Family Immigration Articles

In the small Irish village of Carrigaholt, the traditional pub is named the Long Dock. The owners are from a family that has resided in Carrigaholt as long as records have been kept. The only thing that has changed in recent years is the personnel. The two bartenders are Lithuanians, and the tables are waited on by two Poles. The kitchen staff is entirely Latvian. The visiting American writer Thomas Lynch notes that on St. Patrick’s day, 2006, the crowd in the Long Dock seems to be enjoying the pints of stout as usual.

Population census size ( ) and effective population sizes ( ) are two crucial parameters that influence population viability, wildlife management decisions, and conservation planning. Genetic estimators of both and are increasingly widely used because molecular markers are increasingly available, statistical methods are improving rapidly, and genetic estimators complement or improve upon traditional demographic estimators. We review the kinds and applications of estimators of both and , and the often undervalued and misunderstood ratio of effective-to-census size ( ). We focus on recently improved and well evaluated methods that are most likely to facilitate conservation. Finally, we outline areas of future research to improve and estimation in wild populations.

Eight variable regions (microsatellites, insertion/deletion and duplication regions) from the plastid DNA genome were analyzed for 91 populations belonging to ssp. and closely related taxa. A total of 36 composite plastid haplotypes were found. The two dominating haplotypes had a clear geographic distribution suggesting at least two separate immigration routes into Scandinavia after the last glaciation: one southwestern route and one or two southeastern routes. ssp. could not be clearly separated from any of the other taxa included in the study except for ssp. . The morphologically similar taxa ssp. , ssp. and ssp. showed no genetic differentiation, and therefore we suggest an amalgamation of the three taxa into one broadly circumscribed subspecies; ssp. . The plastid data also revealed incidents of hybridization and possible introgression between ssp. and other members of the genus, e.g., .

Mammal species characterized by highly fluctuating populations often maintain genetic diversity in response to frequent demographic bottlenecks, suggesting the ameliorating influence of life history and behavioral factors. Immigration in particular is expected to promote genetic recovery and is hypothesized to be the most likely process maintaining genetic diversity in fluctuating mammal populations. Most demographic bottlenecks have been inferred retrospectively, and direct analysis of a natural population before, during, and after a bottleneck is rare. Using a continuous 10-year dataset detailing the complete demographic and genetic history of a fluctuating population of golden-mantled ground squirrels (), we analyzed the genetic consequences of a 4-year demographic bottleneck that reduced the population to seven adult squirrels, and we evaluated the potential “rescue effect” of immigration. Analysis of six microsatellite loci revealed that, while a decline in allelic richness was observed during the bottleneck, there was no observed excess of heterozygosity, a characteristic bottleneck signature, and no evidence for heterozygote deficiency during the recovery phase. In addition, we found no evidence for inbreeding depression during or after the bottleneck. By identifying immigrants and analyzing their demographic and genetic contributions, we found that immigration promoted demographic recovery and countered the genetic effects of the bottleneck, especially the loss of allelic richness. Within 3 years both population size and genetic variation had recovered to pre-bottleneck levels, supporting the role of immigration in maintaining genetic variation during bottleneck events in fluctuating populations. Our analyses revealed considerable variation among analytical techniques in their ability to detect genetic bottlenecks, suggesting that caution is warranted when evaluating bottleneck events based on one technique.

An emerging pattern is that population densities of generalist rodents are higher in small compared to large forest patches in fragmented landscapes. We used genetically based measures of migration between patches to test two dispersal-based hypotheses for this negative density-area relationship: (1) emigration rates from small patches should be relatively lower compared to large patches (“inhibited dispersal hypothesis”), or (2) immigration rates should be higher into small than large patches (“immigration hypothesis”). Neither hypothesis was supported using data on dispersal inferred from eight microsatellite loci for 12 populations of in six small (1.3–2.7 ha) and six large (8–150 ha) forest patches. Emigration rates were not lower from and immigration rates were not higher into small than large patches. In fact, contrary to both hypotheses, emigration rates were higher from populations of in small compared to large patches. Based on a combination of genetic and field data, we speculate that higher reproduction in smaller patches resulted in higher densities which led to higher emigration rates from those patches. Rates of reproduction (presumably driven by better habitat conditions in smaller patches), rather than dispersal, seems to drive density differences in forest patches. We conclude that smaller forest patches within an agricultural matrix act as a source of individuals, and that migration rates are fairly high among forest patches regardless of size.

Many recent studies of intraspecific geographic variation in maternally inherited chloroplast DNA (cpDNA) in European trees have revealed haplotype distributions that can be interpreted in terms of scenarios of postglacial migration and range expansion. However, there is still a lack of comparable information from widespread herb species. In the present study, we investigated the geographic distribution of cpDNA variation in 124 populations, covering a large part of the range of the widespread, dioecious, European herb, . PCR-RFLP analysis revealed 24 different cpDNA haplotypes. As in the majority of European tree species, the large-scale geographic distributions of the most common haplotypes suggest that the species colonized Europe from more than one geographic source. Material from 16 populations of and five hybrid populations was also included in the study for comparative purposes. Five out of seven haplotypes detected in were shared with . The similarity of the geographic distributions of the shared haplotypes in both species is consistent with a history of past and/or recent interspecific hybridization and introgression between these closely related plants. The two haplotypes detected only in were present in populations in the Mediterranean region – on the southern margin of the species’ area of sympatry, or outside the range of .

The rational assembly of microbial communities to perform desired functions would be of great practical benefit to society. Broadly speaking, there are two major theoretical foundations for microbial community assembly: one based on island biogeography theory and another based on niche theory. In this study, we compared a parameter from each theory (immigration rate and sustainability, respectively) to ascertain which was more influential in establishing a functional bacterial population in phenol degrading activated sludge over a 30-day period. Two bacterial strains originally isolated from activated sludge, but differing in their ability to sustain a population in this environment, were repeatedly added to activated sludge reactors at different doses. The resulting size of each population was monitored by competitive polymerase chain reaction. Large, unexpected, yet reproducible fluctuations in population sizes were observed. Irrespective of this, difference in the ability to sustain a population in this environment, overshadowed the influence of 100-fold differences in immigration rate.

Mosquito distribution in the immigration bird-nested area, Pathumthani province, was investigated from August to December in 2006. Mosquitoes were collected by using CO-baited Centers for Disease Control light traps in which dry ice was used as a source of CO to attract mosquitoes. Six traps were operated from 4 p.m. until 7 a.m. on each study day. Four genera, which were , , , and with 14 species of mosquitoes were collected. (13.94–59.41%) and (32.87–70.30%) were most collected species in this area for every month. Other two species with moderate distribution in this area were (0.76–3.30%) and (1.55–11.36%). Polymerase Chain Reactions were performed for testing infection in . and . only. Fifty-four percent (15/28 pools) of . and none (0/20 pools) of . were positive for infection. infection in other mosquito species collected in this and other areas need to be investigated to understand species and geographic variation of infection in mosquitoes in nature.

DNA fingerprinting without doubt represents one of the most significant advances in forensic science this century. Central to this technology, which is based on the analysis of the genetic component of cells, is the use of DNA probes to regions of the human genome that exhibit great variability between individuals (). These probes fall into two main categories. The first group comprises those that can detect a large number of these “hypervariable” loci simultaneously, namely multilocus probes (MLPs). On autoradiography, these give rise to a band pattern that is reminiscent of the bar code on supermarket goods, the main advantage of which is that a single such test provides a lot of information very rapidly. MLPs are, therefore, the probes of choice when the amount of material for testing is not limiting, e.g., a blood sample for paternity testing. In many forensic cases, however, the material evidence available for testing is minute, such as a few hair roots or a tiny semen stain, and the situation is often complicated by the presence of tissue from more than one person.

The evolution of social monogamy in larger mammals is difficult to explain because males usually do not invest much in direct offspring care and might achieve greater fitness by deserting a pregnant female to reproduce with additional females elsewhere. It has been hypothesized that socially monogamous males remain with the female year-round to protect their offspring from infanticide by new immigrant males. We investigated this idea by analyzing all cases of infant loss in a wild population of white-handed gibbons (; Primates), in which most groups were socially monogamous and some polyandrous (137.5 group years). We examined the influence of (a) male intruder pressure on male immigration rates and (b) the presence of a new male in the group on infant loss. We found no relation between intruder pressure and male immigration rates. Infant loss was lowest (4.5%) for stable monogamy (probable father stayed from conception through infancy) and intermediate (25.0%; ?=?0.166) for stable polyandry. If a new male immigrated after conception, however, the infant was lost in all cases (?<?0.01) independent of the presumed father’s presence. Overall, 83.3% of infant losses were associated with the presence of a presumably unrelated male. Although the sample size is small, our results provide the first true support for the idea that the risk of infanticide is an important factor in the evolution of social monogamy in larger mammals.

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