzling because CL reproduction is thought to be more reliable and less costly. A possible explanation for the maintenance of CH flowers is the avoidance of inbreeding depression. However, inbreeding depression for cleistogamous species has rarely been quantified. In this study, we estimate levels of inbreeding depression in plants from three populations of Triodanis perfoliata (L.) Nieuwl., a dimorphic cleistogamous annual, under greenhouse conditions. Estimates of inbreeding depression at multiple life stages in all three populations were low and often not different from zero. Inbreeding depression at specific life stages varied, with two populations showing later-acting inbreeding depression, which is also found in other selfing species. In two of the study populations, selfed CL progeny outperformed selfed CH progeny, indicating a flower-type effect. The low levels of inbreeding depression and the superior fitness of CL compared with selfed CH flowers that we observed make the maintenance of CH flowers in this system surprising, and suggest that other advantages of outcrossing CH flowers are likely responsible for maintaining mixed mating in this species.

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