Population Size

A significant proportion of the population in sub-Saharan Africa live in the rural areas, with the majority living on less than US$1 per day. Access to electricity is considered an essential element in the sustainable development of rural areas and an enabler for countries to achieve their Millennium Development Goals. This paper contributes the first analytical study of the socio-economic factors which have a significant impact on rural electrification (RE) development in sub-Saharan Africa. The study employs cross-sectional data for 24 of the 47 countries in the sub-Saharan region and finds factors including the Human Development Index, wealth distribution, institutional development and urban population size of a country to have a significant impact on RE development. A detailed policy survey of four countries from the sample; two countries categorised as over-performing (Nigeria and Madagascar) and two as under-performing (Tanzania and Chad), highlights that collaboration with in...

Pollen immigration can offset the effects of genetic drift and inbreeding in small populations. To understand the genetic consequences of forest fragmentation, estimates of pollen flow into remnant fragments are essential. Such estimates are straightforward for plants with singly sired, multiseeded fruits, since the pollen donor genotype for each fruit can be unambiguously reconstructed through full-sib genealogical analyses. Allozyme analyses were used to estimate pollen donor numbers from the progeny of fruits of the tropical dry forest tree Enterolobium cyclocarpum in a small (9.8 ha) fragmented population (N = 11) over three reproductive seasons (1994, 1995, and 1996). These analyses indicate that each tree receives pollen from many pollen donors. When data are pooled for the site, estimated maximum pollen donor pool sizes in all years exceed the number of individuals (56) in the 227 ha study area. Although unidentified pollen donors may be located as close as 250 m to the study...

We use six decades of catch-at-age data for perch (Perca fluviatilis) and pike (Esox lucius) in Windermere (UK) to estimate age-and sex-specific population sizes, natural mortalities and catchabilities in both species. Population sizes are estimated by fitting age structured population models to the catch-at-age data using standard maximum likelihood methods. We validate our methods using data simulations, and use our estimates of vital rates (natural mortality, recruitment and catahability) to address important aspects of fisheries biology. ...

Selection of GI-Sb coupling heterozygotes was carried out for more than one hundred generations commencing with six independent lines drawn from a common base population. Population sizes were eight, sixteen and forty-eight parents per generation. The effect of natural selection on recombination value was measured by sampling and testing females at varying intervals of time. There was a significant reduction in percentage recombination between GZ and Sb from fifteen to a level between five and ten in four out of six of the original lines. In most cases this reduction occurred rather rapidly after the initiation of the experiment. In the remaining two lines there was no significant decrease in recombination value; there was, however, a significant increase in at least one subline of this group. The rapid rate of change of recombination value is most readily explained by the presence of a recombination modifying gene which is linked to the modified region. Genetic random drift was aga...

Greater bamboo lemurs (Prolemur simus) are endemic to Madagascar and are the only recognized species within their genus. The IUCN lists the species as critically endangered, with very few confirmed distribution records and <200 individuals known in the wild. With the aim of contributing to its conservation, we attempted to find previously unknown sites containing the species. Working closely with local communities, and basing our methodology on the gathering of local knowledge, we surveyed 44 sites in and around the Ankeniheny-Zahamena Corridor. We found evidence of the presence of Prolemur simus at 18 sites. We made direct sightings at 6 sites, of a total of 65 confirmed individuals, and identified their characteristic feeding remains at the other sites. Twelve of the sites are located in midaltitude rain forest within the corridor, and 6 lie in isolated and degraded lowland areas outside the corridor. These discoveries more than double the number of sites where the species is known to occur, and extend its known range 85 km further north. We identified numerous threats to the newly discovered sites, including hunting pressure, habitat destruction, habitat disturbance, and habitat fragmentation. Demographic factors related to small population sizes and population isolation may also impact the viability of the populations. Our results illustrate the benefits of systematic gathering of local knowledge when searching for rare or secretive primates.

... Tres carcasas fueron infestadas con un parásito patogénico, Angiocaulus gubernaculatus, que no se encuentra en las poblaciones de zorros en las islas de San Nicolás, San Clemente, Santa Catalina, Santa Cruz o Santa Rosa, y 2 carcasas tuvieron Uncinaria ... Cheri A. Jones. ...

Although stony corals are most frequently studied on high-relief reef structures, many coral species occur in a wide variety of nearshore tropical habitats, including mangrove creeks, seagrass beds and rocky platforms. This study estimated overall population size, potential reproductive output, and population structure for several species across sandy-bottom, hard-bottom, and patch reef habitats. The density of coral colonies, area of available habitat, and size distribution of resident Siderastrea radians, Favia fragum, and Diploria clivosa colonies were recorded for several island bank systems across habitat types in the central Bahamas. Nearshore patch reefs generally exhibited larger population sizes and higher density of colonies, and contained more larger or older colonies. Nearshore hardbar communities had smaller population sizes and a lower density of colonies, and supported more small colonies, which may either be recruits or asexual clones. High numbers of larger colony s...

One of the key stimulators of intestinal development in the chick is physical exposure to feed, while feed withholding delays the onset of gut development. A delay of 24–72 h in onset of feeding is quite common in the poultry industry due to variation in hatching time and hatchery treatments. As intestinal development occurs in concert with the development of the gut associated lymphoid tissue (GALT), we investigated the effects of short term feed withholding on development of GALT in broiler hatchlings. GALT activity was determined by antibody production (systemic and locally in the gut), distribution of B and T lymphocytes in the gut, expression of lymphocyte specific genes, and distribution of B and T lymphocytes in the cloacal bursa. Our findings show that while development of GALT in the foregut (duodenum, jejunum, ileum) was only slightly and temporarily impeded by feed withholding, GALT activity in the hindgut and the gut-related cloacal bursa was significantly delayed during the first 2 weeks of life: Systemic and intestinal antibody responses following rectal immunization to antigen were lower, colonization of the hindgut (cecum and colon) by T and B lymphocytes was delayed, as well as the expression of chIL-2 mRNA in hindgut T lymphocytes. We also found that the increase of B and T population size in the cloacal bursa was delayed with time. Full recovery occurred from 2 weeks of age. The 2-week vulnerable period should be seriously considered in circumstances where hatchlings are in transit for extended periods from hatcheries to farms.

A good selection of the internal parameters of a ge netic algorithm may reduce the optimization speed considerably. We studied the effects of two key par ameters, namely population size and relative elit- ism, on the optimization speed and reliability. We found that changing one parameter can be compen- sated for changing another. By penalizing for the u nreliability of

The current geographical distribution of the Mediterranean monk seal Monachus monachus colony inhabiting the Cabo Blanco peninsula (Western Sahara-Mauritania) is described. Its distribution range has apparently not changed since surveys conducted in 1984–1988. Sightings of adults on the Tarf el Guerguerat coast, 20 km north of the known breeding caves, suggests the existence of other possible breeding groups further north. Two caves used by the seals are described for the first time. A review of historical trends in cave occupation by seals made it possible (1) to locate the so-called ‘maternity cave’, last reported in 1949; and (2) to establish that the colony, since its discovery, has occupied at least eight caves, five of which have collapsed. An index of population size based on counts of individuals of identified morphological types indicates that, during 1993–1994, the colony was composed of c.113–165 individuals (excluding pups), a larger number than previously assumed. Counting of seals at times of maximum haul-out is proposed as a tool to monitor population trends, although it is considered unreliable for estimating absolute numbers.

A simultaneous survey of 14 protein loci, together with frequencies and within- and between-population allelism rates of lethal chromosomes, was carried out in five (four Japanese and one Korean) natural populations and one cage population of Drosophila melanogaster. It was found that lethal allelism rates decrease rapidly as geographic distance between two populations increases, while variation at protein loci shows a remarkable similarity over all populations examined. These findings suggest that there are very high levels of gene flow in these natural populations and that selection at protein loci which can maintain substantial geographic variation, if present, is overshadowed by gene flow. There is no indication that invasion of D. melanogaster to the Far East occurred so recently that the frequencies of lethal chromosomes are still in nonequilibrium.

Horseshoe crabs have recently gained popularity as new exotic delicacies in Malaysia, especially in Johor. It has been reported and claimed by some fishermen that horseshoe crabs, particularly females, are being transported in bulk to Thailand. This claim has sparked interest to identify population size and study the behaviour of horseshoe crabs along the east coast of Peninsular Malaysia in an attempt to determine the effect of this demand on the existing population. A study was carried out from December 2011 to March 2012 to determine the coastal horseshoe crab Tachypleus gigas population size in Chendor and Cherating, Pahang, about 10 km apart on the east coast of Peninsular Malaysia, using a Capture-Mark-Recapture method. The sampling was carried out three times at both sites. The population size was calculated using Bailey’s Triple Catch formula with the assumption of an open population. The horseshoe crabs’ ‘traveling distance’ was also determined by attaching numbered, white button tags, each bearing the researcher’s phone number, to a total of 99 horseshoe crab individuals (61 in Chendor, 38 in Cherating). The total estimated populations were 7,140 in Chendor and 9,900 in Cherating. The two populations were found to be interchangeable as the tagged animals from Chendor were recaptured in Cherating and vice versa, thus confirming emigration and immigration. About 25 % of tagged animals were recaptured in various places (at Chendor, Cherating and also outside both locations) as reported by fishermen. Animals tagged in Cherating were caught in a few locations in Pahang, including Tanjung Lumpur which is more than 50 km to the south. Most recaptures (40 %) were from different locations remote from the site where the horseshoe crabs were tagged and released. This study is on-going and notifications are still expected regarding the future location of the tagged animals.

Episodes of population growth and decline leave characteristic signatures in the distribution of nucleotide (or restriction) site differences between pairs of individuals. These signatures appear in histograms showing the relative frequencies of pairs of individuals who differ by i sites, where i = 0, 1, . . . . In this distribution an episode of growth generates a wave that

This paper examines the relevance of the concept of economic vulnerability for low income countries, a topic of recent concern in several international bodies. It first proposes some conceptual clarifications and a method to build an internationally comparable indicator. Three factors of vulnerability are identified: shocks, exposure and resilience or capacity to react (the first two ones being more structural, the third one more related to policy). To measure the two main kinds of shocks (natural and external), proposed proxies are respectively the instability of agricultural production and the instability of the purchasing power of exports, while the (smallness of) the population size can be used as a proxy for (structural) exposure. To aggregate the various possible indicators of shocks and exposure in a composite index of structural economic vulnerability, weights can be drawn from their estimated impact on growth. Then selected issues related to the impact of vulnerability on g...

We analyzed whether, in democratic open societies, economic and demographic conditions allow sporting success at the aggregate level to be predicted. Theoretical considerations led to the hypothesis that the population size and gross domestic product (GDP) per capita should be important determinants of sporting success. Using regression analysis, we analyzed the influence of population size and GDP per capita on sporting success in Olympic Summer and Winter Games (1992 – 2010). Regarding the Olympic summer games, we found that the most powerful predictor is population size. In contrast, GDP per capita seems to play an important role as a predictor of sporting success with respect to the Olympic winter games.