Range change in Metasequoia: relationship to palaeoclimate

Metasequoia was widely distributed across the mid and high latitudes of the Northern Hemisphere during the Cretaceous, and experienced range contraction associated with Tertiary climatic cooling and drying. We compile occurrences of Metasequoia from the literature, museum collections and new localities, and plot them in a plate tectonic framework to document these range changes through time. We note two pulses of range contraction: Eocene–Oligocene associated with cooling at high latitudes, and Late Miocene–Pliocene associated with cooling and drying in mid latitudes. Only the northern limit of the taxon's range changed during these intervals. Because of its apparent climate sensitivity, Metasequoia might be used to reconstruct palaeoclimate. To test this hypothesis, we assemble the climatic tolerances of living Metasequoia glyptostroboides under natural and cultivated conditions and compare them with palaeoclimate reconstructions across the genus' former range. The fossil record of Metasequoia shows that ancient members of the genus regenerated under similar conditions to those preferred by living M. glyptostroboides (mean annual temperature of 9–17 °C and mean annual precipitation of 953–2039 mm). However, some data suggest that early Tertiary representatives may have tolerated mean annual temperatures as high as 20–22 °C. Thus, the climate tolerance of Metasequoia appears to have evolved little since the Cretaceous, suggesting that it has potential as a palaeoclimate indicator when used in coordination with other climate proxies. However, Metasequoia alone cannot provide great precision.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 154 , 115–127.     

Seasonal changes in the numerical responses of predators to cyclic vole populations

Theoretical models predict that a delayed density-dependent mortality factor with a time lag of ca 9 months is able to drive 3–5-yr population cycles of northern voles. We studied numerical responses of predators in western Finland during 1986–92, in an area with 3-yr population cycles of voles. Abundances of small mammals were monitored in several farmland areas (each 3 km²) by snap-trapping in April, June, August, and October (only in 1986–90), and the abundances of avian, mammalian, and reptilian predators by visual censuses during trapping occasions. The 3-yr cycle studied was a cycle of Microtus voles (field vole M. agrestis and sibling vole M. rossiaemeridionalis ) and their small-sized predators (small mustelids and vole-eating birds of prey). The numerical responses of both migratory avian predators and small mustelids to changes in vole densities were more alike than different. In late summer (August), the time lag in the numerical response of all main predators was short (0–4 months), whereas longer time lags prevailed from spring to early summer. The length of the time lag in spring appeared to be related to the length of the winter, which indicates that strong seasonality may create longer time lags to the numerical response of predators at northern latitudes than at more southern latitudes. Our results suggest that, from spring to early summer, predation by migratory avian predators may act in concordance with mustelid predation to produce the long time lag necessary to drive the 3-yr cycle of voles, whereas almost direct density-dependent predation by all major predators in late summer may dampen spatial variation in prey densities.     

Size, shape and the distribution of organic matter in the Recent Antarctic brachiopod Liothyrella uva

The living terebratulid articulate brachiopod Liothyrella uva (Jackson 1912) was sampled from a shallow water population at Signy Island, South Orkney Islands, Antarctica. Neither shell height nor shell breadth were directly proportional to length and as a result there was a change in shell shape with size (and hence age); this change was small but statistically significant. The proportion of the total organic matter found in the shell and internal (mantle) tissues also changed with size. In small (5–7 mm length) brachiopods 70–80% of the total organic matter was located within the shell; this fraction decreased with increasing size until above about 25 mm length the proportion of organic matter in the shell was constant at 30–45%. Variability in this measure was influenced by infection with endolithic red algae. Punctal density was independent of size with a mean value of 95.7 per mm² [SE (standard error) ± 2.2], which was greater than in populations sampled from higher latitudes. With increasing shell length there was a slight increase in the size of puncta close to the shell edge. In all morphometric measures the range of variation observed was similar to that described from populations of Liothyrella from other areas of the Southern Ocean.     

Stunted growth of pikeperch Sander lucioperca in Lake Sahajärvi, Finland

Growth of pikeperch Sander lucioperca in the eutrophic and clay-turbid Lake Sahajärvi, Southern Finland, was extremely slow in comparison with other lakes at similar latitudes. The most important food item in July was phantom midge larvae Chaoborus flavicans for all sizes of S. lucioperca (239–423 mm total length L _T), while later, in August and September, the diet of S. lucioperca (149–407 mm L _T) consisted of small (30–100 mm L _T) perch Perca fluviatilis , ruffe Gymnocephalus cernuus and roach Rutilus rutilus .     

Juvenile recruitment, growth and maturation of Lipophrys pholis (Pisces: Blenniidae), from the west coast of Portugal

Data on the juvenile recruitment, growth and size at maturation of Lipophrys pholis in Portuguese waters are compared with the information available on the biology of this species at higher latitudes. In Portugal, recruitment extends for a much longer period, young fish grow faster and sexual maturation is earlier than at higher latitudes. There is a delay of 2–3 months between the appearance of the first eggs on the shore and the recruitment of the first juveniles to the pools.     

Size at maturity and egg capsules of the softnose skates Bathyraja brachyurops (Fowler, 1910) and Bathyraja macloviana (Norman, 1937) (Elasmobranchii: Rajidae) in the SW Atlantic (37°00'–39°30'S)

The softnose skates Bathyraja brachyurops and Bathyraja macloviana represent an important portion of the skate catches of the Uruguayan trawling fleet in the southwestern Atlantic. From March to October 2004, specimens of these species were collected at 75–200 m depth range in the area situated between latitudes 37°00'–39°30'S. For B. brachyurops , total length at which 50% of the specimens were retained by the gear was 68.0 cm for both sexes; T _L50 was estimated at 65.4 cm for males and 67.0 cm for females. For B. macloviana, total length at which 50% of the specimens were retained was 56.0–57.0 cm for both sexes; T _L50 was estimated at 53.5 cm for males and 52.0 cm for females. Egg capsule length varied from 79–91 mm in B. brachyurops and 69–75.5 mm in B. macloviana . In both species, capsules displayed striated surfaces and similar gross morphology, although egg capsules of B. macloviana had more robust anterior horns and a smaller size than those of B. brachyurops . Egg capsules of the latter also exhibited microscopical prickles. Capsule edges were laterally keeled with a groove along the keel, and a straight and transverse velum was present in the egg capsules of both species.     

Bergmann's rule in larval ant lions: testing the starvation resistance hypothesis

Abstract.  1. Body size of the ant lion Myrmeleon immaculatus follows Bergmann's rule – an increase in body size towards higher latitudes. The hypothesis that ant lion body size is larger in the north as an adaptation for starvation resistance was tested.
2. In a laboratory experiment testing starvation resistance, survivorship curves differed among 10 ant lion populations for both a starved and a fed treatment.
3. The average number of months survived by each population was correlated positively with latitude for both treatments. Across both treatments and all populations, large individuals survived longer than small individuals; however individuals from high latitudes had higher survivorship, even after factoring out variation due to initial body size.
4. These results suggest that starvation resistance may be an adaptation for coping with reduced prey availability in high latitudes. Starvation resistance may contribute to latitudinal gradients in body size of ant lions and other ectotherms.     

Dynamics of an immune response in house sparrows Passer domesticus in relation to time of day, body condition and blood parasite infection

European starlings ( Sturnus vulgaris ) introduced to North America compete with native cavity-nesting birds for nest sites. I examined whether natural selection could favour a strategy of delayed nesting in a population of northern flickers ( Colaptes auratus ), a native woodpecker, to reduce overlap in breeding phenology with starling competitors. I developed a mathematical model based on reproductive parameters for a population of flickers from central British Columbia, Canada. On average, 7% of flicker nests each year were usurped by starlings; daily probabilities of takeover declined through the season but were relatively low (1–2%). Flickers laid between 3 and 13 eggs and there was a negative correlation between clutch size and date. The probability of renesting after nest failure also declined during the season, but renesting intervals (2–19 days) were not associated with female age, or stage of nest loss. The model suggested that costs of delaying reproduction would outweigh benefits of an early start except when the probability of nest usurpation is very high (>75%) early in the season and declines rapidly through the summer. Thus, early laying dates should be favoured especially in northern latitudes where breeding seasons are short.     

Mollusk species diversity in the Southeastern Pacific: why are there more species towards the pole?

The most ubiquitous and well recognized diversity pattern at large spatial scales is the latitudinal increase in species richness near the equator and decline towards the poles. Although several exceptions to this pattern have been documented, shallow water mollusks, the most specious group of marine invertebrates, are the epitome of the monotonic decline in species diversity toward higher latitudes along the Pacific and Atlantic coasts of North America. Here we analyze the geographic diversity of 629 mollusk species along the Pacific South American shelf. Our analyses are based on the most complete database of invertebrates assembled for this region of the world, consisting of latitudinal ranges of over 95% of all described mollusks between 10° and 55°S. Along this coast, mollusk diversity did not follow the typical latitudinal trend. The number of species remained constant and relatively low at intermediate latitudes and sharply increased toward higher latitudes, south of 42°S. This trend was explained by changes in shelf area, but not by sea surface temperature, unlike the pattern documented for Northern Hemisphere mollusks. Direct sampling of soft bottom communities along the gradient suggests that regional trends in species richness are produced by increased alpha diversity, and not only by artifacts produced by the increase in sampling area. We hypothesize that increased shelf area south of 42°S, geographic isolation produced by divergence of major oceanic currents, and the existence of refugia during glaciations, enabled species diversification. Radiation could have been limited by narrow continental shelves between 10°–42°. Asymmetries in latitudinal diversity trends between hemispheres show that there is not a single general factor determining large-scale diversity patterns.     

Species traits explain recent range shifts of Finnish butterflies

This study provides a novel systematic comparative analysis of the species characteristics affecting the range margin shifts in butterflies towards higher latitudes, while taking phylogenetic relatedness among species into account. We related observed changes in the northern range margins of 48 butterfly species in Finland between two time periods (1992–1996 and 2000–2004) to 11 species traits. Species with positive records in at least ten 10 km × 10 km grid squares (in the Finnish National Butterfly Recording Scheme, NAFI) in both periods were included in the study. When corrected for range size change, the 48 butterfly species had shifted their range margins northwards on average by 59.9 km between the study periods, with maximum shifts of over 300 km for three species. This rate of range shifts exceeds all previously reported records worldwide. Our findings may be explained by two factors: the study region is situated in higher latitudes than in most previous studies and it focuses on the period of most prominent warming during the last 10–15 years. Several species traits exhibited a significant univariate relationship with the range margin shift according to generalized estimation equations (GEE) taking into account the phylogenetic relatedness among species. Nonthreatened butterflies had on average expanded their ranges strongly northwards (84.5 km), whereas the distributions of threatened species were stationary (−2.1 km). Hierarchical partitioning (HP) analysis indicated that mobile butterflies living in forest edges and using woody plants as their larval hosts exhibited largest range shifts towards the north. Thus, habitat availability and dispersal capacity of butterfly species are likely to determine whether they will be successful in shifting their ranges in response to the warming climate.     

Synaptic mutation associated with gametic sterility and population divergence in Coptis teeta (Ranunculaceae)

Cytogenetic investigations of 13 natural populations of Coptis teeta , an endemic and endangered medicinal plant from the Eastern Himalaya, were carried out. About 70–80% individuals in some of the populations were synaptic mutants. The predominantly sexually breeding plant populations were confined to higher cooler latitudes, whereas the mutant apomict inhabited lower warmer latitudes. The breeding systems were observed to be associated with morphological differentiation and ecological preference of some populations. Individuals of subsp. teeta reproduced sexually as well as vegetatively, but those of subsp. lohitensis have adapted almost entirely to a vegetative mode of reproduction. Though no variation was observed in somatic chromosome number and karyotypes, the two subspecies differed significantly with respect to their male meiotic behaviour and rhizome morphology. The mutants either produced little fertile pollen or were completely sterile, leading to low seed production or none at all. This has resulted in low reproductive fitness, localized distribution and small population sizes of the taxon.     

Latitudinal trends in Spartina alterniflora productivity and the response of coastal marshes to global change

Marshes worldwide are actively degrading in response to increased sea level rise rates and reduced sediment delivery, though the growth rate of vegetation plays a critical role in determining their stability. We have compiled 56 measurements of aboveground annual productivity for Spartina alterniflora , the dominant macrophyte in North American coastal wetlands. Our compilation indicates a significant latitudinal gradient in productivity, which we interpret to be determined primarily by temperature and/or the length of growing season. Simple linear regression yields a 27 g m⁻² yr⁻¹ increase in productivity with an increase of mean annual temperature by 1 °C. If temperatures warm 2–4 °C over the next century, then marsh productivity may increase by 10–40%, though physiological research suggests that increases in the north could potentially be offset by some decreases in the south. This increase in productivity is roughly equivalent to estimates of marsh lost due to future sea level change. If a warming-induced stimulation of vegetation growth will enhance vertical accretion and limit erosion, then the combined effects of global change may be to increase the total productivity and ecosystem services of tidal wetlands, at least in northern latitudes.     

Evolution of life history traits in Leporidae: a test of nest predation and seasonality hypotheses

Recently, it has been proposed that adult mortality schedules may be responsible for latitudinal patterns of life history variation in passerine birds, whereas nest predation only could explain within latitude patterns. Unfortunately, no independent test has been performed regarding the importance of nest predation with different taxa. In the present study, seasonality and nest predation hypotheses explaining variations in gestation time and litter size in 17 lagomorph species were tested. Among latitude patterns were analysed using the phylogenetic independent contrast method of Felsenstein and within latitude patterns were analysed by the pairwise comparative method. The results obtained indicate that latitudinal patterns observed in both variables are explained by different factors: seasonality for litter size and nest predation for gestation time. Litter size variations within latitudes are also explained by differences in nest predation, supporting previous hypotheses. In conclusion, the present study suggests that, when compared among latitudes, different life history traits (e.g. litter size and gestation time) may be shaped by different selective forces and that the effects of nest predation may be high both within and between latitudes.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 88 , 603–610.     

Giraudia sphacelarioides (Phaeophyceae) at the Canary Islands and in Danish waters: a study in ecotypic differentiation and its biogeographical implications

Comparative culture studies on isolates from Lanzarote (Canary Islands) and from Danish waters of Giraudia sphacelarioides show that temperature plays the key role to determine its geographical distribution. Experiments show that the upper lethal temperature is the same for both isolates 26.5—-31.1°C for microthalli, and formation of macrothalli is inhibited between 23.2 and 26.5°C. The lower lethal temperature for both micro- and macrothalli in the Lanzarote isolate is between 10.8° C and 7.6°C, while the Danish isolate survives 54°C. The microthallus is thus the more persistent stage in relation to temperature, while the macrothalli occur only when more suitable conditions exist in nature. In the North Atlantic Ocean G. sphacelarioides is distributed over approximately 30° latitudes with severe winter temperatures especially in Danish waters. This distribution can only be explained by ecotypic differentiation. In Danish waters salinity decreases from c. 30 ‰ in the northern Kattegat to below 8 ‰ in the inner parts and therefore becomes an important factor for the immigration of species into the Baltic Sea. Combined salinity (30–20–10–5 ‰) and temperature (4 to 30°C) experiments show that the Lanzarote isolate only grows at 20 ‰ in an attenuated temperature interval and at 10 ‰ only fertile microthalli are observed, however, with limited liberation of swarmers. The Danish isolate grows and reproduces also at salinities from 20–5 ‰ both as microand macrothalli, but in a still more attenuated temperature interval, and the morphology of the macrothalli becomes increasingly aberrant vs. decreasing salinity. This is in agreement with the fact that G. sphacelarioides is reported from the northern part of Kattegat with salinity from 28—-25 ‰, and it is only recorded a few times in the southern part of Kattegat and limited by the 10 ‰ isohaline.     

Observations of social and reproductive biology of the bent-winged bat Miniopterus australis in northern Borneo

The small bent-winged bat Miniopterus australis was studied at low tropical latitudes north of the equator, principally in Subis cave, Niah, Sarawak, East Malaysia. During the course of field-work in 1957–58, most specimens were captured at roost in concavities in the cave ceiling, here termed "cupolas". At all months of observation, roosting groups varied from one to seven bats. Solitary bats were predominantly males, and multiple groups rarely included more than one male. It is suggested that the sexes differ in their response to a potential or familiar roosting site, depending on the prior occupation by other bats. Roosting behaviour did not vary with the progress of the reproductive cycle and seemed to have no epigamic function.
Observations of reproductive biology in 1957–58, supported by specimens captured in 1959–60, demonstrated that the species is monoestrous, with a brief annually recurrent breeding season in November-December. Copulation was observed in early November and preceded ovulation. In unovulated females taken in early December the right uterine horn was distended with spermatozoa. The single embryo subsequently implanted in the right horn, although in the three females examined the fertilized ovum derived from the left ovary.
Parturition occurred in late April and early May after a gestation period of 4 1/2–5 months. This period is considerably longer than the presumed species-specific minimum, observed at latitude 15 S. The prolonged gestation period is regarded as an adaptation to perennially low and variable food resources in an otherwise favourable environment, and there is evidence that the months of gestation and birth coincide with a period of limited seasonal increase in abundance of insect prey.     

Failure to migrate: lack of tree range expansion in response to climate change

Tree species are expected to track warming climate by shifting their ranges to higher latitudes or elevations, but current evidence of latitudinal range shifts for suites of species is largely indirect. In response to global warming, offspring of trees are predicted to have ranges extend beyond adults at leading edges and the opposite relationship at trailing edges. Large‐scale forest inventory data provide an opportunity to compare present latitudes of seedlings and adult trees at their range limits. Using the USDA Forest Service's Forest Inventory and Analysis data, we directly compared seedling and tree 5th and 95th percentile latitudes for 92 species in 30 longitudinal bands for 43 334 plots across the eastern United States. We further compared these latitudes with 20th century temperature and precipitation change and functional traits, including seed size and seed spread rate. Results suggest that 58.7% of the tree species examined show the pattern expected for a population undergoing range contraction, rather than expansion, at both northern and southern boundaries. Fewer species show a pattern consistent with a northward shift (20.7%) and fewer still with a southward shift (16.3%). Only 4.3% are consistent with expansion at both range limits. When compared with the 20th century climate changes that have occurred at the range boundaries themselves, there is no consistent evidence that population spread is greatest in areas where climate has changed most; nor are patterns related to seed size or dispersal characteristics. The fact that the majority of seedling extreme latitudes are less than those for adult trees may emphasize the lack of evidence for climate‐mediated migration, and should increase concerns for the risks posed by climate change.     

Relationship between laying dates of black kites Milvus migrans and spring temperatures in Italy: rapid response to climate change?

Many Holarctic bird species have been shown to be laying progressively earlier in response to global warming. Most studies have been conducted on small-bodied species at northern latitudes. In Italy, black kite Milvus migrans populations are concentrated near large pre-Alpine lakes, whose water temperatures have been increasing steadily in recent decades. Annual black kite laying dates have become 10–11 days earlier during the last nine years. This shift was related to temporal variations in spring air temperatures, with earlier laying in warmer springs. The progressive advancement in laying dates was not associated with an increase in population level productivity, despite the fact that productivity declined with laying date at the individual territory level within years. Avian response to climate change may be occurring more rapidly than previously thought, even in relatively long-lived species, and not only at the most northern latitudes or highest elevations. Because this change has occurred so rapidly, and because laying dates match annual variations in spring temperatures, the response must be facultatively driven by prevailing conditions, rather than genetic in response to natural selection.     

Holocene carbon burial by lakes in SW Greenland

The role of the Arctic in future global change processes is predicted to be important because of the large carbon (C) stocks contained in frozen soils and peatlands. Lakes are an important component of arctic landscapes although their role in storing C is not well prescribed. The area around Kangerlussuaq, SW Greenland (66–68°N, 49–54°W) has extremely high lake density, with ∼20 000 lakes that cover about 14% of the land area. C accumulation rates and standing stock (kg C m⁻²), representing late- to mid-Holocene C burial, were calculated from AMS ¹⁴C-dated sediment cores from 11 lakes. Lake ages range from ∼10 000 cal yr  bp to ∼5400 cal yr  bp , and reflect the withdrawal of the ice sheet from west to east. Total standing stock of C accumulated in the studied lakes for the last ∼8000 years ranged from 28 to 71 kg C m⁻², (mean: ∼42 kg C m⁻²). These standing stock determinations yield organic C accumulation rates of 3.5–11.5 g C m⁻² yr⁻¹ (mean: ∼6 g C m⁻² yr⁻¹) for the last 4500 years. Mean C accumulation rates are not different for the periods 8–4.5 and 4.5–0 ka, despite cooling trends associated with the neoglacial period after 4.5 ka. We used the mean C standing stock to estimate the total C pool in small lakes (<100 ha) of the Kangerlussuaq region to be ∼4.9 × 10¹³ g C. This C stock is about half of that estimated for the soil pool in this region (but in 5% of the land area) and indicates the importance of incorporating lakes into models of regional C balance at high latitudes.     

Clutch size, brood size and brood emergence in the Marbled Teal Marmaronetta angustirostris in the Marismas del Guadalquivir, southwestern Spain

The first detailed study of the breeding biology of the globally threatened Marbled Teal Marmaronetta angustirostris is presented, using data from the Marismas del Guadalquivir in southwestern Spain. Complete clutches, with 9–20 eggs, were recorded from 28 April to 27 July. Excluding clutches of over 14 eggs (likely to be intraspecifically parasitized), the mean clutch size was 11.8, larger than that reported for almost all other Anatidae species. Broods hatched from May to early August (later than sympatric duck species), with a peak in mid-late June and significant annual variation in date. Brood sizes were exceptionally high, declining from a mean of 10.9 in the first week of age to 8.5 when fully feathered (at 42 days or more). Duckling mortality was concentrated in the first 2 weeks after hatching. Nine percent of broods had 15–23 ducklings, largely as a result of nest parasitism. Brood size decreased strongly with hatching date and varied significantly between years. Data from across the species' range showed that breeding occurs later at more northerly latitudes. A recent decline in the Marbled Teal in the Marismas is linked with its late breeding season. Anthropogenic changes have reduced the duration of flooding in the natural marshes of Donana National Park, which now dry out by August, before this species has completed breeding     

Microbial Progression in Sliced Vacuum Packaged Bacon at Refrigeration Temperatures

S ummary . Three hundred and forty eight strains of micro-organisms were isolated from packaged bacon which had been cured by one or other of 2 methods (A and B) and stored at 0–10° for 7 weeks. Before storage, Micrococcus sub-group 7 (47%) and coryneform bacteria (33%) were the principal contaminants of bacon cured by method A and Micrococcus subgroup 1 (20%) and Microbacterium thermosphactum (21%), in bacon cured by method B. After 7 days at 0°, coagulase negative staphylococci accounted for 10 and 33% of the microflora in bacon A and B, respectively: other organisms were micrococci, 60% (A) and 25% (B); corynebacteria, 20% (A) and 12·5% (B), yeasts ( Torulopsis candida and T. dattila ) 5% (A) and 29% (B). In the following month at 10°, Micrococcus sub-group 5 was the dominant (43–88%) contaminant of bacon B; the incidence of Streptococcus Group N ranged from 27–36% and that of unidentified lactic acid bacteria from 23–32%. Towards the end of storage, the order of dominance was Micrococcus sub-group 3 (38–58%) and atypical streptobacteria (38%) in A; Streptococcus Group N (42%) and Gram positive rods (5–20%) in B. Staphylococci tended to die out during storage of bacons cured by the 2 methods and coagulase positive staphylococci were not isolated.