Insular Floras Research Articles

Opportunistic nectar‐feeding birds are effective pollinators of bird‐flowers from Canary Islands: experimental evidence from Isoplexis canariensis (Scrophulariaceae)

Insular floras, characterized by simple pollination networks, sometimes include novel mutualistic agents such as nonspecialist nectarivores. In this study we confirmed the effective pollination of Isoplexis canariensis by opportunistic nectar-feeding birds in Tenerife, Canary Islands, Spain. This plant is among the ornithophilous species of the Canarian flora that lack past and present specialist nectarivorous birds. Experimental hand pollinations revealed self-compatibility, but cross-pollinated flowers produced a greater percentage of viable seeds than self-pollinated ones. Flowers were visited by five species of birds (Phylloscopus canariensis, Parus caeruleus, Sylvia melanocephala, Serinus canarius, and Fringilla coelebs) and by the endemic lizard (Gallotia galloti, Lacertidae). Insect pollination was absent, and the few insect visitors acted as nectar thieves or secondary nectar robbers. Birds represented 93.1% of total visits, with the Canarian Chiffchaff, Ph. canariensis, being the most frequent visitor. Flowers visited by birds set more, larger, and heavier fruit than flowers from which birds were excluded. Bird visitation also enhanced seed viability. These results demonstrate the active role of these opportunistic birds as effective pollinators of this Canarian bird-flower species. Further, the results reveal the need to consider the effect of these birds on the evolution of ornithophilous floral traits in absence of specialist nectarivores.

Patterns and processes in insular floras affected by hurricanes

AbstractAim To investigate species compositions, rates of species turnover, species–area and species–distance relationships and patterns of nestedness in the floras of small Bahamian islands, by comparing two groups of islands that had been differentially affected by two hurricanes.Location Small islands occurring on either side of Great Exuma near Georgetown, Bahamas.Methods We surveyed the plant species of 44 small islands over a 5‐year period from 1998 to 2002. Hurricanes Lili and Michelle occurred in 1996 and 2001, respectively; both storms affected small islands on the more exposed south‐west side of Great Exuma to a greater degree than small islands on the more protected north‐east side. A set of 27 islands was surveyed in 1998 and 2002 to evaluate species turnover. Stepwise multiple linear regression analyses and an information‐theoretic approach (the Akaike information criterion) were used to elucidate the importance of area and distance as predictors of plant species number. We compared a piecewise linear regression model with a simple linear regression of species number against area to determine whether a small island effect existed. Nestedness patterns were evaluated by Wilcoxon two‐sample tests to analyse occurrence sequences.Results Species turnover was low in an absolute sense (overall = 0.74% year−1), yet was over three times higher than that documented in a nearby archipelago in the absence of hurricanes. Both vegetated area and distance were important predictor variables for exposed islands but not for protected islands. Some support was found for a small island effect for the exposed islands based on a piecewise linear regression model. Both island groups revealed significant nestedness at the level of the assemblage (both P < 0.001). On exposed islands, 65–79% (depending upon the method of calculation) of all species were significantly nested, but only 47% of all species were significantly nested on protected islands.Main conclusions Overall, these insular floras seem highly resistant to hurricane‐force disturbances. Species turnover was low (< 1% year−1) in an absolute sense, particularly in comparison with rates for other taxa. Higher degrees of nestedness and significant species–area and species–distance relationships for exposed islands indicated stronger patterns of community assembly. It is likely that disturbance is a major structuring force for the exposed islands, although the type of disturbances that mediate these patterns may not be primarily hurricane‐force storms.

Verifying an Extinction Debt among Lichens and Fungi in Northern Swedish Boreal Forests

Abstract: Destruction and fragmentation of natural habitats results in small species populations that face increased risk of extinction. A time delay may be involved in the regional extinction of species, and the number of species that eventually may go extinct in the future is called the “extinction debt.” In boreal Sweden, we examined whether the number of epiphytic crustose lichens and wood‐inhabiting fungi in old‐growth forest remnants diverges from species richness levels in forest patches that have been naturally isolated for millennia. An excess of species in forest remnants could indicate the presence of an extinction debt. Observed species richness in 32 old‐growth forest remnants (also called woodland key habitats [WKHs]) was compared with predicted species richness. To predict species richness we used regression models based on data from 46 isolated old‐growth forest patches in a forest‐wetland matrix. The reference landscape is ancient and assumed to reflect the conditions of insular floras in dynamic equilibrium. Stand factors constituted predictive variables in the models. The observed number of lichen species was higher than expected (i.e., an extinction debt among lichens may exist). By contrast, there was no significant difference between observed and expected species richness among wood‐inhabiting fungi. The species richness of wood‐inhabiting fungi has adjusted to the changes in forest and landscape structure more rapidly than the species richness of lichens. Differences in substrate dynamics between epiphytes on living trees and species growing on decaying logs might explain the difference between species groups. The results also indicate that population densities of red‐listed species were low, which may result in continuing extinctions of red‐listed species. The importance of WKHs might be overvalued because species may be lost if conservation efforts consider only protection and preservation of WKHs.

Evolution of the New Zealand vascular flora: Regional and provincial patterns of richness, radiation, and endemism

Analysis of species richness, radiation, and endemism in 171 list‐regions and 19 botanical provinces of the New Zealand botanical region indicates that the Late Cenozoic radiation of the New Zealand vascular flora has produced divergent phylogenetic trends in regional and provincial floras. Floristic richness at all taxonomic levels is strongly determined by land area. After accounting for area, most exceptionally species‐rich list‐regions occur immediately east of the South Island main divide, on calcareous substrates in West Nelson, or on several central North Island ranges. Depauperate floras are predominantly in the south on Auckland and Campbell Islands, and four Central Otago and two Southland ranges or basins. Family and genus richness decrease with latitude, but it appears that there has been compensatory radiation from a few herbaceous families in southern island and upland floras, so that species richness shows no latitudinal trend. We present a measure of aggregate regional endemism that is comparable between list‐regions and provinces of different floristic richness. Offshore island groups are the most insular floras, with exceptionally high endemism across different taxonomic ranks; northern island floras have high degrees of family and genus endemism and high phylogenetic diversity, while the subantarctic island floras have high species endemism and high radiation. In contrast, mainland botanical provinces all show average levels of regional endemism after correcting for species richness. With the exception of gymnosperms, the most New Zealand‐endemic plant groups have the most narrow regional distributions. We discuss latitudinal patterns of endemism among plant groups in terms of dispersal and adaptation. Land protection measures will achieve different phylogenetic outcomes in different landscapes across the New Zealand botanical region.

Contribution of alien and indigenous species to plant-community assemblages near penguin rookeries at Crozet archipelago

The influence of seabird colonies on a remote insular flora was investigated through the analysis of plant community patterns at the boundaries of three colonies of king penguins (Aptenodytes patagonicus) on the subantarctic Ile de la Possession. This study revealed that the physical and chemical impacts of these seabirds greatly influence plant assemblages (community composition, alien and native species abundance and richness). Plant richness appears to be maximum for a moderate disturbance intensity, on areas slightly influenced by penguin activities. The abundance of alien species near penguin rookeries may be due to their ability to withstand animal-induced disturbances and to efficiently colonise the stripped areas. In addition, the diversity and abundance of alien species recorded in study plots depend on the location of the colony. The closer the colony is to the permanent scientific station, the higher the number and abundance of aliens recorded.

Population genetics of threatened wild plants in Japan.

Approximately one-fourth of Japan's native plant species are threatened with extinction. To conserve these species, it is critical to evaluate genetic diversity at species-level and population-level. Some factors, including population size and geographic distribution, are known to influence the population genetic diversity of wild plant species. This article briefly reviews the population genetic studies that have been conducted on wild threatened plants in Japan. A large population size or wide geographic distribution does not always lead to large genetic diversity, suggesting that historical factors such as speciation processes and population expansion often play more important roles in determining genetic diversity than the number of remnant individuals. The mating system of a species also affects genetic diversity; predominantly selfing species tend to have smaller genetic diversity than outcrossing congeners. Another issue of concern in the conservation genetics of wild plants in Japan is the genetic diversity of insular endemics, because Japan consists of many islands, and the insular flora contains many endemic and threatened species. Previous studies on endemic plants on the Bonin and the Ryukyu Islands are reviewed. Compared to the cases of the Bonin Islands or other oceanic islands, there is much larger genetic diversity in plants endemic to the Ryukyu Islands. This difference is probably the result of the differences in the geological history of these islands.

Coevolutionary Implications of an Endemic Pleistocene Megaherbivore Fauna for Insular Floras of the California Channel Islands

Coevolutionary Implications of an Endemic Pleistocene Megaherbivore Fauna for Insular Floras of the California Channel Islands

Affinities of the marine flora of the Revillagigedo Islands, Mexico

The benthic algal flora reported for the Revillagigedo Islands comprises 205 specific infraspecific taxa: 42 Chlorophyta, 29 Phaeophyta and 134 Rhodophyta. This insular flora shares 131 taxa (54%) with other regions of the Mexican Pacific and 74 (36%) are restricted apparently to the islands. One hundred three taxa (50%) are shared with areas of the Mexican tropical Pacific, 69 (34%) with warm temperate Pacific Mexico and 66 (32%) with La Paz, the transitional zone between tropical and warm temperate Pacific Mexico. Considering more general regions, the Revillagigedo Islands flora includes apparently restricted distribution (34 spp., 16.6%), exclusively tropical (51 spp., 25%) and widely distributed eastern Pacific (33 spp., 16%) taxa. Even though we consider that the inventory of the Revillagigedo Islands and to a lesser degree the eastern tropical Pacific flora is still incomplete and in need of further taxonomic study, the floristic comparison shows a greater affinity of the Revillagigedo Islands flora with the Mexican tropical Pacific than with any other part of Mexico.

L’appauvrissement de la flore et de la végétation des îles grecques, conséquence des activités humaines

The flora and vegetation of the greek islands, especially for Crete and the Aegean Islands, are affected throughout centuries by human activities. Nevertheless the present activities are so strong that they do modify dramatically the insular flora and vegetation. The wet meadows and salt marshes of the Aegean Islands and Crete have a sensitive flora and vegetation which have suffered an important regression : some elements are now threatened with extinction because of the small area of such biotopes and the present tendency to modify and exploit these zones. The psammophilous flora and vegetation suffer also an important regression. The islands of Skiathos, Tinos and Crete are studied as examples. Other islands and islets are also threatened with human activities and offer exemplary cases. An integrated planning and a regional development aware of the balances of nature are essential for the conservation of the greek islands’ flora and vegetation.

Chromosome Numbers and their Systematic Implications in Hawaiian Lobelioideae (Campanulaceae)

Chromosome numbers are reported for 20 collections of Hawaiian Lobelioideae (Campanulaceae), representing six genera, 13 species, and two interspecific hybrids. All are n = 14. Chromosome numbers are reported for the first time for eight species of Clermontia, Cyanea, Delissea, Lobelia, and Trematolobelia; the report for Delissea is the first for that genus. Additional determinations confirmed previously reported numbers in five other species of Brighamia, Clermontia, and Cyanea. Chromosome numbers are now known for all seven genera and 20 of the 110 species. All accepted counts are n = 14. It is suggested that all Hawaiian Lobelioideae share this number and are paleotetraploid. There is no evidence that the prolific speciation evident among these plants was accompanied by euploid or aneuploid change in chromosome number. The Hawaiian Lobelioideae, particularly the monophyletic lineage of 91 baccate species, offer further support for the generalization that change in chromosome number is an uncommon mode of speciation in insular floras.

CHROMOSOME NUMBERS AND THEIR SYSTEMATIC IMPLICATIONS IN HAWAIIAN LOBELIOIDEAE (CAMPANULACEAE)

Chromosome numbers are reported for 20 collections of Hawaiian Lobelioideae (Campanulaceae), representing six genera, 13 species, and two interspecific hybrids. All are n = 14. Chromosome numbers are reported for the first time for eight species of Clermontia, Cyanea, Delissea, Lobelia, and Trematolobelia; the report for Delissea is the first for that genus. Additional determinations confirmed previously reported numbers in five other species of Brighamia, Clermontia, and Cyanea. Chromosome numbers are now known for all seven genera and 20 of the 110 species. All accepted counts are n = 14. It is suggested that all Hawaiian Lobelioideae share this number and are paleotetraploid. There is no evidence that the prolific speciation evident among these plants was accompanied by euploid or aneuploid change in chromosome number. The Hawaiian Lobelioideae, particularly the monophyletic lineage of 91 baccate species, offer further support for the generalization that change in chromosome number is an uncommon mode of speciation in insular floras.

Sir Joseph Hooker's Lecture on Insular Floras

Sir Joseph Hooker's Lecture on Insular Floras

The Meaning of z in Species/Area Regressions and the Study of Species Turnover in Island Biogeography

A simple model system involving 10 species capable of colonizing seven islands of different area was set up under various restrictions of the species' ability to persist in terms solely of island area. The slope z of the log species/log area regression is -0.25 when five of the species can persist on the smallest island, and -0.13 when seven of the species persist on the smallest island. Use of additional model data on dispersal abilities, habitat requirements and competitive interactions can also generate slopes commonly found in the island biogeographic literature. I conclude that z has no unique biological meaning and therefore adds little to our understanding of species richness of insular floras and faunas. A more fruitful approach would involve studying the biology of individual species, establishing their requirements for minimum area and habitat and determining which factors restrict their overwater dispersal. The difficulties of detecting genuine species turnover are outlined. These include bias and thoroughness of each compiler or collector, assumptions about how 'missing' species should be treated, scale (the taxon in relation to island size), the necessity for providing information on the accumulation of species per unit of collecting time, and the need to restrict attention to breeding species. Most genuine species turnover of birds and mammals seems attributable to human effects, though this is not so with plant species.

Species richness, turnover and equilibrium in insular floras near Perth, Western Australia

In 1975 lists were made of the plant species occurring on 121 limestone islands, varying from 3 m2 to 160,900 m2 in area, west of Perth. Fifty-four of the islands supported no vascular plant species. An explanation of the different number of plant species found per island (S) was sought in terms of island area (A), elevation (E), and diversity of habitat types (H). Significant linear correlations were found between S and A, S and E, and S and H. The validity of neglecting islands with zero species number in regression analyses was evaluated and found to be wanting. Small islands (area < 5000 m2) tend to have impoverished floras; a study of the exceptions shows that the impoverishment is mainly due to exposure to sea spray.Inter-island distance plays a negligible part in determining the similarities of island floras. Comparisons of the present flora lists for 20 islands with those made by G. M. Storr in 1956 or 1959 show that species turnover has occurred. Although 12 islands show an increase in plant species number (as total plants, perennials, annuals and native species), this tendency is not significant. Annual species have higher extinction rates than perennial species and alien species higher ones than native species. Alien species also have higher immigration rates than native species. Floras of islands with cormorant colonies tend to have higher extinction rates than islands without. Islands with gull rookeries have higher immigration rates of alien species than islands without. Considering all 20 islands together there are no significant differences between extinction and immigration rates. These rates are independent of island area and isolation respectively. It is suggested that seabird colonies override the importance usually ascribed to island area and isolation in influencing these rates.

The composition of the Josani Forest, Zanzibar

An analysis of the present composition of the Josani Forest, Zanzibar is discussed and the status of the forest considered. Particular interest is paid to those species used as food plants by the endemic subspecies of red colobus monkey, Colobus badius kivki Gray. The forest is shown to have Calophyllum inophyllum L. and a species of Eugenia as co-dominants. The former species is considered likely to be indigenous to Josani, not introduced as presumed by previous authors. A number of species in Josani are found widely distributed on islands in the Indian Ocean, and the relation of Josani Forest to these insular floras is discussed. It is tentatively suggested that the forest lies partially in a mature solution basin and that this has had an important influence on the present composition of the forest.

Development and Evolution of Fern Floras of Oceanic Islands

Ferns are especially useful for the study of certain biogeographic problems of migration and speciation because the species have a high and nearly equivalent capacity for spore dispersal by air transport. Dispersal can bring spores of many species to an island from a source area; the ones that become cstablished are not a random assortment of the source species. Island floras have a major element of widely distributed source area species, although these are a minor element in the source area. The endemics on islands are mostly related to narrowly distributed source species, although these are a minor element in the island flora. In an archipelago the endemics are nearly always related to source species rather than to other species of the insular flora. Establishment of a species on an island is an individual, rather than a population, phenomenon because dispersal cannot bring the variability of a source population to the island. Adaptability of the genotype-phenotype of the single spore to a new environment and sensitivity to selection are characteristics that dominate success in migration and evolutionary potential under geographic isolation. Widely and narrowly distributed source species differ in these characteristics, and these differences account for the relative proportions of the two source groups in the insular flora and their relations to insular endemics. Re-immigration can maintain gene-flow between islands and is a deterrent to the evolution of species-flocks in an archipelago. INTEREST IN ISLAND biogeography has increased with the modern orientation toward the biology, ecology, and evolution of insular biotas (Carlquist 1965, 1967; MacArthur and Wilson 1967). This Symposium is an example of the heightened interest in islands, and its main theme reflects the new perspective on island studies. The ferns are a partictularly important groutp of plants to consider in relation to insular problems because of their high dispersibility. They comprise the Class Filicopsida (Polypodiophyta, Filicineae) with 10 major farnilies, some 200 genera, and about 10,000 species. I have restricted my discussion to the smaller and more isolated islands because it is among these that migration and endemism, as they relate to dispersal, can be examined to the best advantage. Large islands such as New Guinea, Madagascar, and New Zealand present special problems because of their size, and the West Indies and smaller islands of the IndoMalayan region are so close that their fern floras do not have attribtutes of instularity. Figure 1 provides the location of the islands referred to in this paper. The degree of geographic isolation and the age of the islands have not been considered in the context of historical geology. The existence of previotus high islands, for cxample, in the Pacific (Menard and Hamilton 1963) provides an historical background for present distribtutions withotut altering their instular nature. The biota of the present Pacific islands shows evidence of its devclopment tunder strong geographic isolation. The ages of all of the islands disctussed are sufficient to allow angiosperm endemics to have differentiated (rmany of them also have fern endemics) which wotuld also be sufficient time for the operation of the processes discussed in this paper. Dispersal and migration are distinct but complcmcntary processes. Dispersal is the transport (in ferns) of spores from one place to another; migration is the successful establishment of a species in a new area after dispersal. Migration cannot take place without dispersal, btut dispersal may occur (sometimes with high frequency) without migra-

Low Altitude Mosses from Northeastern New Guinea

The mosses listed below represent collections made by Mr. Ross G. Robbins during 1958-59 in northeastern New Guinea. The 1958 collections are mostly from the Lower Rawu-Atitau area, Madang District (cited below merely, as Madang); the 1959 collections are from the Wewak-Angorum area, Sepik District (cited merely as Sepik), both from relatively low elevations. From previous experience I rather expected that these collections would be broadly representative of the Indomalayan moss flora but suprisingly enough there were many unusual records of well known species together with an astonishing number of undescribed types showing the exceptional richness of this tropical insular flora. The total of 124 species inelides 16 new records for New Guinea and 16 species described as new. Nearly three-fourths of the species are Indomalayan types, mostly of a rather broad distribution but more rarely, as shownl by Exodictyon sullivantii, Rhizogonium setosumn, Rhacopilum breviseturm and Rhizohypnella sundaensis, of a restrietedrange. Until more information from the extensive unexplored areas, especially the high peaks of the central ranges, is available, it is impossible to form any adequate idea of the extent and relationship of the New Guinea moss flora. The important contributions made by R. G. Robbins and L. J. Brass over the last two decades have provided a broad basis for future study but the full implications of the work remain to be clarified. Species preceded by an asterisk are new to New Guinea. Complete series of specimens are in the herbarium of the Commonwealth Scientific Industrial Research Organization, Canberra, Australia, and in the writer's herbarium; types of new species are in the latter collection. Collection-numbers cited in italic type are those of Mr. Robbins.

Geographical Guide to the Floras of the World

A COMPREHENSIVE world list of regional floras has long been a desideratum. It is now halfway to being realized by the publication of this volume, the first of two parts which aim at providing “an annotated summary of the available, nominally complete publications on the vascular flora and the economic botany of the world”, complete up to 1939. No list of the scope of this one has previously been published. While it enumerates more than 3,000 titles, its aim is usefulness and not bibliographical completeness. Papers dealing with only a section of the flora of any region, monographs and revisions of genera or families, or those works which are primarily ecological are excluded, as are all works of a 'popular' type intended for beginners. Geographical Guide to the Floras of the World An Annotated Selected List of Floras and Floristic Works relating to Vascular Plants, including Bibliographies and Publications dealing with Useful Plants and Vernacular Names. Part 1: Africa, Australasia, Insular Floras, North America and South America. By S. F. Blake and Alice C. Atwood. Pp. 336. (Washington: United States Dept. of Agriculture Miscellaneous Publication No. 401, 1942.) 75 cents.

GEOGRAPHICAL ISOLATION AS A FACTOR IN SPECIES FORMATION, AND ITS RELATION TO CERTAIN INSULAR FLORAS.

GEOGRAPHICAL ISOLATION AS A FACTOR IN SPECIES FORMATION, AND ITS RELATION TO CERTAIN INSULAR FLORAS Get access C. Skottsberg C. Skottsberg 1Gothenburg Search for other works by this author on: Oxford Academic Google Scholar Proceedings Linnean Society London, Volume 150, Issue 4, December 1938, Pages 286–293, https://doi.org/10.1111/j.1095-8312.1938.tb00182l.x Published: 31 May 2011

Pacific Insular Floras and Pacific Paleogeography

Pacific Insular Floras and Pacific Paleogeography