Darwin’s Legacy

Why does the world exist and what or who created it? These are the questions humankind asked for thousands of years. Before Charles Darwin gave his answers, only creationism and uniformitarianism were turned to as possible reasons.

Following In Darwin’s Footsteps

Chinese paleontologists’ remarkable fossil findings buttress and expand Darwin’s theory Fossil discoveries across China are contributing, as well as offering new insights, to the ever-evolving theories presented by English naturalist Charles Darwin a century and a half ago.

Coral reef ecological pump for gathering and retaining nutrients and exporting carbon:a review and perspectives

How coral reefs with high productivity and biodiversity can flourish in oligotrophic tropical oceans has inspired substantial research on coral reef ecosystems.Increasing evidence shows that similar to water in an oasis in the desert,there are stable nutrient supplies to coral reefs in oligotrophic oceans.Here,with emphasis on the fluxes of organic matter,we summarize at the ecosystem level(1)the multiple input pathways of external nutrients,(2)the storage of nutrients in reef organisms,(3)the efficient retaining and recycling of dissolved and particulate organic matter within coral reef ecosystems,(4)the distinctly high phytoplankton productivity and biomass inside and near oceanic coral reefs,and(5)the export of reef-related organic carbon to adjacent open oceans.These properties enable coral reefs to function as ecological“pumps”for gathering nutrients across ecosystems and space,retaining and recycling nutrients within the ecosystem,supporting high phytoplankton productivity,and exporting organic carbon to adjacent open oceans.Particularly,the high phytoplankton productivity and biomass make waters around coral reefs potential hotspots of carbon export to ocean depths via the biological pump.We demonstrate that organic carbon influx is vital for coral reef ecosystems’carbon budget and carbon export.The concept of the coral reef ecological pump provides a framework to improve the understanding of the functioning of the coral reef ecosystem and its responses to disturbance.Prospects of the coral reef ecological pump in coral reef studies are discussed in changing oceans driven by human activities and global change in the Anthropocene.

Scale dependence in the phylogenetic relatedness of alien and native taxa

Aims Darwin’s naturalization hypothesis proposes that successfully established alien species are less closely related to native species due to differences in their ecological niches.Studies have provided support both for and against this hypothesis.One reason for this is the tendency for phylogenetic clustering between aliens and natives at broad spatial scales with overdispersion at fine scales.However,little is known about how the phylogenetic relatedness of alien species alters the phylogenetic structure of the communities they invade,and at which spatial scales effects may manifest.Here,we examine if invaded understorey plant communities,i.e.containing both native and alien taxa,are phylogenetically clustered or overdispersed,how relatedness changes with spatial scale and how aliens affect phylogenetic patterns in understorey communities.Methods Field surveys were conducted in dry forest understorey communities in south-east Australia at five spatial scales(1,20,500,1500 and 4500 m2).Standardized effect sizes of two metrics were used to quantify phylogenetic relatedness between communities and their alien and native subcommunities,and to examine how phylogenetic patterns change with spatial scale:(i)mean pairwise distance and(ii)mean nearest taxon distance(MNTD).Important Findings Aliens were closely related to each other,and this relatedness tended to increase with scale.Native species and the full community exhibited either no clear pattern of relatedness with increasing spatial scale or were no different from random.At intermediate spatial scales(20-500 m2),the whole community tended towards random whereas the natives were strongly overdispersed and the alien subcommunity strongly clustered.This suggests that invasion by closely related aliens shifts community phylogenetic structure from overdispersed towards random.Aliens and natives were distantly related across spatial scales,supporting Darwin’s naturalization hypothesis,but only when phylogenetic distance was quantified as MNTD.Phylogenetic dissimilarity between aliens and natives increased with spatial scale,counter to expected patterns.Our findings suggest that the strong phylogenetic clustering of aliens is driven by human-mediated introductions involving closely related taxa that can establish and spread successfully.Unexpected scale-dependent patterns of phylogenetic relatedness may result from stochastic processes such as fire and dispersal events and suggest that competition and habitat filtering do not exclusively dominate phylogenetic relationships at fine and coarse spatial scales,respectively.Distinguishing between metrics that focus on different evolutionary depths is important,as different metrics can exhibit different scale-dependent patterns.