Low Population Growth Rates Research Articles

Disturbance-induced emigration: an overlooked mechanism that reduces metapopulation extinction risk.

Emigration propensity (i.e., the tendency to leave undisturbed patches) is a key life-history trait of organisms in metapopulations with local extinctions and colonizations. Metapopulation models of dispersal evolution typically assume that patch disturbance kills all individuals within the patch, thus causing local extinction. However, individuals may instead be able to leave a patch when it is disturbed, either by fleeing before being killed or simply because the disturbance destroys the patch without causing mortality. This scenario may pertain to a wide range of organisms from horizontally transmitted symbionts, to aquatic insects inhabiting temporary ponds, to vertebrates living in fragmented forests. We generalized a Levins-type metapopulation model of dispersal evolution by adding a new parameter of disturbance escape probability, which incorporates a second source of dispersal into the model: disturbance-induced emigration. We show that disturbance escape expands the domain of metapopulation viability and selects for lower rates of emigration propensity when disturbance rates are high. The fitness gains from disturbance-induced emigration are generally moderate, suggesting that disturbance escape might act more as a complementary dispersal strategy rather than a replacement to emigration propensity, at least for metapopulations that meet the assumptions of the Levins-type model. Yet disturbance-induced emigration may in some circumstances rescue a metapopulation from long-term extinction when the combination of high disturbance rates and low local population growth rates compromises its viability. Further, a metapopulation could persist exclusively by disturbance escape if local carrying capacities are large enough to counterbalance two sources of mortality: mortality driven by disturbance and mortality during dispersal. This study opens two promising research lines: (1) the investigation of disturbance escape in metapopulations of ephemeral habitats with unsaturated populations and non-equilibrium dynamics and (2) the incorporation of information costs to investigate the joint evolution of disturbance escape and emigration propensity.

Big Data Supported the Identification of Urban Land Efficiency in Eurasia by Indicator SDG 11.3.1

Indicator 11.3.1 of the UN Sustainable Development Goals (SDG 11.3.1) was designed to test land-use efficiency, which was defined as the ratio of the land consumption rate (LCR) to the population growth rate (PGR), namely, LCRPGR. This study calculates the PGRs, LCRs, and LCRPGRs for 333 cities from 1990–2000 and 391 cities from 2000–2015 in four geographical divisions in Eurasia according to the method given by UN metadata. The results indicate that Europe and Japan have the lowest PGR and LCR, indicating that this region’s level of urbanization is the highest. South and Central Asia have the lowest values of LCRPGR, indicating relatively lower urban land supply during the measurement periods. Compared with the mean LCRPGR in a region, the average values from SDG 11.3.1 by different types of cities in a region can have more guiding significance for urban sustainable development. While paying attention to the urban land-use efficiency of mega and extra-large cities, more attention should be paid to the coordination relationship between urban land supply and population growth in large, medium, and small cities. Additionally, the method from UN metadata works well for most urban expansion cities but is not suitable for cities with small changes in urban populations.

Responses of a pelagic fish community to reduced fishing pressure in the central Bering Sea

Ecosystem-based fishery management (EBFM) requires minimizing the risk of irreversible change to a natural assemblage of species. Because pelagic fisheries modify the biotic community rather than the physical environment and often target migratory species, the pelagic community can be expected to respond quickly after fishing pressure is reduced. We monitored the pelagic zooplanktivore community over 4 decades in the central Bering Sea before and after the closures of large-scale pelagic fisheries. We found a quick and steep change in the pelagic fish community structure after fishing pressure was reduced, which reflected increased abundance of salmon species; however, walleye pollock stocks, one of the most valuable fisheries resources in this area, have not recovered. A lower population growth rate might contribute to the slow recovery of pollock stocks. Long-term ecosystem monitoring of fishing grounds and surrounding ecosystems will be required for successful implementation of EBFM of pelagic fish stocks.

Decreasing Fertility, Economic Growth and the Intergenerational Wage Gap

Persistent low fertility rates lead to lower population growth rates and eventually also to decreasing population sizes in most industrialized countries. There are fears that this demographic development is associated with declines in per capita GDP and possibly also increasing inequality of the wage distribution. We investigate whether this is true in the context of neoclassical growth models, augmented with endogenous fertility decisions and endogenous educational decisions. Furthermore we allow for imperfect substitutability across workers of different age in the production process and learning by doing effects as well as human capital depreciation. In particular, we assess the intergenerational wage redistribution effects which follow after a demographic change to persistent low fertility rates.

Species distribution model reveals only highly fragmented suitable patches remaining for giant armadillo in the Brazilian Cerrado

The potential distribution of a cryptic, naturally rare large mammal, the giant armadillo Priodontes maximus, was explored in fragments of Cerrado and Atlantic Forest in the state of Mato Grosso do Sul (259,641 km2) Brazil. Watersheds (N = 344) throughout the state were surveyed for evidence of the species with 164 confirmed presences and 180 absences. A total of 144 independent presence points were used to model the current potential distribution of the species using the Maxent algorithm with 30 possible explanatory variables. Suitable and unsuitable areas, average patch size of suitable habitats and conversion rate of habitat from 1985 to 2018 were also calculated. Results highlight the severe fragmentation level of the suitable areas left for the giant armadillos, with suitable habitat patches (forest and savanna) surrounded by an agricultural matrix. Furthermore, only four suitable patches are larger than 100 km2 (132.63 ± 32.04 km2). Due to the species low population growth rate it is possible that individuals recorded are part of declining or functionally extinct populations. Further studies on the density and population trends of giant armadillos within this fragmented landscape will be key to understanding the potential long-term persistence of giant armadillos in the degraded Cerrado of MS.

Tasas de crecimiento somático de tortuga carey, Eretmochelys imbricata, en el Parque Nacional Natural Gorgona, Colombia, entre 2004 y 2018

La tortuga carey, Eretmochelys imbricata, se encuentra a nivel global en peligro crítico de extinción, y la información demográfica en el Océano Pacífico Oriental es limitada. Por esta razón, esta investigación evalúa las tasas de crecimiento somático en una agregación de individuos inmaduros de tortuga carey empleando el método de captura-marca-recaptura en los arrecifes coralinos de Playa Blanca y la Azufrada en el Parque Nacional Natural Gorgona, Colombia. Entre 2004 y 2018 se realizaron 89 capturas de 49 individuos de tortuga carey. El largo curvo del caparazón promedio (LCC) obtenido fue de 41,6 cm (rango 32-58 cm) y el largo recto del caparazón promedio (LRC) fue de 39,1 cm (rango 30,0-54,1 cm), lo que muestra que estos arrecifes son áreas de forrajeo importantes para individuos inmaduros de esta especie. El índice de condición corporal promedio fue de 1,3 (rango 1,0-1,5). Esto sugiere que las condiciones ambientales mantienen en buen estado la salud de esta agregación. Usando el modelo de crecimiento de von Bertalanffy y estableciendo una talla máxima (L∞) de 63 cm de LCC (donde se obtiene el menor coeficiente de variación), se estimó una k de 0,081 y una tasa anual de crecimiento promedio de 1,5 ± 1,8 cm/año. Esto indica que los individuos en esta agregación estarían alcanzando una LCC de 63 cm entre los 33 y 34 años, talla cercana a la de madurez sexual en la región del Pacífico oriental (aproximadamente 66 cm LCC). Lo anterior ratifica la vulnerabilidad de esta especie debido a las lentas tasas de crecimiento somático y madurez sexual tardía. Se sugiere que los esfuerzos de conservación para esta especie deben ser a largo plazo para procurar su recuperación, en vista de que especies con estas características tienden a expresar tasas de crecimiento poblacional muy bajas.

Archaeology, demography and life history theory together can help us explain past and present population patterns.

Population matters. Demographic patterns are both a cause and a consequence of human behaviour in other important domains, such as subsistence, cooperation, politics and culture. Demographers interested in contemporary and recent historical populations have rich data at their fingertips; the importance of demography means many interested parties have gathered demographic data, much of which is now readily available for all to explore. Those interested in the demography of the distant past are not so fortunate, given the lack of written records. Nevertheless, the emergence in recent years of a new interest in the demography of ancient populations has seen the development of a range of new methods for piecing together archaeological, skeletal and DNA evidence to reconstruct past population patterns. These efforts have found evidence in support of the view that the relatively low long-term population growth rates of prehistoric human populations, albeit ultimately conditioned by carrying capacities, may have been owing to 'boom-bust' cycles at the regional level; rapid population growth, followed by population decline. In fact, this archaeological research may have come to the same conclusion as some contemporary demographers: that demography can be remarkably hard to predict, at least in the short term. It also fits with evidence from biology that primates, and particularly humans, may be adapted to environmental variability, leading to associated demographic stochasticity. This evidence of the fluctuating nature of human demographic patterns may be of considerable significance in understanding our species' evolution, and of understanding what our species future demographic trajectories might be. This article is part of the theme issue 'Cross-disciplinary approaches to prehistoric demography'.

Simulated Indigenous fire stewardship increases the population growth rate of an understorey herb

Abstract Understanding how plant populations respond to multiple drivers is increasingly critical for biodiversity conservation under global change. Indigenous knowledge can provide guidance for sustainable management, but the outcome of its application in novel ecosystems is rarely known. Simulating the re‐introduction of Indigenous stewardship in contemporary contexts with population models allows for the comparison of different management scenarios and the elucidation of the mechanisms driving population outcomes. Beargrass Xerophyllum tenax is an ecologically and culturally important understorey plant managed through fire and leaf harvest by Native Americans. We collected demographic and abiotic data on beargrass over 3 years across fire severities in nine populations and conducted an experiment to simulate Native American leaf gathering. These data were used to build integral projections models (IPMs) with soil moisture and light availability as covariates. With these IPMs, we simulated stochastic population growth rates across future fire and leaf harvest scenarios. We then decomposed our simulation results using stochastic life table response experiments (SLTREs). The ‘no fire’ and ‘business as usual’ (180‐year fire return interval, 58% probability of high‐severity fire) scenarios resulted in lower population growth rates than ‘Indigenous fire stewardship’ (10‐year fire return interval, 10% chance of high‐severity fire). SLTREs revealed that Indigenous stewardship led to higher beargrass population growth rates due to greater fire frequency, higher adult survival and increased vegetative reproduction. Fire also interacted with harvest in the simulations; leaf harvest increased population growth rate only in combination with Indigenous fire stewardship. Synthesis. Stochastic and retrospective population dynamics tools combined with an understanding of Indigenous management practices allow for the comparison of future socio‐ecological scenarios as well as mechanistic understanding of differences between scenarios. Simulated Indigenous stewardship supported the long‐term persistence of X. tenax populations while business as usual and no fire did not. The benefits of Indigenous stewardship to population dynamics, and the complexity of interactive effects of multiple drivers, provide further impetus for collaboration across Indigenous and western knowledge systems. Xerophyllum tenax is presented as a model system to explore the influence of Indigenous stewardship, or its absence, on population dynamics.

Finding clarity in ecological outcomes using empirical integrated social–ecological systems: A case study of agriculture‐dependent grassland birds

Abstract Efforts to monitor and conserve populations and ecosystems in human‐dominated landscapes can benefit from an empirical social–ecological systems approach. Here we illustrate how latent variable structural equation modelling of regional time series data can effectively describe interconnected drivers of population fluctuations in dynamic landscapes and can help to reveal previously unknown system drivers. Using a declining farmland‐dependent bird species (Ammodramus savannarum) in the eastern United States (1994–2015) as a case study, our analysis reveals how farm management decisions drive population fluctuations (R2 = 20%), while management is in turn highly influenced by climate (R2 = 23%–51%), but not by regional conservation spending. Synthesis and applications. Structural equation modelling revealed potential social–ecological pathways for halting regional population declines in a grassland bird, the Grasshopper Sparrow. Lower population growth rates followed years of higher hay yields (~4 percentage points per metric ton increase in hay yield) and later harvests (~2 percentage points per 10‐day delay in harvest). Thus, one pathway for stabilising regional populations could involve compensating farmers for reducing hay harvests, potentially requiring a six‐fold increase in current annual agri‐environmental conservation spending.

Breeding transients in capture\u2013recapture modeling and their consequences for local population dynamics

Standard procedures for capture–mark–recapture modelling (CMR) for the study of animal demography include running goodness-of-fit tests on a general starting model. A frequent reason for poor model fit is heterogeneity in local survival among individuals captured for the first time and those already captured or seen on previous occasions. This deviation is technically termed a transience effect. In specific cases, simple, uni-state CMR modeling showing transients may allow researchers to assess the role of these transients on population dynamics. Transient individuals nearly always have a lower local survival probability, which may appear for a number of reasons. In most cases, transients arise due to permanent dispersal, higher mortality, or a combination of both. In the case of higher mortality, transients may be symptomatic of a cost of first reproduction. A few studies working at large spatial scales actually show that transients more often correspond to survival costs of first reproduction rather than to permanent dispersal, bolstering the interpretation of transience as a measure of costs of reproduction, since initial detections are often associated with first breeding attempts. Regardless of their cause, the loss of transients from a local population should lower population growth rate. We review almost 1000 papers using CMR modeling and find that almost 40% of studies fitting the searching criteria (N = 115) detected transients. Nevertheless, few researchers have considered the ecological or evolutionary meaning of the transient phenomenon. Only three studies from the reviewed papers considered transients to be a cost of first reproduction. We also analyze a long-term individual monitoring dataset (1988–2012) on a long-lived bird to quantify transients, and we use a life table response experiment (LTRE) to measure the consequences of transients at a population level. As expected, population growth rate decreased when the environment became harsher while the proportion of transients increased. LTRE analysis showed that population growth can be substantially affected by changes in traits that are variable under environmental stochasticity and deterministic perturbations, such as recruitment, fecundity of experienced individuals, and transient probabilities. This occurred even though sensitivities and elasticities of these parameters were much lower than those for adult survival. The proportion of transients also increased with the strength of density-dependence. These results have implications for ecological and evolutionary studies and may stimulate other researchers to explore the ecological processes behind the occurrence of transients in capture–recapture studies. In population models, the inclusion of a specific state for transients may help to make more reliable predictions for endangered and harvested species.

Can multi‐species shark longline fisheries be managed sustainably using size limits? Theoretically, yes. Realistically, no

Abstract Size limits are a common fisheries management strategy that are applied to many fisheries and species. Most size limits use a minimum legal size to protect adult fish as per the ‘reproduce at least once’ paradigm, where stock collapse becomes impossible if every adult can produce one spawner prior to harvest. These approaches can be useful in fisheries where determining catch is difficult and therefore catch limits can be ineffective and potentially cause stock decline. Shark longline fisheries can be complicated to manage due to a deficiency of species‐level reporting. Catch limits are therefore difficult to determine, creating a need for other management measures. Here, three different size‐based management approaches were tested using the shark longline fishery from Papua New Guinea as a case study. These approaches included minimum size, maximum size and harvest slot approaches. Age‐structured Leslie matrix models revealed a broad range of productivities for 12 commonly caught species, ranging from low population growth rates of 1% per year for pelagic thresher sharks Alopias pelagicus to >33% per year for blue sharks Prionace glauca. Therefore, different harvest strategies were required for each species to be fished sustainably. However, management could be applied by grouping similar and easily distinguishable groups of species together. Synthesis and applications. The most pragmatic harvest strategy for all shark species included in this study was to limit harvest to mature individuals using minimum legal sizes. This provided sufficient resilience for all species to tolerate higher levels of fishing mortality than the Papua New Guinea (PNG) longline fishery could impose. Legal minimum lengths were derived from the largest length‐at‐maturity within each species group. However, while this produced a sustainable harvest strategy, issues with selectivity, post‐release mortality, interactions with other fisheries, economic viability and illegal, underreported and unregulated fishing were challenges to restricting fishing to the correct size classes and overall management efficacy. Therefore, while theoretically viable harvest strategies were outlined, it is apparent that size limits would not ensure that these shark species are fished sustainably. Therefore, the PNG longline fishery cannot operate sustainably if it were to reopen using size limits as its sole management strategy.

The energetic basis of population growth in animal kingdom

Population growth, and other population characteristics, have been computed and made available online for over 2000 animal species in the Add-my-Pet (AmP) collection, assuming constant food and temperature environments. The AmP collection – online database of Dynamic Energy Budget model parameters, implied properties and referenced underlying data – provides an unique opportunity to study how energetics of individuals relates to population growth. For the comparisons of traits, we assume that the background hazard rate is zero, but aging applies to all species and ‘thinning’ to species with high reproduction rates. The new concept ‘thinning’ is a state-dependent hazard rate such that the feeding rate of a cohort does not change in time: the increase of individual feeding rates due to growth is exactly compensated by a reduction in numbers. Thinning affects population growth rate, but the impact differs substantially between species. Some 11% of species do not survive thinning, even at abundant food. The population growth rate relates to the underlying energetics; we discuss and suggest explanations for how population growth rates fit into all known patterns in the co-variation of parameter values: body size-scaling, metabolic acceleration, waste-to-hurry, supply-demand spectrum and altricial-precocial spectrum. We show that, after reproduction, age at puberty dominates population growth. The specific population growth rate scales with maximum body weight in the same way as the weight-specific respiration scales with body weight. DEB theory, which explains both, shows, however, that no direct relationship exists between the population growth rate and respiration. We suggest that the similarity in scaling results from the equality between specific population growth and specific growth rate at maximum growth of structure, and might be an evolutionary relict from times that life consisted of dividing unicellulars; population and body growth are directly connected for unicellulars. We show that the specific growth rate at maximum growth equals 1.5 times the von Bertalanffy growth rate, in a DEB context, which is a new interpretation of the latter growth rate. We expected the population growth rate to co-vary with specific somatic maintenance rate, based on a previously discovered pattern, called the waste-to-hurry strategy, where growth and reproduction are increased by simultaneously increasing assimilation and somatic maintenance in species that live off temporarily abundant food supplies. We did find this effect in ecdysozoa and spiralia, which comprise roughly 95% of animal species, but hardly so in tetrapods. The reason might be that specific somatic maintenance also co-varies with specific maturity levels at puberty for tetrapods. The scaled functional response at which the population growth rate is zero is very close to that at which puberty can just be reached in absence of thinning, and somewhat higher in presence of thinning. The specific population growth rate at abundant food correlates negatively with the functional response for which population growth rate is zero. It also correlates negatively with the precociality index, i.e. the ratio of maturity levels at puberty and birth: the more precocial, the larger neonate size, the smaller reproduction rate, especially in restricted taxa such as mammals and cartilaginous fish. Like other traits, the population growth rate shows considerable segregation among taxa, where mammals have a relatively low rate, glires a relatively high rate among mammals, followed by marsupials; afrotherians have the lowest population growth rates.

The comparative energetics of petrels and penguins

Petrels and penguins form the clade Austrodyptornithes. The Add-my-Pet collection of referenced data and Dynamic Energy Budget (DEB) parameters presently has 64 members of this clade. Adaptations to their wandering life style could now be studied; I here try to characterise this clade from an energy perspective. It turned out that petrels are in several respects extreme among birds, showing adaptations to life at low mean food levels. Penguins show the same tendency, but less extreme. Almost all petrel species show a weight-reduction well prior to fledging till the adult weight. This permanent weight reduction suggests that the mean adult feeding level is about 80% of the maximum one. This pattern is well-captured by the standard DEB model, in which (energy) reserve plays an important role. They also have relatively large eggs, and long incubation times and low reproduction rates. I argue that large eggs minimize the age at fledging, given that a particular maturity threshold needs to be reached for fledging. Austrodyptornithes have a high age at puberty, which, in combination with low reproduction rates, causes very low maximum population growth rates. The energy allocation to reproduction for petrels is typical among birds, so the low reproduction rates are the results of the large eggs. Another adaptation to low mean food levels is the large stomach/gut capacity, which appeared to be coupled to a high reserve capacity. This points to be an adaptation to a patchy occurrence of their food, probably in combination with spells of poor weather conditions for feeding. Petrels have a high supply stress and altriciality coefficient, compared to birds, while penguins are a very small altriciality coefficient. This reflects a very high maturity level at puberty for both taxa, in combination with high maturity level at birth for petrels and a typical one for penguins. They have a relatively long life span, compared to other birds, but not extreme. The relative egg size of penguins is typical for birds, to smaller than typical. Penguins combine small eggs with long foraging trips, while small young need frequent feeding. They evolved two adaptation for this: crop milk feeding and collecting lipid-rich food for their offspring. The energetic differences that have been found between petrels and penguins may directly relate to feeding in surface waters by petrels and in deeper waters by penguins; seasonal fluctuations in food density are more pronounced in surface waters. The higher clades Aequornithes and Aequorlitornithes are in many respect intermediate between Austrodyptornithes and other birds, demonstrating a clear taxonomic coherence in energy parameters.

Biology and life table analysis of Tetranychus urticae (Acari: Tetranychidae) on different common pea and bean cultivars

The quality of the important host plants affects the survival, development, and reproduction of the two-spotted spider mite, Tetranychus urticae Koch. The biology and life table parameters of T. urticae, on four cultivars of common Regular and Sweet pea and Polesta & G6 bean, were examined under laboratory conditions of 27 ± 1 ℃, 60–80% R.H. and photoperiod 16L: 8D h. Both males and females of T. urticae successfully developed from egg to adult on different host plants. Results revealed that the survival rate varied from 53% on Regular pea to 99% on G6 bean cultivars. The developmental time from egg to adult was significantly influenced among the tested host plant cultivars and ranged from 9.75 days on G6 bean to 20.42 days on Regular pea (p = 0.00). Female longevity was significantly longer on Regular and Sweet pea than on Polesta and G6 bean. The highest fecundity per female was recorded on G6 bean, but the lowest was on Regular pea cultivars. Consequently, population growth parameters were also significantly influenced by different host plants. The net reproductive rate (R0), the intrinsic rate of natural increase (r), and the finite rate of increase (λ) of T. urticae were significantly higher on G6 bean than the other three cultivars. Also, the longest mean generation time (T) and doubling time (DT) were noted on Regular pea, but the shortest value on G6 and Polesta bean cultivars. Obtained results based on the intrinsic rate of natural increase revealed that G6 and Polesta bean were more suitable than the two pea cultivars as hosts for T. urticae. Therefore, the lower population growth rate of the T. urticae could be the result of antibiotic resistance in the cultivars Regular and Sweet pea.

Bank’s marketing policy formation in a pandemic as ensuring resilience in the Russian economy

The gist of this article boils down to improving the efficiency of the bank’s marketing policy in a pandemic. The growing needs of buyers, the growth of non-price competition and the supply of goods and services on the market indicate the relevance of the problem of forming a marketing policy. Factors such as imperfection of market relations, inflation, low population growth rate, high level of income differentiation of the population are characteristic of the Russian market. The article stresses that it is necessary to conduct a marketing policy competently in order to ensure the return on capital and a stable position in the market. The main hypothesis is based on changing consumer preferences. The marketing research was conducted by a survey method in the form of a survey of respondents. The aim of the study was to determine the strengths and weaknesses of the organization providing credit products. A survey of consumers of credit products made it possible to determine vectors and control points when choosing a product by a consumer. This, in turn, made it possible to determine the parameters of the loan products, which need to be changed in order to increase the degree of customer satisfaction. The criteria for choosing a loan, the preferred channels for obtaining a loan and the attitude towards credit institutions that provide loans have also been determined. The article presents the activities that determine the marketing policy for future periods.

The impact of population aging in rich countries: What’s the future?

The paper examines the impact of population ageing on macroeconomic outcomes, inflation and labour force participation employing a sample of 23 OECD developed countries from 1960 to 2014 and accounting for the institutional context. Controlling for collective bargaining coordination the results show that a larger elderly share of population would lead to lower real GDP growth, albeit mostly in countries with low population growth rates. Ageing puts substantial downward pressure on inflation due to subdued aggregate demand. Also, results demonstrate that the ageing of the workforce tends to reduce labour supply. To mitigate any adverse effects of population ageing, a combination of labour market policies, pension reforms, greater investment in human capital and technological innovation should be prioritized in policy making.

Modeling Urban Growth and Land Cover Change in Albuquerque Using SLEUTH

This research examines the impact of urban development on three major development areas (Mesa del Sol, Volcano Mesa, and Santolina) in Albuquerque, New Mexico, based on the past pattern of urban growth and development that has occurred in the city. We investigate urban growth in these areas using (1) a business-as-usual scenario, where urbanization in these areas is based on historical urban growth and without any explicit definition of these development areas, and (2) an expansion scenario, where these development areas are explicitly defined as areas preferred for urbanization. Each scenario is further explored based on possible high and low population growth rates. We use SLEUTH, a dynamic urban growth model, for future urban growth prediction. Results from the model indicated that urban growth predominantly occurs as infill and at the fringes of the current urban extension. For the three development areas, a high probability of urban growth was seen in Volcano Mesa, followed by Mesa del Sol, and a low probability of urban growth was observed in Santolina. Furthermore, the results suggest that Volcano Mesa would have been developed regardless of it being designated as a development area, whereas urban growth in Santolina was particularly attributable to it being designated as a development area. Key Words: Albuquerque, land cover change, SLEUTH, urban growth, urbanization.

PENGARUH PERBEDAAN JENIS MEDIA ALAMI DAN EKOSISTEM TERHADAP KEANEKARAGAMAN DAN LAJU PERTUMBUHAN JENIS MOLUSKA DI PERAIRAN PESISIR SEKOTONG

Mollusca are one of the fouling (biofouling) organisms attaching to hard objects in the sea and freshwater waters. The attachment and growth of fouling organisms is a serious problem because it is one of the factors that can damage the structure of building materials and has a considerable impact on the development of the marine industry. This study aimed to determine the effect of distinction of natural media placed in three ecosystems towards species diversity and growth rates of mollusca. The observation of attachment conditions and growth of the mollusca populations in each media were documented by using an underwater camera. Based on the results of research and identification, the researcher found that there were 5 species from 2 classes namely Gastropoda and Bivalvia and 2 family named Vermetidae and Ostreidae. The attached species of Gastropoda class was only Petaloconchus varians, while species of Bivalvia class were Planostrea pestigris, Alectryonella plicatula, Ostrea edulis and Crassostrea gigas. The most abundant species were found in tile media with an abundance of 1,014 individuals / cm2. While the lowest abundance of individuals was found in stone media which was equal to 0.141 individuals/cm2. The species with the highest population growth rate was the species of Petaloconchus varians with a total population growth rate of 11.66 ind/ week. While species with the lowest population growth rate was found in Alectryonella plicatula species with a total population growth rate of 0.16 ind/ week.

Reversible colony formation and the associated costs in Scenedesmus obliquus

AbstractGrazer-induced colony formation as a defense strategy in microalgae such as Scenedesmus species has been widely reported, but the associated costs and reversibility of the colonies are rarely studied. We experimentally showed that Scenedesmus obliquus formed chained colonies in the presence of a predator, including predators separated from the algae by a membrane, but quickly reverted to single cells after the removal of the predator—a defining characteristic of an inducible defense. We detected stress indicators—astaxanthin esters—in the algal populations in the presence of grazers but not when grazers were absent. We found significant costs associated with S. obliquus colony formation in terms of lower population growth rate, lower photosystem II efficiency and lower cellular chlorophyll a content. These results together show that colony formation as an inducible defense in S. obliquus against grazers comes at a substantial cost such that the defense must be switched off and the colonies revert to single cells when the predation risk disappears.

Demographic senescence and effects on population dynamics of a perennial plant.

Demographic rates in plants are usually assumed to be more stage or size dependent than age dependent, and aging is therefore not considered in demographic models. However, little is known about the effect of age on demographic rates, as there still are few studies based on long-term individual-based plant population data that consider both individual age and size. In addition, little is known about how aging of individuals may affect population dynamics. We present analyses of demographic data for three populations of Fumana procumbens collected 1985-2013, on individuals with known year of germination. We modeled age- and size-dependence of the vital rates of survival, growth, fruiting probability, and fruit number using thin plate spline regressions, and constructed an age×size integral projection model (IPM) to project population-level effects of aging. We found strong correlations between age and vital rates in solely age-based vital rate models, where vital rates initially increased with age, after which they stabilized and, in some cases, eventually declined. In survival models with both age and size, the effects of age were statistically significant, whereas size effects were insignificant at two of the sites. For other vital rates, most of the effect of age could be explained by size alone. In addition, including the age effects on survival in the IPM led to lower population growth rates compared to predictions of a size-only IPM. These results illustrate that demographic senescence does occur in perennial plants, which has only been demonstrated clearly in a few recent detailed studies. Moreover, we show that population projections may be overly optimistic if they do not consider plant age. We conclude that the possibility of demographic senescence should be considered in demographic population models, such as those used in viability analyses of threatened species.