Releases of biological control agents of insect pests on Easter Island (Pacific Ocean)

For half a century, agriculture on Easter Island has been affected by an increasing number of accidentally introduced insect pests. Due to the absence of natural enemies and other factors, these have reached high density levels which claimed for intensive use of pesticides. A project supported by the National Funds for Regional Development (FNDR) was established in 1984 to develop a biological control program against these pest species. Presently, 60 beneficial species have been introduced to control agricultural pests and flies that affect cattle and humans. Some of the natural enemies have established and are reducing pest populations thereby decreasing the requirement for insecticidal treatments. Fly density has also decreased noticeably. This can be attributed to the activity of natural enemies and dung beetles which compete with larval fly for food.     

Y-chromosome-Specific STR haplotype data on the Rapanui population (Easter Island)

Located in the south Pacific Ocean, Rapanui is one of the most isolated inhabited islands in the world. Cultural and biological data suggest that the initial Rapanui population originated from central Polynesia, although the presence of foreign or exotic genes in the contemporary population, as a result of admixture with Europeans and/or South Americans during the last two centuries, also has to be considered. To estimate the genetic affinities of the Rapanui population with neighboring populations, we analyzed seven microsatellite polymorphisms of the Y chromosome that recently have been indicated as useful in the study of local population structure and recent demographic history. Phylogenetic analysis of Rapanui Y-chromosome haplotypes identified two clusters. The largest cluster contained 60% of all haplotypes and is characterized, in particular, by the presence of the DYS19*16, DYS390*20, and DYS393*14 alleles, a combination found frequently in Western Samoa. The second cluster is characterized by the presence of the DYS19*14, DYS390*24, and DYS393*13 alleles, and these have a relatively high frequency in European and European-derived populations but are either infrequent or absent in native Pacific populations. In addition to the two clusters, one male is of haplogroup Q*, which is indicative of native American ancestry. The genetic structure of the current male population of Rapanui is most likely a product of some genetic contribution from European and South American invaders who mated with the indigenous Polynesian women. However, analysis of Rapanui's relationships with other Pacific and Asian populations indicates that, as in Western Samoa and Samoa, the population has experienced extreme drift and founder events.     

Development of pentaplex PCR and genetic analysis of X chromosomal STRs in Punjabi population of Pakistan

The X-STRs are important tools in forensic application, particularly in complex cases of kinship testing. In deficiency paternity testing when alleged father cannot be typed, investigation of X-STR markers yields the desired information. Blood samples were collected from unrelated individual (118 females and 94 males) and 84 trios families (father, mother and daughter). DNA extraction from whole blood was performed with Phenol chloroform method. Five X-linked STR markers DXS6800, DXS7133, DXS6797, DXS981 and GATA165B12 were selected. The amplicons were analyzed through ABI 3100 Genetic Analyzer. Pentaplex PCR system was developed for multilocus amplification at the same time. For each locus 4–9 alleles were noted. Altogether, 32 alleles were observed from five markers. Eighty-four trios families were analysed to check the mutation rate and no mutation was observed. Stutter peaks were observed maximum at locus DXS6797 (12.44%) while the minimum at locus DXS7133 (4.5%). For sensitivity study, amplification of X chromosomal short tandem repeats loci was successfully performed using 0.15 ng quantity of DNA as template. In conclusion; this pentaplex represents a convenient method to study X chromosome markers. It works with reasonable amounts of DNA and is suitable for paternity cases.     

The effects of island area, isolation and source population size on the presence of the grayling butterfly Hipparchia semele (L.) (Lepidoptera: Satyrinae) on British and Irish offshore islands

Records of Hipparchia semele on British and Irish islands have been modelled against island area, isolation (sea and land distance) and the size of the nearest potential source populations. All three variables have been found to contribute significantly to the presence or absence of H. semele on the islands. Isolation is a more significant predictor than island area. This result differs from the multiple species case where area was found to be a more important influence than isolation. Records on islands are also shown to depend on the size of populations at the nearest sources; this underpins the relationships identified for the multiple species case, first, between the number of species on islands and at nearest sources and, second, between the incidence of species on islands and at nearest sources. There are clear indications that smaller islands may become increasingly marginalized for H.semele; with ongoing habitat loss, because isolation increases and source populations become sparser, the probability of H. semele recolonizing islands also decreases.     

Dermatoglyphs of the population from the island of Rab (Croatia)

As a part of multidisciplinary anthropological research of population structure on Croatian island of Rab, finger and palm prints from 548 inhabitants (225 males and 323 females) of six villages on Rab were collected and their qualitative dermatoglyphic traits analysed. We calculated frequencies of patterns (whorls, loops and arches) on fingers, frequencies of patterns in the interdigital areas, Thenar and Hypothenar of the palms and frequencies of position of the axial triradius “t” (t, t′, t″ and other t) for male and female population of each village. Statistical analysis was performed by using Chi-square test, and Hiernaux Δg biological distances between pairs of populations were determined. The results of this study show existence of statistically significant diversity among the village populations in qualitative dermatoglyphic traits both for males and females. This variability found in the population from the island of Rab can be explained by influence of the microevolutionary factors through endogamy and the way of migrational flow on the island in course of history. Subpopulation of Barbat in the eastern part of Rab, which is the closest to the mainland, is probably different because of a high migration rate from the mainland during the past centuries. Subpopulations of Lopar, Supetarska Draga and Kampor were the most isolated subpopulations, situated in three different valleys in the west of Rab, and therefore genetic drift could have been more influential there and responsible for noticed differences.     

Migration and inbreeding: the importance of recipient population size for genetic management

Sewall Wright demonstrated 70 years ago thatthe number of migrants required to maintainspecified levels of gene flow (i.e. avoidexcessive inbreeding) is virtually independentof the size of the recipient population. According to conventional wisdom, this idea isvalid provided population size exceeds 20. Itis well known that this independence implicitlyassumes that a population's effective size(N _e) is equal to its census size(N). However, it is not obvious whetherindependence between the required number ofmigrants (to avoid excessive inbreeding) andpopulation size constitutes a reasonableassumption for real populations of conservationconcern. Relying on empirical data, wedemonstrate that for real populations, theassumption (i.e. N _e = N) isroutinely violated to a degree such that therequired number of migrants is stronglydependent on the size of the recipientpopulation. Because a population's effectivesize (N _e) is typically much smallerthan its census size (N), the number ofmigrants required to avoid inbreeding isactually dependent on N even when it isconsiderably greater than 20. For example,when N _e/N = 0.1, the number ofmigrants required to maintain the inbreedingcoefficient (F) at 0.2 doubles (from 4 to8) as N increases from 9 to 60. Similarly, when N _e/N = 0.05, thenumber of migrants required increases by 50%as N increases from 18 to 45, andincreases again by 50% as N increasesfrom 45 to 260. Thus, for populations muchlarger than 20, the required number of migrantsincreases asymptotically with N, anddramatically so when N _e/N1. Simple conventions regarding the requisitenumber of migrants may not apply to manypopulations of conservation concern. Geneticmanagement should routinely rely on models thatexplicitly account for this and other recentconsiderations. Failure to do so mayjeopardize the viability of populations thatare sensitive to altered levels of inbreeding.     

Migration, isolation and hybridization in island crop populations: the case of Madagascar rice

Understanding how crop species spread and are introduced to new areas provides insights into the nature of species range expansions. The domesticated species Oryza sativa or Asian rice is one of the key domesticated crop species in the world. The island of Madagascar off the coast of East Africa was one of the last major Old World areas of introduction of rice after the domestication of this crop species and before extensive historical global trade in this crop. Asian rice was introduced in Madagascar from India, the Malay Peninsula and Indonesia approximately 800-1400 years ago. Studies of domestication traits characteristic of the two independently domesticated Asian rice subspecies, indica and tropical japonica, suggest two major waves of migrations into Madagascar. A population genetic analysis of rice in Madagascar using sequence data from 53 gene fragments provided insights into the dynamics of island founder events during the expansion of a crop species' geographic range and introduction to novel agro-ecological environments. We observed a significant decrease in genetic diversity in rice from Madagascar when compared to those in Asia, likely the result of a bottleneck on the island. We also found a high frequency of a unique indica type in Madagascar that shows clear population differentiation from most of the sampled Asian landraces, as well as differential exchange of alleles between Asia and Madagascar populations of the tropical japonica subspecies. Finally, despite partial reproductive isolation between japonica and indica, there was evidence of indica/japonica recombination resulting from their hybridization on the island.     

Density effects on life-history traits of an island lizard population

Long-term monitoring of life-history traits and the effects of density upon them were studied in an island population of the lizardEumeces okadae. Although life-history traits such as clutch size, egg size and the proportion of mature reproductive females varied little over 7 years in the intact population, manipulation of density to simulate decreased population density enhanced juvenile growth rate, age at first reproduction, frequency of female reproduction and size-specific clutch mass. In particular, the proportion of mature females reproducing annually increased almost 10 times from 5.6% to 53.8% after the removal of some lizards. However, body size at first reproduction and egg size were almost identical under both high and low density conditions. This study suggests that there were strong density-dependent effects on several life-history traits and thatE. okadae attained a density close to the carrying capacity of the environment.     

Simplified song in an island population of the bush warbler Cettia diphone

Song complexity and the repertoire of the bush warbler Cettia diphone were studied in an island and a mainland population in Japan. The song complexity (number of modulations in a song) was lower in the island population than in the mainland one. On the other hand, the repertoire size (number of song types per male) was larger on the island. Founder effect probably does not influence the island song because colonization occurred a very long time ago. Sound transmission properties of the habitat and weak selection pressure for interspecific identification might have influenced the island song, but these cannot elucidate the simpler song on the island. There is a possibility that social conditions affect song complexity in the populations; the highly polygynous mating system of the mainland population yields strong selection pressure toward complex song through acquisition of mates and/or establishment of quality territories. On the other hand, variable songs on the island seem to be affected by cultural mutation. Received: September 3, 1999 / Accepted: December 9, 1999     

Differentiation under isolation and genetic structure of Sardinian hares as revealed by craniometric analysis,mitochondrial DNA and microsatellites

Hares (Lepus capensis Linnaeus 1758) were probably introduced into Sardinia in historical times. Previous studies indicated North Africa as the most likely source area but did not exclude the occurrence of hybridization events with continental brown hares (L. europaeus Pallas 1778) perhaps introduced for hunting purposes. We implemented both morphometric and genetic approaches to verify the genetic isolation of the Sardinian population. Specifically, we conducted a multivariate analysis of craniometric data and analysed 461 bp of the mitochondrial control region and 12 autosomal microsatellites in Sardinian hares, using North African cape hares and European brown hares as reference populations. Sardinian hares displayed a peculiar skull shape. In agreement, both nuclear and mitochondrial markers remarked the distinctiveness of this population. Observed and expected heterozygosity were 0.52 and 0.61, while haplotype and nucleotide diversity were 0.822 and 0.0129. Self‐assignment based on Bayesian cluster analysis was high (average membership 0.98), and no evident signs of introgression from continental brown hares were found. Our results support the hypothesis that the Sardinian hares have been introduced from North Africa, remained genetically isolated since the founding event and evolved independently from the source population. This long‐lasting isolation and the consequent genetic drift resulted in a differentiation, perhaps accompanied by an adaptation to local environmental conditions.     

A population genetic analysis of migration: the case of the noctule bat (Nyctalus noctula)

Although rarely assessed, the population genetics of hibernating colonies can help to understand some aspects of population structure, even when samples from nursery or mating colonies are not available, or in studies of migration when both types of samples are available and can be compared. Here we illustrate both points in a survey of mitochondrial DNA (mtDNA) control region sequences used to study the population genetics of hibernating colonies of a migrating species, the noctule bat (Nyctalus noctula). Lacking samples from Scandinavian nursery colonies, we use a North European hibernacula to suggest that Scandinavian populations are isolated from Central and East European colonies. Then, we compare genetic diversities of nursery and hibernating colonies. We find a significantly higher haplotype diversity in hibernacula, confirming that they consist of individuals from different nursery colonies. Finally, we show that pairwise comparisons of the haplotype frequencies of nursery and hibernating colonies contain some information on the migration direction of the noctule bat.     

The effects of cyclic dynamics and mating system on the effective size of an island mouflon population

The Haute Island mouflon (Ovis aries) population is isolated on one small (6.5 km2) island of the remote Kerguelen archipelago. Given a promiscuous mating system, a cyclic demography and a strong female-biased sex ratio after population crashes, we expected a low effective population size (Ne). We estimated Ne using demographic and temporal genetic approaches based on genetic information at 25 microsatellite loci from 62 and 58 mouflons sampled in 1988 and 2003, respectively. Genetic Ne estimates were higher than expected, varying between 104 and 250 depending on the methods used. Both demographic and genetic approaches show the Haute Island Ne is buffered against population crashes. The unexpectedly high Ne likely results from the cyclic winter crashes that allow young males to reproduce, limiting the variance of male reproductive success. Based on individual-based simulations, we suggest that despite a strongly female-biased sex ratio, the effects of the mating system on the effective population size more closely resemble random mating or weak polygyny.     

Origin of modern humans in East Asia: clues from the Y chromosome

East Asia is one of the most important regions for studying modern human origin and evolution. A lot of efforts have been made to detect the genetic diversity and to reconstruct the evolutionary history of East Asians, especially using Y chromosome genetic data, in recent years. The Y chromosome data supports the African origin of modern humans in East Asia and the later migration to East Asia through the southern tropic coastline route, and then the northward migration occurred, leading to peopling of the main continent. The genetic data of the Y chromosome reflects a clear prehistoric evolution and migration course of East Asians. As well, the Y chromosome data of East Asians provides clues to elucidate modern human origins and evolution in the neighboring regions, i.e. America, Oceania and the Pacific Islands.     

Origin of modern humans in East Asia: clues from the Y chromosome

East Asia is one of the most important regions for studying modern human origin and evolution. A lot of efforts have been made to detect the genetic diversity and to reconstruct the evolutionary history of East Asians, especially using Y chromosome genetic data, in recent years. The Y chromosome data supports the African origin of modern humans in East Asia and the later migration to East Asia through the southern tropic coastline route, and then the northward migration occurred, leading to peopling of the main continent. The genetic data of the Y chromosome reflects a clear prehistoric evolution and migration course of East Asians. As well, the Y chromosome data of East Asians provides clues to elucidate modern human origins and evolution in the neighboring regions, i.e. America, Oceania and the Pacific Islands.     

Analysis of 31 STR loci in the genetic isolate of Carloforte (Sardinia, Italy)

The genotypes of 31 autosomal short tandem repeat loci in the population of Carloforte were analyzed, these representing a linguistic and genetic isolate located on the island of Sardinia (Italy). The markers span the entire length of chromosomes 19, 20, 21 and 22. Allele frequencies and statistical parameters were presented for all loci. Observed heterozygosity ranged from 0.279 to 0.884, and polymorphism information content from 0.552 to 0.886. All but two loci showed Hardy-Weinberg equilibrium after Bonferroni correction. The 31 short tandem repeat loci examined in the present work provide additional data on the genetic structure of the Carloforte population.     

Genetic isolation of a now extinct population of bottlenose dolphins (Tursiops truncatus)

A number of dolphin species, though highly mobile, show genetic structure among parapatric and sometimes sympatric populations. However, little is known about the temporal patterns of population structure for these species. Here, we apply Bayesian inference and data from ancient DNA to assess the structure and dynamics of bottlenose dolphin (Tursiops truncatus) populations in the coastal waters of the UK. We show that regional population structure in UK waters is consistent with earlier studies suggesting local habitat dependence for this species in the Mediterranean Sea and North Atlantic. One genetically differentiated UK population went extinct at least 100 years ago and has not been replaced. The data indicate that this was a local extinction, and not a case of historical range shift or contraction. One possible interpretation is a declining metapopulation and conservation need for this species in the UK.     

Genetic analysis reveals population structure and recent migration within the highly fragmented range of the Cross River gorilla (Gorilla gorilla diehli)

Recently developed methods of individual-based analysis of genetic data allow an unprecedented opportunity to understand the relationships among fragmented populations. By defining population structure and identifying migrant individuals, such analyses can provide a framework to aid in evaluating the threats posed by inbreeding and reduced genetic variability as a consequence of limited gene flow among fragments. Here we investigate population structure in the critically endangered Cross River gorilla (Gorilla gorilla diehli) by applying a suite of individual-based analyses to data obtained from between one-quarter and one-third of the estimated total population through the use of noninvasively collected DNA samples. The population structure inferred using data from 11 autosomal microsatellite loci was broadly consistent with geography and habitat fragmentation, but showed no simple isolation-by-distance effects. In contrast to previous field surveys, which suggested that all gorilla localities were isolated from one another, we infer low levels of gene flow and identify migrants between habitat fragments as well as individuals of admixed ancestry, suggesting persistent recent reproductive contact between many of the localities. These results are encouraging for the conservation of the Cross River gorilla population. Conservation efforts should strive to maintain connectivity between subpopulations that are still in migratory contact and attempt to restore connectivity where it has been lost.     

Migration patterns in a population of cottonmouths (Agkistrodon piscivorus) inhabiting an isolated wetland

Few studies have examined the spatial and temporal migration patterns of snakes to and from active-season habitats. We conducted a year-long population-level analysis of cottonmouth Agkistrodon piscivorus migration patterns by monitoring snakes entering and leaving a Carolina bay wetland that was encircled by a continuous terrestrial drift fence. Cottonmouths used the wetland during the active season and left the bay in the fall to overwinter in other habitats. Adults and juveniles did not differ in time of arrival at the bay but juveniles left the bay earlier than adults. Spatially, captures of adult cottonmouths entering and leaving the bay were distributed non-randomly, with capture peaks corresponding to the directions to the nearest permanent aquatic habitats. Juveniles' immigration patterns in the spring were biased in the same directions as those of the adults, but they left non-directionally in the fall. This suggests that neonates do not rely on adult scent trailing to locate hibernacula, and that in a region with moderate winter temperatures, suitable overwintering sites may not be a limited resource. Additionally, our study demonstrates that cottonmouths make extensive use of upland habitats and underscores the importance of both critical upland habitat and forested corridors between wetlands and hibernacula for the conservation of wetlands herpetofauna.     

The effects of deletions of the mouse Y chromosome long arm on sperm function--intracytoplasmic sperm injection (ICSI)-based analysis

In mouse and man, Y chromosome deletions are frequently associated with spermatogenic defects. XY(Tdy)(m1)qdelSry males have an extensive Yq deletion that almost completely abolishes the expression of two gene families, Ssty and Sly, located within the male-specific region of the mouse Y long arm. These males exhibit severe sperm defects and sterility. XY(RIII)qdel males have a smaller interstitial Yq deletion, removing approximately two thirds of Ssty/Sly gene copies, and display an increased incidence of mild sperm head anomalies with impairment of fertility and an intriguing distortion in the sex ratio of offspring in favor of females. Here we used intracytoplasmic sperm injection (ICSI) to investigate the functional capacity of sperm from these Yq deletion males. Any selection related to the ability of sperm to fertilize in vitro is removed by ICSI, and we obtained two generations of live offspring from the infertile males. Genotyping of ICSI-derived offspring revealed that the Y(Tdym1)qdel deletion does not interfere with production of Y chromosome-bearing gametes, as judged from the frequency of Y chromosome transmission to the offspring. ICSI results for XY(RIII)qdel males also indicate that there is no deficiency of Y sperm production in this genotype, although the data show an excess of females following in vitro fertilization and natural mating. Our findings suggest that 1) Yq deletions in mice do not bias the primary sex ratio and 2) Y(RIII)qdel spermatozoa have poorer fertilizing ability than their X-bearing counterparts. Thus, a normal complement of the Ssty and/or Sly gene families on mouse Yq appears necessary for normal sperm function. Summary: ICSI was successfully used to reproduce infertile mice with Yq deletions, and the analysis of sperm function in obtained offspring demonstrated that gene families located within the deletion interval are necessary for normal sperm function.