Cold-adapted Populations Research Articles

Comparative morphometrics of the primate apical tuft

The relationship between the structure and function of the primate apical tuft is poorly understood. This study addresses several hypotheses about apical tuft morphology using a large modern primate comparative sample. Two indices of tuft size are employed: expansion and robusticity. First, comparisons of relative apical tuft size were drawn among extant nonhuman primate groups in terms of locomotion and phylogenetic category. Both of these factors appear to play a role in apical tuft size among nonhuman primates. Suspensory primates and all platyrrhines had the smallest apical tufts, while terrestrial quadrupeds and all strepsirrhines (regardless of locomotor category) had the largest tufts. Similarly, hypotheses regarding the apical tufts of hominins, especially the large tufts of Neandertals were addressed using a comparison of modern warm- and cold-adapted humans. The results showed that cold-adapted populations possessed smaller apical tufts than did warm-adapted groups. Therefore, the cold-adaptation hypothesis for Neandertal distal phalangeal morphology is not supported. Also, early modern and Early Upper Paleolithic humans had apical tufts that were significantly less expanded and less robust than those of Neandertals. The hypothesis that a large apical tuft serves as support for an expanded digital pulp is supported by radiographic analysis of modern humans in that a significant correlation was discovered between the width of the apical tuft and the width of the pulp. The implications of these findings for hypotheses about the association of apical tuft size and tool making in the hominin fossil record are discussed.

Thermal evolution of pre-adult life history traits, geometric size and shape, and developmental stability in Drosophila subobscura

Replicated lines of Drosophila subobscura originating from a large outbred stock collected at the estimated Chilean epicentre (Puerto Montt) of the original New World invasion were allowed to evolve under controlled conditions of larval crowding for 3.5 years at three temperature levels (13, 18 and 22 degrees C). Several pre-adult life history traits (development time, survival and competitive ability), adult life history related traits (wing size, wing shape and wing-aspect ratio), and wing size and shape asymmetries were measured at the three temperatures. Cold-adapted (13 degrees C) populations evolved longer development times and showed lower survival at the highest developmental temperature. No divergence for wing size was detected following adaptation to temperature extremes (13 and 22 degrees C), in agreement with earlier observations, but wing shape changes were obvious as a result of both thermal adaptation and development at different temperatures. However, the evolutionary trends observed for the wing-aspect ratio were inconsistent with an adaptive hypothesis. There was some indication that wing shape asymmetry has evolutionarily increased in warm-adapted populations, which suggests that there is additive genetic variation for fluctuating asymmetry and that it can evolve under rapid environmental changes caused by thermal stress. Overall, our results cast strong doubts on the hypothesis that body size itself is the target of selection, and suggest that pre-adult life history traits are more closely related to thermal adaptation.

Body size, body proportions, and encephalization in a Middle Pleistocene archaic human from northern China.

The unusual discovery of associated cranial and postcranial elements from a single Middle Pleistocene fossil human allows us to calculate body proportions and relative cranial capacity (encephalization quotient) for that individual rather than rely on estimates based on sample means from unassociated specimens. The individual analyzed here (Jinniushan) from northeastern China at 260,000 years ago is the largest female specimen yet known in the human fossil record and has body proportions (body height relative to body breadth and relative limb length) typical of cold-adapted populations elsewhere in the world. Her encephalization quotient of 4.15 is similar to estimates for late Middle Pleistocene humans that are based on mean body size and mean brain size from unassociated specimens.

Ecotypic Differentiation in Thermal Traits in the Tropical to Warm-Temperate Green Macrophyte Valonia utricularis

Differentiation of thermal traits (i.e. growth, survival and reproduction) was studied in the green macrophyte Valonia utricularis (Roth) C. Agardh, which has a world-wide tropical to warm-temperate distribution. Ecotypic differentiation between northeast Atlantic/Mediterranean and Indo-west Pacific isolates occurred with respect to all investigated temperature characteristics. The Atlantic/Mediterranean group is more eurythermal and cold-tolerant compared to the Indo-west Pacific group, which is stenothermal and cold-sensitive. Isolates of Atlantic/Mediterranean origin show clearly higher growth rates at low temperatures (lower temperature limit: 5-8 vs. 18-20degreesC) and a much better tolerance to low temperatures than the Indo-west Pacific isolates (0-5 vs. 16degreesC). Large shifts towards low temperatures are accompanied by parallel but smaller shifts at high temperatures. Differences in upper survival temperatures amounted on average to 4degreesC (32-33degreesC vs. 34-37degreesC) and growth ceased in the Atlantic isolates at 30degreesC, whereas the Indo-west Pacific isolates still reached significant growth at 33degreesC. Additionally, temperature requirements for reproduction were shifted towards lower temperatures in the Atlantic/Mediterranean isolates [18-20 and 25degreesC vs. 28-30(33)degreesC]. The, cold-adapted Atlantic/Mediterranean ecotype retained a strong tropical imprint with high temperature tolerance and high growth rates at temperatures > 25degreesC. The northern distribution limit in the northeastern Atlantic Ocean at 39degreesN (at the 13degreesC February and 17degreesC August isotherms) is probably set by a growth and/or reproduction boundary. The northern distribution limit in the Pacific Ocean at 26degreesN (at the 21degreesC February and 29degreesC August isotherms) is probably set by low lethal winter temperatures. The different latitudes of these boundaries must be attributed to the occurrence of more cold-adapted populations in the northeastern Atlantic Ocean compared to the northwestern Pacific Ocean. The development of cold-adaptation in the northeastern Atlantic Ocean and its absence in the northwestern Pacific Ocean has been related to different impacts of Pleistocene glaciations.

Prevalence of alkane monooxygenase genes in Arctic and Antarctic hydrocarbon-contaminated and pristine soils1

Abstract The prevalence of four alkane monooxygenase genotypes (Pseudomonas putida GPo1, Pp alkB; Rhodococcus sp. strain Q15, Rh alkB1 and Rh alkB2; and Acinetobacter sp. strain ADP-1, Ac alkM) in hydrocarbon-contaminated and pristine soils from the Arctic and Antarctica were determined by both culture-independent (PCR hybridization analyses) and culture-dependent (colony hybridization analyses) molecular methods, using oligonucleotide primers and DNA probes specific for each of the alk genotypes. PCR hybridization of total soil community DNA detected the rhodococcal alkB genotypes in most of the contaminated (Rh alkB1, 18/20 soils; Rh alkB2, 13/20) and many pristine soils (Rh alkB1, 9/10 soils; Rh alkB2, 7/10), while Pp alkB was generally detected in the contaminated soils (15/20) but less often in pristine soils (5/10). Ac alkM was rarely detected in the soils (1/30). The colony hybridization technique was used to determine the prevalence of each of the alk genes and determine their relative abundance in culturable cold-adapted (5 degrees C) and mesophilic populations (37 degrees C) from eight of the polar soils. The cold-adapted populations, in general, possessed relatively higher percentages of the Rh alkB genotypes (Rh alkB1, 1.9% (0.55); Rh alkB2, 2.47% (0.89)), followed by the Pp alkB (1.13% (0.50)), and then the Ac alkM (0.53% (0.36)). The Rh alkB1 genotype was clearly more prevalent in culturable cold-adapted bacteria (1.9% (0.55)) than in culturable mesophiles (0.41 (0.55)), suggesting that cold-adapted bacteria are the predominant organisms possessing this genotype. Overall, these results indicated that (i) Acinetobacter spp. are not predominant members of polar alkane degradative microbial communities, (ii) Pseudomonas spp. may become enriched in polar soils following contamination events, and (iii) Rhodococcus spp. may be the predominant alkane-degradative bacteria in both pristine and contaminated polar soils.

Prevalence of alkane monooxygenase genes in Arctic and Antarctic hydrocarbon-contaminated and pristine soils

The prevalence of four alkane monooxygenase genotypes ( Pseudomonas putida GPo1, Pp alkB; Rhodococcus sp. strain Q15, Rh alkB1 and Rh alkB2; and Acinetobacter sp. strain ADP-1, Ac alkM) in hydrocarbon-contaminated and pristine soils from the Arctic and Antarctica were determined by both culture-independent (PCR hybridization analyses) and culture-dependent (colony hybridization analyses) molecular methods, using oligonucleotide primers and DNA probes specific for each of the alk genotypes. PCR hybridization of total soil community DNA detected the rhodococcal alkB genotypes in most of the contaminated (Rh alkB1, 18/20 soils; Rh alkB2, 13/20) and many pristine soils (Rh alkB1, 9/10 soils; Rh alkB2, 7/10), while Pp alkB was generally detected in the contaminated soils (15/20) but less often in pristine soils (5/10). Ac alkM was rarely detected in the soils (1/30). The colony hybridization technique was used to determine the prevalence of each of the alk genes and determine their relative abundance in culturable cold-adapted (5°C) and mesophilic populations (37°C) from eight of the polar soils. The cold-adapted populations, in general, possessed relatively higher percentages of the Rh alkB genotypes (Rh alkB1, 1.9% (0.55); Rh alkB2, 2.47% (0.89)), followed by the Pp alkB (1.13% (0.50)), and then the Ac alkM (0.53% (0.36)). The Rh alkB1 genotype was clearly more prevalent in culturable cold-adapted bacteria (1.9% (0.55)) than in culturable mesophiles (0.41 (0.55)), suggesting that cold-adapted bacteria are the predominant organisms possessing this genotype. Overall, these results indicated that (i) Acinetobacter spp. are not predominant members of polar alkane degradative microbial communities, (ii) Pseudomonas spp. may become enriched in polar soils following contamination events, and (iii) Rhodococcus spp. may be the predominant alkane-degradative bacteria in both pristine and contaminated polar soils.

Response of cold-adapted microbial populations in a permafrost profile to hydrocarbon contaminants

AbstractHeterotrophic and hydrocarbon-degrading microbial populations in soils from different depths in a permafrost soil profile at a hydrocarbon-contaminated site at Ny-Ålesund, Svalbard, were examined and compared to the populations present at a pristine site. The objective was to investigate whether the populations were enhanced after 12 years of exposure to hydrocarbons. Based on air and soil temperature data, it is concluded that the microorganisms living in these environments are cold-adapted. Proliferation of the populations by a factor of 100–1000 was measured in the layers where mineral oil was present in high concentrations. This indicates that the populations responded to the additional carbon source by degradation and growth on hydrocarbons or hydrocarbon metabolites. A high number of intrinsic heterotrophic and hydrocarbon-degrading bacteria is a prerequisite forin situbioremediation of contaminated sites. Although the hydrocarbon-degrading activities of the populations are not known, the results show that the population sizes probably do not represent the limiting factor in a bioremedial action at this contaminated Arctic permafrost site.

Determination of the origin of the cold-adapted populations of barnyard grass (Echinochloa crus-galli) in eastern North America: a total-evidence approach using RAPD DNA and DNA sequences

This survey attempts to establish the origin of cold-adapted populations of barnyard grass (Echinochloa crus-galli (L.) Beauv.) in North America using molecular techniques, including random amplified polymorphic DNA (RAPD) and two types of sequences: chloroplast intron (trnL (UAA)) and rDNA nuclear spacer (ITS 1). There exists many possible scenarios to explain the origin of E. crus-galli in eastern Canada (Quebec), but we dwelled on two particular hypotheses, which are not mutually exclusive. The first hypothesis stipulates that the populations originated only from Europe, whereas the second implies that native subtropical and warm-temperate populations migrated from the south towards northern regions. To assess the likelihood of these hypotheses, the genetic distance matrices obtained from RAPD markers, nuclear, and chloroplastic sequences were combined and tested against the competing models. A principal coordinate analysis was used to discriminate among populations sampled from three different regions (i.e., Quebec, American east coast, and western Europe) and an analysis of molecular variance (AMOVA) detected a significant genetic structure among these populations (FST= 0.110, p < 0.05). Pairwise comparisons further indicated that European populations were significantly different from all other populations, whereas North American populations were not different from one another. The combined sequences revealed eight different haplotypes. Six populations were characterized by unique haplotypes, while one haplotype was shared by 3 of the 12 North American populations. The last and most common haplotype was observed in 9 of the 18 populations from all three regions. The tests computed thus supported the second hypothesis suggesting that the cold-adapted populations of eastern Canada are probably derived from other North American populations rather than European populations.Key words: AMOVA, RAPD, rDNA, cpDNA, genetic variation, population structure.

Determination of the origin of the cold-adapted populations of barnyard grass (<i>Echinochloa crus-galli</i>) in eastern North America: a total-evidence approach using RAPD DNA and DNA sequences

This survey attempts to establish the origin of cold-adapted populations of barnyard grass (Echinochloa crus-galli (L.) Beauv.) in North America using molecular techniques, including random amplified polymorphic DNA (RAPD) and two types of sequences: chloroplast intron (trnL (UAA)) and rDNA nuclear spacer (ITS 1). There exists many possible scenarios to explain the origin of E. crus-galli in eastern Canada (Quebec), but we dwelled on two particular hypotheses, which are not mutually exclusive. The first hypothesis stipulates that the populations originated only from Europe, whereas the second implies that native subtropical and warm-temperate populations migrated from the south towards northern regions. To assess the likelihood of these hypotheses, the genetic distance matrices obtained from RAPD markers, nuclear, and chloroplastic sequences were combined and tested against the competing models. A principal coordinate analysis was used to discriminate among populations sampled from three different regions...

Temperature responses of tropical to warm-temperate Atlantic seaweeds. II. Evidence for ecotypic differentiation in amphi-Atlantic tropical-Mediterranean species

Nineteen isolates of four amphi-Atlantic seaweed species with a tropical to warm-temperate/Mediterranean distribution (Microdictyon boergesenii, M. tenuis, Wurdemannia miniata and Valonia utricularis) and one eastern Atlantic endemic (M. calodictyon) have been investigated for their temperature responses (tolerance limits and growth response curves). In all species, isolates survived undamaged at 30°C but died at 33 or 35°C. Growth occurred up to 30°C in most isolates but no growth was observed at higher (33°C) temperatures. Tolerance to low temperatures showed marked differences between and within species. In tropical isolates, damage generally occurred between 15 and 18°C and plants grew at temperatures down to 18–20°C. Isolates from warm-temperature localities (Canary Islands and Mediterranean) tolerated much lower temperatures (0–12°C), and showed substantial growth at temperatures as low as 15–18°C, which indicates ecotypic differentiation. It is hypothesized that these cold-adapted populations are descendants of populations which were isolated in the eastern Mediterranean during the last glacial episode and recolonized the western Mediterranean and Canary Islands at the onset of the interglacial.

A model explaining patterns of geographic character variation inCordyius cordylus(Reptilia; Cordylidae) in the south-western Cape, South Africa

A model is proposed for the evolution of three morphotypes of the girdled lizard Cordylus cordylus (Linnaeus) in the south-western Cape. The available data are interpreted as indicating that a vicariant splitting of a warm-adapted ancestral population during the last glacial period occurred. Differential evolution of the two daughter populations in response to different environmental pressures resulted. One of the daughter populations remaining in the coastal lowlands to the west of the Cape Fold Mountains, became cold-adapted, an event which was followed by a rapid range expansion. The other daughter population to the south and east of the Cape Fold Mountains apparently experienced less severe climatic conditions, maintained a larger population size, and for these reasons remained warm-adapted. During the subsequent warmer, interglacial period the now cold-adapted daughter population was again fragmented into two populations. Of these, one is presently found along the south-western coast and the other along the higher peaks of the western section of the Cape Fold Mountains. On the other hand the amelioration of the climate during the interglacial allowed the warm-adapted daughter population to the south and east to expand its range, eventually penetrating into the areas formerly occupied by the cold-adapted populations. Subsequently zones of secondary contact were established. In the area under discussion similar patterns of contraction and expansion can be observed in other closely related species. Our data support the turnover-pulse hypothesis of Vrba (1985).

The Living Races of Man by Carleton S. Coon, with Edward E. Hunt, Jr. (review)

traditions are not spared, nor is their present fivefold preeminence in lists ofsubversives. Weyl's study ofsurnames is carried a novel step further, proving within a nationality wide differences ofrank among its names—especially among theJews whose surnames are ofrecent origin. Levine, Epstein, Stern, Shapiro, and Kaplan outrank by nine to four in descending order such names as Cohen in twenty rosters of eminence. The explanation is to be found in the learned rank of the original bearers. So the English names Clark, Palmer, Draper, and Miner outrank other English names for similar reasons, and the Clarkes are a bit better than the Clarks, while the Puritan names from southern New England far outrank the common English names, as Huntington had shown. A fine book, crammed with novel and well-proved data on all the races and kiths in our country. S. Colum Gilfillan, Ph.D. I2i¡ Ocean Avenue Santa Monica, California 90401 The Living Races ofMan. By Carleton S. Coon, with Edward E. Hunt,Jr. New York: Knopf, 1965. Pp. xxxii+344+xx. $10.00. Carleton Coon is a great anthropologist because he has recognized fundamental problems ofhis subject and has given fresh and reasoned insights into them. These problems are: (1) How did the modem races ofman evolve in the Pleistocene? (2) What adaptive significance is there in the differences among human races? The first ofthese was scarcely even noted before his recent book, The Origin ofRaces fi], and the publication in 1950 of Races by Coon, Garn, and Birdsell [2] was a milestone in the study of the second. The Living Races ofMan is devoted to a description of the major physical differences among the peoples ofthe world and to an analysis of the possible causes ofthese differences . Somewhat over one-half the book concerns the traits, environments, languages, implements, and history (up to the present) ofthe various human groups, all integrated in a geographical framework. Numerous maps and about two hundred photographs of individuals of different groups add clarity. I am a geneticist and paleontologist, not an anthropologist, and can only say that I found this part ofthe book (and the rest) well and interestingly written. The literature on human diversity is cluttered with middens of observations that are seldom made part ofan intelligible picture. A major simplification advocated by Coon is the importance of what he calls "Movius' Line," for its discoverer, stretching west of Sinkiang and south of Tibet to the Bay of Bengal. The Mongoloids and Australoids evolved east of this line for hundreds ofthousands ofyears, according to Coon, and the other races west ofit. He postulates less interchange across the line than among the groups on either side. In particular, he hypothesizes that the Negroes have a relatively large amount ofCaucasoid ancestry and that their origin as a group may be due to this admixture (original or secondary) with the forest pygmies. This and other original hypotheses will undoubtedly stir the air and perhaps a few minds for some time. It is obvious that different human populations differ in the frequencies ofmany traits. 320 Book Reviews Perspectives in Biology and Medicine · Winter 1967 But why do they differ? How important relative to each other are the antipodal forces ofadaptation andhistorical accident? Coon sets himselfsquarely in the camp ofadaptation and (with Hunt involved in this part) presents an impressive amount ofdirect and indirect evidence for an adaptive significance ofa wide variety oftrends. The aspects ofthe environment invoked are mainly epidemic diseases and climate, and the geography of different aspects ofclimate itselfoccupies fifteen pages with maps. Some ofthe characters discussed are relatively recondite, and for some no adaptive significance is suggested. It is peculiar, although not physiologically inexplicable, that both increased heat flow through the lower arms (some Mongoloids) and decreased flow (cold-adapted populations of other races) are regarded by workers in the area as specific adaptations to cold. Coon does not, I think, mention chance as even a real alternative to selection (including pleiotropic adaptation). However, human populations have often been small, and realistic models now indicate that random elements may have been moderately important in human evolution for monogenic or even oligogenic traits. The general importance of these random elements is...