Cucumber (Cucumis sativus) and melon (C. melo) have numerous wild relatives in Asia and Australia, and the sister species of melon is from Australia MO, and approved June 16, 2010 (received for review April 19, 2010) Among the fundamental questions regarding cultivated plants is their geographic origin and region of domestication. The genus Cucumis, which includes cucumber (Cucumis sativus) and melon (Cucumis melo), has numerous wild African species, and it has therefore been assumed that melon originated in Africa. For cucumber, this seemed less likely because wild cucumbers exist in India and a closely related species lives in the Eastern Himalayas. Using DNA sequences from plastid and nuclear markers for some 100 Cucumis accessions from Africa, Australia, and Asia, we show here that melon and cucumber are of Asian origin and have numerous previously overlooked species-level relatives in Australia and around the Indian Ocean. The wild progenitor of C. melo occurs in India, and our data confirm that the Southeast Asian Cucumis hystrix is the closest relative of cucumber. Most surprisingly, the closest relative of melon is Cucumis picrocarpus from Australia. C. melo diverged from this Australian sister species approximately 3 Ma, and both diverged from the remaining Asian/Australian species approximately 10 Ma. The Asian/Australian Cucumis clade comprises at least 25 species, nine of them new to science, and diverged from its African relatives in the Miocene, approximately 12 Ma. Range reconstruction under maximum likelihood suggests Asia as the ancestral area for the most recent common ancestor of melon and cucumber, fitting with both having progenitor populations in the Himalayan region and high genetic diversity of C. melo landraces in India and China. Future investigations of wild species related to melon and cucumber should concentrate on Asia and Australia.ancestral areas | crops | economic plants | wild progenitors A mong the most fundamental and debated questions regarding the evolution of cultivated plants is their geographic origin and region of domestication (1). Recent phylogeographic and phylogenetic work on cassava, pumpkin, corn, potato, and rice (2-6) has uncovered the likely places of origin and domestication of these crops. Although many premolecular hypotheses about the domestication of particular species still require testing, it is clear that the Indo-Chinese region has produced a particularly long list of crops. These include rice (Oryza sativa), millets (Setaria spp.), beans (Vigna mungo; Vigna radiata), angled loofah (Luffa acutangula), yams (Dioscorea spp.), and taro (Colocasia esculenta) (7-9). Archaeological evidence from northern India documents these Neolithic crops from 7,000 BC onward, and by the early second millennium, there is evidence of Western crops arriving in India through trade, such as wheat, barley, lentils, grasspea, and peas (7).One of the crops domesticated in the Indo-Gangetic plain is cucumber, Cucumis sativus. Evidence for this consists in the occurrence there ...

Summary Climate change may impact most strongly on temperate lake plankton communities in spring, when light availability and water temperature change rapidly due to thermal stratification. Effects of changing light and temperature on one food‐web component transfer to other components, producing a complex interplay between physical drivers and biotic feedbacks. Understanding this interplay is important, because altered climate regimes could result in phenological mismatch between the phytoplankton spring bloom and the timing of maximum food requirements of grazers. To separate direct effects of light and temperature on spring plankton dynamics from effects mediated through micro‐ and mesograzer feedbacks, we manipulated water temperature, stratification depth and presence/absence of the mesograzer Daphnia in lake mesocosms. In early spring, stratification depth and water temperature directly influenced the light supply to phytoplankton and the growth rates of all plankton groups. Subsequently, indirect effects, including light‐dependent food supply to grazers and temperature‐dependent grazing pressure, became increasingly important. Phytoplankton and Daphnia peaked earlier in warmer treatments and reached higher peaks when stratification depth was shallower. Ciliates responded positively to increased food density and higher temperature and subsequently affected the taxonomic composition, but not the total biomass, of phytoplankton. In the absence of Daphnia, phytoplankton did not enter a distinct clear water phase. When present, Daphnia caused an extended clear water phase, maintaining phytoplankton and ciliates at low levels throughout early summer and suppressing all direct effects of physical drivers on these plankton groups. Our Daphnia treatments mimicked the high and low fish predation settings of the largely descriptive, recently revised Plankton Ecology Group (PEG) model of seasonal plankton succession and explored their responses to climate change scenarios. The results largely support the PEG model, but attribute greater importance to early season temperature effects and later season grazing effects of Daphnia. In warmer treatments, the timing of phytoplankton and zooplankton peaks tended to be more closely coupled, and temperature did not affect the height of zooplankton peaks. In line with other experiments, these results do not support the widely held concern that warming may create a trophic mismatch between phytoplankton and zooplankton and reduce spring zooplankton production.

Aim  To infer the most plausible explanations for the presence of 14 species of the Neotropical cucurbit genus Sicyos on the Hawaiian Islands, two on the Galápagos Islands, two in Australia, and one in New Zealand. Location  Neotropics, the Hawaiian and Galápagos archipelagos, Australia and New Zealand. Methods  We tested long‐problematic generic boundaries in the tribe Sicyoeae and reconstructed the history of Sicyos using plastid and nuclear DNA sequences from 87 species (many with multiple accessions) representing the group’s generic and geographic diversity. Maximum likelihood and Bayesian approaches were used to infer relationships, divergence times, biogeographic history and ancestral traits. Results  Thirteen smaller genera, including Sechium, are embedded in Sicyos, which when re‐circumscribed as a monophyletic group comprises 75 species. The 14 Hawaiian species of Sicyos descended from a single ancestor that arrived c. 3 million years ago (Ma), Galápagos was reached twice at c. 4.5 and 1 Ma, the species in Australia descended from a Neotropical ancestor (c. 2 Ma), and New Zealand was reached from Australia. Time since arrival thus does not correlate with Sicyos species numbers on the two archipelagos. Main conclusions  A plausible mechanism for the four trans‐Pacific dispersal events is adherence to birds of the tiny hard fruit with retrorsely barbed spines found in those lineages that underwent long‐distance migrations. The Hawaiian clade has lost these spines, resulting in a lower dispersal ability compared with the Galápagos and Australian lineages, and perhaps favouring allopatric speciation.

International audienceEcological consequences of global warming include shifts of species ranges toward higher altitudes and latitudes as well as temporal shifts in phenology and life-cycle events. Evidence is accumulating that increasing temperature is also linked to reduced body size of ectotherms. While temperature can act directly on body size, it may also act indirectly by affecting the timing of life-cycle events and the resulting population age and size structure, especially in seasonal environments. Population structure may, in turn, be influenced by temperature-driven changes in resource availability. In a field mesocosm experiment, we investigated how water temperature and mixed surface layer depth (a temperature-dependent determinant of light availability to phytoplankton) affected population dynamics, population age and size structure, and individual size at stage (size at first reproduction) of Daphnia hyalina during and after a phytoplankton spring bloom. Mixed layer depth was inversely related to the magnitudes of the phytoplankton spring bloom and the subsequent Daphnia peak, but had no effect on the body size of Daphnia. Conversely, temperature had no effects on abundance peaks but strongly affected the timing of these events. This resulted in at times positive, at other times negative, transient effects of temperature on mean body size, caused by asynchronous changes in population size structure in cold versus warm treatments. In contrast to mean body size, individual size at stage consistently decreased with increasing temperature. We suggest that size at stage could be used as an unbiased response parameter to temperature that is unaffected by transient, demographically driven changes in population size structure

DarwinÕs contributions to the field of biogeography, stressing the importance of his natural history specimens. Here, we illustrate how a plant collected by Darwin during his visit to Floreana and not collected since can provide insights into dispersal to oceanic islands as well as extinction of island plants, based on ancient DNA from DarwinÕs herbarium specimen.Keywords Cucurbitaceae, DarwinÕs herbarium, extinction, Galapagos, island biogeography, molecular clock, phylogenetics, plant viruses, Sicyos.During his voyage on the Beagle, Charles Darwin industriously collected natural history specimens and sent them home from various ports along the way (Briggs, 2009). On his return to Great Britain, he immediately began supervising work on the scientific results of the expedition, employing the help of specialists to record his fossils, fishes, mammals, birds and plants. Among the 209 plants that Darwin collected on the Galapagos Islands and sent to J. D. Hooker was a new species of Cucurbitaceae, Sicyos villosus J. D. Hooker (Fig. 1). Unlike his bird collections, Darwin labelled his plants by island, which is why we know that this cucurbit came from Charles Island, now Floreana. On the herbarium label, the species is described as ÔIn great beds injurious to vegetation.Õ Since then, this species has never been found again, despite intense search efforts of several botanists. Based on one fruit from a bag attached to DarwinÕs 175-year-old specimen in the Cambridge herbarium (Fig. 1, insert), one of us (H.S.) generated nuclear and chloroplast sequences to find out the affinities of this vanished mystery plant. We also tested its relationship to another endemic Galapagos cucurbit, the Santa Cruz gourd, Sicyocaulis pentagonus Wiggins, which is known from five collections on Santa Cruz and Isabela, but has not been collected in the past 35 years.Based on molecular data (Kocyan et al., 2007; Schaefer et al., 2008 Schaefer et al., , 2009, the New World Sicyoeae comprise a clade of about 150 species in 20 genera (Apatzingania, Brandegea, Cyclanthera, Echinocystis, Echinopepon, Elateriopsis, Frantzia, Hanburia, Linnaeosicyos, Marah, Microsechium, Parasicyos, Pseudocyclanthera, Rytidostylis, Sechiopsis, Sechium, Sicyocaulis, Sicyos, Sicyosperma, Vaseyanthus). Herbarium specimens of 76 Figure 1 The sole herbarium collection in existence of Sicyos villosus, collected by Darwin during his visit to Floreana in September 1835 and described as a new species by J. D. Hooker. The specimen is now in the Darwin herbarium, whose keeper, Professor J. Parker, granted permission to extract DNA from one of the seeds shown in the inset in the lower right (inset scale bar = 5 mm). Photograph by A. Tye.