Population Ecology Research Research Articles

Structure and Dynamics of Spotted Salamander (Ambystoma maculatum) Populations in Missouri

Abstract: Comparisons of spatial and temporal variation in demographic rates are crucial to understanding population dynamics. Yet, even well-studied species are often lacking in comparisons of such variability in demographic data, making these contrasts imperative to conduct in population ecology research. We conducted a long-term monitoring study of Spotted Salamanders (Ambystoma maculatum) at five ponds in Missouri, USA. We sampled populations using drift fences, and monitored breeding immigration dates, adult population sizes, sex ratio, juvenile recruitment, metamorph sizes, and metamorph emigration dates. Generally, we found that our study populations exhibited characteristics similar to other populations across their distribution. We also found spatial and temporal variation among populations in nearly all demographic parameters, however, indicating that multipopulation and multiyear studies will likely improve our inferential abilities in understanding population dynamics. We observed an overall ...

Wild Turkey Movements During Flooding After Opening of the Morganza Spillway, Louisiana

Abstract The opening of the Morganza Spillway in Louisiana on 18 May 2011 to relieve historic flooding along the lower Mississippi river subsequently inundated thousands of acres of bottomland forest in the Atchafalaya basin. Since 2001, we have conducted Meleagris gallopavo silvestris (Eastern Wild Turkey) population ecology research on the Sherburne Wildlife Management Area, located approximately 30 km south of the Morganza spillway. In expectation of the Morganza spillway opening, between 11 and 14 May, we captured and fitted 5 (1 M, 4 F) adult Eastern Wild Turkeys with µGPS transmitters to monitor turkey response to basin flooding. By 19 May 2011, our study area was inundated with >3 m of flood waters, and remained completely inundated until 11 June 2011. Via radio-telemetry, we confirmed one female was depredated immediately before flood waters inundated our study site, and one female survived and reached dry ground created by receding water on 16 June. A second female lived 21 days and made circuito...

Path Dependence and Path Creation: Alternative Theoretical and Methodological Perspectives on Strategy, Innovation and Entrepreneurship

Path Dependence and Path Creation: Alternative Theoretical and Methodological Perspectives on Strategy, Innovation and Entrepreneurship

Tag loss probabilities are not independent: Assessing and quantifying the assumption of independent tag transition probabilities from direct observations

The ability to identify animals individually throughout their lives is a cornerstone of sound population ecology research. However, because not all marks are permanent it is important to accurately account for the loss of marks. To this end, animals are often marked with two marks to limit the chance of the animal being presumed dead i.e. lost to the study by being individually unidentifiable, when actually alive. To account for the eventuality that both marks are lost, mark loss rates are generally assumed to be independent and adjustments to the number of animals alive are made accordingly. This assumption that tags on the same animal are lost independently was tested within the multi-model-inference framework in a study of 5928 branded, tagged and weighed (at weaning) elephant seals at Macquarie Island. Our key finding was that the probability of loosing a second tag after the first had been lost was dependent on the probability of having already lost a first tag and that on average there was a 28.1% greater likelihood of loosing a second tag once the first had been lost. Indeed, there was no support (ΔQAIC c > 64.5) for models which included this assumption of independence. We found little evidence for differences in the tag loss rates between the sexes (ER = 1.08, i.e. models with and without the gender/sex variable were equivalent). However, we did find that heavier seals were more likely to retain their tags ( ψ 2:2 and ψ 1:1 combined) than lighter seals (0.96 year − 1 and 0.83 year − 1 respectively), and that lighter seals were more likely to move into the zero tag state than heavier seals ( ψ 2:0 0.386 year − 1 and 0.187 year − 1 respectively and ψ 1:0 0.121 year − 1 and 0.057 year − 1 respectively). We suggest that tag loss in lighter seals may exhibit a higher degree of dependence than heavier seals. Using age and site specific tag loss estimates are crucial when correcting survival estimates in mark–-recapture studies because there are a number of factors that may be responsible for differences in the rates of loss e.g. tag placement and animal condition. Importantly, there is a growing body of evidence, to which this study contributes, showing that the general assumption of independence to calculate double tag loss is flawed, we suggest that where possible permanent methods of marking should be considered ahead of other non-permanent methods.

Community‐level density dependence: an example from a shallow coral assemblage

While density dependence is a popular topic of research in population ecology, it has received much less attention at the community level. Using 27 years of data from Heron Island, on Australia's Great Barrier Reef, we develop a matrix model of coral community dynamics that shows that community-level density dependence does occur and that it is fairly common, being found in 38% of the model parameters for which it was tested. In particular, colonization of free space (through either recruitment or growth of existing colonies) was nearly always density dependent. There were no consistent patterns in the results for mortality, persistence, or species interactions. Most transitions were found to be dependent on the cover of the incoming species group, with only a few dependent on that of the outgoing species group. In addition, few of the transitions representing species interactions were dependent on the amount of free space present, suggesting that the cover of other species does not influence encounters. When these results were combined into a model of community dynamics, it was found that density dependence resulted in a moderate increase in coral cover, which was spread over most species groups. The dynamics of the density-dependent assemblage were also a lot noisier than those of an assemblage without density dependence. Sensitivity analysis indicated that it was density dependence in the colonization probabilities, particularly of encrusting acroporids, bushy Acropora and staghorn Acropora, which had the main influence on the model, although persistence of free space was also important. Transitions representing mortality were only of minor importance, and those representing species interactions were of no importance.

HABITAT FRAGMENTATION LOWERS SURVIVAL OF A TROPICAL FOREST BIRD

Population ecology research has long been focused on linking environmental features with the viability of populations. The majority of this work has largely been carried out in temperate systems and, until recently, has examined the effects of habitat fragmentation on survival. In contrast, we looked at the effect of forest fragmentation on apparent survival of individuals of the White-ruffed Manakin (Corapipo altera) in southern Costa Rica. Survival and recapture rates were estimated using mark-recapture analyses, based on capture histories from 1993 to 2006. We sampled four forest patches ranging in size from 0.9 to 25 ha, and four sites in the larger 227-ha Las Cruces Biological Station Forest Reserve (LCBSFR). We found a significant difference in annual adult apparent survival rates for individuals marked and recaptured in forest fragments vs. individuals marked and recaptured in the larger LCBSFR. Contrary to our expectation, survival and recapture probabilities did not differ between male and female manakins. Also, there was no support for the existence of annual variation in survival within each study site. Our results suggest that forest fragmentation is likely having an effect on population dynamics for the White-ruffed Manakin in this landscape. Therefore, populations that appear to be persisting in fragmented landscapes might still be at risk of local extinction, and conservation action for tropical birds should be aimed at identifying and reducing sources of adult mortality. Future studies in fragmentation effects on reproductive success and survival, across broad geographical scales, will be needed before it is possible to achieve a clear understanding of the effects of habitat fragmentation on populations for both tropical and temperate regions.

Heterogeneity studies of Carchesium polypinum (Ciliophora: Peritrichida) in Donghu Lake

In this article, RAPD was employed to detect the DNA polymorphism of Carchesium polypinum in three lakes: Nanhu Lake (N), Shahu Lake (S) and Donghu Lake (D). The results were used to deduce the definition of the populations: (1) The 20 primers produced 172 clear bands with an average of 8.6 fragments ranging from 100bp to 1600bp. The other 11 primers produced 59 legible bands with an average of 5.4 fragments ranging from 100bp to 1 500bp; (2) SPSS 12.0 and RAPDistance 1.04 that had similar trees were composed of two parallel main branches. Samples from Shijizhong (Z) of D, Shuiguohu (H) of D and N clustered into a branch and another sample from D — Fengguangcun (F) — gathered with S or made another main branch itself. The result that the three samples from D were separated by the samples from other lakes suggested that the individuals of C. polypinum in D belong to several populations. This discovery will promote micro-hydrobiont population ecology research. In addition, it will help in the study of the essence of the transitional zone and its dispersal and vicariance behavior. We believe that this study will contribute to the study of population differentiation and the mechanism of speciation.

Spatial Synchrony Among and Within World-Systems: Insights From Theoretical Ecology

This paper reports on research in population ecology and suggests ways it might be useful in explaining spatial dynamics of states, groups, and world-systems. In particular it focuses on how and why populations at opposite of ends of Afroeurasia come to rise and fall simultaneously over long periods of time. We call for exploration of research in population ecology for understanding world-system evolution and suggest directions for possible future research.

Life in a Niche: Mortality Anxiety Among Organized Interests in the American States

We extend recent research using a population ecology framework to understand the structure of interest communities by examining how niche resources and population density influence the survival prospects of inter ests organization. We indirectly assess how resources and density bear on survival by examining mortality anxiety-assessments of the likelihood that interest organization will soon face an existence-threatening crisis. Several hypotheses on mortality anxiety are extracted from the population ecology research program and tested with survey data on interest communities in six states.

Comparative Study of German Cockroach (Dictyoptera: Blattellidae) Population Sampling Techniques1

Eight German cockroach (Dictyoptera: Blattellidae) population sampling techniques were compared in laboratory and field studies. Abilities to generate sample numbers and accurately estimate important population qualities (e.g., nymph/adult and adult sex ratios) were determined. These results will benefit blatticide efficacy and cockroach population ecology research efforts. The trap developed by researchers at the University of California, Riverside, gave the most accurate qualitative information overall, while sampling the smallest portion of the population. Use of all other sampling techniques studied engenders risk of biases in sampling various population age and sex classes.