The revegetation of islands following retreat of Pleistocene glaciers is of great biogeographical interest. The San Juan Islands, Washington, feature regionally distinctive xerophytic plant communities, yet their vegetation history, as it relates to past climate and sea level, is poorly known. We describe a 13,700-year-old pollen record from Killebrew Lake Fen and compare the vegetation reconstruction with others from the region. The data suggest that the narrow channels surrounding Orcas Island were not a barrier to early postglacial immigration of plants. Between 13,700 and 12,000 cal yr BP, Pinus, Tsuga, Picea, Alnus viridis, and possibly Juniperus maritima were present in a mosaic that supported Bison antiquus and Megalonyx. The rise of Alnus rubra-type pollen and Pteridium spores at ca. 12,000 cal yr BP suggests a warming trend and probably more fires. Temperate conifer taxa, including Cupressaceae, Pseudotsuga, Tsuga heterophylla, and Abies, increased after 11,000 cal yr BP and especially in the last 7000 cal yr BP. After 6000 cal yr BP, Pseudotsuga and Cupressaceae dominated the vegetation. The last 1500 yr were the wettest period of the record. Due to its rain shadow location, Orcas Island experienced drier conditions than on the mainland during most of the postglacial period.

The study of altitudinal gradients has made enduring contributions to the theoretical and empirical bases of modern biology. Unfortunately, the persistence of these systems and the species that compose them is threatened by land-use change at lower altitudes and by climate change throughout the gradients, but especially at higher altitudes. In this review, we focus on two broad themes that are inspired by altitudinal variation in tropical montane regions: (1) dimensions of biodiversity and (2) metacommunity structure. Species richness generally decreased with increasing altitude, although not always in a linear fashion. Mid-altitudinal peaks in richness were less common than monotonic declines, and altitudinal increases in richness were restricted to amphibian faunas. Moreover, gradients of biodiversity differed among dimensions (taxonomic, phylogenetic and functional) as well as among faunas (bats, rodents, birds) in the tropical Andes, suggesting that species richness is not a good surrogate for dimensions that reflect differences in the function or evolutionary history of species. Tropical montane metacommunities evinced a variety of structures, including nested (bats), Clementsian (rodents, bats, gastropods), quasi-Clementsian (reptiles, amphibians, passerines) and quasi-Gleasonian (gastropods) patterns. Nonetheless, compositional changes were always associated with the ecotones between rain forest and cloud forest, regardless of fauna.

The Azorean seabed is depauperate in terms of bivalve species richness, there being only between ~70 and 80 recorded to date, most being sub-tidal and generally lacking of specialists. Analysis of large numbers (>3200) of Azorean bivalve shells has revealed that, overall, each species is only ~50% the shell length size of Mediterranean conspecifics. Thus, although Azorean bivalve size may be a consequence of decreasing latitude (Bergmann's Rule), the islands are located at approximately the same latitude as the Mediterranean (and are influenced by those waters) where larger conspecifics occur. Hence, the main reason for bivalve dwarfism in the archipelago appears to result from low oceanic productivity (Foster's Rule). This, in turn, is associated with low diversity, possibly resulting from past extinctions and isolation, and low population sizes, except for Ervilia castanea, which here overwhelmingly occupies higher-energy inshore habitats and associated higher productivities. Nevertheless, this species too is dwarfed by mainland conspecifics. Similarly, the introduced Venerupis decussata, found solely within the lagoonal environment of Fajã de Santo Cristo on São Jorge, is somewhat smaller than its mainland conspecifics, although it is abundant enough to warrant artisanal exploitation. This study therefore, supports Foster's Rule and argues for the role of nutrient deficiency in regulating Azorean species richness and individual maximum size. In waters of locally higher productivities, however, population densities increase, but not size.

Studies of recently isolated populations are useful because observed differences can often be attributed to current environmental variation. Two populations of the lizard Anolis lemurinus have been isolated on the islands of Cayo Menor and Cayo Mayor in the Cayos Cochinos Archipelago of Honduras for less than 15 000 y. We measured 12 morphometric and 10 habitat-use variables on 220 lizards across these islands in 2 y, 2008 and 2009. The goals of our study were (1) to explore patterns of sexual dimorphism, and (2) to test the hypothesis that differences in environment among islands may have driven divergence in morphology and habitat use despite genetic homogeneity among populations. Although we found no differences among sexes in habitat use, males had narrower pelvic girdles and longer toe pads on both islands. Between islands, males differed in morphology, but neither males nor females differed in habitat use. Our data suggest that either recent selection has operated differentially on males despite low genetic differentiation, or that they display phenotypic plasticity in response to environmental variation. We suggest that patterns may be driven by variation in intrapopulation density or differences in predator diversity among islands.

Based on the distribution, molecular similarity and use of Morinda citrifolia L., and occurrence of a wild Morinda species, Southeast Asia and Micronesia have been suggested to be the places where noni originated. The present article discusses the indices used by Vavilov and subsequent authorities on the origin of crop plants to argue that South Asia (Southeast India) has a greater probability of being the centre of domestication/origin for noni than Southeast Asia or Micronesia. The basic reasoning is that economically important plant cannot originate without richness in biodiversity and ingenuity of local people. India with rich floristic diversity, one of the centres of origin of crop plants with a natural distribution of Morinda species, including M. citrifolia L. and its immediate ancestors, has the oldest reference of occurrence, use and cultivation (Vedic literature); therefore, it appears to be the more probable centre of noni's origin. The ancient history of the expansion of Indian culture, religion and trade to Southeast Asian countries corroborate the possible role of Indians in the introduction of noni or knowledge regarding its value to Southeast Asia, from which it was carried to Micronesia and Polynesia, which provided a more favourable environmental niche for perpetuation and use.

The ‘campos de murundus’ (carthmound fields) are typical landscapes of the cerrado (savanna) region of Central Brazil and are characterized by many rounded earthmounds called ‘murundus’ which are scattered over a grassland surface. As these areas are normally liable to seasonal water-logging, the earthmounds are true habitat islands capable of bearing woody plants typical of the cerrado, which are normally very intolerant of root inundation. The vegetation of an area of murundus field at Cuiaba, in the State of Mato Grosso, Central Brazil, was surveyed for the purpose of evaluating the island-effect on the plant community growing on the mounds/islands. Two main aspects were considered: the influence of the size of the mound and the differences between the types of cerrado occurring on the mounds and on the areas surrounding the murundus field. Most plant species occurring on the mounds were also present in the flora of the surrounding cerrado. However, only a fraction of these species was able to colonize the mounds successfully. The number of species on the mounds was found to be significantly correlated with mound area. Speciesarea relationships were better described with the power model S = C(Az) than with the exponential model S = C + z (logA) (fitted with linear regression). The mound size also had a strong influence on the spatial distribution of the species on the surface of the mounds. The species were organized in an increasing number of concentric topographic belts corresponding to a gradient of soil depth above the Hooding level.

Trapping and netting of small mammals on a land-bridge island (Leyte) and on an oceanic island (Negros) revealed similar patterns of elevational change in abundance and species richness. Fruit bats (Pteropodidae) reached their greatest local densities in agricultural areas, and were least abundant in montane mossy forest. The fruit bats found to be common in agri-cultural areas are widespread in Southeast Asia: in contrast, species that were most common in forested areas are Philippine endemics. Fruit bat abundance was greater on the oceanic island than on the land-bridge island. Trappable small mammals (families Soricidae and Muridae) showed no change in species richness with increasing elevation, but did show a gradual increase in overall abundance. Even though the oceanic island was depauperate of non-volant mammal species, it had the higher abundance of non-volant mammal individuals; however, this may have been due primarily to differences associated with the elevation of sampling sites. Murid rodents at the higher elevations on Leyte tend to be those that are members of the old endemic group of Philippine murids, and those at lower elevations tend to be members of more recently arrived groups. Most non-volant small mammals at all elevations on the oceanic Negros, and in agri-cultural areas on Leyte, are non-native species.

The investigation of Price & Clancy (1983), which demonstrated a significant positive correlation between total helminth species number per host species and geographical range of freshwater fish host species in Britain, was re-examined using a different measure of parasite species richness. Re-calculation of the correlations between the two parameters after controlling for the effect of the composition of the list of fish by excluding, on biological and distributional grounds, 2 species of agnathans and 7 species of introduced teleosts, and for the effect of sampling effort by using helminth richness in the richest component community of each fish species rather than check-list data, reveals no significant relationship between helminth species richness and host range. Habitat and an omnivorous host diet now appear more significant determinants of helminth richness than the accumulation of parasites by predation. The findings provide little support for the interpretation of the relationship between helminth species richness and host range in terms of island biogeographic theory, but do support an alternative explanation in terms of the colonization time hypothesis, i.e. that helminth species richness is related to the time since the fish host arrived in Britain.

Urgent threats to the Gulf of California ecosystem from modern human activity obscure the fact that humans have interacted with native plants and animals for millennia. Archaeological and historical evidence suggests that indigenous peoples occupied both sides of the Gulf some 13 000 calendar years ago and that they eventually inhabited six major islands and visited most smaller ones. Biologists have increasingly realized that these peoples probably played a role in shaping island biotic communities extant today. How much of a role is unknown, but the best places to find evidence may be archaeological sites, which often contain remains of plants and animals directly used by prehistoric peoples. The opportunity to investigate the interaction between early humans and island biota may be lost because modern island visitors endanger sites. Many people, whether boaters, ecotourists, government officials, scientists or artefact collectors, enjoy picking up artefacts. Small surface sites, with exposed remains, can be completely denuded in minutes. Visitors to small islands can obliterate entire archaeological records, thereby creating the illusion of pristine islands. This problem is bound to worsen as Mexico implements Escalera Náutica, a chain of marinas specifically intended to multiply manyfold the boating population. The Mexican government's management plan for Gulf islands, published in 2000, recognizes only a general need to manage cultural resources. Specific mechanisms for protecting sites should be developed. These should educate visitors about the importance of the archaeological record and the destructiveness of collecting. They should also provide adequate enforcement of Mexico's existing antiquities laws. Conserving the archaeological resources may be the best way of preserving biological data essential to island biogeographers and ecologists.

The potential role of predation as a factor underlying variation in leaf-cutter ant (Atta sp.) densities was investigated on recently isolated land-bridge islands in Lago Guri, Venezuela. A survey of mature Atta colonies revealed a sharp increase in densities on small and medium islands (5.6 and 2.3 colonies ha−1 respectively) compared to large islands (0.72 colonies ha−1) and the mainland (0 nests in 5.5 ha). Incipient colonies showed the reverse trend with higher densities on larger landmasses. Cage experiments were conducted to test the impacts of predation on the survival of incipient and young Atta colonies. Protection by wire-mesh cages increased the survival of both incipient and young colonies at all sites. The survival of unprotected incipient and young colonies was significantly reduced on larger landmasses relative to small islands. These results are consistent with burrow survey data that provided indirect evidence of higher armadillo densities on larger landmasses. Findings suggest that reduced predation is a potentially important factor underlying observed variation in Atta density patterns in the Guri islands.