Genetic studies of the Macushi and Wapishana Indians

Summary Blood samples from 509 Macushi and 623 Wapishana Amerindians of Northern Brazil and Southern Guyana have been analyzed with reference to the occurrence of rare variants and genetic polymorphisms of the following 25 systems: (i) Erythrocyte enzymes: acid phosphatase-1, adenosine deaminase, adenylate kinase-k, carbonic anhydrase-1, carbonic anhydrase-2, esterase A_1,2,3, esterase D, galactose-1-phosphate uridyltransferase, isocitrate dehydrogenase, lactate dehydrogenase, malate dehydrogenase, nucleoside phosphorylase, peptidase A, peptidase B, phosphoglucomutase 1, phosphoglucomutase 2, phosphogluconate dehydrogenase, phosphohexoseisomerase, triosephosphate isomerase and (ii) Serum proteins: albumin, ceruloplasmin, haptoglobin, hemoglobin A, hemoglobin A₂ and transferrin. Fifteen different rare variants were detected, involving 11 of these systems. In addition, a previously undescribed variant of ESA_1,2,3 which achieves polymorphic proportions in both these tribes is described. Excluding this variant, the frequency of rare variants is 1.1/1000 in 12510 determinations in the Macushi and 4.7/1000 in 15 396 determinations in the Wapishana. The ESA_1,2,3, polymorphism was not observed in 382 Makiritare, 232 Yanomama, 146 Piaroa, 404 Cayapo, 190 Kraho and 112 Moro. Irregularities in the intratribal distribution of this polymorphism in the Macushi and Wapishana render a decision as to the tribe of origin impossible at present. Gene frequencies are also given for previosly described polymorphisms of 5 systems: haptoglobin, phosphoglucomutase 1, erythrocyte acid phosphatase, esterase D, and galactose-1-phosphate-uridyl-transferase.Research supported by the National Science Foundation and the Energy Research and Development Administration.     

The genetic structure of a tribal population, the Yanomama Indians XI. Gene frequencies for 10 blood groups and the ABH-Le secretor traits in the Yanomama and their neighbors; the uniqueness of the tribe.

In this paper we present the results of blood group typings for a total of 33 villages distributed among five South American Indian tribes--Yanomama (21 villages), Makiritare (eight villages), Macushi (two villages), Piaroa (one village), and Wapishana (one village). These new results for the Yanomama and Makiritare tribes have been combined with those previously reported to allow a better appreciation of the distribution of allelic frequencies in the tribes. The relationship of the Yanomama to other South American Indian tribes is investigated using data on six polymorphic loci (Rh, MNS, Fy, Jk, Di, Hp). By use of four genetic measures (two of genetic relationship and two of genetic diversity), we demonstrate that the Yanomama are genetically unique among a sample of 20 South American tribes. In addition, the Yanomama show somewhat less genetic diversity for the six loci analyzed than the average South American tribe. Taken together, these results indicate a rather long period of isolation for the population antecedent to the Yanomama--perhaps since the time of entry of man into the South American continent. The pattern of genetic relationships and genetic diversity for the 20 tribes is consistent with the hypothesis that evolution in South America proceeded by a process of fission-fusion leading to isolation of subpopulations with subsequent genetic differentiation as a consequence of population isolation. The uniqueness of the Yanomama appears to stem entirely from such a process, there being no evidence of any selective differential for the loci analyzed.     

The PiGMaP consortium linkage map of the pig (Sus scrofa)

A linkage map of the porcine genome has been developed by segregation analysis of 239 genetic markers. Eighty-one of these markers correspond to known genes. Linkage groups have been assigned to all 18 autosomes plus the X Chromosome (Chr). As 69 of the markers on the linkage map have also been mapped physically (by others), there is significant integration of linkage and physical map data. Six informative markers failed to show linkage to these maps. As in other species, the genetic map of the heterogametic sex (male) was significantly shorter (16.5 Morgans) than the genetic map of the homogametic sex (female) (21.5 Morgans). The sex-averaged genetic map of the pig was estimated to be 18 Morgans in length. Mapping information for 61 Type I loci (genes) enhances the contribution of the pig gene map to comparative gene mapping. Because the linkage map incorporates both highly polymorphic Type II loci, predominantly microsatellites, and Type I loci, it will be useful both for large experiments to map quantitative trait loci and for the subsequent isolation of trait genes following a comparative and candidate gene approach.     

The NGF complex from the African ratMastomys natalensis

The 7S NGF complex from the male mouse submaxillary gland consists of the , and subunits in the ratio ₂₂. The (NGF) subunit contains all the known biolocial activity of 7S NGF. The and subunits are both members of glandular kallikrein gene family, yet only subunit has protease activity. The subunit plays a role in the processing of preproNGF to its mature form, while the role of the subunit is not yet understood. Despite the fact that 7S NGF has been extensively characterized, no other NGF complex has been characterized, nor have the or subunits been observed in tissues which express NGF. We have therefore purified and characterized the NGF complex from the submaxillary glands of the ratMastomys natalensis in order to more fully understand the roles of the and subunits. The NGF complex from M. natalensis contains subunits similar to those found in mouse 7S NGF. Although similar, there are significant differences between mouse and M. natalensis NGF complexes, especially in the degree of post-translational modification of the and NGF subunits, the expression of esterase activity and the ease with which the complexes dissociate. Evidence is presented that suggests that the NGF complex from M. natalensis may consist of subunits in the ratio ₂. The amino acid sequence of the M. natalensis NGF suggests some, but not all, ways in which these differences arise.Special issue dedicated to Dr. Lawrence Austin     

Isoenzyme status and genetic variability of serum esterases in the lesser snow goose,Anser caerulescens caerulescens

A maximum of 22 bands comprising four esterase subgroups—acetylesterase, carboxylesterase, cholinesterase, and acetylcholinesterase—were detected following electrophoresis of lesser snow goose sera on polyacrylamide gels. A minimum of seven structural genes was surmised to be involved in the biosynthesis of these enzymes following physiochemical characterizations. The genetic variability of these loci was calculated to be 1.25% average heterozygosity, while 14.3% of the loci were polymorphic. These estimates of genetic variability were substantially lower than those reported for other vertebrate species. The low degree of genetic variability found in snow goose serum esterases coupled with the extensive protein multiplicity observed may possibly reflect an adaptive strategy based on biochemical plasticity rather than genic heterozygosity for this species. The nature of evolutionary forces acting upon multiple enzyme systems such as esterases is discussed. The concept of conditional neutrality is introduced and defined within this context.This research was carried out under grants from the National Research Council of Canada and the Canadian Wildlife Service to F. Cooke. J. Grossfield was supported by grants from the National Institutes of Health, GM 21630 and FRAP 10576.     

Simultaneous overproduction of extracellular endoglucanase and intracellular β-glucosidase by genetically engineered Bacillus subtilis

Summary Simultaneous overproduction of intracellular -glucosidase and extracellular endoglucanase was attempted by constructing two artificial operon systems comprising the -glucosidase-endoglucanase gene(E) or the endoglucanase--glucosidase gene(E) under the control of a strong engineered promoter, BJ27U88 and expressing them in Bacillus subtilis DB104. Two artificial operon systems contained 30 bp or 5 bp gap between the termination codon of the upstream gene and the SD sequence of the downstream gene, respectively. These operon systems were expressed well in B. subtilis and overproduced the -glucosidase cell extract as well as the endoglucanase supernatant. The level of expression in the operon system was almost the same as that in a single expression system.     

Concluding remarks

On the basis of symposium contributions onChlorella, Hibbertia, Eucalyptus, Ambrosia and on numerical approaches some fundamental problems of (bio)systematics, evolution, and taxonomic categories are discussed: Methods available for analysing affinities; conflicting evidence from phenetic, biochemical, cytogenetic and other analyses; further classification problems in cases of intermediacy, etc. While sibs of various levels and their natural hierarchy often can be objectively defined, this appears impossible for particular taxonomic levels itself (e. g. species). A single objective taxonomic system of organisms is unrealistic. Certain guiding lines for relative and practicable concepts of species and genus are proposed.Presented at the symposium Speciation and the Species Concept during the XIIth International Botanical Congress, Leningrad, July 8, 1975.     

The frequency of the γ chain variant AγT in different populations,and its use in evaluating γ gene expression in association with thalassemia

Summary The occurrence of the ^AT chain (i.e. ^A75 Ile Thr) in different populations was evaluated through a study of 4250 cord blood samples and blood samples from more than 350 SS¹ patients. High frequencies were observed in Italy, Yugoslavia, Turkey, Holland, but also in Japan, Vietnam, and India. The chain is (nearly) absent in the Black population of Ghana and Kenya, and low frequencies were observed in China and Australian aborigines. Only a few adult SS patients (18 out of 357) were ^AT heterozygotes. The chromosomes with the ^AT globin gene were mapped through an evaluation of the presence of 10 different restriction sites. The ^AT chromosomes from different populations were closely related and had the same subhaplotypes of [--++-+] (Hinc II 5 to ; Xmn I 5 to ^G; Hind III in ^G and ^A; Hinc II in and 3 to ), quite different from the subhaplotypes seen for ^AT negative chromosomes.² This suggests a common ancestor which may have originated in Southern Europe. An evaluation of the chain production by both chromosomes in SS patients and -thalassemia heterozygotes was possible for subjects with an ^AT heterozygosity. It was concluded that in -thalassemia trait, the chain synthesis is directed for about two-thirds by the thalassemic chromosome and for about onethird by the normal chromosome; the contribution by the normal chromosome decreases with a decrease in total chain production.This is contribution #0890 of the Department of Cell and Molecular Biology, Medical College of Georgia, Augusta, GA 30912, USA     

Histochemical study of enzyme patterns in the human submaxillary gland

Summary The histochemical distribution of various enzymes, such as alkaline phosphatase, acid phosphatase, esterase, -glycosidase, aminopeptidase, succinic dehydrogenese and TPN diaphorase, in human submaxillary glands has been determined.Acini and ducts of human submaxillary gland were devoid of alkaline phosphatase activity, but this enzyme was observed in capillaries and somewhat in myoepithelium.Activities of acid phosphatase, esterase, -glucuronidase and -galactosidase were generally observed in the entire cytoplasm of serous acini; but the cytoplasm of mucous acini was either negative or showed only trace amounts.Aminopeptidase reaction of both acini and ducts was generally negative.Succinic dehydrogenase and TPN diaphorase activities were strongly active in intralobuler ducts. Serous acini exhibited less activity with these enzymes; and mucous cells showed still less and were almost negative. In serous acini, there was much greater activity of TPN diaphorase than of succinic dehydrogenase.With 7 Figures in the Text     

Bias in genetic variance estimates due to spatial autocorrelation

Summary A central problem in the analysis of genetic field trials is the dichotomy of genetic and environmental effects because one cannot be defined without the other. Results from 768,000 simulated family trials in complete randomized block designs demonstrated a serious upward bias in estimates of family variance components from multi-unit plot designs when the phenotypic observations were compatible with a first-order autoregressive (AR1) process. The inflation of family variances and, thus, additive genetic variance and narrow sense individual heritabilities progressed exponentially with an increase in the nearest neighbor correlation () in the AR1 process. Significant differences in inflation rates persisted among various plot configurations. At = 0.2 the inflation of family variances reached 48–73%. Inflation rates were independent of the level of heritability. Modified Papadakis nearest neighbor (NN) adjustment procedures were tested for their ability to remove the bias in family variances. A NN-adjustment based on Mead's coefficient of interplant interaction and one derived from Bartlett's simultaneous autoregressive scheme removed up to 97% of the bias introduced by the phenotypic correlations. NN-adjusted estimates had slightly (5–8%) higher relative errors than did unadjusted estimates.     

The adaptive significance of cultural behavior: Comments and reply

Summary Fundamentally, theoretically, there is only one process underlying genetic and cultural evolution: natural selection. Organism fitness-enhancement (adaptive significance) is one of its practical mechanisms; group formation and maintenance is another, often but not always through fitness-enhancement; and need-fulfillment is still another. If Durham can accept that formulation, and switch from organism-thinking to instruction-thinking (Cloak, 1975: 178), he will free himself from two handicaps: First, he can forget his worries about reductionism and determinism (1976a: 100, 101). Under this general theory of natural selection, cultural evolutionis biological evolution, continued by other (nongenetic) means. Second, he will spare himself the appearance of anthropomorphism, mentalism, and wishy-washiness attendant on his discussion of kinds of significance, other than adaptive significance, of cultural behaviors (1976a: 102–106, 115).     

The North Sea: source or sink for nitrogen and phosphorus to the Atlantic Ocean?

Annual nitrogen and phosphorus budgets for the whole North Sea taking into account the most recent data available were established. The area considered has a total surface of approximately 700,000km² and corresponds to the definition by OSPARCOM (Oslo and Paris Commission) with the exclusion of the Skagerrak and Kattegat areas. Input and output fluxes were determined at the marine, atmospheric, sediment and continental boundaries, and riverine inputs based on river flows and nutrient concentrations at the river–estuary interface were corrected for possible estuarine retention. The results showed that the North Sea is an extremely complex system subjected to large inter-annual variability of marine water circulation and freshwater land run-off. Consequently, resulting total N (TN) and P (TP) fluxes are extremely variable from 1 year to another and this has an important influence on the budget of these elements. Total inputs to the North Sea are 8870±4860kTNyear^–1 and 494±279kTPyear^–1. Denitrification is responsible for the loss of 23±7% of the TN inputs while sediment burial is responsible for the retention of only of 2±2% of the TP input. For TN, due to the large variability on marine and estuarine fluxes, and to the uncertainty related to the denitrification rate, it was concluded that the North Sea could either be a source (1930kTNyear^–1) or a sink (1700kTNyear^–1) for the waters of the North Atlantic Ocean. For TP it was concluded that the North Sea is mostly a source (–4 to 52kTPyear^–1) for the waters of the North Atlantic Ocean.     

Gene Flow Among Calomys Musculinus (Rodentia, Muridae) Populations in Argentina

Calomys musculinus is a Sigmodontinae rodent inhabiting periodically disturbed habitats in the central eastern plains of Argentina. It is the natural reservoir host of Junin virus, the etiological agent of Argentine Hemorrhagic Fever (AHF). In order to analyze the levels of gene flow among populations of this species, allozymic variability at 26 loci was studied in 291 individuals from the endemic zone of AHF and localities outside it. All populations showed high levels of polymorphism (H _e between 0.107 and 0.144; P_95% between 38 and 54%). Individual loci f values were in most cases negative, although not significantly different from zero. Mean genetic differentiation among populations was low, but statistically significant (=0.020; P<0.01). There was no correlation between genetic and geographic distances between pairs of populations, and scatter of the pairwise points suggests that, at the regional scale, genetic drift is more influential than gene flow. This result can be interpreted as indicative of a relatively recent expansion of C. musculinus habitat and restricted on-going gene flow, which would be compatible with a relatively slow expansion rate of AHF.     

Sequence analysis of a small early chorion gene subfamily interspersed within the late gene locus in Bombyx mori

A comprehensive sequence analysis of three early chorion genes (6F6.1, 6F6.2, 6F6.3) which form a small subfamily is presented. Two main features characterize this subfamily: (1) the 6F6 gene copies are -branch genes and, unlike typical chorion genes which are organized in divergent gene pairs, they are unpaired, and (2) they are not clustered in genetic locus Ch3 but are dispersed in Ch1-2, which is about 3 to 4 centiMorgans away and contains middle and late chorion genes. Sequence comparisons show that members of this subfamily exhibit high identity values in their major coding region (94–96%) and that similarities also extend, but to a lesser degree, into their noncoding regions. The putative 6F6 promoter regions have no significant similarities with the corresponding regions of other early -genes but quite surprisingly share common elements with middle and late genes. The main difference among the 6F6 gene introns is the presence of inserted sequences: the insert into 6F6.2 (IR; 248 bp) is flanked by a 102–103-bp inverted repeat, while those into 6F6.1 (FIB; 184 bp) and 6F6.3 (HOPE; 951 bp) are carried by a partial Bm1 element. HOPE has features of a non-LTR retrotransposable element. Preliminary experiments indicate that the copy number of IR and HOPE in the Bombyx mori genome is about 5,000 and 20,000, respectively. The great similarity of 6F6 genes cannot be accounted for by selective pressure but rather appears to be the result of gene-conversion-like events, which are supposed to operate frequently in middle and late chorion genes but not in other known early -genes. Using the relative position and orientation of the 6F6 gene copies, it is possible to propose an evolutionary scheme for the formation of chorion locus Ch1-2. Correspondence to: G.C. Rodakis     

Cystic kidneys

Summary According to the classification of Osathanondh and Potter of cystic kidneys we give an overview of the different types of cystic changes taking genetic aspects into account. Usually pathoanatomic types do not represent genetic entities: All type I kidneys are transmitted in an autosomal recessive way with varying clinical symptoms; in rare cases they even present in adults. The relationship to congenital hepatic fibrosis, cystic liver, and to the Caroli syndrome is discussed. Type II kidneys are usually not genetic in origin; but they may occur as part of several syndromes. Rarely genetic factors might contribute to type II kidneys that may present as familial cases of Potter syndrome (renal non-function syndrome). Type IV kidneys, although different in their pathoanatomic picture can be regarded according to a common pathogenetic theory as part of the spectrum of malformations as in type II. Therefore the genetic interpretation of type II kidneys also applies to type IV lesions. Type III kidneys include autosomal dominant polycystic kidney disease. This type may already present in childhood; the first prenatal diagnosis by ultrasonography is described in detail. Furthermore type III changes are part of syndromes or non-hereditary malformation complexes, and often present only as mild manifestations. Diseases with isolated involvement of the medulla (juvenile nephronophthisis/medullary cystic disease) or cortex are described as part of the differential diagnosis, they are heterogeneous and genetically only partly understood. Syndromes with cystic kidneys are reviewed as well as the possibilities of prenatal diagnosis of cystic diseases. Reliable prenatal diagnosis is only possible in type II, and possible in some of the other types. The nosology is improved if genetic information is taken into account.     

Clonal propagation of Callistemon by tissue culture techniques

Callus development in Callistemon viminalis was readily achieved when axillary buds derived from nodal tissue were placed in a medium containing macro- and micro-nutrients, sucrose (0.06 M), inositol (300 M), nicotinic acid (20 M), pyridoxine hydrochloride (3 M), thiamine hydrochloride (2 M), riboflavin (10 M), cytokinins (5 M) and auxins (0.1 M). The presence of benzylaminopurine (5 M) and p-chlorophenoxyacetic acid (0.1 M) promoted the most vigorous callus development and sprout formation. Rooting of nodal material was rare but occurred readily following the transference of sprouts developed on callus to a basal medium containing sucrose and salts. Root initiation was stimulated, however, by the presence of auxins. Chlorophenoxyacetic acid while stimulating root initiation repressed root growth. Indole butyric acid stimulated both root initiation and shoot growth at concentrations of 0.005 to 0.1 M. The treatment of choice for rooting and shoot growth was the addition of indole butyric acid at a concentration of 0.01 M.     

Relationship between measured chromosome distribution parameters and Ag-staining of the nucleolus organizer regions

Summary Trypsin-banded metaphase plates provided by one whole blood culture of a normal adult female were analyzed as to the chromosome distribution by measuring: (1) distances between centromeres; (2) angles formed between a centromere, the gravity center of the metaphase plane, and a second centromere; and (3) the measured tendency to associate, as defined by Galperin (1969b). These data are correlated with Ag-NOR staining findings obtained from 72 cells from another culture of the same individual. In these cells, the chromosome pairs are identified using a simultaneous Ag-NOR staining and acridine orange banding technique. The silver precipitation is also correlated with the scored satellite associations in these cells. The results show a correlation between all concerned parameters, indicating that the nucleolar function of the human acrocentric chromosomes, as demonstrated by the silver precipitation technique, is probably one of the major determinants of the proximity of these chromosomes. There is a pronounced correlation of the Ag-NOR findings with those measured parameters which describe best the preferential small distances between chromosomes (angle analysis and tendency to associated data). Moreover, the association patterns of the acrocentrics with small amounts of NOR provide some evidence for the interference of other determinants cogoverning the position of the human D-and G-group chromosomes.To whom offprint requests should be sent     

Die Feinstruktur der Zirbeldrüse normaler,trächtiger und experimentell beeinflußter Meerschweinchen

Zusammenfassung In der Meerschweinchenzirbeldrüse lassen sich elektronenmikroskopisch helle und dunkle Pinealzellen sowie einzelne Gliazellen nachweisen. In den bei weitem überwiegenden hellen Pinealzellen zeichnet sich ein Teil der vesicle-crowned rodlets (VCR) durch lokale Auftreibungen aus. Von VCR deutlich abzugrenzen sind die vesicle-crowned balls (VCB). Erstmalig beschrieben wird das Vorkommen von sog. Zylindern, die als Vorstufen von VCB aufgefaßt werden. In den relativ seltenen dunklen Pinealzellen, die sich durch chromatinreiche Kerne und elektronendichtes Zytoplasma auszeichnen, sind Vesikel, VCR, VCB und Zylinder seltener als in hellen Pinealzellen. Die reichlich vorhandenen marklosen Nervenfasern finden sich vor allem in perivasculären Räumen, seltener im Parenchym. Synapsen zwischen Nerven und Pinealzellen wurden nicht beobachtet. In den Zirbeldrüsen trächtiger Meerschweinchen zeichnen sich in der 2. Hälfte der Tragzeit die hellen Pinealzellen durch stärkere Lappung der Kerne, gehäuftes Auftreten von laktiven Zonen, Vermehrung von Mitochondrien, glattem ER, agranulären Vesikeln, VCR, VCB und Zylindern aus. Die dunklen Pinealzellen nehmen während der Tragzeit an Zahl zu. Post partum bilden sich diese Veränderungen innerhalb einer Woche zurück. Längerer Aufenthalt der Tiere in Dunkelheit führt zu einer Aktivierung der hellen Pinealzellen mit auffallender Vermehrung der VCR und zu einer Zunahme der dunklen Zellen. Unter Dauerbelichtung kommt es in den hellen Zellen zu einer Abnahme fast aller Zellorganellen und zu einer starken Vermehrung der VCR, die nach 70 Tagen auch Formveränderungen aufweisen. Nach Reserpinbehandlung beobachtet man eine Verminderung und degenerative Veränderungen der VCR. Es wird diskutiert, daß die VCR als prae- bzw. postsynaptische Strukturen der Erregungsübertragung von Nerven zu Pinealzellen bzw. von Pinealzellen untereinander dienen könnten.

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The fine structure of the pineal gland of normal, pregnant and experimentally affected guinea-pigs

Summary By means of electron microscopy light and dark pinealocytes can be distinguished in the guinea-pig pineal gland. Glial cells are rare. In the light pinealocyte. the most frequent cell type, some vesicle-crowned rodlets (VCR) show circumscribed thickenings. From these structures vesicle-crowned balls (VCB) have to be clearly distinguished. Furthermore cylinders occur, which, it is suggested, are precursors of VCB. Dark pinealocytes characterized by chromatin-rich nuclei and electron-dense cytoplasm are rare and contain fewer vesicles, VCR, VCB and cylinders than light pinealocytes. Numerous non-myelinated nerve fibres are situated within perivascular spaces, a few also in the parenchyma. Synapses between nerve fibres and pinealocytes were not observed. In the pineal gland of pregnant guinea-pigs the following changes can be observed in the second half of gestation. The light cells show many nuclear indentations and an increase of active zones, mitochondria, smooth ER, agranular vesicles, VCR, VCB, and cylinders respectively. The dark cells increase in number. After birth these changes reverse to normal within one week. Constant darkness leads to an activation of the light cells accompanied by an increase of the VCR and to an increase in number of the dark cells. Under constant illumination the light cells show a decrease of their organelles and a strong increase of the VCR. After 70 days the VCR also show a change in shape. Following reserpine treatment the VCR decrease in number and show signs of degeneration. It is discussed that the VCR function as pre- or postsynaptic structures and that they are involved either in transmitting impulses from nerve fibres to pinealocytes or from one pinealocyte to the other.

Untersuchung unter Leitung von Univ.-Doz. Dr. L. Vollrath.     

Conservation status of parrot populations in an Atlantic rainforest area of southeastern Brazil

A census of four species of syntopic parrots was carried out using distance sampling methods on São Sebastião island, SE Brazil. Most of the 33593 ha island is covered by mature and secondary Atlantic rainforest. Almost 80% of these forests are within the Ilhabela Park. Although the species counted have marked differences in size and weight, density (individuals/km²) and estimated population size in 23500 ha of well-preserved forests were similar: Amazona farinosa (13.82±5.94; 3247±1395), Pionus maximiliani (15.79±7.04; 3712±1654), Brotogeris tirica (15.05±4.87; 3537±1143) and Pyrrhura frontalis (13.06±5.53; 3068±1298). Encounter rates of Forpus crassirostris and Pionopsitta pileata were very low, which suggests that there is only a small population of these species on the island. The São Sebastião forests still support healthy populations of parrots. Although woodpecker population estimates on the island are large enough to provide nesting sites for parrots, competition for holes with other secondary cavity nesters such as toucans, flycatchers and tytiras, and the selective cutting of dead trees for canoe construction, which is a common practice on the island, may limit hole availability for parrots.