Rapid Increase In Population Size Research Articles

High-resolution hydrodynamics of coral reefs and tracing of pollutants from hotel areas along the west coast of Unguja Island, Zanzibar

A rapid increase in population size along with expansion in hotel investment have been identified as key drivers of marine pollution in Zanzibar coastal waters. A validated high-resolution hydrodynamic tracer model was used to estimate the dispersal and impact range of pollutants from the main hotel areas along the western coastline of Unguja Island. The model showed the highest impact of pollutants from land during the northeast monsoon season due to the weakening of the main current. Marine protected areas with short distances to hotel areas and weak tidal currents were more likely to be impacted by pollutants from land than the more remote areas with higher flushing in agreement with water quality and seagrass health measurements. Cumulative effects of pollutants instead of single sources are important to consider for integrated wastewater treatment plans and management strategies to reduce pollution for the protection of biodiversity and guide future monitoring.

Reproductive Potential of Stone Moroko (Pseudorasbora parva, Temminck et Schlegel, 1846) (Teleostei: Cypriniformes: Gobionidae) Inhabiting Central Europe.

Simple SummaryStone moroko (topmouth gudgeon, Pseudorasbora parva) is a small fish that originates from the East Asia. The fish is an invasive species that extends its global distribution. The study aimed to assess the reproductive potential of the stone moroko in a new habitat in central Europe based on an analysis of the sexual cycle. A rapid sexual maturation and high-fecundity spawning in portions prolonged the four-month reproductive period, which enables a rapid increase in population size and density on a newly inhabited area. Furthermore, the smaller investment in gonad development in males allows them to retain vitality for nest protection and a longer reproductive season compared to the autochthonous cyprinid fish. The present study suggests that stone moroko population in Central Europe may exhibit a higher reproductive potential than native populations.Similar to other invasive species, stone moroko is extending its global distribution. The present study aimed to assess the reproductive potential of stone moroko fish in a new habitat in Poland based on analysing the sexual cycle and fecundity. Fish morphometric data, age, and gonadal structures were analysed. Fish age ranged from 0+ to 5+ years. Most females and males (93% and 60%, respectively) had reached sexual maturity in the first year of their life, with the smallest length of 25 mm and 28 mm, respectively. The mean, standard length of the body was 50 mm. The spawning season was spread over four months from late-April to mid-August. Females laid eggs in portions, and the absolute and relative fecundity was 1372 and 1691, respectively. Stone moroko males were ready to spawn for a longer time period than females. The present study shows greater reproductive potential of stone moroko population in the central Europe than the native population, suggesting its successful colonisation in the new habitat.

Multi-decadal shifts in the distribution and timing of Pacific herring (Clupea pallasii) spawning in Prince William Sound, Alaska

The location and timing of spawning play a critical role in pelagic fish survival during early life stages and can affect subsequent recruitment. Spawning patterns of Pacific herring (Clupea pallasii) were examined in Prince William Sound (1973–2019) where the population has failed to recover since its collapse in 1993. Abrupt shifts in spawn distribution preceded the rapid increase in population size in the 1980s and later its collapse by one and two years, respectively. Following the population collapse, spawning contracted away from historical regions towards southeastern areas of the Sound, and the proportion of occupied spawning areas declined from 65% to <9%. Spatial differences in spawn timing variation were also apparent, as the median spawn date shifted earlier by 26 days in eastern and 15 days in western areas of Prince William Sound between 1980 and 2006, and then shifted later by 25 (eastern) and 19 (western) days over a 7-year period. Effects of contracted spawning areas and timing shifts on first-year survival and recruitment are uncertain and require future investigation.

The genetic history of Greenlandic-European contact

SUMMARYThe Inuit ancestors of the Greenlandic people arrived in Greenland close to 1,000 years ago.1 Since then, Europeans from many different countries have been present in Greenland. Consequently, the present-day Greenlandic population has ~25% of its genetic ancestry from Europe.2 In this study, we investigated to what extent different European countries have contributed to this genetic ancestry. We combined dense SNP chip data from 3,972 Greenlanders and 8,275 Europeans from 14 countries and inferred the ancestry contribution from each of these 14 countries using haplotype-based methods. Due to the rapid increase in population size in Greenland over the past ~100 years, we hypothesized that earlier European interactions, such as pre-colonial Dutch whalers and early German and Danish-Norwegian missionaries, as well as the later Danish colonists and post-colonial immigrants, all contributed European genetic ancestry. However, we found that the European ancestry is almost entirely Danish and that a substantial fraction is from admixture that took place within the last few generations.

In the Shadow of the Mountain: A Socio-Historical Case Study on Rapid Population Growth in Two Neighboring Population Centers in the Western United States

US Census population estimates show that every state in the Western US reported significant population growth increases over the past two decades. Furthermore, Western population growth represents one of the largest and most significant US demographic trends in recent decades. For many Western US communities, this increase in population growth has resulted in significant changes to its residents’ day-to-day lived experience. Dramatic population growth can change the types of services available, economic opportunities, and perceived satisfaction of communities. This change in the lived experience of a community is perhaps most pronounced when small rural communities undergo a rapid increase in population size. To that end, we present a socio-historical narrative case study examining how population growth-historical and contemporary-has shaped residents’ lived experience in two neighboring population centers in the modern rural West: Utah’s Heber Valley and Park City, Utah.

A temperature- and photoperiod-driven model reveals complex temporal population dynamics of the invasive box tree moth in Europe

The box tree moth, Cydalima perspectalis, is an invasive insect that has rapidly colonised Europe, damaging to natural and ornamental box trees. In its native habitat in China, the number of generations per year is variable, but the number of generations observed in European climates remained unclear. This is a key issue for understanding the rapid increase in population size and range, and for optimising control. We developed a temperature- and photoperiod-driven model to simulate the life cycle of this insect and development rates for each life stage. The model was calibrated on published data and validated with observations obtained in France and Switzerland. Model stability analysis showed that minimal temperature for larval development to be the most important parameter to estimate. Diapause parameters had little effect. We then explored the effects of temperature increases of 1 and 2 °C. The number of generations ranged from two to four at the various study sites. Climate warming will accelerate the insect life cycle, making it possible for the occurrence of one more generation per year. The key finding of this study was the complexity of population dynamics for this species. Some generations overlapped, making it difficult to identify the adult flight period clearly for each generation. Furthermore, various stages were potentially able to overwinter, not just diapausing larvae. Climate warming may also enhance this phenomenon in the future. Further explorations of the complex dynamics of this species are required, notably it remains unclear how successfully the various life stages survive winter temperatures. Further model refinements are also required to obtain more accurate estimates of box tree moth phenology. However, this is the first phenology model for box tree moth to be published, and our findings provide useful information for improving control of this pest.

Could the intrinsic rate of increase represent the fitness in terrestrial ectotherms?

The intrinsic rate of increase (rm) has been considered as an important indicator of fitness in terrestrial ectotherms since long. It is actually an equivalent to the instantaneous growth rate of the exponential equation for describing the density-independent population growth. In terrestrial ectotherms, rm has been demonstrated to be temperature-dependent. The temperature at which rm was maximal, was considered to be the “optimal” temperature for fitness in Amarasekare and Savage (2012), but this definition needs further analysis. Only rm cannot provide thorough representation of fitness. Because body size can affect the competitive abilities in many terrestrial ectotherms, both population size and body size should be considered in measuring the fitness of ectotherms. The rule of “bigger is better” requires relatively low temperature to increase in body size, whereas relatively high temperature is required for a rapid increase in population size. Thus, there is presumably a trade-off in temperature for adjusting individual body size and population size to achieve maximum fitness. We hypothesized that this temperature could be reflected by the intrinsic optimum temperature for developmental rate in the Sharpe–Schoolfield–Ikemoto model, and it led to a temperature estimate around 20°C. However, the traditional viewpoint based on the temperature corresponding to the maximal intrinsic rate of increase provides a temperature estimate around 30°C. This study suggests that a low temperature around 20°C might authentically represent the optimal ambient temperature for fitness in terrestrial ectotherms. It implies that thermal biologists who are interested in the effect of temperature on the fitness in terrestrial ectotherms should pay more attention to their performance at low temperature rather than high temperature.

Population Structure ofAegialitesBeetles (Coleoptera, Salpingidae) on the Coasts of Hokkaido, Northern Japan

We conducted a molecular phylogeographic analysis of Aegialites beetles sampled on the coasts of Hokkaido, northern Japan, using a partial sequence (553 bp) of the mitochondrial ND2 gene. The beetles are flightless and are adapted to the supralittoral zone of rocky shores. In all, 249 individuals from 17 populations were included in the molecular analysis. Haplotypes of the Aegialites beetles studied comprised two distinct lineages with different distributional ranges: one (lineage A) on the coasts of Hokkaido facing the Sea of Japan and the Sea of Okhotsk, and the other (lineage B) mostly on the Pacific coast and on the Shiretoko Peninsula in northeastern Hokkaido. These haplotype lineages clearly indicate two groups of populations, one comprising lineage A haplotypes (group A) and the other lineage B haplotypes (group B). Only one population, at Taisei facing the Sea of Japan on the Oshima Peninsula, contained a mixture of haplotypes from the two lineages. Genetic divergence among populations was larger in group B than in group A. Despite the unidimensional nature of the beetles' habitat, no correlation was found between the degree of genetic differentiation and geographic distance in either group of populations. Population genetic parameters suggested that the two lineages originated in the Pliocene, and that the populations in group A underwent a rapid increase in population size, whereas those in group B did not. We present a scenario for the allopatric divergence of the two lineages.

Extraordinarily low mortality rates reported in juvenile Pacific oysters in the German Wadden Sea

In a recent publication in Helgoland Marine Research, Schmidt et al. (2008) report the rapid spread of the Pacific oyster (Crassostrea gigas) into the East Frisian Wadden Sea. They conclude that the observed rapid increase in population size was facilitated by low-mortality rates in juveniles. Particularly for the period between *0.5 and *1.5 years after settlement, they report extremely low mortality when compared with the next year, when instantaneous mortality rates in the same area and in the same cohort were an order of magnitude higher (compare Table 1). Detailed observations on this oyster cohort in another part of the German Wadden Sea by Diederich (2006) revealed even higher mortality rates for the first half year after settlement, i.e. in the period preceding the one of the supposedly low mortality. Generally, mortality rates in bivalves decline from high values in fragile spat to much lower levels in robust adult stages. Several examples of such declining trends in age– mortality relationships in marine bivalves are available from the literature, e.g. Walne (1961) in Ostrea edulis, Brousseau (1978) in Mya arenaria, Nakaoka (1996) in Yoldia notabilis, and Van der Meer et al. (2001a, b) in Macoma balthica. A reverse pattern of a strongly increasing mortality rates from an age of *1 to an age of *2 years as reported by Schmidt et al. (2008) appears to be unusual and asks for a specific explanation. Consistent sampling errors in the assessment of numerical densities at the start and/or end of the period of observation are bound to bias estimates of mortality: underestimating initial numbers or overestimating final numbers would both cause an underestimation of mortality. Underestimates of initial numbers could arise from overlooking part of the individuals present. Particularly in the summer of 2003, when initial numbers were estimated, Schmidt et al. (2008) made an enormous effort by determining numbers of small oysters at 15 mussel beds that were each sampled at no less a number than 100 sites of 1 m each, resulting in records of many thousands of juvenile oysters. At the time of first sampling, the shell lengths of the oysters mostly amounted to around 40 and 20 mm, respectively, in the two frequently sampled mussel beds, but they ranged down to only 5–10 mm in both beds. Searching for these small oysters on the mussel clumps was entirely done in the field, as different from the procedure followed by Diederich (2006), who searched the spat with a stereomicroscope in the laboratory. Apparently, Schmidt et al. did not check their field counts in any way. Overestimates at the end of the observation period might arise from wrongly including individuals of a younger cohort. Allocation to a specific cohort was done using length–frequency distributions. At the time of sampling, the lengths of the individuals of the two cohorts concerned showed substantial overlap. Again, a check is not stated. Another source of errors might arise from changes in mussel distribution. As oysters were counted exclusively within mussel beds, any change in the size of these beds or in the numbers of mussels within these beds would also affect estimates of oyster numbers. Mussels might move away from beds or immigrate into beds and such moving mussels may or may not bear attached oysters. Although we are not aware of any quantitative studies of oyster Communicated by H.-D. Franke.

Population dynamics and rates of molecular evolution of a recently emerged paramyxovirus, avian metapneumovirus subtype C.

We report the existence of two distinct sublineages of avian metapneumovirus (MPV) subtype C, a virus which has caused serious economic loss in commercial turkey farms in the United States. This subtype is closely related to human MPV, infects multiple avian species, and is globally distributed. The evolutionary rates of this virus are estimated to be 1.3 x 10(-3) to 7 x 10(-3) substitutions per site per year, and coalescent estimates place its emergence between 1991 and 1996. The four genes examined show a concordant demographic pattern which is characterized by a rapid increase in population size followed by stable population grown until the present.

GENETIC CONSEQUENCES OF REINTRODUCTIONS: AN EXAMPLE FROM OREGON PRONGHORN ANTELOPE (ANTILOCAPRA AMERICANA)

Abstract In 1969, 17 pronghorn were reintroduced onto Umatilla Army Base in Oregon with no subsequent translocations or immigration into this fully enclosed area. We explored the genetic signature this event left on the population using a combination of microsatellite genotypes and mitochondrial DNA (mtDNA) sequencing data of this population. We compared the present day Umatilla herd to its source population and to a southeastern Oregon population. We found the reintroduced population had sharply lower genetic diversity compared to its source despite its rapid increase in population size following the initial founding event. It is likely the observed loss of diversity and the significant differentiation observed between the Umatilla herd and its source was a function of the low number of founders and stochastic losses of diversity in subsequent generations. We observed significant haplotypic and genotypic differentiation between the reintroduced population and its source (GST = 0.063, FST = 0.078, p < 0.0...

THE CURRENT STATUS AND HISTORY OF RING-BILLED GULLS (LARUS DELAWARENSIS) IN MAINE

The Ring-billed Gull (Larus delawarensis) experienced a significant contraction of its range from the Great Lakes eastward during the nineteenth century, but it staged a remarkable recovery in the late twentieth century that continues to the present. A rapid increase in population size in Maine, indexed by Christmas Bird Counts and field sighting data, occurred from the early 1970s through the 1990s. The timing of population growth in Maine closely paralleled the growth and spread of breeding populations along the St. Lawrence River in Québec, and eastward into the Maritimes. At this time, Ring-billed Gulls also began to appear in greater numbers during summer on interior lakes in Maine. Breeding colonies are now known on two inland lakes.

The successful founder: genetics of introduced Carduelis chloris (greenfinch) populations in New Zealand

The amount and distribution of genetic variation in seven introduced New Zealand populations of Carduelis chloris were assessed at 40 loci using starch gel electrophoresis and compared with those in native European populations. Fewer alleles (1.45) and fewer polymorphic loci (33 per cent) were detected across the introduced populations than across native populations (1.75, 55 per cent), reflecting the narrow geographical origin of the introduced populations. There was no evidence for severe inbreeding or genetic drift as the levels of average heterozygosity (H = 0.025), percentage polymorphic loci (P = 16.9) and average number of alleles per locus (A = 1.22) were indistinguishable from levels observed within European populations (77 = 0.025, P =14.1, A = 1.19). Furthermore, introduced populations were genetically less weakly differentiated (FST = 0.022) than native populations (FST = 0.041), indicating that little genetic drift has been involved in the colonization of the new range. Similar levels of genetic variability in native and introduced greenfinch populations are consistent with theoretical expectations as the founder population size was relatively large (>60 individuals) and a rapid increase in population size directly after colonization was documented. A review of earlier studies on introduced birds also revealed that reductions in levels of genetic variability seem to be inversely proportional to the size of the founder population, and that less variation has been lost if the rate of population growth directly after introduction was fast.

Heterogeneous Responses of Small Mammals to an El Nino Southern Oscillation Event in Northcentral Semiarid Chile and the Importance of Ecological Scale

A prolonged El Nino Southern Oscillation (ENSO) event during 1991–1992 with three times the normal annual 85-mm rainfall was accompanied by major changes in numbers of small mammals at a semiarid Mediterranean site in northcentral Chile. Several demographic patterns were evident. Akodon olivaceas , an omnivore, had a rapid increase in population size of more than an order of magnitude. Phyllotis darwini , a granivore-herbivore, showed somewhat delayed, smaller increases superimposed on annual oscillations. Octodon degus , an herbivore, showed a delayed response with larger increases and extended breeding in 1992–1993. Finally, Oligoryzomys longicaudatus , a granivore, experienced increases during both a dry (1990, ppt = 32 mm) and a wet year (1992). Other species such as Abrothrix longipilis, Abrocoma bennetti , and Thylamys elegans had smaller, delayed demographic responses. Reproductive rates for the first three species were higher due to the ENSO event only in O. degus males and P. darwini as a quadratic function of time. Survival rates of all four principal species were significantly greater during the 1991–1992 ENSO. Finally, average movement between captures was lower during ENSO years, suggesting behavioral changes. Explanations for these patterns include rainfall-related increases in food-resource levels ( A. olivaceus and P. darwini ), the importance of source-sink processes in vagile species from more mesic, adjacent habitats ( O. longicaudatus ), and delayed responses to extrinsic events in species with long gestation ( O. degus, A. bennetti ). The heterogeneity of species responses suggests different capabilities for small mammals to respond to an extrinsic, large-scale event, and it emphasizes the importance of long-term studies in semiarid systems.

Population genetics of induced mutations

The contribution of induced mutations to the burden of genetic disease in the context of population genetics is considered. A clear distinction is made between the effects of genetic disease and mutational events. Much of the existing burden of genetic disease is a consequence of mutations that occurred in the past. The problem of distinguishing between spontaneous and induced mutations is discussed. Molecular genetics techniques are blurring the definitions of these terms. Classical population genetics shows that the frequency of affected individuals will reach an equilibrium depending on the mutation rate and the selective pressure against affected individuals. Increasing the mutation rate or reducing the selective pressures would result in a new equilibrium with an increase in the frequency in subsequent generations of affected individuals with dominant and X-linked mutant alleles. The increase in the number of recessive mutant alleles would be much slower and take many generations to reach the new equilibrium level. One assumption behind such equilibria is random mating. Changes in human demography with a rapid increase in population size, the breakup of small, relatively inbred subpopulations, and relaxed selective pressures will lead to a new equilibrium for recessive genes at probably higher frequencies. These factors will be the major contributors to increasing the burden of recessive genetic disease by increasing the total numbers of cases. The proportion of the population with a genetic disease will also continue to grow as a greater proportion of the population survives to late middle age and succumbs to diseases associated with old age, such as cancer, circulatory disease, dementias, and diabetes, each of which is likely to have a genetic component.(ABSTRACT TRUNCATED AT 250 WORDS)

Population Characteristics of the Invading White Perch ( Morone Americana) in Western Lake Erie

The white perch ( Morone americana) is an East Coast estuarine species that invaded Lake Erie in the 1950s, but did not increase in abundance until the mid 1970s. We studied its distribution and population dynamics in western Lake Erie during this period of rapid increase in population size. White perch spawned in riffle areas of tributary streams of western Lake Erie during late April, and then moved downstream into the lake. They were abundant in nearshore and reef habitats throughout most of the year, although a few were collected in deep offshore areas. Increasingly strong year classes were produced each year in 1980–1984. The age structure of the population reflected a surge in recruitment in the 1980s; fish of age–1 and age–2 were abundant, but older fish were still rare. White perch in western Lake Erie grew faster and matured earlier than those in most other populations, but growth rates appeared to be declining as the population expanded. White perch can be expected eventually to colonize suitable habitats throughout the Great Lakes.

Simulation of the effects of changing population size on the genetic structure of Western Ireland.

During the 1800's, the population of Ireland underwent a rapid increase and subsequent decrease in population size. The effects of this change upon population structure were assessed using a simulation of the isolation by distance model and comparing the results to those obtained assuming constant population size. These results indicate that changes in within-group genetic similarity (kinship) brought about by a rapid increase in population size are cancelled by the effects of a rapid decrease in population size. Parameters of the isolation by distance model are hardly affected by population size changes. These results suggest that violation of the assumption of constant population size for population structure models may not be that serious when population size changes rapidly and in both directions.