Southern Montane Research Articles

Montane refugia isolation and plateau population expansion: Phylogeography of Sino‐Himalayan endemic Spenceria ramalana (Rosaceae)

AbstractClimate oscillations and landscape heterogeneity make the historical population processes of organisms of the Qinghai–Tibet Plateau quite complex. We used chloroplast DNA sequences and amplified fragment length polymorphism (AFLPs) to study the phylogeography and genetic variation of the Qinghai–Tibet Plateau endemic Spenceria ramalana Trimen. The parsimony network contains two star‐like evolutionary units, nested into two nested clades, coinciding with geographic population groups indicated by SAMOVA software. The central group shows genetic homogeneity, indicating a bottleneck or founder effect of population dynamics. Margin groups contribute more haplotype diversity (CT), indicating potential refugia. Several expansion events during several interglacial periods were detected. The latest expansion of the eastern population contributed to the modern population structure of the central area. Four AFLP clusters were detected. Higher CT, a relict pattern of haplotype distribution and DW values of marginal populations, confirmed the location of potential montane refugia. Relict distribution pattern, nested clade phylogeographic analysis conclusions, and restricted gene flow detected by AFLPs indicated an isolation pattern of the populations of montane areas. Heterogeneity of landscape of the western and southern montane areas could be the main barrier for gene flow. Moisture conditions and ecotype transformation might help to build the phylogeographic pattern of this species. Neither chloroplast DNA markers nor AFLP was able to differentiate the two varieties of this species.

Southern montane populations did not contribute to the recolonization of West Siberian Plain by Siberian larch (Larix sibirica): a range‐wide analysis of cytoplasmic markers

While many species were confined to southern latitudes during the last glaciations, there has lately been mounting evidence that some of the most cold-tolerant species were actually able to survive close to the ice sheets. The contribution of these higher latitude outposts to the main recolonization thrust remains, however, untested. In the present study, we use the first range-wide survey of genetic diversity at cytoplasmic markers in Siberian larch (Larix sibirica; four mitochondrial (mt) DNA loci and five chloroplast (cp) DNA SSR loci) to (i) assess the relative contributions of southern and central areas to the current L. sibirica distribution range; and (ii) date the last major population expansion in both L. sibirica and adjacent Larix species. The geographic distribution of cpDNA variation was uninformative, but that of mitotypes clearly indicates that the southernmost populations, located in Mongolia and the Tien-Shan and Sayan Mountain ranges, had a very limited contribution to the current populations of the central and northern parts of the range. It also suggests that the contribution of the high latitude cryptic refugia was geographically limited and that most of the current West Siberian Plain larch populations likely originated in the foothills of the Sayan Mountains. Interestingly, the main population expansion detected through Approximate Bayesian Computation (ABC) in all four larch species investigated here pre-dates the LGM, with a mode in a range of 220,000-1,340,000 years BP. Hence, L. sibirica, like other major conifer species of the boreal forest, was strongly affected by climatic events pre-dating the Last Glacial Maximum.

Geographical patterns of congruence and incongruence between correlative species distribution models and a process‐based ecophysiological growth model

AbstractAimOur aim was to map the climate dependence of tree species distributions (probability of occurrence) and forest growth (net primary productivity) by comparing the congruence and incongruence between correlative and process‐based modelling approaches.LocationIberian Peninsula, south‐western Europe.MethodsWe used forest inventory data for three widespread tree species (Quercus ilex, Pinus halepensis and Pinus sylvestris) to model climatic suitability with an ensemble of seven correlative species distribution models (using biomod). We then simulated forest net primary productivity (NPP) as a surrogate of forest growth for forests of each species using an ecophysiological process‐based model (gotilwa+) along a gradient of climatic suitability. The spatial distribution of the growth estimates was then compared with that of the suitability estimates, and robust regression was used to classify regions in terms of model congruence.ResultsQuercus ilex and P. sylvestris both showed a positive relationship between forest NPP and climatic suitability. The main discrepancies were found in the north of the peninsula, where there was high potential forest growth but low climate suitability. Low forest‐growth estimates in areas of high suitability only appeared for P. sylvestris in southern montane regions. Pinus halepensis always showed a negative relationship between estimated growth and climatic suitability. The analysis of other ecophysiological parameters (mean leaf life and leaf area index) suggests that this tree species has different physiological strategies that allow differential growth rates in areas of low suitability.Main conclusionsWe found that the relationship between estimated growth and distribution varies strongly in different areas and species. Mapping the incongruences between the predicted climatic suitability and growth allowed us to identify regions where other factors (e.g. biotic interactions) may be more significant than the physiological limits on growth. We show that new insights into species distributions can be gained from mapping the differences between correlative and process‐based models.

Naturalization of Sequoiadendron giganteum (Cupressaceae) in Montane Southern California

After the August 1974 fire in the upper Hall Canyon area on the southwestern flank of Black Mountain in the northwestern San Jacinto Mountains, Riverside County, California, the United States Forest Service revegetated the burn in the mixed-conifer forest with the Sierra Nevada endemic Sequoiadendron giganteum (Cupressaceae). On 1 May 2009 a GPS census starting at the head of Hall Canyon revealed both in the canyon and upslope beyond it at least 157 individuals in the vicinity of the Black Mountain Trail, plus an outlier 450 m distant near the summit. This species alien to southern California is regenerating prolifically on Black Mountain, as revealed by multiple age classes, from juveniles (seedlings and saplings) about 20–60 cm tall to young adult trees over 6 m tall, up to about 40 years old, and reproductively mature. The naturalized population (2009) also appears to be spreading from its initial ''small area'' of introduction (1974). Analysis of published print and Internet literature suggests similar post-fire naturalizations of S. giganteum in the San Gabriel and San Bernardino Mountains of Los Angeles and San Bernardino Counties. State and regional floras and checklists for California should acknowledge the naturalization of this species in montane southern California in the San Jacintos and possibly elsewhere.

Genetic diversification without obvious genitalic morphological divergence in harvestmen (Opiliones, Laniatores, Sclerobunus robustus) from montane sky islands of western North America

The southern Rocky Mountains and adjacent Intermontane Plateau Highlands region of western North America is a geographically diverse area with an active geologic history. Given the topological complexity and extensive geologic activity, organisms inhabiting this region are expected to show some degree of morphological and genetic divergence, especially populations found on the southern montane ‘sky islands’ of this region. Here we examine the phylogeographic history and diversification of a montane forest inhabiting harvestmen, Sclerobunus robustus, using a combination of genetic and morphological data. Divergence time estimates indicate that much of the diversification within and between major groups S. robustus predate the Pleistocene glacial cycles. The most widespread subspecies, Sclerobunus robustus robustus, is recovered as six genetically distinct, geographically cohesive mitochondrial phylogroups. Gene tree data for a single nuclear gene reveals congruent, albeit slightly more conservative, patterns of genetic divergence. Despite high levels of genetic divergence throughout their distribution, phylogroups show extreme conservation in somatic and reproductive morphology. This uncoupling of morphological and genetic differentiation may be due to morphological conservatism associated with a conserved microhabitat preference. Based on these data, it is obvious that S. robustus has undergone some level of cryptic diversification.

Reduced growth and survival of vascular epiphytes on isolated remnant trees in a recent tropical montane forest clear-cut

Forest fragmentation can negatively affect tropical epiphyte diversity, but the processes leading to such impoverishment are insufficiently understood. Due to a lack of experimental studies, the relative influence of dispersal constraints vs. growth conditions remains particularly controversial. This paper addresses the fate of late juvenile and adult vascular epiphytes in response to severe forest disturbance in montane southern Ecuador. Plant growth and survival on trunks and lower branches of isolated remnant trees was studied for the first three years following clear-cutting. Overall epiphyte mortality was substantially increased on remnant trees (72% over 3 years) relative to undisturbed forest (11%). Mortality on remnant trees was higher during the first year (52%) than during the second (20%) and third year (26%). Pteridophytes and dicots suffered higher losses than monocots. Plants surviving on remnant trees generally showed a marked negative growth regarding maximum leaf length, whereas the annual increment in leaf number varied more strongly among taxa (families). The present study provides the first field-experimental evidence for the adverse effects of forest disturbance on the performance of later, well-established life stages of vascular epiphytes. The results suggest that growth conditions may often be a more important predictor of epiphyte diversity in disturbed habitats than dispersal constraints. Similar plant responses can be expected to occur along forest edges. Therefore, the retention of scattered green trees, narrow strips or small fragments of forest are unlikely to be sufficient management tools for the conservation of epiphyte diversity in tropical landscapes.

Geographical trends in the yolk carotenoid composition of the pied flycatcher (Ficedula hypoleuca).

Carotenoids in the egg yolks of birds are considered to be important antioxidants and immune stimulants during the rapid growth of embryos. Yolk carotenoid composition is strongly affected by the carotenoid composition of the female’s diet at the time of egg formation. Spatial and temporal differences in carotenoid availability may thus be reflected in yolk concentrations. To assess whether yolk carotenoid concentrations or carotenoid profiles show any large-scale geographical trends or differences among habitats, we collected yolk samples from 16 European populations of the pied flycatcher, Ficedula hypoleuca. We found that the concentrations and proportions of lutein and some other xanthophylls in the egg yolks decreased from Central Europe northwards. The most southern population (which is also the one found at the highest altitude) also showed relatively low carotenoid levels. Concentrations of β-carotene and zeaxanthin did not show any obvious geographical gradients. Egg yolks also contained proportionally more lutein and other xanthophylls in deciduous than in mixed or coniferous habitats. We suggest that latitudinal gradients in lutein and xanthophylls reflect the lower availability of lutein-rich food items in the northern F. hypoleuca populations and in montane southern populations, which start egg-laying earlier relative to tree phenology than the Central European populations. Similarly, among-habitat variation is likely to reflect the better availability of lutein-rich food in deciduous forests. Our study is the first to indicate that the concentration and profile of yolk carotenoids may show large-scale spatial variation among populations in different parts of the species’ geographical range. Further studies are needed to test the fitness effects of this geographical variation.

Systematic revision, cladistics and biogeography of the genus Neogutierrezia Martínez (Coleoptera:Scarabaeidae) and its phylogenetic placement in Rutelinae based on structural alignment of 28S rDNA sequences

The Argentinean endemic genus Neogutierrezia Martínez, 1953 (Scarabaeidae : Rutelinae) is revised and seven new species are described: N. bicolor Ocampo & Ruiz-Manzanos, sp. nov., N. chelii Ocampo & Ruiz-Manzanos, sp. nov., N. galileoi Ocampo & Ruiz-Manzanos, sp. nov., N. lagosae Ocampo & Ruiz-Manzanos, sp. nov., N. payuniensis Ocampo & Ruiz-Manzanos, sp. nov., N. scutata Ocampo & Ruiz-Manzanos, sp. nov. and N. variabilis Ocampo & Ruiz-Manzanos, sp. nov. Species status is proposed for N. affinis Martínez stat. nov., which was formerly considered as subspecies of N. mirabilis Martínez. The genus Neogutierrezia now includes 10 species distributed in the Monte biogeographic province in Argentina. In order to clarify the systematic placement of the genus Neogutierrezia, a molecular phylogenetic analysis was performed using structurally aligned 28S rDNA sequences (expansion segments D2 and D3) from 23 taxa in Scarabaeoidea, including two representative species of Neogutierrezia. This is the first report of an annotated secondary structure alignment of the D2 and D3 segments of 28S rRNA that spans a wide sample of scarabaeoids, providing a useful homology template for further phylogenetic reconstruction in these and closely related beetles. Results of the molecular parsimony analysis strongly indicate that the genus is closely related to members of the Rutelinae (Scarabaeidae), and thus Neogutierrezia Martínez is transferred from Melolonthinae: Pachydemini to Rutelinae, new placement. A morphological cladistic analysis of the genus was also undertaken, including all the 10 known species in the genus plus two outgroup taxa in Rutelinae, and based on 53 adult characters. The most-parsimonious cladogram provides evidence for the monophyly of the genus, which shows three main clades, distributed in Central Monte and Southern Monte. The adult morphology of the 10 species is described and a key is provided, along with illustrations of the diagnostic characters. The biogeography of species in the genus is discussed.

Molecular systematics of eastern North American Phalangodidae (Arachnida: Opiliones: Laniatores), demonstrating convergent morphological evolution in caves

The phalangodid harvestmen (Opiliones: Laniatores) fauna of the southeastern United States has remained obscure since original descriptions of many genera and species over 60 years ago. The obscurity of this interesting group is pervasive, with uncertainty regarding basic systematic information such as generic limits, species limits, and geographic distributions. This situation is unfortunate, as the fauna includes several cave-obligate forms of interest from both conservation and evolutionary perspectives, and the group likely exhibits interesting biogeographic patterns because of their low dispersal ability. Here, we use DNA sequence data from two genes to reconstruct phylogenetic relationships of southeastern phalangodid taxa, for a sample of all described genera from the region. Our results demonstrate that the southeastern fauna is likely monophyletic, and is most-closely related to western North American phalangodids with a similar penis morphology. Within the southeastern clade, trends in the evolution of penis morphology correspond broadly to molecular phylogenetic patterns, although penis evolution is overall relatively conservative in the group. Biogeographically, it appears that western taxa in the southeast (i.e., from west of the Appalachian Valley) are early diverging, with later diversification in the montane southern Blue Ridge, and subsequent diversification back towards the west. This W>E>W pattern has been observed in other groups from the southeast. The multiple cave-modified species in the region are genetically divergent and appear phylogenetically isolated; explicit topological hypothesis testing suggests that troglomorphism has evolved convergently in at least three independent lineages. The total number of species in the region remains uncertain-mitochondrial COI data reveal many highly divergent, geographically coherent groups that might represent undescribed species, but these divergent mitochondrial lineages do not always exhibit divergence in either nuclear sequences or penis morphology. Many questions remain, but our studies provide a solid framework for further systematic investigations of this interesting group.

Dark Color of the Coastal Plain Swamp Sparrow (Melospiza georgiana nigrescens) May Be an Evolutionary Response to Occurrence and Abundance of Salt-tolerant Feather-degrading Bacilli in Its Plumage

ABSTRACT. The Southern Swamp Sparrow (Melospiza georgiana georgiana) breeds in northeastern North America in montane, freshwater marshes and fens. Its close relative, the Coastal Plain Swamp Sparrow (M. g. nigrescens), breeds in northeastern North America, but in coastal salt marshes. Coastal Plain Swamp Sparrows are darker than Southern Swamp Sparrows. Darkly colored feathers are more resistant to bacterial degradation by bacilli, which are unusually salt-tolerant. We tested whether the difference in feather color of the pale montane Southern Swamp Sparrow and the dark Coastal Plain Swamp Sparrow could be an adaptive response to differences in the occurrence and activity of bacilli in habitats that differ in salinity. Southern Swamp Sparrows were caught and sampled in cranberry fens in western Maryland, whereas Coastal Plain Swamp Sparrows were sampled in salt marshes on the western shore of the Delaware River, just where it broadens into Delaware Bay. The number of birds with feather-degrading bacteria ...

STREPTANTHUS LONGISILIQUS (BRASSICACEAE), A NEW SPECIES FROM NORTHEASTERN CALIFORNIA

Streptanthus longisiliqus G. Clifton & R. Buck is described as a new species from Butte, Tehama, and Shasta counties in northeastern California. The new species is a short-lived perennial in subgenus Pleiocardia, informal group Cordati. Based on several morphological characters, S. longisiliqus appears to be most closely related to the montane southern California species S. bernardinus and S. campestris; it is geographically disjunct from those taxa by approximately 600 km. Streptanthus longisiliqus occurs in montane coniferous forest, often in localized openings, and sometimes in disturbed places.

Potential impact of climatic change on the distribution of forest herbs in Europe

The aim of this study is to evaluate the possible consequences of climate change on a representative sample of forest herbs in Europe. A fuzzy climatic envelope was used to predict the location of suitable climatic conditions under two climatic change scenarios. Expected consequences in terms of lost and gained range size and shift in distribution for 26 forest herbs were estimated. These results were combined in an Index of Predicted Range Change for each species. Finally, the effects of habitat fragmentation for potential dispersal routes were evaluated and options for management on a European scale are discussed.Generally, a good agreement of the estimated suitability under the present climate and the observed current distribution was observed. However, species vary a lot in the degree to which they occupy the presently climatically suitable areas in Europe. Many species are absent from large areas with suitable climate and thus could be said to have poor range‐filling capacity.A general change in location (range centroid) of the total suitable area was observed: The total suitable area will on average move strongly northwards and moderately eastwards under the relatively mild B1 scenario and more strongly so under the A2 scenario. The required average minimum migration rate per year to track the potential range shift is 2.1 km under the B1 scenario and 3.9 km under the A2 scenario.Moderate losses in the total suitable area in Europe are predicted for most species under both scenarios. However, the predicted changes are very variable, with one species (Actaea erythrocarpa) experiencing total range elimination in Europe (A2 scenario) while the total suitable area is predicted to show large increases for other species. The species that are predicted to experience the greatest proportional losses in their climatically suitable area within their presently realised range tend to have northern or eastern range centroids.The Index of Predicted Range Change roughly divides the species studied in four groups: One species face a high risk of extinction; eight species are expected to experience moderate to severe threat of extinction; 11 species are not considered at risk and, finally, six species may actually benefit from global warming.An analysis of potential migration routes shows the importance of maintaining and, if possible, improving the network of forest throughout Europe to make migration possible. It is also suggested to closely monitor the status of boreal and subalpine species that are most threatened by global warming. Finally it is recommended that special concern should be given to increased protection and restoration of forest habitats in southern montane areas for their crucial long‐term importance for the maintenance of European plant diversity.

Amphibian population declines in montane southern Mexico: resurveys of historical localities

Declines of amphibian populations have been well documented in the US, Canada, and Central America, but little is known regarding the status of amphibian populations in Mexico. In 2000, we surveyed 43 transects from 3 upland regions in Guerrero and Oaxaca, Mexico. We found 161 adult amphibians belonging to 39 species, representing only 19–48% of the anuran fauna known from these regions. We found one dead ( Eleutherodactylus saltator) and one dying frog ( Ptychohyla erythromma) from two different streams near Chilpancingo, Guerrero. Both frogs were infected with Batrachochytridium dendrobatidis, a pathogenic fungus involved in other declines of amphibian populations. We collected 368 tadpoles; 60 (19%) tadpoles from 9 different streams among the three regions were missing mouthparts, which is indicative of infection by chytrid fungus. We report additional data from the state of Chiapas, Mexico, that document declines, disease, and apparent extirpations from that region as well. Overall, we report 31 populations (representing 24 species) that appear to have been extirpated, including populations of as many as 11 endemic species that have been missing for 16–40 years and may be extinct.

Temporal and micro-spatial patterning of seedling establishment. Consequences for patch dynamics in the southern Monte, Argentina

We compared the temporal and micro-spatial patterning of seedling emergence and establishment of two cohorts of perennial grasses and shrubs in the southern Monte, Argentina. Samplings were carried out in two contrasting areas (grazed and non-grazed) during four years. We found lower densities of emerged and established seedlings of perennial grasses in the grazed relative to the non-grazed area. Conversely, emerged seedlings of shrubs did not vary between the grazed and the non-grazed area and densities of established shrub seedlings were higher in the grazed than in the non-grazed area. We only found differences between cohorts in seedling emergence of perennial grasses. These differences could be associated with the amount of precipitation in the year previous to the emergence. Both in the grazed and non-grazed area, seedlings of perennial grasses were concentrated at the periphery of plant patches. We defined a plant patch as a discrete unit of the spatial pattern of vegetation surrounded by, at least, 20 cm of bare soil from the nearest neighbour patch. Emergence in perennial grasses was more frequent at the southern/western patch-periphery than at other patch-periphery locations. Established seedlings of perennial grasses, however, were homogeneously distributed throughout patch periphery. Emergence in shrubs was more frequent at the centre and periphery of patches than at inter-patch microsites. In contrast, established seedlings of shrubs were homogeneously distributed among microsites. Our results suggests that differential seedling establishment between life forms is the outcome of complex biotic and abiotic interactions and feedbacks at the patch level between seedlings and established plants. Both life forms appear to have a different role in the origin, dynamics, and maintenance of spotting vegetation. Because of the ability to establish both at inter-patch and patch microsites, shrubs could be identified as colonizers or initiators of small plant patches in bare soil or they may contribute to increase the cover and size of pre-existing plant patches. Both processes would be promoted in grazed areas. Due to the ability to establish at patch peripheries, perennial grasses would contribute to the isodiametric growth of pre-existing patches, preferentially in non-grazed areas.

Seed removal by birds, rodents and ants in the Austral portion of the Monte Desert, Argentina

The relative importance of granivory by birds, rodents and ants in the southern Monte Desert (Argentina) was examined using an experimental seed–dish technique. Monthly seed-removal rates were recorded during two consecutive years, from September’ 1995 to August’ 1997. Birds were the main and most constant seed eaters during the study period. There was no seed removal by ants in September’ 95, April, June, and July’ 96, and May, June and August’ 97. There was no consumption by rodents from March to May’ 96. Rodents consumed significantly more seeds than did ants during both winters, and spring' 96. Conversely, seed removal by ants was significantly higher than that of rodents in summer 96. Overall removal rates were significantly different between both annual cycles studied. The highest seed-removal rate was recorded in March 1997. We compare our results with those obtained by several authors at the northern and central Monte Desert, as well as other arid and semi-arid regions of the World, reevaluating conclusion about granivory in South American arid zones.

Biogeographic differences in shoot elongation pattern among European Scots pine populations

Abstract Results are presented of shoot elongation of 10-year-old trees of 19 European Pinus sylvestris populations growing in a provenance experiment in central Poland. Populations exhibited different shoot elongation patterns with montane southern (40–44°N) and lowland northern (58–60°N) populations having lower growth rates and earlier onset of growth cessation than those from the central lowland part (47–55°N) of European species’ range. Average absolute growth rates ranged from 6.6 mm per day for populations of southern origin to 9.2 mm per day for populations from central Europe. Shoot elongation period explained ca. 50–60% and differences in growth rate from 40 to 50% of total differences in annual increment among population groups. There was a linear relationship ( r 2 =0.73, P

The peninsula effect on species diversity: a reassessment of the avifauna of Baja California

The peninsula effect, a decrease in species diversity from the base to the tip of peninsulas, has been proposed to explain the relatively poor species diversity of mammals on North American peninsulas. Subsequent work has questioned both the existence of peninsular declines in diversity, as well as the proposed cause (immigration‐extinction dynamics). Previous studies of the Baja California avifauna have shown a gradual decrease in the diversity of breeding birds from the base to the tip of the peninsula. Using newly published data on the breeding land birds, I found a decrease only from the base to the middle of the peninsula, with a slight increase in diversity from the middle to the tip. This result is similar to that for other highly vagile taxa (e.g., Chiroptera. Lepidoptera) and is largely due to the coneave diversity gradient of montane species along the peninsula. Habitat associations of the Baja avifauna and the location of potential source populations suggest that: 1) local habitat heterogeneity is likely the single most important factor influencing the avian diversity gradient along the peninsula; and 2) limited immigration of Neotropical species from mainland areas, and of Nearctic species from the base of the peninsula to the montane southern tip is partly responsible for the form of the diversity gradient along the southern half of the peninsula. My results along with those from previous studies, suggest that rather than colonization/extinction dynamics, habitat heterogeneity and the vagility of the taxa considered have the greatest impact on the observed patterns of species diversity along peninsulas,

Habitat Selection and Survival of Mule Deer: Tradeoffs Associated with Migration

We examined tradeoffs related to migration in a population of mule deer ( Odocoileus hemionus ) in southern California from 1989 to 1991. All male deer that we radiocollared were migratory, whereas females exhibited a mixed strategy with both migrant and resident individuals. Increased movements of deer were associated with decreased temperatures and increased weekly precipitation. No differences within seasons in the sizes of home ranges occurred for either migrant or resident deer. The size of home ranges of deer, however, was smaller in summer than in winter. Sizes of home ranges were associated positively with proximity to human development and to the amount of avoided (use was less than availability) habitat in the home range. Deer avoided human developments in all seasons. Further, males and resident females used areas farther from water in summer than expected by chance, whereas migratory females selected areas nearer to water. In summer, migratory females selected meadows, riparian habitats, and pine forests, whereas resident females avoided riparian habitats and used pine forests less than did migratory females. Migratory males used habitats in a way similar to migratory females, although they avoided meadows and riparian areas. Clear tradeoffs existed for deer in montane southern California about whether they migrated. Migratory females were farther from human disturbance and used habitats of high quality more often than did nonmigratory conspecifics. Nonetheless, deer were at increased risk of predation during migration and, in years of low precipitation (low snow), had higher rates of mortality than did resident deer. Thus, in areas with extremely variable precipitation and snow cover, a mixed strategy for migration can be maintained in populations of mule deer.

Needle Respiration and Nitrogen Concentration in Scots Pine Populations from a Broad Latitudinal Range: A Common Garden Test with Field-Grown Trees

Models of tree function and forest ecosystem carbon budgets often assume that potential global changes in temperature and/or other factors may alter tissue nitrogen (N) and dark respiration rates (R d ). However, little is known of patterns of co-variation in tissue N and R d among intraspecific populations originating along climatic gradients, and of whether an N-based model of R d can link these two variables. To address these issues, we studied N and R d in fully expanded needles of 10-year-old trees of 14 Scots Pine (Pinus sylvestris) populations of wide-ranging origin (43 ° to 60 °N), grown under common garden conditions. For 11 lowland populations (elevation < 200 m) from the contiguous part of the species range (48 ° to 60°N) grown at a field site in Kornik, western Poland (52 °N), there were greater needle %N in populations from increasing latitude of origin or decreasing mean annual temperature (r≥0.93, P<0.01). Similar %N and latitude of origin correlations were observed in another year at this site and in retrospective analyses of published data for different sets of Scots Pine populations grown in common gardens at 48°, 52 °C and 62 °N latitudes. Needle R d rates of the 11 lowland populations growing at Kornik and measured at a common temperature (20 °C) were greater, by as much as 50%, for more northerly than southerly populations. Mean R d rates were positively correlated to latitude of origin and to mean annual temperature (P < 0.05, r = 0.7 to 0 8). R d and needle %N were positively correlated (P<0.01, r=0.75), with one relationship fitting all data. Across the entire range from 1.15 to to 1.55 needle %N, R d increased from 4.5 to to 6.9 nmol g -1 s -1 . Mean needle %N and R d values for two montane southern populations (43 ° and 44 °N, elevation ≥ 885 m) growing in the same common garden at Kornik were consistent with the relationships between mean annual temperature, needle %N and R d observed for the more northerly populations but did not fit the latitudinal patterns. This suggests that temperature and/or associated climate variables are likely the driving force for observed genetic variation in Scots Pine needle %N and R d across latitudinal and altitudinal gradients. Results of these common garden studies support the idea of a general relationship between needle dark respiration and N concentration, and indicate that there is intraspecific genetic variation in physiology that is selected by climate that persists in a common environment, resulting in higher needle %N and respiration in plants originating from colder habitats. Such patterns need to be better understood and quantified, and merit consideration in modelling of current and potential global change effects on plant function and global carbon cycles.

Kin Association in the Allodapine Bee Exoneura richardsoni Rayment (Hymenoptera: Apidae)

ABSTRACT Exoneura richardsoni is a common allodapine bee which, in southern montane Victoria, primarily nests in dead fronds of tree ferns. We sampled intact colonies from the Dandenong Ranges from August 1992 through to February 1993. The bee is univoltine, with egg production commencing in later winter and adult eclosion occurring over summer. The majority of colonies in both re‐used and newly founded nests contain more than one female. Intra‐colony relatedness is very high (r =± s.e., 0.759 ± 0.087) in re‐used nests and moderately high (0.498 ± 0.152) in newly cofounded colonies, indicating maintenance of kin integrity during nest re‐use and kin recognition during foundress association. This is only the second time that kin cofounding has been demonstrated in a primitively social bee species. Samples during winter and early summer show that per capifa brood production increases with colony size up to about 3 or 4 females per nest, and this may explain the high degree of social nesting in this species. Whilst eusociality could occur in some nests, the opportunities for older, adult brood members to help rear younger siblings are very limited. It seems likely that in E. richardsoni and at least some other Australian allodapine bees, the selective maintenance of high levels of social nesting and kin recognition does not depend on the existence of eusociality.