Ecological factors affecting gene flow between populations of Anarthrophyllum cumingii (Papilionaceae) growing on equatorial- and polar-facing slopes in the Andes of Central Chile

In the Andes of Central Chile, flowering commences 1–2 months earlier on equatorial-(north-) facing than on polar- (south-) facing slopes, and pollinator assemblages also differ between these habitats. In order to understand the potential influence of these differences on gene flow, we monitored flowering periods and insect visitation rates to flowers of 60 individuals of Anarthrophyllum cumingii (Papilionaceae) on two equatorial- and two polar-facing slopes in the Andes of central Chile (33°35 S;70°32 W). Flowering began about 30 days earlier on equatorial-facing slopes. Flowering periods of individuals on slopes with the same aspect had a mean overlap of 0.52, while those on opposite slopes had a mean overlap of 0.15. On equatorial-facing slopes Yramea lathionoides (Lepidoptera) accounted for 60% of the visits to flowers of A. cumingii, while on polar-facing slopes Centris cineraria (Hymenoptera) was responsible for more than 80% of flower visits. Average similarities of visitor assemblages among individual plants on slopes with the same aspect was 0.83, while the mean similarity between individuals on opposite slopes was only 0.23. Within slopes fluorescent dyes were dispersed up to 40 m from the donor plants, but there was no movements of dyes between individuals growing on opposite slopes, even when they were separated by less than 10 m. Synchronous blooming and a common pollen vector are necessary conditions for pollen exchange between individuals. The overall probability of pollen exchange estimated by multiplying the inter-individual overlap for both factors, was nearly 0.5 for individuals growing on slopes with the same aspect, and less than 0.04 for individuals growing on opposite slopes. Consequently, at equivalent distances, the probability of pollen exchange between individuals growing on slopes of opposite aspect is more than 10-times lower than between those growing on the same slopes. Seed dispersal cannot compensate for restricted gene flow through pollination, because seeds of A. cumingii were dispersed less than 2 m away from a parent plant. Presumably, restricted gene flow could enhance genetic divergence between populations on slopes of contrasting aspects. This factor could be important in contributing to the high diversity and endemism in the Chilean Andes.     

Phylogeography and genetic effects of habitat fragmentation on endangered Taxus yunnanensis in southwest China as revealed by microsatellite data

It is not known how the profoundly complex topography and habitat heterogeneity generated by the uplift of the Qinghai‐Tibetan Plateau (QTP) during the late Tertiary affected population genetic structure of endangered Taxus yunnanensis. In addition, the effects of habitat fragmentation due to anthropogenic disturbance on genetic diversity and population differentiation of this species have not been studied. T. yunnanensis is an ancient tree/shrub mainly distributed in southwest China. Recently, the species has suffered a sharp decline due to excessive logging for its famous anticancer metabolite taxol, resulting in smaller and more isolated populations. To understand the phylogeography and genetic consequences of habitat fragmentation of this endangered species, using 11 polymorphic microsatellites, we genotyped 288 individuals from 14 populations from a range‐wide sampling in China. Our results suggest that two different population groups that were once isolated have persisted in situ during glacial periods in both areas, and have not merged since. Habitat fragmentation has led to significant genetic bottlenecks, high inbreeding and population divergence in this species. The two different population groups of T. yunnanensis could be attributed to restricted gene flow caused through isolation by geographical barriers and by habitat heterogeneity during uplift of the QTP, or the existence of two separate glacial refugia during the Pleistocene. In situ and ex situ conservation of the two Evolutionarily Significant Units (ESUs), artificial gene flow between populations and a comprehensive understanding of the pollination system in this endangered species are suggested from this study.     

Seed plants of Fiji: an ecological analysis

An annotated list of indigenous Fijian seed plant genera is presented and comprises 484 genera and 1315 species in 137 families. The relative diversity of the largest families and genera in Fiji is indicated and compared with floras in New Caledonia and the Upper Watut Valley, Papua New Guinea. Differences and similarities appear to be due to biogeographical/phylogenetic factors rather than ecological differences or means of dispersal. Generic diversity for the seed plants as a whole is greatest between 0–100 m and decreases monotonically with altitude. However, in the largest family, Orchidaceae, maximum diversity occurs between 200–400 m. Fifty percent of the families are recorded from shore habitat. Twenty‐seven percent of the families and 80 species occur in or around mangrove, where the most diverse families are Orchidaceae, Rubiaceae, and the legumes. Some of the mangrove‐associate species are pantropical or Indo‐Pacific but most are locally or regionally endemic. Fifty‐six percent of the Fijian families are recorded on limestone. Twenty‐nine species are restricted to limestone and 12 species usually occur on limestone. The importance of calcium in reducing the effects of salinity is emphasized and 39 species are recorded from both mangrove and limestone. A plagiotropic habit occurs in 38 species which occur on limestone or around beaches, and 20 of these are Pacific endemics. Genera restricted to higher altitudes include many present elsewhere in Melanesia but absent from Australia despite suitable habitat there, again indicating the importance of biogeographical and historical factors. Altitudinal anomalies in Fiji taxa are cited and include 7 anomalously high records from northern Viti Levu, a site of major uplift, and 22 anomalously low altitudinal records in the Lau Group, a site of subsidence. It is suggested that the Fijian flora has not been derived from immigrants from Asia, but has evolved more or less in situ. Taxa would have survived as metapopulations on the individually ephemeral volcanic islands always found at oceanic subduction zones and hot spots, and the atolls which characterize areas of subsidence. The complex geology of Fiji is determined by its position between two subduction zones of opposite polarity, the Vanuatu and Tonga Trenches, in what is currently a region of transform faulting. The large islands comprise fragments of island arcs that have amalgamated and welded together. There has been considerable uplift as well as subsidence in the islands and it is suggested that both these processes have had drastic effects on the altitudinal range of the taxa. Limestone and mangrove floras could have provided a widespread, diverse ancestral species pool from which freshwater swamp forest, lowland rainforest, dry forest, secondary forest, thickets, and montane forest have been derived during phases of uplift. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 89 , 407–431.     

Ultraviolet‐B‐driven pigmentation and genetic diversity of benthic macroinvertebrates from high‐altitude Andean streams

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Periodic anoxia in an emerging coastline lake basin in SW Finland

Inre Verkviken, a fjord-like, 20 m deep inlet in northern Åland, SW Finland, was probably a holomictic brackish-water lake nearly completely isolated from the sea by land uplift (about 0.5 cm yr^–1) before 1929 when a canal was built to the Bothnian Sea. The canal was enlarged in the 1950s and again in 1978, keeping Inre Verkviken brackish (5–6). Inre Verkviken is now (the 1990s) in a phase of periodic meromixis — for the second time in about 100 years — as it undergoes a second process of lake formation due to land uplift. Anoxic conditions often prevail below 10–12 m depth. The summer oxygen conditions are unpredictable as they depend on the spring mixing patterns, which again largely depend on the duration of ice cover, the meteorological conditions, and the timing and quantity of spring runoff.     

Traditional livestock activities modify the spatial behavior of small wildcats in the high Andes

Human activities lead to declines in species’ abundance and diversity, as well as loss of habitat quality from overexploitation. The effects of livestock grazing increase on small felids are poorly understood, primarily due to the low detectability of these species. The grazing of domestic camelids, such as the llama (Lama glama) and the alpaca (Vicugna pacos), is the main traditional source of income for the inhabitants of the Andes, where the Andean cat (Leopardus jacobita) and Pampas cat (L. colocolo) are also present. In this study, we employ camera trap data to evaluate the association of llama and alpaca grazing with occupancy by the Andean and Pampas cat in Sajama National Park. In each of 36 sampling stations, we installed a camera trap, a grid of traps for rodents and two habitat transects along a gradient of intensity of livestock grazing. Occupancy models showed that negative effect of camelid abundance was stronger for the Andean cat than the Pampas cat. For both species, occupancy was also associated positively to the abundance of prey, proximity to water bodies, and vegetation. Given that livestock activity is a way of life for human populations in the Andes, we suggest that mechanisms should be implemented to compensate for the negative effects of livestock on Andean and Pampas cat populations.     

The influence of historical dispersal on the phylogenetic structure of tree communities in the tropical Andes

We test for evidence of the Tropical Niche Conservatism or the Out of The Tropics hypotheses in structuring patterns of tree community composition along a 2000 + meter elevational gradient in the northern tropical Andes. By collecting and integrating data on the presence–absence of tree species within plots with phylogenetic information, we analyzed the following: (a) patterns of phylogenetic dispersion and species diversity along the elevational gradient based on indexes of net relatedness, nearest taxon relatedness, and species richness (α‐diversity); and (b) the replacement of lineages along the gradient using the PhyloSorensen metric (β‐diversity). More specifically, we established 20 0.25‐ha permanent tree inventory plots between 750 and 2,802 m asl where all individuals with diameter at breast height (DBH) ≥ 10 cm were measured and identified. We then used a series of linear models to test for changes in α and β diversity between plots in relation to elevation. Neither the net relatedness index nor the nearest taxon index showed a significant relationship with elevation. However, there was greater phylogenetic overdispersion at intermediate elevations; this likely reflects the mixing of species with contrasting origins from tropical and temperate lineages. β‐diversity between plots was negatively related to the corresponding difference in elevation, indicating that closely related lineages occupy similar ranges of elevation and temperature. We conclude that the immigration of lineages from extra‐tropical regions has significant effects in determining the phylogenetic structure of tree communities in tropical Andean forests. Abstract in Spanish is available with online material.     

Predatory Behavior of the Opossum Didelphis albiventris on the Pitviper Bothrops jararaca

The predatory behavior of Didelphis albiventris (Didelphidae) on Bothrops jararaca (Viperidae) was described from encounters provoked in captivity. One adult and four young opossums presented the same behavior when killing and ingesting the snakes. Opossums subjugated the snakes by biting them in the head or neck region and began ingestion by eating this part first. The total time spent in subjugation plus ingestion was 24:23 min (SD = 8:08 min). Although D. albiventris is resistant to snake venom, the behavioral sequence observed is, probably, not a specialization for snake predation. It probably consists of a general and primitive pattern of prey manipulation observed in carnivorous mammals.     

Nutrients in fruits as determinants of resource tracking by birds

Fruit pulp is an important source of nutrients for many bird species. Fruit‐eating birds use a variety of strategies to cope with changes in the availability of fruits, exhibiting a remarkable ability to track resources. We assessed the role of nutrient availability in the fruiting environment as a factor driving resource tracking by fruit‐eating birds. Fruit consumption by the four most common frugivorous species in a 6‐ha plot in the Southern Yungas montane forest of Argentina was assessed. We determined the content of selected nutrients (soluble carbohydrates, proteins, phenols, ascorbic acid and essential minerals) in 22 fruiting plant species eaten by birds, and measured fruit–frugivore interactions and the availability of nutrients and dry fruit pulp mass over 2 years. There was strong temporal covariation in the availability of the selected nutrients in fruits across the study period. Similarly, the availability of nutrients in the fruiting environment covaried with pulp mass. Fruit consumption by the four commonest bird species and the abundance of most species were positively associated with nutrient availability and dry pulp mass. Nutrient availability was a good predictor of temporal fruit tracking by three of the four commonest frugivores. Despite large differences in particular nutrient concentrations in fruits, overall nutrient (and pulp) quantity in the fruiting environment played a greater role in fruit tracking than did the nutritional quality of individual fruits. While overall nutrient availability (i.e. across fruit) and total pulp mass were important determinants of fruit tracking, we suggest that plant species‐specific differences in fruit nutrient concentration may be important in short‐term foraging decisions involved in fruit choice and nutritional balance of birds.