Conservation genetics and ecology of an endemic montane palm on Lord Howe Island and its potential for resilience

Lepidorrhachis mooreana (Arecaceae) is a monotypic palm genus endemic to the remote Lord Howe Island where it is restricted to a small area of cloud forest above 750 m that is likely to be vulnerable to climate change. We investigated genetic diversity and key demographic parameters to assess the palm’s potential long term viability including possible climate change impacts. The palm was found on only one of the island’s two mountain summits, where the sampled sites were effectively behaving as one panmictic population. The moderate genetic diversity found indicates some adaptive potential for L. mooreana. The population was effectively inbred. Large numbers of fruit are produced, but successful juvenile recruitment is limited by predation by introduced rats. The relatively large population size increases the potential for selection for adaptation to a changing climate.     

Elephant herbivory of knob-thorn (Senegalia nigrescens) and ivory palm (Hyphaene petersiana) in Bwabwata National Park,Caprivi, Namibia: The role of ivory palm as a biotic refuge

African elephants have major impacts on vegetation, particularly at high densities. Knob-thorns (Senegalia nigrescens) are typically ring-barked by elephant, and high levels of mortality are common at high elephant densities. Our study aimed to test whether ivory palm clusters (Hyphaene petersiana) form a biotic refuge for knob-thorn against elephant herbivory. We measured the density, damage and mortality of knob-thorns in sites differing according to ivory palm presence and elephant density, and thus, the probability of knob-thorn encounter by elephants. The site with palms and low elephant density, had a high density of knob-thorns, but lower proportions of damaged and dead trees, than sites without palms but with similar or higher elephant density. In the former, knob-thorns were associated with palm clusters, particularly saplings and young adults. In this site, low proportions of damaged and dead knob-thorns were recorded in palm clusters, compared with outside clusters, and to those in the other sites. Our study also showed that juvenile palms which protected knob-thorns, suffered low mortality in contrast to subadult palms. We have no evidence but implicate elephants and suggest that in palm clusters, subadult palms are more accessible to elephants than knob-thorns because of the different methods of utilisation.     

Edge Effects and Seedling Bank Depletion: The Role Played by the Early Successional Palm Attalea oleifera (Arecaceae) in the Atlantic Forest

In this study, we examined the impacts of Attalea oleifera on the structure of seedling bank and discuss potential mechanisms of palm influence. Seed rain, seedling bank, and palm leaf fall were assessed beneath the canopy and in the vicinity of 16 adult palms across the edges of a large fragment (3500 ha) of the Atlantic forest. Moreover, we examined A. oleifera impacts on seed germination and seedling mortality by experimentally submitting seeds and seedlings to prolonged palm-leaf covering. As expected, seedling bank beneath the adults exhibited reduced abundance and species richness at local and habitat scale. Small to large seeds (3.1–30 mm) were underrepresented in the seed rain below adults palms, while experimental leaf covering drastically reduced both seed germination and seedling survivorship. A. oleifera leaf fall occurred over the whole year (3.6±2.7 leaves/individual/yr), which resulted in deep leaf litter mounds (10.7±9.2 cm). Finally, adult palm density (21.6±11.9 individuals/ha) correlated negatively with seedling density across Attalea clusters. Our results suggest that A. oleifera exerts negative effects on the seedling bank by reducing seedling abundance and richness as a consequence of two complementary mechanisms: impoverished and size-biased seed rain plus reduced seed germination and increased seedling mortality due to prolonged covering by fallen leaves.     

Morphological and ecological shifts in a land snail caused by the impact of an introduced predator

Introduced predators have become major threats to native animal species in oceanic islands. A number of studies have shown that alien predators have caused serious extinctions of island endemics. However, little attention has been paid to the evolutionary impacts of alien predators on native species. The present study shows that predation by black rats, Rattus rattus, has resulted in ecological and morphological changes in the land snail Mandarina anijimana from the island of Anijima in the Ogasawara archipelago. The frequency of empty predated shells has increased over the past 17–19 years in southern areas of the island. The shells of these snails were found to be significantly higher, smaller and darker in the survey in 2006 than in the survey in 1987–1989 performed in central and southern parts of Anijima, where predation by Rattus was serious. M. anijimana were formerly restricted to shallow broad-leaved litter, whereas they are currently found in deep palm litter, where predation pressure from Rattus may be lower. This suggests that increased predation pressure by Rattus has changed the habitat use of M. anijimana. The close association between shell morphology and habitat use of Mandarina species suggests that the habitat shift induced by the predation of Rattus has caused these changes in the shell morphology of M. anijimana over a period of 17–19 years.     

Endemism and conservation of Amazon palms

Endemicity is important for the delimitation of conservation areas. Endemic areas are those that contain two or more taxa with their distribution restricted to the area. The aim of this study was to detect endemic areas for palms in the Amazon region and to determine whether the species that define these endemic areas are protected within conservation units. Records of occurrence were extracted from the global biodiversity information facility (GBIF). The final dataset consisted of 17,310 records, for 177 species of Amazonian palms. For analysis we used parsimony analysis of endemicity (PAE) and NDM-VNDM program, and grid square size of 1° and 3° as operational geographic units (OGUs). The distribution of endemic species was superimposed on occurrence of the conservation units (CUs). PAE did not show endemic areas in grid squares of 1°, but found 10 palm endemic areas in grid squares of 3° in the western Amazon and Andean sub-region. However, the NDM-VNDM program identified an endemic area in grid squares of 1° located at the eastern Guiana with endemicity score = 2.9, and in grid squares of 3° it identified seven consensus areas with endemicity score > 6.0, all in the western Amazon. The combination of PAE and NDM-VNDM analyses resulted in eight endemic palm areas in the combined western Amazon and Andean sub-region. Of the species that define the endemic areas, five are threatened with extinction in one of three IUCN categories (EN, VU, NT), and they are not protected in any conservation units. The western Amazon, besides having high palm richness, also has palm endemic areas, especially, near the Andean sub-region and the Peruvian Amazon.     

Fuelling the biodiversity crisis: species loss of ground-dwelling forest ants in oil palm plantations in Sabah,Malaysia (Borneo)

Oil palm plantations today cover large areas of former tropical lowland rain forest in Southeast Asia and are rapidly expanding on the island of Borneo. Study of the community of ground-dwelling ants in different plantations in Sabah, Malaysia, over 2 years using tuna baiting, revealed that the oil palm plantation ground ant community was severely reduced in species richness in comparison to the forest interior, regardless of age, undergrowth cover, or proximity to neighbouring forest. The results indicate that oil palm plantation habitats, now covering more than 15% of Sabah’s land area, can sustain only about 5% of the ground-dwelling ant species of the forest interior. Nine of the 23 ant species baited in the plantations were never recorded inside forest. All numerically dominant ants were non-forest species. The most common species was Anoplolepis gracilipes, an invasive species present at 70% of all bait sites and known to cause ‘ecological meltdowns’ in other situations. The low frequency and species number of forest ground ants indicates that oil palm plantations act as effective dispersal barriers leading to community isolation in rain forest remnants. The replacement of natural forests with oil palm plantations poses a serious threat to the conservation of biodiversity on Borneo if similar results are confirmed in other taxa.     

The biogeographical distribution of microfungi associated with three palm species from tropical and temperate habitats

The microfungi of three palm species were investigated in their natural habitats and in habitats where the palms were cultivated outside their natural ranges. The palms that were selected differed in their habitats and ecology. Archontophoenix alexandrae is endemic to tropical rainforests in Australia, Cocos nucifera is pan‐tropical and Trachycarpus fortunei occurs in warm‐temperate China. Different assemblages of fungi were found in association with palms in temperate regions as compared to those in tropical regions. These differences were more related to climatic influences than to the hosts sampled, as few fungi were host‐species specific. The status of the hosts at the site, i.e. indigenous or introduced, and the degree of disturbance of the habitats within which the palms grew were also influential. When sampled in its natural habitat, Archontophoenix alexandrae had a distinct palmicolous mycota typical of other palms in tropical rainforests. Outside of the palm’s natural habitat, a widely different mycota were recorded that comprised tropical species of a more plurivorous nature. A similar plurivorous assemblage characterized the fungi associated with Cocos nucifera, probably due to the palm’s long history of cultivation. Similarly, plurivorous, but temperate or widespread fungi were associated with Trachycarpus fortunei, both within and outside of its natural habitat. This palm is also highly cultivated. A reduction in palm fungi associated with palms in disturbed habitats has implications for conservation of these fungi. However, it is acknowledged that the data for fungal diversity and distribution is incomplete and fragmentary.     

A pleasing consequence of Norway rat eradication: two shrew species recover

Four to 10 years after the successful eradication of the Norway rat (Rattus norvegicus) from three islands of the Sept–Îles Archipelago and one in the Molène Archipelago (Brittany, France), the abundance index of the lesser white‐toothed shrew (Crocidura suaveolens) increased by factors of 7–25, depending on the island and the year. Moreover, in the same region, the abundance index of the greater white‐toothed shrew (Crocidura russula) on Tomé Island increased by factors of 9 and 17, one and two years after the Norway rat eradication, respectively. The maximum variation of the abundance index for the lesser white‐toothed shrew during seven years on the rat‐free island of Béniguet in the same region was a factor of only 2.5. Moreover, the distribution of the lesser white‐toothed shrew on Bono island, restricted before the eradication to two steep areas with few rats, increased and encompassed virtually the entire island four years after rats disappeared. These results suggest strong detrimental interactions between the introduced Norway rat and the two Crocidura shrew species on temperate oceanic islands. However, our data do not indicate the ecological mechanisms at work in these interactions. The main reason this shrew recovery was detected after rat eradication was the inclusion in the eradication protocol of the evaluation of impacts on the local biota of eliminating alien species. The rigor of the sampling procedure was also crucial to this discovery. This example demonstrates that an eradication operation can be extremely useful for both scientists and managers if it is planned as a research project.     

Molecular genetic analysis of two native desert palm genera,Washingtonia and Brahea,from the Baja California Peninsula and Guadalupe Island

The complex geological and ecological processes that have generated high levels of biodiversity and endemism in the Baja California Peninsula have been the subject of intensive study. However, relatively little is known about phylogeography of the iconic endemic palm species of this region. We therefore analyzed a total of 2,294 bp of chloroplast and 738 bp of nuclear sequence data in 169 samples of five native palm species from Baja California, Sonora and Guadalupe Island. We found that Washingtonia and Brahea palms had low levels of genetic diversity and were highly structured, with the majority of species and major geographic regions being characterized by distinct haplotypes. We also found strong support for currently recognized species in Washingtonia, but our results were less clear cut for Brahea due to haplotype sharing. Furthermore, patterns of population structure were broadly consistent with historical vicariant events such as the inundation of the Isthmus of La Paz, the formation of the Sea of Cortez, and the more recent colonization and isolation of Guadalupe Island's palms. Our findings contribute toward a growing appreciation of the complexity of plant responses to past geological changes and also provide valuable baseline genetic data on relict American palm species.     

Chemical ecology of Cyclocephala forsteri (Melolonthidae), a threat to macauba oil palm cultivars (Acrocomia aculeata,Arecaceae)

The environmental unsustainability of African oil palm crops is a growing worldwide concern, and the macauba palm in tropical Southern America surges as the most viable substitute for the production of first-generation biodiesel as a renewable fuel. Large-scale cultivation of the macauba palm, however, is bound to suffer a major setback due to the fast emergence of a florivorous pest threat, Cyclocephala forsteri, a scarab beetle species that can severely reduce fruit yield. Like other congenerics, female and male C. forsteri are night-foraging and driven in large numbers to macauba palm inflorescences by specific volatile organic compounds. In the present study, we assessed the kairomonal cues involved in this plant–florivore interaction and their potential application in selective pest management strategies. Headspace samples of the floral fragrance of macauba palms at our study site in Central Brazil were largely dominated by 4-methylanisole (>97% relative amount), which along with the minor constituents 2-isopropyl-3-methoxypyrazine and 2-sec-butyl-3-methoxypyrazine triggered electroantennographic responses from both female and male C. forsteri. Field behavioural assays evidenced that beetles of this species were exclusively attracted to scented traps baited with 4-methylanisole. Increased total scent discharge attained with an ultrasonic piezoelectric diffuser has positively influenced attractiveness efficiency of the trapping setup. 4-Methylanisole is hereby identified as yet another volatile kairomone involved in highly selective attraction of potential pest florivorous cyclocephaline scarabs associated with economically exploitable palms and should be viewed as a key element in short-term integrated management plans for the cultivation of the macauba palm in South America.     

Ecology and Management of Nesting Blue-and-Yellow Macaws (Ara ararauna) in Mauritia Palm Swamps

This paper reports on the nesting ecology of blue-and-yellow macaws (Ara ararauna) and the structure, conservation, and management of the Mauritia flexuosa palm swamps where they nest: clutch size averaged 2.6 and the number of chicks fledged per nesting attempt was 0.5. Macaws nested in tall dead palms in healthy palm swamps and in palms of all heights in open dieing palm stands. All nesting palms rose well above the surrounding vegetation presumably to discourage terrestrial predators. PVC nest boxes failed to attract nesting blue-and-yellow macaws. A small section of palm swamp was managed to encourage macaw nesting by cutting the tops off of M. flexuosa palms and clearing the understory vegetation. The palms remained standing from 4 to 7 years and were occupied by nesting macaws at a rate of 24%. The data presented here suggest that cutting five palms a year in perpetuity would produce a stand of approximately 20 standing dead palms used by 6 or more pairs of macaws annually. However, macaw occupancy rates would depend on the density of macaws and density of naturally occurring nest sites. This management scheme could be conducted on a 100-year rotation in an area of 1–4 ha or more depending on the palm density. Such a colony could be used to increase reproductive success of blue-and-yellow macaw populations, create a valuable ecotourism resource, and concentrate macaw nesting in protected areas.     

The complex colonization history of nocturnal geckos (Paroedura) in the Comoros Archipelago

Hawlitschek, O. & Glaw, F. (2012). The complex colonization history of nocturnal geckos (Paroedura) in the Comoros Archipelago. —Zoologica Scripta, 00, 000–000. Oceanic islands have attracted special attention from evolutionary biologists because their mostly species‐poor, but highly endemic biota are exposed to selection regimes different to those of their mainland relatives. While many groups of oceanic islands worldwide have been used as natural laboratories of evolutionary biology, few such studies have been performed on the Comoros Archipelago in the Western Indian Ocean. We study Paroedura sanctijohannis Günther 1879, a nocturnal gecko endemic to this archipelago as only species of an otherwise Malagasy endemic genus. According to our phylogeny, P. sanctijohannis is not monophyletic, the population of the geologically oldest island Mayotte is clustering with related Malagasy species. We describe this population as Paroedura stellata sp.n. and provide morphological evidence distinguishing it from other Paroedura species. A molecular clock analysis shows that genetic divergence within P. sanctijohannis of the youngest island Grand Comoro is higher than expected based on its geological age. Additionally, this population is paraphyletic with respect to the population of the older island Anjouan, suggesting that the latter island was colonized long after its initial emergence, possibly after extinction of an original Paroedura population. Furthermore, we find that P. stellata sp.n. and P. sanctijohannis are more similar to each other than to other Paroedura species regarding adult coloration and juvenile coloration. Because these two species are not each other’s closest relatives, we discuss possible explanations for this pattern and suggest that it represents convergent adaptation to a relaxed insular selection regime.     

The impacts of rats on the endangered native flora of French Polynesia (Pacific Islands): drivers of plant extinction or coup de grâce species?

Although rats have clearly contributed to bird extinctions on islands, their role in plant extinctions is not as clear. Paleoenvironmental studies suggest rats were responsible for the demise of several island palm species. French Polynesia’s islands provide an opportunity to evaluate “modern” impacts of rats on native flora. Our study shows that 15 threatened taxa (nine families) are damaged by rats. All 12 subjected to seed predation are woody plants with large-seeded drupes. Three experience severe predation and recruitment depression (Santalum insulare, Ochrosia tahitensis, Nesoluma nadeaudii). Three-year monitoring of Polynesian sandalwood (Santalum insulare) populations in Tahiti during rat control suggested that over 99% of fruits were eaten before ripening. Seed predation on sandalwood appeared to be lower on islands without black rats Rattus rattus. Studies from Indo-Pacific islands document rat impact on at least 56 taxa (28 families). Certain families (Arecaceae, Elaeocarpaceae, Rubiaceae, Santalaceae, and Sapotaceae) are particularly vulnerable to seed predation. Other soft-barked trees (Araliaceae, Euphorbiaceae, and Malvaceae) suffer from stem or bark damages, especially during dry seasons. Although rats depress seedling recruitment and alter vegetation dynamics, no evidence demonstrates that they are solely responsible for current plant extinctions. Most of French Polynesia’s endangered species impacted by rats occur in severely degraded habitats. We therefore suggest that rats can be viewed more as coup de grace species (i.e., that give the final stroke of death), rather than as main drivers of plant extinctions. More research is needed to clarify the impacts of rat species and their importance in plant population decline or demise.     

Predators and competitors of the mountain pine beetle Dendroctonus ponderosae (Coleoptera: Curculionidae) in stands of changing forest composition associated with elevation

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Association of Copper and Zinc Levels in Oil Palm (Elaeis guineensis) to the Spatial Distribution of Ganoderma Species in the Plantations on Peat

Nutrients are essential for normal physiological processes in plants, and they play important roles in defence mechanisms against pathogens. Oil palms cultivated on peat are more prone to nutrient deficiency, especially micronutrients, and this may affect their susceptibility to Ganoderma species, the major threat to the sustainability of oil palm throughout South‐East Asia. This study was conducted to investigate the association of copper (Cu) and zinc (Zn) in mature oil palm to the spatial distribution of Ganoderma species in the plantations on peat. Foliar samples (frond 17) of oil palm from two plantations (Betong and Miri) on peat in Sarawak, Malaysia, were collected based on the spatial distribution pattern of Ganoderma, and total Cu and Zn were quantified spectrometrically. The experiment was conducted twice at a 1‐year interval. The concentrations of Cu and Zn were significantly lower in oil palms from infected areas in contrast to those from uninfected areas. In addition, oil palms in infected areas in Miri suffered Cu and Zn deficiencies. Furthermore, Cu and Zn were significantly lower in the oil palms in Miri that had higher Ganoderma occurrence, as compared to those in Betong, which had significantly higher Cu and Zn but lower Ganoderma occurrence.     

Two fungi associated with necrotic leaflets of areca palms (Areca catechu)

Information on fungi associated with necrotic leaflets of exotic palms in Thailand is scanty, as previous studies were mainly focused on decaying fronds. This study provides some information regarding fungi associated with necrotic leaflets of exotic palms in Thailand. Specimens in this work were collected from several locations in Chiang Mai province, including natural and planted areas. One new species, Cercospora arecacearum on areca palm (Areca catechu), is described and illustrated. An ITS sequence data analysis confirms the separation of the new Cercospora species from related taxa. Another species, Neorehmia arecae, hitherto only known from areca palm, is newly recorded for Thailand. Furthermore, Wallichia siamensis is a new host for this species.     

Parrots consume sodium‐rich palms in the sodium‐deprived landscape of the Western Amazon Basin

Herbivorous animals face shortages of different minerals in different geographic areas. In the Amazon Basin, sodium is often limiting, driving herbivores to seek supplemental sources. In the lowlands of the western Amazon Basin, parrots commonly consume sodium‐rich soils at clay licks but lick use varies widely among species, and to date, parrots in the region have not been reported consuming other supplemental sodium sources. We document 11 species of psittacines consuming sodium‐rich leaves and trunks of Attalea butyracea palms growing on sodium‐rich soils in lowland Peru. Consumed palms had more sodium and less potassium than uneaten A. butyracea palms and other palm species in the area. Among A. butyracea palm parts, sodium and Na:K ratios were highest in trunks (consumed by parrots in 94% of the 387 foraging bouts recorded) and lowest in leaves (consumed in only 14% of foraging bouts). The low potassium and high Na:K ratio suggest that birds may be seeking not just any sodium sources, but those low in potassium, as potassium is known to exacerbate dietary sodium shortages. Use of the palms and species’ abundance in the study area were not correlated. Instead, parrot species that consumed palms the most were those that use relatively few traditional soil clay licks. This finding suggests that parrot species in the region have fundamental differences in preferred strategies for obtaining supplemental sodium and may help explain documented interspecific differences in geophagy.     

Bats of the Gulf of Guinea islands: faunal composition and origins

The present study compares the bat faunas of the islands of the Gulf of Guinea. Species composition. endemism and hypothetical origins are discussed. All families present in the mainland region are found in Bioko, a typical landbridge island. Foliage gleaning guild species (Nycteridae) show limited colonization abilities. This is also true of the family Rhinolophidae, but not for the closely related family Hipposideridae. The majority of the oceanic island species are African bats which show a widespread distribution and, therefore, have a high ecological plasticity. The continental relatives of the two endemic species Myonycteris brachycephala and Chaerephon tomensis are restricted to relatively small forested areas. Bioko's bat fauna is the result of the recent isolation from a formerly land-connected community. The oceanic bat faunas originated from the establishment of incomers from other areas. Nevertheless, extinction appears in both vicariant and dispersal processes, as an important factor in modelling the current bat communities of the Gulf of Guinea islands.     

Increasing distribution and damage to palms by the Neotropical whitefly,Aleurotrachelus atratus (Hemiptera: Aleyrodidae)

In recent years, the coconut whitefly, Aleurotrachelus atratus Hempel, has been recorded from various islands in the southwestern Indian Ocean. Field surveys in La Réunion, the Seychelles, the Comoros and glasshouses in Paris have allowed us to record this whitefly on 56 palm species, some of which are endemic and/or threatened species. Most of trees showed low infestation levels, except for the coconut palm that is its main host plant. Such a wide host range has facilitated the rapid geographical dissemination of this whitefly. A field study was conducted in 2006 in La Réunion, to gain a better understanding of the bioecology of A. atratus in a tropical insular ecosystem. The whitefly was found throughout the island, from sea level to 800‐m altitude. Five parasitoid species (Hymenoptera: Aphelinidae) were found associated with the populations of this pest, with Eretmocerus cocois Delvare being the dominant one. A laboratory study showed that the pre‐imaginal development of A. atratus is around 48 days at 25–27°C, which is relatively long compared to other whitefly species. With a sex ratio of one male per 1022 females collected in La Réunion, it appears that the whitefly reproduces by thelytoky. It represents a threat to ornamental and agricultural palms as well as to natural palm ecosystems in the absence of effective parasitoids.     

Plant Invasions on an Oceanic Archipelago

Plant invasions are particularly noticeable on oceanic islands. For many ecological or evolutionary phenomena, oceanic islands offer advantages in comparison to continental regions, because they are often simpler systems. The Juan Fernández (Robinson Crusoe) Islands, located 667 km west of continental Chile, provide an especially favorable case study of plant invasions on an oceanic archipelago. They have little flora, no influence from aboriginal peoples, and good historical and recent documentation of flora, vegetation and human impacts. The total flora of the archipelago consists of 441 vascular plants, of which 209 are native (125 of them endemic) and 232 are aliens. Many alien species exist on the Juan Fernández Archipelago, but three shrubs are particularly invasive: Aristotelia chilensis, Rubus ulmifolius, and Ugni molinae. About 15% of the total area of the island has been impacted by at least one of these shrubs. In addition, the herbaceous Acaena argentea, now occurs at high abundance in 12% of the total area of the island. Comparisons of earlier and recent surveys of vegetation reveal that the area impacted by Aristotelia, Rubus, and Ugni molinae has increased tremendously. Among the most frequent aliens are Euro-Mediterranean taxa, also present on other archipelagos. A few aliens that are serious invasives on other archipelagos have been recently observed near San Juan Bautisata, the only village on the island. Effective measures involving stronger monitoring and sanitation of incoming materials (foodstuffs, building materials, etc.), cutting or poisoning of invasives, and reseeding with native species, are necessary to help preserve the native and endemic flora (and biota) of these islands.