The microevolution of the Galápagos marine iguana Amblyrhynchus cristatus assessed by nuclear and mitochondrial genetic analyses

Marine iguanas may have inhabited the Galápagos archipelago and its former, now sunken islands for more than 10 million years (Myr). It is therefore surprising that morphological and immunological data indicate little evolutionary divergence within the genus. We utilized mitochondrial DNA (mtDNA) sequence analyses and nuclear DNA fingerprinting to re-evaluate the level and pattern of genetic differentiation among 22 marine iguana populations from throughout the archipelago. Both genetic marker systems detect a low level of within-genus divergence, but they show contrasting levels of geographical subdivision among the populations. The mitochondrial gene pools of populations from different regions of the archipelago are isolated, and the mtDNA pattern appears to follow the sequence in which the islands were colonized by marine iguanas. Conversely, the nuclear DNA study indicates substantial interpopulational gene exchange, and the geographical distribution of the nuclear markers seems to be determined by isolation by distance among the populations. The natural history of marine iguanas suggests that the contrasting nuclear and mitochondrial DNA patterns result from an asymmetric migration behaviour of the two sexes, with higher (active and passive) interisland dispersal for males than females. Separate genetic analyses for the sexes appear to support this hypophesis. Based on these findings, a scenario is proposed that explains the marine iguanas' low genetic divergence, notwithstanding their long evolutionary history in the Galápagos archipelago.     

A set of highly discriminating microsatellite loci for the Galápagos marine iguana Amblyrhynchus cristatus

We describe here the cloning of 12 (7 dinucleotide, 1 trinucleotide and 4 tetranucleotide) microsatellite loci for the Galápagos marine iguana Amblyrhynchus cristatus. When tested for individuals from five different island populations on the Galápagos archipelago, high genetic diversities (9–20 alleles per locus) and heterozygosities (0.200–0.944) were observed. All loci showed no obvious deviations from Hardy–Weinberg equilibrium. The new set of microsatellite loci was able to assign individuals reliably to their island of origin, thus being able to discriminate between residents and migrants between islands.     

Human disturbance alters endocrine and immune responses in the Galapagos marine iguana (Amblyrhynchus cristatus)

Anthropogenic disturbance is a relevant and widespread facilitator of environmental change and there is clear evidence that it impacts natural populations. While population-level responses to major anthropogenic changes have been well studied, individual physiological responses to mild disturbance can be equally critical to the long-term survival of a species, yet they remain largely unexamined. The current study investigated the impact of seemingly low-level anthropogenic disturbance (ecotourism) on stress responsiveness and specific fitness-related immune measures in different breeding stages of the marine iguana (Amblyrhynchus cristatus). Specifically, we found stress-induced elevations in plasma corticosterone among tourist-exposed populations relative to undisturbed populations. We also found changes in multiple immunological responses associated with stress-related effects of human disturbance, including bacterial killing ability, cutaneous wound healing, and hemolytic complement activity, and the responses varied according to reproductive state. By identifying health-related consequences of human disturbance, this study provides critical insight into the conservation of a well-known species that has a very distinct ecology. The study also broadens the foundation of knowledge needed to understand the global significance of various levels of human disturbance.     

Ontogenetic changes in food intake and digestion rate of the herbivorous marine iguana (Amblyrhynchus cristatus,Bell)

Young reptiles have higher relative energy demands than adults, but the proposed ontogenetic changes in diet to fulfil these demands were not found in the algae-eating Galápagos marine iguanas on Santa Fé. Feeding and digestion rates were investigated to analyse how young achieve higher energy intake. Daily food intake of free ranging marine iguana hatchlings (6–11 months old) was about one third that of adults, but relative intake (g dry mass · g^–1 wet mass · day^–1) was four times higher in the hatchlings. During feeding experiments, relative daily food intake of hatchling marine iguanas was approximately three times higher than that of adults (0.042 vs 0.013 g dry mass · g^–0.8 wet mass · day^–1), and mean gut passage time was two times shorter (5 vs 10 days). The hatchlings also maintained high body temperatures (36.7° C) even under relatively cool day-time air temperatures of 32° C. Apparent digestibility of algal food measured both during feeding trials and by Mn²⁺ AAS (atomic absorption spectrometry) for free-ranging iguanas was 70%, independent of body size and temperature. The red algae prevailing in the diet were high in protein (30% dry mass) and energy (12.1 kJ/g dry mass). Diving iguanas had higher rates of energy intake than intertidal foragers, but daily intake was less. Maintenance of high body temperature enabled hatchlings to achieve high digestion rates and, combined with high relative intake, thus achieve sufficient energy intake for rapid growth despite higher mass specific metabolic rates. Estimates of biomass of marine iguanas and their algal food are given for a section of coastline on Santa Fé.     

Darwin and the Galápagos

Charles Darwin's historic visit to the Galápagos Islands in 1835 represents a landmark in the annals of science. But contrary to the legend long surrounding Darwin's famous Galápagos visit, he continued to believe that species were immutable for nearly a year and a half after leaving these islands. This delay in Darwin's evolutionary appreciation of the Galápagos evidence is largely owing to numerous misconceptions that he entertained about the islands, and their unique organic inhabitants, during the Beagle voyage. For example, Darwin mistakenly thought that the Galápagos tortoise–adult specimens of which he did not collect for scientific purposes–was not native to these islands. Hence he apparently interpreted reports of island-to-island differences among the tortoises as analogous to changes that are commonly undergone by species removed from their natural habitats. As for Darwin's finches, Darwin initially failed to recognize the closely related nature of the group, mistaking certain species for the forms that they appear, through adaptive radiation, to mimic. Moreover, what locality information he later published for his Galápagos finch specimens was derived almost entirely from the collections of three other Beagle shipmates, following his return to England. Even after he became an evolutionist, in March of 1837 (when he discussed his Galápagos birds with the eminent ornithologist John Gould), Darwin's theoretical understanding of evolution in the Galápagos continued to undergo significant developments for almost as many years as it took him to publish the Origin of Species (1859). The Darwin-Galápagos legend, with its romantic portrait of Darwin's 'eureka-like' insight into the Galápagos as a microcosmic 'laboratory of evolution', masks the complex nature of scientific discovery, and, thereby, the real nature of Darwin's genius.     

Development of primers to characterize the mitochondrial control region of Galápagos land and marine iguanas (Conolophus and Amblyrhynchus)

Primers were developed for the amplification and sequencing of the mitochondrial control region of Galápagos land (Conolophus) and marine (Amblyrhynchus) iguanas. Sequences were obtained for four land iguana samples from two islands and for 28 marine iguana samples from three islands. A series of 70–80 bp tandem repeats adjacent to the control region are described and preliminary quantification of intra‐ and interspecific sequence divergence is included.     

Recent research on the evolution of land birds on the Galápagos

A decade of research on the evolution of Galápagos land birds is reviewed, and outstanding questions to be answered are highlighted. Evolutionary studies have been restric 1 almost entirely to the four species of mockingbirds and the 13 species of Darwin's finches. Long-term field studies have been initiated on representatives of both groups. Co-operative breeding has been discovered in the mockingbirds (and hawks).
Lack's (1945, 1947) monographic treatment of Darwin's finches has been largely upheld and extended by morphological, ecological, behavioural and biochemical studies. While the phylogenetic origins of Darwin's finches still remain uncertain, the major groupings of the finches have been confirmed by the results of protein polymorphism analysis. Fossils of Darwin's finches have been discovered recently: their potential for illuminating evolutionary change has not yet been realized. Three other major developments are (1) quantitative confirmation of the role of interspecific competition in the adaptive radiation, (2) experimental confirmation of the role of morphological and song cues in species recognition, and experimental evidence of their evolution in the speciation process, and (3) direct study of natural selection on heritable quantitative traits in a population, and identification of its causes. Continuing studies of population variation are likely to reveal the contemporary importance of selection, migration and hybridization, and thereby help us to more fully understand the causes of the adaptive radiation of Darwin's finches.     

Population genetics of Galápagos land iguana (genus Conolophus) remnant populations

The Galápagos land iguanas (genus Conolophus) have faced significant anthropogenic disturbances since the 17th century, leading to severe reduction of some populations and the extinction of others. Conservation activities, including the repatriation of captive‐bred animals to depleted areas, have been ongoing since the late 1970s, but genetic information has not been extensively incorporated. Here we use nine species‐specific microsatellite loci of 703 land iguanas from the six islands where the species occur today to characterize the genetic diversity within, and the levels of genetic differentiation among, current populations as well as test previous hypotheses about accidental translocations associated with early conservation efforts. Our analyses indicate that (i) five populations of iguanas represent distinct conservation units (one of them being the recently discovered rosada form) and could warrant species status, (ii) some individuals from North Seymour previously assumed to be from the natural Baltra population appear related to both Isabela and Santa Cruz populations, and (iii) the five different management units exhibit considerably different levels of intrapopulation genetic diversity, with the Plaza Sur and Santa Fe populations particularly low. Although the initial captive breeding programmes, coupled with intensive efforts to eradicate introduced species, saved several land iguana populations from extinction, our molecular results provide objective data for improving continuing in situ species survival plans and population management for this spectacular and emblematic reptile.     

Morphological variation among populations of Lecocarpus (Asteraceae) on the Galápagos Islands

Representative samples were collected from almost all known populations of the endemic Galapagos genus Lecocarpus. Multivariate statistical methods were applied to morphological characters to investigate differentiation among species and populations. In discriminant analysis no misclassifications were made among species. Populations of L. darwinii and L. lecocarpoides were better discriminated than populations of L. pinnatifidus . Principal Component Analysis (PCA) separated species well although intermediate populations occur between L. darwinii and L. lecocarpoides . Clear patterns of within-species differentiation were seen among populations of L. darwinii and L. lecocarpoides , but not among populations of L. pinnatifidus .
Populations of L. lecocarpoides at present grow on separate islands. All populations of L. darwinii are found on San Cristóbal, but this island might have been separated into more islands in the past. Lecocarpus pinnatifidus has probably always been growing on only one island. This suggests that the sea is the major barrier to dispersal of the three species. We find it likely that the degree of reproductive isolation caused by the sea is crucial to the differentiation among populations, and that genetic drift rather than adaptation has been responsible. The analyses cast new light on the identity of classic collections made by Darwin in 1835 and Stewart in 1906. © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 154 , 523–544.     

Pollination biology of the Galápagos endemic, Tournefortia rufo-sericea (Boraginaceae)

Tournefortia rufo-sericea is an endemic member of the Galápagos angiosperm flora. Although not uncommon within the archipelago, its status is presently listed as vulnerable and, as such, a complete knowledge of its pollination biology may prove useful in preventing its decline. Pollination experiments, flower-visitor observations, nectar and fluorescence studies, as well as pollen : ovule ratio and pollen size studies were included in this investigation. The small, white flowers of this species set fruit via open pollination (81%), autonomous self-pollination (80%), diurnal pollination (80%), and nocturnal pollination (85%). Ants are the most common visitor to the flowers of this species, primarily during the day, whereas beetles and moths make visits at night. A small amount of nectar is presumably produced, as moths are often seen probing the corollas. Experiments with fluorescent dust did not support interflower pollen movement. The pollen : ovule ratio was 4972 : 1, which suggests xenogamy, and the mean pollen size was 21 µm. Despite the pollen : ovule ratio, it appears that this species exhibits a breeding strategy of facultative autogamy, in which the majority of flowers set fruit via autonomous self-pollination, but limited outcrossing may occur when pollinators are available. Conservation efforts for T. rufo-sericea should focus on the control or eradication of exotic species.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 153 , 21–31.     

Taxonomy and phytogeny of the genus Acalypha (Euphorbiaceae) in the Galápagos Archipelago

A preliminary phylogeny of the Neotropical Acalypha is proposed, and previous infrageneric classifications commented upon. New views are presented on the floral morphology; the homology of the inflorescences and of the allomorphic female flower. The Galapagos Acalypha (Euphorbiaceae, Acalyphinae) are revised; the group is established as monophyletic and its relationships are shown. The sister–group is the Neotropical A. cuspidata–complex. Four species are recognized, viz. A. baurii Robinson & Greenman, A. wiggensii Webster, A. parvula J. D. Hooker, and A. abingdonii sp. nov. A. baurii is shown to be the sister–group of A. abingdonii + A. wigginsii+A. parvula, and A. abingdonii the sister–group of A. wigginsii + A. parvula. Brief accounts are given on nomenclatural history, aspects of morphology, chromosome numbers, geographical distribution (incl. the biogeography of the Galapagos Isles), ecology, pollination biology, and population structure. Se propone una filogenia preliminar para la Acalypha neotropical y se comenta la clasificacion infragenerica anterior. Se presenta nuevos puntos de vista sobre la morfología floral, la homología de las infloresciencias y sobre las floras alomórficas femeninas. Se revisa nomenclatura y taxonomía de Acalypha de Galápagos (Euphorbiaceae, Acalyphinae); se establece el grupo como monofilético y se revelan sus relaciones: el grupo gemelo es el complejo A. cuspidata neotropical. Se reconoce cuatro especies en esta revision: A. baurii Robinson & Greenmann, A. wigginsii Webster, A. parvula J. D. Hooker, y una nueva, A. abingdonii que se describe. A. baurii parece ser gemela de A. abingdonii + A. wigginsii + A. parvula, y A. abingdonii la gemela de A. wigginsii + A. parvula. Se hace comentarios cortos sobre la historia de la nomenclatura, aspectos de morfologia, numero cromosonico, dis–tribusión geografica (incluyendo la biogeografía de las Islas Galápagos), ecologia, biología de polinizaci6n y estructura poblacional.     

Population size and trends of the Galápagos Penguin Spheniscus mendiculus

We applied a capture–mark–resight (CMR) method to estimate the population size of the Galápagos Penguin Spheniscus mendiculus . In 1999, we estimated 1198 individuals, with lower and upper 95% confidence limits of 1054 and 1403 individuals, respectively, and estimated that approximately 57% of the total population was counted in an annual census. Applying this estimate to the 2003 census, we estimated that the population size for the whole archipelago was 1351 individuals. We also applied the correction factor derived from the 1999 CMR data to other censuses carried out between 1970 and 2003 and estimated a maximum population of about 4000 individuals in 1971 when the highest numbers of Penguins were counted. Although the Penguin population size has fluctuated in the last 33 years, the overall trend shows larger populations in 1970–80 followed by relatively smaller populations and a slow recovery rate in 1983–2003. The data set also shows two major population declines (in 1983 and 1998), which are coincident with El Niño episodes.     

Scalesia gordilloi sp. nov. (Asteraceae) from the Galápagos Islands, Ecuador

Scalesia gordilloi está descrita desde la isla San Cristóbal, Islas Galápagos, Ecuador. Tiene una distribución limitada y local al lado de la costa sur en la zona vegetal árida. Está relacionada a S. divisa Anderss. y S. incisa Hook. f. Se discute la taxonomía de S. gordilloi.     

Age-related changes in hematocrit in the Galápagos sea lion (Zalophus wollebaeki) and the Weddell seal (Leptonychotes weddellii)

In mammals, hematocrit (Hct) is optimized between the divergent requirements of blood flow characteristics and oxygen transport and storage capacity. This trade‐off plays a particularly major role in marine mammals, in which oxygen demand during sustained diving requires high Hct levels. Galápagos sea lions (Zalophus wollebaeki) need a long time after birth to develop from terrestrial life to the state of an independent forager at sea. We here show that pups were born with high Hct of 45%, then reduced Hct during the first 40 d of life to 31% while they remain constantly ashore, and increased Hct again until the adult level (57%) is reached at 1 yr of age when they begin to dive for foraging at sea. A similar, but much more rapidly changing pattern is seen in Weddell seal pups, but not in northern elephant seals, where no reduction in Hct is seen after birth. These and similarly changing patterns in terrestrial mammals likely reflect species specific functional adjustments during development due to a trade‐off between the costs of circulation and the changing need to store and transport oxygen.     

A new look at evolution in the Galápagos: evidence from the late Cenozoic marine molluscan fauna

Endemism is not as common in the marine invertebrate fauna of the Galápagos Islands region as in the adjacent terrestrial biota. Marine invertebrates in the Galápagos are largely cosmopolitan species from the Panamic, Indo-Pacific, Californian, or Peruvian faunal provinces. However, an endemic component is also present in the fauna. The observed pattern among marine invertebrate organisms can be accounted for by at least two processes: (1) genetic continuity between mainland and island populations mediated through planktonic larvae; and (2) lower rates of intrinsic evolutionary change. The evolutionary scenario standardly applied to terrestrial organisms in the Galápagos, namely, adaptive radiation and speciation in reproductive isolation from mainland source populations, does not apply to all marine invertebrates. Evidence in support of the alternative scenario for marine invertebrates comes from both published records of species occurring in the islands and recent studies of fossil-bearing deposits on several islands in the archipelago. Two misconceptions–considering the islands and sedimentary deposits to be older than now thought, and equating the rate of evolution of the terrestrial biota with the marine biota–can lead to an incorrect interpretation of evolution in the Galápagos Contrasts between marine invertebrate and terrestrial organisms serve to illustrate some fundamental differences which have important evolutionary implications. Some of these are: endemism; dispersal; taxonomic relationships; island definitions; rates of evolutionary change; and age of fossils. In terms of Darwin's evolutionary scenario, terrestrial organisms represent the paradigm and marine organisms represent the paradox.     

The allopatric phase of speciation: the sharp-beaked ground finch (Geospiza difficilis) on the Galápagos islands

Using microsatellite DNA variation, morphological measurements and sonagrams made from tape-recordings in the field, we examine die allopatric differentiation of six populations of the sharp-beaked ground finch, Geospiza difficilis , in the Galapagos archipelago. We ask how and why die populations became differentiated, and consider what die differences imply about speciation. An important factor is time; G. difficilis is one of the phylogenetically oldest species. Populations became differentiated by adapting in beak morphology to different food supplies. Since beak size and shape also function in conspecific mate recognition and choice, die potential for reproductive isolation from sister and parental taxa arose as a correlated effect of natural selection on resource-exploiting traits. This conforms to a standard explanation for the origin of pre-mating isolation as a byproduct of adaptive changes in allopatry without being adaptive itself. However, diis explanation is incomplete. Vocal characteristics also differentiated, partly as a result of natural and sexual selection independent of beak size change in environments with different sound transmitting properties. An additional element of chance is indicated by a comparison of closely-related populations on two islands, Wolf and Darwin, that are geographically close, and topographically and floristically similar. The populations have markedly different vocalizations. Morphological characters, vocalizations and genetic traits do not vary concordandy among die six populations. One population (Genovesa) is genetically more similar to other congeneric species. Phenotypic similarities with G. difficilis are the result of a uniquely long retention of shared ancestral traits. Arguments under the phylogenetic species concept justify recognizing this population as a separate species, Geospiza acutirostris. Under the biological species concept it should remain as currentiy classified, G. difficilis.     

Flightlessness in the Galápagos cormorant (Compsohalieus [Nannopterum] harrisi): heterochrony, giantism and specialization

A study of flightlessness in the Galápagos cormorant (Compsohalieus [Nannopterum] harrisi) was undertaken using study skins and skeletons of C. harrisi and eight flighted confamilials; in addition, four skin specimens and disassociated skeletal elements of the extinct spectacled cormorant (C. perspicillatus) of Beringia, reputed by some to have been flightless, were studied. Anatomical specimens of C. penicillatus and C. harrisi were dissected for myological comparisons. Flightless C. harrisi is 1.6 to 2.2 times as heavy as its extant flighted congeners; males averaged 3958 g and females averaged 2715 g in total body weight. Estimates of body weight for C. perspicillatus based on femur length approximated 3900 g. Wing lengths of C. harrisi were smaller than those of any other cormorant, averaging 190 mm and 170 mm for males and females, respectively. Wing-loadings (g body mass.cm^-2 wing area) of flighted cormorants ranged from 1.0 to 1.7. Estimated wing-loadings, incorporating approximate wing areas, were 2.0 and 5.1 g.cm^-2 for C. perspicillatus and C. harrisi, respectively; the former suggests that C. perspicillatus was probably capable of laboured flight. The small wings of C. harrisi result from an c. 50% shortening of remiges, accompanied by reduced asymmetry of vane widths and increased rounding of the tips, and significant reductions in lengths of wing bones, particularly the radius and ulna. Numbers of primary and secondary remiges in C. harrisi remain unchanged. Multivariate morphometries revealed that sexual dimorphism in external and skeletal dimensions is significantly greater in C. harrisi than in flighted cormorants. Canonical analysis of six external measurements indicated that C. harrisi is distinguished primarily by its relatively short wings. Skeletal peculiarities of C. harrisi were diverse, including conformational changes in the sternum, furcula, coracoid, humerus, ulna, radius, carpometacarpus and patella. Mensural comparisons confirmed substantial reductions in elements of the pectoral girdle of C. harrisi, particularly the sternal carina, as well as the alar skeleton, especially the radius and ulna. Differential shortening of the wing elements resulted in significant differences in proportions within the wing skeleton. These unique skeletal proportions of C. harrisi, in addition to its great overall size, combine to produce an immense multivariate skeletal distance between C. harrisi and all confamilials. Sexual dimorphism in skeletal dimensions, in both total and size-corrected data, was 2–3 times greater in C. harrisi than in other phalacrocoracids sampled. Most pectoral muscles of C. harrisi were absolutely or relatively smaller than those of C. penicillatus, in spite of its larger body size. No muscles or parts thereof were lacking in the pectoral limb of C. harrisi, but a number of qualitative differences distinguished the musculature of the flightless species, including: an exceptionally tough skin involving a well-developed M. pectoralis pars abdominalis and M. latissimus dorsi interscapularis; a thin, medially obsolete and laterally extensive M. pectoralis pars thoracica; a weakly developed M. rhomboideus profundus consisting of a variably tendinous fascia invested with three fasciculi of muscle fibres; an extraordinarily thick, extensive M. obliquus externus abdominis, which, together with a unique cnemio-costal slip of smooth muscle, restricts the metapatagium through an anchoring of M. serratus superficialis metapatagialis; and the presence of a unique alular muscle named here as M. levator alulae. Fusions of the tendons of origin and insertion, respectively, of M. flexor digiti superficialis and M. flexor digiti profundus in C. harrisi, muscles derived from a common muscle primordium, and the retention of a carpometacarpal tendon of M. flexor carpi ulnaris cranialis constitute strong evidence of pectoral paedomorphosis in C. harrisi. Mensural comparisons quantified the reduction of pectoral muscles in C. harrisi and indicated that these reductions were especially pronounced in the distal musculature. Morphological characteristics of Phalacrocoracidae, together with the exploitation of localized marine food resources and weakly developed seasonal movements of Compsohalieus, may have predisposed the founding population of C. harrisi to flightlessness. Anatomical changes in C. harrisi are exceeded in degree among foot-propelled diving birds by those of only a few fossil flightless birds (e.g. Hesperomis, Chendytes). Many of the morphological peculiarities of C. harrisi are paedomorphic, although several are not attributable to developmental heterochrony. These morphological characters of flightless C. harrisi are considered with respect to locomotion, feeding ecology, reproduction and demography of the species, and are compared with those of other flightless carinates.     

The classical case of character release: Darwin's finches (Geospiza) on Isla Daphne Major, Galápagos

The history of how Darwin's medium ground finch (Geospiza fortis) on Isla Daphne Major, Galápagos became a textbook example of character release is reviewed. Four hypotheses for the evolution of the intermediate-sized Daphne fortis are examined, including genetic drift/founder effect, hybridization with the small ground finch (G'. fuliginosa) , food supply (or local adaptation hypothesis) and character release in allopatry.
Modern data suggest that genetic drift is unlikely to have been important, due to inadequate isolation and over-riding selection and introgression on Daphne. All three remaining hypotheses have probably played a role. Hybridization with G. fuliginosa occurs, although it cannot counteract the selection pressures seen during our study. Local adaptation has also occurred, with natural selection changing the relative frequencies of fortis phenotypes in response to changes in Daphne food supplies. The selection resulted from correlations between the size of seeds available, feeding behaviour and morphology. However, recent phenotypic tracking has resulted in larger, not smaller phenotypes. There is also evidence for character release in the form of diet expansion by G. fortis during periods of food shortage, and indirect evidence for interspecific competition between fortis and the cactus ground finch (G. scandens). The Daphne fortis phenotype probably represents a balance between introgression with fuliginosa, selection for larger body size in dry years and selection for smaller body size in wet years. The simple textbook account of a character shift caused by the accidental absence of competitors should be qualified to reflect the ecological complexity of the situation.     

Reproductive ecology of the endemic Lecocarpus pinnatifidus (Asteraceae) in an isolated population in the Galápagos Islands

Lecocarpus pinnatifidus is an endemic member of the Asteraceae occurring on only one island in the Galápagos archipelago. The capitula are large with female ray florets and male disc florets. They are self-compatible but this study suggests fruit set is pollen limited. Visits from Xylocopa darwini and other larger insect pollinators are rare, and small insects seem to be the main pollinators. Small insects carry few pollen grains and most likely mediate self-pollinations. Self-compatibility and seed set after selfing are the most common reproductive strategy in the Galápagos Islands and L. pinnatifidus seemingly fits well into this group.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 146 , 171–180.